The U.S. Food and Drug Administration said in a Complete Response Letter (CRL) to BioMarin Pharmaceutical that their Duchenne muscular dystrophy (DMD) drug drisapersen failed to meet efficacy requirements. BioMarin's DMD drug is branded as Kyndrisa.

Both DMD patient community members and researchers were angered by the recent FDA rejection. The DMD community had high hopes for drisapersen's approval. The FDA committee will talk about a similar drug called eteplirsen, created by Sarepta Therapeutics, on Jan. 22.

In November last year, the FDA advisers were not persuaded by drisapersen's effectiveness. The CRL is the result of the health agency's committee meeting wherein the drug failed to gain an approval based partly on concerns surrounding its clinical trials.

Findings of the clinical trial showed the drug did not successfully increase dystrophin levels. Dystrophin is a type of protein that helps keep muscle cells intact, and the lack or absence of it causes DMD, a genetic disease characterized by gradual muscle deterioration and weakness.

To conclude the drug's safety and efficacy, the FDA maintained the need for placebo-controlled trials for both drisapersen and eteplirsen. However, DMD patient advocates and researchers highlighted that proof of dystrophin production without major side effects should be enough to allow doctors to use the drug for treatment.

"My feeling is, it can't hurt to be approved, in the sense that it's got such a safety profile, it looks like it's efficacious and it's making protein," said researcher Lou Kunkel who worked with BioMarin's drisapersen and Sarepta's eteplirsen. "That, to me, would predict it to have an effect. And it would be a travesty not to let patients have it."

BioMarin expressed that the company is reviewing the CRL and will work with the FDA to analyze the next steps they need to make. The company also said drisapersen's ongoing trials will not be put on hold as the next step towards the drug's FDA approval is being prepared.

About one in every 3,500 to 5,000 male children is affected by DMD. The rate makes the disease one of the most prevalent fatal genetic diseases diagnosed in early life. To date, there is no FDA-approved drug for DMD treatment. Based on statistics, majority of patients die by the time they reach 30 years old.