Cancer drugs approved on basis of trials with surrogate end points fail to improve survival

The US drugs regulator may be approving costly and toxic cancer drugs that fail to live up to expectations and do not improve survival rates, according to research published in JAMA Internal Medicine
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on 19 October 2015.

Researchers from the US National Cancer Institute and the Knight Cancer Center at Oregon Health and Sciences University analysed overall survival data for cancer drugs approved by the Food and Drug Administration (FDA) between January 2008 and December 2012 where the approvals had been based on trials reporting a surrogate end point, such as a response rate or progression-free survival.

The study was prompted by criticism from the US government accountability office in 2009 that the FDA had failed to enforce post-marketing studies for surrogate approvals.

The researchers discovered 54 cancer drugs given a marketing authorisation in the five-year period analysed, of which 36 (67%) approvals were based on trials with a surrogate end point. A literature review that looked at evidence for the drugs’ effects on survival revealed that five drugs had improved overall survival; 18 failed to improve overall survival and 13 continue to have unknown survival rates.

“Our results show that most cancer drug approvals have not been shown or do not improve clinically relevant end points,” say the researchers.

Since 2008, the FDA has approved a higher percentage of drugs than previously, the researchers point out. “Cancer drugs are approved on the basis of surrogates that have poor correlations with overall survival,” they conclude. “Enforcement of post marketing studies is therefore of critical importance.”