Nilotinib and Imatinib Mesylate in Treating Patients With Early Chronic Phase Chronic Myelogenous Leukemia

DISEASE CHARACTERISTICS: * Cytologically and cytogenetically confirmed chronic myelogenous leukemia meeting the following criteria: * Early chronic phase disease (\< 6 months from diagnosis) * Philadelphia chromosome-positive disease * BCR-ABL-positive PATIENT CHARACTERISTICS: * WHO performance status 0-1 * ALT and AST = 2.5 times upper limit of normal (ULN) (5.0 times ULN if considered due to leukemia) * Alkaline phosphatase = 2.5 times ULN (unless considered due to leukemia) * Serum bilirubin = 1.5 times ULN * Serum creatinine = 1.5 times ULN * Serum amylase = 1.5 times ULN * Serum lipase = 1.5 times ULN * Normal serum levels of the following or correctable with supplements: * Potassium * Total calcium (corrected for serum albumin) * Magnesium * Phosphorus * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective barrier method contraception during study and for up to 3 months following completion of study treatment * No impaired cardiac function, including any of the following: * LVEF \< 45% by MUGA scan or echocardiogram * Uncontrolled congestive heart failure * Uncontrolled hypertension * Uncontrolled angina pectoris * Myocardial infarction within the past 12 months * No significant electric heart abnormalities, including any of the following: * History or active ventricular or atrial tachyarrhythmias * Congenital long QT syndrome and/or QTc \> 450 msec on screening ECG * No history of acute (within one year) or chronic pancreatitis * No impairment of gastrointestinal (GI) function or GI disease that may significantly alter the absorption of study drugs (e.g., ulcerative diseases, uncontrolled nausea, vomiting, diarrhea, malabsorption syndrome, or small bowel resection) * No acute or chronic liver or renal disease considered unrelated to leukemia * No known diagnosis of HIV infection * No other concurrent severe and/or uncontrolled medical conditions (e.g., uncontrolled diabetes, active or uncontrolled infection) that could cause unacceptable safety risks or compromise compliance with the protocol * No other primary malignancy that is currently clinically significant or requires active intervention PRIOR CONCURRENT THERAPY: * More than 2 weeks since prior major surgery and recovered * More than 30 days since prior imatinib mesylate, with a washout period of ≥ 7 days * More than 4 weeks since prior investigational drug * No prior hematopoietic stem cell transplantation * No concurrent therapeutic coumarin derivates (i.e., warfarin, acenocoumarol, phenprocoumon) * No concurrent medications that would prolong the QT interval * No concurrent chemotherapy, investigational agents, radiotherapy, or biologic therapy * Prior treatment with hydroxyurea or anagrelide allowed