¹University of Central Florida/HCA Healthcare Consortium, Tallahassee, FL, USA
²Dermatology Associates of Tallahassee, Tallahassee, FL, USA
³Florida State University College of Medicine, Tallahassee, FL, USA
^* Co-first authors

Conflict of interest: None.
Funding sources: None.
Disclaimer: This research was supported in whole or in part by HCA Healthcare and/or an HCA Healthcare affiliated entity. The views expressed in this publication represent those of the authors and do not necessarily represent the official views of HCA Healthcare or any of its affiliated entities.

Abstract:
Seborrheic dermatitis (SD) is a chronic inflammatory skin disorder most commonly affecting areas rich in sebaceous glands, such as the scalp, face, axilla, and groin. Several factors can precipitate SD development, such as colonization of Malassezia, sebocyte activity, impaired immunity, and environmental influences. Topical antifungals, corticosteroids, and calcineurin inhibitors are the current mainstay treatment of SD. Recent clinical trials have validated the efficacy of non-steroidal roflumilast 0.3% foam for the treatment of SD. In this review, we analyze the safety and efficacy profile of roflumilast 0.3% foam.

Keywords: seborrheic dermatitis, treatment, roflumilast, PDE-4 inhibitor

Introduction

Seborrheic dermatitis (SD) is a chronic inflammatory skin disorder most commonly affecting areas rich in sebaceous glands, such as the scalp, face, axilla, and groin.¹ While clinical presentations may differ, typical findings include erythematous, pruritic plaques and patches with a yellow, greasy appearance.^1,2 This condition can significantly impact quality of life due to activity limiting symptoms and emotional distress exacerbated by cosmetic ramifications.³ SD affects approximately 5% of the global population, whereas its non-inflammatory counterpart, dandruff, likely impacts closer to 50%.⁴ Despite such high prevalence, the pathogenesis and exact mechanisms via which these yeasts cause inflammation have yet to be fully elucidated.

Malassezia is a part of the human microbiome, interacting with the innate and acquired skin immune system. Innate immunity plays a critical role in initiating the initial immune response against Malassezia.⁵ Sensitization to Malassezia can cause a type I hypersensitivity reaction leading to redness, itching, and scaling.⁶ Further studies point towards Malassezia causing an irritant, non-immunogenic stimulation of the immune system, leading to complement activation and a localized increase in NK1+ and CD16+ cells.^7,8

Currently, there are many mainstay treatments for SD. Due to the underlying mechanism of Malassezia proliferation, most commonly topical antifungals are used for long-term treatment and topical corticosteroids and calcineurin inhibitors for short-term treatment (Table 1).¹ Due to the chronicity of SD, ongoing maintenance therapy is often necessary to achieve low recurrence rates of visible signs of the condition, as well as alleviate associating symptoms, such as pruritus.

Table 1

Phosphodiesterase-4 (PDE-4) inhibitors, including roflumilast, represent a significant advancement in the treatment of SD and other inflammatory conditions. These drugs work by inhibiting the PDE-4 enzyme, which plays a role in modulating inflammatory responses by breaking down cyclic adenosine monophosphate (cAMP).^9,10 Elevated levels of cAMP result in reduced inflammation, making PDE-4 inhibitors effective in managing various ongoing inflammatory disorders such as chronic obstructive pulmonary disease (COPD) and asthma.¹⁰ In dermatology, PDE-4 inhibitors have received regulatory approval in the US and Canada for plaque psoriasis, psoriatic arthritis, atopic dermatitis and, most recently, SD. They have shown promise in off-label treatment of a myriad of other inflammatory skin conditions. Apremilast is an oral PDE-4 inhibitor FDA-approved for psoriasis and psoriatic arthritis in patients ≥6 years of age. Crisaborole is a topical PDE-4 inhibitor, currently FDA-approved for atopic dermatitis in patients ≥3 months of age. Roflumilast has also demonstrated safety and efficacy in managing chronic inflammatory skin conditions, with the regulatory approval status in the US and Canada summarized in Table 2. Compared to currently available PDE-4 inhibitors, apremilast and crisaborole, used to treat skin disease, roflumilast has demonstrated greater selectivity and potency.^9,10

Table 2

Herein, the review will focus on the treatment of SD with a particular emphasis on roflumilast 0.3% foam.

Mechanism of Action

Roflumilast and its active metabolite (roflumilast N-oxide) are inhibitors of PDE-4.⁹ Inhibition of PDE-4 leads to an increase in cAMP and subsequent decrease in pro-inflammatory mediators such as interleukin (IL)-17, IL-23, tumor necrosis factor alpha, and interferon gamma.¹⁰

Clinical Trials

Phase 2¹¹

The Phase 2a study design was a parallel-group, double-blind, vehicle-controlled randomized clinical trial of once-daily roflumilast 0.3% foam. A total of 226 participants aged 18 or older were enrolled in the 8-week trial conducted at 24 sites in the US and Canada with a clinical diagnosis of SD for a 3-month long duration and affecting less than 20% body surface area, including the scalp, face, trunk, and/or intertriginous areas. Roflumilast 0.3% foam demonstrated a statistically significant increase in treatment success, with 104 participants (73.8%) achieving an Investigator Global Assessment (IGA) score of 0 or 1, compared to its vehicle. At week 8, 50 individuals (35.5%) attained an IGA score indicating clearance, while 54 patients (38.3%) achieved an IGA score signifying almost clear skin. In comparison, the vehicle group exhibited lower rates of improvement, with only 10 patients (15.2%) reaching clearance and 17 patients (25.8%) achieving almost clear status. Roflumilast patients exhibited significantly higher rates of erythema success, defined as an overall erythema score of 0 (clear) or 1 (almost clear) plus a 2-grade improvement from baseline, compared to those treated with the vehicle. At weeks 2, 4, and 8, respective absolute differences were 16.6% (95% Confidence Interval (CI): 6.4%-24.8%), 25.2% (95% CI: 13.1%-34.9%), and 23.5% (95% CI: 9.6%-35.0%). Similar results were noted for scaling success, defined as overall scaling score of 0 (clear) or 1 (almost clear) plus a 2-grade improvement from baseline. Statistically significant differences at weeks 2, 4, and 8: absolute differences were 11.8% (95% CI: -0.3% to 21.8%), 20.4% (95% CI: 6.8%-31.8%), and 28.8% (95% CI: 14.4%-41.0%), respectively. Overall, roflumilast 0.3% foam exhibited good tolerability, with a low occurrence of adverse events.

Phase 3¹²

The Phase 3 trial design was a parallel-group, double-blinded, vehicle-controlled, multicenter (50 centers) study with participants aged ≥9 years who were clinically diagnosed with SD affecting up to 20% body surface area, including the scalp, face, trunk, and/or intertriginous areas. 457 patients were randomly assigned in a 2:1 ratio to roflumilast (n = 304) or vehicle (n = 153). The primary endpoint was an IGA score of 0 (clear) or 1 (almost clear) and a ≥2-point improvement from baseline by week 8. The secondary endpoints included IGA success by weeks 2 and 4 and a ≥4-point improvement on the Worst Itch Numeric Rating Scale score (WI-NRS).

During this 8-week trial, a statistically significant amount of roflumilast treated patients (79.5%) achieved IGA success compared with vehicle (58.0%; P < 0.001). Roflumilast also demonstrated success at weeks 2 and 4, with percentages of IGA success of 43.0% versus 25.7% (P < 0.001) and 73.1% versus 47.1% (P < 0.001). At week 8, a higher percentage of patients treated with roflumilast (62.8%) achieved WI-NRS success compared to those treated with the vehicle (40.6%: P < 0.001), with improvement observed within 48 hours after the first application, respectively (Table 3).

Table 3

Safety and Tolerability

Overall, roflumilast 0.3% foam was well tolerated, and had similar rates of adverse events (AE) as the vehicle. During all phases of the study, there were no treatment emergent adverse events (TEAEs) reported as a direct result of roflumilast 0.3% foam treatment.^11,12 The most prevalent adverse reactions, observed in ≥1% of subjects across both Phase 2 and Phase 3 study groups included nasopharyngitis (1.5%), nausea (1.3%), and headache (1.1%).^11,12 Less frequent AEs included application site pruritus, application site pain, and diarrhea.^11,12 There were no significant differences between groups noted in clinical laboratory assessments. Vital signs, body weight, and body mass index indicated no clinically meaningful variations.¹² Moreover, evaluations for depression, suicidal ideation, and behavior revealed no safety concerns.¹²

Contraindications

Contraindications include individuals with a known hypersensitivity to roflumilast or any of the components in the formulation, as this can lead to severe allergic reactions. Additionally, patients with moderate to severe liver impairment (Child-Pugh B or C) should not use roflumilast, as it may exacerbate liver dysfunction.¹³ The coadministration of roflumilast with systemic CYP3A4 inhibitors or dual inhibitors that inhibit both CYP3A4 and CYP1A2 may increase roflumilast systemic exposure and result in increased adverse reactions.¹³ It should be noted that no formal drug-drug interaction studies were done with topical roflumilast and these recommendations are based on oral roflumilast, which has a much greater bioavailability.

Regulatory Approval

The roflumilast 0.3% foam formulation was approved by the US FDA in December of 2023 and Health Canada in October 2024 for the treatment of SD in individuals aged ≥9 years.¹⁴ The medication is to be applied once daily to the affected areas, with the duration determined by the healthcare provider. One pressurized can of roflumilast 0.3% foam (60 g) contains 3 mg roflumilast per 1 g.

Discussion

Current first-line therapies for SD typically include topical antifungals and topical steroids (Table 1). These treatments are often readily available and affordable, leading to their widespread use. While these are effective in many cases, some individuals require a combination of multiple topicals for control which contributes to patient non-compliance due to complex treatment regimens.⁴ Moreover, these treatments may be ineffective in some individuals and can be associated with poor tolerability due to various AEs such as local skin reactions, burning, pruritus, and blistering.⁴

Roflumilast 0.3% foam provides an additional non-steroidal anti-inflammatory treatment option in those who have failed first-line therapies or prefer a once daily treatment regimen. It marks the first regulatory approved medication for SD with a novel mechanism of action in over two decades. This foam is uniquely formulated in a water-based emollient formula without skin irritating fragrances or alcohols such as, propylene glycol, polyethylene glycol, isopropyl alcohol, or ethanol.¹⁴ It is reported to be the first-in-class drug formulated with a novel emulsifier that lacks ceramide stripping properties. The hydrating features of the vehicle itself may add to its therapeutic effect. Moreover, the non-irritating, non-steroidal formula enables use anywhere on the body, including the eyelids and genitalia. The non-greasy foam formulation lends itself to use on hairy scalps.

Roflumilast may improve adherence and tolerance due to its once daily application, potent formulation, and minimal AEs. Its greater selectivity for PDE-4 than apremilast and crisaborole, likely contributes to its low side effect profile. Few patients reported stinging, burning, application site reactions, or application site pain with roflumilast.¹² Data from key trials reported IGA success, defined as IGA of 0 (clear) or 1 (almost clear) plus ≥2-point improvement from baseline in 80% of participants, with some reaching IGA success as early as weeks 2 and 4.¹² Pruritus, measured via the WI-NRS, improved as early as 48 hours after application. These results are in-line with other first-line therapies (Table 3).

With the continual push for more effective and safer therapies, roflumilast appears to be a useful agent added to the SD armamentarium.

Conclusion

Due to its minimal AEs and favorable tolerability, the novel roflumilast 0.3% foam offers a safe treatment for the erythema, scaling, and pruritus caused by SD. Its once daily application and potent formulation provides a convenient and effective treatment for SD. This treatment highlights the importance of continued advancement in the development of innovative therapies for SD as it is essential to improve outcomes and enhance the quality of life for individuals affected by this condition.

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¹SKiN Centre for Dermatology Peterborough, ON, Canada
²Probity Medical Research, Peterborough, ON, Canada
³Queen’s University, Kingston, ON, Canada

Conflict of interest: MG has been an investigator, speaker and advisory board member for Arcutis.

Adapted from O’Toole A, Gooderham M. Topical Roflumilast for Plaque Psoriasis. Skin Therapy Lett. 2023 Sep;28(5):1-4. PMID: 37734074. Copyright 2023 by the Skincareguide.com Limited. Reprinted with permission.

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Case Presentations

Case #1

A 62-year-old female postal carrier presents with a 15-year history of plaque psoriasis which involves her elbows, dorsal hands, under the breasts and on the forehead and around the ears, total body surface area (BSA) of 3.5%. She has used numerous topical agents over the years, but most recently was prescribed hydrocortisone valerate 0.2% cream and clotrimazole for under the breasts, off-label tacrolimus 0.1% ointment for the face and ears and betamethasone valerate/calcipotriol foam for the elbows and hands. She reports using the topicals ‘when needed’ and presents with ongoing plaques in all described areas. She does admit she should probably be more consistent, but she has a busy life. Her past medical history is significant for obesity and hypertension. Her work uniform is uncomfortable and does not cover the visible areas of psoriasis making her very self-conscious. She books an appointment to discuss other options.

Case #2

A 38-year-old mechanic has a 10-year history of moderate-to-severe plaque psoriasis which requires systemic therapy. He has tried and failed methotrexate and acitretin in the past, and more recently has had success with an interleukin (IL)-23 inhibiting biologic agent started by his dermatologist. His body psoriasis cleared with the biologic, but he continues to have fissured plaques on his hands which is painful and interferes with his ability to work. He has been prescribed potent topical corticosteroid products in the past, including combination products, but he reports they are greasy, and he’s concerned about using steroids long-term. You see him in follow up, and he asks you for any other solutions.

Introduction

Plaque psoriasis is a chronic inflammatory skin condition with an estimated prevalence of 3%¹ and is characterized by scaly plaques which can be red to violaceous depending on the background skin tone. Psoriasis most commonly presents on the extensor surfaces but can involve anywhere on the body, including the scalp, face, and intertriginous areas (groin, under breasts or pannus, axillae). Most cases of plaque psoriasis are mild to moderate in severity, where half of patients have a BSA ≤3%.¹ Psoriasis significantly impacts quality of life, with the majority of patients reporting a “large impact” on their everyday life, even in those with limited BSA involvement.² Impact on quality of life is greater with special site involvement (i.e., face, groin, palms/soles) compared to no special site involvement.³ Itch is considered the most bothersome symptom in plaque psoriasis by almost half of patients.^3,4

The mainstay of treatment is topical including steroids, vitamin D analogs, retinoids, and calcineurin inhibitors (used off label), whether used as monotherapy in mild to moderate disease or as concomitant therapy with systemic agents in moderate to severe disease. Current topical therapies have limitations, however, including messy or greasy texture, complex or timeconsuming application, local side effects, or perceived inefficacy, which can all lead to lack of adherence to treatment and poor outcomes.⁵

Pathophysiology of Psoriasis and Role of Phosphodiesterase-4

Psoriasis is a chronic inflammatory disease influenced by environmental, genetic, and immunologic factors, characterized by rapid keratinocyte proliferation. The enzyme phosphodiesterase-4 (PDE4) plays a crucial role in immune cell regulation, with elevated activity in psoriatic skin promoting inflammation.⁶ PDE4 inhibitors, such as oral apremilast for moderate to severe psoriasis and crisaborole ointment for mild to moderate atopic dermatitis, are approved for use. Roflumilast, a potent PDE4 inhibitor, increases cyclic AMP, thereby reducing pro-inflammatory mediators like IL-17, IL-23, IFN-gamma, and TNF-alpha, thus normalizing immune response and keratinocyte differentiation.⁷ Roflumilast has greater affinity for PDE4 than the other currently available PDE4 inhibitors; depending on the comparator and isoform analyzed, it is approximately 25-300 times more potent than apremilast and crisaborole.^7-9

Topical Roflumilast Cream

Topical roflumilast 0.3% cream (Zoryve^TM) was approved for the treatment of plaque psoriasis including intertriginous psoriasis in adolescents (aged ≥12 years) and adults by the FDA in July 2022 and by Health Canada in April 2023; In October 2023, the FDA approved the expanded indication to include children 6-11 years of age as well. It is uniquely formulated as an emollient water-based cream designed to deliver the roflumilast molecule throughout the epidermis without disrupting the skin’s barrier function. A unique and patented emulsifier blend (Crodafos^TM CES) maintains the integrity of the lipid bilayer while facilitating delivery of roflumilast. The formulation does not contain sensitizing or irritating ingredients such as propylene glycol or fragrance, resulting in improved tolerability (compared to some other topicals currently available). Topical roflumilast 0.3% cream is also found in higher concentrations in the skin compared to that expected with oral dosing, with levels 62- to 126-fold higher in the skin compared to plasma.¹⁰ Its lipophilic and protein-affinity properties allow it to form a reservoir in the stratum corneum, enabling prolonged release. With a long half-life of 4 days, it allows for once-daily dosing, ensuring high efficacy and improved tolerability.¹⁰

Clinical Trials: Efficacy and Safety of Roflumilast

Phase 1 and 2 trials

A Phase 1/2a randomized controlled trial (NCT03392168) tested roflumilast cream 0.5%, 0.15% vs. vehicle for 28 days in patients with ≤5% BSA.¹¹ The primary endpoint was met with significant improvement in the Target Plaque Severity Score (TPSS) x target plaque area (TPA) with roflumilast 0.5% (P = .0007) and 0.15% cream (P = .0011) vs. vehicle; 66%-67% improvement from baseline to week 4 was noted with roflumilast vs. 38% for vehicle.¹¹

In a Phase 2b randomized controlled trial (NCT03638258), 331 adult patients were randomized to receive roflumilast cream 0.3%, 0.15%, or vehicle once daily for 12 weeks. The primary endpoint at 6 weeks of an Investigator Global Assessment (IGA) score of clear or almost clear (0 or 1) was reached by 28% in the roflumilast 0.3% group (P < .001), 23% in the roflumilast 0.15% group (P = .004), and 8% in the vehicle group (Figure 1A). Important secondary endpoints included an intertriginous IGA (I-IGA) response (clear or almost clear and ≥2 grade improvement from baseline) in 73% of the roflumilast 0.3% group, 44% of the roflumilast 0.15% group, and 29% of the vehicle group in the subgroup of participants with at least mild IGA intertriginous involvement (~15% of trial population).¹² Itch and itch-related sleep loss were also improved in subjects receiving roflumilast. Subjects with a baseline worst itch numeric rating scale (WI-NRS) ≥6 treated with roflumilast 0.3% cream achieved ≥4-point improvement compared with vehicle, which was significant at all time points between week 2 and week 12 (all P < .05).¹³ The least squares mean improvement in itch-related sleep loss was statistically significant for both doses of roflumilast as early as week 6 and maintained through week 12.¹³

Phase 3 trials

Two identical pivotal Phase 3 trials, DERMIS-1 (NCT04211363) and DERMIS-2 (NCT04211389), enrolled patients older than 2 years of age, with 2% to 20% BSA and an IGA of at least 2 (mild).¹⁴ A total of 439 and 442 subjects were enrolled (DERMIS-1 and DERMIS-2, respectively) and randomized to receive roflumilast cream 0.3% or vehicle. The primary endpoint was achieving IGA success (clear or almost clear [0 or 1] with ≥2 grade improvement from baseline) at 8 weeks. IGA success was achieved by participants receiving roflumilast 0.3% cream vs. vehicle by 42.4% and 6.1% (DERMIS-1) and by 37.5% and 6.9% (DERMIS-2), respectively (P < .001 for both) as shown in Figure 1B. Important secondary endpoints included I-IGA success at week 8, 75% improvement in Psoriasis Area and Severity Index (PASI75) at week 8, and itch improvement as measured by WI-NRS at weeks 2, 4, and 8. In participants with an I-IGA score of at least 2 at baseline (approximately 20% of trial population), I-IGA success at week 8 was achieved by 71.2% vs. 13.8% (DERMIS-1) and 68.1% vs. 18.5% (DERMIS-2) in roflumilast 0.3% cream vs. vehicle, respectively.¹⁴ The majority of patients achieving I-IGA success also achieved an I-IGA score of clear (0) with 63.5% vs. 10.3% (DERMIS-1) and 57.4% vs. 7.4% (DERMIS-2) (P < .001) clearing intertriginous areas with roflumilast 0.3% vs. vehicle, respectively. PASI75 was reached with roflumilast 0.3% vs. vehicle in 41.6% vs. 7.6% (P <.001) and 39% vs. 5.3% (P < .001) in DERMIS-1 and DERMIS-2, respectively. Itch, the most bothersome symptom of psoriasis, also improved in patients with a baseline WI-NRS score of ≥4 at baseline. WI-NRS reduction of at least 4 points from baseline was achieved as early as week 2 in 34.9% vs. 22% (DERMIS-1, P = .12) and 41.9% vs. 21.1% (DERMIS-2, P = .003) and at week 8 in 67.5% vs. 26.8% (DERMIS-1, P < .001) and 69.4% vs. 35.6% (DERMIS-2, P < .001).¹⁴

Topical roflumilast was well tolerated with rates of treatment emergent adverse effects (TEAEs) similar in both groups: DERMIS-1 (roflumilast: 25.2% and vehicle: 23.5%) and DERMIS-2 (roflumilast: 25.9% and vehicle: 18.9%).¹⁴ Less than 1% of patients in any group experienced a serious adverse event. Rates of discontinuation due to TEAEs were low and similar between groups. The most commonly reported TEAEs were headache and diarrhea consistent with the effects of oral PDE4 inhibition, but present at much lower rates than seen with oral agents. Diarrhea was mild to moderate and reported in 3.5% and 2.8% of participants receiving roflumilast in DERMIS-1 and DERMIS-2, respectively, compared to none in the vehicle group. No patients interrupted therapy or discontinued due to diarrhea.¹⁴ Headache was reported in 1% and 3.8% in the roflumilast groups and 1.3% and 0.7% in the vehicle groups. The cream was well tolerated with low rates of application site pain: DERMIS-1 (roflumilast: 0.7% and vehicle: 0.7%) and DERMIS-2 (roflumilast: 1.4% and vehicle: 0%). Investigator-rated tolerability was consistent with patient-rated tolerability, with 98- 99% of roflumilast patients and 98% of vehicle patients showing no signs of irritation and 99% of patients reporting ‘no or mild’ sensation with application when assessed at both weeks 4 and 8.¹⁴

Long-term Use of Topical Roflumilast

Long-term use of roflumilast was investigated in a 52-week open-label extension (OLE) of the Phase 2b study.¹⁵ There were two cohorts in the OLE: cohort 1 (n=230) was comprised of patients who completed the initial 12-week phase of the Phase 2b study (for a total of 64 weeks of therapy), and cohort 2 (n=102) had naïve patients with a diagnosis of at least mild psoriasis for a minimum of 6 months. The completion rate after 52 weeks was 73.5%, with low rates of discontinuation due to TEAEs or inefficacy, and the majority of discontinuations were due to withdrawal or loss of follow-up considering these trials were conducted during the COVID pandemic. The proportion of patients achieving IGA success was consistent over time, with 34.8% of cohort 1 patients and 39.5% of cohort 2 patients achieving IGA success with 64 weeks and 52 weeks of as-needed therapy, respectively. I-IGA success was achieved by 60% at week 12 and maintained by 66.7% of cohort 2 patients by week 52 but was not recorded in cohort 1 patients. Of the patients who achieved clear or almost clear skin during the open label portion, the mean durability of maintaining their response was 10 months.¹⁶ Topical roflumilast was well tolerated in the OLE, with the majority of TEAEs rated mild or moderate, 97% considered unrelated to treatment, and ≥97% showed no signs of irritation on physician assessment.¹⁵

Discussion

PDE4 inhibition with topical roflumilast is a promising nonsteroidal option for patients with plaque psoriasis of varying severities. Key data from the pivotal trials, DERMIS-1 and DERMIS-2, report IGA success in approximately 40% of study participants with psoriasis ranging from mild to severe. Results are supported by earlier phase studies measured at earlier time points. IGA success was noted as early as week 4, and responses were maintained to week 64 with as-needed use, suggesting that once a response is obtained, it can likely be sustained over time. Itch, the most bothersome symptom of plaque psoriasis, improved by 2 weeks (the first assessed time point) in all studies and itch improvement maintained over time. Itch-related sleep loss also improved compared to vehicle. Early responses such as itch and sleep improvement can encourage adherence to therapy and improve outcomes.

