STAT Report : The need for speed and safety: A primer on the FDA’s drug approval pathways

By Kerry Dooley Young, March 2022



Only about 14% of drugs that advance as far as clinical trials eventually win FDA approval, researchers from the Massachusetts Institute of Technology reported in a 2018 paper in the journal Biostatistics. That’s actually an improvement from previous estimates that put the failure rate at about 90%.

Productive researchers can spend their careers at pharmaceutical and biotech companies without seeing any of their work result in a marketed product.

“I’ve been doing this for 27 years, and I have never once put a drug into a pharmacy,” Derek Lowe, a medicinal chemist and noted blogger, said in a 2016 interview with STAT.



In cases of fatal or serious illnesses such as cancer, the FDA allows sales of drugs through its accelerated-approval program based on promising results that only suggest a significant benefit for patients.

As of December 2021, the FDA had granted 278 accelerated approvals. But many of these were granted to the same medicines for multiple uses, or indications — so in total, only about 160 different medicines have won accelerated approval. Sometimes the designations pertain to different uses for the same drug.

An extreme example is Merck’s Keytruda cancer medicine. The FDA has granted more than 30 accelerated approvals of Keytruda, covering its use in more than a dozen forms of cancer. Keytruda also serves as a good example of why the accelerated approval process has been used so often for cancer medicines — and why there are growing concerns about this speedy pathway.


Since March 2021, Merck has voluntarily withdrawn two additional approvals granted for Keytruda.

The Keytruda withdrawals follow a public crackdown by Pazdur, the FDA’s top regulator of cancer drugs, on what he terms “dangling” accelerated approvals — cases where companies have not moved to seek the withdrawal of an accelerated approval after confirmatory trials fail.


Pazdur, who joined FDA in 1999, has been a champion of using accelerated approval, but he is insistent that the industry use the pathway the way it was intended. He’s been wrestling for years with drugmakers about standards for evidence, while also working to speed drug approvals.

“We have a litany of [drug companies] that come in and pose the question to us… ‘What is the lowest response rate that you will take? What is the fewest number of patients that you will take?’” Pazdur said during an FDA advisory committee meeting in 2004.

That’s not what the pathway is for, he made clear. “It wasn’t a license to do less, less, less, and less.”



Expect intense political clashes in the months ahead as Congress works on a major new FDA law.


Under President Biden’s new FDA Commissioner, Califf, the agency has asked Congress to give it more tools to compel drugmakers to complete research promised after accelerated approvals. This includes a request to make companies demonstrate that they have adequate plans for confirmatory studies before winning accelerated approvals.

These kinds of steps are needed to restore the public trust in the FDA, said Diana Zuckerman, president of the National Center for Health Research, which closely monitors the agency.


“Califf will find it impossible to restore the FDA’s reputation if he focuses primarily on the need for faster approvals and more flexible approval standards,” Zuckerman told STAT.


“The commissioner needs to directly address the Aduhelm disaster, because the FDA leadership responsible for that decision are still in positions of power in the agency.”


The entire 30 page report is available from Stat here.