To investigate safety and efficacy on Japanese subjects treated with nelarabine injection for intravenous use in clinical settings of the following diseases:

1. T-cell acute lymphocytic leukemia (T-ALL)
2. T-cell lymphoblastic lymphoma (T-LBL) Also, "any adverse events involving neurological disorder, hypotension, and blood disorder and their details" are to be investigated as an item of particular concern. In addition, subject outcome (alive or dead) at one year after the start of treatment will also be investigated.

Inclusion Criteria:

• Diagnosis of T-cell acute lymphocytic leukemia (T-ALL) or T-cell lymphoblastic lymphoma (T-LBL)

Exclusion Criteria:

• Subjects with hypersensitivity to nelarabine

Subjects with the following diseases in Japanese adults and children

1. T-cell acute lymphocytic leukemia (T-ALL)
2. T-cell lymphoblastic lymphoma (T-LBL)