Imiquimod

Abstract

Imiquimod, available as a 5% cream, is a new topical treatment for adults with superficial basal cell carcinoma (BCC). The exact mechanism of action of imiquimod in superficial BCC is unknown. Imiquimod may act as a toll-like receptor-7 agonist, and is thought to exert its anti-tumor effect via modification of the immune response and stimulation of apoptosis in BCC cells. Topical imiquimod 5% cream effectively increased clinical and histologic clearance of single superficial BCC lesions compared with vehicle in patients enrolled in two large, well designed trials. Patients applied imiquimod five or seven times per week or vehicle for 6 weeks, and the composite clearance rates at 12 weeks post-treatment for the corresponding treatment groups were 75%, 73%, and 2%, respectively. In a trial investigating the long-term efficacy of imiquimod 5% cream following application five times per week for 6 weeks, a clinical clearance rate of 90% was reported at the initial 12-week post-treatment examination. The estimated rate of clinical clearance at the 1-year follow-up visit was 84%. Application site and local skin reactions were the most common adverse events reported by imiquimod recipients. The severity of erythema, erosion, and scabbing/crusting correlated positively with the composite and histologic response rates.