Why Scholar Rock Shares Dropped Despite Positive Apitegromab Data In Spinal Muscular Atrophy - Ionis Pharmaceuticals (NASDAQ:IONS), Scholar Rock Holding (NASDAQ:SRRK), Biogen (NASDAQ:BIIB)

Scholar Rock SRRK shares dropped despite the company reporting positive 12-month data on spinal muscular atrophy (SMA) candidate apitegromab.
The 12-month update was broadly in line with the six-month data that was announced in October last year. Most effects observed at six months have proven to be durable at 12 months.
In some cases, the efficacy results improved between the six and 12-month readouts.
A cohort of children with type 2 SMA aged two years and older who began treatment with Biogen Inc BIIB / Ionis Pharmaceuticals Inc’s IONS Spinraza (nusinersen) before turning five years old showed a mean improvement of 7.1 points on a motor scale after receiving 20-mg/kg infusions of apitegromab on top of their existing therapy.
In the 2 mg/kg dose arm, an improvement of 5.3-point was reported.
At six months, the improvement was 5.6 points and 2.4 points in 20 mg/kg and 2 mg/kg groups, respectively.
35% of the low and high-dose arm participants experienced at least a 10-point improvement on the motor function scale at 12 months. 59% of patients had a 5-point increase.
The two other cohorts lacked such evidence of enhanced responses.
In patients with type 2 or non-ambulatory type 3 SMA who began treatment with Spinraza aged five years or older, the mean increase on the motor scale at 12 months was 1.2 points. It excludes a patient who missed three apitegromab doses due to COVID-19 restrictions. At six months, the mean increase across the full cohort was 1.4 points.
A third cohort saw a worsening of the scores from six to 12 months. On another disease scale, the ambulatory type 3 SMA patients improved by 0.5 points after six months.
By 12 months, the group had experienced a mean decline of 0.3 points.
Numerical declines in the proportion of patients with three and five-point improvements were tracked.
Scholar Rock is now gearing up to evaluate apitegromab through a Phase 3 study set to start by the end of the year.
Price Action: SRRK shares are down 14.3% at $38.68 during the market trading session on the last check Tuesday.

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