Fulcrum Sees Promise in Failed Heart Drug as Treatment for FSHD

Rare Daily Staff

Fulcrum Therapeutics said it has gained exclusive worldwide rights from GlaxoSmithKline for the experimental drug losmapimod, which Fulcrum believes has the potential to treat facioscapulohumeral muscular dystrophy, a progressive, degenerative, and disabling disorder.

Facioscapulohumeral muscular dystrophy (FSHD) typically arises in adulthood, often beginning with muscle weakness in the face, leading to an inability to smile. The weakness progresses to the upper body and advances to the lower limbs, leaving many patients unable to lift their arms above shoulder level or to rise from a sitting position. There are no approved treatments.

FSHD is caused by a single gene, DUX4, which is normally switched off at the earliest stages of embryonic development. Patients with FSHD have a mutation that causes the gene to remain “on” and to continue producing a protein toxic to muscle tissue. Losmapimod is a kinase (MAPK) inhibitor initially developed by GSK as a potential treatment for acute coronary syndrome. Fulcrum identified the compound as a potent regulator of the expression of the DUX4 gene.

Under the terms of the agreement, GSK received shares of Fulcrum preferred stock representing a high single-digit ownership percentage of the company on a fully diluted basis. GSK will be eligible to receive future milestone payments and royalties. Fulcrum obtained all worldwide development and commercialization rights for losmapimod, as well as existing drug substance and drug product materials for use in its clinical trials. Fulcrum also received a right of reference to INDs filed with the FDA relating to losmapimod and an exclusive license to all related patents and data, which build on Fulcrum-generated intellectual property.

Fulcrum expects to initiate a phase 2b clinical trial of losmapimod in mid-2019 in patients with FSHD at multiple clinical sites in the United States and Europe.

“Losmapimod is a foundational clinical asset for Fulcrum that has the potential to become the first approved therapy that targets the root cause of FSHD,” said Robert Gould, Fulcrum’s president and CEO. “Fulcrum believes losmapimod has the potential to slow or halt the progressive muscle weakness that characterizes the condition, which would significantly improve patients’ quality of life.”

Photo: Robert Gould, Fulcrum Therapeutics president and CEO