Given the spectrum of obstacles in the treatment of plaque psoriasis, including patient adherence and tolerance with topical therapies, as well as the management of itch and special sites (e.g., face and intertriginous areas), topical roflumilast appears to address these challenges. Individuals with psoriasis are often prescribed multiple topical medications to treat different skin areas, which contributes to a complicated treatment regimen and patient non-adherence. Topical roflumilast addresses this significant unmet need with its once-daily, non-steroidal and carefully designed vehicle that is appropriate for use on most body areas, avoiding the need for multiple prescriptions and simplifying the treatment regimen. A foam formulation is also being developed for use on the body and scalp.

The PASI75 responses noted with topical roflumilast were also comparable with a recent trial of oral apremilast for patients with mild to moderate psoriasis (ADVANCE trial, NCT03721172).¹⁷ With similar baseline characteristics (PASI 6-7, BSA 6-7% and the majority of patients with IGA 3 or moderate severity) in DERMIS-1/ DERMIS-2 and the ADVANCE trial, the proportion of patients achieving PASI75 were similar or better with roflumilast compared to oral apremilast. The comparability of a topical therapy demonstrating efficacy that is similar to or better than an oral PDE4 agent such as apremilast, can be explained by the properties of topical roflumilast, which include the lipophilicity and reservoir in the stratum corneum combined with the higher affinity of roflumilast for PDE4. In patients with mild to moderate psoriasis, topical roflumilast may potentially delay or even avoid the need for oral therapy by providing similar efficacy. The limitation will be patients with higher BSA where the risk of TEAEs, such as diarrhea, may be higher or those with psoriatic arthritis where a systemic therapy may be preferred.

Case Follow Up

Case #1 continued

After further discussion of options, this 62-year-old woman does not wish to start a systemic medication and would like to continue with topical therapy. For more effective control, she requires a more simplified treatment regimen and more education on how to use topical therapies effectively. Reducing the number of prescriptions and applications per day can simplify her busy life, so topical roflumilast 0.3% cream is one product that she can use on all areas of psoriasis once a day, making this convenient and easy for her. Alternatively, she could reduce her current regimen and use off-label tacrolimus 0.1% ointment twice daily on the face, ears, and body folds and the betamethasone dipropionate/calcipotriol foam once daily on the hands and elbows. Education on optimal use of these products is required to inform that they need to be continued until the skin is clear and then used as needed.

Case #2 continued

The 38-year-old male is looking for optimization of his current biologic therapy to improve the residual psoriasis on his hands and his preference is to not use steroids. Current options include: adding a non-steroidal, non-greasy, once-daily topical, such as roflumilast 0.3% cream; adding back an oral systemic medication such as acitretin in addition to his biologic; or increasing the frequency of his biologic injection. His preference is to try a new topical agent to avoid taking more systemic medication. After 4 months of follow up of using roflumilast 0.3% cream, his fissures have healed and his hands are almost clear. Not only does he feel better at work, but he has been able to re-join his softball league this year.

Conclusion

Targeting PDE4 with a highly selective inhibitor such as roflumilast is a proven effective strategy for the treatment of plaque psoriasis. Topical roflumilast cream 0.3%, already approved by Health Canada and the FDA for use in adolescents and adults, has demonstrated efficacy and tolerability. It is nonsteroidal, administered once daily, and highly potent, yet delivered in a cosmetically elegant formulation that is well tolerated by patients. It can be used on most body areas, including the sensitive intertriginous regions and face, making one product suitable for treating all areas of involvement. Topical roflumilast will offer patients and their health care providers a simple, convenient, safe, effective, and durable therapeutic option for the management of psoriasis.

¹SKiN Centre for Dermatology, Peterborough, ON, Canada
²Probity Medical Research, Waterloo, ON, Canada
³Queen’s University, Kingston, ON, Canada

Conflict of interest: A. O’Toole has been an investigator, speaker, or advisory board member for, or received a grant, or an honorarium from AbbVie, Amgen, Arcutis Biotherapeutics, ASLAN Pharmaceuticals, Bausch Health, Boehringer Ingelheim, Bristol-Myers Squibb, Celgene, Dermira, Dermavant, Eli Lilly, Galderma, GSK, Incyte, Janssen, LEO Pharma, Moonlake, Nimbus, Novartis, Pfizer, Regeneron, Sanofi-Aventis/Genzyme, Sun Pharma, UCB and Ventyx. M. Gooderham has been an investigator, speaker, or advisory board member for, or received a grant, or an honorarium from AbbVie, Akros Pharma, Amgen, AnaptysBio, Arcutis Biotherapeutics, Aristea, ASLAN Pharmaceuticals, Bausch Health, Boehringer Ingelheim, Bristol-Myers Squibb, Celgene, Coherus, Dermira, Dermavant, Eli Lilly, Galderma, GSK, Incyte, Janssen, Kyowa Kirin, LEO Pharma, MedImmune, Moonlake, Nimbus, Novartis, Pfizer, Regeneron, Reistone, Roche, Sanofi-Aventis/Genzyme, Sun Pharma, UCB and Ventyx.
Funding: None.

Abstract:
Roflumilast is a highly selective phosphodiesterase-4 inhibitor for the treatment of plaque psoriasis. Topical roflumilast 0.3% cream, approved by the US FDA and Health Canada for use in adolescents and adults, has proven efficacy and tolerability. It is non-steroidal, administered once-daily, and highly potent, with a unique delivery formulation. It can be used on most body areas, including the sensitive intertriginous regions and face. Herein, we review the safety and efficacy of roflumilast 0.3% cream, as demonstrated in clinical trials.

Keywords: roflumilast, PDE4 inhibitor, topical therapy, plaque psoriasis, intertriginous psoriasis, inverse psoriasis

Introduction

Plaque psoriasis is a chronic inflammatory skin condition with an estimated prevalence of 3%¹ and is characterized by scaly plaques which can be red to violaceous depending on the background color of skin. Psoriasis most commonly presents on the extensor surfaces but can involve anywhere on the body, including the scalp, face, and intertriginous areas. Most cases of plaque psoriasis are mild to moderate in severity, where half of patients have a body surface area (BSA) ≤3% and three-quarters have a BSA ≤10%.¹ Psoriasis significantly impacts quality of life, with the majority of patients reporting a “large impact” on their everyday life, even in those with limited BSA involvement.² Impact on quality of life is greater with special site involvement (i.e., face, groin, palms/soles) compared to no special site involvement.³ Itch is considered the most bothersome symptom in plaque psoriasis by almost half of patients.^3,4

The mainstay of treatment is topical including steroids, vitamin D analogs, retinoids, and calcineurin inhibitors (used off label), whether used as monotherapy in mild to moderate disease or as concomitant therapy with systemic agents in moderate to severe disease. Current topical therapies have limitations, however, including messy or greasy texture, complex or time-consuming application, local side effects, or perceived inefficacy, which can all lead to lack of adherence to treatment and poor outcomes.⁵ Indeed, almost 80% of patients with a BSA of ≤10% were very dissatisfied with their treatment in one US survey.²

Pathophysiology of Psoriasis and Role of Phosphodiesterase-4

Environmental, genetic, and immunologic factors play a role in this complex, chronic, multifactorial inflammatory disease that involves hyperproliferation of the keratinocytes with an increase in epidermal cell turnover rate. Phosphodiesterase-4 (PDE4) is a key enzyme involved in immune cell homeostasis. Elevated PDE4 activity in psoriatic skin leads to an increase in pro-inflammatory pathogenic mediators underlying plaque psoriasis,⁶ making PDE4 a suitable target in disease management. PDE4 inhibitors have been approved for use in dermatology, including oral apremilast for moderate to severe plaque psoriasis (and psoriatic arthritis) and crisaborole ointment for mild to moderate atopic dermatitis. Roflumilast is a selective and highly potent inhibitor of PDE4,⁷ resulting in an increase in cyclic 3′,5′-adenosine monophosphate (cAMP) activity and subsequent decrease in the expression levels of key pro-inflammatory mediators of psoriasis including interleukin (IL)-17, IL-23, interferon‐gamma and tumor necrosis factor-alpha.⁶ Reducing pro-inflammatory mediators helps balance the immune response and normalizes keratinocyte differentiation.⁶ Roflumilast has greater affinity for PDE4 than the other currently available PDE4 inhibitors used to treat skin disease; depending on the comparator and isoform analyzed, it is approximately 25-300 times more potent than apremilast and crisaborole.^7-9

Topical Roflumilast

Topical roflumilast 0.3% cream (Zoryve^TM) was approved by the US FDA for the treatment of plaque psoriasis including intertriginous psoriasis in adolescents (aged ≥12 years) and adults in July 2022, with Health Canada approval gained in April 2023. It is uniquely formulated as an emollient water-based cream designed to deliver the roflumilast molecule throughout the epidermis without disrupting the skin’s barrier function or extracting lipids from the epidermis. A unique and patented emulsifier blend (Crodafos^TM CES) maintains the integrity of the lipid bilayer while facilitating delivery of roflumilast. The composition of Crodafos^TM CES includes cetearyl alcohol, dicetyl phosphate, and ceteth-10 phosphate which allows roflumilast to diffuse through the epidermis by saturating the stratum corneum and subsequently entering the dermis via the intracellular space. The formulation does not contain ingredients such as propylene glycol or fragrance, resulting in improved tolerability (compared to some other topicals currently available). Topical roflumilast 0.3% cream is also found in higher concentrations in the skin compared to that expected with oral dosing, with levels 61.8- to 126-fold higher in the skin compared to plasma.¹⁰ The lipophilic, protein-affinity and water-insoluble properties of topical roflumilast leads to reservoir formation in the stratum corneum and prolonged release into the skin and systemic circulation. In fact, topical roflumilast has a long half-life of 4 days,¹⁰ affording the ability for once-daily dosing, high efficacy and improved tolerability. The tolerability and low rate of adverse effects are attributable to reduced bioavailability in the topical form compared to the oral form of roflumilast.¹⁰

Clinical Trials: Efficacy and Safety of Roflumilast

Topical roflumilast has proven efficacy and safety in multiple clinical trials. A Phase 1/2a randomized controlled trial (NCT03392168) tested roflumilast cream 0.5%, 0.15% vs. vehicle for 28 days in patients with ≤5% BSA.¹¹ The primary endpoint was met with significant improvement in the Target Plaque Severity Score (TPSS) x target plaque area (TPA) with roflumilast 0.5% (P = .0007) and 0.15% cream (P = .0011) vs. vehicle; 66%-67% improvement from baseline to week 4 was noted with roflumilast vs. 38% for vehicle.¹¹

In a Phase 2b randomized double-blinded controlled trial (NCT03638258), 331 adult patients were randomized 1:1:1 to receive roflumilast cream 0.3%, 0.15%, or vehicle once daily for 12 weeks. The primary endpoint at 6 weeks of an Investigator Global Assessment (IGA) score of clear or almost clear (0 or 1) was reached by 28% in the roflumilast 0.3% group (P < .001), 23% in the roflumilast 0.15% group (P = .004), and 8% in the vehicle group (Figure 1A). The mean change in Psoriasis Area and Severity Index (PASI) from baseline at week 6 was -50.0%, -49.0%, and -17.8%, in roflumilast 0.3%, roflumilast 0.15%, and vehicle, respectively. Important secondary endpoints included an intertriginous IGA (I-IGA) response (clear or almost clear and ≥2 grade improvement from baseline) in 73% of the roflumilast 0.3% group, 44% of the roflumilast 0.15% group, and 29% of the vehicle group in the subgroup of participants with at least mild IGA intertriginous involvement (~15% of trial population).¹² Itch and itch-related sleep loss were also improved in subjects receiving roflumilast. Subjects with a baseline worst itch numeric rating scale (WI-NRS) ≥6 treated with roflumilast 0.3% cream achieved ≥4-point improvement compared with vehicle, which was significant at all time points between week 2 and week 12 (all P < .05).¹³ The least squares mean improvement in itch-related sleep loss was statistically significant for both doses of roflumilast as early as week 6 and maintained through week 12.¹³

Two identical pivotal Phase 3 trials, DERMIS-1 (NCT04211363) and DERMIS-2 (NCT04211389), enrolled patients older than 2 years of age, with 2% to 20% BSA and an IGA of at least 2 (mild).¹⁴ A total of 439 and 442 subjects were enrolled (DERMIS-1 and DERMIS-2, respectively) and randomized 2:1 to receive roflumilast cream 0.3% or vehicle. The primary endpoint was achieving IGA success (clear or almost clear [0 or 1] with ≥2 grade improvement from baseline) at 8 weeks. IGA success was achieved by participants receiving roflumilast 0.3% cream vs. vehicle by 42.4% and 6.1% (DERMIS-1) and by 37.5% and 6.9% (DERMIS-2), respectively (P < .001 for both) as shown in Figure 1B. Important secondary endpoints included I-IGA success at week 8, 75% improvement in PASI (PASI75) at week 8, and itch improvement as measured by WI-NRS at weeks 2, 4, and 8. In participants with an I-IGA score of at least 2 at baseline (approximately 20% of trial population), I-IGA success at week 8 was achieved by 71.2% vs. 13.8% (DERMIS-1) and 68.1% vs. 18.5% (DERMIS-2) in roflumilast 0.3% cream vs. vehicle, respectively.¹⁴ The majority of patients achieving I-IGA success also achieved an I-IGA score of clear (0) with 63.5% vs. 10.3% (DERMIS-1) and 57.4% vs. 7.4% (DERMIS-2) (P < .001) clearing intertriginous areas with roflumilast 0.3% vs. vehicle, respectively. PASI75 was reached with roflumilast 0.3% vs. vehicle in 41.6% vs. 7.6% (P < .001) and 39% vs. 5.3% (P < .001) in DERMIS-1 and DERMIS-2, respectively. Itch, the most bothersome symptom of psoriasis, also improved in patients with a baseline WI-NRS score of ≥4 at baseline. WI-NRS reduction of at least 4 points from baseline was achieved as early as week 2 in 34.9% vs. 22% (DERMIS-1, P = .12) and 41.9% vs. 21.1% (DERMIS-2, P = .003) and at week 8 in 67.5% vs. 26.8% (DERMIS-1, P < .001) and 69.4% vs. 35.6% (DERMIS-2, P < .001).¹⁴

Topical roflumilast was well tolerated with rates of treatment emergent adverse effects (TEAEs) similar in both groups: DERMIS-1 (roflumilast: 25.2% and vehicle: 23.5%) and DERMIS-2 (roflumilast: 25.9% and vehicle: 18.9%).¹⁴ Less than 1% of patients in any group experienced a serious adverse event. Rates of discontinuation due to TEAEs were low and similar between groups. The most commonly reported TEAEs were headache and diarrhea consistent with the effects of oral PDE4 inhibition, but present at much lower rates than seen with oral agents. Diarrhea was mild to moderate and reported in 3.5% and 2.8% of participants receiving roflumilast in DERMIS-1 and DERMIS-2, respectively, compared to none in the vehicle group. No patients interrupted therapy or discontinued due to diarrhea.¹⁴ Headache was reported in 1% and 3.8% in the roflumilast group and 1.3% and 0.7% in the vehicle group. The cream was well tolerated with low rates of application site pain: DERMIS-1 (roflumilast: 0.7% and vehicle: 0.7%) and DERMIS-2 (roflumilast: 1.4% and vehicle: 0%). Investigator-rated tolerability was consistent with patient-rated tolerability, with 98- 99% of roflumilast patients and 98% of vehicle patients showing no signs of irritation and 99% of patients reporting ‘no or mild’ sensation with application when assessed at both weeks 4 and 8.¹⁴

Long-term Use of Topical Roflumilast

Long-term use of roflumilast was investigated in a 52-week openlabel extension (OLE) of the Phase 2b study.¹⁵ There were two cohorts in the OLE: cohort 1 (n=230) was comprised of patients who completed the initial 12-week phase of the Phase 2b study (for a total of 64 weeks of therapy), and cohort 2 (n=102) had naïve patients with a diagnosis of at least mild psoriasis for a minimum of 6 months. The completion rate after 52 weeks was 73.5%, with low rates of discontinuation due to TEAEs or inefficacy, and the majority of discontinuations were due to withdrawal or loss of follow-up. The proportion of patients achieving IGA success was consistent over time, with 34.8% of cohort 1 patients and 39.5% of cohort 2 patients achieving IGA success with 64 weeks and 52 weeks of as-needed therapy, respectively. I-IGA success was achieved by 60% at week 12 and maintained by 66.7% of cohort 2 patients by week 52 but was not recorded in cohort 1 patients. Of the patients who achieved clear or almost clear skin during the open label portion, the mean durability of maintaining their response was 10 months.¹⁶ Topical roflumilast was well tolerated in the OLE, with the majority of TEAEs rated mild or moderate, 97% considered unrelated to treatment, and ≥97% showed no signs of irritation on physician assessment.¹⁵

Discussion

PDE4 inhibition with topical roflumilast is a promising non-steroidal option for patients with plaque psoriasis of varying severities. Key data from the pivotal trials, DERMIS-1 and DERMIS-2, report IGA success in approximately 40% of study participants with psoriasis ranging from mild to severe. Results are supported by earlier phase studies measured at earlier time points. IGA success was noted as early as week 4, and responses were maintained to week 64 with as-needed use, suggesting that once a response is obtained, it can likely be sustained over time. Itch, the most bothersome symptom of plaque psoriasis, improved by 2 weeks (the first assessed time point) in all studies and itch improvement maintained over time. Itch-related sleep loss also improved compared to vehicle. Early responses such as itch and sleep improvement can encourage adherence to therapy and improve outcomes.

Given the spectrum of obstacles in the treatment of plaque psoriasis, including patient adherence and tolerance with topical therapies, as well as the management of itch and special sites (e.g., scalp and intertriginous areas), topical roflumilast appears to address these challenges. Individuals with psoriasis are often prescribed multiple topical medications to treat different skin areas, which contributes to a complicated treatment regimen and patient non-adherence. Topical roflumilast addresses this significant unmet need with its once-daily, non-steroidal and carefully designed vehicle that is appropriate for use on most body areas, avoiding the need for multiple prescriptions and simplifying the treatment regimen. A foam formulation is also being developed for use on the body and scalp.

