The Food and Drug Administration (FDA) has granted Fast Track designation to apitegromab for the treatment of patients with spinal muscular atrophy (SMA).

Apitegromab is a selective inhibitor of the inactive form of myostatin to block its activation in the muscle. Myostatin is expressed primarily by skeletal muscle cells to inhibit muscle growth. The Company believes that the inhibition of myostatin will improve motor function in patients with SMA.

The designation is supported by topline data from the 12-month phase 2 TOPAZ trial ( NCT03921528), which assessed the efficacy and safety of apitegromab administered intravenously every 4 weeks in 58 patients 2 to 21 years of age with Type 2 and Type 3 SMA. Findings showed that apitegromab demonstrated clinical improvements in motor function based on the Revised Hammersmith Scale and Hammersmith Functional Motor Scale Expanded. The most common treatment-emergent adverse events were headache, pyrexia, upper respiratory tract infection, cough, and nasopharyngitis.

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“We are delighted to receive Fast Track designation and look forward to working closely with the FDA towards our aim of establishing apitegromab as the potential first muscle-directed therapy for patients with SMA,” said Tony Kingsley, President and CEO of Scholar Rock. “We believe the recently announced top-line data from the TOPAZ phase 2 trial showed the transformative potential of apitegromab for patients with SMA.”

The FDA’s Fast Track designation allows for expedited review of therapies that are meant to treat serious or life-threatening conditions. Generally, the designation is granted to therapies that are expected to have an impact on factors such as survival and daily functioning.


  1. Scholar Rock receives Fast Track Designation from the U.S. FDA for apitegromab for the treatment of patients with Spinal Muscular Atrophy. [press release]. Cambridge, MA: Scholar Rock; May 24, 2021. 
  2. Scholar Rock announces positive 12-month top-line results from the TOPAZ phase 2 clinical trial evaluating apitegromab in patients with Type 2 and Type 3 Spinal Muscular Atrophy (SMA). [press release]. Cambridge, MA: Scholar Rock; April 6, 2021.

This article originally appeared on MPR