Clinical Trials Pipeline & In-Development

Garetosmab

also known as: REGN2477

⚠ Monoclonal antibody — not a classical peptide. A Regeneron anti-activin-A fully human IgG (~150 kDa). Primary development target is fibrodysplasia ossificans progressiva (LUMINA-1 Phase 2); the activin-A mechanism overlaps bimagrumab biology, and the antibody is of cross-reference interest in the muscle-sparing-adjunct discussion.

A fully human monoclonal antibody developed by Regeneron that neutralizes activin A, in Phase 3 development for the ultra-rare genetic disorder fibrodysplasia ossificans progressiva following positive Phase 2 LUMINA-1 data; cross-referenced in the muscle-sparing-adjunct category because its activin-pathway mechanism overlaps bimagrumab's, though the clinical program is directed at FOP rather than obesity.

Mechanism of action

Binds and neutralizes activin A, a TGF-β superfamily ligand that signals through ActRIIA. In FOP, activin A is a pathological driver of heterotopic ossification via the mutant ACVR1 receptor. Blocking activin A removes the aberrant osteogenic signal. The pathway overlap with bimagrumab (which blocks ActRII receptors) is indirect but pharmacologically related.

Primary uses

  • Fibrodysplasia ossificans progressiva (Phase 3)

Typical dosing

not established mg/kg monthly (trial protocols) (intravenous)

LUMINA-1 used fixed trial-protocol dosing.

Regulatory status

Not approved. Regeneron in Phase 3 development for FOP following positive Phase 2 LUMINA-1 data showing a substantial reduction in heterotopic ossification flare-up activity. A separate clinical hold was placed and then lifted in earlier development after imbalances in deaths of uncertain attribution; subsequent LUMINA-1 data supported continuation of the program.

References

  1. [manufacturer] Regeneron Pharmaceuticals. "LUMINA-1 Phase 2 results for garetosmab in FOP," corporate press release.
  2. [pubmed] Di Rocco M, et al. "Garetosmab in fibrodysplasia ossificans progressiva: a randomized, double-blind, placebo-controlled phase 2 trial." Nat Med, 2023;29:2615-2624.

Related peptides

Bimagrumab

⚠ Monoclonal antibody — not a classical peptide. A first-in-class muscle-sparing antibody (fully human IgG1, ~150 kDa) against activin type II receptors. Combined with semaglutide in the BELIEVE Phase 2b trial (Nature Medicine, March 2026), it produced greater fat loss than semaglutide alone while preserving lean mass. Not approved; Lilly developer. Included here because it's widely discussed alongside peptides in the muscle-sparing and myostatin conversations.

Trevogrumab

⚠ Monoclonal antibody — not a classical peptide. A Regeneron anti-myostatin fully human IgG (~150 kDa) being tested as a muscle-sparing adjunct to GLP-1 therapy — CONVERGE combination program with semaglutide in obesity; earlier sarcopenia programs were deprioritized in favor of the obesity opportunity. Included here because it's widely discussed alongside peptides in muscle-sparing conversations.

ACE-031

Acceleron's first-generation myostatin trap — Phase 2 development in Duchenne muscular dystrophy was halted in 2013 after epistaxis and telangiectasia adverse events, but the same scaffold concept led to successor programs at Acceleron, Regeneron, and Lilly.
Disclaimer

This entry is for educational purposes only and does not constitute medical advice. Dosing information reflects published regulatory or research data and is not a recommendation. Many compounds described here are not approved for human use in the United States. Consult a licensed medical professional before considering any peptide therapy.