STI571 Plus Combination Chemotherapy in Treating Patients With Chronic Myelogenous Leukemia or Acute Lymphocytic Leukemia

DISEASE CHARACTERISTICS: One of the following diagnoses: Chronic myelogenous leukemia in lymphoid blast crisis Acute lymphoblastic leukemia (ALL) that is in first relapse or failed induction No more than 1 prior course of induction chemotherapy Philadelphia chromosome-positive (Ph+) by cytogenetic analysis OR bcr/abl translocation by fluorescent in situ hybridization At least 30% blasts in bone marrow Ineligible for or refused allogeneic stem cell transplantation Not previously treated with imatinib mesylate OR currently receiving imatinib mesylate with stable disease on 2 bone marrow biopsies at least 2 weeks apart PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Life expectancy: Not specified Hematopoietic: See Disease Characteristics Hepatic: Bilirubin less than 3 times upper limit of normal (ULN) ALT and AST less than 3 times ULN Renal: Creatinine less than 2 times ULN Cardiovascular: No New York Heart Association class III or IV cardiac disease Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective barrier contraception during and for at least 2 weeks after study for female patients and at least 3 months after study for male patients PRIOR CONCURRENT THERAPY: Biologic therapy: See Disease Characteristics No prior allogeneic bone marrow or peripheral blood stem cell transplantation At least 48 hours since prior interferon alfa Chemotherapy: See Disease Characteristics At least 24 hours since prior hydroxyurea At least 6 weeks since prior busulfan Concurrent hydroxyurea or anagrelide for severe leukocytosis or thrombocytosis allowed Endocrine therapy: Not specified Radiotherapy: Not specified Surgery: Not specified Other: No prior therapy for blast crisis except hydroxyurea No prior salvage or reinduction therapy for Ph+ ALL At least 4 weeks since other prior investigational agents