The progression of AK to invasive SCC has been reported to be up to 16% per year. Although some AKs may regress spontaneously, there are no clinical criteria to predict which AKs will evolve into invasive SCC.
Therefore, treatment and monitoring over time is warranted. Del Rosso et al evaluated safety of multiple 16-week courses of imiquimod applied to large areas (>25cm2) of skin with actinic keratoses.
Participants included adults with ≥4 actinic keratoses on the head, torso, and/or extremities.
For 525 subjects, the mean baseline lesion count was 45.5±2.4. Overall reduction in target lesion count was 80% (p<0.0001, 95% CI 77.2–83.3%), with overall complete clearance rate of 36% and partial clearance rate (≥75% reduction) of 68%.
Subjects were treated with up to three treatment courses of 16 weeks, for a total of up to 48 weeks of treatment over 18 months. In addition, the dosing and the treatment area was much greater than for the approved dosing for AK, with up to 6 x 250mg cream applied twice weekly in this study, and a baseline median treated area of 285cm2. With this extensive exposure, treatment was generally well tolerated. There were no serious AEs attributed to study drug and only 4% of the subjects discontinued treatment for AEs attributed to study drug or for LSRs.
In summary, up to 48 weeks of twice per week dosing with imiquimod 5% cream, involving up to 250mg cream per dose applied to large areas of skin with AK involvement, including the head, torso, and/or extremities, was considered well tolerated overall. No new safety findings were observed over the 18 months of the study. There was evidence of clinical benefit with respect to overall percent lesion reduction. Complete and partial clearance of AKs was achieved for a meaningful proportion of subjects after each treatment course in a population with extensive AKs.
Multiple 16-week courses of imiquimod to treat actinic keratoses were well tolerated and significantly decreased lesions in subjects with extensive actinic keratoses.
Del Rosso JQ, Sofen H, Leshin B, et al. Safety and Efficacy of Multiple 16-week Courses of Topical Imiquimod for the Treatment of Large Areas of Skin Involved with Actinic Keratoses. J Clin Aesthet Dermatol. 2009;2:20-8. PMID: 20729935.