Long-term follow-up of a randomized, double-blind, phase III, multi-centre study to evaluate the safety and efficacy of field-directed photodynamic therapy (PDT) of mild to moderate actinic keratosis using BF-200 ALA versus placebo and the BF-RhodoLED® lamp

In actinic keratosis (AK), field cancerization describes areas of skin where multiple visible AK lesions are surrounded by healthy looking skin containing non-visible (subclinical) lesions. As all AK lesions have a risk of progression to cutaneous squamous cell carcinoma, experts advise field-directed treatment. Photodynamic therapy (PDT) is an effective field-directed treatment option for AK; however, long-term efficacy data are still scarce. This publication presents follow-up data of a phase III study evaluating the efficacy and safety of field-directed PDT. The study was conducted in seven centres in Germany. For PDT, participants with AKs on the face and scalp (treatment area of 20 cm ) had received up to two field-directed PDTs using BF-200 ALA or placebo, and illumination with narrow-spectrum red light. Only participants or lesions with complete response 12 weeks after the last PDT were assessed for recurrences. The treatment area was evaluated 6 and 12 months after the last PDT for recurrence, cosmetic outcome and new lesions. Fifty-four participants in the BF-200 ALA and 30 in the placebo group entered the follow-up. The probability of a participant to be initially completely cleared and to remain cleared for 12 months was 57.4% for BF-200 ALA versus 20.0% for placebo. The probability of a lesion to be initially cleared and remain cleared for 12 months was 85.4% for BF-200 ALA versus 31.5% for placebo. 83.3% of participants with cosmetic impairment at baseline rated the cosmetic outcome 12 months after PDT with BF-200 ALA as very good or good. All parameters of skin quality further improved during follow-up. We showed that effectiveness of field-directed PDT with BF-200 ALA and narrow-spectrum red light was maintained during follow-up. Based on our results, field-directed PDT is a beneficial long-lasting treatment for AK patients. 2013-002510-12 (EudraCT); NCT01966120 (Clinicaltrials.gov).