Phase 2 Safety and Efficacy of VP-102, a Drug-Device Combination Product Containing Cantharidin (0.7% w/v), for the Treatment of External Genital Warts (CARE-1). Guenthner S, McFalda W, Tate M, et al. Winter Clinical Dermatology Symposium 2021
Background: External genital warts (EGW) are caused by the human papilloma virus, which is spread through direct skin-to-skin contact. Approximately 1% of people in the US have genital warts. Cantharidin has been used to treat EGW for decades, however there are no FDA-approved cantharidin products and no reliable or controlled source of cantharidin available.
Objective: VP-102 is a drug-device combination product that contains cantharidin (0.7% w/v). The primary objective of this Phase 2 study was to determine the optimal exposure duration for treatment, as well as the safety and efficacy of VP-102 in the treatment of EGW compared to vehicle.
Methods: This Phase 2, randomized, double-blind, vehicle-controlled trial included two parts (A and B). Participants in study Part A (dose regimen finding) were randomized in a 5:1 ratio to receive either a 2-hour, 6-hour, or 24-hour exposure duration of VP-102 or vehicle. Participants in Part B received VP-102 or vehicle in a 3:2 ratio with a 6- or 24-hour exposure duration. Study drug application occurred to any existing EGW every 21±4 days until complete clearance, or a maximum of 4 applications. Study drug was applied and covered with 3M® Dermablend surgical tape and removed at the designated exposure group time. An end of treatment (EOT) visit occurred at Day 84. Efficacy was measured by the percentage of subjects with complete clearance of all baseline and new treatable EGW at EOT. Safety was measured by incidence of adverse events (AEs) including local skin reactions (LSRs). Data for Part A and B were pooled for each individual treatment and exposure duration for safety and efficacy outcomes.
Results: Subjects presented with a mean wart count of 8.2 with a range of 2 to 30 EGW at baseline. Approximately 50% of subjects had EGW for one year or longer; with approximately 23% of subjects having EGW for more than five years. Pooled results from the 6- or 24-hour VP-102 treatment exposure groups showed 36.7% and 33.3% of subjects achieved complete clearance of all treatable EGW at Day 84 compared to 4.5% (P<0.05) and 0% (P<0.01) of subjects treated with vehicle. AEs experienced by the VP-102 treated subjects were consistent with the pharmacodynamic action of cantharidin as a vesicant. These side effects were primarily mild-to-moderate. The most common side effects included application site vesicles, pain and erythema. No subjects discontinued from the study due to adverse events and there were no serious adverse events reported that were deemed related to treatment by the investigator.
Conclusions: Treatment of EGW with VP-102 resulted in statistically significantly higher complete clearance of all EGW at the end of study visit compared to vehicle. VP-102 was well-tolerated and safety outcomes were consistent with the pharmacokinetic action of cantharidin as a vesicant.
