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Peptide Evidence Registry

Bone & calcium · Metabolic & endocrine

Garetosmab

FDA-approved in the US for the narrow adult FOP indication; metabolic and body-composition use remains investigational.

L4Good human trialsApproved for a specific indication · FDA (US)ApprovedBiologic / other
How settled this rating is:
moderate confidence in the current evidence rating
Routes studied:
Intravenous
Also known as:
Pasatru, garetosmab-grts, REGN2477, anti-Activin A antibody
Last reviewed:
2026-10-02
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Evidence passport

Garetosmab

A one-screen evidence identity for this compound. These fields describe research maturity, confidence and legal status. They are not a safety guarantee, efficacy percentage or recommendation.

Reviewed 2026-10-02
Evidence level
L4Good human trials
Confidence
Moderate confidence in rating
Regulatory status
Approved for a specific indication · See jurisdiction details
Development status
Approved

Evidence strength

Human efficacy evidence74 of 100 evidence strength

Higher = more and better-quality human evidence. It does not mean the effect is bigger or that the compound works for you.

Human safety evidence58 of 100 evidence strength

Higher = more mature, better-documented human safety data. It does not mean the compound is safer than one with a lower number.

The 0-100 values rate the strength and maturity of evidence, not how effective or safe the compound is.

Evidence base
Includes human studies
Furthest established stage
Approved
Human research maturity
US-approved for adult FOP after a controlled Phase 3 trial; metabolic/body-composition use remains investigational
Source curation
Sources fully curated

Routes recorded

IV

Overview

Human efficacy evidence strength74 of 100 evidence strength

Higher = more and better-quality human evidence. It does not mean the effect is bigger or that the compound works for you.

Preclinical (animal / lab) evidence strength76 of 100 evidence strength

Higher = more animal, tissue or cell research. Preclinical results are a starting point, not proof of a human benefit.

Human safety evidence strength58 of 100 evidence strength

Higher = more mature, better-documented human safety data. It does not mean the compound is safer than one with a lower number.

Evidence for the assessed benefit

L4Good human trialsModerate confidence in rating

Controlled Phase 3 evidence supports the narrow adult-FOP indication. Obesity/body-composition evidence is limited to an earlier 26-week COURAGE combination arm and does not establish garetosmab as an obesity treatment.

Human research context: Adults with FOP in OPTIMA for the approved use; a separate 26-week COURAGE triplet arm in adults with obesity for investigational body composition.

Research maturity, benefit evidence, safety and approval are different questions.

How to read these scores

Every number here rates the evidence, not the compound. They are editorial 0-100 strength ratings, not percentages, and not a rating out of five stars.

  • Human efficacy evidence strength — Higher = more and better-quality human evidence. It does not mean the effect is bigger or that the compound works for you.
  • Preclinical evidence strength — Higher = more animal, tissue or cell research. Preclinical results are a starting point, not proof of a human benefit.
  • Human safety evidence strength — Higher = more mature, better-documented human safety data. It does not mean the compound is safer than one with a lower number. A score of 80 does not mean “80% safe”.
  • Evidence level (L0-L5) — the strongest type of study behind the compound, from anecdote (L0) to large replicated human trials (L5). It is a description of the study evidence, not a quality, safety or recommendation rating.
  • Confidence — how likely we think it is that this rating changes as new research lands. Low confidence means the picture is unsettled, not that the compound is bad.

None of these ratings is medical advice, a safety guarantee, or a recommendation to use anything. How we grade evidence.

How far human research has progressed: US-approved for adult FOP after a controlled Phase 3 trial; metabolic/body-composition use remains investigational

Routes & formulations

Studied / approved routes

IV

The approved Pasatru product is an intravenous infusion for adults with FOP. Its formulation, clinical evidence and regulatory decision do not transfer to metabolic use.

Route availability is not evidence of efficacy, and evidence from one route does not transfer to another. The Registry never provides dosing or sourcing information.

Peptide lifecycle

  1. Discovery

  2. Preclinical

  3. Phase I

  4. Phase II

  5. Phase III

  6. Approved

Approved

Approved by FDA for adult FOP. EMA review is separate. Metabolic and body-composition research remains investigational and must not be inferred from the FOP approval.

Last documented development: 19 August 2026 — FDA approval for adults with FOP; EMA review reported as ongoing by Regeneron

What it is

A fully human monoclonal antibody that binds and neutralises Activin A. Activin A drives abnormal bone formation in FOP; its broader role in muscle and body-composition biology is being investigated separately.

What people claim

  • Reduces new heterotopic ossification lesions in adults with FOP
  • Reduces clinician-assessed FOP flare-ups
  • Improves weight loss or body composition in obesity

What the evidence actually says

Garetosmab is FDA-approved in the US for the narrow adult FOP indication; metabolic and body-composition use remains investigational. In the controlled Phase 3 OPTIMA trial in adults with fibrodysplasia ossificans progressiva, Regeneron reported 90% and 94% reductions in new CT-detected heterotopic ossification lesions at 56 weeks for the two studied doses versus placebo; clinician-assessed flare-ups were also reduced, although patient-reported flare-up proportions were not significantly different. The approval and OPTIMA efficacy apply to FOP, not obesity, weight loss, sarcopenia or reduced loss of lean mass, and they do not validate Activin A inhibition generally for muscle or metabolic outcomes. A separate 26-week COURAGE triplet arm combined garetosmab with trevogrumab and semaglutide in obesity; combination evidence cannot establish an effect of garetosmab alone. Regeneron's 1 October 2026 announcement did not report a new 52-week triplet result.

Related evidence

Useful next reads based on this compound — not recommendations.

