Scholar Rock announced positive results from its phase 2 TOPAZ trial extension period assessing apitegromab for nonambulatory patients with spinal muscular atrophy (SMA) types 2 and 3. The data, based on patient outcomes after 24 months of treatment demonstrate sustained improvements in motor function.

The results were presented at the Cure SMA Research & Clinical Care Meeting on June 17, 2022.

“The 24-month results provide long-term data and evidence, underscoring the findings of the 12-month primary treatment period of the TOPAZ trial in which patients receiving apitegromab experienced sizable motor function gains,” said George Nomikos, MD, PhD, senior vice president of clinical sciences and head of the muscle therapeutic area at Scholar Rock. “This durability and continued increase in motor function support the transformative potential of apitegromab for patients suffering with SMA.”

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In the phase 2 trial, apitegromab was assessed in a group of 35 nonambulatory patients with SMA types 2 and 3 aged 2 to 21 years. The primary endpoint was the mean change in Hammersmith Functional Motor Scale Expanded (HFMSE) score from baseline.

In this 24-month extension, all nonambulatory patient data were pooled and an observed case analysis was conducted. The results showed that nonambulatory patients experienced notable and sustained improvements in HFMSE score at 24 months compared to baseline. Of the 55 patients who completed the 24-month extension, 54 have decided to continue the therapy in the 36-month extension period.

As with the 12-month trial assessment, no serious safety risks of the therapy were identified at 24 months. The most common adverse effects were headache, pyrexia, upper respiratory tract infection, and nasopharyngitis, none of which were serious.


Positive phase 2 Topaz trial extension data demonstrate sizable and sustained motor function improvement at 24 months with apitegromab for non-ambulatory patients with types 2 and 3 spinal muscular atrophy (SMA). News release. Scholar Rock; June 17, 2022.