ABSTRACT
Epidermal growth factor receptor (EGFR) inhibitors are an increasingly important treatment option for metastasized cancer in patients. In addition to the pivotal role of EGFR in the development and progression of malignant tumors, EGFR is also important for proliferation and differentiation of the human epidermis and hair follicles. As a consequence, cutaneous side-effects are frequently observed during cancer therapy with EGFR inhibitors. During the first few weeks of treatment, acneiform eruptions are the earliest common side-effect. Xerosis and fissures are complications appearing in later treatment phases. Paronychia and alterations in hair growth are less common and generally seen after a longer period of treatment. We present an overview of the various cutaneous side-effects associated with EGFR inhibition and discuss their respective therapeutic options.

Key Words:
anti-EGFR, epidermal growth factor receptor inhibitors, cutaneous side-effects, acneiform eruption, paronychia, xerosis, management

The epidermal growth factor receptor (EGFR), a 170-kd transmembrane glycoprotein, is a member of the type 1 receptor tyrosine kinase (TK) family. The EGFR is physiologically expressed in epithelial tissues and hair follicles, where it contributes to epidermal proliferation, differentiation, and hair growth. In addition, EGFR is overexpressed in many solid tumors, where it is involved in tumor growth, cell proliferation, apoptosis, angiogenesis, cell motility, and metastasis.¹ Preclinical and clinical studies have shown that inhibiting EGFR is a valid strategy in anticancer therapy.^1,2

Different strategies for EGFR inhibition have been described,³ two of which entered routine clinical use: EGFR-targeting monoclonal antibodies (MoAbs) bind specifically to the extracellular domain of the receptor and competitively inhibit ligand binding,¹ and tyrosine kinase inhibitors suppress EGFR signaling at the intracellular domain of the receptor.¹ Experimental data exist for EGFR ligand toxin and EGFR immunotoxin conjugates. These novel drugs are composed of an EGFR ligand or EGFR-binding antibody and a cytotoxic agent. Finally, antisense oligonucleotides specific for the EGFR or EGFR ligand messenger ribonucleic acids (RNAs) may decrease EGFR expression, thus resulting in inhibition of proliferation and induction of apoptosis.

As of July 2010, there are two monoclonal antibodies (cetuximab, Erbitux® and panitumumab, Vectibix®) and one receptor tyrosine kinase inhibitor (Gefitinib, Iressa®) that are currently licensed for clinical use in many countries.¹ Gefitinib is a historic tyrosine kinase inhibitor that did not show significant survival benefit.⁴ Lapatinib (Tykerb®/Tyverb®) and canertinib (CI-1033) are currently developed tyrosine kinase inhibitors.^4-5 Lapatinib is under investigation for the second-line treatment of metastatic colorectal cancer, whereas canertinib is being studied for progressive, recurrent, locally advanced or metastatic non-small cell lung carcinoma, and metastatic breast cancers.^6,7

The safety profile of EGFR-inhibitors is characterized by a class effect comprised of unique skin reactions, including acneiform rash, xerosis, eczema, paronychia, and changes in the hair and nails.⁸ Hyperpigmentation, trichomegaly, and telangiectasia are less commonly seen. EGFR inhibitor-induced urticarial and anaphylactoid reactions are frequently seen in the US, but these are rarely encountered in Europe.^9-10 Here, we review the diagnostic procedures and current treatment options for the more common side-effects of EGFR inhibitors.^4,8,11-16

Acneiform Eruptions

Acneiform eruptions are the earliest and most characteristic side-effect of EGFR inhibition. The incidence may be as high as 75% to 100% of cases.^{2,4,8,14,16-19} Evidence suggests that severity of the skin rash might be a surrogate marker determining clinical outcome of patients receiving EGFR inhibitor treatment.^1,19-21 The eruption usually occurs after 1 week of treatment. The characteristic distribution pattern is similar to that of acne vulgaris, but there are no comedones present. Although these eruptions are considered a class effect from EGFR inhibition, antibody-induced eruptions tend to be more severe than TK1 induced skin changes.⁴

The pathogenesis of acneiform eruptions caused by EGFR is not yet fully understood. Histopathological analysis showed a neutrophilic suppurative infiltrate in the dermis, particularly involving the follicular infundibula. The follicles are frequently enlarged and sometimes obstructed by excess keratinocytes. The sebaceous glands are usually not affected. No consistent changes in the cutaneous microflora have been found.⁴

