Sarepta Therapeutics SRPT announced plans to submit supplementary new drug applications (sNDAs) to the FDA for its two RNA-based PMO therapies — Amondys 45 and Vyondys 53 — by the end of next month. These filings seek to convert the therapies’ accelerated approval into full/traditional approvals.
Both therapies were previously granted accelerated approval to treat patients with Duchenne muscular dystrophy (DMD) based on increases in dystrophin production. Sarepta now intends to support the sNDAs with additional data, including real-world evidence, as part of its effort to confirm clinical benefit.
Amondys 45 was approved in 2021, while Vyondys 53 received approval in 2019. Both are currently approved under the FDA’s accelerated pathway for DMD patients amenable to exon 45 or 53 skipping.
This update follows challenges with the confirmatory study, which did not meet its primary endpoint. The FDA will evaluate the totality of evidence, including both clinical and real-world data, to determine whether the therapies meet the requirements for traditional approval.
Details From Sarepta’s Confirmatory Study
In November, Sarepta announced the completion of the phase III ESSENCE study, which evaluated the safety and efficacy of Amondys 45 and Vyondys 53 compared to placebo in DMD patients aged 6-13 who are amenable to exon 45 or 53 skipping. While the company noted positive numerical trends favoring both therapies at 96 weeks, the study did not achieve statistical significance on its primary endpoint.
Sarepta attributed the lack of statistical significance, in part, to the COVID-19 pandemic, stating that when COVID-affected data were excluded, a meaningful treatment effect on the primary endpoint was observed. The ESSENCE study reaffirmed a favorable safety profile for both therapies.
Some investors viewed the update as encouraging, as it suggests a potential pathway for the therapies to pursue full approval despite the confirmatory study not meeting its primary endpoint.
SRPT Stock's Performance
In the past year, shares of Sarepta have plunged nearly 78% against the industry’s 11% growth.
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Will Sarepta’s Stock Head Toward Recovery?
Last year, Sarepta faced significant investor concerns after three patient deaths were linked to its gene therapy treatments and attributed to acute liver failure (ALF). While two deaths occurred in patients after receiving the DMD gene therapy Elevidys, one was caused by an experimental limb-girdle muscular dystrophy (LGMD) therapy. All deaths occurred in non-ambulatory patients and were linked to the AAVrh74 gene therapy vector used in both Elevidys and Sarepta’s experimental LGMD therapies.
Based on these events, the FDA approved significant changes to the label of Elevidys last November. Under the revised label, the gene therapy is now approved only for ambulatory patients aged four years and older with DMD. It is no longer authorized for use in non-ambulatory patients. Elevidys is mandated to carry a boxed warning — the most important safety warning issued by the FDA — highlighting the risks of ALF and acute liver injury (ALI).
Following these setbacks, Sarepta paused the development of most of its LGMD pipeline and shifted focus to the siRNA programs, which were acquired last year as part of a multi-billion-dollar licensing deal with Arrowhead Pharmaceuticals ARWR.
Sarepta has been trying to ease investor sentiment toward its stock. Earlier this week, the company announced that screening and enrollment are underway in a cohort of the phase Ib ENDEAVOR study. This cohort is designed to improve the safety profile of Elevidys in non-ambulatory patients by combining it with an enhanced sirolimus-based immunosuppressive regimen.
Data from this cohort will be used to determine whether administering sirolimus before or after Elevidys infusion can help reduce the risk of acute liver complications. Sarepta plans to enroll around 25 non-ambulatory patients with DMD in the United States who will receive the immunosuppressive regimen. This will include 14 days of sirolimus dosing before Elevidys infusion, followed by 12 weeks of treatment after infusion.
The company developed Elevidys in partnership with pharma giant Roche RHHBY. In 2019, Sarepta and Roche entered into a licensing agreement to develop Elevidys. Per the agreement, Roche has exclusive rights to launch and market the therapy in non-U.S. markets.
Sarepta Therapeutics, Inc. Price
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SRPT’s Zacks Rank
Sarepta currently carries a Zacks Rank #3 (Hold). You can see the complete list of today’s Zacks #1 Rank (Strong Buy) stocks here.
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This article originally published on Zacks Investment Research (zacks.com).