Otsuka adds Phase 3 detail behind Voyxact in IgA nephropathy

Otsuka has reported additional Phase 3 VISIONARY data for Voyxact (sibeprenlimab-szsi) in adults with primary IgA nephropathy, adding confirmatory detail to the proteinuria benefit that supported the drug’s U.S. accelerated approval in November 2025. In the prespecified interim analysis, published in The New England Journal of Medicine, sibeprenlimab cut 24-hour urine protein-to-creatinine ratio by 50.2% at nine months, versus a 2.1% increase with placebo, for a 51.2% placebo-adjusted reduction. The randomized, double-blind trial enrolled 510 patients overall, with the interim analysis covering the first 320 participants who reached the nine-month assessment. Safety appeared broadly similar to placebo, with no deaths reported in the treatment period. Additional data presented at ISN WCN’26 also pointed to an effect on microscopic hematuria, an exploratory endpoint: 82.5% of treated patients versus 52.6% on placebo achieved negative microscopic hematuria (0–5/HPF) by 48 weeks, with a median time to that threshold of 9 weeks versus 24 weeks. (pubmed.ncbi.nlm.nih.gov)

Why it matters: For veterinary professionals tracking translational kidney research, Voyxact is another sign that targeted immunology is reshaping glomerular disease treatment. The drug blocks APRIL, a pathway tied to production of pathogenic galactose-deficient IgA1, and the trial also showed marked reductions in APRIL and Gd-IgA1 biomarkers. The newer hematuria data add another potentially useful disease-activity signal, though exploratory findings should be interpreted cautiously. FDA has made clear that Voyxact’s current approval is based on proteinuria reduction, not yet on proven long-term slowing of kidney function decline, so the field is still waiting for the harder outcome that would support full approval. (pubmed.ncbi.nlm.nih.gov)

What to watch: The key next milestone is still the VISIONARY trial’s 24-month eGFR slope readout, which is intended to test whether Voyxact preserves kidney function over the full treatment period and which FDA has said will be needed to verify clinical benefit and could support traditional approval. (fda.gov)