The objective of this Expanded Access Program (EAP) is to provide garetosmab to patients with Fibrodysplasia Ossificans Progressiva (FOP) who have completed the double-blind treatment period of the parent study, OPTIMA (R2477-FOP-2175 [NCT05394116]), prior to marketing authorization approval, unless otherwise specified by country specific regulations for rare diseases.

The program will enroll approximately up to 55 patients, globally.

Key Inclusion Criteria:

1. Adult patients with FOP who must have completed the double-blind treatment period of the parent study OPTIMA (R2477-FOP-2175 [NCT05394116]), as defined in the protocol
2. If the patient has progression of disease with Cumulative Analogue Joint Involvement Scale (CAJIS) >19 at the time of EAP enrollment, the case will require discussion and evaluation between the treating physician and EAP Medical Director to determine final eligibility

Key Exclusion Criteria:

1. Patients participating in OPTIMA who are considered by the treating physician as inappropriate for this program for any reason

NOTE: Other protocol defined inclusion / exclusion criteria apply