The White House has ruled out acting Food and Drug Administration Commissioner Janet Woodcock as a nominee for the agency's permanent chief, Bloomberg news reported, leaving the role unfilled seven months into President Joe Biden's term as the regulator prepares to make key decisions on coronavirus vaccines and treatments.

A veteran drug evaluator and a familiar presence on Capitol Hill, Woodcock was believed to be a leading candidate for the job. But resistance has grown over her role in the clearance of opioid drugs, as well as the more recent controversial approval of Biogen's Alzheimer's drug Aduhelm.

The uproar over the latter decision — and in particular, the close relationship between FDA staff and Biogen — prompted Woodcock herself to invite a government watchdog to review the process.

The vacancy this far into a presidential term is a departure from Presidents Barack Obama and Donald J. Trump, both of whom had nominated a commissioner by March of their first year in office. President George W. Bush, however, didn't have a permanent commissioner until November 2002, nearly two years into his presidency. 

The position can be a difficult one to fill, as it takes a specialized mix of medical, scientific, policy and public health expertise.

While Woodcock was regarded as a leading candidate based on her considerable experience as director of the Center for Drug Evaluation and Research, others have been discussed as potential candidates as well. Names included former FDA Principal Deputy Commissioner Amy Abernethy, who departed for Verily, Biotechnology Innovation Organization CEO Michelle McMurry-Heath, and Johns Hopkins scholar Joshua Sharfstein, a former top FDA official.

In an email, an FDA spokesperson referred questions about the decision to the White House. A White House spokesperson didn't respond to an email seeking comment.

In the absence of a permanent commissioner, Woodcock may be in charge of the agency when it faces a spate of important decisions on vaccines and therapeutics to combat the COVID-19 pandemic in coming weeks and months. Those include the formal approval of booster shots, converting emergency clearances for Pfizer's and Moderna's vaccines and Regeneron's antibody treatments to standard approvals, and decisions on inoculations for children.

Moreover, multiple oral antiviral drugs, seen as a critical potential weapon against the coronavirus, could be up for regulatory reviews if they succeed in clinical testing later this year. Positive results from Merck & Co. and others could force the agency to consider new emergency use authorizations.

Meanwhile, important non-pandemic issues continue as well, such as an ongoing safety review for a class of anti-inflammatory drugs known as JAK inhibitors. The agency is also preparing to renew its authorization to charge fees for drug reviews, a process that requires substantial changes to its policies.  

The current version of the law expires on Sept. 30, 2022, and the new five-year plan will come with new budget requests as well as a new set of FDA goals. The agency is looking to reinforce its cell and gene therapy division, for instance, while exploring how to better streamline clinical trials.

Signs that Woodcock might not gain necessary support in the Senate for confirmation emerged when a number of Democratic lawmakers questioned her role overseeing the agency's approvals of the opioid-based painkillers that fueled a drug abuse crisis in the U.S.

The question of her candidacy grew more complicated in early June, when the FDA controversially approved Aduhelm drug despite conflicting clinical trial evidence and opposition from the agency's advisers.

While Woodcock was not directly involved in that decision, she has defended it forcefully in news interviews and public appearances. To critics, the FDA's endorsement of Aduhelm recalled an earlier approval of a muscular dystrophy drug from Sarepta Therapeutics, which Woodcock supported over objections from other senior FDA officials.

Joe Manchin, the influential Democratic senator from West Virginia, cited the approval of Aduhelm, as well as the regulator's handling of the opioid crisis, in a June 17 letter to Biden describing why Woodcock "is not the right person to lead the FDA."

Pressure on Woodcock has only grown since, as reports have raised questions about the FDA's collaboration with Biogen on Aduhelm. On July 9, Woodcock asked the inspector general at the Department of Health and Human Services — the FDA's parent agency — to investigate contacts between representatives of Biogen and the FDA. 

Yet Woodcock has also won many allies over her decades of FDA service, most notably as the director of the Center for Drug Evaluation and Research. Better known as CDER, the office reviews and makes approval decisions on the majority of drugs on the U.S. market, excepting vaccines, cell and gene therapies and some blood products.

Woodcock was first named CDER director in 1994, with brief interludes from 2004 to 2007 and last year, when she took part in the Trump administration's coronavirus drug development effort. Over that time, Woodcock has been involved in approval of scores of drugs, many of which have helped people live longer or gain control over their disease symptoms.

But others have turned out to be harmful or otherwise controversial. Some, like the diabetes pill Avandia and the pain reliever Vioxx, were withdrawn from the market in major public health controversies. CDER's approval of many opioid-based painkillers, meanwhile, spurred opposition to her nomination, with a coalition of advocacy groups urging Health and Human Services Secretary Xavier Becerra to choose somebody else.

Woodcock has been supported by many former FDA commissioners, including both Republican appointees like Scott Gottlieb and Democratic ones like Margaret Hamburg, who has praised "her commitment to FDA's scientific mission and its career staff."

Woodcock's supporters have argued her leadership and experience could provide continuity after a trying year, during which the FDA was under a heavy workload and faced unprecedented political pressure to quickly deliver coronavirus vaccines, drugs and diagnostics.

"Many of the people, say in the medical products centers, are weary with all the work," Woodcock said at an event held by the Alliance for a Stronger FDA this spring. "It is more problematic in some areas than others, obviously, but I think they are very proud of what they have been able to accomplish and I am too." 

Woodcock is eligible to stay on as commissioner until November 15, or earlier if a new candidate is nominated, Bloomberg reported. Biden isn't expected to name a nominee in the immediate future, according to the report.