Analysis of the first 10 patients did not show anyt trend toward differences in PK profiles between imatinib vs no imatinib groups.

This study is characterizing the pharmacokinetics of vincristine using two different cohorts of patients. The first cohort includes patients with acute lymphoblastic leukemia (ALL) that are Bcr-Abl positive. This cohort of patients will receive vincristine along with imatinib in the induction chemotherapy regimen. The second cohort includes patients with ALL that are Bcr-Abl negative. This cohort of patients will receive vincristine without imatinib in the induction chemotherapy regimen. This study involves blood draws beginning on day 7 of the treatment protocol and these samples will be analyzed for pharmacokinetic parameters.

Imatinib and vincristine are both metabolized by the hepatic CYP 450 enzyme system. Imatinib is an inhibitor of the system and co-administration of imatinib and vincristine has the potential to increase the blood level of vincristine. This could explain the increased level of neurotoxicity that is currently being seen with the co-administration of these two agents in the treatment of Bcr-Abl positive ALL.

Inclusion Criteria:

• Age >/= 18 years
• New Diagnosis of Bcr-Abl positive ALL or Bcr-Abl negative ALL
• Receiving induction chemotherapy with the standard Princess Margaret Hospital modified DFCI protocol
• Will have a functioning central venous access catheter in-situ
• Agreeing to participate in the study and sign the informed consent form

Exclusion Criteria:

• Concomitant use of other agents that inhibit hepatic cytochrome CYP3A4, as these drugs may alter vincristine and imatinib levels
• Elevated liver function tests: bilirubin >1.5xULN or AST/ALT >2.5xULN, or documented history of chronic liver disease.

Patients with Acute Lymphoblastic Leukemia will be selected from the Leukemia Clinic at Princess Margaret Hospital.