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Sarepta shares first results on next-generation Duchenne drug

Dive Brief:

  • Sarepta Therapeutics on Monday said an experimental, second-generation therapy for Duchenne muscular dystrophy showed promise in its first clinical trial.


  • According to Sarepta, early results from the Phase 2 dosing study suggest the therapy, known as SRP-5051, may be more powerful at a lower dose than the company’s marketed drug, Exondys 51. Sarepta received approval for Exondys in 2016, despite a dramatic dispute within the Food and Drug Administration.


  • Analysts called the results encouraging, but cautioned that the variable dosing and small number of patients involved in the early analysis make drawing solid conclusions difficult.


Dive Insight:

Sarepta claims the SRP-5051 study demonstrates proof of concept for the company’s new technology, which is designed to increase cell penetration, giving patients a more effective treatment with an easier dosing regimen.

In addition to SRP-5051, the Cambridge, Massachusetts-based biotech has designed five other potential therapies using this platform. Sarepta said the latest results give it confidence to continue advancing the technology and to study it for other diseases.

Sarepta’s Duchenne medicines work by blocking a genetic mutation that prevents the body from making a muscle-building protein called dystrophin. In the case of Exondys 51 and SRP-5051, the target is a stretch of the DMD gene known as exon 51.

Sarepta said one arm of the SRP-5051 study saw especially favorable results from a 20 mg/kg dose given monthly, in comparison with a 30 mg/kg dose of Exondys 51 given weekly. Those results, along with animal data, could suggest even more efficacy for SRP-5051 at higher doses, SVB Leerink analyst Joseph Schwartz wrote in a note to investors.

The biotech also said it didn’t see negative effects on the kidney, a finding that analysts said is crucial because one concern surrounding its technology is kidney toxicity.

Sarepta has a second Duchenne treatment called Vyondys 53 already on the market, and is seeking approval for a third, called casimersen. Those two drugs go after different pieces of the DMD gene — exon 53 and exon 45, respectively.

The company is also developing a different type of gene therapy called SRP-9001 for Duchenne. A study of that treatment is expected to produce data in the first quarter of next year and is likely to have a bigger effect on the company’s future value, according to Danielle Brill, an analyst at Raymond James.