Protein levels could predict if bowel cancer patients will benefit from Avastin

Oct. 25, 2012

Comparing levels of specific proteins that the drug Avastin targets could identify patients with advanced bowel cancer who will benefit from the treatment, according to research published in Clinical Cancer Research. Avastin, or bevacizumab, has been shown to increase survival from bowel cancer in 10 to 15 percent of patients, but it has been impossible to predict who will benefit.

Avastin works by targeting and blocking the VEGF-A protein, two major forms of which are VEGF165 and VEGF165b. VEGF165 helps cancers to grow new blood vessels, so they can get food and oxygen from the blood. Its sister protein, VEGF165b, has the opposite effect and acts as a brake on this growth. Scientists at the University of Bristol in England looked at the effect Avastin had on patients with different levels of VEGF165b and compared that with patients who were not given the drug at all. Those with low levels of VEGF165b survived three months longer without the disease progressing compared to patients not treated with Avastin. But patients with higher levels of the protein saw no benefit from Avastin and survived no longer than those who were not given the drug. Avastin blocks both forms of VEGF-A, so in patients with lower levels of VEGF165b more Avastin may be available to block the blood vessel promoting protein VEGF165, eventually starving the cancer.

David Bates, PhD, lead researcher from the University of Bristol’s School of Physiology and Pharmacology, says, “We now need to look at cancer samples from a larger group of patients about to start taking Avastin and determine if the amount of VEGF165b can accurately identify those patients who will benefit.” Read more in a Yahoo article.