Last updated: 11th August 2025

2025: Apitegromab successfully meets primary endpoint in Phase 3 SAPPHIRE study.

Apitegromab successfully meets primary endpoint in Phase 3 SAPPHIRE study.
The SAPPHIRE study included 188 participants aged 2-21 years living with Type 2 or Type 3 SMA and who were unable to walk. Enrolment for the SAPPHIRE trial was completed in September 2023.

Scholar Rock announced in early October 2024 that this trial of apitegromab demonstrated an overall statistically significant and clinically meaningful improvement in people living with SMA. Additional details were provided in a presentation at Cure SMA’s 2025 Annual SMA Conference.

Key findings include:

• In participants aged 2-12 years, 30.4% of people treated with apitegromab saw a motor function improvement of more than 3 points from baseline, compared to 12.5% on a placebo. This was assessed using the Hammersmith Functional Motor Scale – Expanded (HFMSE).
• Early improvements were seen within 8 weeks, with benefits lasting through a year.
• Motor function improvements were also observed in apitegromab-treated patients aged 13-21 years.
• The drug showed a favourable safety profile, consistent with earlier trials (e.g., Phase 2 TOPAZ).

Following trial completion, 98 percent of SAPPHIRE patients (185/188) enrolled in the ongoing ONYX open-label expansion study.

The U.S. Food and Drug Administration (FDA) has granted Fast Track, Orphan Drug and Rare Pediatric Disease designations to apitegromab for the treatment of SMA. The European Medicines Agency (EMA) has also granted Priority Medicines (PRIME) and Orphan Medicinal Product designations to apitegromab.

The trial confirmed that apitegromab improves motor function in both children (2-12) and young adults (13-21) when combined with existing SMA treatments.

• Scholar Rock SAPPHIRE Community Statement Oct 2024 >

2023

19th September: Scholar Rock announced the completion of patient enrolment for the SAPPHIRE Trial.

• Read the community update >
• Read the press release >

25th January (updated Sept 2023): Trial sites announced for the UK:

2022

20th September: Scholar announced the opening of the initial European clinical trial sites for the phase 3 SAPPHIRE study in Spain, with additional sites to be announced.

Read the community update >

2021

2nd December: Scholar Rock announced the design of this Phase 3 trial.

Read the community update >