Grading of acneiform eruptions is performed with two different scoring systems, depending if quick severity classification or sensitive follow-up of treatment success is the goal of grading. The oncological classification, National Cancer Institute Common Toxicity Criteria for Adverse Events, version 4.0, allows for a quick severity estimation of skin toxicity reactions. It provides a clinical score with five grades of severity.⁴ The dermatological skin score (WoMoScore) is a sensitive dermatologic scoring system for the long-term assessment of acneiform skin rashes that has been used in our department since 2006.²² The final WoMoScore is calculated from body involvement, facial involvement, and clinical grading of erythema, papulation, postulation, scaling, and crusts, providing a clinical score ranging from 0 to 100.²² Mild skin changes score up to 20, moderate cases range between 20 and 40, whereas severe acneiform eruptions exceed a WoMoScore of 40.²⁰

Treatment of Acneiform Eruptions

Treatment of mild acneiform eruptions mostly involves
conventional topical medications used for acne vulgaris, such as metronidazole, erythromycin, and clindamycin.^4,8

Topical combination therapy with nadifloxacin 1% cream and prednicarbate 0.25% cream is our standard regimen for moderate acneiform eruptions.²² An uncontrolled, open label, follow-up study involving 29 cancer patients with cetuximab- induced acneiform eruptions initially demonstrated clinical efficacy with significant reduction of the WoMoScore after 1,
2 and 6 weeks of therapy.²² Both drugs were selected because nadifloxacin has antimicrobial as well as immunomodulatory effects on the antigen-presenting function of Langerhans cells and keratinocytes,²³ and prednicarbate is a well established anti-inflammatory topical corticosteroid with an improved risk- benefit ratio.²⁴

Preclinical data suggest that topical application of the potent phosphatase inhibitor menadione (vitamin K3) might rescue the inhibition of EGFR and downstream signaling molecules in the skin of mice receiving systemic EGFR inhibitors erlotinib (Tarceva®) or cetuximab.²⁵ In a non-randomized study with
30 patients, acneiform eruptions were reduced significantly by the topical use of a cream containing urea and 0.1% K1 vitamin (Reconval K1®).²⁶

Oral tetracyclines have been used for the treatment of acne vulgaris for more than 50 years²⁷ because of their anti- inflammatory and immunomodulatory properties.^28-30 These broad-spectrum polyketide antibiotics reduce neutrophilic chemotaxis and inhibit the production of proinflammatory cytokines and matrix metalloproteinase 9.²⁹ Some recent studies investigated the benefit of prophylactic tetracycline for EGFR- induced acneiform eruptions.^31-32 Tetracycline-treated patients reported less itching, burning, stinging, and other subjective symptoms compared with placebo. However, prophylactic tetracyclines did not lower the total incidence of the rash.^31-32

Tetracyclines are clearly effective, but they may lead to unwanted systemic effects that are not encountered with topical treatment.
Our first choice for severe acneiform eruptions is early treatment with a combination of low dose oral retinoid, topical nadifloxacin, and topical prednicarbate.^21-22 We limit the use of this highly effective “triple therapy” to the first 2-3 months of EGFR- inhibitor treatment.21 Some authors have raised the issue of increased xerosis or reduced anticancer properties of the EGFR- inhibitors, ^5,10,11 whereas others see a potential synergistic effect of this combinatorial approach.¹¹

Management of acneiform skin eruptions is influenced by the level of dermatological background of the treating physician.³³
Dermato-oncologists are using oral isotretinoin more frequently, compared with oncologists, and are delaying EGFR inhibitor treatment less frequently because of skin toxicities.³³ An interdisciplinary approach in cooperation with dermatologists is highly recommended to improve patient treatment.^8,33

Paronychia

EGFR inhibitor-induced paronychia is seen in about 10% to 15% of all treated patients and may be quite painful, adversely affecting their quality of life.¹² It generally does not develop during the first 6 weeks of treatment. Patients frequently present with involvement of the great toenails. Fingernail involvement may lead to significant functional impairment. Periungual abscesses and pyogenic granuloma may develop in some cases.^4,8,15 A recent study showed that a wide variety of Gram-positive and Gram- negative bacteria, as well as Candida albicans, may be cultured from the nail lesions.¹⁵

