This study will assess the pharmacokinetics of imatinib in pediatric patients ages 1 to <4 years of age to help develop dosing regimens

Inclusion Criteria:

1. Patients must be 1 to less than 4 years of age at study entry

2. Written informed consent must be signed by the patient's parent or legal guardian.

3. Patients must have the diagnosis of CML or Ph+ ALL

4. Lansky score must be ≥ 50 (Table7-2)

5. Patient must have adequate end organ function as defined by

   • Total bilirubin < 1.5 x ULN
   • SGPT (ALT) and SGOT (AST) < 2.5 x UNL
   • Creatinine < 1.5 x ULN

Exclusion Criteria:

1. Patients who have received drugs a) known to be metabolized by CYP3A4 or 3A5, b) are CYP inhibitors and inducers, within 2 weeks prior to Visit 2 (except for imatinib)
2. Patients who previously received radiotherapy to ≥ 25% of the bone marrow, with the exception of patients who received total body radiation as part of a preparatory regimen for hematopoetic stem cell transplant (HSCT)
3. Patients receiving antibacterial and antipyretic medication to treat active infection
4. Patients with International normalized ratio (INR) or partial thromboplastin time (PTT) > 1.5 x ULN, with the exception of patients on treatment with oral anticoagulants
5. Patients whose parents or legal guardians, in the opinion of the Investigator, were unlikely to comply with the protocol or safety monitoring requirements

Other protocol-defined inclusion/exclusion criteria may apply