Torii Pharmaceutical and Verrica Pharmaceuticals have dosed the first Japanese patient in a global Phase 3 trial of TO‑208 for common warts, advancing their cantharidin‑based therapy toward potential regulatory approval in Japan.
Written By: Fariha Sameen, PharmD
Reviewed By: Pharmacally Editorial Team
Torii Pharmaceutical and Verrica Pharmaceuticals have enrolled and dosed the first patient in Japan in a global Phase 3 trial of TO-208 for common warts, advancing a long-standing collaboration that could support regulatory approval of the therapy in Japan.
TO-208, marketed as YCANTH® for molluscum contagiosum in the United States and Japan, is being evaluated as a potential treatment for common warts. The Japanese enrollment milestone expands the ongoing global development program and marks an important step toward bringing a new treatment option to patients with this common viral skin disease.
Clinical Context
Common warts (verruca vulgaris) are benign but persistent lesions caused by human papillomavirus (HPV). They frequently affect the hands and feet, creating discomfort, cosmetic concerns, and reduced quality of life. Current treatments often produce variable outcomes, highlighting the need for additional therapeutic options.
TO-208 is a cantharidin-based topical therapy. Cantharidin, a vesicant agent long used in dermatology, disrupts desmosomal adhesion within the epidermis, triggering intraepidermal blister formation and subsequent detachment of HPV-infected tissue. Removal of infected tissue is believed to contribute to lesion clearance and therapeutic benefit.
The therapy is already marketed as YCANTH® for molluscum contagiosum, providing a regulatory and commercial foundation for potential label expansion into common warts.
Phase 3 Trial Design
The global Phase 3 study (jRCT2031250703) is a randomized, double-blind, placebo-controlled trial enrolling pediatric and adult patients aged two years and older with common warts.
Participants receive TO-208 or placebo once every 21 days for up to four treatment applications. The study is evaluating the efficacy and safety of TO-208 in this patient population and is expected to generate pivotal data to support future regulatory submissions.
Japan’s participation carries particular importance because local clinical data are often required by the Pharmaceuticals and Medical Devices Agency (PMDA) to support approval decisions. Enrollment of Japanese patients therefore strengthens the overall development package and regulatory pathway.
Partnership and Regulatory Trajectory
Torii and Verrica established their collaboration in March 2021, granting Torii exclusive rights to develop and commercialize Verrica’s VP-102 platform in Japan for molluscum contagiosum and common warts.
The partnership has already achieved a significant regulatory milestone. YCANTH® received U.S. Food and Drug Administration approval in July 2023 for the treatment of molluscum contagiosum in adults and pediatric patients aged two years and older, followed by its commercial launch in August 2023.
In Japan, Torii obtained manufacturing and marketing approval for YCANTH® in September 2025 and launched the product in February 2026. Building on that regulatory and commercial experience, the companies are now targeting common warts, a substantially larger market opportunity than molluscum contagiosum.
Development Momentum
The wart program continues to gain momentum globally. Verrica initiated Phase 3 studies in the United States in December 2025 and reported in May 2026 that enrollment in the first study had surpassed 50% of its target.
Enrollment of the first Japanese patient expands the global Phase 3 program into a key regulatory market. Positive trial results could support a marketing application in Japan and broaden the commercial reach of the YCANTH® franchise beyond molluscum contagiosum into the larger common wart treatment market.
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About the Writer
Fariha Sameen, PharmD (LinkedIn), is a clinical pharmacy professional with hands-on experience in patient counselling, medication review, therapeutic monitoring, and clinical documentation across multiple departments. She has experience identifying and assessing drug-related problems and supporting medication safety practices. Her interests include pharmacovigilance, ADR reporting, clinical research, and medical writing focused on clear, evidence-based communication.