A 78-year-old man repos anorexia, fatigue, and generally feeling unwell. On examination he has a large spleen, appears pale, and the rest of the examination is normal. His blood count is abnormal; the WBC is 46000/ml with increased mature granulocytes, hemoglobin 9.0 g/dL, and platelets 450,000/mL. Fuher investigations reveal BCR-ABL transcripts. T315I mutation is also seen. What is the drug of choice for this condition?