Inclusion Criteria:

- Patients under consideration for participation in this study must meet all of the
following inclusion criteria:

- Histologically confirmed CD20 positive diffuse large B-cell lymphoma.

- Progressing or relapsed following prior treatment including but not limited to
rituximab-CHOP chemotherapy regimen.

- Not suitable for ASCT (age > 60 years, PS ≥ 2, prior ASCT as a part of the previous
treatment for DLBCL, and/or other medical conditions that unable the patients to
undergo the ASCT, e.g. NYHA II, creatinine clearance < 50 mL/min).

- Age ≥ 18 years.

- ECOG/ WHO performance status grades 0 - 3.

- Resolution of toxicities from previous therapy to grade ≤ 1.

- Written signed and dated informed consent prior to any study procedures being
performed.

Exclusion Criteria:

- Known or suspected hypersensitivity to study treatments.

- Prior treatment with anti-CD20 monoclonal antibodies with the exception of rituximab.

- Screening laboratory values:

- platelets < 75 x 109/L (unless due to DLBCL involvement of the bone marrow),

- neutrophils < 1.5 x 109/L (unless due to DLBCL involvement of the bone marrow),

- creatinine > 2.0 times upper normal limit (unless normal creatinine clearance),

- total bilirubin >1.5 times upper normal limit (unless due to DLBCL involvement
of liver or a known history of Gilbert's disease),

- ALT > 2.5 times upper normal limit (unless due to DLBCL involvement of liver),

- alkaline phosphatase > 2.5 times upper normal limit (unless due to DLBCL
involvement of the liver or bone marrow).

- Subjects who have current active hepatic or biliary disease (with exception of
patients with Gilbert's syndrome, asymptomatic gallstones, liver metastases or stable
chronic liver disease per investigator assessment).

- Treatment with any known non-marketed drug substance or experimental therapy within 5
terminal half lives or 4 weeks prior to enrolment, whichever is longer, or currently
participating in any other interventional clinical study.

- Other past or current malignancy. Subjects who have been free of malignancy for at
least 5 years, or have a history of completely resected non-melanoma skin cancer, or
successfully treated in situ carcinoma are eligible.

- Chronic or current infectious disease requiring systemic antibiotics, antifungal, or
antiviral treatment such as, but not limited to, chronic renal infection, chronic
chest infection with bronchiectasis, tuberculosis and active Hepatitis C.

- History of significant cerebrovascular disease in the past 6 months or ongoing event
with active symptoms or sequel.

- Known HIV positive.

- Clinically significant cardiac disease including unstable angina, acute myocardial
infarction within six months prior to randomization, congestive heart failure (NYHA
III-IV), and arrhythmia unless controlled by therapy, with the exception of extra
systoles or minor conduction abnormalities.

- Significant concurrent, uncontrolled medical condition including, but not limited to,
renal, hepatic, gastrointestinal, endocrine, pulmonary, neurological, cerebral or
psychiatric disease which in the opinion of the investigator may represent a risk for
the patient.

- Positive serology for Hepatitis B (HB).

- Positive serology for hepatitis C (HC).

- Pregnant or lactating women. Women of childbearing potential must have a negative
pregnancy test at screening.

- Women of childbearing potential, including women whose last menstrual period was less
than one year prior to screening, unable or unwilling to use adequate contraception
from study start to one year after the last dose of protocol therapy.

- Male subjects unable or unwilling to use adequate contraception methods from study
start to one year after the last dose of protocol therapy.

- Patients unwilling or unable to comply with the protocol.