A substance being studied in the treatment of many types of cancer. MK-0646 binds to a protein called insulin-like growth factor receptor (IGFR) on the surface of cells. This may prevent the cells from growing when IGF is present. It may also kill cancer cells. MK-0646 is a type of monoclonal antibody. Also called anti-IGF1R recombinant monoclonal antibody MK-0646.