Povetacicept shows significant proteinuria reduction in IgA nephropathy trial

Interim results from the phase 3 RAINIER trial indicate that povetacicept, an investigational dual inhibitor of B-cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL), significantly reduces proteinuria in adults with IgA nephropathy (IgAN).

In the randomized, double-blind, placebo-controlled study, participants receiving 80 mg of povetacicept every four weeks achieved a 52.0% reduction in 24-hour urine protein-to-creatinine ratio (UPCR) at week 36, compared to a 4.3% reduction in the placebo group. Additionally, 42.2% of patients treated with povetacicept reached the KDIGO-aligned target of a UPCR below 0.5 g/g, whereas only 6.2% of the placebo group achieved this threshold.

The study also met secondary endpoints, including the lowering of galactose-deficient IgA1 (Gd-IgA1) levels and the resolution of hematuria in 85% of participants with baseline hematuria. Adverse event rates were reported to be similar between the treatment and placebo groups. Researchers presented these findings at the American Society of Nephrology Kidney Week 2026.