Initial stages of paronychia should be treated with topical antiseptic measures and application of antiseptic or antibiotic ointments. Antiseptic treatment should be continued after systemic therapy has been initiated. Systemic treatment of paronychia is recommended for all painful or infected lesions, as there is a risk for the development of erysipelas, deep panaritium, and tendon sheath phlegmon. Calculated antibiotic treatment of paronychia is recommended with oral cephalosporines, but oral fluoroquinolones may also be used, especially if Gram-negative infection is suspected. Surgical intervention may be necessary in selected cases, such as ingrown toe nails.^4,8,15

Xerosis

Xerosis is also considered a class effect of EGFR inhibitors, as it affects most treated patients to a variable degree. Xerosis typically presents as dry, scaly, itchy skin that can be found on any part of the human body. Some patients may also experience dryness of vaginal and perineal regions. Xerosis may progress to chronic asteatotic eczema and become infected with Staphylococcus aureus or herpes simplex virus. Severe cases of pulpitis sicca (dry skin on the tips of the fingers and toes) with painful rhagades have also been described.^4,8

First-line treatment of xerosis is the liberal use of emollients, which should be started within the first days of initiating EGFR inhibitor treatment. This prophylactic approach is safe and effective, and may prevent the onset of eczema. ^4,8

Rhagades

Painful fissures on the tips of fingers and toes, on the nailfolds, and especially over the interphalangeal joints may develop as a consequence of excessively dry skin. Fissures are less common late phase reactions from therapy with EGFR inhibitors. They occur in about 25% of patients and are characterized by pain, severe tenderness, and poor healing tendency.^4,8 Fissures are challenging to treat. Silver nitrate solution, creams containing urea under plastic occlusion, and topical antibiotics can be used. Liquid cyanoacrylate glue may be tried for recurrent cases.^4,8

Further Cutaneous Side-effects

Trichomegaly, with or without additional hypertrichosis, may develop after 2 to 5 months of continuous anti-EGFR treatment. Trichomegaly may cause visual discomfort, but can be effectively treated by trimming the eye lashes. The higher expression of EGFR in the outer root sheath of the hair follicles may be causative for this infrequent but characteristic side-effect.^4,8,12

Hyperpigmentation may appear after several months of EGFR inhibitor therapy. As bleaching creams have not been shown to be effective, patients must wait for the hyperpigmentation to fade over several months.^4,12

Telangiectasias may occur together with acneiform eruptions and follow the same pattern on the face and trunk. These telangiectasias vanish with time, but often leave some degree of hyperpigmentation.^4,12

Painful aphthae and larger erosions may appear on the oral mucosa, lips, and nose, as well as on the anal and genital mucosa. Localized measures that are pain-relieving and soothing will provide considerable symptomatic relief.

Patients must be warned to stay out of the sun, because photosensitivit y is increased during therapy with EGFR inhibitors and quite severe acneiform reactions can be triggered by UV exposure. Consequently, the prophylactic use of sunscreens is highly recommended to prevent these solar-induced reactions.

Conclusion

EGFR inhibitors are associated with a unique group of class- specific cutaneous toxicities, which include acneiform eruptions, paronychia, xerosis, hyperpigmentation, trichomegaly, and telangiectasia. As the use of EGFR inhibitors increases, a growing number of cutaneous side-effects will be treated by dermatologists. The discomfort caused by the cutaneous toxicities can reduce compliance with anti-EGFR therapy. For this reason, consequent treatment and psycho-dermatological support are very important. Almost all side-effects are temporary and will resolve several weeks after discontinuation of EGFR inhibitor therapy. It is import to educate patients about these side-effects, in order to increase compliance.

