A phase II dose-ranging study of topical resiquimod to treat actinic keratosis

Background Resiquimod, a toll-like receptor 7 and 8 agonist, may be effective as a topical treatment of actinic keratosis (AK). Objective To evaluate the effect of resiquimod gel concentration on lesion clearance. Methods Patients with AK lesions on the face or balding scalp were randomly assigned to resiquimod 0.01%, 0.03%, 0.06% or 0.1% gel applied once daily three times a week for 4 weeks to a contiguous 25-cm(2) area with four to eight lesions. Patients with persistent lesions received a second course after an 8-week treatment-free interval. Complete and partial lesion clearance was assessed 8 weeks after treatment for each course. Results For the 132 patients randomized, overall complete clearance rates were 77.1% (27/35), 90.3% (28/31), 78.1% (25/32) and 85.3% (29/34) and complete clearance rates after course 1 only were 40.0%, 74.2%, 56.3% and 70.6%, respectively, for the resiquimod 0.01%, 0.03%, 0.06% and 0.1% groups. During course 1, respectively 0%, 13%, 31% and 38% of patients discontinued treatment for adverse events or local skin reactions, for the resiquimod 0.01%, 0.03%, 0.06% and 0.1% groups. Possibly or probably related nonapplication site adverse events of severe intensity, including influenza-like symptoms, were reported by 0%, 3%, 13% and 12% of patients, respectively, for the resiquimod 0.01%, 0.03%, 0.06% and 0.1% groups. Conclusions Efficacy in clearing AK lesions was similar between the resiquimod concentrations evaluated, but resiquimod 0.01% and 0.03% were better tolerated than the higher concentrations.