Otsuka Pharmaceutical announced that FDA granted accelerated approval of Voyxact (sibeprenlimab-szsi) as a treatment for the reduction of proteinuria in adults with primary immunoglobulin A nephropathy (IgAN) on November 26th, 2025. According to a company press release, sibeprenlimab-szsi is a self-administered, subcutaneous injection designed to block A-PRoliferation-Inducing-Ligand. This is intended to reduce levels of serum-galactose-deficient IgA1, a molecule implicated in the pathogenesis of IgAN.

FDA approval was based on an interim analysis of the Phase III VISIONARY clinical trial. According to the release, the treatment resulted in a 50% reduction in proteinuria at nine months of treatment, compared to 2% in patients given placebo. (The placebo-adjusted treatment reduction was assessed at 51%.) Proteinuria reduction is considered a surrogate marker for delaying progression to kidney failure in IgAN, and is used as a surrogate endpoint in IgAN clinical trials.

“The availability of [sibeprenlimab-szsi] represents a novel targeted approach to help manage this complex disease for patients living with IgAN,” said John Kraus, M.D., Ph.D., executive vice president and chief medical officer, Otsuka, in the release. “With its targeted mechanism, strong efficacy, safety profile, and once-every-four-weeks dosing, [sibeprenlimab-szsi] offers a new option for IgAN patients. We recognize the urgent need for new treatment options for IgAN and are thankful for the patients and healthcare professionals who continue to participate in our clinical trial program.”

According to the release, because proteinuria reduction is a surrogate endpoint for delayed progression to kidney failure, it has not yet been established if sibeprenlimab-szsi slows kidney function decline. Data concerning whether the treatment slows disease progression as measured by estimated glomerular filtration rate decline at 24 months is expected to be available in early 2026, which may support a full approval.