A drug used to treat glioblastoma (a type of brain cancer) and certain types of colorectal cancer, lung cancer, and kidney cancer. It is also being studied in the treatment of other types of cancer. Avastin binds to a protein called vascular endothelial growth factor (VEGF). This may prevent the growth of new blood vessels that tumors need to grow. It is a type of antiangiogenesis agent and a type of monoclonal antibody. Also called bevacizumab.