— Sarepta to immediately initiate a Phase 1/2a clinical trial in patients with Duchenne muscular dystrophy (DMD) amenable to skipping exon 51 —

CAMBRIDGE, MA, USA I November 07, 2017 I Sarepta Therapeutics, Inc. (NASDAQ:SRPT), a commercial-stage biopharmaceutical company focused on the discovery and development of precision genetic medicine to treat rare neuromuscular diseases, announced today that the U.S. Food and Drug Administration (FDA) has cleared its Investigational New Drug (IND) application for the Company’s peptide phosphorodiamidate morpholino oligomer (PPMO) exon 51 candidate, SRP-5051. Sarepta will immediately initiate its Phase 1/2a clinical trial and begin screening patients with DMD amenable to skipping exon 51.

Results of the Phase 1/2a trial will inform the multi-center, double blind, placebo-controlled, multi-dose efficacy study to evaluate dystrophin expression and clinical outcomes, and is planned to initiate by mid-year 2018 or as soon as a therapeutic dose has been identified.

Sarepta’s next-generation PPMO platform is designed around a proprietary cell-penetrating peptide conjugated to the phosphorodiamidate morpholino oligomer (PMO) backbone, with the goal of increasing tissue penetration.

“Our PMO platform, on which EXONDYS 51 is based, represents precision genetic medicine that is designed to elegantly engineer the expression of dystrophin through modification of mRNA in muscle cells. Our next-generation platform, PPMO, greatly advances this science by using a proprietary peptide technology to act as a transporter of the PMO into the muscle cell, which in animal models has substantially increased mRNA modification and dystrophin production,” said Douglas Ingram, Sarepta’s president and chief executive officer. “SRP-5051, the first clinical candidate from our PPMO platform, represents a decade’s long investment and tireless work by Sarepta and its scientists. Preclinical models point to the potential of this next-generation class of chemistry to substantially increase efficacy while reducing the frequency of dosing.”

Mr. Ingram continued, “DMD is a cruel and, at least today, an invariably fatal disease. The clearance of this IND to bring SRP-5051 to the clinic is not merely a success for Sarepta. More importantly, it represents a potential approach for a better life for children living with DMD. For that reason, we intend to move urgently in further pursuit of our goal of translating promising science into potentially life-saving and life-enhancing medicines. Without delay, Sarepta will begin enrolling patients in the study to identify a safe and therapeutic dose of SRP-5051. Beyond that, we have crafted an ambitious strategy to sequence and rapidly advance multiple PPMO-based therapies designed to change the course of DMD. In parallel, if we have positive signals in our first trial, we will explore the potential of applying our PPMO technology to a broad range of other neuromuscular diseases.”

About SRP-5051

SRP-5051 uses Sarepta’s PPMO chemistry and exon-skipping technology to skip exon 51 of the dystrophin gene. SRP-5051 is designed to bind to exon 51 of dystrophin pre-mRNA, resulting in exclusion of this exon during mRNA processing in patients with genetic mutations that are amenable to exon 51 skipping. Exon skipping is intended to allow for production of an internally truncated dystrophin protein. PPMO is Sarepta’s next-generation chemistry platform designed around a proprietary cell-penetrating peptide conjugated to the PMO backbone, with the goal of increasing tissue penetration, increasing exon skipping and significantly increasing dystrophin production. If successful, the PPMO offers the potential for improved efficacy and less frequent dosing for patients.

About EXONDYS 51

EXONDYS 51 uses Sarepta’s proprietary phosphorodiamidate morpholino oligomer (PMO) chemistry and exon-skipping technology to skip exon 51 of the dystrophin gene. EXONDYS 51 is designed to bind to exon 51 of dystrophin pre-mRNA, resulting in exclusion of this exon during mRNA processing in patients with genetic mutations that are amenable to exon 51 skipping. Exon skipping is intended to allow for production of an internally truncated dystrophin protein. Data from clinical studies of EXONDYS 51 in a small number of DMD patients have demonstrated a consistent safety and tolerability profile. The pivotal trials were not designed to evaluate long-term safety and a clinical benefit of EXONDYS 51 has not been established.

Important Safety Information About EXONDYS 51

Adverse reactions in DMD patients (N=8) treated with EXONDYS 51 30 or 50 mg/kg/week by intravenous (IV) infusion with an incidence of at least 25% more than placebo (N=4) (Study 1, 24 weeks) were (EXONDYS 51, placebo): balance disorder (38%, 0%), vomiting (38%, 0%) and contact dermatitis (25%, 0%). The most common adverse reactions were balance disorder and vomiting. Because of the small numbers of patients, these represent crude frequencies that may not reflect the frequencies observed in practice. The 50 mg/kg once weekly dosing regimen of EXONDYS 51 is not recommended.

In the 88 patients who received ≥30 mg/kg/week of EXONDYS 51 for up to 208 weeks in clinical studies, the following events were reported in ≥10% of patients and occurred more frequently than on the same dose in Study 1: vomiting, contusion, excoriation, arthralgia, rash, catheter site pain, and upper respiratory tract infection.

There have been reports of transient erythema, facial flushing, and elevated temperature occurring on the day of EXONDYS 51 infusion.

For further information, please see the full Prescribing Information.

About Sarepta Therapeutics

Sarepta Therapeutics is a commercial-stage biopharmaceutical company focused on the discovery and development of precision genetic medicines to treat rare neuromuscular diseases. The Company is primarily focused on rapidly advancing the development of its potentially disease-modifying Duchenne muscular dystrophy (DMD) drug candidates. For more information, please visit www.sarepta.com.

SOURCE: Sarepta Therapeutics