By Josh Nathan-Kazis

The dramatic resignation Friday night of a top Food and Drug Administration official triggered selling in biotech stocks, with shares of drugmakers Moderna and Sarepta Therapeutics tumbling early on Monday.

Dr. Peter Marks, who led the FDA's Center for Biologics Evaluation and Research, was perhaps the best-known official within the agency. His support for moving quickly to approve medicines for rare diseases has been pivotal to the fates of a long list of biotech companies.

Marks was also deeply involved in Operation Warp Speed, the effort during the first Trump administration to develop a Covid-19 vaccine. Marks famously suggested the name for the project, a nod to the Star Trek television series, of which he is reportedly a big fan.

In a resignation letter that the New York Times published Friday, Marks indicated he had stepped down over disputes with Robert F. Kennedy Jr., secretary of the U.S. Department of Health and Human Services, regarding vaccine safety,

Kennedy, a prominent vaccine skeptic, had made commitments during his confirmation process to a powerful Republican senator, Bill Cassidy, that appeared as if they would blunt his policy approach on vaccines. The Marks resignation suggests that Kennedy is continuing to push his vaccine skepticism within HHS beyond what Marks could abide.

Marks wrote that he was willing to work to address Kennedy's concerns about the safety of vaccines, but that Kennedy "wishes subservient confirmation of his misinformation and lies."

As director of CBER, Marks had been responsible for approvals of new vaccines, gene therapies, and other cutting-edge medicines.

The resignation is a bearish sign of vaccine makers. Moderna was down 10% in the premarket hours. As Barron's reported last week , the company's business has grown more precarious as vaccine skepticism has mounted. BioNTech, which partnered with Pfizer on a Covid-19 vaccine, was down 6.6%.

The news was also a setback for drugmakers that had relied on Marks's philosophy on rapid approvals for rare-disease drugs. Marks has been closely associated with approvals of Sarepta Therapeutics' medicines; that stock was down 6.9%.

Other biotechs that lost ground Monday morning included Gilead Sciences, down 2.2%, and Galapagos, off 2.5%.

"Given Dr. Marks's influence on the development of biologics and uncertainty as to who will replace him and how his legacy might continue, his departure will create a significant near-term overhang for the [small and mid-cap] biotech space, particularly for vaccine, gene therapy/editing, and cell therapy developers, until the residual impact is better understood," William Blair analyst Matt Phipps wrote Monday in a note to investors.

Write to Josh Nathan-Kazis at josh.nathan-kazis@barrons.com

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March 31, 2025 08:54 ET (12:54 GMT)

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