An Extension Study to Determine the Efficacy and Safety of STI571 in Participants With Chronic Myeloid Leukemia Who Are Refractory to or Intolerant of Interferon-Alpha

Inclusion Criteria: Participants included in the study were: * Consenting males or females greater than or equal to (≥)18 years of age with Philadelphia chromosome positive (Ph+) chronic myeloid leukemia (CML). * With a documented failure of interferon-alpha (IFN) or an IFN-containing therapy, characterized as resistance or refractoriness defined as any of the following: * Hematologic Resistance - Failure to achieve a complete hematological response (CHR), lasting for at least 1 month despite 6 or more months of IFN or an IFN-containing regimen, in which IFN was administered at a dose of at least 25 million international units (MIU) per week. During this treatment period the cumulative duration of hydroxyurea therapy may not have exceeded 50% of the treatment period with the IFN-containing regimen. * Cytogenetic Resistance - Bone marrow cytogenetics showing ≥65% Ph+ after one year of IFN-based therapy, * Cytogenetic Refractoriness - An increase in the Ph+ chromosome in BM cells by at least 30 percentage points (e.g. from 20% to 50%, or from 30% to 60%) confirmed by two samples at least 1 month apart, or an absolute increase to ≥65%, * Hematologic Refractoriness - A rising white blood cell count (WBC) \[to a level ≥20 x 10\^9/L confirmed by two samples taken at least two weeks apart\] for participants achieving a complete hematologic response while receiving IFN or an IFN-containing regimen. This regimen must have included IFN at a dose of at least 25 MIU administered per week. During this treatment period the cumulative duration of hydroxyurea therapy may not have exceeded 50% of the treatment period with the IFN-containing regimen. In this report all refractory populations were referred to as "relapsed" populations. * With a documented intolerance to IFN therapy defined as a ≥Grade 3 non-hematologic toxicity persisting for at least one month, for participants receiving IFN or an IFN- containing regimen. IFN was to be administered at a dose of at least 25 MIU/week. Participants who were intolerant of IFN were to have been diagnosed ≥6 months prior to the time of entry into the study. Exclusion Criteria: Participants excluded from the study were: * Females of childbearing potential without a negative pregnancy test prior to the initiation of study drug. Barrier contraceptive precautions were to be used throughout the trial in both sexes. * With serum bilirubin and creatinine concentrations more than twice the upper limit of the normal range (ULN). * With serum glutamic oxaloacetic transaminase (SGOT) and serum glutamic pyruvic transaminase (SGPT) more than twice the ULN. * With \>15% of blasts or basophils in peripheral blood (PB) or bone marrow (BM). * With ≥30% of blasts plus promyelocytes in PB or BM. * With a platelet count of less than (\<)100 x 10\^9/L. * With an Eastern Cooperative Oncology Group (ECOG) Performance Status Score ≥3. * Receiving busulfan within 6 weeks of Day 1. * Receiving treatment with IFN or cytosine arabinoside (Ara-C) within 14 days of Day 1. * Receiving treatment with hydroxyurea within 7 days of Day 1. * Receiving other investigational agents within 28 days of Day 1. * With prior marrow or stem cell transplantation.