A Study to Evaluate Safety, Efficacy and Pharmacokinetics of Rituximab (MabThera/Rituxan) in Participants With Diffuse Large B Cell Lymphoma (DLBCL) or Follicular Lymphoma (FL)

A Single Arm, Multicentre, Phase IIIB Study to Evaluate Safety, Efficacy and Pharmacokinetic (PK) of Subcutaneous (SC) Rituximab Administered During Induction Phase or Maintenance in Previously Untreated Patients With CD20+ Diffuse Large B Cell Lymphoma (DLBCL) or Follicular Lymphoma (FL)

This single arm, multicenter study will evaluate the safety, efficacy and pharmacokinetic (PK) of subcutaneous (SC) rituximab in previously untreated participants with cluster of differentiation 20 positive (CD20+) DLBCL or FL. In addition to standard chemotherapy, participants will receive at least 4 doses of rituximab 1400 mg SC once a month during the Induction period, and at least 6 doses of rituximab 1400 mg SC once every two months during the Maintenance period.

Inclusion Criteria:

• Histologically confirmed, CD20+ DLBCL or CD20+ follicular non-Hodgkin's lymphoma (NHL) Grade 1, 2 or 3a, according to the World Health Organization (WHO) classification system
• Currently being treated with rituximab intravenously (IV) in the Induction or Maintenance period, having received at least one full dose of rituximab IV, defined as standard full dose of rituximab IV 375 milligrams per square-meter (mg/m^2) administered without interruption or early discontinuation (i.e. tolerability issues)
• Expectation and current ability for the participant to receive at least 4 additional cycles of treatment during the Induction period or 6 additional cycles of treatment during the Maintenance period (participants with follicular NHL)
• An International Prognostic Index (IPI) score of 1-4 or IPI score of 0 with bulky disease, defined as one lesion greater than or equal to (>=) 7.5 centimeters (cm), or Follicular Lymphoma International Prognostic Index (FLIPI) (low, intermediate or high risk) assessed before the first rituximab IV administration in Induction period
• At least one bi-dimensionally measurable lesion defined as >=1.5 cm in its largest dimension on computed tomography (CT) scan
• Eastern Cooperative Oncology Group (ECOG) performance status less than or equal to (<=) 3

Exclusion Criteria:

• