BioMarin Stocks Drop After FDA Panel is Critical of DMD Treatment Drisapersen

November 20, 2015
By Alex Keown, BioSpace.com Breaking News Staff

WASHINGTON -- BioMarin ’s dropped about 5 percent this morning following a critical analysis of the efficacy of drisapersen for the treatment of Duchenne Muscular Dystrophy by a U.S. Food and Drug Administration (FDA) advisory committee.

In August, BioMarin announced the U.S. Food and Drug Administration (FDA) had granted its drug, drisapersen, rare pediatric disease designation for Duchenne Muscular Dystrophy (DMD). Drisapersen had been granted Orphan and Fast Track status, as well as Breakthrough Therapy designation by the FDA.

This morning BioMarin announced data analysis for Kyndrisa, drisapersen, demonstrating “consistent evidence of efficacy” across three randomized studies. The materials announced this morning will be presented at the FDA hearing scheduled for Tuesday.

The FDA’s review of drisapersen was posted this morning, ahead of Tuesday’s scheduled review date. In its post, the FDA outlined a number of concerns about the efficacy of the drug, saying that in some clinical data the efficacy data is inconsistent and in other areas the data is contradictory. Members of the review panel said the long-term data presented by California-based BioMarin did not warrant approval at the time. The review panel’s recommendations are not the final arbiter for the fate of drisapersen. The committee will still hear more than two hours of testimony from patients diagnosed with Duchenne Muscular Dystrophy and their families.

If the panel proves to be a stumbling block for BioMarin, it could open the door for rival Sarepta Therapeutics , which is developing its own treatment for DMD, eteplirsen. While BioMarin’s stock took a hit this morning, Cambridge, Mass.-based Sarepta’s has jumped nearly 30 percent from$25.34 per share to $33.80 per share. Eteplirsen is designed to target the underlying cause of DMD by enabling the production of a functional dystrophin protein in patients with mutations amenable to exon 51 skipping. Approximately 13 percent of people with DMD are estimated to have a mutation targeted by eteplirsen/exon 51 skipping.

BioMarin beat Sarepta to the FDA with a New Drug Application filed in April for drisapersen. Sarepta filed its NDA for eteplirsen in June. Both drugs utilize “exon skipping” technology, which allows the damaged cells’ repair mechanisms to fix the specific genetic mutation that affects about 13 percent of individuals with the disease.

Duchenne muscular dystrophy is an X-linked degenerative neuromuscular disorder causing severe progressive muscle loss and premature death. One of the most common fatal genetic disorders, DMD affects approximately one in every 3,500 boys born worldwide. DMD is associated with specific errors in the gene that codes for dystrophin, a protein that plays a key structural role in muscle fiber function. Progressive muscle weakness in the lower limbs spreads to the arms, neck and other areas. Eventually, increasing difficulty in breathing due to respiratory muscle dysfunction requires ventilation support, and cardiac dysfunction can lead to heart failure. The condition is universally fatal, and death usually occurs before the age of 30.

Additionally, Pfizer Inc. is developing a myostatin inhibitor, PF-06252616, to treat DMD. The pharmaceutical giant is currently conducting a mid-stage clinical trial with results expected in early 2017. Pfizer’s drug may have a wider reach than the treatments being developed by Sarepta and BioMarin, which will only impact about 15 percent of patients with DMD.