The PASI75 responses noted with topical roflumilast were also comparable with a recent trial of oral apremilast for patients with mild to moderate psoriasis (ADVANCE trial, NCT03721172).17 With similar baseline characteristics (PASI 6-7, BSA 6-7% and the majority of patients with IGA 3 or moderate severity) in DERMIS-1/ DERMIS-2 and the ADVANCE trial, the proportion of patients achieving PASI75 were similar or better with roflumilast compared to oral apremilast. In ADVANCE, 21.6% of those receiving oral apremilast 30 mg twice daily achieved PASI75 compared to 4.1% receiving placebo at 16 weeks. In DERMIS-1 and DERMIS-2, after 8 weeks of therapy, 41.6% and 39% of roflumilast patients achieved PASI75 compared to 7.6% and 5.3% of vehicle patients, respectively. The comparability of a topical therapy demonstrating efficacy that is similar to or better than an oral PDE4 agent such as apremilast, can be explained by the properties of topical roflumilast, which include the lipophilicity and reservoir in the stratum corneum combined with the higher affinity of roflumilast for PDE4. In patients with mild to moderate psoriasis, topical roflumilast may potentially delay or even avoid the need for oral therapy by providing similar efficacy. The limitation will be patients with higher BSA where the risk of TEAEs, such as diarrhea, may be higher or those with psoriatic arthritis where a systemic therapy may be preferred.

Conclusion

Targeting PDE4 with a highly selective inhibitor such as roflumilast is a proven effective strategy for the treatment of plaque psoriasis. Topical roflumilast cream 0.3%, already approved by Health Canada and the FDA for use in adolescents and adults, has demonstrated efficacy and tolerability. It is non-steroidal, administered oncedaily, and highly potent, yet delivered in a cosmetically elegant formulation that is well tolerated by patients. It can be used on most body areas, including the sensitive intertriginous regions and face, making one product suitable for treating all areas of involvement. Topical roflumilast will offer patients and their health care providers a simple, convenient, safe, effective, and durable therapeutic option for the management of psoriasis.

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Abstract

Psoriasis vulgaris is a chronic, immune-mediated inflammatory skin disease affecting 2-4% of the Canadian population. Lifelong management is required. While most psoriasis vulgaris cases are mild-to-moderate (>80%) and do not require systemic treatment, these cases can still be particularly challenging to treat as topical therapies present limitations, including efficacy and administration, leading to poor long-term treatment compliance and unsatisfactory treatment responses. The intent of this paper is to provide physicians with a clinically relevant review of the currently available and newly developed topical therapies for psoriasis, the practice guidelines for topical management of mild-to-moderate psoriasis, and the common pitfalls and mitigation strategies to encourage long-term treatment compliance.

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Introduction

Psoriasis is a common immune-mediated skin disease affecting ~2-4% of the population in North America.¹ In nearly one-third of cases, disease begins during the first 2 decades of life and follows a chronic and persistent course, resulting in high cumulative lifetime disability.² Psoriasis is divided into 4 major clinical forms, including plaque psoriasis, guttate psoriasis, erythrodermic psoriasis and pustular psoriasis.³ Plaque psoriasis represents >90% of cases and will be the focus of this review. Classically, plaque psoriasis affects the trunk as well as the extensor surfaces of the elbows and knees; it can also affect other body sites, giving rise to regional variants such as scalp, face, intertriginous, palmoplantar, genital and nail psoriasis.³

Because psoriasis is often localized to visible and/or special body sites (knees, elbows, trunk and scalp) and is commonly associated with pain and itch, it often causes significant physical and psychological burdens.⁴ Stigmatization is common and contributes to poor health-related quality of life (HRQoL), elevated risk of multiple health comorbidities, and increased barrier to treatment.⁵ Indeed, a recent Global Burden of Disease (GBD) study ranked psoriasis as the second contributor to all skin-related Disability Adjusted Life Years (DALYs).⁶ The GBD study highlighted an increase in prevalence and morbidity of psoriasis globally, with North America and Europe being particularly affected, emphasizing the significant burden that psoriasis imposes on both individuals and society as a whole.⁶

Mild, moderate, and severe psoriasis are defined as plaques affecting <3%, between 3-10%, and >10% of body surface area (BSA), respectively.¹ Much progress has been realized in regards to managing severe disease with the approval of numerous advanced systemic therapies, including biologics and small molecules.⁷ Unfortunately, in contrast to severe disease, there has been very limited advancement in the management of mild-to-moderate disease, which affects >80% of the psoriatic patient population.^8,9 Mild psoriasis is typically managed with lifelong skin-directed topical therapies.¹⁰ Topical therapies are also often used to treat severe psoriasis vulgaris, either as monotherapy or as an adjunct to phototherapy and/or systemic therapy.¹⁰

The most commonly used topical therapies in psoriasis include corticosteroids, vitamin D3 analogues, retinoids, calcineurin inhibitors, keratolytics and tar. Multiple fixed-ingredient combination products have become commercially available in the last 20 years with the aim to overcome challenges related to lack of efficacy, compliance and adverse events.¹¹

Our objective is to review: 1) the currently available and newly developed topical therapies, both single and fixed-dose combination products; 2) clinical practice guidelines specific to the topical treatment of psoriasis; and 3) common pitfalls and mitigation strategies when managing psoriasis with topical therapies. While we recognize the importance of behavioural modification and skin care in the management of psoriasis vulgaris of all severities, we refer the reader to the review article by Ko et al. on the topic.¹²

Literature Search

This narrative literature review included studies that examined currently available therapies for psoriasis from 2010 to present. The review was conducted using the PubMed and Embase databases with the following search terms: (psoriasis) AND [(corticosteroids) OR (topical corticosteroids) OR (topical corticosteroids AND salicylic acid) OR (topical corticosteroids AND coal tar) OR (calcipotriol) OR (calcitriol) OR (tacalcitol) OR (pimecrolimus) OR (tacrolimus) OR (tazarotene) OR (retinoids) OR (corticosteroid* AND calcipotriol) OR (corticosteroid* AND calcitriol) OR (corticosteroids AND tazarotene) OR (roflumilast) OR (tapiranof) OR (topical treatment)] as either keywords or MeSH terms. Clinicaltrials.gov website was also searched for ongoing Phase II and III clinical trials. References of identified manuscripts were manually extracted to identify additional articles. Only articles published in English were considered. Articles were included if they reported on treatment of psoriasis in humans, regardless of study type. All publications were independently assessed by SG and EN first by screening titles, then abstract, followed by full-length manuscripts. Any discrepancies were discussed and resolved.

Topical Therapies for Psoriasis – Our Current Toolbox

Psoriasis is a chronic disease that requires a life-long treatment. Most patients are managed with topical treatments, therefore, it is important to recognize all presently available therapeutic options, taking into account their respective efficacy, safety profile, and usage considerations. Currently, available treatments that will be discussed include topical corticosteroids (TCS), vitamin D3 analogues, calcineurin inhibitors (TCI), tar-based preparations, retinoids, and combination therapies.¹³ These therapies can be used to induce skin clearance and to maintain disease control.¹⁴ Monotherapies with dithranol and salicylic acid will not be discussed, as their clinical use is limited. A clinical timeline of topical therapies for psoriasis is provided in Figure 1. This section will first discuss efficacy and safety considerations of monotherapies followed by combination treatments. Novel therapies, established or previously published guidelines for topical medications use and general recommendations to improve compliance are discussed in following sections.

Monotherapies

Topical Corticosteroids (TCS)

TCS have been used to treat psoriasis for over 60 years.¹⁵ TCS exert broad anti-inflammatory, immunosuppressive, and antimitotic effects.¹⁶ The most recent systematic review that we have identified focusing on TCS efficacy and safety in psoriasis dates back to 2012.¹⁵ It included 50 randomized controlled trials (RCTs), of which only 11 were placebo controlled. Potent and ultra-potent TCS were used in different formulations to induce and/or maintain disease control. Only 5 studies used the Psoriasis Area and Severity Index (PASI) assessment tool to measure efficacy outcomes. The mean percentage change in the PASI from baseline to 4-8 weeks ranged from 45-60%. However, the overall reported efficacy rating varied greatly depending on the study. An added benefit of occlusion was suggested (1 study), whereas no efficacy difference was established between different vehicles (2 studies). Three studies confirmed that weekend (or episodic) TCS treatment after achieving skin clearance was valuable to prevent plaque recurrence in 30-40% of patients at 6 months.

Since this publication, we identified 2 additional RCTs.^17,18 Desoximetasone 0.25% spray twice daily (BID) demonstrated statistically significant clinical success compared to the vehicle as measured by Physician Global Assessment (PGA) score 0/1 at 4 weeks (39% vs. 7%, respectively).¹⁷ Efficacy was better among compliant patients who received reminders compared to those that were not reminded, suggesting that compliance is an important barrier to treatment success.^18-20 Another RCT compared once daily (QD) halobetasol propionate 0.05% cream vs. halobetasol propionate 0.01% lotion suggesting similar efficacy at 2 weeks.²¹

Despite corticosteroid-sparing alternatives and combination therapies (discussed below) being commercially available, TCS remain widely used because of the low cost of some products as well as their versatility. They are available in a wide range of vehicles and potencies, ranging from I (ultra-high potency) to VII (low potency). Available vehicles include creams, lotions, foams, gels, ointments, shampoo, sprays, and solutions²² (Table 1). Typically, potent to ultra-potent TCS (class I-II) (e.g., clobetasol propionate) are used for thick plaques on the trunk/limbs or special sites, such as the scalp and palmoplantar regions; moderate potency TCS (class III-IV) (e.g., betamethasone valerate; triamcinolone acetonide) are suitable for thinner plaques on the trunk/limbs, whereas mild potency TCS (class VI-VII, e.g., desonide; hydrocortisone) are recommended for intertriginous areas, genitals and/or face.²² Milder potency preparations are also usually preferred to manage psoriasis in pediatric or pregnant patients.^23,24 The choice of the vehicle is made by the treating physician together with the patient. While some vehicles are preferred based on the anatomic site being treated and desired potency, patient preference is of utmost importance since this enhances treatment compliance. An RCT of vehicle preference among various TCS preparations assessed adherence to treatment and improvement of HRQoL among patients with psoriasis between spray, cream, ointment, gel, lotion, foam, and solution.²⁵ It was found that patient preference was highly variable, with less messy products favoured.²⁵ There was no overwhelming agreement on the effect of TCS vehicles in terms of efficacy, hence treatment should be individualized.

Table 1. Topical Corticosteroid Classes of Potency

Adverse events (AEs) with TCS use are generally rare, but may occur with prolonged and/or inappropriate use. These include local AEs such as skin atrophy, telangiectasia, striae, poor wound healing and infections. When used on the face or acne-prone skin, acne exacerbation or de novo periorificial dermatitis/folliculitis may occur.²⁶ Furthermore, even class VII TCS used on eyelids for prolonged periods can lead to cataracts and/or glaucoma.²⁷ Systemic AEs related to hypothalamic-pituitary axis (HPA) suppression are exceedingly rare.^28,29 Two systematic reviews/meta-analyses evaluated TCS safety in psoriasis. Literature identified was reassuring, with <5% risk of skin atrophy³⁰ and <5% rate of HPA suppression when TCS were used long-term.³¹ TCS withdrawal reactions, such as Red Skin Syndrome or topical steroid addiction, have also been reported with discontinuation of prolonged, frequent use of moderate to high potency TCS.³² These severe reactions are rare and are more likely to occur with use on special areas, such as the face and the genitals. A recent review article concluded that TCS are generally safe and effective when used correctly for short periods of time or with short breaks in longer treatments.³² Beside AEs, additional TCS related limitations include potential tachyphylaxis and corticophobia. Whether tachyphylaxis truly exists is debated among experts, as diminished efficacy over time may be related to low adherence to treatment among patients, especially when long-term treatment is required.³³ Corticophobia among patients and health care providers remains omnipresent and is a major barrier for treatment efficacy beyond inherent limitations associated with the drugs of this class.³⁴

Vitamin D3 Analogues

The introduction of Vitamin D3 analogues ~30 years ago was met with much enthusiasm due to their steroid-sparing effect.³⁵ Commercially available vitamin D3 analogues in Canada are calcipotriol and calcitriol ointments. Vitamin D3 analogues may be used as monotherapy, as an adjunct to TCS, or as fixed-dose combination therapy. They work by regulating gene transcription, modulating keratinocyte proliferation, and differentiation.³⁶ The mechanism of action also involves the inhibition of T cell proliferation and downstream inflammatory mediators.³⁶

There are several systematic reviews published assessing the efficacy of vitamin D3 analogues compared to vehicle or TCS.^37-41 As monotherapy, 1 review reported treatment success (defined as >90% reduction in the PASI score) with vitamin D3 analogues ranging from 4-40% after 6-12 weeks of therapy.³⁷ Another reported a decrease in the PASI ranging from 27.8-60.4% with calcipotriol monotherapy.³⁸ Further, BID use of vitamin D3 analogues was found to be at least as effective as TCS and more effective than placebo at 8 weeks.^38,39 A systematic review focused on efficacy of vitamin D3 analogues in pediatric psoriasis patients found 5 studies reporting improvement in PASI from baseline ranging from 17.3-94%, 1 study reporting improvement in Psoriasis Scalp Severity Index (PSSI) of 32.1%, and 1 study reporting 100% clearance of skin lesions.⁴⁰

In the last 10 years, only 2 new double-blind, vehicle-controlled phase III RCTs evaluated the efficacy and safety of calcipotriol 0.005% foam BID for mild-to-severe psoriasis (defined as plaque psoriasis involving 2-20% BSA) compared to vehicle.⁴² Both studies demonstrated significant treatment success, defined as the Investigator’s Static Global Assessment (ISGA) scores of 0/1 at 8 weeks. The primary outcome was achieved in 15% vs. 7% of calcipotriol vs. vehicle patients in the first study and 28% vs. 6% in the second study.⁴²

The use of vitamin D3 analogues in psoriasis has been shown to be safe and well-tolerated, with less AEs than TCS. AEs are generally comparable to the vehicle, with application site reactions occurring in less than 2% of subjects.⁴² Specifically, these include stinging, burning, and peeling of the skin.^37,43 Calcitriol may cause less irritation in sensitive areas compared to treatment with calcipotriol.⁴⁴ When used appropriately (maximum recommended dose of 100 g per week of calcipotriene or 200 g per week of calcitriol), the risk of hypercalcemia is very low.⁴³ Hypercalcemia risk was studied in 3 studies, occurring at a rate <1%.³⁷

Retinoids

Vitamin A and its naturally occurring and synthetic derivatives are referred to as retinoids.⁴⁵ They were introduced as a treatment for cutaneous disorders in the 1960s and, with the development of safer synthetic retinoids, have become widely used.⁴⁵ There are many topical retinoids used in dermatology, however, only tazarotene has been studied and indicated for psoriasis. While tazarotene lotion 0.045% is the only formulation commercially available in Canada, it is indicated for acne and used off-label for psoriasis. Tazarotene binds and modulates activity of retinoic acid receptors (RAR)-β and -γ, thereby decreasing inflammation and keratinocyte proliferation.⁴⁶

There were 2 systematic reviews assessing the efficacy of topical retinoids in psoriasis. The first contained 4 studies comparing tazarotene 0.05% or 0.1% gel or cream to placebo, finding tazarotene to be more effective in improving symptoms in the short-term (6-12 weeks).³⁹ However, the more recent systematic review comparing the same interventions found that symptom clearance as measured by Investigator’s Global Assessment (IGA) ranged from 5.5-6.2% with tazarotene 0.05% and 0.1% cream at 12 weeks, which was not better than placebo.⁴⁷ In the last 10 years, there have been no new published RCTs assessing the efficacy of topical retinoid monotherapy in psoriasis. Most clinical trials have focused on combination therapy of tazarotene and TCS.

The most common AEs associated with use of tazarotene are cutaneous local irritations such as peeling, erythema, itching, and burning at the site of application.⁴⁶ Cutaneous absorption of topical retinoids is limited, and there are no known systemic toxicities. However, as retinoids are teratogenic, women of childbearing age must use appropriate contraception.⁴⁶

Calcineurin Inhibitors (TCI)

Topical calcineurin inhibitors (TCI) have been approved since the early 2000s for the treatment of mild-to-moderate atopic dermatitis. While not indicated for psoriasis, TCI are often used off-label for facial and intertriginous psoriasis to avoid TCS-related AEs.⁴⁸ The available formulations are pimecrolimus 1% cream and tacrolimus 0.1% and 0.03% ointments. TCI bind to immunophilins, which lead to a decreased release of interleukin (IL)-2 and interferon (INF)-γ and thereby decreased T cell proliferation.⁴⁹

Systematic reviews assessing the efficacy of TCI for psoriasis confirmed tacrolimus superiority to placebo, TCS and calcitriol in treating facial and intertriginous psoriasis with treatment duration of 8 weeks.^50,51 However, pimecrolimus was inferior to standard psoriasis treatments.^50,52 One systematic review looked at the synergistic effect of TCI and TCS, which found that there was no additional benefit by combining these agents as opposed to TCS alone.⁵³

In the last 10 years, there have been 2 new RCTs published assessing the efficacy of TCI in psoriasis. The first studied the use of pimecrolimus 1% cream in the treatment of intertriginous psoriasis compared to placebo, finding that 71.4% in the treatment group reported an IGA of 0/1 at 8 weeks.⁵⁴ The second assessed tacrolimus 0.1% ointment in the treatment of nail psoriasis on 1 hand, using the other hand as a control. At 12 weeks, there was statistically significant improvement in the treated hand as evaluated by the Nail Psoriasis Severity Index (NAPSI) score.⁵⁵

AEs for topical TCI include skin irritation and discoloration to the site of application.⁵⁶ In 2006, a black box warning was issued for a potential link with skin cancer and lymphoma.⁵⁶ However, as a result of subsequent large-scale studies disproving this association,⁵⁷ Health Canada lifted the black box warning in 2021.⁵⁸ The systematic reviews and RCTs found similar rates of AEs between treatment and placebo groups,^51,54 however patients should be counselled regarding transient burning sensation when prescribed tacrolimus ointment to improve treatment adherence.

Tar

Historically, coal tar was considered a classic anti-psoriatic therapy and was used as a first-line agent for more than 2,000 years to treat psoriasis and other skin diseases.⁵⁹ Recent studies shed light into the mechanism of action of tar, suggesting modulation of epidermal differentiation and anti-inflammatory effects are likely achieved through activation of the aryl hydrocarbon receptor (AHR).⁵⁹ The efficacy of coal tar or its distillate, liquor carbonis detergens (LCD), in treating psoriasis was seldom formally evaluated. The limited available data suggests inferior efficacy to other commercially available agents. Specifically, a Cochrane Review (last updated in 2013), identified tar (including LCD) as generally less effective than TCS and vitamin D3 analogue monotherapies.⁴¹ Safety has been another important concern. As the “crude” word suggests, coal tar contains >10,000 organic compounds, including carcinogenic chemicals, such as benzene.⁵⁹ However, carcinogenic potential has not been proven.⁶⁰ Over-the-counter tar-containing products are available in different formats including lotions, creams, ointments, and shampoos, however, its application can be messy by staining hair, skin, nails, and clothing with a very unpleasant odour.⁶¹ While it can be compounded with TCS and other active ingredients to enhance effectiveness and penetration, currently it is primarily used in shampoos for the treatment of scalp psoriasis.⁶¹

Combination Therapies

Combination therapies were developed to improve treatment efficacy as it provides 2 mechanisms of action simultaneously and may have additive or synergistic effects.⁶² Further, they may decrease AEs related to each ingredient alone and are therefore better tolerated than monotherapy.⁶² Specifically, vitamin D3 analogues and retinoids decrease the risk of skin atrophy, whereas TCS decreases the irritation associated with vitamin D3 analogues and retinoids. Additionally, most fixed-dose combination topical therapies are prescribed to be applied QD as opposed to BID, thereby potentially improving long-term compliance. Commonly prescribed fixed-dose combination topical therapies include TCS and salicylic acid, TCS and vitamin D3 analogues (commercially available since 2001 as ointment, 2012 as gel, and 2016 as aerosol) as well as TCS and retinoids (commercially available as lotion since 2020).

