An Extension Study of the Safety and Anti-leukemic Effects of Imatinib Mesylate in Participants With Philadelphia Chromosome-positive Chronic Myeloid Leukemia in Blast Crisis

Inclusion Criteria: 1\. Participants with Philadelphia chromosome positive chronic myelogenous leukemia (CML) in myeloid blast crisis (including both newly diagnosed and the participants who received prior therapy for accelerated or blastic phases), defined as either: 1. ≥ 30% blast in peripheral blood and /or bone marrow 2. by flow cytometry criteria 2\. To be categorized as "newly diagnosed", participants with CML in blast crisis were not to have received specific therapy for CML accelerated or blast phases, with the exception of interferon-alpha or hydroxyurea. 3\. serum glutamic-oxaloacetic transaminase (SGOT) and serum glutamic-pyruvic transaminase (SGPT) not more than 3 times the upper limit of the normal range (ULN) (or not more than 5 times the ULN if clinically suspected leukemic involvement of the liver), serum creatinine concentration not more than 2 times the ULN, and total serum bilirubin level not more than 3 times the ULN at the laboratory where the analyses were performed. 4\. A negative pregnancy test in participants of childbearing potential. Exclusion Criteria: 1. Participants with an eastern cooperative oncology group (ECOG) performance status score ≥ 3. 2. Participants previously treated for blast crisis were not to have received any of the following with respect to Day 1 of the study: busulfan within six weeks, interferon-alpha within 48-hours, hydroxyurea within 24-hours, homoharringtonine within 14 days, low-dose, moderate dose or high dose cytosine arabinoside within 7, 14 and 28 days respectively, anthracyclines, mitoxantrone, or etoposide within 21 days. 3. Participants receiving any hematopoietic stem cell transplantation within six weeks of Day 1. 4. Participants receiving any other investigational agents within 28 days of Day 1. 5. Participants with Grade 3/4 cardiac disease or any other serious concurrent medical conditions. Other protocol-defined inclusion/exclusion criteria may apply.