U.S. regulators are stepping up scrutiny of therapies that were granted an accelerated approval to treat cancers on the basis of surrogate endpoints but have failed to show clinical or survival benefits upon more extensive testing.
At issue are a number of cancer indications for immunotherapies. Four have already been withdrawn (voluntarily by the manufacturer), and six more will be reviewed at an upcoming meeting.
In recent years, the US Food and Drug Administration has granted accelerated approvals to oncology medicines on the basis of evidence that suggests a benefit for patients. Examples of such evidence relate to response rates and estimates of tumor shrinkage. But these approvals are granted on the condition that the manufacturer conducts larger clinical trials that show clinical benefit, including benefit in overall survival.
Richard Pazdur, MD, director of the FDA’s Oncology Center of Excellence, has argued that the point of these conditional approvals is to find acceptable surrogate markers to allow people with “desperate illnesses” to have access to potentially helpful drugs while work continues to determine the drug’s actual benefit to patients.
Oncologists are now questioning whether the FDA has become too lenient in its approach, Daniel A. Goldstein, MD, a senior physician in medical oncology and internal medicine at the Rabin Medical Center, Petah Tikva, Israel, told this news organization.
“The main two things you want from a cancer drug is to live longer and live a higher quality of life,” said Goldstein. “But these endpoints that they’ve been using over the past few years are not really giving us confidence that these drugs are actually going to help to live longer or better.”
Dr. Pazdur said the FDA will consider withdrawing its accelerated approvals when results of further studies do not confirm expected benefit for patients.
“This is like the pendulum has swung as far as it was going to swing and now is on the backswing,” said Dr. Goldstein, also of the department of health policy and management at the University of North Carolina at Chapel Hill. “You could call this a watershed moment.”
Although there’s near universal interest in allowing people with advanced cancer access to promising medicines, there’s also rising concern about exposing patients needlessly to costly drugs with potentially tough side effects. That may prompt a shift in the standards U.S. regulators apply to cancer medicines, Dr. Goldstein said.
Indications withdrawn and under review
In a meeting scheduled for April 27-29, the FDA’s Oncologic Drugs Advisory Committee will review indications granted through the accelerated approval process for three immunotherapies: pembrolizumab (Keytruda), atezolizumab (Tecentriq), and nivolumab (Opdivo).
It is part of an industry-wide evaluation of accelerated approvals for cancer indications in which confirmatory trials did not confirm clinical benefit, the FDA noted.
The process has already led to voluntary withdrawals of four cancer indications by the manufacturers, including one indication each for pembrolizumab, atezolizumab, and nivolumab, and one for durvalumab (Imfinzi).
All of these immunotherapies are approved for numerous cancer indications, and they all remain on the market. It is only the U.S. approvals for particular cancer indications that have been withdrawn.
In the past, olaratumab (Lartruvo) was withdrawn from the market altogether. The FDA granted accelerated approval of the drug for soft tissue sarcoma, but clinical benefit was not confirmed in a phase 3 trial.