Sarepta Therapeutics Announces Eteplirsen Demonstrates a Continued Benefit on Walking Test Through 84 Weeks in Phase IIb Study in Duchenne Muscular Dystrophy
Sarepta Therapeutics, Inc. (NASDAQ: SRPT), a developer of innovative RNA-based therapeutics, announced updated data from Study 202, a Phase IIb open-label extension study of eteplirsen in patients with Duchenne muscular dystrophy (DMD). Results at 84 weeks showed a continued stabilization of walking ability in eteplirsen-treated patients evaluable on the 6-minute walk test (6MWT). 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. Eteplirsen is Sarepta’s lead exon-skipping compound in development for the treatment of patients with DMD who have a genotype amenable to skipping of exon 51.
After 84 weeks, patients in the 30 mg/kg and 50 mg/kg dose cohorts who were able to perform the 6MWT (modified Intent-to-Treat or mITT population; n=6) showed a statistically significant treatment benefit of 46.4 meters (p less than or equal to 0.045) when compared to the placebo/delayed-treatment cohort (n=4). The eteplirsen-treated patients in the mITT population demonstrated less than a 6 percent decline (20.5 meters) from baseline in walking ability. After experiencing a substantial decline earlier in the study, the placebo/delayed-treatment cohort also demonstrated stabilization in walking ability from Week 36 through 84, the period from which meaningful levels of dystrophin were likely produced, with an increase of 3.3 meters over this timeframe. These analyses were based on the maximum 6MWT score when the test was performed on two consecutive days.
“We now have demonstrated stability of walking for over a year and a half in the original eteplirsen treatment cohort in boys who are now 11 years old on average, an age when many DMD boys have lost the ability to walk,” said Chris Garabedian, president and chief executive officer of Sarepta Therapeutics. “In addition, the placebo/delayed-treatment cohort, which has now received eteplirsen for over a year, has demonstrated a stabilization in walking ability for 48 weeks compared with the precipitous decline observed earlier in the study before dystrophin was confirmed in these patients. Overall, we believe the data across all treatment cohorts are remarkably consistent and continue to support eteplirsen as a potential treatment option in DMD.”
Through 84 weeks, eteplirsen was well tolerated and there were no clinically significant treatment-related adverse events, no serious adverse events, hospitalizations or discontinuations.
One boy in the placebo/delayed-treatment cohort was not able to perform the 6MWT at the Week 84 clinic visit due to a physical injury unrelated to treatment, and therefore had no 6MWT data captured at the Week 84 time point. The boy has recovered from the injury, continues to be ambulatory and is expected to be evaluated on the 6MWT at future clinic visits.
Across all patients in the eteplirsen and placebo/delayed-treatment cohorts (Intent-to-Treat or ITT population), there is evidence of continued stabilization on clinical laboratory tests, echocardiograms, pulmonary function tests and measures of muscle strength.
Summary of Additional 6MWT Analyses
Patients performed two 6MWT evaluations on consecutive days at time points coinciding with a muscle biopsy procedure at baseline and Weeks 12, 24 and 48. All other evaluations were a single 6MWT. The pre-specified primary analysis included the maximum distance walked at those clinic visits where repeated tests were taken. Other analyses of the repeated 6MWT results assessed mean, minimum, and Day 1 (first measure) scores. Results from these additional 6MWT analyses confirm the robust treatment effect observed in the primary analysis.