Landmark clinical studies of new drugs developed to target specific forms of cancer were reported in 2001. Herceptin, a monoclonal antibody against the Her2/neu receptor tyrosine kinase, prolonged the survival of women with Her-2/neu positive metastatic breast cancer, when combined with chemotherapy. STI-571, a small molecule inhibitor of the Bcr-Abl, c-kit and platelet derived growth factor receptor tyrosine kinases, produced dramatic clinical responses in patients with Bcr-Abl positive chronic myeloid leukemia and c-kit positive gastrointestinal stromal tumors. These examples have galvanized the cancer research community to extend kinase-inhibitor therapy to other cancers.