How cancer drugs can damage the kidneys

The cancer drug Avastin (bevacizumab) can damage the kidneys. It was the first of a family of drugs designed to starve cancers by cutting off their blood supply, blocking vascular endothelial growth factor (VEGF), which drives the growth of blood vessels.

One side effect of Avastin is protein in the urine, a sign of kidney damage, caused by blocked growth of the tiny blood vessels in the kidneys. Studies put the rate of kidney effects at 21–64%, with serious damage in 1–2% of users. Protein in the urine doesn't necessarily mean the drug must be stopped. Avastin was one of the first drugs of its kind approved by the FDA, for lung and colon cancer.

A new study published in the New England Journal of Medicine says that doctors using Avastin and other VEGF inhibitors should watch for side effects anywhere in the body, as VEGF supports many normal tissues as well as blood vessels. In mice, the drug damaged the VEGF-producing cells that control the passage of fluid into the brain's ventricles, the process that forms cerebrospinal fluid.

This matters because some doctors use the drug to treat macular degeneration, a cause of failing vision in older people. Brain problems (encephalopathy) were seen in a few patients on long-term Avastin, so care is needed, as all healthy tissues may be affected.