OBJECTIVES:~Determine whether interferon alfa in combination with imatinib mesylate adds to the hematologic, cytogenetic, and molecular response rates in patients with chronic phase chronic myelogenous leukemia that is newly diagnosed or has not achieved a complete cytogenetic response to imatinib mesylate alone.~OUTLINE: Patients receive oral imatinib mesylate (STI-571) once daily for 9 months. At 9 months, patients with more than 35% Philadelphia chromosome-positive (Ph+) cells in bone marrow receive oral STI-571 twice daily for 3 more months. At 12 months, patients with more than 35% Ph+ cells in bone marrow receive oral STI-571 once daily and interferon alfa subcutaneously once daily. Treatment continues for at least 1 year in the absence of disease progression or unacceptable toxicity. Patients with an appropriate HLA-matched donor may choose to have a bone marrow transplantation at any time during the study.~Patients are followed every 6 months for 3 years.~PROJECTED ACCRUAL: A total of 80 patients (60 without an HLA-matched donor and 20 with an HLA-matched donor) will be accrued for this study within 5 years.
RATIONALE: Interferon alfa may interfere with the growth of cancer cells. Imatinib mesylate may stop the growth of cancer cells by blocking the enzymes necessary for cancer cell growth. Combining interferon alfa with imatinib mesylate may kill more cancer cells.~PURPOSE: Phase II trial to study the effectiveness of combining interferon alfa with imatinib mesylate in treating patients who have chronic myelogenous leukemia.