Effect of Imatinib Mesylate and the Pharmacokinetics of Acetaminophen/Paracetamol in Patients With Newly Diagnosed, Previously Untreated Chronic Myeloid Leukemia in Chronic Phase (CML-CP)

Inclusion criteria: * Ability to provide written informed consent prior to participation to the study. * Male or female patients ≥ 18 and ≤ 75 years of age * Patients with CML-CP within 6 months of diagnosis (date of initial diagnosis is the date of first cytogenetic analysis). FISH analysis will not be accepted. * Diagnosis of CML in chronic phase with cytogenetic confirmation of Philadelphia chromosome of (9;22) translocations and presence of Bcr-Abl * Documented chronic phase CML as defined by: * \< 15% blasts in peripheral blood and bone marrow * \< 30% blasts plus promyelocytes in peripheral blood and bone marrow * \< 20% basophils in the peripheral blood * ≥ 100 x 109/L (≥ 100,000 /mm3) platelets * No evidence of extramedullary leukemic involvement, with the exception of hepatosplenomegaly * Adequate end organ function as defined by: * total bilirubin \< 1.5 x ULN * SGOT and SGPT \< 2.5 x UNL * creatinine \< 1.5 x ULN * Female patients of childbearing potential must have a negative serum pregnancy test within 7 days before initiation of study drug Exclusion criteria: * Patients in late chronic phase, accelerated phase, or blastic phase are excluded * Patients who have received other investigational agents * Patients who received imatinib for any duration prior to study entry * Patient received any treatment for CML prior to study entry for longer than 2 weeks with the exception of hydroxyurea and/or anagrelide * Patients with another primary malignancy except if the other primary malignancy is neither currently clinically significant or requiring active intervention * Patients who are: * pregnant * breast feeding * of childbearing potential without a negative pregnancy test prior to baseline * male or female of childbearing potential unwilling to use barrier contraceptive precautions throughout the trial * Post-menopausal women must be amenorrheic for at least 12 months to be considered of non-childbearing potential * Patient with a severe or uncontrolled medical condition (i.e., uncontrolled diabetes, chronic renal disease) * Patient previously received radiotherapy to ≥ 25% of the bone marrow * Patient had major surgery within 4 weeks prior to study entry, or who have not recovered from prior major surgery * Patients with an ECOG Performance Status Score ≥ 3 * Patients with International normalized ratio (INR) or partial thromboplastin time (PTT) \> 1.5 x IULN, with the exception of patients on treatment with oral anticoagulant * Patients with known positivity for human immunodeficiency virus (HIV) * baseline testing for HIV is not required * Patients with any significant history of non-compliance to medical regimens or with inability to grant a reliable informed consent * Patients with identified sibling donors where allogeneic bone marrow transplant is elected as first line treatment * Patients who are chronic users of acetaminophen or medications containing acetaminophen. * Patients who received acetaminophen or medications containing acetaminophen within 72 hours prior to study entry. Other protocol-defined inclusion/exclusion criteria may apply