SRK-015 / Apitegromab (Scholar Rock)
SRK-015 / Apitegromab (Scholar Rock)
Read or latest blog on access to Apitegromab in the UK here >
Page last updated: 7th October 2026
OPAL Trial
A clinical trial is recruiting young children with spinal muscular atrophy (SMA) to investigate apitegromab in children under two years old who have had one of the three currently available treatments for SMA.
The OPAL study is a Phase 2 clinical trial sponsored by Scholar Rock. It plans to include around 52 children with 5q SMA across several countries, including the UK.
Read more here
SAPPHIRE Trial
Informed by the results of the TOPAZ trial (see below), SAPPHIRE was a randomised, double-blind, placebo-controlled Phase 3 study that aimed to assess the safety and efficacy of apitegromab in conjunction with SPINRAZA® (nusinersen) or EVRYSDI® (risdiplam). Trial participants were non-ambulatory individuals aged 2-21 years living with Type 2 or Type 3 SMA. The SAPPHIRE trial was completed in December 2024 and showed that apitegromab treatment caused moderate improvements in motor function.
TOPAZ Trial
This Phase 2 study by Scholar Rock was a proof-of-concept trial designed to assess the safety and efficacy of apitegromab in conjunction with SPINRAZA® (nusinersen). Trial participants were non-ambulatory (unable to walk independently) individuals aged 2-21 years living with SMA Type 2 or Type 3. The extension phase of TOPAZ was completed in February 2024 and concluded that apitegromab led to some improvements in motor function, that was variable between individuals.
ONYX Trial
This is an ongoing open-label Phase 3 study by Scholar Rock designed to assess the long-term safety and efficacy of apitegromab in people living with Type 2 and Type 3 SMA who completed the TOPAZ or SAPPHIRE trial (see above). ONYX is due to be completed in 2029.
Page last updated: 5th November 2024
2024
7th October: Apitegromab successfully meets primary endpoint in Phase 3 of the SAPPHIRE study.
2023
27th October: Scholar Rock presented the latest data from their Phase 2 TOPAZ trial of apitegromab at the 3rd International Scientific Congress on SMA in Barcelona, Spain (22nd October).
20th September: Scholar Rock announced the opening of the initial European clinical trial sites for the Phase 3 SAPPHIRE study in Spain, with additional sites to be announced.
30th June: Scholar Rock announced the latest data from their TOPAZ trial.
23rd June: Phase 2 trial (TOPAZ) extension data, presented at the recent Cure SMA Research & Clinical Care Meeting.
2021
2nd December: Scholar Rock announce design of Phase 3 clinical trial SAPPHIRE
7th July: Scholar Rock received Fast Track Designation in the US from the FDA for Apitegromab for the treatment of SMA.
8th April: Scholar Rock announces results from TOPAZ Phase 2 trial in SMA Types 2 and 3.
2020
28th October: Scholar Rock announces encouraging interim data from the TOPAZ Phase 2 trial
13th May: Scholar Rock reports delays in TOPAZ interim trial results due to Covid-19
2019
25th November: Scholar Rock presents the preliminary pharmacokinetic and pharmacodynamic analysis of the TOPAZ Phase 2 trial
18th March: Positive interim results from Phase 1 TOPAZ trial announced by Scholar Rock
2018
4th December: European Medicines Agency (EMA) gives SRK-015 Orphan Drug Designation for SMA status.
Scholar Rock also recently published some pre-clinical data on the effects of an early-generation variant of SRK-015, called SRK-015P, in SMA mouse models which has a very similar mode of action and is likely to have a comparable impact on muscles as SRK-015. The publication in Human Molecular Genetics, showed that co-administration of SRK-015 with a drug that increases SMN levels called SMN-C1 (click here for more information) provided greater benefit than SMN-C1 treatment on its own. The combination treatment resulted in increased size and strength of muscles, as well as improvements in bone deficiencies that have previously been reported in SMA mice.
Scholar Rock pre-clinical SRK-015 publication >
8th June: Dosing of the first cohort completed in TOPAZ Phase I trial to assess the safety, tolerability, pharmacokinetics, and pharmacodynamics of intravenous injections of SRK-015 in healthy adult volunteers.
3rd May: The US Food and Drug Administration (FDA) granted Orphan Drug Designation to SRK-015 for the treatment of SMA.