This is a prospective international, multi-center, randomized, double-blind controlled study designed to assess and compare the pharmacokinetics, pharmacodynamics and the safety of PBO-326 (Rituximab) and Mabthera (Rituximab) in combination with CHOP in previously untreated patients with diffuse B cells Non Hodgkin lymphoma.

At present R-CHOP (Rituximab plus Cyclofosfamide, Doxorrubicine, Vincristine and Prednisone) has became standard of care of patients with B cells Non Hodgkin Lymphoma CD20+.

Study will perform pharmacodynamic (PD) and pharmacokinetic (PK) measurment of a novel Rituximab in comparison with Mabthera and evaluates safety both metabolic as well immunologic.

Study protocolo is designed to provide data on impact of treatment interchange of both study drugs (PBO-326 and Mabthera).

Inclusion Criteria:

1. Newly diagnosed subjects with a confirmed pathologic diagnosis of diffuse large B cell non-Hodgkin's lymphoma (DLBCL) based on the 2008 World Health Organization classification.
2. CD20+ lymphoma cells at screening.
3. > 18 years of age at screening.
4. Ann Arbor Stages I-IV at screening.
5. Any IPI score at screening.
6. Easten Cooperative Oncology Group (ECOG) performance status (0-2) or Karnofsky scale > 60 at screening.
7. Left ventricular ejection fraction > 50%.
8. Willing and able to provide written informed consent prior to performing study procedures.
9. Women of childbearing potential must use effective contraceptive methods starting from screening and until 12 months following the last infusion.

Exclusion Criteria:

1. Hodgkin lymphoma.
2. Any lymphoma other than CD20+ Diffuse Large B Cell Lymphoma (DLBCL).
3. Immunodeficiency syndrome or Human immunodeficiency virus (HIV) seropositivity .
4. Active uncontrolled infection (viral, bacterial or fungal infection) requiring systemic therapy at screening and/or at baseline visit.
5. Function Liver tests >2 x upper normal values.
6. Positive Hepatitis B surface antigen or antibodies to Hepatitis C.
7. Any other serious active disease or co-morbid medical condition.
8. Subjects who, according to the investigator, are likely to be non-compliant or uncooperative during the study.
9. Pregnant or breast-feeding women or women that intend to get pregnant during study or within 12 months following the last infusion.
10. Treatment with any investigational drug within 90 days before day 1 of study treatment.