References

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2. Cunningham D, Humblet Y, Siena S, et al. Cetuximab monotherapy and cetuximab plus irinotecan in irinotecan-refractory metastatic colorectal cancer. N Engl J Med 351(4):337-45 (2004 Jul 22).
3. Mendelsohn J, Baselga J. The EGF receptor family as targets for cancer therapy. Oncogene 19(56):6550-65 (2000 Dec 27).
4. Hu JC, Sadeghi P, Pinter-Brown LC, et al. Cutaneous side effects of epidermal growth factor receptor inhibitors: clinical presentation, pathogenesis, and management. J Am Acad Dermatol 56(2):317-26 (2007 Feb).
5. Saltz LB, Meropol NJ, Loehrer PJ, Sr., et al. Phase II trial of cetuximab in patients with refractory colorectal cancer that expresses the epidermal growth factor receptor. J Clin Oncol 22(7):1201-8 (2004 Apr 1).
6. Burris HA, 3rd, Taylor CW, Jones SF, et al. A phase I and pharmacokinetic study of oral lapatinib administered once or twice daily in patients with solid malignancies. Clin Cancer Res 15(21):6702-8 (2009 Nov 1).
7. Arora A, Scholar EM. Role of tyrosine kinase inhibitors in cancer therapy. J Pharmacol Exp Ther 315(3):971-9 (2005 Dec).
8. Wollenberg A, Kroth J, Hauschild A, et al. [Cutaneous side effects of EGFR inhibitors– appearance and management]. Dtsch Med Wochenschr 135(4):149-54 (2010 Jan).
9. Chung KY, Shia J, Kemeny NE, et al. Cetuximab shows activity in colorectal cancer patients with tumors that do not express the epidermal growth factor receptor by immunohistochemistry. J Clin Oncol 23(9):1803-10 (2005 Mar 20).
10. 10. Segaert S, Tabernero J, Chosidow O, et al. The management of skin reactions in cancer patients receiving epidermal growth factor receptor targeted therapies. J Dtsch Dermatol Ges 3(8):599-606 (2005 Aug).
11. Gutzmer R, Werfel T, Kapp A, et al. [Cutaneous side effects of EGF-receptor inhibition and their management]. Hautarzt 57(6):509-13 (2006 Jun).
12. Klein E, Tietze J, Wollenberg A. Unerwünschte kutane arzneimittelwirkungen von EGF-rezeptor-antagonisten und deren behandlung. Allergo J 15:559-65 (2006).
13. Bierhoff E, Seifert HW, Dirschka T. [Cutaneous lesions due to inhibition of epidermal growth factor receptor]. Pathologe 27(1):53-6 (2006 Feb).
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15. Eames T, Grabein B, Kroth J, et al. Microbiological analysis of epidermal growth factor receptor inhibitor therapy-associated paronychia. J Eur Acad Dermatol Venereol 24(8):958-60 (2010 Aug).
16. Molinari E, De Quatrebarbes J, Andre T, et al. Cetuximab-induced acne. Dermatology 211(4):330-3 (2005).
17. Burtness B, Goldwasser MA, Flood W, et al. Phase III randomized trial of cisplatin plus placebo compared with cisplatin plus cetuximab in metastatic/recurrent head and neck cancer: an Eastern Cooperative Oncology Group study. J Clin Oncol 23(34):8646-54 (2005 Dec 1).
18. 18. Segaert S, Van Cutsem E. Clinical signs, pathophysiology and management of skin toxicity during therapy with epidermal growth factor receptor inhibitors. Ann Oncol 16(9):1425-33 (2005 Sep).
19. Eames T, Kroth J, Flaig MJ, et al. Perifollicular xanthomas associated with epidermal growth factor receptor inhibitor therapy. Acta Derm Venereol 90(2):202-3 (2010 Mar).
20. Wollenberg A, Moosmann N, Klein E, et al. A tool for scoring of acneiform skin eruptions induced by EGF receptor inhibition. Exp Dermatol 17(9):790-2 (2008 Sep).
21. Wollenberg A, Moosmann N, Kroth J, et al. [Therapy of severe cetuximab-induced acneiform eruptions with oral retinoid, topical antibiotic and topical corticosteroid]. Hautarzt 58(7):615-8 (2007 Jul).
22. Katzer K, Tietze J, Klein E, et al. Topical therapy with nadifloxacin cream and prednicarbate cream improves acneiform eruptions caused by the EGFR-inhibitor cetuximab – A report of 29 patients. Eur J Dermatol 20(1):82-4 (2010 Jan-Feb).
23. Murata K, Sugita K, Kobayashi M, et al. Nadifloxacin downmodulates antigen- presenting functions of epidermal Langerhans cells and keratinocytes. J Dermatol Sci 42(2):91-9 (2006 May).
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27. Lane P, Williamson DM. Treatment of acne vulgaris with tetracycline hydrochloride: a double-blind trial with 51 patients. Br Med J 2(5649):76-9 (1969 Apr 12).
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29. Sapadin AN, Fleischmajer R. Tetracyclines: nonantibiotic properties and their clinical implications. J Am Acad Dermatol 54(2):258-65 (2006 Feb).
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31. Jatoi A, Rowland K, Sloan JA, et al. Tetracycline to prevent epidermal growth factor receptor inhibitor-induced skin rashes: results of a placebo-controlled trial from the North Central Cancer Treatment Group (N03CB). Cancer 113(4):847-53 (2008 Aug 15).
32. Scope A, Agero AL, Dusza SW, et al. Randomized double-blind trial of prophylactic oral minocycline and topical tazarotene for cetuximab-associated acne-like eruption. J Clin Oncol 25(34):5390-6 (2007 Dec 1).
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Hautklinik, Universitätslinikum Düsseldorf, Heinrich-Heine University, Düsseldorf, Germany

