Regeneron Pharmaceuticals has reported positive results from the LUMINA-1 trial of garetosmab (REGN2477) for fibrodysplasia ossificans progressiva (FOP), a very rare bone disease.

FOP leads to abnormal bone formation replacing muscles, tendons and ligaments. The disorder results in skeletal deformities and loss of mobility and can be fatal.

The Phase II, double-blind placebo-controlled trial included 44 patients from North America and Europe.

Primary analysis shows that garetosmab reduced total lesion activity compared to placebo by 25% following 28 weeks of treatment. It was driven by a 90% drop in the number of new lesions compared to placebo.

A 25% relative decrease in bone lesion volume was also noticed in the study.

The trial utilised F-NaF PET imaging and CT scans to determine the effect of garetosmab on change in heterotopic ossification (HO) among patients.

Regeneron president and chief scientific officer George D Yancopoulos said: “We believe garetosmab may offer important new hope that can potentially transform the course of FOP and look forward to working closely with the FDA and other regulatory authorities to make garetosmab available.”

The company will use detailed results from the LUMINA-1 trial for regulatory submissions. The US-based biotech also plans to undertake a paediatric trial.

Garetosmab is a VelocImmune-derived fully-human monoclonal antibody designed to neutralise Activin A. This Activin A causes abnormal heterotopic bone development in people with FOP.

In 2017, the US Food and Drug Administration (FDA) awarded ‘fast track’ designation to the candidate to prevent HO in patients with FOP.