Fibrodysplasia Ossificans ProgressivaPhase 3OPTIMA-2NCT07559513
A Study to Investigate the Safety, Pharmacokinetics (PK), and Efficacy of Garetosmab in Children and Adolescents With Fibrodysplasia Ossificans Progressiva (FOP)
A Phase 3 study testing garetosmab in people with Fibrodysplasia Ossificans Progressiva and FOP, run by Regeneron Pharmaceuticals.
Trial summary
This study is researching an experimental drug called garetosmab, referred to as "study drug". The study is focused on children and adolescent participants with FOP. For United States: Ages 4 to less than 18 years; for non-US sites only: Ages 2 to less than 18 years. Read more about this study
- Who is it for?
- Ages 2 to 18 years
- Conditions the study is for
- Fibrodysplasia Ossificans Progressiva, FOP
- What is being tested?
- garetosmab
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 18 participants
- Where
- No sites listed yet
- Study dates
- 2 Feb 2027to 8 Jul 2030
- Phase
- Phase 3
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 2 to 18 years
- All sexes
- No healthy volunteers
- Child, Adult
Who may be able to join
- For USA participants, age criteria are 4 to < 18 years old, at the time of the administration of the first dose of study intervention. Non-USA participants age criteria are 2 to < 18 years old
- Must have a confirmation of FOP diagnosis, as described in the protocol
- At the time of enrollment, participants must weight:
- Cohort 1: more than 30 kg (or 66.1 pounds)
- Cohort 2: more than 30 kg (or 66.1 pounds)
- Cohort 3: less than or equal to 30 kg (or 66.1 pounds)
Who cannot join
- Cumulative Analog Joint Involvement Scale (CAJIS) score > 19 at the time of screening
- Participant has significant concomitant illness or history of significant illness, as described in the protocol
- Previous history or diagnosis of cancer
- Ongoing significant viral or bacterial illness, within 2 weeks of the first study drug administration
- History of severe respiratory compromise requiring oxygen, respiratory support
- Known history of cerebral vascular malformation
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- Participants with a history of severe, non-traumatic bleeding requiring transfusion or hospitalization for hemodynamic compromise
- Participants with a known pre-existing medical history of a bleeding diathesis, as described in the protocol
- Participants who have used palovarotene in the last 30 days or within 5 half-lives of the therapy, whichever is longer from the day of randomization
- NOTE: Other Protocol-defined Inclusion/Exclusion Criteria Apply
Trial locations and contacts
No sites are listed yet. Contact the study team or a site near you to ask about taking part.
About this study
Official title: Phase 3 Evaluation of the Safety, Pharmacokinetics, and Efficacy of Garetosmab (Anti-Activin A Monoclonal Antibody) in Children and Adolescents With Fibrodysplasia Ossificans Progressiva
This study is researching an experimental drug called garetosmab, referred to as "study drug". The study is focused on children and adolescent participants with FOP. For United States: Ages 4 to less than 18 years; for non-US sites only: Ages 2 to less than 18 years.
The aim of the study is to see how safe, tolerable, and effective the study drug is.
The study is looking at several other research questions, including:
- What side effects may happen from taking the study drug
- How much study drug is in the blood at different times
- Whether the body makes antibodies against the study drug (which could make the study drug less effective or could lead to side effects)
- Conditions
- Fibrodysplasia Ossificans Progressiva, FOP
- Being tested
- garetosmab
- Keywords
- ACVR1, ACVR1 Mutation, Activin A Receptor Type 1, ALK2 Mutation, Fibrodysplasia Ossificans Congenita, FOP-causing Mutation, Heterotopic Ossification, Münchmeyer Disease, Myositis Ossificans Progressiva, Progressive Heterotopic Ossification, Progressive Myositis Ossificans, Skeletal Dysplasia, Stone Man Disease
- Medical subject headings
- Myositis Ossificans, Ossification, Heterotopic, Mucopolysaccharidosis IV
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
garetosmabDrug
Also called REGN2477, PASATRU™
Administered per the protocol
| Study group | Role | What they receive |
|---|---|---|
| Cohort 1: Adolescents | Experimental | Participants aged 12 - 18 years old Receives: Drug: garetosmab |
| Cohort 2: Children | Experimental | Children who are 4 to 12 years old (for non-US sites only 2 to 12 years old) Receives: Drug: garetosmab |
| Cohort 3: Children and Adolescents | Experimental | Participants and Children aged 4 to 18 years old (for non-US sites only 2 to 18 years old) Receives: Drug: garetosmab |
What is being measured
The primary outcome is the main question the study is designed to answer.
Occurrence of Treatment-Emergent Adverse Event (TEAEs)
Measured: Baseline to week 56
Severity of TEAEs
Measured: Baseline to week 56
Concentrations of functional garetosmab in serum
Measured: Through week 56
Secondary outcomes (16)
Total volume of new Heterotopic Ossification (HO) lesions
Measured: At week 28 and week 56
Number of new HO lesions
Measured: At week 28 and week 56
Occurrence of new HO lesions
Measured: At week 28 and week 56
Number of clinician-assessed flare-ups
Measured: Through week 28 and week 56
Occurrence of clinician-assessed flare-ups
Measured: Through week 28 and week 56
Change from baseline in total volume of HO lesions
Measured: At week 28 and week 56
Change from baseline in Tanner puberty scale
Tanner puberty scale or stages: Staging of sexual development is graded on a 5-point ordinal scale ranging from 1 (prepubertal) to 5 (adultlike) for female breast development, male external genitals, and pubic hair
Measured: At week 28 and week 56
Characteristics of menstrual cycles for female participants who reached menarche
Measured: Over 28 weeks and 56 weeks
Height-for-age Z-Scores according to the World Health Organization (WHO) Growth Reference Data for Children
Participants 5-19 years of age Z-score represents standardized measure of how far an individual deviated from study cohort average at baseline. A higher Z-score reflects better performance.
Measured: Through week 56
Change from baseline in knee height
Measured: At week 28 and week 56
Concentrations of total activin A in serum
Measured: Through week 56
Occurence of Anti-Drug Antibody (ADA) to garetosmab
Measured: Through week 56
Magnitude of ADA to garetosmab
Measured: Through week 56
Change from baseline in hearing function as assessed by audiometry
Measured: At week 28 and week 56
Change from baseline in Pediatric Quality of Life inventory (PedsQL) scores
Age-appropriate PedsQL Generic Core Scales will be used to measure HRQoL in children and adolescents. Response options include 5-point Likert scale (or 3-point Likert scale for the young children self-report) for each item asking about experience within the past week. Global scores are transformed to a 0 to 100 scale with higher scores indicating better quality of life.
Measured: At week 28 and week 56
Acceptability or tolerability assessment via exit interview
Each interview will be conducted by trained external interviewers following a semi-structured interview guide of questions for the participants about their overall experience in the trial.
Measured: Up to week 30
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted30 Apr 2026
- Study start2 Feb 2027 (estimated)
- Primary completion8 Jul 2030 (estimated)
- Study completion8 Jul 2030 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Fibrodysplasia Ossificans ProgressivaStudies of the same condition, open and under way.
- More trials run by Regeneron PharmaceuticalsThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 3
- Primary purpose
- Treatment
- Allocation
- Non-randomised
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 18 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Regeneron Pharmaceuticals
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Clinical Trial Management, Study director, Regeneron Pharmaceuticals
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07559513
- Sponsor's protocol ID
- R2477-FOP-2413
- Other IDs
- 2024-518415-19-01
- Acronym
- OPTIMA-2
- Status last verified
- Oct 2026
- First submitted
- 22 Apr 2026
- Last updated
- 20 Oct 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Yes: All Individual Patient Data (IPD) that underlie publicly available results will be considered for sharing.