This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Targeted Anticancer Drugs and Immunosuppressants, Subject name: Pharmacology
Drug of choice for treatment of chronic myeloid leukemia is 
Select and explain. 
A. Imatinib, B. Cisplatin, C. Methotrexate, D. Tamoxifen
A: Imatinib
Answer: A: Imatinib 
Explanation: Imatinib - first line drug for chronic phase CML,in blast crisis and second line therapy for chronic phase CML that has progressed on prior IFN-a therapy Imatinib is also first line drug for metastatic c-kit positive GIST. Nilotinib, Bosutinib, Dasatinib - used in treatment of resistant CML Dasatinib is also used for treatment of Philadelphia chromosome positive ALL. Sunitinib-approved for the treatment of Advanced RCC and for the treatment of GIST after disease progression on or with intolerance to Imatinib. Methotrexate- DOC of choriocarcinoma Cisplatin - DOC- esophageal or gastric cancer Tamoxifen - DOC for ER positive breast cancer