Scholar Rock has reported extension data evaluating patient outcomes after 36 months from the Phase II TOPAZ trial of apitegromab for the treatment of spinal muscular atrophy (SMA), a rare, and often fatal genetic disorder that manifests in young children, typically.

Designed to assess the safety and efficacy of apitegromab, the ongoing proof-of-concept, open-label study has enrolled 58 patients in the US and Europe with Types 2 and 3 SMA.

An approved SMN therapy, nusinersen or an intravenous infusion of monotherapy for every four weeks was given to patients during the main treatment period.

Mean change from baseline in Revised Hammersmith Scale (RHS) score at 12 months for the ambulatory population (Cohort 1) was the primary efficacy endpoint of the study.

Mean change in HFMSE score for the non-ambulatory population (Cohorts 2 and 3) was also considered as the primary endpoint.

Furthermore, longer-term patient outcomes will be evaluated in multiple 12-month extension periods of the study.

Scholar Rock president and CEO Jay Backstrom said: “As we progress enrolment of our Phase III SAPPHIRE trial toward completion this year, we are excited to share the 36-month data from the Phase II TOPAZ study, the longest efficacy and safety data on an anti-myostatin in SMA to date.

“These data continue to deepen our understanding of the essential role a selective muscle-targeted treatment could play in transforming care in spinal muscular atrophy, and we look forward to sharing the 36-month TOPAZ data with the community at the Cure SMA Annual Conference.”