Evidence review: Open Peptide Project (verified against primary PubMed, ClinicalTrials.gov & FDA records) · Last checked 2026-10-27. ← Back to Evidence Library

Garetosmab (Pasatru, REGN2477): what the evidence says

Name: Garetosmab (Pasatru, REGN2477)
Published: 2026-10-27

At a glance

What it is: a fully human antibody that blocks activin A, approved as Pasatru on Aug 19, 2026 for FOP, an ultra-rare disease in which muscle and tendon turn to bone. It is an antibody, not a peptide. ^{R1, R2, R3}

What the evidence says: Human in the OPTIMA phase 3 trial (63 adults with FOP), new bone lesions over 56 weeks fell from 19 with placebo to 1–2 with garetosmab. ^R2 An earlier phase 2 trial, LUMINA-1, came first. ^R2

Biggest risks: adverse events of special interest occurred in 17% on the higher dose vs 5% on placebo. ^R2 The FDA label warns of embryo-fetal toxicity, skin and soft-tissue infections and nosebleeds. ^R4 UNVERIFIED the COURAGE report of more bleeding when added to trevogrumab and semaglutide. ^R5

Rating


Human Human evidence	Strong: OPTIMA phase 3 RCT ^R2
Animal Animal / lab evidence	Preclinical FOP models ^R2
Regulatory	FDA-approved ^R1 · not on FDA's 503A or 503B bulk-substance category lists and not on FDA's compounding safety-risk page ^{R6, R7, R8} · banned by WADA S4.3 ^R9
Established human dose	Yes, label dose (see Study details)

Evidence verdict: Fibrodysplasia ossificans progressiva (FOP): Strong (FDA-approved; phase 3 RCT) · Obesity/muscle: Unknown

This page reports what studies used. It is not dosing advice.

Legend: HUMAN data · ANIMAL / LAB data · UNKNOWN · UNVERIFIED: not yet confirmed against a primary source

About the evidence: the trial was small because FOP is ultra-rare, but it was randomized, blinded and showed a large effect. Its use in obesity is experimental.

What is it?

Related pages: trevogrumab, bimagrumab, apitegromab, follistatin.

Does it work?

Human OPTIMA: 19 vs 1–2 new lesions (rate ratio 0.06–0.10). ^{R2, R10}
Unknown Obesity (COURAGE): no peer-reviewed data. ^R5

Is it safe?

Human Treatment-related special-interest events 17% at the higher dose; no deaths. ^R2
Label warnings: embryo-fetal toxicity, skin/soft-tissue infections, epistaxis. ^R4

Gray-market vials: extra risks

A gray-market vial has no quality control and no guarantee of identity, strength or sterility. We test retail vials blind under the Open Peptide Standard; see /tests/. A passing test covers one batch on one date and does not mean the compound is safe.

Is it legal?

US: FDA-approved (BLA 761508), prescription. ^R1
Compounding: not on FDA's 503A or 503B bulk-substance category lists and not on FDA's compounding safety-risk page. ^{R6, R7, R8}
Sport: activin A-neutralizing antibodies are banned under WADA 2026 S4.3. ^R9

Study details

These are amounts researchers used, not recommendations.

Study	People / model	Route	Amount used	Follow-up	Reported	Citation
OPTIMA phase 3 (Papa 2026)	63 adults with FOP	IV monthly	3 or 10 mg/kg	56 weeks	1–2 vs 19 new lesions	PMID 42805227

Full reference list (PubMed, CT.gov, FDA and WADA checked Oct 27, 2026)

^R1 Drugs@FDA, Pasatru (garetosmab-grts), Regeneron, original approval Aug 19, 2026, application BLA761508 (openFDA drugsfda record checked Oct 27, 2026). https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=BLA761508
^R2 Papa R, et al. Lancet. 2026. PMID 42805227
^R3 Anon. Am J Health Syst Pharm. 2026. PMID 42798232
^R4 Pasatru (garetosmab-grts) prescribing information, label published Aug 14, 2026 (DailyMed, checked Oct 27, 2026). https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=0d5cec96-b02b-4f1d-bc66-51e62ce04e3c
^R5 ClinicalTrials.gov NCT06299098, COURAGE phase 2 with trevogrumab + semaglutide (CT.gov API v2, checked Oct 27, 2026). https://clinicaltrials.gov/study/NCT06299098
^R6 FDA, 503A bulk drug substances categories list (updated May 14, 2026). https://www.fda.gov/media/94155/download
^R7 FDA, 503B bulk drug substances categories list (updated Mar 21, 2025). https://www.fda.gov/media/94164/download
^R8 FDA, Certain bulk drug substances for use in compounding that may present significant safety risks (content current Apr 22, 2026). https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks
^R9 WADA. The 2026 Prohibited List, S4.3 Agents preventing activin receptor IIB activation. https://www.wada-ama.org/sites/default/files/2025-09/2026list_en_final_clean_september_2025.pdf
^R10 ClinicalTrials.gov NCT05394116, OPTIMA phase 3, active not recruiting (CT.gov API v2, checked Oct 27, 2026). https://clinicaltrials.gov/study/NCT05394116

Disclaimer

This page is for education and harm reduction, not medical advice or a recommendation to use Garetosmab (Pasatru, REGN2477). This is a prescription medicine. Use it only under the care of a licensed clinician; do not buy it from research-chemical or gray-market sellers. Report problems to FDA MedWatch (https://www.fda.gov/safety/medwatch).