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SAREPTA THERAPEUTICS Sarepta Therapeutics ' Investigational Gene Therapy for the Treatment of Duchenne Muscular Dystrophy , SRP - 9001 , Demonstrates Robust Expression and Consistent Safety Profile Using Sarepta's Commercial Process Material 5/18/21 • Results from the first 11 participants enrolled in Study 9001-103 ENDEAVOR showed robust transduction , delivering mean vector genome copies of 3.87 per nucleus • Treated patients achieved mean micro - dystrophin expression levels of 55.4 % of normal as measured by western blot • Micro - dystrophin was properly localized to the muscle sarcolemma , with patients achieving mean percentage of dystrophin positive fibers of 70.5 % and intensity of micro - dystrophin expression of 116.9 % of normal control , as measured by immunofluorescence ( IF ) • Safety profile consistent with prior studies and no new safety signals identified CAMBRIDGE , Mass . , May 18 , 2021 ( GLOBE NEWSWIRE ) -- Sarepta Therapeutics , Inc. ( NASDAQ : SRPT ) , the leader in precision genetic medicine for rare diseases , today announced positive 12 - week expression and safety results from the first 11 participants enrolled in Study SRP - 9001-103 , an open - label study known as ENDEAVOR being conducted in partnership with Roche . In results from the first clinical study using commercially representative material , SRP - 9001 ( rAAVrh74.MHCK7.micro - dystrophin ) demonstrated robust expression of micro - dystrophin and no new safety signals from prior studies , supporting its potentially differentiated profile for the treatment of Duchenne muscular dystrophy . SRP - 9001 is an investigational gene transfer therapy intended to deliver its micro - dystrophin - encoding gene to muscle tissue for the targeted production of the micro- dystrophin protein . " We are delighted by these seminal results from the ENDEAVOR Study , our first trial results with SRP - 9001 made by our commercial - scale manufacturing process . These data show strong transduction of the micro - dystrophin gene , resulting in robust expression of the properly localized micro - dystrophin protein , and did so with no new or unexpected safety signals , " said Doug Ingram , president and chief executive officer , Sarepta . " In addition to characterizing and differentiating SRP - 9001 , these results confirm the extraordinary work done over the last two and a half years to build an at - scale gene therapy manufacturing process and corresponding analytics sufficient to meet the needs of the Duchenne population with what we believe will be a potentially life - changing therapy . Armed with these data , we will seek a meeting with the FDA with the goal of rapidly starting our registrational study . " In the open - label study , 20 participants between the ages of four and seven were treated with a single infusion of SRP - 9001 at a dose of 1.33x1014 vg / kg . In muscle biopsies from the first 11 patients taken 12 weeks after treatment , the following results were observed : • All patients demonstrated robust transduction , with mean micro - dystrophin expression of 55.4 % of normal , as measured by western blot . • Muscle dystrophin levels demonstrated a mean of 70.5 % ( baseline 12.8 % ) muscle fibers expressing micro - dystrophin at 12 weeks with a mean intensity at the sarcolemma of 116.9 % ( baseline 41.0 % ) compared to normal biopsies , as measured by immunofluorescence . Comparisons between baseline and post - treatment measures were statistically significant ( p = 0.001 for positive fibers , and p = 0.002 for intensity ) . • Mean vector genome copies per nucleus reached 3.87 . The safety profile of SRP - 9001 observed in the first 11 participants in ENDEAVOR is consistent with the safety seen in earlier studies using clinical manufacturing process material . In line with previously reported clinical data , no clinically relevant complement activation was observed in these 11 patients . Two patients experienced serious adverse events ( transaminase elevation in one patient and nausea and vomiting in a second patient ) that fully resolved . About SRP - 9001-103 ( ENDEAVOR ) Study SRP - 9001-103 ( Study 103 ) is an open - label clinical trial of SRP - 9001 that has enrolled 20 participants with Duchenne muscular dystrophy between the ages of 4-7 . Study 103 uses commercially representative SRP - 9001 and the primary endpoint is the change from baseline in the quantity of micro - dystrophin protein expression measured by western blot at 12 weeks . Secondary outcome measures include change from baseline in micro- dystrophin expression fiber intensity as measured by immunofluorescence ( IF ) and micro - dystrophin expression measured by IF percent dystrophin positive fibers at 12 weeks . Exploratory endpoints include the change in vector genome copies per nucleus , North Star Ambulatory Assessment ( NSAA ) and certain timed functional tests . Including the initial 12 - week period , patients will be followed for a total of five years . About SRP - 9001 ( rAAVrh74.MHCK7.micro - dystrophin ) SRP - 9001 is an investigational gene transfer therapy intended to deliver the micro - dystrophin - encoding gene to muscle tissue for the targeted production of the micro - dystrophin protein . Sarepta is responsible for global development and manufacturing for SRP - 9001 and plans to