A preclinical study has supported the specific tumour-targeting properties of the anti-phosphatidylserine (anti-PS) antibody platform in the treatment of prostate cancer.
The drug, being developed by Peregrine Pharmaceuticals, has the chemical name bavituximab, and is currently in Phase II cancer trials in combination with chemotherapy.
The study, published in Clinical Cancer Research, demonstrates that in a model of prostate cancer, bavituximab’s phosphatidylserine target is specifically exposed in tumours, but not in normal tissues.
When labelled with a radioisotope, bavituximab preferentially targeted the tumour blood vessels, strongly localising to the tumours rather than normal organs. The study was conducted by Dr Philip Thorpe and his colleagues at University of Texas (UT) Southwestern Medical Center, US. It is the latest in a series of preclinical studies that have confirmed important elements of the mechanism of action of bavituximab.
“These results confirming the high specificity of bavituximab to target tumour blood vessels with little or no localisation to normal tissues support the good safety profile and encouraging signs of anti-tumour activity seen to date with bavituximab,” said Dr Thorpe, professor of pharmacology at UT Southwestern and a member of Peregrine’s Scientific Resource Board.
“Bavituximab’s ability to achieve unusually clear images of tumours in living animals also suggests that it might have utility for the non-invasive imaging of tumours in cancer patients. Although the study was conducted in rats bearing prostate tumours, we expect that the observations will extend to other solid tumour types as well.”
Bavituximab is a monoclonal antibody that binds to a phospholipid called phosphatidylserine that is usually located inside normal cells, but which becomes exposed on the outside of the cells that line the blood vessels of tumours, creating a specific target for anti-cancer treatments. Bavituximab is believed to help mobilise the body’s immune system to destroy the blood vessels needed for tumour growth and spread.