Garetosmab

FDA-reported Week-56 results: 19 new heterotopic-ossification (HO) lesions in the placebo group (21 participants), versus 2 new lesions in the garetosmab 10 mg/kg group (23 participants) and 1 new lesion in the 3 mg/kg group (19 participants). These are lesion counts, not numbers of participants affected. Clinician-assessed flare-ups: 66 for placebo per the FDA (the sponsor's release reports 70; the reason for the difference is not established from the reviewed sources) vs. 9 (10 mg/kg) and 53 (3 mg/kg). This trial is the central Phase 3 evidence underlying the 2026 FDA approval of garetosmab-grts (Pasatru) for adult FOP.

Randomized, double-blind, placebo-controlled study using MRI thigh-muscle-volume and DXA body-composition endpoints. Combined blockade of GDF8 (trevogrumab) and Activin A (garetosmab) produced greater muscle growth than either antibody alone, accompanied by fat-mass reductions; effects tracked with antibody exposure and waned as blockade declined. This is healthy-volunteer pharmacology data, not evidence of benefit in FOP or obese populations.

Sponsor-reported Week-26 percent changes: lean mass -6.5% (semaglutide) vs -3.3% (+trevogrumab 200mg), -3.8% (+trevogrumab 400mg), -2.0% (+trevogrumab 400mg+garetosmab); fat mass -15.7% vs -17.3%/-19.1%/-27.1%; body weight -10.6% vs -9.9%/-11.1%/-13.4% respectively. Regeneron's stated interpretation: roughly one-third of semaglutide-associated weight loss in this analysis was lean mass, and trevogrumab-containing arms reduced that lean-mass loss, with the three-agent arm producing the largest lean-mass preservation and fat-mass reduction. This three-agent regimen is investigational, evaluated only within this Phase 2 trial -- not an established or routinely used obesity regimen. The sponsor's term "triplet" refers specifically to this investigational COURAGE arm, not an accepted standard of care. Sponsor-reported Week-52 results (Regeneron release dated 2026-10-01; separate lower-dose portion, trevogrumab 25 mg or 75 mg + semaglutide): lean mass -7.3% (placebo + semaglutide) vs -5.8% (25 mg) and -4.2% (75 mg) at Week 52; at Week 26 in the same portion -6.7%, -4.7% and -3.3%. These lower-dose-portion figures are a different group from the Week-26 higher-dose figures above and must not be combined with them. The sponsor states a Lancet publication is in press; no peer-reviewed publication has been reviewed.

The primary placebo-controlled endpoint (total lesion activity of pre-existing lesions) was not met (P=0.0741). Formation of new heterotopic ossification (HO) lesions was suppressed during the randomized period, a finding that informed the later Phase 3 OPTIMA design and the eventual FOP approval.

Prespecified COURAGE analysis of lean-mass effects stratified by baseline low-lean-mass status, presented at the American Diabetes Association 2026 Scientific Sessions.

Population-normed body-composition Z-score analysis of the COURAGE trial, presented at the American Diabetes Association 2026 Scientific Sessions.

Companion clinical-pharmacology analysis of garetosmab in the LUMINA-1 FOP trial population, characterizing pharmacokinetics/pharmacodynamics and supporting the dosing/exposure-response basis carried into the Phase 3 OPTIMA trial.

Double-blind, placebo-controlled first-in-human study. Acceptable safety profile with no dose-limiting toxicities; nonlinear/target-mediated pharmacokinetics described, consistent with target (Activin A) engagement.

Preclinical work bridging GDF8/Activin A blockade with GLP-1-driven weight loss in an obesity model, providing mechanistic rationale later tested in the COURAGE trial. Preclinical evidence only -- not human obesity outcome data.

FDA announcement of the approval of garetosmab-grts (Pasatru), 2026-08-19, as the second approved treatment for fibrodysplasia ossificans progressiva.

FDA's running index of Novel Drug Approvals for 2026, which includes garetosmab-grts (Pasatru).

FDA-approved label for Pasatru (garetosmab-grts): indicated for reduction in formation of new heterotopic ossification lesions and clinician-assessed flare-ups in adults with FOP. Label dosing: starting dose 10 mg/kg IV over 60 minutes every 4 weeks, may decrease to 3 mg/kg every 4 weeks if not tolerated; vial 300 mg/5 mL (60 mg/mL).

Registry record only -- no results yet. This open-label Phase 3 study will assess the safety (treatment-emergent adverse events through week 28 and week 56) and serum drug concentrations of garetosmab in children and adolescents with FOP, with efficacy as a secondary aim. It matters because the 2026 FDA approval of garetosmab-grts (Pasatru) covers adults only.

In its Form 10-Q for the quarter ended June 30, 2026, Regeneron disclosed its plan to present 52-week COURAGE trial results, including findings from an MRI substudy in a subset of participants, at the European Association for the Study of Diabetes (EASD) 2026 meeting. Update (2026-10-06): Regeneron has since issued a sponsor release dated 2026-10-01 reporting those 52-week results; see the COURAGE trial record.

Registry record for an expanded-access program providing garetosmab to adults with FOP who completed the double-blind treatment period of OPTIMA, bridging them until marketing authorization in their country (subject to country-specific rare-disease rules). It is a treatment-access program, not an efficacy study, and generates no comparative results.

A short, unauthored drug-information profile of garetosmab-grts published in a pharmacist journal about five weeks after the FDA approval of Pasatru for adult FOP. It is published without an abstract and adds no new trial data; for primary evidence see the FDA prescribing information and the OPTIMA trial.

Sponsor summary of the same 26-week COURAGE results captured in the COURAGE trial record (NCT06299098); the primary public-facing sponsor announcement of those results, dated 2025-09-17.

Sponsor announcement of positive Phase 3 OPTIMA trial results in adult FOP, dated 2025-09-17, later reflected in the FDA's Pasatru approval and label.