More limb-girdle case reports give Sarepta some solace

Since the Duchenne muscular dystrophy filing for Sarepta’s Vyondys 53 was knocked back by the US FDA in August the group’s stock has lost over 30%. The 7% lift this morning, from an update on the limb-girdle muscular dystrophy project Sarepta acquired through Myonexus, thus brought welcome relief. This was the first time Sarepta had detailed case reports of functional activity in the three limb-girdle type 2E subjects given a 5x1013vg/kg dose of MYO-101/SRP-9003, having in February unveiled evidence of increased beta-sarcoglycan expression and reduction in creatinine kinase – findings backing the project’s mechanism. Sarepta today said measures like subjects’ time to rise and 100m-walk test improved by 0.3-0.9 and 1.3-10.9 seconds respectively at day 270. Of course there was no comparator, so the relative benefit can only be guessed at. Sarepta provided age-matched historical controls suggesting that these measures would normally decline from baseline, and argued that it was seeing “dramatic” evidence of improvement. Only a controlled trial will actually show this; the group says three more subjects will be enrolled at a fourfold higher dose, at which point three control patients will also be recruited, before an optimal dose for a registrational study will be selected.

Functional changes in 3 subjects given initial SRP-9003 dose. NSAD: north star assessment for dysferlinopathy. Source: Sarepta.

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