Federal health scientists said Friday that follow-up studies of a Roche breast cancer drug show it failed to slow tumor growth or extend patient lives, opening the door for a potential withdrawal in that indication.
The Food and Drug Administration approved Roche's blockbuster Avastin in 2008 based on early-stage trials showing it shrank tumors caused by breast cancer. The decision was controversial because drugs for cancer patients who have never been treated before must usually show evidence they extend lives.
Avastin's so-called "accelerated approval" was based on the condition that later studies would show a survival benefit.
But in briefing documents posted online, FDA reviewers said two follow-up studies recently submitted by Roche failed to show that Avastin significantly extended lives compared to chemotherapy alone.
Additionally, the FDA said more recent data did not confirm the tumor shrinkage seen in earlier studies.
Patients taking Avastin showed significantly more side effects, including high blood pressure, fatigue and abnormal white blood cell levels.
On Tuesday the FDA will ask a panel of outside cancer experts to review the evidence on Avastin. The panel's recommendations are not binding, but the FDA usually follows their guidance.
The FDA has the option to remove drug's approval for breast cancer.
Avastin is also approved for colon, lung, kidney and brain cancer. The drug was Roche's top-selling cancer treatment last year with global sales of $5.9 billion.
Roche is headquartered in Basel, Switzerland, and its biotech unit Genentech is based in South San Francisco.
Avastin was the first drug to fight cancer by stopping nutrients from reaching tumors. Such "targeted therapies" were thought to hold promise for eliminating chemotherapy, but the two approaches are now used in combination.
Since 1992, the FDA has granted accelerated approval to drugs based on so-called surrogate endpoints, or initial measures that suggest the drug will make real improvements in patient health. For cancer drugs, tumor shrinkage is considered a predictor of increased survival.
Drugmakers favor the program because it helps them get products to market sooner.
But the program has not escaped criticism from government watchdogs.
Last fall the Government Accountability Office issued a report saying the FDA should do more to track whether drugs approved based on preliminary results actually have live up to their promise.
According to the GAO, the FDA has never once pulled a drug off the market due to missing or unimpressive follow-up data.