All therapiesEvidence snapshot 2026-09-14
Muscle preservation

Apitegromab

Explore the study evidence, development history and source references.

Muscle preservation

At a glance

Selected evidence in this atlas
Studied use & population

Adults 18–65 with overweight plus a complication or obesity; diabetes excluded; predominantly women.

Study context
Approval & development

Isembyld (apitegromab-mstn) received FDA approval on September 11, 2026 for SMA in patients aged at least two already receiving an SMN2-targeted treatment. Use for muscle preservation during weight loss remains investigational. FDA highlights fracture risk and possible fetal and reproductive harms.

Status source · 2026-09-14Status & indications
Selected efficacy evidence

1.9 kg less DXA lean mass lost with apitegromab added to tirzepatide (80% CI 1.2–2.7) · 24 weeks

EMBRAZE · Nature Medicine · Both groups received tirzepatide, titrated up to 15 mg weekly. The add-on was apitegromab 10 mg/kg every four weeks or placebo. · Adjusted least-squares means in treatment completers with evaluable DXA; baseline weight/lean mass, age and sex covariates. CIs are 80%, not 95%.

Evidence & limitations
Important safety context

Nausea, fatigue and headache were numerically more frequent with apitegromab. One participant in each group had a serious adverse event.

Safety context
Next milestone

A next milestone is not summarized for this therapy.

Milestone details

Study results apply to their own population, dose and analysis. They do not establish a ranking between therapies.

Evidence in the atlas

1 result

Each result belongs to its own study population, dose and analysis. Open a result for its chart, comparator, safety findings and limitations.

Body composition

EMBRAZE

1.9 kg less DXA lean mass lost with apitegromab added to tirzepatide (80% CI 1.2–2.7) · 24 weeks

Both groups received tirzepatide, titrated up to 15 mg weekly. The add-on was apitegromab 10 mg/kg every four weeks or placebo.

Adults 18–65 with overweight plus a complication or obesity; diabetes excluded; predominantly women.

Adjusted least-squares means in treatment completers with evaluable DXA; baseline weight/lean mass, age and sex covariates. CIs are 80%, not 95%.

Safety context

Nausea, fatigue and headache were numerically more frequent with apitegromab. One participant in each group had a serious adverse event.

Through week 40 · All dosed participants: 51 per arm. The week-24 efficacy completer populations were 43 and 44.

Safety results & reporting details

Limitations: Small phase 2 completer analysis; no multiplicity adjustment. DXA lean mass is not muscle function; exploratory function showed no notable difference. Eight weeks after stopping both drugs, the lean-mass difference narrowed to 0.9 kg.

Explore result Compare study Primary study · 2026-06-08

Biology & identity

Current status: Isembyld (apitegromab-mstn) received FDA approval on September 11, 2026 for SMA in patients aged at least two already receiving an SMN2-targeted treatment. Use for muscle preservation during weight loss remains investigational. FDA highlights fracture risk and possible fetal and reproductive harms. Source

A fully human antibody that binds pro- and latent myostatin.

Uses, doses and availability depend on the formulation, indication and country. Study doses below describe research; they are not prescribing instructions.

The molecule

A fully human antibody that binds pro- and latent myostatin.
Structure not yet verified

Exact antibody structure not verified

A fully human antibody that binds pro- and latent myostatin.

Shown: Full monoclonal antibody

No exact apitegromab atomic model was verified. PDB 6UMX was checked but excluded: its Fab is 29H4-16, a high-affinity antibody variant with four CDR changes, not exact SRK-015.

Apitegromab (SRK-015)

Development timeline

Next milestone

A next milestone is not summarized for this therapy. This does not mean development has ended.

Development history2 selected milestones

Apitegromab · compound history across indications

This timeline includes selected body-composition publications and any separately sourced regulatory updates. It is not a complete development history; earlier clinical work and other indications may be missing.

  1. Publication

    EMBRAZE publication

    Apitegromab for lean mass preservation during tirzepatide-induced weight loss: a randomized, double-blind, placebo-controlled phase 2 trial

    Source
  2. Approval

    Isembyld approved for SMA in the U.S.

    For patients aged at least two already receiving SMN2-targeted treatment. This approval does not cover muscle preservation during GLP-1 treatment.

    Source

Selected sources checked Sep 14, 2026. This is not an exhaustive history.