A Notch Signalling Pathway Inhibitor for Patients With T-cell Acute Lymphoblastic Leukemia/Lymphoma (ALL)(0752-013)

Inclusion Criteria: Patients must have pathologically documented precursor T-cell acute lymphoblastic leukemia/lymphoma (T-ALL), relapsed or refractory to standard therapy, or not be a candidate for standard myelosuppressive chemotherapy due to age or comorbid disease. Patient must have performance status <2 on the ECOG performance status for patients >16 years old; Lansky performance level >50 for patients 12 months to less than or equal to 16 years old. Patient must have adequate renal and liver function as indicated by the laboratory values performed within 14 days of receiving the first dose of study drug. Patient must have fully recovered from any chemotherapy and be greater than 2 weeks from radiotherapy, immunotherapy, or systemic steroid therapy with the exception of hydroxyurea, intrathecal therapy, or immunosuppressant therapy for chronic graft-versus-host disease prophylaxis following allogeneic bone marrow transplant. Patient must be greater than 2 months following bone marrow or peripheral blood stem cell transplantation and off all immunosuppressant therapy (with the exception of patients taking immunosuppressant therapy for chronic graft-versus-host disease prophylaxis following allogeneic bone marrow transplant). Men and women of reproductive potential must use an effective contraceptive method while enrolled in the study. Patient or the patient's legal representative must be able to understand the study and give written informed consent. Exclusion Criteria: Patient has had treatment with any investigational therapy during the preceding 30 days. Patient has uncontrolled congestive heart failure, angina, or had a myocardial infarction in the preceding 3 months. Patient has known hypersensitivity to the components of study drug, its analogs, or to allopurinol. Patient has active or uncontrolled infection. Patient has known psychiatric or substance abuse disorders that would interfere with cooperation with the requirements of the trial. Patient is pregnant or lactating. Patient has any other severe concurrent disease which would make the patient inappropriate for entry into this study. Patient is known to be HIV positive or who has an AIDS-related illness. Patients with a "currently active" second malignancy, other than non-melanoma skin cancer should not be enrolled. Patient has isolated CNS disease.