Dr. Billy Dunn was a proponent of flexibility on approving drugs in cases where the disease is very serious and the unmet medical need is high.
Wall Street may have overreacted to fears that the FDA could grow less flexible in approving certain new drugs.
Biotech investors panicked on Monday when news broke that Dr. Billy Dunn, who ran the Food and Drug Administration office that decides whether to approve drugs for neurological conditions, was retiring effective immediately.
Shares of neurology-focused biotechs dropped.
Reata Pharmaceuticals
(ticker: RETA), which was awaiting an FDA decision due the next day, plummeted 30.7%.
Dunn was the public face of the controversial accelerated approval of
Biogen
’s
(BIIB) Alzheimer’s disease therapy Aduhelm. He was seen as a standard-bearer for the FDA’s push toward more flexibility on approvals of drugs for serious neurological conditions for which few treatment options are available.
So investors worried that Dunn’s departure might signal a step toward a more conservative attitude. That could be bad news for drugmakers awaiting decisions from the agency’s neurology office, and for companies counting on that flexibility to bring their drugs to market.
In a note out on Friday, however, Citi Research analyst Neena Bitritto-Garg wrote that personnel moves at the FDA may actually signal more flexibility in certain types of approvals, rather than less. “The push to flexibility may be coming more broadly from remaining senior FDA leadership,” Bitritto-Garg wrote.
Indeed, the FDA on Wednesday said it would approve Reata’s drug Skyclarys, a treatment for an ultrarare neuromuscular disease called Friedreich’s ataxia. Reata shares jumped nearly 200% on Wednesday.
In response to a query about how Dunn’s departure would affect the agency’s approach to neurological drug approvals, an FDA official provided a copy of a letter to agency staff announcing the retirement.
“Billy has been encouraging, facilitating, and defining neurological drug development and regulation in his leadership roles,” wrote Dr. Peter Stein, Dunn’s superior as the director of the Office of New Drugs. “He has made a major impact in how drugs are developed for a range of serious neurological diseases—many that previously had only limited treatment options.”
Dunn, who served most recently as director of the FDA’s Office of Neuroscience, didn’t immediately respond to a request for comment sent to his FDA email address. He has been a proponent of the agency being more flexible in approving drugs in cases where the disease is very serious and the unmet medical need is high.
“It is clear that regulatory flexibility is a fundamental aspect of our general regulatory framework,” Dunn said at a public meeting last September of an FDA advisory committee considering an amyotrophic lateral sclerosis drug from
Amylyx Pharmaceuticals
(AMLX). The agency later approved that treatment.
In her Friday note, Bitritto-Garg traced the agency’s shift toward flexibility back to the controversial 2016 approval of
Sarepta Therapeutics
‘s (SRPT) Duchenne muscular dystrophy treatment Exondys 51. Dr. Janet Woodcock, who headed the Center for Drug Evaluation and Research and is now the FDA’s deputy commissioner, backed that call. Other FDA officials opposed it. Dr. Robert Califf, the current FDA commissioner, who also served as FDA commissioner at that time, eventually sided with Woodcock, and the drug received accelerated approval.
Bitritto-Garg, in her note, shows that many of the FDA leaders who opposed the Exondys 51 approval have since left the agency.
What is more, while Dunn took substantial public criticism for his role in the Aduhelm approval in 2021, Bitritto-Garg notes that he clearly had the backing of senior FDA leaders. Both Stein and Dr. Patrizia Cavazzoni, Woodcock’s successor as head of CDER, posted public memorandums supporting the decision as it was announced.
For Bitritto-Garg, this all suggests that the real FDA staffing moves to watch are the departures of the officials who opposed the Sarepta approval, rather than Dunn’s retirement.
“Some investors fear flexibility in CNS reviews may be over, as evidenced by share price moves earlier this week,” Bitritto-Garg wrote. “We actually believe the opposite may be true, and that his and other high-profile FDA departures recently may signal that a greater level of flexibility in CNS and some rare/genetic diseases than we’ve seen previously may be ahead.”
Write to Josh Nathan-Kazis at [email protected]
This content was originally published here.
