Inclusion Criteria:

Aggressive B-cell non-Hodgkin's lymphoma patients with prior therapy who satisfy the
conditions listed below. No restrictions regarding gender.

- Patients with the following histologically confirmed CD20(+) B-cell non-Hodgkin's
lymphoma:

1. Diffuse large B-cell lymphoma

2. Mantle cell lymphoma

3. Transformed lymphoma

4. Follicular lymphoma (Grade 3)

- Fail to CR in prior chemotherapy, or relapse following CR or recurrence following PR.

- Patients who are judged to carry no effect from the prior therapy (cancer
chemotherapy, antibody therapy and radiation/ radiotherapy.

- Patients aged from 20 to 75 years at the time informed consent is obtained

- Patients with adequately maintained organ functions (e.g., bone marrow, heart, lung,
liver, and kidney functions)

- Patients who can be hospitalized during the first cycle

- Patients capable of personally giving voluntary informed consent in writing to
participate in the study

Exclusion Criteria:

Patients who meet any of the following criteria will be excluded.

- Patients with serious complications (hepatic or renal failure)

- Patients with complications or medical history of serious cardiac disease (e.g.,
myocardial infarction, ischemic heart disease)

- Patients with serious gastrointestinal symptoms (e.g., severe nausea, vomiting, or
diarrhea)

- Patients positive for HBs antigen, HCV antibody, or HIV antibody

- Patients who received other investigational drug or unapproved medication within 3
months before registration in this study

- Patients who had history of hematopoietic stem cell transplantation or
radioimmunotherapy

- Patients who are pregnant, of childbearing potential, or lactating

- Patients, whether male or female, who do not agree to contraception

- Patients otherwise judged by investigator or sub investigator to be unsuitable