Scholar Rock announced it will present data from its Phase 2 TOPAZ trial extension period evaluating patient outcomes after 24 months of treatment with apitegromab, an investigational selective inhibitor of the activation of myostatin for spinal muscular atrophy (SMA). An analysis of quality-of-life measures such as fatigue, mobility, and activities of daily living, which indicates consistency with motor function improvements observed in nonambulatory SMA patients, will be presented as an oral presentation by Thomas O. Crawford, M.D., at the Muscular Dystrophy Association (MDA) Clinical & Scientific Conference on March 22. The TOPAZ trial is an ongoing proof-of-concept, open-label Phase 2 trial evaluating the safety and efficacy of apitegromab in patients with Types 2 and 3 SMA.

In the main treatment period, patients were dosed intravenously every four weeks as monotherapy or with nusinersen, an approved SMN therapy. The trial enrolled 58 patients in the U.S. and Europe. The primary efficacy endpoints were mean change from baseline in Revised Hammersmith Scale (RHS) score at 12 months for the ambulatory population (Cohort 1), and mean change from baseline in HFMSE score at 12 months for the nonambulatory population (Cohorts 2 and 3).

The trial also includes multiple 12-month extension periods designed to evaluate longer-term patient outcomes. About Apitegromab: Apitegromab is a selective inhibitor of the activation of myostatin and is an investigational product candidate for the treatment of patients with spinal muscular atrophy (SMA). Myostatin, a member of the TGFß superfamily of growth factors, is expressed primarily by skeletal muscle cells, and the absence of its gene is associated with an increase in muscle mass and strength in multiple animal species, including humans.

Scholar Rock believes that inhibiting myostatin activation with apitegromab may promote a clinically meaningful improvement in motor function in patients with SMA. The U.S. Food and Drug Administration (FDA) has granted Fast Track, Orphan Drug and Rare Pediatric Disease designations, and the European Medicines Agency (EMA) has granted Priority Medicines (PRIME) and Orphan Medicinal Product designations, to apitegromab for the treatment of SMA. The efficacy and safety of apitegromab have not been established and apitegromab has not been approved for any use by the FDA or any other regulatory agency.