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FDA Approval of AMONDYS 45 (casimersen)

SRP-9001 gene therapy DMD

Sarepta Therapeutics announces FDA approval of AMONDYS 45 (casimersen) injection to treat Duchenne muscular dystrophy (DMD) in patients amenable to skipping exon 45.

Feb. 25, 2021, >Original press release<

Sarepta Therapeutics, Inc. announced that the U.S. Food and Drug Administration (FDA) had approved AMONDYS 45 (casimersen). AMONDYS 45 is an antisense oligonucleotide from Sarepta’s phosphorodiamidate morpholino oligomer (PMO) platform, indicated for Duchenne muscular treatment dystrophy (DMD) in patients with a confirmed mutation amenable to exon 45 skipping. This indication is based on a statistically significant increase in dystrophin production in skeletal muscle observed in patients treated with AMONDYS 45, which is reasonably likely to predict clinical benefit for those patients who are exon 45 amenable. Consistent with the accelerated approval pathway, the continued approval of AMONDYS 45 may be contingent on confirmation of a clinical benefit in confirmatory trials.

 

Quickly

  • AMONDYS 45 is Sarepta’s third RNA exon-skipping treatment for DMD approved in the U.S.
  • The commercial distribution of AMONDYS 45 in the U.S. will commence immediately.
  • Information for patients and clinicians is available at www.SareptAssist.com.  

The ESSENCE trial

The ESSENCE trial is a placebo-controlled confirmatory trial to support the AMONDYS 45 approval – it is ongoing and expected to conclude in 2024.

This trial is a double-blind, placebo-controlled, multi-center Phase 3 study evaluating the efficacy and safety of casimersen (SRP-4045 as AMONDYS 45™) and golodirsen (SRP-4053, approved as VYONDYS 53™). Eligible patients with out-of-frame deletion mutations amenable to exon 45 or 53 skippings are randomized to receive once-weekly intravenous (IV) infusions of 30 mg/kg of SRP-4045 or 30 mg/kg of SRP-4053, respectively (combined-active group) or placebo for up to 96 weeks. This is followed by an open-label extension period in which all patients will receive open-label active treatment for 48 weeks, up to week 144 of the study.

Clinical efficacy is being assessed at regularly scheduled study visits, including functional tests such as the six-minute walk test (6MWT). All patients undergo a muscle biopsy at baseline and undergo a second muscle biopsy either at week 48 or week 96.

Safety is being assessed by collecting adverse events, laboratory tests, electrocardiograms (ECGs), echocardiograms (ECHOs), vital signs, and physical examinations throughout the study.

 

Doug Ingram, president and chief executive officer, Sarepta – “This is an important day for Sarepta and, far more importantly, for the patients that we serve. After years of scientific commitment, investment and development, the approval of AMONDYS 45, Sarepta’s third approved RNA therapy, offers treatment to the 8% of the DMD community who have a confirmed exon 45 amenable mutation. Along with our other approved RNA therapies, we can now offer treatment options for nearly 30% of Duchenne patients in the U.S. And our commitment to bring therapies to the greatest percentage of the DMD community as soon as possible continues.”

 

Marissa Penrod, founder of Team Joseph and parent of an 18-year old with Duchenne – “Decades of research and commitment have fueled and now accelerate our progress towards new treatments for Duchenne. “The extraordinary diligence and persistence of the Duchenne community – patients and families, clinicians and researchers – have led us to today’s approval, where we now have exon-skipping treatments for almost a third of those with Duchenne.”

AMONDYS 45 is priced at parity with Sarepta’s other approved exon-skipping treatments. Patients and physicians can access more information at www.SareptAssist.com or by calling 1-888-727-3782.

About AMONDYS 45

AMONDYS 45 (casimersen) is an antisense oligonucleotide indicated for the treatment of Duchenne muscular dystrophy in patients who have a confirmed mutation of the DMD gene amenable to exon 45 skipping. AMONDYS 45 uses Sarepta’s proprietary phosphorodiamidate morpholino oligomer (PMO) chemistry and exon-skipping technology to bind to exon 45 of dystrophin pre-mRNA, resulting in exclusion, or “skipping,” of this exon during mRNA processing in patients with genetic mutations that are amenable to exon 45 skipping. Exon skipping is intended to allow for the production of an internally truncated dystrophin protein.

AMONDYS 45 is approved under accelerated review based on an increase in dystrophin production in skeletal muscle of patients amenable to exon 45 skipping. Continued approval may be contingent upon verification of a clinical benefit in confirmatory trials.

AMONDYS 45 has met the full statutory standards for safety and effectiveness and, as such, is not considered investigational or experimental.

About Casimersen

Casimersen uses Sarepta’s proprietary phosphorodiamidate morpholino oligomer (PMO) chemistry and exon-skipping technology to skip exon 45 of the Duchenne gene. Casimersen is designed to bind to exon 45 of dystrophin pre-mRNA, resulting in exclusion, or “skipping,” of this exon during mRNA processing in patients with genetic mutations that are amenable to exon 45 skipping. Exon skipping is intended to allow for the production of an internally truncated dystrophin protein. Read more here.

About Sarepta Therapeutics

The Company has built an impressive position in Duchenne muscular dystrophy (DMD) and gene therapies for limb-girdle muscular dystrophies (LGMDs), mucopolysaccharidosis type IIIA, Charcot-Marie-Tooth (CMT), and other CNS-related disorders, with more than 40 programs in various stages of development. The Company’s programs and research focus span several therapeutic modalities, including RNA, gene therapy and gene editing. For more information, please visit www.sarepta.com or follow them on TwitterLinkedInInstagram and Facebook.

More about DMD

DMD is caused by genetic mutations that prevent dystrophin production. Patients with DMD experience progressive and irreversible muscle loss, with symptoms appearing as early as two years of age. 

Duchenne muscular dystrophy occurs primarily in males. Early signs of DMD may include delayed ability to sit, stand or walk. There is a progressive loss of mobility, and by adolescence, patients with DMD may require a wheelchair. Cardiac and respiratory muscle problems begin in the teenage years and lead to serious, life-threatening complications. Read more here.

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