NPR logo Evidence Builds On Fatal Side Effects From Cancer Drug Avastin


Evidence Builds On Fatal Side Effects From Cancer Drug Avastin

Richard Morgenstein/Genetech
A vial of Gnenetech's Avastin.
Richard Morgenstein/Genetech

An analysis has found that patients who take the best-selling cancer drug Avastin are almost 50 percent more likely to suffer fatal side effects than those on chemotherapy alone.

Researchers at Stony Brook University Medical Center in New York came to that conclusion after pooling data from 16 published studies. Their report appears in the current Journal of the American Medical Association.

To be sure, the absolute risk of death is not high — 148 fatal side effects among 5,589 Avastin patients, or 2.5 percent. Among the chemotherapy group, the risk of dying from treatment was 1.5 percent.

Still, study authors say doctors and patients should be aware of the risk, and patients on Avastin should be monitored carefully for events such as bleeding, infections, and strokes.

Avastin's maker Genentech was not exactly thrilled with the new analysis.

"The analysis contains cancer types for which Avastin is not used," Charlotte Arnold, a Genentech spokeswoman, told Shots. Cancers for which Avastin is approved – advanced colorectal, renal and breast – had similar fatal side effects between Avastin and control groups, she added.

Still, even without the latest questions, Avastin — the world's leading cancer drug with an estimated $6.5 billion in sales — is a perplexing success.

It does hold some advanced cancers at bay, which many doctors and patients say justifies the intravenous drug's $50,000-a-year cost.

But it's been disappointing too. In December, the Food and Drug Administration moved to rescind Avastin's approval for advanced breast cancer, noting the lack of evidence the drug increases survival. Genentech, its maker, is appealing that decision.

In general, notes Dr. Daniel Hayes of the University of Michigan, it's been hard to show that Avastin actually extends patients' lives.

Hayes wonders in a JAMA editorial if Avastin should be considered a cancer boon – or a bust.

"Why [hasn't Avastin] been more successful in improving overall survival?" Hayes asks.

The answer may be – as it is with many new cancer drugs – that Avastin really benefits some patients, but not others. But so far, even though Avastin has been studied in tens of thousands of patients, no one knows who exactly benefits, or for how long.

Genentech would also like to figure out who benefits from the medicine. Patients, doctors and those who pay the hefty Avastin tab should hope the company succeeds.