ABSTRACT

The role of photodynamic therapy (PDT) in the treatment of in situ neoplasias and tumors of the skin is steadily increasing. Its principles of photodynamic action include an intratumoral enriched photosensitizer and light activation. Aminolevulinic acid (ALA) has demonstrated highest efficacy in topical PDT, and has become the most clinically useful. For actinic (solar) keratoses, topical ALA-PDT using Levulan® Kerastick™ (20% topical solution, DUSA Pharmaceuticals) is already postulated to be the treatment of choice. In December 1999, the US FDA approved this topical product for the treatment of actinic keratoses. Levulan® is well tolerated and leads to excellent cosmetic results with only minor side effects.

Key Words:
aminolevulinic acid, porphyrins, photosensitizer, photodynamic therapy, actinic keratoses

δ-Aminolevulinic acid HCl is an endogenous precursor of highly photosensitizing porphyrin metabolites. Normally, the synthesis of ALAis tightly controlled by feedback inhibition of the enzyme aminolevulinic acid synthase (ALA-S), presumably by intracellular heme levels.^1,2 Therefore, when exogenous ALA is provided to the cell through topical application, protoporphyrin IX accumulates by bypassing the rate limiting enzyme ALA-S.

In photodynamic therapy (PDT), light absorption by porphyrin metabolites, e.g., protoporphyrin IX, results in an excited state of the molecule and subsequent generation of reactive oxygen species, which can react further to form superoxide and hydroxyl radicals.³ The tissue-specific phototoxic effects resulting from local application of ALA and light irradiation are the basis of photodynamic therapy (PDT) for actinic keratoses (AKs) and other in situ neoplasias.

Pharmacology of ALA

The standard procedure of topical ALA-PDT for skin tumors involves the application of 10-20% ALA in an oil-in-water emulsion, which is then covered by an occlusive dressing to enhance the tissue penetration of the drug and to prevent undesired photobleaching of porphyrins by visible light.

Levulan® Kerastick™

ALA has been pharmaceutically included into Kerastick™ (20% topical solution, DUSA Pharmaceuticals).^4,5 Each Kerastick™ applicator has 2 sealed glass ampules containing 1.5ml hydroalcoholic solution vehicle and 354mg ALA. Schering AG, Berlin officially applied for Levulan® Kerastick™ to be used for the treatment of AK in Austria in 2001. Austria is acting as a reference member state for the European application. In the US it is marketed by Berlex Laboratories on behalf of DUSA.

Adverse-effects

Contraindications for PDT include cutaneous photosensitivity, porphyria, and allergies to ALA or to any of its components. Patients who have concomitant disorders that are provoked or aggravated by light should be evaluated cautiously. It is not known whether ALA or its metabolites are excreted in breast milk, therefore, caution should be exercised when treating women who are breastfeeding.

Following topical application of ALA, the treated site becomes photosensitive, and patients should be warned to avoid sunlight or bright indoor light (e.g., examination lamps, theater lamps, tanning beds, or lights at close proximity). Such exposure may result in a stinging and burning sensation and cause erythema and/or edema of the lesions.^2,6 Topical ALA treatment does not induce systemic accumulation of ALA or porphyrins.⁷

As a result of light exposure during PDT treatments, patients may experience burning pain, stinging, or itching, which is restricted to the illuminated area.^8-10 The discomfort will peak within the first minutes of irradiation. It may continue for several hours, though in a decreasing manner. Local anesthesia or intensive cooling can help to control the pain, especially when disseminated, large, ulcerative, or inflamed areas are treated.

The normal course of clinical response to PDT is usually distinguished by crusting, scaling, pruritus, and healing within 1-4 weeks.¹⁰ Urea preparations can be used to resolve dry crusts and accelerate re-epithelialization.^11,12 ALA produces very good cosmetic results, often superior to the outcome achieved by cryosurgery¹³, surgery, or topical chemotherapy. Generally, scar formation is minimal or absent. Rarely, residual hyperpigmentation or hypopigmentation of the treated area can occur.

