Efficacy of imiquimod 5% cream in the treatment of superficial basal cell carcinoma

BACKGROUND: Imiquimod is an immune response modifier that is a Toll-like Receptor 7 agonist1, 2 that induces interferon and other cytokines. OBJECTIVE: To evaluate the efficacy and safety of imiquimod 5% cream at 2 dosing regimens compared to vehicle for the treatment of superficial basal cell carcinoma (sBCC). METHODS: Two randomized, double-blind, vehicle-controlled, phase 3 clinical studies with identical design enrolled subjects with 1 histologically-confirmed sBCC tumor at least 0.5cm2 and a maximum diameter of 2.0 cm. Subjects were randomized to imiquimod or vehicle for dosing once daily 5 or 7 times/week for 6 weeks. The tumor site was clinically examined for sBCC 12 weeks posttreatment followed by excision for histological evaluation. Safety assessments included clinical lab tests and evaluation of adverse events (AEs) and local skin reactions. RESULTS (POOLED DATA): A total of 724 subjects were randomized. The pooled composite response rates (based on both clinical and histological assessments) for the ITT group were 75% and 73% for the 5 and 7×/week dosing groups, respectively, versus 2% for both vehicle groups. Histological response rates for the ITT group were 82% and 79% for the 5 and 7×/week dosing groups, respectively, versus 3% for both vehicle groups. Increasing severity of erythema, erosion, and scabbing/crusting was associated with higher composite and histological clearance rates for both imiquimod dosing regimens. This trend was statistically significant (p < 0.05). No significant subgroup or treatment-by-subgroup effects were found for demographic characteristics of sex, age (<65 yrs vs. ≥65 yrs), Fitzpatrick Skin Type, and geographic area (North, Southwest and Southeast) for either endpoint. There was no significant difference between the 2 imiquimod dosing groups for any of these subgroups based on the type III analyses performed. CONCLUSIONS: There was no significant difference in composite or histological response rates between the 2 imiquimod dosing regimens. Treatment effects are consistent in the demographic subgroups of sex, age, skin type and geographic area.1Hemmi H. Kaisho T. Takeuchi O. et al.Small antiviral compounds activate immune cells via the TLR7 MyD88-dependent signaling pathway.Nat. Imunol. 2002; 3: 196-200Crossref PubMed Scopus (2081) Google Scholar, 2Gibson S. Lind J. Riter T. et al.Plasmacytoid dendritic cells produce cytokines and mature in response to the TLR7 agonists, imiquimod and resiquimod.Cellular Immunol. 2002; 218: 74-86Crossref PubMed Scopus (343) Google Scholar