Scholar Rock provided the below community statement on data for apitegromab (SRK-015) following the distribution of this company press release

Dear Members of the SMA Community,

We are pleased to share 12-month topline results from our TOPAZ study, a Phase 2 clinical trial to evaluate the safety and efficacy of apitegromab (SRK-015) in individuals with Types 2 and 3 spinal muscular atrophy (SMA). TOPAZ evaluated apitegromab, mostly in conjunction with SMN upregulator therapy nusinersen, across three cohorts using motor function scales (Hammersmith scale scores).

Based on these results, and pending discussions with regulatory authorities, we plan to initiate a Phase 3 registrational trial by the end of 2021 to further investigate the efficacy and safety of apitegromab. In addition to this trial, we also plan on expanding the scope of evaluating apitegromab’s potential to populations beyond what was studied in TOPAZ.

Key findings from the TOPAZ 12-month top-line analysis include:

  • Cohort 1 evaluated apitegromab 20 mg/kg dosed every four weeks (Q4W) as monotherapy or in conjunction with nusinersen in individuals aged 5-21 years with ambulatory Type 3 SMA. At 12-months, mean change from baseline in Revised Hammersmith Scale (RHS) score was a 0.3-point decline for the full cohort. The majority of participants (57%) either maintained or improved their RHS score as reflected by a >0-point change from baseline.
  • Cohort 2 evaluated apitegromab 20 mg/kg Q4W in conjunction with nusinersen in individuals aged 5-21 years with Type 2 or non-ambulatory Type 3 SMA who had started nusinersen treatment at the age of 5 years or older. At 12 months, mean change from baseline in Hammersmith Functional Motor Scale Expanded (HFMSE) score was a 0.6-point increase. The majority of participants (64%) attained a >1-point increase from baseline, and 29% of individuals attained a >3-point increase from baseline.
  • Cohort 3 evaluated two doses of apitegromab (20 mg/kg and 2 mg/kg Q4W) in conjunction with nusinersen in children aged 2 years or older with Type 2 SMA who had started treatment with nusinersen before age 5 years. At 12-months, mean change from baseline in HFMSE score was a 7.1-point increase in children treated with the higher dose of apitegromab, and a 5.3-point increase in children treated with the lower dose. The majority of children (59%) attained a >5-point increase from baseline in HFMSE and 35% of participants attained a >10-point increase from baseline.
  • Safety: The five most frequently reported treatment-emergent adverse events were headache, pyrexia, upper respiratory tract infection, cough, and nasopharyngitis. As of these 12-month top-line results, no safety signals for apitegromab have been identified.

While there have been important advancements in recent years, individuals with Types 2 and 3 SMA continue to experience significant functional impairments, even after treatment with SMN upregulator therapies. As a muscle-directed therapy, apitegromab works differently than currently available SMN upregulator treatments. We believe the 12-month topline results support further development of apitegromab as a potential muscle-directed therapy intended to be used in conjunction with these currently available therapies to help improve motor function for individuals with SMA.

The strength and resilience of this community motivates our work every day, and we continue to seek guidance from leading physicians who treat SMA and input from the patient community as part of our efforts to advance the development of apitegromab. We are honored and privileged to work towards developing this therapy with the ultimate goal of hopefully making a difference in the lives of those with SMA and their loved ones.

Sincerely,

The Scholar Rock Team

Cambridge, MA USA

www.scholarrock.com

*Note: Apitegromab is an investigational product candidate that is currently being evaluated in a clinical trial. Apitegromab has not been approved by the U.S. Food and Drug Administration (FDA) or any other health authority, and the safety and effectiveness of this molecule have not been established.