RESEARCH MONOGRAPH · KDC-MN-360

Stamulumab (MYO-029)

May 9, 2026 Kodiac biolabs Research Revised May 30, 2026 2 min read

Our opinion on this compound

53/100

First anti-myostatin antibody into humans, killed by an underwhelming muscular dystrophy trial but the mechanism survived

Stamulumab (MYO-029) was the first anti-myostatin monoclonal antibody to reach human trials, developed by Wyeth in the mid-2000s. The pharmacology was reasonable on paper. Selective neutralization of mature myostatin (GDF-8), avoiding the broader ligand-trap profile of soluble receptor approaches like ACE-031.

The phase 1/2 trial in adults with various muscular dystrophies (Wagner group at Johns Hopkins, 2008) is the headline data, and the result was disappointing. Some muscle hypertrophy on MRI but no functional improvement in strength or quality of life endpoints. Wyeth wound down development shortly after. The trial got a lot of attention at the time because the myostatin knockout phenotype in mice (and the rare humans with myostatin mutations) had set very high expectations.

Honestly the lessons from MYO-029 shape how everyone has approached anti-myostatin development since. First, antibody-only myostatin neutralization seems to produce smaller effects than receptor-level blockade (later confirmed by domagrozumab, landogrozumab, trevogrumab data). Second, hypertrophy doesn't reliably translate to functional improvement in dystrophy populations where the underlying muscle pathology limits how much new mass can do. Third, you need to think about which dystrophy and what stage, because end-stage muscle is fibrotic enough that even successful hypertrophy may not deliver strength gains.

From a research standpoint, MYO-029 is mostly historical now. The proof-of-concept was that you could neutralize myostatin in humans without acute safety problems, which was a useful demonstration even though the efficacy story was a bust. The follow-on antibodies refined the selectivity and the dosing, and the field has continued.

Sourcing as a research reagent is limited. Stamulumab itself isn't broadly distributed, and most anti-myostatin antibody research now uses more recent commercial reagents (Bio X Cell makes mouse-cross-reactive options).

What we find interesting is the residual question of whether MYO-029 was just dosed too conservatively or whether antibody-only myostatin block is fundamentally weaker than receptor-trap approaches. Given the bimagrumab and ACE-031 data, we lean toward the latter, but the dose-response work in MYO-029 wasn't quite definitive.

Mostly a historical compound now. Worth knowing if you're tracing the myostatin pathway drug development arc but probably not what you reach for as a current tool.

Evidence: 45
Mechanism: 75
Reliability: 55
Safety: 75
Sourcing: 40
Value: 40
Signal: 50
Staying power: 40

Plain-language summary Intrigue 54 / 100

Stamulumab (MYO-029) is the first-in-class monoclonal antibody specifically against myostatin, developed at Wyeth (now Pfizer) and the foundational compound of the entire myostatin-blocking drug class. Unlike receptor-blocking antibodies it neutralizes only myostatin, leaving related TGF-beta ligands untouched. Phase 1 and 2 trials in adults with becker, facioscapulohumeral, and limb-girdle muscular dystrophies were the first human tests of myostatin inhibition for muscle disease. Modest muscle mass increases were observed without functional improvement, leading Wyeth to discontinue development. The compound is historically important as the proof-of-concept that opened the field. Not stocked by Kodiac. This monograph is provided for research and educational reference.

Intrigue 0–100 blends mechanism novelty, evidence strength, and translational potential. Kodiac editorial, not peer-reviewed.

Anti-myostatin monoclonal antibody (research)

A humanized monoclonal antibody selective for myostatin (GDF-8); the first-in-class anti-myostatin antibody investigated for muscular dystrophy.

Abstract

Stamulumab (MYO-029; humanized IgG1 monoclonal antibody; molecular weight approximately 145 kDa) is a humanized monoclonal antibody selective for myostatin (GDF-8), developed at Wyeth (now Pfizer). The compound binds circulating myostatin in plasma, neutralizing the negative regulator of muscle growth. Phase 1/2 trials in adults with becker muscular dystrophy, facioscapulohumeral muscular dystrophy, and limb-girdle muscular dystrophy demonstrated tolerability but limited muscle mass increases (approximately 0.5 to 1 percent), which were considered insufficient to justify advancement. The compound is the first-in-class anti-myostatin antibody and informed subsequent development of bimagrumab (broader receptor target), domagrozumab, and landogrozumab. Used as a research compound for selective myostatin neutralization.

Mechanism of action

Selective monoclonal antibody against myostatin (GDF-8); neutralizes circulating myostatin without affecting other TGF-beta family ligands.

Reported research dose ranges

Trial doses 1 to 30 mg/kg intravenous every 2 weeks.

References

Wagner KR, et al. A phase I/II trial of MYO-029 in adult subjects with muscular dystrophy. Ann Neurol 2008.
Bogdanovich S, et al. Functional improvement of dystrophic muscle by myostatin blockade. Nature 2002.
Chen JL, et al. Development of novel anti-myostatin monoclonal antibodies. Hum Gene Ther 2012.

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The full reference document is provided strictly for research use only. It reports research dose ranges from the published literature, not instructions for use in humans or animals.

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FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.

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Stamulumab (MYO-029)

Abstract

Mechanism of action

Reported research dose ranges

References

Read the full monograph

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Abstract

Mechanism of action

Reported research dose ranges

References

Read the full monograph

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