A substance being studied in the treatment of glioblastoma (a type of brain tumor) that has come back. It binds to receptors for a protein called platelet-derived growth factor (PDGF). This keeps PDGF from binding to the cells. This may stop the growth of cancer cells and blood vessels that have the receptors for PDGF. It is a type of monoclonal antibody. Also called anti-PDGFR alpha monoclonal antibody IMC-3G3 and IMC-3G3.