Topical Corticosteroids and Keratolytics

Keratolytic agents, such as salicylic acid and urea, can improve the efficacy of TCS, especially for thicker plaques, by enhancing penetration and improving skin barrier. They are commercially available in combination as salicylic acid 3.0% and betamethasone dipropionate 0.05% ointment and salicylic acid 2.0% and betamethasone dipropionate 0.05% lotion. Additional alternatives can be compounded. There were several RCTs assessing combination therapy of salicylic acid and TCS showing superiority to monotherapy of either salicylic acid or the TCS alone.^53,63 However, 2 RCTs compared combination therapy of TCS and salicylic acid to calcipotriol monotherapy, with no clinical difference.⁶⁴ HRQoL was however improved with the combination therapy and was preferred by patients.⁶³ Only 1 RCT assessed urea in combination with TCS, which found a greater percentage of patients with an improved clinical score compared to monotherapy (47% vs. 33%).⁶³ Similarly, recent data showed that even simple moisturizers containing lipid-ceramides improve the efficacy of TCS.^65,66 In the last 10 years, there have been no newly published RCTs assessing the efficacy of topical salicylic acid and TCS combination therapy in psoriasis. Although rare, there is a risk of salicylic acid toxicity with topical application.⁶⁷

Calcipotriol and Betamethasone Dipropionate Fixed-Dose Combination

Calcipotriol 50 μg/g and betamethasone dipropionate 0.5 mg/g (Cal/BD), available in ointment, gel, and foam formulations in Canada, allows for both anti-inflammatory and anti-proliferative effects. A large Cochrane systematic review published in 2013 assessed the efficacy of combination therapies in psoriasis. Cal/BD was superior to placebo^41,68 and monotherapy (Cal or BD alone) in all but 1 RCT as early as after 2-8 weeks of treatment.⁴¹

In the last 10 years, there have been many new RCTs assessing the efficacy of Cal/BD for psoriasis focusing on the newer foam formulation, which when used QD for 4-12 weeks demonstrated a significant decrease in PASI from baseline of ~70%, superior to vehicle or either monotherapy.^69-72 Further, approximately half of participants achieved an IGA of 0/1.⁷³ Two studies compared Cal/BD to betamethasone valerate 0.1% dressing, showing in the first trial no significant efficacy difference at 4 weeks with Cal/BD ointment⁷⁴ and the second trial demonstrated superiority of the Cal/BD foam (at 4 weeks).⁷⁵ Several additional RCTs re-iterated the superiority of Cal/BD therapy vs. vitamin D3 analogue monotherapy.^76,70,77-80

Several RCTs focused on Cal/BD vehicle.^71,72,81 RCTs comparing different vehicles have shown better efficacy and superior HRQoL improvement with the use of Cal/BD foam compared to gel or ointment formulations^71,72,81 and cream compared to suspension.⁸² However, RCTs assessing vehicle preference as determined by patients did not find any significant preferences when comparing gel vs. foam, gel vs. ointment, and ointment vs. topical suspension, determining that individual patient preference should dictate treatment.^83-85 One real-world study found that patients using gel reported greater satisfaction compared to ointment due to ease of use.⁸⁶

One RCT focused on psoriasis relapse prevention following clinical clearance, defined as PGA score 0 or 1 (clear or almost clear).⁸⁷ In this study, both treatment arms received Cal/BD QD for 4 weeks initially to achieve skin clearance and were subsequently randomized into Cal/BD or vehicle biweekly as maintenance treatment. Patients that applied Cal/BD proactively experienced 3.1 relapses per year vs. 4.8 relapses (defined as PGA score 2 or higher) seen in the vehicle group. Median time to first relapse was also longer in the proactive management group (56 vs. 30 days) suggesting that proactive approach may be an interesting alternative to reactive approach for interested patients and could potentially be cost-effective.⁸⁷ As expected, both active treatment and proactive maintenance with Cal/BD were well-tolerated and no cases of skin atrophy were reported in either group.⁸⁷

Tazarotene and Halobetasol Fixed-Dose Combination

The only combination treatment of retinoid with TCS commercially available in Canada is halobetasol 0.01%/tazarotene 0.045% (HP/TAZ) lotion. A systematic review published in 2012 included 7 studies assessing the combination of retinoids (in general) with TCS, supporting superiority of combination as opposed to retinoid monotherapy at 4 weeks.⁸⁸ A recently published systematic review of 5 RCTs demonstrated treatment success, defined as at least 2-grade improvement from baseline in the IGA score and IGA score of 0 or 1 (clear or almost clear), of 32.8-52.5% for HP/TAZ compared to 33.3-34% for HP alone and 18.6% for TAZ alone with treatment duration of 2-8 weeks.⁸⁹

There have been several new RCTs published in the last 10 years assessing efficacy and safety of retinoids and TCS combination therapy. A combination tazarotene 0.05%/betamethasone diproprionate 0.05% (TAZ/BD) applied QD was superior to either agent used as monotherapy in 2 studies.^90,91 Treatment success of QD topical HP/TAZ lotion measured by the proportion of patients achieving IGA 0/1 ranged from 31.3-57.8% with treatment durations of 8-12 weeks,^92-99 which was significantly more effective than vehicle or either ingredient alone. The most frequent AEs reported were dermatitis, pruritus, pain, and irritation,^92,93,98 occurring in 6-20.8% of study participants.^91,97 A single RCT analyed the sensitization and irritation potential of HP/TAZ lotion with treatment duration of 4-6 weeks, finding that the topical did not induce contact sensitization and caused only minimal skin irritation, but significantly less than tazarotene alone.¹⁰⁰

Topical Therapies for Psoriasis – The Pipeline

As reviewed above, our current toolbox of topical therapy options is limited to TCS and a handful of other agents, such as vitamin D3 analogues, retinoids, tar or their combination. While the marketing of steroid-sparing monotherapies and fixed-dose combinations with TCS represents a major step forward in the management of psoriasis, these treatment options possess limitations in terms of efficacy, AEs, cost, patient satisfaction, and real-world adherence. Hence, there remains an unmet need for new topical therapies.¹⁰¹

There is an exciting topical therapy pipeline in psoriasis (Table 2), roflumilast and tapirnarof will be discussed in this section as phase III RCT data was recently published. Roflumilast is a phosphodiesterase-4 (PDE-4) inhibitor that has been developed into 0.3% cream and foam formulations. Crisaborole, a topical PDE-4 inhibitor, was approved in 2016 for atopic dermatitis in adults and children.¹⁰² Its use has been investigated for psoriasis in phase II RCTs, however, despite demonstrating efficacy and safety, results were not published. Rather, focus has shifted to roflumilast, a more potent PDE-4 inhibitor by 25-300X based on in vitro studies.¹⁰² PDE-4 inhibition suppresses the breakdown of cyclic adenosine monophosphate (cAMP), decreasing the presence of proinflammatory cytokines involved in the pathogenesis of psoriasis, similar to apremilast used systemically or topical crisaborole.¹⁰³ Phase I and II RCT data have demonstrated that roflumilast cream QD was superior to the vehicle when used for 2-8 weeks.^104-106 Phase III RCT data regarding roflumilast 0.3% cream efficacy and safety has been recently published.¹⁰⁷ DERMIS-1 and DERMIS-2 were parallel double-blind RCTs including 439 and 442 patients, respectively. Patients aged ≥2 years with psoriasis affecting 2-20% BSA were recruited and randomized 2:1 into either roflumilast 0.3% cream or vehicle applied QD for 8 weeks. The primary outcome was IGA 0/1 response plus ≥2 grade improvement from baseline, which was achieved in 37.5-42.4% of roflumilast-treated patients vs. 6.1-6.9% vehicle-treated patients. Improvement of PASI ≥75% from baseline (PASI75) was achieved in 39.0-41.6% vs. 5.3-7.6% of roflumilast-treated vs. vehicle-treated patients, respectively. It was also shown to be effective for the treatment of intertriginous psoriasis (68.1-71.2% vs. 13.8-18.5%). The incidence of AEs was comparable to the vehicle, with the most commonly reported events being diarrhea and headache in the roflumilast group. Further, AE profiles were similar in individuals aged 12–17 years relative to adults.¹⁰⁷ Currently, roflumilast is approved by the US Food and Drug Administration (FDA) and Health Canada.

Table 2. Topical antipsoriatic agents undergoing clinical trials

Tapinarof is an AHR-modulating agent that acts as an anti-inflammatory compound. It has a similar mechanism of action to tar, which also activates AHRs, however it does not contain carcinogenic chemical compounds.¹⁰⁸ Tapinarof is able to regulate innate and adaptive immune responses, affecting Th17 and regulatory T cells. It also has an important role in the development and maintenance of the skin barrier and upregulating barrier genes, such as filaggrin. Lastly, tapinarof inhibits the migration of T cells, decreasing the presence of proinflammatory cytokines, such as tumor necrosis factor (TNF)-α, INF-γ, IL-2, IL-13 and IL-17A.¹⁰³ Phase III RCT data has been recently published. In 2 parallel double-blind RCTs including >600 patients each, adults with mild-to-severe psoriasis (PGA 2-4, BSA 3-20%) were recruited and randomized 2:1 into either tapiranof 1% cream or vehicle applied QD for 12 weeks. The primary endpoint was IGA 0/1 and 2-point reduction from baseline at 12 weeks, which was achieved in 35.4-40.2% of tapinarof-treated patients vs. 6.0-6.3% of vehicle-treated patients.¹⁰⁹ While it was generally well-tolerated, increased rates of pruritus, contact dermatitis and folliculitis were seen in the active treatment group. A second RCT found that significantly more participants achieved a 75% reduction in the PASI score from baseline (PASI75) with tapinarof (50.4%) compared to calcipotriol (38.5%) and placebo (13.9%) when used QD for 12 weeks.¹¹⁰ Tapinarof has been recently approved by the FDA.

Treatment Guidelines for Topical Antipsoriatic Agents

Treatment guidelines for severe psoriasis and psoriatic arthritis are beyond the scope of this manuscript. This section will focus on reviewing guidelines specific to the treatment of mild-to-moderate psoriasis or treatment focused on topical agents.

Current guidelines for the treatment of mild-to-moderate psoriasis recommend topical therapies which include monotherapy with TCS, vitamin D3 analogues, TCI, retinoids, anthralin, and tar as well as combination therapies as first-line options. In Canada specifically, treatment guidelines were initially published in 2011. At this point, Grade A recommendation for first-line topical therapies included TCS or vitamin D3 analogues (i.e. calcipotriol) monotherapy or Cal/BD fixed-dose combination therapy. The treatment guidelines noted that additional topical therapy options were superior to placebo (e.g., retinoids alone or in combination with TCS, 15% LCD) and may be used on a case-by-case basis.^10,111 An update of these treatment guidelines was published in 2016 adding topical calcitriol as an additional first-line topical therapy option for mild psoriasis.^10,111

The American Academy of Dermatology (AAD) and National Psoriasis Foundation (NPF) have put forth the most recent guidelines in North America in 2020 focusing on topical therapies.¹⁴ The AAD-NPF guidelines do not mention specific recommendations for first-line topical therapy options, but rather provide guidance for use within each class. For TCS, Grade A recommendations include using class I to V agents for up to 4 weeks for body psoriasis (excluding intertriginous areas) and class I to VII agents for scalp psoriasis. The use of TCS for prolonged periods (>12 weeks) may be done under the supervision of a physician (Grade C). However, gradual reduction in frequency of TCS is suggested upon clinical improvement, but without defined tapering protocol. Following clinical improvement, maintenance of response can be achieved by using a steroid-sparing agent (e.g., vitamin D3 analogues or TCI) or by using TCS intermittently (e.g., biweekly, this is also known as proactive approach). Additional recommendations made in regards to TCS use were as follows: the use of emollient was suggested to reduce itching and desquamation and to prevent relapse after TCS discontinuation (Grade B). As well, topical salicylic acid alone or in combination with TCS was recommended as an alternative to TCS monotherapy to achieve clear skin (8-16 weeks of treatment, Grade B).

AAD/NPF guidelines recommended vitamin D3 analogue monotherapy and/or in combination with TCS (e.g., Cal/BD fixed-dose combinations) to induce clearance of scalp psoriasis (4-12 weeks treatment, Grade A), facial psoriasis (up to 8 weeks treatment, Grade B, caution to favour class VI-VII TCS agents) or body psoriasis (up to 52 weeks treatment, Grade A). Topical retinoids (e.g., tazarotene) were recommended either as monotherapy, fixed-dose combination (e.g., HP/Taz) or in combination with narrowband ultraviolet light phototherapy (NB-UVB) (Grade B) for plaque psoriasis and nail psoriasis. However, HP/Taz was preferred (Grade A) to induce clear skin (8-16 weeks treatment) due to better efficacy and tolerability.

The off-label use of TCI (e.g., tacrolimus and pimecrolimus) was recommended by AAD/NPF guidelines for facial and inverse psoriasis to achieve clinical improvement (Grade B recommendation) and to maintain response (Grade C recommendation). They also suggested a combination of tacrolimus/6% salicylic acid for body psoriasis (Grade B recommendation).

Grade B recommendation was also stated for short contact anthralin use (≤2 hours per day, up to 8-12 weeks treatment) and Goeckerman therapy (coal tar and NB-UVB) for mild-to-moderate plaque psoriasis.¹⁴ Coal tar preparations received Grade A recommendation as well.

Real-world Limitations with Topical Treatments and Strategies to Improve Compliance

As highlighted above, all current topical therapies come with limitations. Patient compliance is certainly among the most important barriers to success. Adherence rates with current topical therapies are low, estimated to range from 50-70% in general.¹⁰¹ The compliance rates for TCS are even more variable and in some instances are thought to be as low 8%, due to prevalent corticophobia among dermatology patients.^101,112 Adherence is an important concept that must be evaluated in patients as it is directly associated with better clinical outcomes. A recent RCT demonstrated that a decrease in adherence rate of 10% was associated with a 1-point increase in disease severity.¹¹³

Various interventions were studied to improve compliance. Three RCTs integrated reminders in the forms of BID telephone calls, text messages, or smartphone application to remind and motivate patients to use their topical therapy.^20,114,115 In all studies, adherence improved and almost doubled compared to non-interventional arms (65% vs. 38% adherence).¹¹⁵ This translated into significantly better clinical outcomes, such as reduction in PGA.^20,115 Another RCT developed a web-based application to educate patients with videos, graphics, and text.¹¹⁶ While knowledge was improved, this did not translate to increased treatment adherence.¹¹⁶ Four RCTs approached adherence by offering more clinical support, such as teaching from nursing staff or internet-based reporting.^117-120 Compared to standard of care, these clinical trials demonstrated that additional support resulted in greater clinical outcomes as early as 4 weeks, which were sustained at 3 months.^117-120

Vehicle selection is an important component of efficacy and adherence. Good vehicles can accelerate barrier restoration and enhance efficacy of active agents by promoting penetration and sustained drug release.¹²¹ As discussed above, RCTs assessing patient satisfaction have found that treatment preferences are heterogeneous and may even change over time.^83,122 Factors that may influence preferences included age, sex, comorbidities, disease duration, and prior treatments.¹²² Therefore, a vehicle should be selected to maximize efficacy and meet the diverse needs of the patient while considering bodily location of psoriasis, probability of improvement, and delivery method. An additional very important attribute for a topical therapy to improve patient adherence is convenience. While it may be patient-specific, an agent that does not need to be applied often (QD or less often), is universal (e.g., same product that can be applied anywhere on the skin), is cosmetically acceptable (texture, colour, and odour) and is affordable will likely promote higher patient adherence and thereby achieve better clinical success rates.

As discussed in the guideline review section above, the first aim of psoriasis treatment is to achieve clear/almost clear skin with a topical agent of choice (combined physician/patient decision for agent selection). Prior to fixed-dose combination topical therapies, in order to increase efficacy while mitigating AEs, different strategies were used. These included rotational treatment where patients alternated between 2 agents, usually a TCS and a corticosteroid-sparing molecule;¹²³ or a sequential treatment approach where a superpotent agent (usually TCS class I-II) was used initially with subsequent step down to either a milder TCS, steroid-sparing molecule or a rotational treatment. However, nowadays fixed-dose combination topical therapies are more popular for their additive efficacy, simplicity, and convenience.¹²³ Once acceptable control is achieved, discussion of relapse prevention is important.

Because psoriasis is chronic and likely to recur upon discontinuation of the topical therapy, it is important to educate the patient about the chronicity of the disease and its treatment at the initial and subsequent visits. Two approaches following initial improvement of psoriasis are commonly used in clinical practice to maintain response over longer-term: the proactive and reactive approaches. Combined physician-patient decision-making may opt for either a proactive approach which consists of using the same agent to achieve clear skin (or another topical) intermittently (e.g., biweekly) to psoriasis-prone areas in order to prevent recurrence, or a reactive approach where all treatments are discontinued upon clinical resolution and restarted promptly with first signs of disease recurrence.

Conclusion

The vast majority of our psoriasis patients have a mild-to-moderate disease requiring topical therapies life-long. Consequently, the availability of safe, effective, and convenient products is essential to achieve and maintain clear/almost clear skin and promote long term treatment adherence. In this review, we provided clinicians an up to date safety and efficacy data of commercially available topical products as well as imminent pipeline topicals. North American guidelines for topical treatment of mild-to-moderate psoriasis are summarized as well as clinical tips are provided.

¹Clinical Professor, Laval University, Quebec University Hospital Center, Hotel-Dieu of Quebec, Quebec, QC, Canada
²Dermatology resident, McGill University, Montreal, QC, Canada
³Medical Director and Principal Investigator, Dermatological Research Center of Metropolitan Quebec (CRDQ), Quebec, QC, Canada

Abstract

Drs. Joël Claveau & Julien Ringuet, two Canadian dermatologists with prominent clinical and research practices, attended the Les Journées Dermatologiques de Paris conference in Nov-Dec 2022, with a focus on presentations and posters about psoriasis. This article reviews key insights they obtained at the meeting. In brief:

• Psoriasis has a profound and multifaceted impact, but remains undertreated
• Progression to psoriatic arthritis is common; dermatologists can facilitate earlier detection
• The presence of comorbidities may inform the choice of biologic treatment
• New topical and systemic options enable treatment optimization for various subgroups
• Adverse effects of cancer immunotherapy include psoriasis, which requires treatment

PDF download available in English French

Psoriasis is a chronic inflammatory skin disease that affects an estimated 2% of people worldwide, with higher rates in Caucasian than Asian populations.¹ Plaque psoriasis is by far the most common form of the disease, accounting for about 90% of cases.¹ A relapsing condition with a wide range of severity, psoriasis often requires long-term therapy.¹

High Impact & Complex Comorbidities

The impact of psoriasis extends across all dimensions of life. The skin manifestations alone, which typically include thick, scaly and sometimes pruritic plaques, can significantly impact psychosocial well-being. Research has found that about 80% of patients feel embarrassment and shame, while 75% see themselves as unattractive and sexually undesirable.² A 2020 French study found that psoriasis also affected the quality of life and sexuality of patients’ life partners.³ In patients who develop psoriatic arthritis, inflamed joints, pain and fatigue can significantly impair mobility and occupational functioning.²

Now recognized as an immune-mediated inflammatory disorder, psoriasis extends to several other body systems.¹ Characteristic comorbidities are listed in Table 1.

Table 1: Comorbidities associated with psoriasis^4,5

Psoriatic arthritis, the most prevalent comorbidity of psoriasis, develops in about 30% of patients and appears about 10 years after the onset of psoriasis, on average.⁶ A heterogeneous disease, psoriatic arthritis may affect a few or many hand and foot joints (peripheral disease) and/or may involve the spine and sacroiliac joints (axial disease). Depending on how it is defined, axial involvement occurs in 25% to 70% of people with psoriatic arthritis.⁷

Presenters at the meeting emphasized that psoriatic arthritis develops along a “pathological continuum” that is often undetected. Indeed, about 15% of psoriasis patients followed by dermatologists have undiagnosed psoriatic arthritis.⁴ Dermatologists are in a unique position to identify early psoriatic arthritis. They should question their psoriasis patients about joint pain, stiffness, and search for signs of dactylitis and enthesitis. They could also consider referring patients for imaging and rheumatologic evaluation when deemed appropriate.^6,8

Treatment Trends & Unmet Needs

New advances in psoriasis treatment have raised the expectations and goals of treatment. Ninety-percent improvement in the Psoriasis Area Severity Index (PASI 90), or even PASI 100, has become a realistic treatment goal.⁹ The focus has also shifted toward absolute outcomes (e.g. PGA clear or almost clear).⁹ Efficacious treatments improve not only psoriasis symptoms, but also quality of life.² Treatment should be initiated early, especially when psoriatic arthritis is involved, to prevent disabling joint damage.⁸

Current medical treatment classes include topical agents (e.g. corticosteroids, vitamin A and D derivatives), traditional systemic agents (e.g. methotrexate, cyclosporine, acitretin), the oral phosphodiesterase-4 (PDE-4) inhibitor apremilast, and an expanding array of biologic agents (Table 2), sometimes recommended as first-line agents for moderate-to-severe plaque psoriasis.¹⁰ Historically, phototherapy (UVB and PUVA) was widely used to treat moderate to severe psoriasis, and narrow-band UVB phototherapy continues to be a good option for some patients.¹⁰

Table 2: Biologic agents used to treat psoriasis^11,12

Several presentations at the meeting focused on biologics that inhibit the IL-17 and IL-23 cytokine pathways. In patients with moderate-to-severe arthritis, high levels of these cytokines are associated with an increased risk of comorbidities.¹³ IL-17 and IL-23 inhibitors, which target psoriasis immunopathology and show an overall superior skin efficacy, have been gradually displacing anti-TNF agents and IL-12/23 inhibitors as first-line biologic options.^9,13 A meta-analysis of 44 studies established the overall safety and tolerability of IL-17 and IL-23 inhibitors.¹⁴ Common adverse events with these classes include infections, nasopharyngitis, and headaches,¹⁴ although the causality of these effects remains uncertain.

Despite the effectiveness of current treatments, psoriasis remains undertreated. In a 2019 online survey conducted in Germany, 59% of patients who received medical care for psoriasis were only moderately or less satisfied with their treatment.¹⁵ In the US, a study of registry patients found that, while most showed an “acceptable” treatment response after 6 and 12 months of systemic therapy, fewer than half reached their treatment targets.¹⁶ Clinicians are advised to optimize treatment in such patients. Effective strategies include increasing the dose, reducing the interval between treatments, or switching to another agent.⁹

Considerations in the Choice of Biologic Treatment

While both IL-17 and IL-23 are involved in the pathogenesis of psoriatic arthritis, IL-17-mediated inflammation may play a greater role in the development of axial disease and cardiometabolic comorbidities, while IL-23 may have greater involvement in the development of IBD.¹³ These distinctions can inform the choice between the two classes (Table 3).

Table 3: Choosing a biologic class based on comorbid PsA or IBD^8,11

Axial psoriatic arthritis: If patients require biologic therapy, anti-TNF agents are often used first-line, but IL-17 inhibitors are preferred if skin involvement is significant.⁷ In the MAXIMIZE study, over 60% of patients receiving the IL-17 inhibitor secukinumab showed an ASAS20 response at week 12, compared to 31% in the placebo group, and response was maintained through week 52.⁷ Drugs targeting the IL-12/23 pathway are not currently recommended due to a lack of studies showing clear efficacy⁷ as well as negative studies for ankylosing spondylitis.

