Regeneron Says Newly Approved Drug Shows Sustained Efficacy In Halting Rogue Bone Growth

Regeneron Pharmaceuticals Inc. (NASDAQ:REGN) on Monday shared encouraging 84-week findings from the Phase 3 OPTIMA trial for its drug Pasatru (garetosmab-grts).

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The results, presented at the American Society for Bone and Mineral Research (ASBMR) Annual Meeting, demonstrate the drug’s sustained effectiveness in treating adults with fibrodysplasia ossificans progressiva (FOP).

FOP (aka stone man disease) is an ultra-rare genetic connective tissue disorder that causes muscles, tendons, ligaments, and other soft tissues to permanently transform into bone (heterotopic ossification).

This creates a “second skeleton” that progressively locks the body’s joints and restricts movement.

Sustained Efficacy In Halting Rogue Bone Growth

The longer-term data reveal that Pasatru continues to effectively halt new, abnormal bone growth and significantly reduce disease flare-ups in FOP patients.

This fully human monoclonal antibody, derived from the company’s VelocImmune technology, targets and inhibits the Activin A protein.

Regeneron scientists identified this protein as a crucial factor in the development of heterotopic ossification (HO) lesions associated with FOP.

The OPTIMA trial involved 63 adults with FOP.

Consistent Results Over 84 Weeks

The trial met its primary endpoint at 56 weeks, showing a dramatic reduction in new HO lesions and flare-ups, leading to recent FDA approval for Pasatru. The positive trend continued at the 84-week mark.

From week 56 to 84, no new HO lesions were observed in the Pasatru group, compared to nine in the placebo group.

Notably, the Pasatru 10 mg/kg dose saw only one new clinician-assessed flare-up, compared to 17 in the placebo group.

Safety and Future Plans

The safety profile of Pasatru remained generally well-tolerated through week 84, consistent with the 56-week data.

While there was a dose-dependent increase in skin and soft tissue infections, all cases were resolved with management, and no patients discontinued treatment due to infection.

Regeneron plans to initiate a Phase 3 trial, OPTIMA 2, for adolescents and children with FOP later this year.

REGN Price Action: Regeneron Pharmaceuticals shares were up 2.66% at $766.38 at the time of publication on Monday, according to Benzinga Pro data.

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