FDA Approves Sarepta's Second DMD Drug, Analyst Projects $500M-Plus Opportunity

After an earlier rejection, Sarepta Therapeutics Inc SRPT's Vyondys 53 received FDA approval the second time around, sending the stock sharply higher Friday.

Sarepta Succeeds On Second Try 

Cambridge, Massachusetts-based Sarepta said Thursday that the FDA granted accelerated approval for its Vyondys 53, aka golodirsen — an antisense oligonucleotide — for the treatment of Duchenne muscular dystrophy, or DMD, in patients with a confirmed mutation amenable to exon 53 skipping.

The drug was developed from Sarepta's phosphorodiamidate morpholino oligomer platform.

DMD is an ultra-rare neuromuscular condition that leads to progressive loss of muscle function.

"For 25 years, PPMD has been working with researchers, clinicians, industry, and the Duchenne community to find treatments for all people living with Duchenne," Pat Furlong, the founding president and CEO of Parent Project Muscular Dystrophy, said in a statement. 

"And while we need to ensure that these approved therapies are accessible for patients, today we celebrate this approval and thank Sarepta for their continued leadership in the fight to end Duchenne." 

Sarepta said continued approval may be contingent on confirmation of a clinical benefit in a post-marketing confirmatory trial.

In August, the FDA handed down a complete response to Sarepta's original NDA. The agency cited two concerns: the risk of infection related to intravenous infusion ports and renal toxicity in preclinical models of golodirsen that was observed following administration of other antisense oligonucleotides.

Sarepta subsequently made a formal dispute resolution request, after which the issues raised in the CRL were rapidly evaluated and resolved by the Office of New Drugs. The NDA was then resubmitted.

Expanding The Duchenne Muscular Dystrophy Addressable Market 

Vyondys 53 is Sarepta's second exon-skipping RNA therapy and is likely to treat up to 8% of DMD patients. Along with the already approved EXONDYS 51, the company now offers treatment options for about 20% of DMD patients in the U.S.

Vyondys 53 would be priced at parity with Exondys 51, the company said.

At a price of more than $600,000 for a 25kg patient on a WAC basis and with 8% of all DMD patients amenable to exon 53 skipping, Vyondys has an annual U.S. total addressable market opportunity north of $500 million, Credit Suisse analyst Martin Auster said in a note.

Sarepta said it is currently enrolling patients in a post-marketing confirmatory trial dubbed ESSENCE to support the accelerated approval of Vyondys 53, with enrollment expected to conclude by 2024.

Credit Suisse maintained an Outperform rating on Sarepta and increased the price target to $190.  

The stock was soaring 35.46% to $136.10 at the time of publication. 

Related Links:

The Daily Biotech Pulse: Second Time's The Charm For Sarepta, Pfizer's Xeljanz Snags Third Approval, NewLink Genetics Rejects Competing Offer

12 Biotech Stocks Primed For A Short Squeeze