Peripheral psoriatic arthritis: Evidence exists for all classes of biologics used to treat psoriasis, as well as for the PDE-4 inhibitor apremilast.⁸ The JAK inhibitors tofacitinib and upadacitinib have also shown efficacy and are approved for this indication.

Inflammatory bowel disease: For psoriasis with comorbid IBD, positive data exist for the use of anti-TNF inhibitors, the IL-12/23 inhibitor ustekinumab, and IL-23 inhibitors.¹¹ Of note, Health Canada approved the IL-23 inhibitor risankizumab for Crohn’s disease in late 2022. On the other hand, the IL-17 inhibitors secukinumab and brodalumab have failed studies in Crohn’s disease.¹¹ Cases of new-onset IBD have been observed in psoriasis patients treated with IL-17 inhibitors, though the signal is low and these cases may arise from the disease process itself, rather than as an outcome of IL-17 inhibition.¹¹

Speed of onset of action has become an important differentiator among systemic treatments, as patients place high value on rapid clearance.⁹ Dosing regimen also comes into play, with many patients showing a preference for less frequent administration.

Oral candidiasis, a rare side effect related to the mechanism of action of IL-17 inhibition, generally responds to treatment and is not a reason for discontinuing the biologic.¹¹ Reported cases of suicidality with brodalumab have led to further investigations; to date, a causal relationship has not been established.¹¹

New Molecules

Several new practice-changing molecules were introduced at the meeting. Topical tapinarof, a hydrocarbon receptor-modulating agent, has been investigated for both psoriasis and atopic dermatitis and is expected to enter the Canadian market soon. In two Phase 3 PSOARING trials, a Physician Global Assessment (PGA) response occurred at week 12 in 35.4% and 40.2% of patients treated with tapinarof, respectively, compared to 6.0% and 6.3% in the vehicle groups.¹⁷ Of note, 58% of the patients who did not achieve PGA-0 or PGA-1 at week 12 reached this outcome at week 52 in the open-label extension study.¹⁸ In patients who reached PGA-0, the median duration of remission after discontinuation of treatment was 130 days.¹⁸ A second new topical agent, a potent PDE-4 inhibitor called roflumilast, showed similar results in the DERMIS 1 and 2 trials: at week 8, 42.4% and 37.5% reached the Investigator Global Assessment (IGA) endpoint in the active treatment groups, respectively, versus 6.1% and 6.9% in the control arms.¹⁹ A distinctive feature of this agent is its efficacy and tolerability in special sites such as facial, genital and intertriginous areas.

Deucravacitinib is a new oral JAK inhibitor that specifically targets the TYK2 receptor, which differentiates it from less targeted JAK inhibitors. As shown in the Phase 3 POETYK-1 and -2 trials, the molecule is potent enough to treat moderate-to-severe psoriasis. In the trials, 53-58% of patients in the treatment arms reached the co-primary endpoint of PASI 75, compared to 35-40% in comparator apremalist arms and 9-12% in the control arms.²⁰ Corresponding results for the other co-primary endpoint (IGA 0-1) were 50-53% for deucravacitinib, 32-34% for apremilast, and 7-8% for placebo.²⁰ Longer-term data showed that efficacy was maintained for up to 52 weeks. These results led Health Canada to approve this agent in late 2022.

Deucravacitinib has also been investigated for psoriatic arthritis in a recently published Phase 2 study.²¹ Patients were randomized to receive placebo or one of two doses (6 mg and 12 mg daily) of deucravacitinib, with ACR-20 response at week 16 as the primary endpoint. Response was significantly higher with deucravacitinib 6 mg (52.9%) and 12 mg (62.7%) than with placebo (31.8%),²¹ suggesting this oral agent may play a role in the treatment of psoriatic arthritis. Phase 3 studies are ongoing.

A first-in-class biologic called spesolimab, which targets the IL-36 receptor, has recently been approved by the FDA for the treatment of generalized pustular psoriasis (GPP), a severe form of psoriasis that causes pustules on an erythematous base often associated with systemic symptoms. In the Phase 2 trial of patients with severe GPP, spesolimab 900mg IV demonstrated clear superiority over placebo (54% vs. 6%) for the main outcome measure of GPPGA-0.²² [GPPGA = Generalized Pustular Psoriasis Physician Global Assessment.] Serious adverse events were reported in 6% of patients on spesolimab versus 0% on placebo, and a signal of infectious risk also emerged in the spesolimab group. The ongoing Effisayil 2 trial is evaluating spesolimab as maintenance treatment for GPP.²³

Cancer Immunotherapy and Psoriasis

The meeting helped raise awareness of an increasing challenge in dermatology: the management of adverse events induced by cancer immunotherapy. Immune checkpoint inhibitors (ICIs) represent a significant leap in cancer treatment, but they come at the cost of various immune-related adverse events, including dermatologic adverse events in about 40% of cases.²⁴ In a multi-centre study of patients on ICI therapy, psoriasis accounted for 23% of skin-related side effects.²⁵ While most ICI-induced psoriasis is the plaque subtype, all other subtypes have been reported.²⁴ Other common dermatologic sequelae of ICI treatment include lichenoid and eczematous eruptions, pruritus, and vitiligo.

Figure 1: Checkpoint inhibitor-induced psoriasis

ICI treatment can induce psoriasis de novo or cause preexisting psoriasis to flare up.²⁴ This can complicate treatment decisions and underscores the need for oncologists to consult dermatologists when treating patients with a history of psoriasis or psoriatic arthritis, including during flareups.

On a positive note, the presence of skin toxicities may signal that ICI treatment is working. In a population-level cohort study that reviewed a database of over 200 European and US patients treated with ICI, the development of cutaneous adverse events was strongly associated with therapeutic response and patient survival.²⁶ If more severe ICI-induced skin toxicities are not managed, however, they may compromise the therapeutic outcome of cancer treatment.²⁵

For moderate cases of CI-induced psoriasis, acitretin, methotrexate, and/or apremilast are deemed suitable options.²⁴ For more severe presentations, the EADV task force “Dermatology for Cancer Patients” recommends reinforcing therapy for moderate disease (including dose optimization) and consideration of anti-TNF and IL-23-targeting biologics in non-responders.²⁴ The paper also advises avoiding IL-17-targeting agents due to their gastrointestinal effects,²⁴ though this is still a subject of debate. Ideally, ICI treatment should be discontinued until the psoriasis improves to grade 0 or 1.²⁴

Overall, the management of ICI-induced dermatologic adverse events requires a balance between reducing troubling skin toxicities that compromise patients’ quality of life and preserving the benefits of cancer treatment.

Conclusions

The global medical community has come to understand psoriasis as a systemic disease with a profound impact. The optimal treatment choice depends not only on the disease subtype and severity, but on a patient’s comorbidity profile. While both systemic and topical treatments continue to improve, many patients remain undertreated. Dermatologists can play a significant role in detecting emergent psoriatic arthritis and in managing psoriasis induced by cancer treatment.

Test Your Knowledge

Question 1: Which class of biologic is not suitable for psoriasis patients with comorbid inflammatory bowel disease, and why?

Question 2: If patients on cancer immunotherapy develop psoriasis, should they be switched to a different cancer treatment?

Charles W Lynde MD, FRCPC¹, James Bergman MD, FRCPC², Loretta Fiorillo MD³, Lyn Guenther MD, FRCPC⁴, Marissa Joseph MD, FRCPC, FAAD⁵, Jill Keddy-Grant MD⁶, Ian Landells MD, FRCPC⁷, Danielle Marcoux MD, FRCPC⁸, Catherine McCuaig MD, FRCPC⁹, Michele Ramien MD¹⁰, Wingfield Rehmus MD MPH FAAD¹¹

Introduction

Atopic dermatitis (AD) is a lifelong pruritic, inflammatory skin disease associated with altered immune function and epidermal barrier dysfunction.^1-3 The chronic and recurring cyclic waxing and waning nature of AD leads the patient to treatment fatigue and imposes a significant burden on both the patients’ and caregivers’ quality of life (QoL).¹ AD frequently appears early in childhood and affects over 20% of children and up to 3.5% of adults.^2,3 Measurements of the prevalence of AD can differ, and this variability can be impacted by geographic location, population studied, and definition of AD used. A Canadian study showed that the adult prevalence of AD is up to 3.5% and that AD may be more prevalent among First Nations populations.² This research further revealed that men were less affected than women and that AD decreases with age. Additionally, the study noted that the severity of AD varies per region.² In many countries, the prevalence of AD is on the rise, especially in young children from developing lower-income countries in South East Asia and Latin America.⁴ Although the role of race and ethnicity in the pathophysiology of AD remains unclear, a higher incidence of AD was observed in Black American children (17.3%) compared to White children (10.4%).⁴

The pathophysiology includes skin barrier defects, inflammatory cytokines, and immune abnormalities. ADs’ etiology is multifactorial and involves an incompletely understood interaction between genetic factors, immune system dysfunction, skin barrier disorders, genetic and environmental stressors.^5,6 Most of the patients with AD have mild disease; however, 10% – 20% of children with AD are categorized as severe, and these rates are slightly higher in adults.²

There is a need for a variety of therapeutics targeted to different levels of severity.^6,7 A treatment paradigm that recognizes that patients may oscillate between degrees of severity and integrates topical and systemic therapies may align more closely with clinical reality.^8,9 AD treatment is often challenging due to the disease itself, treatment fatigue, and patient/caregiver concerns. Patients and caregivers frequently have concerns about medication safety and adverse events (AEs) as well as the long-term use of topical corticosteroids (TCS) or topical calcineurin inhibitors (TCI).⁹ Crisaborole ointment is an effective and safe alternative to TCS and TCI.⁹ Sharing best clinical practice standards, addressing challenges in treatment application, and methods to improve patient adherence to therapy may improve treatment results.⁹

This paper aims to review best clinical practices in treating AD patients, explore optimal use of crisaborole in mild to moderate disease, and provide expert guidance for the real-world use of crisaborole ointment to improve patient outcomes. This papers’ target audience is general practitioners, pediatricians, pediatric dermatologists, and dermatologists who treat patients with AD.

Methods

The project used a modified Delphi communication technique for interactive decision-making for medical projects, adapted from face-to-face meetings to suit a virtual platform.^10-12 The meeting was virtually convened on May 8, 2021, and the expert panel consisted of eleven dermatologists, including nine pediatric dermatologists from diverse geographical regions within Canada, who commonly treat patients with AD. In preparation for the meeting, a literature review surrounding crisaborole for the treatment of mild-moderate AD was conducted, and the panel members were surveyed regarding the use of crisaborole ointment for the treatment of AD.

The literature review and the pre-meeting survey results were presented at the virtual meeting. During the meeting, the experts were divided into three breakout groups to discuss and adopt draft recommendations for the real-world use of crisaborole ointment that were prepared from the literature searches by CWL and AA. The three groups presented their adapted versions of the recommendations to the larger group following the breakout session. The adapted recommendations were then collated and edited if necessary. The panel then voted and adopted the recommendations using evidence coupled with expert opinion based on the clinical experience of the advisors. The meeting summary and subsequent review of the manuscript were performed online (Figure 1).

Literature Review

Searches for English-language literature [2015– 2020] took place on April 14, 2021, on PubMed and Google Scholar as a secondary source. The data gathered by the literature review prioritized clinical studies published on the use of crisaborole, articles describing the current best practice in AD, and the most recent clinical guidelines, consensus papers and, algorithms. Excluded were duplications, articles of insufficient quality [small sample size, flawed methodology], and the most recent reviews were used in the case of review articles.

The searches yielded sixty-two papers deemed clinically relevant to current best practices of crisaborole use in AD. After removing duplicates and articles of insufficient quality, thirty publications remained: Four on epidemiology, ten reviews, three consensus papers and algorithms, four guidelines, five clinical studies, and four systematic reviews, meta-analyses, or posthoc analyses.

Results

The literature review indicated that the guidelines, algorithms, and consensus papers for topical AD treatment had not changed significantly over the past decade apart from adding crisaborole ointment and removing the black box for topical calcineurin inhibitor (TCI) treatment.^{7-9, 13-21}

A consensus paper and algorithm that explored the need for practical solutions to improve AD care was developed and published by the authors’ panel.⁸ The consensus statements and algorithm for topical treatment and maintenance of AD were integrated into the panels’ recommendations presented in this publication.

The DERMA (D: Diagnosis/Distribution; E: Education/Emollients; R: Red/Itchy; M: Medication/Maintenance; A: Assessment /Adherence) AD Algorithm targets a broad base of health care professionals treating patients with AD. The consensus statements and DERMA AD algorithm for topical treatment and maintenance of AD reflected current practice and were integrated into the panels’ recommendations (Figure 2).

Clinical Evidence of Crisaborole

Crisaborole is a small molecule, anti-inflammatory nonsteroidal PDE4-I inhibitor for the treatment of AD, which has demonstrated safety and efficacy in patients with mild-to-moderate AD.^22-30 Two percent crisaborole ointment was first approved by the American Food and Drug Administration (FDA) in December 2016 and then in 2018 by Health Canada for mild-to-moderate AD patients aged 2 years and over and in March 2020 (USA) and May 2021 (Canada) for patients aged 3 months and over.²⁵

The efficacy and safety studies on crisaborole used various clinical assessment scales such as Investigator Static Global Assessment (ISGA), Atopic Dermatitis Severity Index (ADSI), Eczema Area, and Severity Index (EASI) score, and Patient-Oriented Eczema Measure (POEM).

A randomized, double-blind, intra-patient controlled study (for the first 14 days) was continued as an open-label study applying crisaborole to all lesions. The study, including 40 patients of 18 years-old and older, demonstrated significant changes from baseline in crisaborole-treated lesions, ISGA, and pruritus NRS improvement from day fifteen assessment onwards.²³ The study also showed normalization of the genomic skin profile (approximated normal skin), inhibition of inflammatory genes known to be induced through degradation of cAMP by PDE4, and reduction in epidermal hyperplasia and TEWL.²³

The safety and efficacy of crisaborole treatment over 28 days were shown in two identical randomized, double-blind, vehicle-controlled studies including 1,522 patients with mild-to-moderate AD of 2 years and over.²² Significantly more patients treated with crisaborole than vehicle reached the primary endpoint (ISGA: clear, almost clear) than those treated with the vehicle at day 29 assessment.²² A long-term, open-label, single-arm 48 weeks safety study that included 517 patients of 2 years and over showed similar safety results as in a previous study that included adult AD patients.^22,24 In the long-term open-label study, nine patients (1.7%) withdrew due to AEs such as a stinging sensation after applying the ointment.²⁴ Another phase four open-label, single-arm study on 137 infants aged 3 months to less than 24 months of age demonstrated that crisaborole is safe and effective. ISGA of clear or almost clear was achieved at day 29 assessment by 30.2% of patients.²⁵ The study further indicated that improvements exceeded the minimal clinically significant difference in total POEM score at day eight and day twenty-nine.²⁵ The POEM subscale data further revealed improved sleep and pruritus, markedly improving patients’ and their caregivers’ quality of life.²⁵ Crisaborole yielded a rapid and statistically significant reduction in pruritus within four days.^26-28 Notably, in two vehicle-controlled studies, the vehicle effect on pruritus was considerable.^26,28

A pooled analysis of four studies of mild-to-moderate AD patients demonstrated efficacy and local tolerability of crisaborole treatment. After crisaborole use, most patients had mild to no pruritus from the first assessment through the remainder of treatment.²⁷

In a further study, treatment with crisaborole resulted in a marked improvement in QoL for patients and their parents, caregivers, and families.²⁸

A post hoc analysis of 2 phase 3 studies showed the effectiveness of crisaborole compared to the vehicle in significantly alleviating mild-to-moderate AD severity (per ADSI), and percentage of body surface area (%BSA) affected.²⁹

Finally, a systematic literature review and network meta-analysis comparing efficacy and safety profiles of crisaborole ointment, 2%, versus other topical treatments for mild-to-moderate AD showed crisaborole was superior to vehicle and pimecrolimus 1% cream, and comparable to tacrolimus, 0.1% or 0.03% ointments, concerning ISGA 0/1 at 28-42 days.³⁰ Additionally, the systematic review showed that the AEs rates for application site burning/stinging were much higher for TCIs than for crisaborole.³⁰ The studies included different patients, and endpoints varied, so comparative assessment of medications from this meta-analysis is difficult. Head to head comparative studies are needed to see objective scientifically-grounded efficacy comparison.

Crisaborole works better for mild than moderate disease, where it provides a faster reduction of pruritus and other AD symptoms relieve.^9,25-30 Crisaborole is not typically used with TCI due to potential irritation, but the combination may be suitable for steroid-phobic patients and those at high risk of sequelae.⁹

It is advisable to avoid crisaborole application on significantly flared skin due to possible irritation. Crisaborole ointment can be beneficial for dermatitis of the hands and feet due to the potential for deeper penetration into inflamed, thicker lichenified skin as a result of the smaller molecular size of crisaborole. There appears to be less irritation of the hands and feet, and the good safety profile of crisaborole justifies application in infants and children.^9,25-30

Statements and Recommendations

Statement 1: Atopic dermatitis (AD) is a lifelong inflammatory skin condition associated with epidermal barrier dysfunction and altered immune function. When AD is not controlled by behavioral measures such as skincare and avoidance of triggers, treatments such as TCS, TCI, and more recently, PDE4-I should be considered. It is important to use topical agents in conjunction with moisturizers and gentle cleansers.

The complex multifactorial pathogenesis of AD includes genetic and environmental factors.⁵ The skin barrier in AD is dysfunctional, and this defective skin barrier leads to water loss from the skin and the ingress of irritants, pathogens and allergens resulting in further inflammation.⁷ As the dysfunctional barrier at baseline is further disrupted, an inflammatory immune response is upregulated, which further disrupts the barrier leading to a feedback loop.^6,31,5,6

AD presents clinically as recurrent scaly erythematous and pruritic papules and plaques of skin with varying severity. This morphology, in addition to pruritus and family history of atopy, are important diagnostic criteria.^7,32 Specific signs of AD include oozing, scaling, crusting, erythema, edema, and lichenification, which, together with the body surface area involved and the impairment of daily activities, help determine AD severity (Figure 3-5).
Most patients with AD present with mild disease and can be adequately treated with frequent moisturization and topical therapy such as TCS, TCI, or crisaborole.^{3,5,7,8,12-21}

Educating patients and caregivers about the condition, avoiding triggers, and daily skincare regime, including gentle cleansers and moisturizers, is a vital part of the approach.^{7-9, 13-21}

AD is a chronic disease, and as a result, adherence to therapy is a major obstacle. Education and patient support and can improve adherence and, in turn, outcomes. It is important to remember that AD education is not a one-and-done phenomenon. Ongoing reinforcement of the treatment plan and goals is needed. Clinicians need to explain the condition, the rationale for treatment, optimal treatment use, and demonstrate the application process in their office.^8,9 During the detailed conversation, solicit the patients’ or caregivers’ input and questions to enable their active role in the process.⁹ This will help manage expectations, adherence to treatment, and maintenance of the lifelong chronic disease.⁹ Actions to improve patient adherence with treatment include detailed but easy to follow information and options to revisit the information by reading materials or trusted websites (Box 1).^8,9,15,19

Box 1: Patient and caregivers information and education about crisaborole

Statement 2: Crisaborole, 1% ointment, is a nonsteroidal anti-inflammatory PDE4-I with demonstrated efficacy in patients aged three months and older with mild to moderate AD. It is a well-tolerated alternative to TCS or TCI and can be used on any body site. It may be especially beneficial for:

• Sensitive areas prone to thinning from TCS such as the face, intertriginous areas, and genitals
• Hand, feet, palms, and soles, where the small molecular size may allow potential deeper penetration

A previous publication by the panel reviewed various cases that reflect real-world clinical use of crisaborole aimed to clarify its optimal use as monotherapy, combination therapy, sequential therapy, and maintenance therapy.⁹ Crisaborole can provide a good and safe alternative to TCS and TCI, such as in cases of steroid or TCI avoidance, and can be used in mild-to-moderate AD patients from 3 months of age upwards.²⁵

The case studies discussed in the article suggested that crisaborole treatment was effective and well-tolerated for pediatric AD of the face, hands, and feet of infants, toddlers, young children, and adults where therapy with TCS or TCI had failed.⁹ One of the cases was a 5-year-old boy with moderate-to-severe AD of his hands that was painful and severely impacting daily activities, such as playing and interacting with other children. After eight weeks of crisaborole use, his hand palms and wrists involvement had almost entirely cleared.⁹

The advisors recommend that the smaller molecular size of crisaborole may allow better penetration into the skin to the site of inflammation.⁹ The advisors also indicated that there might be a cumulative effect of adding crisaborole for hands and feet that can benefit from its optimal penetration as part of a combination regimen with TCS and TCI in moderate-to-severe AD cases.⁹

Statement 3: Crisaborole may be used as a first-line topical agent and is also a good choice when previous treatment has yielded suboptimal results when TCS side effects constitute a significant concern, and in the case of TCS/TCI phobia.

