As Scholar Rock readies for SMA Phase III, investors shed shares amid varied durability data

Scholar Rock is moving apitegromab (SRK-015) into Phase III this year, but the myostatin blocker is proving to have a more durable effect in some spinal muscular atrophy patient cohorts than others.

The company’s stock fell 20% to $35.97 on Tuesday after announcing that responses to apitegromab at 12 months were improved over the six-month scores in Type 2 SMA patients at least two years old who received Spinraza before the age of five, but declined in Type 2 and non-ambulatory Type 3 patients who were older when they started Spinraza...