Sefaxersen cut proteinuria significantly versus placebo at 37 weeks in the ongoing Phase 3 IMAgINATION study, Roche announced Tuesday, meeting the trial’s primary endpoint on a prespecified interim look. The measurement was 24-hour urine protein-to-creatinine ratio, the same surrogate that regulators have already accepted for accelerated approvals in IgAN, which means this readout carries direct regulatory weight, not just biological interest.
The drug’s mechanism sets it apart from the complement inhibitors already on the market for IgAN. Sefaxersen is an antisense oligonucleotide that silences complement factor B at the mRNA level, suppressing the alternative complement pathway upstream of where most approved agents intervene. That pathway is central to the glomerular damage that drives proteinuria in IgAN, so the logic is mechanistically tight. Whether upstream silencing translates into deeper or more durable proteinuria suppression than existing options is a question the full IMAgINATION dataset will need to answer.
The competitive context matters here. Iptacopan (Fabhalta) received FDA accelerated approval for IgAN in August 2024 on the basis of a 44% proteinuria reduction, and the approval field has continued to widen since. Roche did not disclose the magnitude of sefaxersen’s reduction in today’s interim announcement, which makes cross-trial comparisons impossible at this stage. That number, when it arrives with the full interim data presentation, is the figure that will determine whether sefaxersen can compete on effect size in a market where the proteinuria bar is already defined by approved drugs.
IMAgINATION is ongoing, so the interim read is not the final word on safety or long-term kidney function outcomes. The study continues to its primary completion, and the eventual eGFR trajectory data will matter as much as the proteinuria result for any label claim that goes beyond the accelerated pathway. Watch for the full interim dataset presentation, where the absolute UPCR reduction figure will tell analysts and clinicians whether sefaxersen’s alternative pathway approach offers anything meaningfully different from what IgAN patients can already access.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
