Resiquimod: a new topical immune-response modifier for the treatment of actinic keratosis.

Resiquimod is a Toll-like receptor (TLR)-7 and TLR-8 agonist that, like imiquimod, belongs to the class of imidazoquinolines, small organic molecules with potent antiviral and anticancer activity. Resiquimod activates myeloid and plasmacytoid dendritic cells while also promoting release of cytokines as interleukin-6, tumor necrosis factor-α and interferon-γ more effectively than imiquimod. Given these immunologic effects, resiquimod is emerging as a new topical pharmacotherapy for actinic keratosis (AK). In the pivotal trial by Stockfleth et al. complete clinical clearance in all the resiquimod-treated arms was more significant than placebo varying from 56% to 74%. Partial clinical clearance, or disappearance of >75% of AKs, was also significantly higher in the resiquimod arms varying from 75% to 87%. Overall, resiquimod is a new molecule that remains a promising therapy for AK, although additional studies are needed to further evaluate its efficacy.