Mateon Therapeutics, Inc., formerly OXiGENE, Inc., is a biopharmaceutical company. The Company is focused on the development of vascular disrupting agents (VDAs) for the treatment of cancer. The Company is engaged in developing two clinical stage investigational drugs: VDAs-CA4P and OXi4503. Its lead compound is CA4P, which is also known as combretastatin A4-phosphate, fosbretabulin tromethamine, fosbretabulin and ZYBRESTAT. VDAs selectively targets the vasculature of cancer tumors and obstructs a tumor's blood supply without disrupting the blood supply to normal tissues. VDAs are in a class of drugs called vascular targeted therapies (VTTs), which also includes anti-angiogenic agents (AAs). CA4P is a reversible tubulin binding agent that selectively targets the endothelial cells that make up the blood vessel walls in solid tumors. The Company is pursuing the development of a product candidate, OXi4503, which is a dual-mechanism VDA.