TCS and TCI hesitancy exists among all cultures and likely contribute to AD treatment failure.³³ Widely available biased unreliable, and inaccurate sources of information about eczema and topical therapies such as TCS and TCI are not helpful for AD patients and hinder physicians ability to educate and treat appropriately.³³ Clinicians must inquire about and if present must thoroughly discuss the patients and caregivers’ concerns about TCS and TCI and emphasize that these treatments are vital and, if used appropriately, safe and effective.^{5,7,8,9,12-21} Providing the patient with trusted websites can give balanced information, thus addressing the issues that are adding to patients concerns, especially in those with TCS and TCI phobia.^15,19

If patients or caregivers continue to have safety concerns surrounding TCS/TCI treatment, then crisaborole can offer a safe alternative even in infants as young as three months of age.²⁵ In this situation, offering a safe and effective alternative to TCS or TCI may improve treatment adherence and patient outcomes.⁹

Statement 4: When starting topical therapies such as crisaborole, consider the following:

• Test the patients’ tolerability with a sample before a prescription to determine the degree of stinging
• Avoid its initial use on severely inflamed or open areas of skin
• Limit its use to areas less likely to sting/burn
• Use the product in combination with a refrigerated moisturizer

The recommendations are supported by the advisors’ clinical experience⁹, a post hoc analysis of 2 phase 3 studies²⁹, and a systematic literature review comparing efficacy and safety profiles of crisaborole and other topical treatments in mild-to-moderate AD.³⁰ Crisaborole is used in mild-to-moderate AD, but it is best to avoid application on severely inflamed and open areas if possible to minimize stinging.^29,30

Testing the patients’ tolerability in-office before prescribing crisaborole provides an opportunity to teach the patient about the appropriate application of the medication and identifies the uncommon patient who has more prominent stinging and thus may not tolerate the medication. The application also helps to identify the patient who has mild discomfort. Proper education and guidance can minimize the symptoms and allow then to get past the short-term symptom. Application in the office and identifying these subgroups will instill greater confidence in the medication and make it more likely that the prescription will be filled and utilized rather than abandoned after one application.

Improved knowledge about the central roles a defective skin barrier and dry skin may play in AD increasingly recognizes the benefits of daily and ongoing use of mild cleansers and moisturizers.³⁴ The use of a gentle cleanser that employs advanced vehicles with a near-physiologic pH (4.0–6.0) may help maintain skin barrier function by optimizing skin surface pH levels.³⁴ Utilizing moisturizers to optimize the barrier decreases water loss, decreases inflammation, and improves the skin’s barrier and natural moisturizing factors. Moisturizers that contain skin lipids such as ceramides have shown benefits over standard emollients when used for AD patients.³⁵

In an algorithm for South and East Asian AD patients, moisturizers were included as a standard measure when using topical treatments for AD, such as pimecrolimus.³⁶ A refrigerated moisturizer used in combination with crisaborole ointment may prevent irritation, burning, or stinging.⁹

Statement 5: TCS, TCIs, and PDE4-I may induce application site pain such as burning and stinging. Information and education on measures to prevent or treat these side-effects, such as testing/limiting application sites and concomitant use of a refrigerated moisturizer, can help optimize results and decrease skin irritation.

Few AEs such as irritation, burning, and stinging were reported in clinical studies using crisaborole but seem to be occurring more frequently in clinical practice.^16,9

Clinical trials report stinging or burning occurring in up to 8%, but the symptoms are usually transient, and 1.7% of patients withdrew due to these symptoms. In practice, clinicians have anecdotally noted that the rate of stinging seems to be greater than that reported in clinical trials, but generally, the stinging is mild and transient.^16,9 Topical medications can sting due to the stabilizers and preservatives in the vehicle cream or due to the medication itself. TCIs can sting, and this stinging is often correlated to the degree of inflammation in the area. Clinicians often apply TCS initially to calm down the AD, after which the TCI is better tolerated. Whether this technique applies to crisaborole is not clear but should be answered by future reports/ studies.^8,9

Before starting crisaborole therapy, inform and educate the patient and caregiver on measures that may prevent or quickly resolve irritation, burning, or stinging if it occurs.⁹ Best practice tips of the panel include the use of crisaborole with daily skincare, such as a gentle cleanser and a refrigerated moisturizer.⁹ Apply a patient age-appropriate regimen and patient education.⁹ Identifying patients prone to skin irritation may benefit from an in-office trial with a sample before prescribing the ointment.

Survey Results

A pre-meeting survey was conducted among the panel to share best practice standards and clinical pearls they use in prescribing crisaborole to mild-to-moderate AD patients. All eleven advisors completed the survey. Demographics, number of visits of AD patients, the severity of AD, and treatment are shown in Table 1. When asked: If Crisaborole is not your first choice, indicate why not? stinging (63% [7]), burning (40% [4]) and costs (91% [10]) were frequently mentioned. Six physicians also answered crisaborole was not used for other reasons, which included: Lack of payer coverage, Need to be off-flare to initiate the treatment to get a good response, It is not as effective and does not work as quickly as TCS or TCI, Other medications are effective and more readily available and with which there is more clinical experience. The advisors noted to specifically use crisaborole for various body locations such as the face (72% [8]), hands (91% [10]), eyelids (55% [6]), intertriginous areas (63% [7]), genitals (63% [7]), and feet (81% [9]). According to the advisors, they hypothesize that the small molecular size of crisaborole appears to allow better penetration on areas with thicker skin.

Table 1: Pre-meeting survey results
N=11
Topical corticosteroid (TCS), atopic dermatitis (AD)

When asked the main reasons to prescribe crisaborole, all (100% [11]) answered that there is a need for a nonsteroidal alternative. Other answers included TCS phobia (91% [10]) and TCI phobia (63% [7]) and suboptimal results with previous therapy (63% [7]).

When stinging or burning occurred with crisaborole use, the advisors discontinued the treatment more frequently in children than adults. For preventing and managing AEs, the advisors provided education before starting crisaborole treatment. Some tested patients’ tolerability to the treatment in the office prior to a prescription to determine the degree of stinging. Further, they recommended measures to reduce stinging, such as concomitant use of a gentle cleanser and refrigerated moisturizer, cooling the ointment in the fridge, and concomitant TCS or TCI use (Figure 6). Finally, the advisors agreed to avoid the application of crisaborole on severely flaring skin.

When asked about the patients’ response to crisaborole treatment within four weeks, forty percent of responders noted that on average, 20-50% of patients had improved, and 50% of the panel noted an improvement in over 50% of their patients (Figure 7 and 8).

Limitations

Measures to reduce burning and stinging that may occur when using crisaborole were developed using the authors’ expert opinion and clinical experience, and further studies are needed to support the possible benefits of these measures.

Conclusions

The review explored best clinical practices of crisaborole for mild to moderate AD patients and provided expert guidance for the real-world use of crisaborole ointment.

Atopic dermatitis is a common chronic inflammatory disorder in which patients experience a waxing and waning disease state that is punctuated by episodes of flares. If their disease is quiescent, then the patient continues good skincare by utilizing moisturizers and avoiding irritants. Patients will escalate and add topical medications at the first sign of a flare. Since every patient has a distinct disease course, some patients may never be fully clear while others clear between episodes. Recognition that patients with AD have a disease that often varies in severity and location on their body allows physicians to choose the appropriate treatments based on their clinical experience. The physician needs to educate their patient to escalate therapy accordingly at the first sign of disease in order to prevent severe flares. An eczema treatment plan is a necessity to ensure a smooth transition of therapy from baseline to flare. For mild to moderate AD patients, three topical options can be prescribed to control inflammation. Traditionally these medications have been divided into first and second-line therapy. However, the expert panel believes that the choice of a specific agent should be decided by the clinician based on factors such as disease severity, location, physician experience with the product, cost, and patient preference.

Crisaborole is a nonsteroidal PDE4-I with demonstrated safety and efficacy in patients aged three months and older with mild to moderate AD. It is a well-tolerated alternative to TCS or TCI and can be used on any cutaneous non-mucosal body site. It may be especially beneficial for areas with thicker skin, such as hands and feet, possibly due to improved penetration to the site of inflammation as a result of its small molecular size. There are no concerning serious safety signals associated with crisaborole. Crisaborole does cause a burning sensation in 8% of patients, but this is usually transient and may be minimized by the concomitant application of cool moisturizers. Consideration of in-clinic test site application of crisaborole to high-risk individuals may help identify those at risk and allow patient education, which may decrease the side effect and in turn improve adherence and outcome.

¹Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
²Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada
³Department of Dermatology and Skin Science, University of British Columbia, Vancouver, BC, Canada

Conflict of interest:
Joseph Lam has served as an advisory board member for Bausch Health, Leo Pharma, Pfizer Canada and Sanofi-Genzyme.
He is on the speaker’s bureau for Pfizer Canada. He has received a research grant from the Eczema Society of Canada. Aryan Riahi has no conflicts to declare.

Abstract:
Atopic dermatitis (AD) is a chronic, relapsing, inflammatory condition marked by pruritus and traditionally treated with topical corticosteroids (TCS) and topical calcineurin inhibitors (TCI). Crisaborole 2% ointment (a topical phosphodiesterase-4 inhibitor) is a newer topical agent for the treatment of AD. Crisaborole is indicated for treating mild-to-moderate AD and evidence from phase 3 and phase 4 trials show that crisaborole is an effective agent with a well-tolerated side effect profile for children >2 years of age. The most common side effects are pain and paresthesia at the application site. Treatments with tolerable safety profiles such as crisaborole may provide an alternative to patients with TCS phobia. The role of crisaborole in AD therapy may become clearer as multiple phase 4 trials are currently underway and their results are poised to answer more questions, including its safety profile for patients as young as 3 months of age, potential use as a steroid-sparing agent, and direct comparisons to TCS and TCI, which are the current mainstay treatments of mild-to-moderate AD.

Key Words:
crisaborole, Eucrisa, atopic dermatitis, eczema, topical treatment, phosphodiesterase-4 inhibitor, corticosteroids

Introduction

Atopic dermatitis (AD) is a chronic, relapsing, and inflammatory condition affecting the skin. Clinical features include xerosis, oozing, crusting, and erythema. Pruritus is a hallmark manifestation of AD that can cause frequent scratching, leading to skin infections and lichenification.¹ The face, scalp and extensor surfaces are commonly involved in infancy, while there is prominent flexural involvement in older children and adults.² While some patients experience resolution by adolescence, others have symptoms that persist into adulthood.³ AD has been estimated to affect 15-30% of children and 10% of adults in industrialized nations.⁴ The economic burden of AD has been estimated to be $3.8 billion per year.⁵ Due to the chronic nature of AD and limitations of current available topical agents, especially for pediatric use, there remains an unmet need for novel AD therapies to address long-standing treatment gaps. Crisaborole 2% ointment (Eucrisa™) is a Health Canada and US FDA-approved topical phosphodiesterase-4 (PDE4) inhibitor for treating mild-to-moderate AD. Evidence from phase 3 and 4 trials demonstrate crisaborole is an effective agent with a well-tolerated side effect profile for children >2 years of age.⁶

Overview: Diagnosis and Pathogenesis

The diagnosis of AD is clinical. Skin biopsy and laboratory testing such as serum immunoglobulin E (IgE) levels are not routinely performed in the evaluation of suspected AD, but may be useful in ruling out other skin conditions.⁷ Adverse impacts from AD are wide ranging and include impairments to general health, quality of life, and mental health, with the financial cost of disease management posing a significant concern for patients and their families. Scratching may expose patients to secondary infections, which can exacerbate the severity of AD.⁸ The differential diagnosis for AD includes irritant or allergic contact dermatitis, serborrheic dermatitis, psoriasis, and scabies. Intractable, chronic itch is a hallmark of AD. Scratching may expose patients to secondary infections, which can exacerbate the disease severity.⁶

The pathogenesis of AD is determined by numerous factors including abnormalities in the skin barrier, a skewed T helper type 2 (Th2) immune response, impaired innate immunity, and changes in the resident microbial flora of the skin.⁹ The epidermis of patients with AD is prone to increased transepidermal water loss.¹⁰ The filaggrin (FLG) protein, which is produced by keratinocytes and encoded by the FLG gene, serves a critical role in skin barrier formation.¹¹ Patients with AD have lower levels of expression of skin barrier-related proteins including FLG-2, corneodesmosin, and enzymes necessary for skin hydration and water retention at the stratum corneum.¹² In addition to a barrier defect, the underlying immune system is also dysregulated in patients with AD. The innate immune response depends on toll-like receptors, which are stimulated by tissue damage and microorganisms, and enhance the strength of tight junctions to prevent allergen and microorganism penetration.¹³ Grouping patients with AD into one endotype may be overly simplistic. AD has a variety of endotypes depending on age groups, ethnicities, FLG mutations, and IgE levels.¹⁴ These include Asian versus European American, adults versus children, and presence or absence of family history of FLG mutations.¹⁴ Since increased Th2 cell levels are common across the spectrum of AD, targeting this factor should theoretically be therapeutic for all phenotypes of AD. However, phase 3 trials of dupilumab, an interleukin (IL)-4 and IL-13 blocker targeting the Th2-mediated pathway, was only able to reduce the Investigator’s Global Assessment score of patients down to 1 or 0 in 36-38% of cases.¹⁵ This suggests that other immune mediators outside of Th2 cells may be involved in the pathogenesis and treatment of AD.

Treatment Options for Atopic Dermatitis

The goals of treatment for AD are to achieve symptom reduction and prevent exacerbations. This approach is balanced with minimizing the risks of therapy. The mainstay therapy of AD is topical corticosteroids (TCS).¹⁶ An alternative to TCS is topical calcineurin inhibitors (TCI). Both treatments elicit potential side effects if used improperly. The face and skin folds are areas at high risk for atrophy with inappropriate use of TCS. High potency TCS also pose the risk of systemic toxicity, such as adrenal suppression in pediatric populations, especially if used under occlusion, e.g., diapered area.^17,18 TCI medications such as topical tacrolimus ointment and pimecrolimus cream do not carry the risk of skin atrophy, but may burn and sting on application. Patient education is needed as topical tacrolimus and pimecrolimus come with an FDA black box warning for increased risk of malignancies such as lymphoma.^19,20 Since the regulatory manadate to include the black box warning was institued in 2005, there has been mounting evidence to support the safe use of TCIs and the increased risk of malignancy remains theoretical. Prior to topical crisaborole, no new topical molecules have been approved to treat AD over the last 15 years.

Severe AD may warrant the use of ultraviolet-B (UVB) phototherapy or systemic immunosuppressant therapy such as cyclosporine, methotrexate, or mycophenolate mofetil when the patient is refractory to topical treatments.²¹ In 2019, both the FDA and Health Canada approved dupilumab for treating patients with AD >12 years of age who suffer from moderate-to-severe AD when topical therapies are ineffective or not advised.^22-24 Dupilumab is a fully human monoclonal antibody that binds to the IL-4 receptor and inhibits signaling of IL-4 and IL-13.²⁵

Crisaborole 2% is a topical PDE4 inhibitor indicated for the treatment of mild-to-moderate AD. Studies have shown that crisaborole 2% ointment improves AD signs such as exudation, excoriation, lichenification, and especially pruritus. Unlike TCS and TCI therapies, systemic exposure to crisaborole is limited.²⁶ The most common side effects are pain and paresthesia at the application site.²⁷

Crisaborole‘s Mechanism of Action

Crisaborole inhibits the action of PDE4. Pharmaceutical interest in phosphodiesterase enzymes, including crisaborole, was sparked by their role in nucleotide signaling pathways, leading to the development of specific novel inhibitors.²⁸ Elevated PDE4 enzyme levels have been associated with a chronic inflammatory state.²⁹ Since PDE4 is expressed by immune cells and keratinocytes, inhibition of PDE4 increases intracellular levels of cyclic adenosine monophosphate (cAMP) which inhibits the nuclear factor kappa B (NF-kB) pathway and the release of tumor necrosis factor (TNF)-alpha and pro-inflammatory cytokines that have a causal role in AD and psoriasis.²⁹

Crisaborole’s boron chemistry allows for formation of a low molecular weight molecule that penetrates human skin effectively.³⁰ Systemic exposure and risk of adverse effects from crisaborole is generally avoided due to the molecule’s rapid metabolism to inactive metabolites that do not affect cytokine release or the activity of PDE4.²⁹

Completed and Ongoing Studies of Crisaborole

Crisaborole’s safety profile and efficacy has been evaluated through 2 double-blind vehicle-controlled controlled phase 3 clinical trials. These studies assigned patients aged 2 years and older with mild or moderate AD as per Investigator’s Static Global Assessment (ISGA) scoring for treatment with either 2% crisaborole ointment or vehicle for 28 days. Results collected on day 29 demonstrated that 51.7% of patients receiving crisaborole had an ISGA of clear (0) compared to 40.6% of vehicle-treated patients (P = 0.05) and 48.5% of patients had ISGA of almost clear (1) compared to 29.7% of those treated with vehicle (P < 0.001).⁷

Two randomized, double-blind, vehicle controlled phase 3 studies with 759 and 763 participants demonstrated that crisaborole improves pruritus compared with vehicle (56.6% vs. 39.5%; P < 0.001) as early as day 2 of therapy (34.3% vs. 27.3%; P = 0.013).³¹

TCS are routinely used as therapy for flare-ups in AD.³² However, only short-term TCS use is recommended to minimize local and systemic adverse effects such as striae, telangiectasia, cutaneous atrophy, and acne.³³ As for TCI, both Health Canada and FDA initially advised against the use of long-term TCI therapy due to the unclear risk of malignancy.^19,20 Health Canada has subsequently removed the black box label for primecrolimus.³⁴ However, patients may continue to be apprehensive about using TCIs given their previous black box labeling. More research, including investigations on long-term maintenance, is needed to determine optimal topical treatment options for AD with favorable safety profiles. There is a phase 3 randomized, double-blind, vehicle-controlled study being conducted with 700 patients with mild-to-moderate AD.³⁵ Patients will receive crisaborole twice a day for a maximum of 8 weeks to identify responders, defined as ISGA score of 0 or 1 with 2-grade improvement from baseline or 50% improvement from baseline based on Eczema Area and Severity Index (EASI50) scoring. Non-responders will be discontinued after the 8-week run-in period. Maintenance treatment consists of once daily administration of crisaborole QD. Flares defined as ISGA ≥2 will be treated with twice daily crisaborole for up to 12 weeks. Completion of the trial is anticipated by July 2022.³⁵

The efficacy and safety profile of crisaborole is currently being investigated in phase 4 trials. A randomized, double-blind, vehicle-controlled study is evaluating the efficacy and safety of 3 different application rates of crisaborole ointment 2% in adults with mild-to-moderate AD.³⁶ Each patient will have 4 application areas and receive 1 of 4 treatments ranging from vehicle to 3 different application rates of crisaborole. Patients will be randomly assigned to treatment with topical crisaborole (application rates A, B, or C) or vehicle, once daily, for 2 weeks. The results of this study, with a projected completion of June 2020, may demonstrate whether the efficacy and safety of crisaborole is dose dependent. The results may be compared and contrasted with TCS use, which has a well-known dose dependent effect (e.g., anti-inflammatory effects at lower doses, immunosuppressive activity at higher doses) as well as dose dependent adverse effects (e.g., ecchymosis, parchment-like skin, and sleep disturbances).³⁶

Long-term topical treatment is often required for the management of a chronic inflammatory skin conditions like AD. Crisaborole’s long-term safety was evaluated in an open-label extension study of 517 patients with mild-to-moderate AD who used crisaborole for 48 additional weeks after the 28-day phase 3 study. The most frequently reported treatment related adverse effect (AE) were AD (3.1%), pain at the site of application (2.3%), and localized infection (1.2%).²⁷

The treatment options for patients under 2 years of age with AD are sparse. Pimecrolimus has recently been approved for infants as young as 3 months.³⁷ However, having a wider array of therapeutic strategies would be ideal for this demographic. A phase 4 multicenter, open-label, single arm investigation called the CrisADe CARE 1 study evaluated the safety, efficacy, and pharmacokinetics of crisaborole 2% ointment applied twice daily on 125 pediatric patients between 3-24 months of age.³⁸ These patients had extensive AD involving at least 5% of body surface area (BSA) except for the scalp. A total of 29.93% of patients reported non-serious AEs. The most common side effect was pyrexia (9.49%). The study found a total of 1 (0.73%) serious AE involving a febrile convulsion. The study did not comment on whether this AE was related to the use of crisaborole. No deaths occurred. This study is the first to evaluate the safety profile of crisaborole in children less than 24 months of age.

Crisaborole may have the potential of decreasing steroid use in patients with AD. Side effects of TCS can range from cutaneous atrophy to suppression of the hypothalamic-pituitary-axis.³⁹ Misunderstandings and steroid phobia can interfere with patient compliance, which in turn negatively affect disease control.⁴⁰ Currently, a proof-of-concept phase 4 clinical trial with 60 children between 2-18 years with mild-moderate AD is underway to determine whether crisaborole is an effective steroid reducing agent. The trial will be completed by November 2020.⁴¹ Similarly, a single-center observational prospective cohort study aimed to evaluate the efficacy and safety profile of crisaborole ointment 2% and a TCI versus crisaborole alone over 8 weeks. The study included participants aged 2-79 with mild-tomoderate AD and the projected completion was March 2020.⁴²

While high-quality phase 3 studies have demonstrated the efficacy of crisaborole compared to vehicle, head-to-head studies comparing crisaborole with TCS or TCI are needed to better define its role in the management of AD. A phase 4 multicenter, randomized, vehicle versus active (TCS and TCI) controlled study is being conducted on 600 patients with mild-to-moderate AD over 4 weeks to evaluate the safety and efficacy of crisaborole 2% ointment, crisaborole vehicle, TCS, and TCI applied BID in patients over 2 years of age.⁴³ Inclusion criteria include patients with AD involving at least 5% of BSA except for the scalp. The primary efficacy endpoint is change from the patient’s baseline in the EASI score by Day 29. The study will be completed by March 2021. This will be the first study to directly compare crisaborole to the current mainstay treatments of mild-to-moderate AD.

