Apitegromab Preserves Lean Mass When Combined With Tirzepatide

MONDAY, June 15, 2026 — A study published online June 8 in Nature Medicine has found that apitegromab, through its selective inhibition of myostatin, can maintain lean body mass when administered in combination with tirzepatide.

Dr. Richard E. Pratley from the AdventHealth Translational Research Institute in Orlando, Florida, and his research team carried out a randomized, double‑blind Phase 2 clinical trial involving 102 adult participants who were overweight or living with obesity. Subjects were randomly divided into two groups of 51 each: one receiving tirzepatide plus apitegromab, and the other receiving tirzepatide plus placebo.

According to the research team, participants treated with apitegromab showed a least‑squares mean reduction of 1.9 kg less in lean mass loss by Week 24 compared with the placebo group, even though overall weight loss was comparable between the two study arms. This translated to a 54.9 percent higher retention rate of lean mass relative to placebo. Among those given apitegromab, trough levels of apitegromab and total latent myostatin both rose gradually over time and plateaued at approximately Week 16.

The overall incidence of adverse events was broadly similar between the apitegromab and placebo groups: adverse events were reported in 76 percent and 71 percent of participants, respectively. The rate of serious adverse events was also balanced, with one serious adverse event occurring in each treatment group.

“Findings from the EMBRAZE trial provide clinical proof of concept supporting the use of a highly selective anti‑myostatin antibody to preserve lean mass during tirzepatide treatment,” the authors stated.

Several researchers reported financial relationships with biopharmaceutical companies, including Scholar Rock — the developer of apitegromab and the sponsor of this study.