Imiquimod 5% cream for the treatment of actinic keratosis: Results from a phase III, randomized, double-blind, vehicle-controlled, clinical trial with histology

Background: Increasing evidence suggests imiquimod may be a safe therapeutic option for the treatment of actinic keratosis (AK). The diagnosis and assessment of most AK lesions is made clinically, without histologic confirmation. Objective: A phase III, randomized, double-blind, parallel group, vehicle-controlled study evaluated the efficacy of imiquimod 5% cream compared with vehicle in the treatment of AK lesions on the face and balding scalp including pretreatment and posttreatment biopsy specimens. Methods: A total of 286 patients at 18 centers in 6 European countries with histologically confirmed AK were randomized to either imiquimod 5% cream or vehicle cream. Study cream was applied once per day, 3 days per week, for 16 weeks. Clearance of AK lesions was clinically and histologically assessed at an 8-week posttreatment visit. Results: The complete clearance rate for the imiquimod group was 57.1% versus 2.2% for the vehicle group (P < .001). The partial clearance rate (greater than or equal to 75% reduction in baseline lesions) for the imiquimod group was 72.1% versus 4.3% for the vehicle group (P < .001). The most common side effects were erythema, scabbing/crusting, and erosions/ulceration. For the imiquimod group the incidence of severe erythema, scabbing/crusting, or erosions/ulceration was 30.6%, 29.9%, and 10.2%, respectively. Conclusion: Imiquimod 5% cream used 3 times per week for 16 weeks is an effective treatment for AK. Clinical clearance was established by both clinical observation and histologic analysis.