Deutsche Bank Questions Long-Term Efficacy Of Sarepta's Eteplirsen Following Trial News

Shares of Sarepta Therapeurics SRPT plummeted 28.2 percent Thursday morning following the long-term outcomes from the Phase IIb study of Eteplirsen.

Deutsche Bank analyst Robyn Karnauskas maintained a Hold rating on shares, as the firm waits for more information on the upcoming biopsy and FDA requirements.

Eteplirsen Phase IIb Study Meets Primary Endpoints

In a press release on Thursday, Sarepta announced data through Week 144 from Study 202, an extension study of eteplirsen in patients with Duchenne muscular dystrophy (DMD).

Sarepta wrote, "After nearly three years of follow up, results on the 6-minute walk test (6MWT) showed a decline in walking ability at a rate slower than would be expected based on available DMD natural history data. In addition, a continued stabilization of respiratory muscle function was observed, as assessed by pulmonary function tests. As previously reported, Study 202 met its primary endpoint of increased novel dystrophin as assessed by muscle biopsy at Week 48 and is now in the long-term extension phase in which patients continue to be followed for safety and clinical outcomes."

Treated Patients Have "Statistically Significant" Walking Ability Benefit from Drug

At week 144, slightly over two years and nine months, DMD patients able to perform the 6-minute walk test had an approximate 8.5 percent decline. "A statistically significant treatment benefit of 75.1 meters (p≤0.004) was observed for the mITT population compared with the placebo/delayed-treatment cohort (n=4), which initiated treatment at Week 25 following 24 weeks of placebo. After experiencing a substantial decline of 68.4 meters from baseline to Week 36, the placebo/delayed-treatment cohort demonstrated a decline of 39.0 meters in walking ability from Week 36 through Week 144, the period from which meaningful levels of dystrophin were likely produced. These analyses were based on the maximum 6MWT score when the test was performed on two consecutive days."

For investors and the general public, these numbers seem encouraging for patients and Sarepta. Jerry Mendell, M.D., director of the Centers for Gene Therapy and Muscular Dystrophy at Nationwide Children's Hospital and principal investigator of the Phase IIb study commented, "The long-term clinical data for eteplirsen showing a slowing in the decline of walking ability in a population now on average 12 years old are very encouraging, particularly when compared with the growing body of DMD natural history data which clearly show that similarly aged patients typically experience an increasingly rapid decline in walking ability and lose ambulation in their early teen years."

Deutsche Bank Questions Numbers

Despite an optimistic report, Deutsche Bank remarked on concerns regarding the meters lost from the baseline for the treated patients. Karnauskas noted the 23 to 33 meter decline from the baseline. The analyst noted, "At 120 weeks this change was -17.5mts to +4.7 mts vs. baseline. We do not know if this decline is driven by just one patient or this was seen with all patients. If this decline is across the board, there may be questions around the long term efficacy of the drug. We expect to get more color at a future medical meeting."

The data continues to suggest statistically significant results versus the placebo group. The firm emphasized that the larger declines were noted in the delayed treatment stretch over the past six months.

Respiratory Function Improvement "Provide Important Support"

Sarepta reported, "Respiratory muscle function from baseline through Week 144 in the Intent-to-Treat population (n=12), as measured by maximum inspiratory and expiratory pressure (MIP and MEP), showed a 14.7 percent mean increase in MIP and a 12.8 percent mean increase in MEP. Analyses of MIP percent predicted (MIP adjusted for weight) and MEP percent predicted (MEP adjusted for age) demonstrated a mean change from 91.7 percent at baseline to 93.9 percent at Week 144 in MIP percent predicted, and a mean change from 79.3 percent at baseline to 75.7 percent at Week 144 in MEP percent predicted."

The company added that forced vital capacity (FVC) saw a mean increase of 11 percent, versus 8.7 percent at Week 120. Adjusted for patients age and height, FVC was at 90.9 percent at Week 144 versus the 101.3 percent at baseline.

Deutsche Bank noted that, "these endpoints would provide important support to FDA filing given FDA's concerns regarding 6MWT and Dystrophin."

Stock Action

Shares of Sarepta closed at $25.89 on Wednesday. The stock plummeted to $18.59, down 28.2 percent, in Thursday morning trading. Despite regaining over half of its losses, shares are still trading down 12 percent at $22.75.