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Cancer drugs can get rushed to market based on encouraging preliminary studies. Then when more careful follow-up studies are done, those drugs often don't show clear benefits. That's according to new research. NPR science correspondent Richard Harris has details.
RICHARD HARRIS, BYLINE: The Food and Drug Administration recently looked back on 93 cancer drugs it had approved through its accelerated process and noted that only five had been withdrawn from the market as a result of the follow-up studies. Oncologist Bishal Gyawali and colleagues at Harvard looked at the fate of the rest of those drugs.
BISHAL GYAWALI: Of those 93 drugs, only 19 have saw an improvement in overall survival, so that's 20%.
HARRIS: Overall survival is the most important outcome because most patients expect a cancer drug to help them live longer. Gyawali, who's now at Queen's University in Ontario, says, take, for example, a drug to treat glioblastoma, a deadly brain cancer. It was approved based on preliminary data, and the FDA required a confirmatory trial.
GYAWALI: And the confirmatory trial, in fact, conclusively shows that the drug does not improve overall survival.
HARRIS: Researchers also considered whether the drug improved a patient's quality of life. Gyawali says it didn't do that either.
GYAWALI: It does not improve overall survival. It does not improve quality of life. That was the most baffling thing that - I find it very difficult to understand.
HARRIS: Despite these apparent failures, the drug remains on the market as an approved treatment for glioblastoma. The FDA has not said why, and Gyawali says that's a problem.
GYAWALI: The reason for giving these approvals should be transparent.
HARRIS: What of the other drugs granted accelerated approval that are still on the market? Some are still being studied. For others, the confirmatory tests didn't look at survival or quality of life but used the exact same endpoint that earned it preliminary approval. It was a so-called surrogate endpoint, such as temporary tumor shrinkage. If that wasn't good enough for approval to begin with, Gyawali asks...
GYAWALI: Then how can we use the same surrogate endpoint and say that they have clinical benefit in a confirmatory trial?
HARRIS: The study is published in JAMA Internal Medicine alongside a second study that probed the same issue. Emerson Chen, who's an oncology fellow at Oregon Health and Science University, found that some confirmatory studies don't use the gold standard study design - a randomized, controlled trial.
EMERSON CHEN: If we really put in the investment in it, we would be able to do randomized, controlled trials and really have more definitive information about the survival in the patient-reported outcomes.
HARRIS: Randomized trials can add a year or more to the drug-testing process. And both patients and drug companies are eager for quick drug approval. Dr. Richard Schilsky, chief medical officer of the American Society for Clinical Oncology, says the new studies highlight an important issue. But he doesn't see the results as an indictment of the approval process.
RICHARD SCHILSKY: The challenge is making sweeping generalizations when these regulatory decisions have to be made on a case-by-case basis and in a particular context.
HARRIS: But he agrees that the FDA should be more transparent about its decisions. Richard Harris, NPR News.
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