Apitegromab dosage and evidence
Written by Aaron CuhaReviewed Sep 2026
The short answer
Apitegromab is an antibody that blocks myostatin, a brake on muscle. The FDA is reviewing it for spinal muscular atrophy, with a decision due September 30, 2026. Added to tirzepatide, it saved 55 percent of the muscle people would have lost.
Evidence grade for Apitegromab: Preliminary. The rule: studied in people, but no published study has had people take it. The sum on this page: 2 human studies where nobody was given it. A grade counts how much has been done to people, not whether it works.
- People given it
- 0
- Human studies
- 0
- Found nothing
- 0
Dose
No human dose established
No published study on this page has given this compound to people and reported a result.
2 human studies where nobody was given it
1 effects reported, 1 wanted, by people using it, not a trial
Goal pages: Muscle and strength
In plain English
In plain English, from Aaron
This is how I would explain it to a friend. The evidence, with the numbers, is further down the page.
Apitegromab is an antibody from Scholar Rock that blocks myostatin, a brake on muscle growth. The FDA is reviewing it for spinal muscular atrophy, a muscle disease. It is also being tested to save muscle on weight loss drugs. It is not approved.
What people take it for
- Keeping muscle on tirzepatide.
- Treating spinal muscular atrophy.
What studies in people showed
In a mid-stage study with tirzepatide, adding apitegromab saved 54.9 percent of the lean mass people would have lost, or 1.9 kg. Of the weight lost, 85 percent was fat, against about 70 percent on tirzepatide alone. These figures came from the company. Nobody has shown the saved muscle makes people stronger. The FDA decision for spinal muscular atrophy is due September 30, 2026.
What people report
Reports, not study results
The good
- In the study on this page, more of the weight people lost was fat instead of muscle.
The bad
- The company report on this page does not list side effects, and we have not collected user reports on this one yet.
Where these come from: The good line is from the company release on this page. We have not collected forum or user reports for this drug yet.
My bottom line
Saving muscle on weight loss drugs is exactly the right problem. But muscle you keep is not proven strength. Right now, lifting is still the tool that works.
An opinion, not a finding. I am a coach, not a doctor.
What it has been measured to do
Measured in people
Goals Apitegromab has been tested for in people, biggest studies first. We count only what the studies on this page say, so the real numbers may be higher.
- Keeping or building muscleno headcount stated · 1 study
35 of the 36 indexed goals have no study of any kind behind Apitegromab
No study in people, animals or cells on this page reports a result for these. That does not prove Apitegromab does nothing for them. It does mean anything you have heard about Apitegromab and one of these did not come from a study cited here.
Show full evidence
What is Apitegromab?
Apitegromab is an antibody that blocks myostatin, a brake on muscle. The FDA is reviewing it for spinal muscular atrophy, with a decision due September 30, 2026. Added to tirzepatide, it saved 55 percent of the muscle people would have lost.
Apitegromab grabs myostatin before it can switch on. Myostatin holds back muscle growth, so blocking it takes the brake off. Scholar Rock filed it for spinal muscular atrophy, a muscle disease. A 2025 FDA rejection was about a factory, not the drug, and the new decision date is in September 2026. In the mid-stage EMBRAZE study in obesity, adding apitegromab to tirzepatide saved 54.9 percent of the lean mass people would have lost, or 1.9 kg. Of the weight people lost, 85 percent was fat and 15 percent lean, against 70 and 30 on tirzepatide alone.
How does Apitegromab work?
It is an antibody that holds on to myostatin in its inactive form, so it cannot switch on. That lets muscle grow.
The evidence, in charts
Fig. 1a · how many people
2studies in people cited, but none says how many people took part
number of people not stated
We do not draw a total, because none of the studies in people on this page gives one. Read the sources below for what each study measured.
We read the number of people from the source lines on this page. Where a line gives no number, we count nothing for it. We do not guess.
Fig. 1b · evidence mix
All 2 sources here are studies in people.
- Study in people · done in people2100%
Counted from the list of sources on this page. It counts only what we cite, so there may be more studies out there. A review counts once, however many studies it sums up.
Fig. 2 · evidence over time
Sources here come from just two years, 2025 and 2026.
Too few different years on this page to draw a timeline.
Fig. 3 · legal status at a glance
US
Not approved
UK
Not approved
AU
Not approved
CA
Not approved
Not approved in any of the four countries shown. This is what the law says, not a verdict on the science. See Legal status below for the full text and any notes.
Fig. 4 · how much does what
Nobody has tested different amounts in people
This chart would show how the effect changes as the amount goes up. For this compound, nobody has measured that in people. So we leave it empty. We will not borrow an animal chart and pretend it works the same in people.
Fig. 5 · what the molecule is
- Kind of compound
- Biologic
- Molecule weight
- 144,734 Da (IgG1 monoclonal antibody)
- Half-life
- Stated in words, not a numbersee the exact wording below
- Chain length
- None on file
Half-life as stated on file: Not established (antibody; monthly intravenous dosing)
No amino acid sequence is on file for Apitegromab, so none is drawn rather than guessed from a name.
The studies we cite
- Study in people2025Scholar Rock reports positive Phase 2 EMBRAZE results
Adding this antibody to tirzepatide protected about half the muscle people would otherwise have lost. It also changed what came off: 85% of the lost weight was fat, against about 70% on tirzepatide alone. Muscle loss is the main worry with these weight drugs, so this speaks straight to it. The trial was mid-stage and the figures came from the company, not a journal. Nobody has yet shown that the saved muscle makes people stronger.
Preserved 54.9% of lean mass on tirzepatide; weight lost was 85% fat.
- Study in people2026FDA review of apitegromab biologics license application
This is a regulatory date, not a result. The FDA is reviewing apitegromab for spinal muscular atrophy, a childhood muscle disease, with a decision due at the end of September 2026. An earlier rejection concerned the factory rather than the drug. None of this touches obesity, which is where the muscle-sparing interest lies, and no approval anywhere covers that use.
Decision expected September 30, 2026.
Common questions
Has Apitegromab been tested in people?
Not in a completed trial cited here. 2 human studies where nobody was given it. Apitegromab is an antibody that blocks myostatin, a brake on muscle. The FDA is reviewing it for spinal muscular atrophy, with a decision due September 30, 2026. Added to tirzepatide, it saved 55 percent of the muscle people would have lost.
What is the Apitegromab dosage?
No human dose established. No published study on this page has given this compound to people and reported a result. 2 human studies where nobody was given it
Is Apitegromab FDA-approved?
Under FDA review for spinal muscular atrophy (SMA), with a decision due by September 30, 2026; investigational in obesity
Would apitegromab be the first myostatin drug approved?
Yes, if the FDA approves it for spinal muscular atrophy in 2026. Earlier myostatin drugs failed in Duchenne muscular dystrophy and in age-related muscle loss.
Can it be used with weight-loss drugs?
Only inside studies. The EMBRAZE results are from a mid-stage study, and it is not approved for obesity anywhere.
Latest reading on Apitegromab
Blog posts about Apitegromab, newest first.