Efficacy of imiquimod 3.75% from Lmax according to the number of actinic keratosis lesions

Background Imiquimod 3.75% reduces 92.2% of all actinic keratosis (AK) lesions, assumed to include both subclinical and clinical lesions, across a large sun-exposed field such as the full face or balding scalp. Objective To evaluate the efficacy of imiquimod 3.75% using the reduction in lesions from Lmax (the maximum lesion count during treatment) in subgroups of patients with low and high AK lesion counts. Methods Patients from two 14-week, placebo-controlled, double-blind studies were subgrouped according to whether they had <= 10 or > 10 AK lesions at baseline. Treatment was applied to the full face or balding scalp during two 2-week treatment cycles separated by a 2-week treatment-free interval. Results Overall, 167 patients had <= 10 lesions and 152 patients had > 10 AK lesions at baseline. With imiquimod 3.75%, the median percentage reduction in AK lesions from Lmax to end of study was similar in patients with <= 10 and > 10 baseline lesions (91.5% and 93.0% respectively). The median absolute reduction in AK lesions from Lmax to end of study was 24.0 for patients with > 10 baseline lesions and 10.0 for those with <= 10 baseline lesions. The median percentage and absolute reductions in lesions from Lmax were significantly greater with imiquimod 3.75% vs. placebo (P < 0.0001). Conclusions Imiquimod 3.75% is effective regardless of disease severity as shown in this study by the reduction of over 90% of lesions from Lmax in patients with low or high AK lesion counts.