Peregrine Pharmaceuticals announced the issuance of U.S. Patent No. 6,451,312 covering new Vascular Targeting Agent (VTA) therapeutics. Peregrine's VTA technology is based on targeting agents that specifically target tumor blood vessels. The targeting agents can be attached to therapeutic agents that destroy or occlude tumor blood vessels, leading to an avalanche of tumor cell death without harming the vasculature of normal tissue.

The new patent extends the company's broad patent coverage of VTA compositions and treatment methods by providing a unique "targeting agent-therapeutic agent" combination. The targeting agent is the ligand VEGF (vascular endothelial cell growth factor) and the therapeutic agent is a cytotoxic factor termed gelonin. The VEGF-gelonin constructs covered by the new patent complement Peregrine's other VTAs, which use a range of antibody- and ligand-based targeting agents to deliver therapeutic agents such as other cytotoxins, coagulant proteins and radionuclides, into the heart of solid tumors.

The VEGF-gelonin constructs protected by U.S. Patent No. 6,451,312 specifically targets tumor blood vessels and pre-clinical studies in animal models have shown impressive anti-tumor effects. In particular, a preclinical study published in June in the Proceedings of the National Academy of Sciences, involved administering VEGF121/rGelonin (VEGF/rGel) in mice injected with human melanoma and human prostate cancer cells. Researchers found that tumors in mice treated with VEGF/rGel had been reduced by up to 84 percent compared to tumors in untreated mice. Furthermore, VEGF/rGel selectively destroyed blood vessels supplying human solid tumors without harming the vasculature of normal tissue.

"This patent is particularly designed to protect the ligand-based therapeutic conjugates licensed to SuperGen Inc," said Edward J. Legere, Peregrine's president and CEO. "Our strong intellectual property position in the VTA field allows us to develop VTA based therapeutics and diagnostics through multiple licenses and joint ventures and also in-house. Peregrine has seen significant interest in licensing its VTA platform. A number of VTA compounds are being evaluated by companies for their potential as anticancer agents. Peregrine is very active in its efforts to license various uses of the VTA platform. We look forward to future collaborations with other companies," Legere added.