Long-term sustained lesion clearance from Lmax with imiquimod 3.75%, a new field-directed treatment for actinic keratosis.

BACKGROUND In patients with actinic keratosis (AK), subclinical and clinical lesions coexist across large areas of sun-exposed skin. The long-term efficacy of AK treatments depends on their ability to eradicate both types of lesions across the entire field. OBJECTIVE To assess the long-term efficacy of imiquimod 3.75% using the reduction in lesions from Lmax (maximum lesion count during treatment), which assesses the ability to clear subclinical and clinical lesions. METHODS Patients with 5-20 AK lesions on the full face or balding scalp from two 14-week, randomized, vehicle-controlled, double-blind studies of imiquimod 3.75% (daily for two 2-week treatment cycles separated by a 2-week treatment-free period) were eligible to enter a 12-month follow-up study if they had no AK lesions at Week 14. Lesion reduction from Lmax was calculated at 6 and 12 months during follow-up. RESULTS The 42 patients in this long-term study had a median of nine baseline lesions and a median Lmax of 22 lesions. At 6 and 12 months of follow-up, the median absolute reduction in AK lesions from Lmax with imiquimod 3.75% was 21 and 19, respectively. The median percentage reduction in lesions from Lmax to 6 and 12 months was 100% and 97.2%, respectively. CONCLUSIONS The ability of imiquimod 3.75% to eliminate clinical and subclinical lesions across an entire sun-exposed field translates into sustained long-term efficacy. Imiquimod 3.75% may therefore represent a first-choice treatment for patients with AK.