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

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 around 10 to 15 per cent 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 - all cancers need a blood supply to be able to survive and grow. Its sister protein, VEGF165b, has the opposite effect and acts as a brake on this growth.

Cancer Research UK-funded scientists at the University of Bristol looked at the effect Avastin had on patients with different levels of VEGF165b and compared this 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 as those who were not given the drug.