the Efficacy and Safety of CLAE in R/R T-ALL/LBL

Inclusion Criteria: * Diagnosis of T-acute lymphoblastic leukemia/lymphoblastic lymphoma according to World Health Organization (WHO) criteria which has relapsed or is refractory to chemotherapy. * Age ≥ 18 years. * Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2. * The expected survival period is more than 12 weeks. * At least one measurable nidus * Adequate organ function defined as: * Calculated creatinine clearance ≥ 50 ml/min using the cockcroft -Gault formula * AST, ALT, total bilirubin ≤ 2 x upper limit of normal (ULN) except for Gilbert's disease or when in the opinion of treating physician elevated levels are due to direct involvement of leukemia (e.g., hepatic infiltration or biliary obstruction due to leukemia), in which case ALT and AST may be elevated up to ≤ 5 x ULN. * Able to understand and willing to sign an Institutional Review Board (IRB)-approved written informed consent document. Exclusion Criteria: * Previous treatment with nelarabine or clofarabine or fludarabine or cladribine was ineffective. * Pregnant or nursing. * Received any other investigational agent or systemic cytotoxic chemotherapy within the preceding 2 weeks. * Active HIV or hepatitis B or C infection. * Any medical condition which, in the opinion of the clinical investigator, would interfere with the evaluation of the patient. Subjects with a clinically significant or unstable medical or surgical condition or any other condition that cannot be well-controlled by the allowed medications permitted in the study protocol that would preclude safe and complete study participation, as determined by medical history, physical examinations, laboratory tests, and according to the investigator's judgment.