SRK-439
SRK-439, subcutaneous selective myostatin inhibitor
Scholar Rock's follow-on to apitegromab, engineered for self-injection alongside GLP-1 drugs; Phase 1 readout expected in the second half of 2026.
Overview
SRK-439 targets the same pro/latent myostatin as apitegromab but is formulated for subcutaneous use in obesity. Non-human primate data showed lean-mass increases at every dose, and mouse data suggested it blunts fat regain after stopping a GLP-1 drug. A Phase 1 study in healthy volunteers is under way.
Mechanism of action
Antibody inhibition of pro/latent myostatin activation.
Key studies & citations
- Review2026
Scholar Rock first quarter 2026 results and pipeline update
Phase 1 topline for SRK-439 guided to H2 2026.
Scholar Rock press release - Animal2025
New SRK-439 preclinical data
Lean-mass gains in primates; reduced fat rebound after GLP-1 withdrawal in mice.
Scholar Rock press release
Frequently asked questions
How is SRK-439 different from apitegromab?
Same target, but SRK-439 is built for subcutaneous self-injection and the obesity setting rather than intravenous infusion in spinal muscular atrophy.