Efficacy and Safety of Losmapimod in Treating Patients With Facioscapulohumeral Muscular Dystrophy (FSHD) (Reach)

Open to people ages 18-65

• Patients must be between 18 and 65 years of age, inclusive.
• Genetically confirmed diagnosis of FSHD 1 or FSHD 2.
• Clinical severity score of 2 to 4 (Ricci Score; Range 0-5), at screening. Patients who are wheelchair-dependent or dependent on walker or wheelchair for activities are not permitted to enroll in the study.
• Screening total relative surface area (RSA) (Q1-Q4) without weight in the dominant upper extremities (UE) assessed by reachable workspace (RWS) ≥ 0.2 and ≤ 0.7.
• No contraindications to MRI.

• Previously diagnosed cancer that has not been in complete remission for at least 5 years. Localized carcinomas of the skin and carcinoma in situ of the cervix that have been resected or ablated for cure are not exclusionary.
• Patients who are on drug(s) or supplements that may affect muscle function, as determined by the Investigator: patients must be on a stable dose of that drug(s) or supplement for at least 3 months prior to the first dose of study drug and remain on that stable dose for the duration of the study.
• Orally administered CYP3A4 substrates and MATE and OAT3 substrates are not permitted as concomitant therapy during the administration of losmapimod (defined as baseline visit through end of study treatment).
• Known active opportunistic or life-threatening infections including HIV and hepatitis B or C.
• Known active or inactive tuberculosis infection.
• Acute or chronic history of liver disease.
• Known severe renal impairment.
• History of cardiac dysrhythmias requiring anti-arrhythmia treatment(s); or history or evidence of abnormal ECGs.
• Use of another investigational product within 30 days or 5 half-lives (whichever is longer) or currently participating in a study of an investigational device.
• Current or anticipated participation in a natural history study. Previous participation is allowed but patients cannot continue after enrollment in Study 1821-FSH-301.
• Known hypersensitivity to losmapimod or any of its excipients.
• Previous participation in a Fulcrum-sponsored FSHD losmapimod study (FIS-001-2019 or FIS-002-2019).