Mirum Pharmaceuticals announced positive results from Cohort 2 of its pivotal PROGRESS study evaluating ATEBRIOZ (zilurgisertib) in pediatric patients aged 6 to <12 years with fibrodysplasia ossificans progressiva (FOP). The study met its key endpoints, demonstrating a significant reduction in lesion volume and an improvement in joint mobility compared to placebo.
Key Details
- Primary Efficacy: At 24 weeks, zilurgisertib-treated patients experienced a mean decrease in total heterotopic ossification (HO) lesion volume of 8.09 cm³, versus a 9.14 cm³ increase for placebo (p=0.003). No patients on zilurgisertib developed new HO lesions.
- Regulatory Plans: Based on these results, Mirum plans to submit a supplemental New Drug Application (sNDA) to the FDA in the first half of 2027 to expand the drug's approval to this younger patient group.
- Drug Background & Safety: ATEBRIOZ was approved by the FDA in September 2026 for FOP patients aged 12 and older. The drug was generally well-tolerated in the new study, with a safety profile consistent with previous data.