Sarepta Summary of Outstanding Questions from PPMD Webinar

On October 23, 2012, PPMD hosted a webinar with Sarepta to discuss of the 48 Week dystrophin and 6-minute walk test (6MWT) data from the Phase IIb extension study in Duchenne as well as next steps for the eteplirsen program. Chris Garabedian, President and CEO of Sarepta Therapeutics presented the data and answered submitted questions. Listed below are the outstanding questions addressed by Sarepta:

  1. What does it mean when you report results as “Mean Change From Baseline in % Dystrophin Positive Fibers”

    In the Phase 2b clinical study, we evaluated whether eteplirsen produced new dystrophin and if the protein was localized in the muscle tissue where it might be expected to have a therapeutic effect. Across all treatment arms, including the placebo/delayed-treatment arm, muscle biopsies were performed once at baseline and twice during the course of the study. A biochemical analysis of each biopsy calculated the percentage of dystrophin-positive muscle fibers by counting the number of dystrophin-positive fibers and the total number of fibers and comparing the two numbers. (Because healthy patients have 100 percent dystrophin-positive fibers, the percentage of dystrophin-positive fibers may also be called the percentage of normal). Baseline results were then subtracted from the post-treatment results to calculate the absolute change from baseline in the percentage of dystrophin-positive fibers, which we reported in recent press releases on the study data and during the PPMD Town Hall meeting.

  2. What about the safety parameters? Is there a difference between treatment and placebo on any of the adverse events?

    The safety profile of eteplirsen was evaluated across all patients through week 62 and there were no clinically significant treatment-related adverse events, no serious adverse events, and no discontinuations. One patient had a laboratory treatment-related adverse event, a transient elevation of urine protein on a urine dipstick test, however this elevation was not observed on a 24-hour urine protein measurement and resulted in no clinical symptoms or interruption of treatment. This patient did not show elevations of the specific renal markers of cystatin C or KIM-1. Across both the treatment and placebo/delayed treatment cohorts there is evidence of continued stabilization on pulmonary function tests, echocardiogram, muscle strength and clinical laboratory tests over the 62 weeks.

  3. What is your plan for pursuing additional exons?

    Our goal is to pursue exon-skipping therapeutics for all DMD patients who can benefit from our technology, including those with rare deletions. As we presented, we are actively conducting research on additional exon-skipping compounds that target exon 45, exon 50 and the recently announced EU grant for exon 53. We continue to evaluate additional partnerships and collaborations to address other exons and to move the entire platform forward. Through such collaborations we will advance clinical development with the hope of reproducing the clinical results we have seen with eteplirsen across other exon-skipping targets.

  4. What can we do to help get eteplirsen fast tracked with the FDA?

    As patients and caregivers you have a powerful voice in educating about the disease and its impact. We would recommend that parent’s connect with existing organizations that are supportive of the interests of all patients, such as PPMD, who are undertaking important initiatives to efficiently and responsibly meet patient needs. We believe by pooling your support and resources behind these types of established initiatives you will be able to effect the most change.

  5. How do I get my son involved in future trials?

    We will keep the patient community informed as we make progress on the design and planning of any additional clinical studies through organizations such as PPMD. We will also have updates on our website as well as on that will include any clinical trial information and the contact information for clinical trial sites as they open for enrollment. If a patient or family would also like to receive Sarepta updates via email please send an email to and ask to be included on our distribution list.

Sharon Hesterlee, Ph.D.
Vice President, Research
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