Peregrine Pharmaceuticals, Inc reported the issuance of a US patent with broad claims covering vascular imaging applications for phosphatidylserine (PS)-targeting antibodies. The patent represents the first broad coverage of imaging claims under Peregrine's PS-targeting platform, which includes Peregrine's lead antibody bavituximab. PS is a phospholipid that becomes exposed on the surface of tumour blood vessel cells. Since PS is typically not exposed on the surface of normal tissues, it represents a unique target for the vascular imaging of tumours and tumour metastases in patients with cancer.

"PS-targeting antibodies such as bavituximab preferentially bind to tumour blood vessels, which makes them ideal vehicles for imaging the tumour vasculature," said Dr Philip Thorpe, professor of pharmacology at UT Southwestern Medical Center and a scientific advisor to Peregrine. "Last year we published data from preclinical imaging studies confirming bavituximab's high specificity for targeting tumour blood vessels with little or no localization to normal tissue. Bavituximab's ability to achieve unusually clear images of tumours in living animals in these studies supports the concept that PS-targeting antibodies may be useful for the non-invasive detection of tumours and their metastases in cancer patients."

The new patent claims methods for imaging solid tumours using PS-targeting antibodies coupled to a variety of imaging agents.

"Issuance of this broad vascular imaging patent expands the breadth of our intellectual property around our PS-targeting platform," said Steven W King, president and CEO of Peregrine. "This patent protects expanded use of bavituximab and other PS-targeting antibodies to track disease and treatment status in cancer patients. The growing patent estate around our PS-targeting technology provides us with new options and applications for leveraging our PS-targeting antibodies."

Bavituximab, Peregrine's most advanced PS-targeting antibody, is currently being tested in combination with chemotherapy in one phase-II trial in advanced lung cancer and two phase-II trials in advanced breast cancer. Interim data from these studies has been promising.

US Patent #7,550,141, which was issued on June 23, 2009, was granted to the University of Texas System and is exclusively licensed to Peregrine Pharmaceuticals.

The rapid and disorganized growth that is the hallmark of cancer results in the exposure of the lipid phosphatidylserine (PS) on the surface of tumour blood vessels.

Peregrine Pharma is a biopharmaceutical company with a portfolio of innovative monoclonal antibodies in clinical trials for the treatment of cancer and serious viral infections.