Dr. Vinay Prasad, the embattled vaccine chief of the U.S. Food and Drug Administration (FDA), is once again leaving the agency — the second time in less than a year — after a series of controversial decisions involving the review of vaccines and specialty drugs for rare diseases. FDA Commissioner Marty Makary announced the news to FDA staff in an email late Friday, stating that Prasad would depart by the end of April. Prasad will return to his academic post at the University of California, San Francisco.

Controversies and Reinstatement

Prasad was briefly forced out of his role in July after clashing with biotech executives, patient advocacy groups, and conservative allies of former President Donald Trump. He was reinstated less than two weeks later, backed by Health Secretary Robert F. Kennedy Jr. and Makary. However, Prasad’s recent departure follows a string of high-profile disputes involving the FDA’s review of vaccines, gene therapies, and biotech drugs.

Over the past month, Prasad has faced criticism from pharmaceutical executives, investors, members of Congress, and other stakeholders for a series of decisions that have drawn significant backlash. His initial refusal to allow the FDA to review a highly anticipated flu vaccine from drugmaker Moderna, developed using mRNA technology, sparked immediate controversy. Moderna went public with Prasad’s decision, vowing to formally challenge it.

A week after the rejection became public, the FDA reversed course, stating it would accept the vaccine for review pending an additional study from Moderna. This reversal highlighted the agency’s shifting stance on regulatory matters under Prasad’s leadership.

Public Dispute With UniQure

In the past week, the FDA found itself in a highly unusual public dispute with UniQure, a small drug company developing an experimental treatment for Huntington’s Disease, a fatal condition affecting approximately 40,000 people in the U.S. The company stated that the FDA was demanding a new trial of its gene therapy, which would require performing a sham surgery on some patients in the trial.

UniQure executives argued that the request for a sham-controlled trial contradicted previous FDA guidance and raised ethical concerns for patients. On Thursday, the FDA held a rare press conference to criticize the company’s therapy and defend its request for an additional study. A senior FDA official, who requested anonymity, described the company’s original study as ‘stone cold negative,’ adding, ‘We have a failed product here.’

The FDA typically communicates through carefully-vetted written statements when discussing scientific disagreements, especially those involving experimental drugs. However, the public nature of this dispute marked a departure from the agency’s usual communication practices.

Prasad’s tenure as the FDA’s top vaccine and biotech regulator has been marked by a series of similar disputes with the companies the agency regulates. More than a half-dozen drugmakers studying therapies for rare or hard-to-treat diseases have received rejection letters or requests for additional studies, adding years and potentially many millions of dollars to their development timelines.

Confounding Regulatory Approach

A longtime academic and critic of the FDA’s standards for drug reviews, Prasad’s approach to regulation since arriving at the FDA last May has confounded many observers and critics. On repeated occasions, he joined Makary in announcing steps to streamline FDA drug reviews and make the process easier for companies. However, he also imposed new warnings and study requirements for some biotech drugs and vaccines, particularly those related to the COVID-19 pandemic.

These decisions have drawn particular scrutiny from Kennedy, a longtime anti-vaccine activist who joined the Trump administration as Health Secretary. Prasad’s regulatory decisions have often been at odds with Kennedy’s views on vaccine policies, adding another layer of complexity to the agency’s internal dynamics.

As Prasad prepares to leave the FDA for the second time, questions remain about the long-term impact of his tenure on the agency’s regulatory landscape and the broader implications for the pharmaceutical industry. The FDA is expected to issue a formal statement on Prasad’s departure in the coming days, though no immediate replacement has been named.