The short answer
Adding apitegromab to tirzepatide reduced lean-mass loss in a small trial. This did not demonstrate better physical function.
How was it tested?
EMBRAZE randomized 102 adults with overweight or obesity to tirzepatide plus apitegromab or tirzepatide plus placebo. Apitegromab, an antibody targeting myostatin activation, was investigational in this study.
Kilograms less lean mass lost with apitegromab
Original chart based on the study. The result is an estimated difference, not separate group averages.
| Group or measure | Result |
|---|---|
| Apitegromab versus placebo | 1.9 kg less |
What changed?
At 24 weeks, the apitegromab group lost an estimated 1.9 kg less lean mass, despite similar total weight loss. The reported 80% confidence interval was 1.2–2.7 kg; this is narrower than the usual 95% interval.
Lean mass includes more than muscle. Exploratory physical-function assessments did not show notable differences between groups.
What are the tradeoffs?
Adverse events occurred in 39 of 51 people receiving apitegromab and 36 of 51 receiving placebo. Each group had one serious event.
The main analysis used treatment completers. Participants with diabetes were excluded, and the short, small study cannot establish long-term safety or everyday strength benefits.
Sources
Pratley and colleagues, Nature Medicine, 2026. Supported by Scholar Rock. Read the study.