Conclusion

Crisaborole provides a novel and safe treatment option for mild-to-moderate AD. Crisaborole’s boron chemistry allows for formation of a low molecular weight molecule that penetrates human skin effectively but is inactivated and metabolized rapidly.³⁰ Crisaborole therapy has been shown to decrease pruritus, which disrupts the itch-scratch cycle that exacerbates signs of AD, improve quality of life, and decrease the risk of infection and scarring.⁴⁴ Adverse events related to crisaborole 2% are overall infrequent and range from mild-to-moderate in severity. Studies are currently underway to determine whether crisaborole can be used as long-term maintenance therapy for patients who respond to treatment. Furthermore, while crisaborole’s side effect profile is generally well tolerated, new head-to-head studies comparing crisaborole with TCS or TCI are underway to better define its role in the management of AD.

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¹Associate Professor, Department of Medicine, University of Toronto, Toronto, ON, Canada
²Clinical Assistant Professor, Department of Dermatology, University of British Columbia, Vancouver, BC, Canada
³Clinical Professor, Director of Pediatric Dermatology, University of Alberta, Edmonton, AB, Canada
⁴Professor, Western University, London, ON, Canada
⁵Assistant Professor, Department of Medicine, Department of Pediatrics, University of Toronto, Toronto, ON, Canada
⁶Assistant Professor, Department of Pediatrics and Child Health, University of Manitoba, Winnipeg, MB, Canada
⁷Division of Dermatology, Sainte-Justine University Medical Center; Clinical Professor in Pediatrics, University of Montreal, Montreal, QC, Canada
⁸Division of Dermatology, Sainte-Justine University Medical Center; Clinical Professor in Pediatrics, University of Montreal, Montreal, QC, Canada
⁹Clinical Associate Professor, Department of Pediatrics, University of Calgary, Calgary, AB, Canada

Funding:
This Supplement was developed using the Authors’ Expert Opinion, supported by an unrestricted Educational Grant from Pfizer Canada.
Use crisaborole ointment in off-label settings is left up to the discretion of the treating health care professional after careful clinical evaluation.

Abstract:
Background: Atopic dermatitis (AD) is associated with epidermal barrier dysfunction. The chronic skin condition presents clinically with pruritus and recurrent skin lesions. The psychosocial impact of the condition is severe for most patients and their families.
Crisaborole, a topical PDE4 inhibitor, has demonstrated efficacy in patients with mild-to-moderate AD.

Objectives: A diversity of cases are presented that reflect real-world clinical use of topical crisaborole ointment, as a mechanism to help optimize patient care.

Methods: Evidence from the literature coupled with the panels’ expert opinion, experiences and, key insights reflect the panels’ clinical use of topical crisaborole ointment for AD and irritant dermatitis (off-label use) and how patients can benefit from its use, i.e., “what experienced specialists are doing across Canada.”

Results: The panel treated and presented cases that report on crisaborole ointment used as monotherapy, combination therapy, sequential therapy, and maintenance therapy. The presented cases aim to illustrate the diversity of crisaborole use concerning age range, skin type/ethnicity, and body location. Each case presents a summary of the learning points.

Conclusions: The presented cases reflect the panels’ real-world clinical experience with crisaborole for the treated patients. The panel suggested that crisaborole ointment provides a good safe alternative to TCS and TCI. Treatment with the ointment should be avoided on severely flaring skin and for those that experience irritation, burning, or stinging while testing it on unaffected skin areas.

Key Words:
Atopic dermatitis, Real-world cases, Topical PDE-4 inhibitor

Introduction

Atopic dermatitis (AD) is a lifelong inflammatory skin condition associated with epidermal barrier dysfunction and altered immune function, presents clinically with recurrent episodes of pruritic erythematous papules and plaques.¹ AD usually starts in infancy, where it affects up to 20% of children in North America, and is also highly prevalent in adults.² Two-thirds of AD patients are reported to have mild disease, 26% moderate, and 7% severe AD disease.³ The majority of patients are treated by primary care physicians who primarily use topical anti-inflammatory therapy for their mild-to-moderate AD cases.^4-13

The psychosocial burden of AD on patients and their families is enormous.¹⁵ The inflammatory skin disease increases the risk of other immune-mediated inflammatory atopic disorders, such as asthma, allergic rhinitis and food allergies, as well as mental health disorders in some.^15,16

Patients with AD should use gentle cleansers and moisturizers that are balanced to the skin pH in addition to behavioural measures such as avoidance of irritants and triggers.

AD is a chronic relapsing disorder with periods of quiescence punctuated by intermittent flares. When AD flares then treatments such as topical corticosteroids (TCS), topical calcineurin inhibitors (TCI), and more recently, phosphodiesterase-4 (PDE4) inhibitors should be considered, while continuing skincare and measures to avoiding triggers of AD. TCS and TCI treatments are widely used as monotherapy in cases of mild-to-moderate AD or in combination with systemic treatments for more severe AD involvement. These treatment regimens are supported by clinical guidelines and clinical pathways worldwide and have an established safety record.^4-13 Crisaborole ointment (Eucrisa, Pfizer), a unique topical prescription option for AD, is a PDE4 inhibitor with demonstrated efficacy in patients aged two and older with mild to moderate AD.¹⁶

The presented real-world case-based approach explores the role topical crisaborole can play in the prevention, treatment and maintenance of AD and other inflammatory skin conditions, in clinical practice. The selected patient cases aim to outline a diversity of cases that reflect real-world use of topical crisaborole ointment for patients with AD and other skin conditions, either as monotherapy or in combination with other treatments. Any discussion concerning off-label use is considered an expert opinion only.

Methods

Aim of the Project

This current real-world case project was conceived as a mechanism to help optimize patient care by recognizing the role crisaborole ointment can play in the prevention, treatment and maintenance of AD. Additionally, the project explores where this therapeutic agent could be used in managing AD in patients who require a combination of therapies. The cases intend to illustrate the authors’ real-world clinical experience rather than reflect controlled clinical trial data. Evidence coupled with the expert opinion, experiences, key insights and recommendations is presented and discussed. Recommendations given by the panel reflect the use of topical crisaborole ointment for AD and how patients can potentially benefit from its use, i.e. “what experienced specialists are doing across Canada”. Any discussion concerning off-label use is considered an expert opinion only.

The target audience for this publication is physicians and other health-care professionals who treat patients with AD.

Steps in the Process

The five-step procedure included a) project definition and panel selection, b) collection of information and preparation of cases, c) meeting to select cases for the publication, d) literature review to support the cases, and e) creation, review, and finalization of the manuscript.¹⁷

Role of the Panel

An expert panel of eight dermatologists and pediatric dermatologists, selected to represent the diverse geographical regions within Canada, who commonly treat patients with AD, was convened on November 9, 2019, in Toronto, as part of the semiannual Dermatology Update conference. The panel members reported clinical cases of pediatric and adult patients who were suitable candidates for crisaborole ointment treatment.

The panel members discussed the cases in the light of the supporting literature, then decided which cases would be included in the publication. The publication was prepared and reviewed by the panel members.

Topical Treatment for Mild-To-Moderate AD

Avoidance of triggers of AD flares and education are the first steps in the prevention, treatment, and maintenance of AD.6

Skincare Using Gentle Cleansers and Moisturizers

Skincare using gentle cleansers and moisturizers remains the cornerstone of treatment for all severities of AD. Daily use of this skincare regimen is supported by established guidelines and clinical pathways.^4-13 Moisturizers play an important role in combating and controlling xerosis, decreasing epidermal water loss, and restoring epidermal barrier function.^6,10 Moisturizers should be liberally and frequently applied and can be used alone for mild disease or in combination with other therapies regardless of the severity of their AD. ^6,10

TCS and TCI

If avoidance of triggers and the use of a daily skincare regimen with gentle cleansers and moisturizers are not effective, topical anti-inflammatory agents, such as corticosteroids (TCSs) or calcineurin inhibitors (TCIs) are used twice a day until the lesions have cleared.^3-13 TCS is the first-line anti-inflammatory option, available in a variety of strengths from mild to potent and very potent.^6,11 Side effects such as skin atrophy, purpura, telangiectasia, striae, focal hypertrichosis, impaired wound healing, allergic contact dermatitis, and acneiform or rosacea-like eruptions on the face are very uncommon when TCS is used appropriately.⁶ Both patients’ and parents’ fear of TCS and steroid phobia should be discussed to improve adherence and avoid under-treatment.⁶

TCI’s are another safe and effective treatment option, however short-term side effects such as skin burning, and pruritus, especially when applied to acutely inflamed skin and cutaneous viral infections, may occur.⁶ Patients and parents should be informed about these potential side effects to avoid premature discontinuation of treatment.⁶ TCIs are therapeutic agents often used for mild AD on the face, neck, and folds, and used in prevention and TCS reduction elsewhere on the body.

Systemic Therapy

For patients affected by more severe AD, agents that target immune responses and inhibit T cells by targeting Th1, Th2, Th22, phosphodiesterase-4 (PDE4), IL-4, and IL-31 are available.¹⁸ Phototherapy and traditional systemic therapies, including methotrexate, cyclosporine, and mycophenolate mofetil, can also be used off-label in severe AD.

Crisaborole Ointment

Crisaborole (Eucrisa, Pfizer), a topical prescription option for AD, is a PDE4 inhibitor with demonstrated efficacy in patients aged two and older with mild to moderate AD.16 Two, multicenter phase III trials, demonstrated early sustained control of mild-to-moderate AD in patients aged over two years with crisaborole ointment use over twenty-eight days.¹⁶ When compared to the vehicle, treatment with the 2% crisaborole ointment showed reduced pruritus, AD severity, and other signs of AD (erythema, exudation, excoriation, induration/papulation, and lichenification), although clinicians have expressed concerns about stinging and burning on at application sites.^16,19

A multicenter extension study indicated that crisaborole ointment for up to fifty-two weeks is safe.¹⁷ The extension study reported an overall 10.2% rate of crisaborole treatment-related adverse events such as dermatitis (3.1%), application site pain, stinging, burning (2.3%), and application site infection (1.2%).³ These events were considered mild, and no one withdrew from the study due to these adverse events.

Less common potential side effects included skin irritation and hives or welts, which may be due to underlying atopy. Given the good tolerability and safety profile, crisaborole ointment makes for an alternative steroid-sparing topical option to TCS and TCI.¹⁶

Data Gathering of Real-World Cases on Crisaborole Ointment Use

The panel members used a template for their case studies, which asked the following questions:

• What are the cases and the impact of the condition?
• What are the treatment options, and what treatment(s) were previously used for this case
• Why might crisaborole ointment work in this case, where does it fit and what were the results of the treatment?
• Did any adverse events occur? If yes, describe.
• What (if any) are the special circumstances related to this particular case, and which lessons are learned?

Patient evaluations were at baseline (start) and at eight weeks (+/- 5 days) using physician reported skin condition (SCORing Atopic Dermatitis Clinical assessment [SCORAD] score.²¹ SCORAD recorded AD location and percentage area (A), Intensity (B): Redness, swelling, oozing/crusting, scratch marks, skin thickening, dryness [the intensity of each of the following signs is scored as none (0), mild (1), moderate (2) or severe (3)] and subjective symptoms (C) [Sleeplessness: 0 = no sleeplessness and 10 = the worst imaginable sleeplessness, Itch: 0 = no itch and 10 = the worst imaginable itch]). Total SCORAD is the sum of A, B, and C, minimum score = 0, maximum score = 103.21 The impact of the skin condition after treatment regime use and adverse events were recorded at baseline (start) and week 8 (+/- 5 days) (end).

Some of the physicians used quality of life for the participants 15 years or younger as assessed by Children’s Dermatology Life Quality Index (CDLQI). The minimum score is 0, and the maximum score is 30, the latter corresponds with the most severe impairment of quality of life. Other scores used were severity of itching as assessed by the Pruritus score determined using the Numerical Rating Scale (Minimum score is 0. The maximum score is 10, the latter corresponding to the most severe itching imaginable by the patient).

Selected Real-World Cases

The panel selected a total of eleven cases that reported on realworld use of crisaborole ointment as monotherapy, combination therapy, sequential therapy, maintenance therapy, preventive therapy, and its application in dermatitis beyond AD. (Table 1). The presented cases aim to illustrate the diversity of crisaborole use concerning age range, skin type/ethnicity, body location, the severity of AD, and reports of off-label use.

Case 1: A 4½-year old girl with AD since the first months of life, which had recently increased in severity. The moderate-tosevere condition involved multiple sites, including hands and feet. Previous treatment with various TCS formulations was unsuccessful. When crisaborole started, mometasone ointment was continued as needed on the lesions on her body. The rationale for starting topical 2% crisaborole ointment was the failure of previous treatments and a specific interest in improving the skin condition of her hands and feet. Her skin condition markedly improved over the eight week treatment period (Figure 1A-1J). No adverse events occurred, and the ointment was well tolerated even on the face.

Learning point: Crisaborole is a well-tolerated (even on the face) alternative for TCS and is effective on hands and feet.

Figure 1A – 1D

Figure 1E and 1F

Figure 1G and 1H

Figure 1I and 1G

Case 2: For four months, a 4-year-old boy had suffered from AD, primarily on the face, antecubital, and popliteal fossa. He had almost constant pruritus and open, erythematous skin. His interaction with other children was poor, and both the patient and parents had difficulty sleeping. Previous long-term TCS treatments lacked success. Moreover, his mother was concerned about prolonged steroid use and requested trying crisaborole ointment. After eight weeks of crisaborole ointment application, his skin condition had greatly improved (Figure 2A and 2B). Although at first, the ointment caused skin irritation, this was easily alleviated with the use of a moisturizer.

Learning point: Crisaborole seems to induce irritation, burning, and stinging more frequently in clinical practice than reported in clinical trials. The patient experienced irritation, burning, and stinging in the areas where crisaborole was used. Information and education on measures to prevent or to treat these side-effects were effective. The advice given included the use of a refrigerated moisturizer, frequently applied before and after application of the ointment to optimize crisaborole results and decrease irritation. The mother was encouraged to continue treatment after the physician discussed the expected outcomes of the therapy. The irritation was alleviated with the use of a moisturizer as instructed.

Figure 2A and 2B

Case 3: A 29-year-old neonatal intensive care unit (NICU) nurse developed hand dermatitis one year ago. During work, she frequently used a hand sanitizer causing pruritus and painful fissures. She had a negative history for AD, and other atopic disorders and Patch tests were negative. The eruptions cleared when she was on holiday. After consultation with the occupational health department for help and guidance, she received a special hand sanitizer. She refused TCS as she was concerned about developing skin thinning. Within eight weeks of starting crisaborole ointment, the condition had resolved. The ointment was well tolerated, and she resumed her work as a NICU nurse (Figure 3A and 3B).

Learning point: The patient with occupational irritant hand dermatitis did not want to use TCS. The alternative treatment with crisaborole ointment was successful for this patient. Use of crisaborole in the treatment of irritant contact hand dermatitis is off-label.

Figure 3A and 3B

Case 4: A 68-year-old woman with a history of rosacea also had recurrent facial eruptions. Patch testing was positive to Kathon CG, which was found in her laundry product which she had since avoided. Since TCS were unsuccessful, treatment with crisaborole ointment was started, used in combination with ceramides containing cream as needed. Her skin condition markedly improved within two weeks (Figure 4A – 4D).

Learning point: The ointment may be a useful alternative for TCS for facial areas in patients with concomitant facial inflammatory skin conditions. Although crisaborole may induce irritation, burning, and stinging, in this patient with underlying rosacea, the product was well tolerated. Topical steroids can induce a rosacealike eruption. Crisaborole did not aggravate this patient’s rosacea. Patch testing was useful in identifying the causative allergen. The use of crisaborole in allergic contact dermatitis is off-label.

Figure 4A and 4D

Case 5: An 11-month-old baby-boy had facial AD from the age of nine months. He had coincident acute myelogenous leukemia (AML) and was recovering from chemotherapy. His parents were concerned about TCS and TCI being immunosuppressive agents and due to his ongoing AML treatment refused them. Crisaborole ointment seemed a good alternative option. His skin condition improved within an eight week observation period, and no adverse events occurred (Figure 5A – 5D).

Learning point: In immunosuppressed or otherwise vulnerable patients, crisaborole ointment is an effective alternative to TCS to treat AD even on the face. Parental wishes to not use TCS or TCI were granted because crisaborole’s mechanism is not immunosuppressive. Although crisaborole is approved for use in individuals 2 years of age and older, it was safely and effectively used in this infant.

Figure 5A and 5D

Case 6: A 2-month-old baby boy presented with diffuse xerosis and AD present since three days of age. His condition impacted the entire family. His mother had applied Vaseline six times a day and TCS twice a day. He had not responded to treatment with several different types of TCS. The physician was concerned about absorption and possible adrenal axis suppression. After eight weeks of crisaborole ointment use, pruritus had subsided and both the baby and his family were able to sleep through the night (Figure 6A and 6B). Before starting treatment with crisaborole ointment, he had regularly had skin infections with MRSA, which did not reoccur since the start of the crisaborole ointment.

Learning point: Crisaborole proved to be a useful alternative for TCS where absorption and possible adrenal axis suppression were a major concern. Of interest is the resolved recurrent infection since the use of crisaborole, which may be attributed to the improved skin condition. Crisaborole is approved for use in individuals with AD two years of age and older.

Figure 6A and 6B

Case 7: A 15-year-old male had recurrent resistant atopic dermatitis and dyspigmentation from chronic TCS use. Treatment of the generalized flares and superinfection consisted of intravenous antibiotics and oral cyclosporine, to which he had a good initial response. To address his concern about TCS use and the desire for a simpler regimen, twice daily application with crisaborole ointment was started while continuing the cyclosporine. After eight weeks of use, he had an excellent response, with marked improvement in his quality of life. Whenever the patient stops topical crisaborole, some AD returns (Figure 7A and 7B).

Learning point: The use of crisaborole ointment in combination with systemic therapy was effective for this patient. The ointment is to be applied at the first sign of a flare before lesions develop and avoided the need to increase systemic therapy. As a result, he gained confidence in controlling his skin condition and improving his outlook on his situation.

Figure 7A and 7B

Case 8: A 5½-year-old boy had mild-to-moderate AD since the age of three and recently developed symptomatic hand and feet involvement. The rationale for crisaborole use on his hands and feet was the suboptimal response to previous TCS/TCI therapy. Concomitant use of TCS and TCI was continued together with crisaborole. His skin had almost cleared after eight weeks of crisaborole ointment use (Figure 8A – 8D).

Learning point: An incremental benefit of adding crisaborole as part of a combination regimen with TCS and TCI TCI introduces new possibilities for patients with AD on their hands and feet.

Figure 8A and 8D

Case 9: Since the first months of life, a 5-year-old male has had moderate-to-severe AD with symptomatic painful involvement of his hands, impacting daily activities. He had difficulty handling toys and interacting with other children and their parents. TCS and TCI treatments were not successful. With crisaborale, his hand palms and wrists’ involvement almost completely cleared. (Figure 9A – 9E).

Learning point: Effective penetration of crisaborole on thicker skin such as hand-palms and foot-soles may facilitate improvement in these special sites.

Figure 9A and 9B

Figure 9C and 9E

Case 10: A 4-year-old girl had AD. TCS therapy was started for her flaring disease. Her mother was concerned about vaccines and TCS use. Crisaborole ointment treatment was started to address the mother’s concerns. At eight weeks of ointment application, there was an 80% clinical improvement; however, some moderate AD persisted at some sites which required strong TCS.

Learning point: Although the crisaborole ointment did not completely resolve the disease, the mother preferred it to TCS for milder lesions and wished to reserve TCS for more resistant lesions.

Figure 10A and 10G

Case 11: A 12-year-old male with AD since infancy had involvement of the hands and limbs. His condition failed to show improvement from intermittent TCS. The rationale for starting crisaborole ointment was the family’s frustration with the lack of results and a possible penetration advantage of the ointment on the hands. A left/right assessment of clobetasol versus crisaborole ointment was conducted. His mothers’ perceptions were that his hands both improved, but the crisaborole ointment was more effective than clobetasol. On the arms and legs, both treatments were successful, but clobetasol outperformed crisaborole ointment. The therapy was continued after the eight weeks study period as the family was happy with the treatment response. No adverse events occurred. Subsequently, mom used crisaborole alone on his hands and had ongoing good maintenance and prevention of flares. (Figure 10A – 10G). Follow up results are shown in Figure 11A – 11E.

Learning point: The crisaborole ointment performed better on the hands than clobetasol, however when used on the arms and legs, the reverse was the case, indicating that the ointment may be particularly useful on thicker skin areas.

Figure 11A and 11E

Discussion

For each case, the age, skin type, underlying skin condition, rationale for using crisaborole, and in some cases, treatment duration were highlighted as well as its role as part of a maintenance/prevention and treatment regimen. The cases presented a spectrum of clinical responses to crisaborole, including instances of poor response, such as in case 10, where AD persisted, and TCS was further needed. The panel discussed challenges of recognizing and managing AD in darker skin which may be addressed using crisaborole ointment, although studies are needed to confirm possible benefits. Most of the cases were atopic dermatitis, the approved indication. Two other types of dermatitis (hand dermatitis, allergic contact dermatitis) were included although they have not approved indications since these conditions are often difficult to treat and do not always respond to topical steroids. In addition, on the face, topical steroids may be associated with a greater potential for adverse events.

