Scholar Rock announced 8 May 2026 that the U.S. Food and Drug Administration has accepted its Biologics License Application (BLA) for apitegromab. The Prescription Drug User Fee Act (PDUFA) action date is 30 September 2026, with full FDA review expected to take up to six months.

Why this matters for the SMA community

Apitegromab is a humanized IgG4 monoclonal antibody that selectively inhibits myostatin (GDF8) — a negative regulator of muscle mass. It is the first muscle-targeted SMA therapy to reach late-stage FDA review, complementary to the existing SMN-restoring drugs (nusinersen / Spinraza, risdiplam / Evrysdi, onasemnogene abeparvovec / Zolgensma). The Phase 3 SAPPHIRE trial reported positive readout in 2025 showing improvement in HFMSE (Hammersmith Functional Motor Scale Expanded) when added on top of standard SMN-restoring background therapy.

Background

Earlier FDA concerns about a third-party manufacturing facility — not about apitegromab itself — led to a previous resubmission. Scholar Rock has since added a second U.S.-based manufacturing facility to support reliable supply if the treatment is approved.

Pipeline relevance

An approval would validate the combination-therapy direction (SMN-restorer + muscle-target) as the new clinical standard for SMA. It also opens the door for complementary muscle-axis approaches such as cytoskeletal-pathway targeting (ROCK / LIMK / cofilin axis), HDAC6 inhibition, and other anti-atrophy mechanisms now being explored in research programs worldwide.

Source: Scholar Rock public statement 8 May 2026; SMA Europe May 2026 newsletter.