Efficacy Endpoints in Clinical Trials in Actinic Keratosis

INTRODUCTION: Actinic keratosis is regarded as a chronic disease of the skin and, although fluctuating, is chronically progressive. Approval of new products for the treatment of actinic keratosis requires the use of a standard methodology in clinical trials which emphasize complete clearance of all actinic keratoses in a treatment field in a defined time span and the evaluation of long-term efficacy in terms of recurrence rate among completely cleared patients. METHODS: Analysis of data from six previously published clinical trials in patients with actinic keratosis. RESULTS: There was poor agreement over a period of 1 month in the complete clearance endpoint. This variation in assessment renders recurrence in cleared patients invalid as the estimate of long-term efficacy. Furthermore, complete clearance was shown to depend heavily on the number of baseline actinic keratoses. CONCLUSION: The main endpoints presently in use for the assessment of short- and long-term efficacy of actinic keratosis field-directed therapy, namely, complete clearance and recurrence rate, are obsolete and should be replaced by the percentage reduction in actinic keratosis count or the absolute actinic keratosis count. FUNDING: LEO Pharma A/S.