Steroid Phobia

Steroid phobia refers to the negative feelings and beliefs related to TCSs experienced by patients and patients’ caregivers. The panel expressed concerns that this phenomenon may be a contributing factor in treatment failure in AD patients. A systematic review²² found that TCS phobia is present across all cultures and that adequate information for patients and parents is lacking. The authors of the systematic review propose that the sources from which patients are receiving information about TCS may be targetable for intervention to increase adherence to TCS treatment regimens.²²

Crisaborole can be an effective alternative for TCS and TCI, especially in patients with conditions requiring long-term TCS or TCI use.

In case of safety concerns (even when subjective) with TCS and TCI use in young patients or concerns about steroid absorption in all groups, patients can safely use crisaborole ointment. Moreover, preservatives in crisaborole pose no safety issues. The panel agreed that crisaborole ointment provides a good safe alternative to TCS and TCI in such cases, enhancing treatment adherence and thus outcomes.

Irritation, Burning and Stinging

Crisaborole seems to induce irritation, burning, and stinging more frequently in clinical practice than reported in clinical trials.^3,6,19 This side effect was also reported for two of the presented cases (case 2 and 4). The panel suggested that in their experience, irritation, burning, and stinging are more quickly resolved than in the case of TCI use, where similar side effects are also observed. If TCI related stinging occurs most clinicians will apply steroids temporarily and then subsequently TCIs are usually tolerated.

The panel recommended providing information on this issue and education on measures to prevent or to treat it before the start of the treatment with crisaborole. The panel recommended frequent use of a refrigerated moisturizer before and after application of the ointment, and the use of an anti-itch lotion as needed throughout the day. The panel further suggested that it may be helpful to have patients testing crisaborole on healthy skin. Modify or discontinue the treatment if the formulation triggers burning or stinging even on healthy skin with concomitant use of a refrigerated moisturizer. The panel discussed avoiding crisaborole ointment use on severely flaring skin and starting with TCS until the flare is controlled, followed by crisaborole ointment.

Antibiotic Resistance

Antibiotics are commonly used as part of the management of AD. However, only a minority of patients with AD have clinically significant S. aureus infection. Moreover, data is lacking for highly beneficial outcomes with exclusive use of antibiotics in the management of AD.²³ Case 6 shows an example of the possible use of crisaborole as a steroid-sparing and antibiotic-sparing agent. Because of antibiotic resistance, the use of the crisaborole ointment may be of interest and aligns with current emphasis on antibiotic stewardship in AD. Anti-inflammatory agents control eczema, which leads to less frequent infections and less antibiotic use.

Combination Treatment

Combining or alternating crisaborole with TCS or TCI may be successful for more severe disease. The ointment was safely used in time-intervals between the application of a moisturizer, TCS, or in combination with systemic therapy. Several cases showed a marked improvement in the skin condition of the treated patients and no adverse events.

Specific Body Locations

Case 4 shows an example of the safety and tolerability of crisaborole when used on specific sites (e.g., face and lips). An incremental benefit of crisaborole use as part of a combination regimen was shown in a patient (case 8) who recently had AD involvement of his feet, with hyperkeratosis and desquamation.

The rationale for crisaborole use, in this case, was good absorption of the ointment due to the relatively small size of the molecule allowing better penetration.

Case 11 showed beneficial crisaborole use on the hands, which did not improve with intermittent TCS application. This patient conducted a real-time comparative test using clobetasol on one side of the body and crisaborole on the other. Crisaborole worked better on the hands while clobetasol showed better results on his arms and legs.

The use of crisaborole for non-AD (case 3) was shown in a patient with occupational HD, which resulted in complete response. Advisors recommended further studies of crisaborole on the hands and feet (e.g., the study of occupational hand dermatitis and penetration study) to support the use of the ointment for these complex areas.

Table 1: Summary of the eleven cases studies
Case 1: TCS^a: Betametasone dipropionate 0.1% ointment, Mometasone ointment, TCI^b. Tacrolimus 0.1% ointment, Skincarec: Hydratation-Eucerin, Aquaphor, Aderma cleanser and hydrating agent.
Case 2: TCS^d: Desonide cream BID x 1 year, Hydrocortisone 17 valerate UNG BID x 1 year.
Case 3: TCS^e: Hydrocortisone cream
Case 4: TCS^f: 1% hydrocortisone cream
Case 6: TCS^g: Hydrocortisone 2.5%g then switched to desonide for body, Dermasmoothe FS for scalp and face. Then switched to hydroval 0.2% ointment to entire body.
Case 8: TCS^h: 0.1% betametasone valerate ointment (body), 0.1% protopic ointment (face).
Case 9: TCSⁱ and TCI: Betametasone dipropionate 0.1% ointment, Mometasone ointment, Tacrolimus 0.1% ointment.
Case 10: TCS^j: Begin with strong corticosteroids, Desonide ointment for the face, Betamethasone valerate 0,1% ointment for the hands and feet.
Case 11 : TCS^k : Clobetasol.

Atopic dermatitis (AD), Twice daily (BID), Crisaborole ointment (CO), Adverse events (AEs), Neonatal intensive care unit (NICU), Hand Dermatitis (HD), Medical history (Hx), Acute Myelogenous Leukemia (AML), Intravenous (IV) Oral (PO).

Maintenance Therapy

The panel discussed the spectrum of clinical response of crisaborole used in adjunction to a moisturizer as maintenance therapy and suggested that crisaborole ointment should start at the first sign of a new flare before the development of lesions. TCS should be added if it is not successful. Currently, data on the use of crisaborole ointment for long term maintenance therapy is lacking; however, the panel suggested further studies of crisaborole as maintenance therapy.

Conclusion

The discussed cases reflect the panels’ real-world clinical experience with crisaborole for the treatment of patients with AD and the off-label treatment of irritant dermatitis. The panel suggested that crisaborole ointment provides a good safe alternative to TCS and TCI. Use of crisaborole should be avoided on severely flaring skin and for those that experience irritation while testing it on unaffected skin areas.

Acknowledgement

The authors acknowledge and thank Anneke Andriessen, PhD, for her invaluable assistance with preparing this manuscript.

Limitations

The cases are intended to illustrate the real-world experience rather than reflect a controlled clinical trial data environment, nor do they presented cases mirror statistical outcomes. Use crisaborole ointment in off-label settings is left up to the discretion of the treating health care professional after careful clinical evaluation.

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¹Lecturer, Department of Family and Community Medicine, St. Michael’s Hospital, Toronto, ON, Canada
²Assistant Professor, Division of Dermatology, University of Toronto, Toronto, ON, Canada
³Associate Professor, Division of Dermatology, University of Toronto, Toronto, ON, Canada

Introduction

Atopic dermatitis (AD) is a chronic and pruritic inflammatory disease that affects a wide age range of patients causing significant impact on their quality of life. There has been a recently updated consensus paper on the treatment of mild-to-moderate AD published by an expert panel of dermatologists and pediatricians.¹ The primary objective of this article is to review the prevalence, pathophysiology, clinical features, diagnosis and treatment options for atopic dermatitis. The secondary objective is to disseminate the updated treatment algorithm suggested by the authors of the consensus paper for the primary care providers.

Prevalence

• Atopic dermatitis affects both pediatric and adult populations.
• Up to 20% of children have been reported to suffer from AD.²
• AD is more common in patients with a history of atopy such as allergic rhinitis or asthma.
• The majority of patients with AD have a positive family history of atopy.³

Pathogenesis

• AD is associated with impaired skin barrier, increased inflammation and altered microbiome.⁴
• A mutation in the filaggrin (FLG) gene that affects the natural skin barrier function is the most important genetic association.⁵
• There has been further evidence to suggest that there is a complex mechanism involving the JAK-STAT pathway and other immune responses via TH₂ and TH₂₂.
• Finally, AD is also associated with overproduction of phosphodiesterase 4 (PDE4) and subsequent pro-inflammatory cytokines.⁶

Clinical Features

• Atopic dermatitis has an intermittent nature and variable distribution that may change with age.
• Common clinical features include dry skin, pruritus and hyperreactivity to environmental exposures.
• The characteristic lesions of atopic dermatitis are ill-defined, erythematous, scaly, vesicular, excoriated and/or oozing papules and plaques that may become lichenified and fissured.
• In infants, AD often affects head, neck and extensor surfaces.
• In older children and adults, the antecubital/popliteal fossae, wrists and ankles are most commonly affected.

Diagnosis

• Atopic dermatitis is a clinical diagnosis. In unusual cases, a punch biopsy may help rule out potential mimics. Patch testing may help diagnose allergic contact dermatitis.
• The differential diagnosis for AD includes:
  • Irritant contact dermatitis
  • Allergic contact dermatitis
  • Seborrheic dermatitis
  • Plaque psoriasis
  • Scabies
• The most widely accepted diagnostic criteria by Williams et al.⁷ include:
  • Evidence of itchy skin AND three or more of:
    • Involvement of creases
    • History of asthma or hay fever (or history of atopic disease in children under four years of age)
    • Visible dermatitis involving flexural surfaces (including cheeks or forehead and outer aspects of limbs in children under four years of age)
    • Personal or family history of asthma or hay fever
    • Generally dry skin in the past year
    •  Onset in a child under two years of age
  • Severity scales for atopic dermatitis are available but not widely used by clinicians

Co-Morbidities

• Psychiatric disorders
  • Depression⁸
  • Suicide⁹
  • Attention deficit hyperactive disorder¹⁰

• Obesity

Treatment

The new DERMA Atopic Dermatitis Algorithm was developed for management of AD (Figure 1).

Diagnosis/Distribution
Education/ Emollients
Red/Itchy
Medication/Maintenance
Assessment /Adherence

Education

• The mainstay of treatment is patient education.
• Counselling should include:
  • Consistent use of emollients
  • Luke-warm bathing (with non-soap cleansers)
  • Avoidance of irritants such as fragrance

Emollients

• Emollients control xerosis and improve the epidermal barrier, with some suggesting products with humectants, lipids and/or ceramides.¹¹
• Application of moisturizers should be done immediately after bathing.

Topical Anti-Inflammatories

• The majority of AD patients have mild-to-moderate disease and only require topical therapies.
• Topical therapies include anti-inflammatory agents such as topical corticosteroids (TCSs), topical calcineurin inhibitors (TCIs) or phosphodiesterase-4 (PDE4) inhibitors in various vehicles.
• Ointments are generally better tolerated for nonintact “raw” skin as they do not contain preservatives, tend not to sting and can be more potent.
• Creams are often more cosmetically appealing but can sting on nonintact skin.
• Gels, sprays, lotions and foams may be useful for hair-bearing sites.
• Providers should re-assess patients for adherence, severity, and diagnosis after four weeks of continuous topical anti-inflammatory use.

TCSs

• Corticosteroids remain effective first-line treatments.
• Long-term adverse effects in sensitive areas include:
  • Local cutaneous atrophy
  • Striae formation
  • Telangiectasia
  • Impaired wound healing
  • Acneiform eruptions
  • Allergic contact dermatitis

TCIs

• Pimecrolimus 1% and tacrolimus 0.03% or 0.1% are safe and approved for children over age two.
• Common side effects are burning or stinging sensation on applications that subside over time.
• There exists a black box warning for possible lymphoma risk. However, patients should be counselled that causal relationship for this is unclear.¹²

PDE4 Inhibitors

• Crisaborole 2% ointment (Eucrisa©) is a novel topical applied twice daily to reduce symptoms of mild-to-moderate atopic dermatitis approved for patients two years and older.¹³
• Crisaborole showed efficacy by day 8 in clinical trials compared to vehicle and itch improves in less than two days.¹⁴
• Since there is no risk of steroid-atrophy, PDE4 inhibitors may be applied on the face and other sensitive areas of the body. Similar to TCIs, crisaborole is an alternative for steroid-phobic patients and/or caregivers.
• The most common side effect is application site burning, which is temporary.

Further Options

For severe AD, treatment options beyond topical therapies may involve phototherapy and/or systemic therapies such as cyclosporine, methotrexate, azathioprine, mycophenolate mofetil, or dupilumab.

Practical Tips

What about oral antihistamines?
A recent systemic review showed a lack of consistent evidence for use of oral antihistamines (e.g. cetirizine, loratadine, fexofenadine) when compared to placebo in decreasing symptoms of atopic dermatitis.¹⁵

What about food allergens?
Although patients with AD often have food allergies to cow’s milk, egg, wheat and peanut, there is no evidence that dietary interventions provide any benefit in the treatment of AD.¹⁶

What about bath additives?
Although some guidelines in Europe support the use of bath additives, there is no consistent data to demonstrate its efficacy in controlling pruritus.¹⁷

What about allergy testing?
Patch testing is not required to diagnose atopic dermatitis. It is only necessary for excluding the alternative diagnosis of irritant contact dermatitis.¹⁸

Conclusion

There are several topical therapy options available for the management of AD such as TCIs and PDE4 inhibitor. Family physicians are well equipped to manage mild-to-moderate AD in the majority of cases, but referral to dermatologists may be required in severe cases or alternative diagnoses.

¹Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
²Division of Dermatology, University of Alberta, Edmonton, AB, Canada

Conflict of interest:
The authors have no conflicts to declare for this work.

Abstract
Atopic dermatitis is a common cutaneous disease with significant morbidity affecting children and adults. The mainstay of atopic dermatitis therapy has typically included emollients, topical corticosteroids, and topical calcineurin inhibitors. Among the newer advances recently introduced is crisaborole (Eucrisa™), a phosphodiesterase type-4 inhibitor (PDE-4) for the treatment of mild moderate atopic dermatitis. Evidence from phase 3 trials demonstrates crisaborole as an efficacious topical agent with a favorable safety profile and limited systemic exposure. While the efficacy of crisaborole compared to existing therapies remains unknown, crisaborole is a promising candidate in the treatment of atopic dermatitis.

Key Words:
atopic dermatitis, crisaborole, eczema, Eucrisa, phosphodiesterase-4 inhibitor, topical treatment

Introduction

Atopic dermatitis (AD) is a chronic inflammatory cutaneous condition associated with significant morbidity and stigma in affected patients.¹ AD is characterized by the sudden onset of a recurrent, pruritic, erythematous and fissured dermatoses. It is estimated to affect up to 15-30% of children and up to 10% of adults living in industrialized countries.² In the United States alone, AD imposes a considerable economic burden, with an estimated cost of up to $3.8 billion annually.^1,3 Clinical features differ with age. The flexural surfaces of upper and lower extremities and face are most often affected during childhood, whereas hands and feet are more commonly involved in adult patients.⁴ AD can be associated with serious comorbidities including allergic rhinitis, asthma, hay fever, urticaria and asthma.^3,5 Patients with genodermatoses, such as Wiskott-Aldrich syndrome, may show an AD like skin condition.⁶ Individuals with AD are more prone to cutaneous secondary infections by pathogens including Staphylococcus aureus, which is also a leading cause of soft-tissue infections. Moreover, secondary skin infection can lead to exacerbation of AD disease severity.⁷

As the frequency of AD continues to rise, renewed focused on treatment and management is increasingly important.¹ As no curative options exist, therapy centers on controlling disease progression, reducing flares and providing relief from symptoms, including pain and pruritus.^8,9 The mainstays of such therapies include the use of emollients, cosmeceuticals, topical and systemic corticosteroids, as well as topical calcineurin inhibitors (TCIs).² Treatment options are predicated on age and AD severity. For instance, mild to moderate AD may be treated with TCIs or corticosteroids such as desonide 0.05% or fluocinolone 0.01%.⁸ In patients with moderate to severe AD who are recalcitrant to topical therapy, systemic treatment may include dupilumab administered at 300 mg subcutaneously once weekly or every other week for adults.^10,11 Proactive therapy with tacrolimus 0.1% ointment or pimecrolimus 2% twice daily⁹ may be employed to prevent relapses and extend periods without recurrence in patients who experience frequent exacerbations. TCIs have been issued a black box warning based on theoretical concerns that their use may be linked to lymphoma,¹² however, long-term surveillance has not substantiated this risk. Moreover, prolonged use of topical corticosteroids has been associated with cutaneous atrophy, telangiectasia, and striae formation.⁸ This has led to the development of new therapies, particularly aimed at the pediatric population. Crisaborole (formerly known as AN2728) is a novel, boron-based phosphodiesterase-4 (PDE-4) inhibitor developed to treat this populace.^8,13

A Novel Treatment for Mild-Moderate AD

Crisaborole (Eucrisa™) 2% ointment is indicated as a topical treatment for patients aged ≥2 years with mild to moderate AD. Early phase 1 and 2 studies provided evidence that showed the potential for crisaborole to be an efficacious and noncarcinogenic treatment option with a positive safety profile.^14-16 Approved in December of 2016 by the US FDA and June 2018 by Health Canada, it is the first topical PDE-4 inhibitor to be indicated for AD.

Mechanism of Action

In patients with AD, elevation of PDE-4 is associated with increased inflammatory mediators leading to a chronic inflammatory state.¹⁷ PDE-4 facilitates this inflammatory process through the degradation of 3’5’-cyclic adenosine monophosphate (cAMP). Crisaborole works through the selective inhibition of PDE-4, preventing the breakdown of cAMP, leading to an accumulation of cellular cAMP, suppression of pro-inflammatory cytokines, and reduction in inflammatory pathways.^8,17,18 Specifically, elevated levels of cAMP result in further activation of protein kinase A and inhibition of nuclear factor κB (NF-κB) and nuclear factor of activated T-cells (NFAT) signaling pathways. Crisaborole targets the underlying mechanism of the disease through suppression of pro-inflammatory cytokines, including interleukin (IL)-2, IL-5, interferon-γ, and tumor necrosis factor-α.^17-19 Of note, this mechanism of cytokine-production inhibition by crisaborole is distinct from that of corticosteroids.¹⁷

Phase 3 Clinical Trials

The efficacy and safety of crisaborole was evaluated through two randomized, double-blind controlled phase 3 clinical trials, which included a total of 1522 patients ≥2 years of age with mild to moderate AD.²⁰ Although both pediatric and adult patients were represented in the study population, the mean age of the crisaborole ointment treatment groups was 12 and 12.6 in both studies. Adult patients (≥18 years of age) constituted 12.9% and 15% of the crisaborole treatment groups. The efficacy of crisaborole within these studies was determined by the clearance or almost clearance of AD with a 2-grade or more improvement from baseline using the Investigator’s Static Global Assessment (ISGA). In both studies, more crisaborole-treated patients showed improvement in the ISGA score at day 29 (32.8%, 31.4%) as compared against vehicle-treated patients (25.4%, 18%), respectively. Furthermore, patients in the crisaboroletreated group achieved success in the ISGA score earlier than the control. Pooled data between the two studies demonstrated an improvement in disease severity, as measured by the reduction in signs and symptoms, including erythema, exudation, excoriations, induration/papulation and lichenification. Improvement and sustained relief of pruritus was achieved earlier in crisaboroletreated patients (1.37 vs. 1.7 days, p=0.001).²⁰ A secondary analysis of the phase 3 trials performed by Yosipovitch et al.21 confirmed the early improvement in pruritus for the treatment cohort compared to control (56.6% vs. 39.5%; p<0.001).

Safety and Long-term Complications

Unlike topical corticosteroids and calcineurin inhibitors, which have potential adverse side effects with continued use, crisaborole demonstrates a promising safety profile. Crisaborole effectively penetrates through the skin due to its low molecular weight (251 Da) and lipophilic properties,¹⁷ with only trace amounts reaching the systemic circulation.²² Steady-state levels of crisaborole and its metabolites were reached in a pharmacokinetic 8-day trial under maximal-use conditions.²² In this study, the mean maximum plasma concentration of crisaborole remained stable with a mean maximum concentration of 127 ng/mL seen on day 8. Once in the bloodstream, the drug is quickly metabolized into inactive metabolites, limiting the systemic impact of crisaborole to the site of application.^17,22 Whereas nausea, emesis, and/or diarrhea are side effects associated with oral PDE-4 inhibitors, similar symptoms are uncommonly observed with topical use.^20,23,24 The majority of adverse events include burning or stinging at the site of application.²⁰ Of these adverse events, 77.6% of patients experienced resolution within 1 day of onset. No serious adverse events were recorded. Lastly, the low discontinuation rates (1.2%, pooled data) that were observed in phase 3 trials may indicate the potential for higher treatment compliance.

After completion of a 28-day phase 3 pivotal study, a longitudinal multicenter, open-label trial was conducted that followed 517 patients over 48 weeks to assess the long-term safety of crisaborole.²⁴ Only 10.3% of patients experienced treatmentrelated adverse events. Of these, the vast majority of adverse events were considered mild (51.2%) or moderate (44.6%). The most common events reported were atopic dermatitis (3.1%), application-site pain (2.3%) and application-site infection (1.2%). No change in the frequency of adverse events was observed throughout the study. Rescue therapy with a topical corticosteroid or TCI was required in 22.2% of patients, with the majority (79%) resuming crisaborole after the end of rescue therapy.

Conclusion

Crisaborole represents a novel and efficacious therapeutic approach for the treatment of mild to moderate AD. Through the inhibition of PDE-4 and reduction of local inflammation, crisaborole has been shown to provide a significant improvement in the management of AD.^14-16,20,22 Furthermore, crisaborole demonstrates early and continued decrease in pruritus, which improves quality of life and reduces the potential risk of infection and scarring.^24,25 The small size of the crisaborole molecule allows for effective skin penetration, while its quick metabolism in the bloodstream limits systemic exposure, which is associated with the long-term use of topical corticosteroids and TCIs.²² Further studies comparing crisaborole against topical corticosteroids or TCIs are warranted to establish it role in the treatment paradigm for mild to moderate AD, as well as its utility in children <2 years of age.

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