Ionis Pharmaceuticals Announces Positive Phase 3 Interim Results for Sefaxersen

What Happened
Ionis Pharmaceuticals (IONS) announced on September 23, 2026 that, together with partner Roche, it 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: sefaxersen produced statistically significant and clinically meaningful reductions in proteinuria versus placebo at 37 weeks, measured by 24‑hour urine protein‑to‑creatinine ratio (UPCR). The safety and tolerability profile was consistent with prior data and no new safety signals were identified. Ionis furnished a press release as Exhibit 99.1 to the Form 8‑K.

Key Details

• Study and timing: Phase 3 IMAgINATION study; prespecified interim analysis at 37 weeks (announced Sept 23, 2026).
• Primary endpoint: Statistically significant and clinically meaningful reduction in proteinuria (24‑hour UPCR) vs placebo.
• Safety: No new safety signals; tolerability consistent with earlier reports.
• Program and commercialization: Sefaxersen is a once‑monthly subcutaneous injection; Roche licensed sefaxersen from Ionis. Ionis previously received an upfront payment, license fee and development milestone payments and may receive future regulatory/sales milestones and tiered royalties.
• Next steps: The study remains blinded and will continue to assess kidney function over two years (eGFR at week 105). Interim data will be presented at an upcoming medical congress and shared with regulators.

Why It Matters
For investors, the positive interim readout supports clinical progress for sefaxersen in a high‑unmet‑need kidney disease (IgAN), where reducing proteinuria is strongly linked to preserving long‑term kidney function. Meeting the primary endpoint and a clean interim safety profile may de‑risk the program and bolster the candidate’s regulatory and commercial prospects under the Roche collaboration. However, the study will continue to final endpoints (eGFR at week 105), and Ionis’ statements are forward‑looking and subject to development, regulatory and commercial risks described in its SEC filings.