Human evidence

  • Phase 3 OPTIMA randomised adults with active FOP to garetosmab or placebo for 56 weeks and supported the FDA approval.
  • Regeneron reported 2 versus 19 new CT-detected HO lesions with one studied dose and 1 versus 19 with the other, corresponding to 90% and 94% reductions versus placebo.
  • Clinician-assessed flare-ups were reduced in OPTIMA, but the proportion of participants reporting flare-ups was not significantly different between treatment groups and placebo.
  • The 2025 COURAGE obesity data concerned a 26-week triplet of semaglutide, trevogrumab and garetosmab. Evidence for that combination cannot be attributed to garetosmab alone.
  • No new 52-week triplet result was reported in Regeneron's 1 October 2026 trevogrumab announcement.

Preclinical evidence

  • Activin A is a documented driver of heterotopic ossification in FOP models and the biological target underlying the approved programme.
  • Body-composition rationale from Activin A signalling does not establish a metabolic treatment effect in humans.

Animal and cell findings are Level 1–2 evidence.

Mechanism and pathways

  • Neutralises Activin A, interrupting signalling involved in heterotopic bone formation in FOP.
  • Activin A signalling also intersects with muscle biology, but pathway relevance is not proof of an obesity or body-composition benefit.

Safety and unknowns

  • For the approved FOP product and population, the FDA label warns about embryo-fetal toxicity and contraindicates use in pregnancy.
  • For the approved FOP product and population, labelled warnings include skin and soft-tissue infections and spontaneous epistaxis, including serious cases requiring intervention.
  • In the FOP OPTIMA programme, common adverse reactions included abscess, acne, increased hair growth, eyebrow loss, oral ulcers, nosebleeds, folliculitis, nail infection and rash.
  • These safety findings arise from the approved FOP programme and product. They cannot simply be extrapolated to metabolic use or combinations, and they do not establish safety in those settings.

Cancer relevance

This section covers questions raised by how the compound works in the body, plus anything regulators and trial teams keep an eye on. It is not a statement that this compound causes cancer — for most compounds here, no human data exist in either direction.

Monitored in trials; not demonstrated in humans

No established human cancer signal is identified in the cited approval materials. Longer post-marketing surveillance and indication-specific trial monitoring remain relevant.

Regulatory status

Regulatory decisions apply to specific jurisdictions, products, formulations and indications. An approval elsewhere is not automatically an approval in your country.

Named regulators: FDA (US)

FDA approved Pasatru (garetosmab-grts) on 19 August 2026 to reduce formation of new heterotopic ossification lesions and clinician-assessed flare-ups in adults with fibrodysplasia ossificans progressiva (FOP). That US approval is for FOP only. The European Medicines Agency review remains separate, and garetosmab is not approved for obesity, weight loss, lean-mass preservation or body composition.

  • 2026-08-19 · United States

    FDA approved Pasatru (garetosmab-grts) to reduce formation of new heterotopic ossification lesions and clinician-assessed flare-ups in adults with FOP. This approval does not cover obesity or body-composition use; EMA review remains separate.

Key study types

  • L4Good human trialsOPTIMA Phase 3 trial in fibrodysplasia ossificans progressiva

    Randomised, placebo-controlled Phase 3 trial over 56 weeks — Adults with active FOP

    Supported the narrow US adult-FOP approval for FOP-specific lesion and clinician-assessed flare-up outcomes. It does not establish efficacy for obesity, weight loss, sarcopenia, lean-mass preservation or body composition, and it does not validate Activin A inhibition generally for muscle or metabolic outcomes.

Evidence grade

L4Good human trialsModerate confidence in rating

Completed, adequately informative controlled human trials supporting a specified outcome; replication and longer-term safety may remain uncertain.

What would change our rating?

  • Longer-term post-marketing and extension data in FOP, including functional outcomes and uncommon adverse effects.
  • A regulatory decision in Europe or another region; an ongoing review is not an approval.
  • Controlled metabolic studies capable of separating garetosmab's contribution from trevogrumab and GLP-1 therapy.

References and sources

Source transparency

A provenance snapshot of this profile. Counts show what kinds of sources are cited, not how much scientific weight each source deserves.

Sources fully curated
Last editorial review
2026-10-02
Recently reviewed · 14 days ago
Linked curated sources
4
Sources still pending
0
External specialist reviews
0
None recorded for this profile
Regulatory / label: 1Sponsor / official: 3

Review provenance

Registry editorial review: Colin Jackson-White, creator and editor, who is not a doctor or clinician. External specialist review is credited only when a named reviewer has completed a review of this exact profile.

Literature-discovery and AI tools may help locate or challenge candidate evidence, but they are not counted as evidence sources here. Registry judgements are tied to the underlying papers, trial records, regulator documents and official study records.

Source hierarchy: regulatory documents and trial registries first, peer-reviewed work next, sponsor material flagged as non-independent. We never use supplier or clinic marketing as evidence, and where a verified source has not yet been curated we say so rather than inventing one.

Evidence change history

These entries record changes to our assessment of the published evidence — not changes to the compound itself.

  1. Added the narrow FDA-approved US adult-FOP indication for Pasatru (garetosmab-grts), including the FOP-specific Phase 3 OPTIMA lesion and clinician-assessed flare-up findings. Metabolic and body-composition use remains investigational.

    Change 1 of 1
    L4Good human trials
    L4 describes research maturity for the specified FOP outcomes; regulatory approval is displayed separately and does not automatically create L5 evidence or validate Activin A inhibition for obesity, weight loss, sarcopenia or lean-mass outcomes. The earlier COURAGE evidence is from a 26-week triplet arm and cannot establish an effect of garetosmab alone. EMA review remains separate, and no new 52-week triplet result was identified. Reviewed 2 October 2026.