Long-term use of a new topical formulation containing piroxicam 0.8% and sunscreen: efficacy and tolerability on actinic keratosis. A proof of concept study

INTRODUCTION: Cyclooxygenase (COX) 1 and 2 enzyme up-regulation is involved in the pathogenetic process of actinic keratosis (A.K.) and non-melanoma skin cancers. Diclofenac, a non-steroidal anti-inflammatory (N.S.A.I.D.) drug, is used as topical treatment of A.K. Piroxicam is a N.S.A.I.D. characterized by a high COX-1 inhibition activity. STUDY AIM: We conducted an 18 month exploratory open-label study on A.K., to assess the efficacy and tolerability of a new topical formulation of piroxicam and sunscreen in A.K. PATIENTS: Enrolled subjects applied a galenic formulation of piroxicam 0.8%, vehiculated in a topical product containing sun filters with high (50+) and broad spectrum (UVA) actions, twice a day for 6 months. Subjects were then followed up for additional 12 months. Thirty-eight subjects with a total of 69 A.K. lesions participated in the trial. The primary outcome was the evolution of the Actinic Keratosis Erythema Scale Atrophy (A.K.E.S.A) score assessing erythema, scale, and atrophy of a target A.K. lesion. Secondary outcomes were the percentage of treated lesions with complete (100%) or partial (≥75%) clearance and the evaluation skin tolerability. RESULTS: A.K.E.S.A. mean (S.D.) score at baseline was 7.5 (1.2). After 6 months of treatment, A.K.E.S.A. score decreased to 0.9 (1.1), a -88% reduction versus baseline. At the end of follow-up, A.K.E.S.A. score was 0.8 (1.2). A complete response was achieved in 38 of the 69 lesions (55%, 95% C.I.: 43% to 66%) and clearance was maintained 1 year post-treatment. A partial clearance was observed in 57 of 69 treated lesions (83%, 95% C.I.: 73% to 91%). Adverse events were limited to mild local irritation. CONCLUSION: Our experience suggests that 6 month topical piroxicam 0.8% is efficacious and well tolerated in A.K. Clinical efficacy is maintained 1 year post-treatment. The main limitation of our study is that it was an open label non-controlled trial. Future controlled trials are warranted in order to compare the efficacy and tolerability of this topical piroxicam preparation with standard treatments in the management of A.K.