October 3, 2017
By Alex Keown, BioSpace.com Breaking News Staff
CAMBRIGDGE, Mass. – Shares of Sarepta Therapeutics have recovered from Friday’s dip of about 8 percent as investors seem to have rallied behind the company’s Duchenne muscular dystrophy (DMD) drug Exondys 51.
Last week, Sarepta’s share prices fell after safety concerns were raised regarding Exondys 51. The U.S. Food and Drug Administration’s Adverse Events Reporting System (FAERS) showed 13 serious events connected to the drug, including three deaths, Marketwatch reported. But, Leerink analyst Joseph Schwartz said in a note that the deaths and safety concerns are not believed to be associated with the drug, but rather the deadliness of DMD, Marketwatch noted.
Notes from analysts like Schwartz seemed to calm investors and when trading resumed Monday, shares of Sarepta jumped and made up for the loss. Shares climbed from Friday’s low of $44.52 to this morning’s high of $49.86 as of 10 a.m. Writing in The Motley Fool, analyst Keith Speights said investors seemed to have overreacted to the FAERS report.
“…the FAERS data doesn’t provide the full context for these adverse events. For example, FAERS doesn’t indicate if the medication caused the adverse events or contributed in any way to them. Any event that occurs with patients on prescription drugs must be reported to the FDA. FAERS simply lists all of those events, with no analysis on root causes,” Speights wrote in his column.
Speights said that the FAERS database shows that two of the patients who died were using Exondys 51 for an unknown indication in addition to treating DMD. Exondys 51, Speights noted, has only been approved for DMD. If the drug was being used off-label that was outside its approval boundaries, Speights said.
Exondys 51, formerly known as eteplirsen, was approved by the FDA for treatment of DMD in September 2016. The drug was hotly contested before it was finally approved by the FDA. Although it was ultimately approved for DMD patients, the FDA stuck a contingency on the drug. As part of the process, Sarepta will have to conduct a two-year trial to verify the drug’s benefits. Critics of the drug are concerned that Exondys 51 will not produce higher levels of dystrophin in patients.
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. The nonsense mutation is an alteration in the genetic code that prematurely halts the synthesis of an essential protein.
Exondys 51 is the only FDA-approved drug for DMD. In October 2016, one month after Exondys 51 was approved, the FDA rejected Translarna, a drug developed by PTC Therapeutics for the treatment of nonsense mutation Duchenne muscular dystrophy (nmDMD). More recently, the FDA rejected PTC’s DMD drug application as it seeks to finally net regulatory approval in the United States for ataluren. The drug has been approved in Europe.
