Background: This Phase 2, open-label study evaluated the safety, efficacy, systemic exposure, and impact on quality of life (QoL) with treatment using VP-102, a drug-device combination containing cantharidin (0.7% w/v) in subjects with molluscum contagiosum (MC). Study Design: Pediatric subjects with MC (2-15 years of age) were eligible to enroll in this 12-week study. MC lesions were treated topically with VP-102 every 21 days until clearance (maximum of 4 treatments). Adverse events (AEs) and QoL outcomes (using the Children's Quality of Life Index, CDLQI) were documented at each visit. Rate of complete clearance and the percent reduction in lesions were measured at each visit on days 21, 42, 63, and 84 (end of study [EOS] visit). A group of 17 subjects with at least 21 MC lesions was evaluated for systemic cantharidin exposure via plasma samples obtained before the first application of VP-102, and at 2 hours, 6 hours, and 24 hours post-application. Results: A total of 33 subjects enrolled in the study (n=17 systemic exposure group, n=16 standard group). There were an equal number of male and female subjects. Subject mean (SD, range) age was 6.7 (3.3, 2-15) years, with a mean lesion count of 30 (26.1, 3-113). Complete lesion clearance was achieved in 48.5% of subjects, with a 90.4% reduction in lesions from baseline to the EOS visit. Mean CDLQI score decreased from 2.6 at baseline to 0.38 at the EOS visit. AEs were mild to moderate in severity and expected due to the pharmacodynamic action of cantharidin. There were no serious treatment-related adverse events and no study discontinuations due to treatment. In the systemic exposure group plasma cantharidin levels were below the lower limit of quantitation (LLOQ, 2.5 ng/ mL) in 65 of 66 samples. Conclusions: VP-102 treatment resulted in a reduction in lesion counts and improved QoL. Treated subjects had a 48.5% rate of complete clearance of molluscum lesions. Negligible systemic cantharidin exposure was observed in the systemic exposure group. This data demonstrates safety and efficacy of treatment with VP-102 in MC; a widespread viral infection that does not have any current FDA-approved treatments. Significant Finding: Treatment of subjects with MC using VP-102 resulted in negligible systemic cantharidin exposure, as well as a reduction in lesion counts, improved QoL, and a demonstrated efficacy in clearance of new and baseline MC lesions. Meaning: Results of this Phase 2 study demonstrate efficacy and safety outcomes in using VP-102 in MC subjects, and large randomized clinical trials are warranted to compare topical VP-102 with a vehicle control in order to fully evaluate the use of the medication. ClinicalTrials.gov identifier: NCT03186378

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