Pharmacokinetics

The application of ALA in PDT for cutaneous disorders was introduced in 1990.¹⁴ The main advantage of this treatment is the absence of generalized cutaneous photosensitivity. The mechanisms of ALA uptake and accumulation in malignant and regenerative cells are not completely understood. Major responsibility for the tumor selectivity of ALA or synthesized porphyrins is the increased permeability of abnormal keratin layers in epithelial skin tumors. The active transport of the compound through plasma membranes was demonstrated in microorganisms and in cell culture.¹⁵ However, additional celltype dependent uptake mechanisms cannot be excluded. The optimal application time and concentration have already been elucidated by biochemical analyses of ALA-treated skin samples. Epithelial skin tumors such as basal cell (BCC) or squamous cell carcinomas (SCC) reveal maximum porphyrin levels 2-4 hours after topical ALA application.⁶

Light sources

In dermatology, the most commonly used irradiation sources include incoherent light sources that comprise red (570-750nm),⁹ green (545nm),¹⁰ or blue light (417nm,¹⁶ or 400-410nm¹⁷) and laser systems (e.g., argon pumped dye lasers). BLU-U™ has a nominal peak value of 417nm with a spectral range of 402- 432nm.¹⁸

Clinical Trials

In 1990, the topical application of 20% ALA to AKs, followed by a single exposure to the light of a filtered slide projector, resulted in a complete response (CR) of 90%.¹⁴ In the following years, other investigators, using more professional incoherent light sources, obtained a CR of 80-100% in AKs.^19-21 The CR rate of AKs located on the face and scalp was significantly higher (91%) when compared with keratoses on the trunk and extremities (45%). The often reported poor clinical response (<30%) of the thick hyperkeratotic lesions⁵ may have been due to ineffective penetration of ALA and consecutive insufficient production of porphyrin molecules.

In a randomized, multicenter, vehicle-controlled, investigatorblinded, light-dose ranging study, maximal therapeutic effects were obtained in ALA-treated AKs irradiated with blue light (BLU-U™, 417 nm) at a dose of 10J/cm² (10 mW/cm²).16 ALA solution (20%) or the vehicle only was applied to 2 lesions each, on the face and scalp of 36 patients. Lesions were exposed to 2, 5 or 10J/cm² of blue light (417nm) delivered at 3, 5 or 10mW/cm2, 14-18 hours after application. Eight weeks after treatment a CR was obtained in 66% of ALA-treated lesions versus 17% of those treated with vehicle and light (p < 0.001). The maximal response (80%) was seen in patients treated with the maximal dose of light (10 J/cm²). Non-responding lesions were re-treated at 8 weeks and by 16 weeks the CR was 85% in ALA-treated lesions. The efficacy of the higher light dose was confirmed in a second phase II study of 64 patients conducted with the same protocol.¹⁶

To establish the optimum concentration of ALA solution, a randomized, vehicle-controlled, investigator-blinded, multicenter study was carried out using ALA 2.5, 5, 10, 20, or 30% wt/vol and blue light (BLU-U™) at 10 J/cm² (10 mW/cm²).¹⁶ ALA was applied to lesions (site not specified) on 124 patients. There were significantly more CR (defined as clearance of 75% of lesions) in the groups treated with 10, 20 or 30% ALA than in the groups treated with 2.5 or 5%. A dose-response trend was evident with a plateau emerging at the 10, 20 and 30% dose levels. The researchers concluded that an ALA concentration of 20% produced the best response.

In phase III trials topical ALA 20% was effective in eradicating AKs of the face and scalp in the majority of patients. A total of 241 patients with 4-15 AKs each were enrolled in two randomized, vehicle-controlled, investigator-blinded, multicenter trials²² (see Table 1).

Table 1: Clinical Trial results using Levulan® and BLU-U™.
*Maximal response was seen in patients treated with the maximal light dose (10J/cm²).
**All patients showed multiple lesions. The clearance rate was higher for lesions on the face (78%) than on the scalp (50%).

Conclusion

Levulan® and BLU-U™ are very effective in the treatment of AKs. It is non-invasive and leaves the patients with excellent cosmetic results. The response of AKs to PDT equals the cure rates achieved by other topical treatment modalities, including the use of liquid nitrogen and chemical peels. In summary of the current data, ALA-PDT appears to be most efficient for the treatment of these in situ neoplasias.

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