Viatris Inc. (Nasdaq: VTRS) reported positive top-line results from a Phase III bridging study of VR-205 (targeted-release budesonide) in Japanese adults with primary IgA nephropathy (IgAN), clearing the path for a New Drug Application submission in Japan by the end of 2026. The result matters because Japan carries the highest IgAN incidence globally — 39 to 45 cases per million population per year — yet no IgAN-specific targeted therapy has received approval from the Pharmaceuticals and Medical Devices Agency. A successful NDA would make VR-205 the first such product approved in Japan, opening a market where IgAN is classified as a designated intractable disease and where chronic glomerulonephritis accounts for nearly a quarter of the country's more than 340,000 dialysis patients.
The trial (VR-205A-01-CAZ-3001) enrolled 39 Japanese adults and treated them with 16 mg VR-205 daily for nine months, followed by a three-month tapering follow-up. It is an open-label, single-arm bridging study — a design the PMDA has accepted for drugs with established global datasets, allowing small-scale Japanese confirmation rather than a full replicate trial. The primary endpoint, geometric mean urine protein-to-creatinine ratio (UPCR) reduction at nine months versus baseline, was met with a 33.75% reduction (95% CI: −45.27 to −19.80; p-value reported as statistically significant). Secondary endpoints including UPCR reductions at six and twelve months, eGFR improvement, serum creatinine, and urine albumin-to-creatinine ratio were also statistically significant. Notably, no participant progressed to dialysis, kidney transplant, or severe renal impairment during the study period.
Competitive context
The result validates the 2022 exclusive license agreement between Sweden-based Calliditas Therapeutics AB and Viatris Pharmaceuticals Japan. The same molecule is approved as Calliditas's Tarpeyo (budesonide delayed-release capsules) in the US — where it received full FDA approval in December 2023 — and as Kinpeygo in Europe. The Japan-specific bridging study design mirrors the approach used by Renalys Pharma (now a Chugai Pharmaceutical subsidiary) for Travere Therapeutics' Filspari (sparsentan), which reported a 58.54% UPCR reduction at 36 weeks in its own Japanese Phase III study and plans an NDA submission in 2026. Cross-trial comparisons are limited by differences in study design, patient populations, and endpoints, but both programs are on roughly parallel regulatory timelines in Japan.