Imiquimod applied topically: A novel immune response modifier.

Imiquimod (S-26308, R-837) (1-(2-methylpropyl)-1H-imidazo[4,5-c]quinolin-4 amine), and immune response modifier, was approved as a 5% cream (Aldara, 3M Pharmaceuticals) by the US FDA in February 1997, for the treatment of genital and perianal warts. Drug activity results primarily from induction of interferon alpha (IFN-alpha) and other cytokines in the skin, which stimulate several other aspects of the innate immune response. Imiquimod also stimulates acquired immunity, in particular the cellular arm, which is important for control of viral infections and tumors. It is expected to be effective where exogenous IFN-alpha has shown utility, and where enhancement of cell-mediated immunity is needed. Recently presented Phase II clinical studies demonstrated efficacy in treating UV induced skin lesions, basal cell carcinoma, and actinic keratosis. Case studies have reported benefit when treating molluscum and in prevention of keloids after surgery.