It was a big weekend for the fibrodysplasia ossificans progressiva (FOP) community at ENDO 2026, the leading global meeting on endocrinology research and clinical care hosted by the Endocrine Society.
Regeneron’s Phase 3 OPTIMA Trial
Sixty-three (63) people with FOP ≥18 years of age through 56 weeks of treatment (21 on placebo, 19 on 3 mg/kg, 23 on 10 mg/kg)
On June 13, Regeneron Pharmaceuticals shared two posters and a talk:
- Inhibition of Activin A Stops the Regrowth of Surgically Resected Heterotopic Bone in a Mouse Model of FOP
- Assessing the Participant Experience with FOP: Qualitative Interviews from the OPTIMA Trial
- Safety and Efficacy of Garetosmab in Adults with FOP: Week 56 Results from the Phase 3 OPTIMA Study
Regeneron’s conclusions slide from the talk “Safety and Efficacy of Garetosmab in Adults with FOP: Week 56 Results from the Phase 3 OPTIMA Study” detailed:
Efficacy
- Garetsomab 3 mg/kg Q4W and 10 mg/kg Q4W were efficacious in preventing formation of new heterotopic bone lesions at Week 56.
- There was a 94% and 90% reduction in the total number of new heterotopic bone lesions with garetosmab 3 mg/kg and 10 mg/kg, respectively, compared with placebo at week 56.
- Efficacy was evident as early as Week 26 (first on-treatment CT scan) and was sustained through week 56.
- Both doses demonstrated greater than 99% reduction in the total volume of new heterotopic bone lesions versus placebo.
- Garetosmab 10 mg/kg demonstrated a statically significant reduction in the rate of clinician-assessed flare-up compared with placebo at Week 56.
Safety
- Both garetosmab doses had a generally well-tolerated safety profile over the 56-week study period in people with FOP.
- There was a dose-dependent increase in skin and soft tissue infections (mostly acne and abscesses). 47% on 3 mg/kg garetosmab; 65% on 10 mg/kg garetosmab; and 33% on placebo.
- There were no deaths in the Phase 3 trial.
Fourteen (14) of the 63 participants had also participated in the LUMINA-1 study. Five were randomized to placebo, 3 on 3 mg/kg garetosmab and 6 on 10 mg/kg garetosmab.
We expect a publication in a peer-reviewed journal.
Regeneron’s latest press releases on garetosmab:
Incyte/Mirum’s Phase 2 PROGRESS Trial
Sixty-three (63) people with FOP ≥12 years of age through 48 weeks of treatment (24 weeks of placebo-controlled treatment, then 24 weeks open-label zilurgisertib)
On June 14, Incyte and Mirum shared the talk and poster:
Zilurgisertib in Patients With FOP: Interim Results From the PROGRESS Study
Incyte/Mirum’s conclusions slide detailed:
- Fewer patients taking zilurgisertib (1 of 32) had new HO lesions versus placebo (5 of 30)
- In addition, zilurgisertib demonstrated reduced volume of total HO lesions and fewer flares versus placebo
- Improvements were maintained or further improved in the OLE (open-label extension)
- Treatment with zilurgisertib was generally well tolerated, with no AEs leading to dose reduction or discontinuation
- These results support orally-administered zilurgisertib as a promising treatment option for adolescents ≥12 years old and adults with FOP
- The open-label period of PROGRESS for adolescents and adults is ongoing, and enrollment of younger age groups has begun
Incyte shared this poster and plain language summary of their results, which shows an 81% reduction in proportion of patients with new lesions at Week 24 (compared to placebo).
We expect a publication in a peer-reviewed journal.
Incyte/Mirum’s latest press releases on zilurgisertib:
If you have a question about these announcements or any of the other FOP clinical trials, email t[email protected].
