Efficacy Study of Imatinib Mesylate to Treat Philadelphia-Positive Acute Lymphocytic Leukemia

Inclusion Criteria: * Patients with histologically confirmed diagnosis of ALL. * Patients confirmed to be Ph chromosome positive or bcr-abl gene positive. * Patients in relapse * Patients refractory to initial remission induction therapy * Patients ineligible for initial remission induction therapy * Patients with an ECOG Performance Status Score from 0 to 2 * Serum creatinine concentration of not more than 2 × the upper limit of the normal range (ULN) * AST (SGOT) and ALT (SGPT) of not more than 3 × ULN. In patients with hepatic dysfunction from leukemic involvement, AST (SGOT) and ALT (SGPT) should be not more than 5 × ULN * Serum bilirubin level not more than 3 × ULN Exclusion Criteria: * Patients with findings indicative of leukemic involvement of the central nervous system * Patients with any serious concomitant medical condition (e.g., poorly controllable infection, interstitial pneumonia, pulmonary fibrosis, congestive cardiac failure, poorly controlled diabetes mellitus, mental disorder) * Patients expected to receive any hematopoietic stem cell transplantation within 6 weeks of the planned initiation of the study drug * Patients having received any hematopoietic stem cell transplantation who have a Grade 3 or 4 GVHD. Other protocol-defined inclusion/exclusion criteria may apply.