Domagrozumab
Domagrozumab (PF-06252616), anti-myostatin monoclonal antibody
Written by Aaron CuhaReviewed Sep 2026
Also known as: PF-06252616
A properly powered phase 2 in 120 boys with Duchenne muscular dystrophy. The primary endpoint missed by 0.27 seconds at p equals 0.94, no secondary clinical endpoint differed, and both trials were terminated.
Overview
This is the most definitive negative result in the myostatin field, and it is definitive because the trial was well built. 120 ambulatory boys with Duchenne muscular dystrophy, 80 on ascending doses up to 40 mg/kg and 40 on placebo, two 48-week periods, with a functional primary endpoint and an open-label extension.
The answer was as close to nothing as a trial produces. The difference in four-stair climb time at week 49 was 0.27 seconds, with a confidence interval running from minus 7.4 to plus 7.9 seconds and a p value of 0.94. There were no significant between-group differences in any secondary clinical endpoint. Muscle volume increased non-significantly.
Pfizer terminated both phase 2 trials. Reporting this alongside the positive body composition results from other antibodies is the honest way to present the class.
Mechanism of action
A humanised monoclonal antibody against myostatin, same target and pathway as stamulumab and landogrozumab. Dosed intravenously in this programme at 5, 20 and 40 mg/kg, higher than the earlier antibodies, on the reasoning that the earlier failures reflected insufficient potency.
Human evidence
A well-powered randomised trial with a functional primary endpoint that found nothing, in the disease where myostatin inhibition has the strongest theoretical case.
- 120 boys with Duchenne muscular dystrophy, randomised 2:1 to drug or placebo, 48 weeks per period plus open-label extension.
- Primary functional endpoint, four-stair climb at week 49: difference 0.27 seconds, p = 0.94. The confidence interval spans 15 seconds, so this is not a narrowly missed effect, it is no signal.
- No significant between-group differences in any secondary clinical endpoint.
- Muscle volume increased non-significantly, consistent with the rest of the class producing tissue without capability.
- Generally safe and well tolerated, with most adverse events mild and not treatment-related.
- Both trials were terminated by the sponsor.
What this does not tell you: This result is about Duchenne muscular dystrophy, where muscle is being actively destroyed by an absent structural protein, so removing a brake on growth may simply be the wrong lever. It does not prove that myostatin inhibition cannot help a person losing muscle for a different reason, such as disuse, ageing or rapid weight loss. What it does establish is that a potent antibody at high dose, given for a year, in a disease with a clear muscle deficit, changed nothing a boy could do.
Reading the research record
Read the myostatin field as a set and one result repeats. Blocking myostatin reliably adds lean mass, by roughly a quarter to half a kilogram in the trials that measured it properly, and reliably fails to improve what a person can actually do. Stamulumab found no improvement in strength or function. Domagrozumab missed its primary endpoint and every secondary clinical endpoint. Landogrozumab added 0.43 kg of appendicular lean mass at p < 0.0001 and moved two of roughly seven physical performance measures. Bimagrumab, which this site covers separately, produced the largest body composition change in the class and did not deliver a matching functional gain either. The tissue appears. The capability does not follow.
The evidence, charted
Fig. 1 · evidence composition
3of 3 citations (100%) are in people
Every citation cited here is Human work; no other study type is cited on this page. This count is of our own citation list and understates any literature larger than the sources we cite.
Fig. 2 · evidence over time
Citations here span just two years, 2019 and 2020.
Too few distinct publication years on this page to plot as a timeline. The newest citation on file is from 2020, more than five years ago; the published record may have gone quiet.
Fig. 3 · legal status at a glance
US
Not approved
UK
Approved
AU
Not approved
CA
Not approved
Approved in 1 of 4, prescription route in 0, not approved in 3. A jurisdiction's classification is a regulatory fact, not a verdict on the science; see Legal status below for the full text and any notes.
Key studies & citations
- Human2020
Randomized phase 2 trial and open-label extension of domagrozumab in Duchenne muscular dystrophy
120 ambulatory boys aged 6 to under 16 with Duchenne muscular dystrophy, 80 on domagrozumab at 5, 20 and 40 mg/kg and 40 on placebo, two 48-week periods. Primary endpoints were safety and change in four-stair climb time at week 49. The difference in mean change was 0.27 seconds (95% CI minus 7.4 to 7.9), p = 0.94. There were no significant between-group differences in any secondary clinical endpoint. Non-significant increases in muscle volume were observed. An erratum was published in 2021.
Neuromuscular Disorders - Human2020
A study of domagrozumab in boys with Duchenne muscular dystrophy
Registry status TERMINATED. The trial reported above.
ClinicalTrials.gov - Human2019
An extension study of domagrozumab in Duchenne muscular dystrophy
Registry status TERMINATED. The open-label extension.
ClinicalTrials.gov
Frequently asked questions
Was this trial too small to find an effect?
No. That objection fits the 2008 stamulumab trial, which was explicitly underpowered. Here the point estimate was 0.27 seconds with a confidence interval from minus 7.4 to plus 7.9 and a p value of 0.94, which is the signature of no effect rather than of insufficient power.
Why did Pfizer stop it?
The public record shows both phase 2 trials with status TERMINATED and a published result with no effect on any clinical endpoint. The company's internal reasoning is not in the record and is not asserted here.
Does this kill the idea of blocking myostatin?
For Duchenne muscular dystrophy, on this evidence, it is very hard to defend. For muscle loss from other causes the question is still open, because the populations differ in ways that plausibly matter. The site's position is that four programmes have now added tissue without adding function, and anyone claiming this class preserves capability is ahead of the evidence.