Scholar Rock Presents TOPAZ Phase 2 Data Showing the Transformative Potential of Apitegromab in Patients with Type 2 and 3 Spinal Muscular Atrophy (SMA) at the 2021 Virtual SMA Research & Clinical Care Meeting

Scholar Rock (NASDAQ: SRRK), a clinical-stage biopharmaceutical company focused on the treatment of serious diseases in which protein growth factors play a fundamental role, today announced an oral presentation of TOPAZ Phase 2 trial results by the lead principal investigator, Thomas Crawford, M.D. of Johns Hopkins Medicine, at the Cure SMA Annual SMA Conference. In the TOPAZ trial, treatment with apitegromab in conjunction with nusinersen in patients with Type 2 and 3 SMA led to meaningful motor function improvements of up to 20 points as measured by HFMSE. New exploratory analyses being presented further support apitegromab’s potential to improve motor function in patients with SMA.

“The TOPAZ results show that apitegromab has promising potential to benefit the large portion of individuals with SMA who still manifest muscle weakness,” said Thomas Crawford, M.D., Professor of Neurology at the Johns Hopkins School of Medicine and Lead Investigator of the TOPAZ trial. “In recent years, there have been some really remarkable advances in therapy for SMA that increase the low levels of SMN protein in motor neurons. But these findings suggest the fortunate streak for SMA therapeutics can potentially continue, this time targeting the persistent weakness in a complementary fashion at the level of muscle.”

SMA remains a devastating and debilitating disease despite the utilization of SMN upregulators that prevent further motor neuron deterioration. A muscle-directed approach such as apitegromab, a selective inhibitor of myostatin activation, has the potential to complement SMN upregulators and address motor function impairments in patients with SMA. Scholar Rock’s TOPAZ Phase 2 trial (NCT03921528) evaluated apitegromab across a broad age range (2-21 years) of patients with Type 2 and 3 SMA. With the exception of some ambulatory patients who received apitegromab as a monotherapy, patients enrolled in TOPAZ were receiving chronic maintenance doses of nusinersen. Both non-ambulatory cohorts had received more than 5.0 mean maintenance doses or approximately 2 years of treatment at baseline. Clinical data from the CHERISH and SHINE studies of nusinersen offer background insights into this patient population.¹ These studies observed that nusinersen-treated patients primarily experienced stabilization or only slight increases in HFMSE scores beyond the initial 15-month treatment period.² In addition, even in the initial 15-month treatment period, patients who initiated nusinersen treatment age ≥5 on average experienced declines in HFMSE and rarely attained a ≥3-point increase in HFMSE in a 12-month timeframe.³