Sanofi bets $80M on Fulcrum's muscular dystrophy drug

Sanofi has recently expanded its rare disease treatment portfolio by agreeing to acquire partial rights to an experimental drug being developed by Fulcrum Therapeutics for a type of muscular dystrophy. The agreement, finalized on Monday, involves Sanofi paying Fulcrum $80 million for rights outside the United States to the medicine known as losmapimod. Additionally, Fulcrum stands to gain up to $975 million in future payments and royalties on international sales, while both companies will share development costs.

Losmapimod is currently in Phase 3 clinical trials for treating facioscapulohumeral muscular dystrophy (FSHD), a rare genetic disorder characterized by muscle weakness. Although the drug did not succeed in a Phase 2 trial, a subsequent analysis suggested potential benefits on a functional measure, which has now become the central focus of the ongoing late-stage trial. Results from this trial are anticipated later in the year.

Initially owned by GSK, losmapimod was originally aimed at preventing heart attacks in individuals with cardiovascular disease. However, Fulcrum Therapeutics, then a privately-held biotech startup, obtained the licensing rights in 2019 to explore a different therapeutic approach. Fulcrum began investigating losmapimod's effectiveness against FSHD, which specifically weakens the muscles of the face, shoulders, and arms. The drug functions by inhibiting an enzyme that contributes to the production of DUX4, a protein implicated in the disease's progression.

Since going public, Fulcrum has advanced losmapimod into Phase 3 trials, though not without encountering some hurdles. Data supporting the drug have been inconsistent, and the company has experienced multiple leadership changes. Furthermore, another experimental therapy from Fulcrum, aimed at treating sickle cell disease, has faced regulatory setbacks.

Despite these challenges, Fulcrum now enjoys the backing of Sanofi as it approaches the final stages of testing losmapimod for FSHD. The Phase 3 trial seeks to determine if the drug can significantly enhance patients' reachable workspace, a metric of their range of motion. The trial involves 260 participants who were initially randomized to receive either losmapimod or a placebo for 48 weeks. Subsequently, those who were given the placebo were switched to Fulcrum's drug.

Meanwhile, Fulcrum faces competition from Avidity Biosciences, which is developing an RNA-based treatment for FSHD currently in early-stage trials. Preliminary results from Avidity's study are expected by the end of June.

Sanofi's collaboration with Fulcrum brings an experienced partner into the fold, particularly in the marketing of neuromuscular and rare disease therapies. The French pharmaceutical giant already markets two treatments for multiple sclerosis and several therapies for lysosomal storage disorders, underscoring its established presence in the field of rare diseases.

In summary, Sanofi's acquisition of partial rights to Fulcrum's experimental drug losmapimod marks a significant step in addressing the unmet needs of patients with FSHD. With upcoming trial results and Sanofi's extensive experience, there is cautious optimism about the potential impact of this partnership in the realm of rare disease treatment.