SOUTH SAN FRANCISCO, Calif. — September 22, 2026
Genentech reported positive prespecified interim results from the ongoing Phase 3 IMAgINATION study of investigational sefaxersen in adults with primary IgA nephropathy (IgAN). The study met its primary endpoint, with sefaxersen demonstrating statistically significant and clinically meaningful reductions in proteinuria versus placebo at Week 37, measured by the 24-hour urine protein-to-creatinine ratio (UPCR). Genentech said the safety and tolerability profile remained consistent with previously reported data, with no new safety signals identified.
Sefaxersen Targets Complement Factor B in IgAN
Sefaxersen is an investigational liver-directed antisense oligonucleotide designed to inhibit production of complement factor B, a component of the alternative complement pathway implicated in IgAN-related kidney damage. Genentech said factor B levels are elevated in people with IgAN and that reducing factor B production is intended to provide sustained control of the alternative complement pathway. Sefaxersen is being developed as a once-monthly subcutaneous injection designed for self-administration. Earlier Phase 1 and Phase 2 studies showed reductions in proteinuria and plasma complement factor B, while the treatment was generally well tolerated..
IMAgINATION Continues to Evaluate Kidney Function
The Phase 3 IMAgINATION study enrolled 459 patients at high risk of IgAN progression, with participants randomized 1:1 to receive sefaxersen or placebo for 105 weeks. Although the Week 37 UPCR endpoint was met, the study remains blinded to evaluate longer-term kidney function, with the key assessment based on change in estimated glomerular filtration rate (eGFR) at Week 105. The company said the interim findings will be presented at an upcoming medical congress and shared with health authorities. The Week 37 proteinuria results therefore provide an interim clinical readout, while the longer-term effect on kidney function remains under evaluation.
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Genentech Advances Targeted IgAN Treatment Approach
IgA nephropathy is a chronic and progressive autoimmune kidney disease that can lead to kidney failure, with Genentech citing estimates that up to 50% of patients may progress to end-stage kidney disease within 20 years of diagnosis. Sefaxersen is being developed to address an underlying complement-mediated pathway rather than focusing solely on downstream consequences such as proteinuria and blood pressure. Roche, Genentech’s parent company, licensed sefaxersen from Ionis Pharmaceuticals for complement-mediated diseases. The ongoing IMAgINATION study is expected to provide additional evidence on whether the observed reduction in proteinuria translates into preservation of kidney function over the longer term.
Source :Genentech, press release
