Less Than 50% of Accelerated Approvals Show Clinical Benefit

SAN DIEGO — Fewer than half of the cancer drugs approved under the US Food and Drug Administration’s (FDA’s) accelerated approval pathway between 2013 and 2017 have been shown to improve overall survival or quality of life, despite being on the US market for more than 5 years, according to a new study. 

Under the program, drugs are approved for marketing if they show benefit in surrogate markers thought to indicate efficacy. Progression-free survival, tumor response, and duration of response are the most used surrogate markers for accelerated approvals of cancer drugs. These are based largely on imaging studies that show either a stop in growth in the case of progression-free survival or tumor shrinkage in the case of tumor response. 

Following accelerated approvals, companies are then supposed to show actual clinical benefit in confirmatory trials.

The problem with relying on surrogate markers for drug approvals is that they don’t always correlate with longer survival or improved quality of life, said Edward Cliff, MBBS, who presented the findings at the American Association for Cancer Research 2024 annual meeting (abstract 918). The study was also published in JAMA to coincide with the meeting presentation.

In some cancers, these markers work well, but in others they don’t, said Cliff, a hematology trainee at Brigham and Women’s Hospital, Boston, when the work was conducted, and now a hematology fellow at the Peter MacCallum Cancer Centre in Melbourne, Australia.

To determine whether cancer drugs granted accelerated approval ultimately show an overall survival or quality of life benefit, researchers reviewed 46 cancer drugs granted accelerated approvals between 2013 and 2017. Twenty (43%) were granted full approval after demonstrating survival or quality-of-life benefits. 

Nine, however, were converted to full approvals on the basis of surrogate markers. These include a full approval for pembrolizumab in previously treated recurrent or refractory head and neck squamous cell carcinoma and a full approval for nivolumab for refractory locally advanced or metastatic urothelial carcinoma, both based on tumor response rate and duration of response.

Of the remaining 17 drugs evaluated in the trial, 10 have been withdrawn and seven do not yet have confirmatory trial results. 

The reliance on surrogate markers means that these drugs are used for treatment, covered by insurance, and added to guidelines — all without solid evidence of real-world clinical benefit, said Cliff. 

However, the goal should not be to do away with the accelerated approval process, because it sometimes does deliver powerful agents to patients quickly. Instead, Cliff told Medscape Medical News, the system needs to be improved so that “we keep the speed while getting certainty around clinical benefits” with robust and timely confirmatory trials. 

In the meantime, “clinicians should communicate with patients about any residual uncertainty of clinical benefit when they offer novel therapies,” Cliff explained. “It’s important for them to have the information.”

There has been some progress on the issue. In December 2022, the US Congress passed the Food and Drug Administration Omnibus Reform Act. Among other things, the Act requires companies to have confirmation trials underway as a condition for accelerated approval, and to provide regular reports on their progress. The Act also expedites the withdrawal process for drugs that don’t show a benefit. 

The Act has been put to the test twice recently. In February, FDA used the expedited process to remove the multiple myeloma drug melphalan flufenamide from the market. Melphalan flufenamide hadn’t been sold in the US for quite some time, so the process wasn’t contentious. 

In March, Regeneron announced that accelerated approval for the follicular and diffuse B cell lymphoma drug odronextamab has been delayed pending enrollment in a confirmatory trial. 

“There have been some promising steps,” Cliff said, but much work needs to be done. 

Study moderator Shivaani Kummar, MD, agreed, noting that “the data is showing that the confirmatory trials aren’t happening at the pace which they should.” 

But the solution is not to curtail approvals; it’s to make sure that accelerated approval commitments are met, said Kummar.

Still, “as a practicing oncologist, I welcome the accelerated pathway,” Kummar, a medical oncologist/hematologist at Oregon Health & Science University, Portland, told Medscape Medical News. “I want the availability to my patients.” 

Having drugs approved on the basis of surrogate markers doesn’t necessarily mean patients that are getting ineffective therapies, Kummar noted. For instance, if an agent just shrinks the tumor, it can sometimes still be “a huge clinical benefit because it can take the symptoms away.” 

As for prescribing drugs based on accelerated approvals, she said she tells her patients that trials have been promising, but we don’t know what the long-term effects are. She and her patient then make a decision together. 

The study was funded by Arnold Ventures. Kummar reported support from several companies, including Bayer, Gilead, and others. Cliff had no disclosures. 

M. Alexander Otto is a physician assistant with a master’s degree in medical science and a journalism degree from Newhouse. He is an award-winning medical journalist who worked for several major news outlets before joining Medscape. Alex is also an MIT Knight Science Journalism fellow. Email: [email protected]

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