Imatinib is an example of a new group of drugs being developed using the principle of molecular targeting. Imatinib is able to kill the cancer cells and not the body's healthy cells. Imatinib mesylate is indicated for the treatment of patients with Kit (CD117)-positive unresectable and/or metastatic malignant gastrointestinal stromal tumors and patients with Philadelphia chromosome-positive chronic myeloid leukemia in blast crisis, accelerated phase, or in chronic phase after failure of interferon-alfa.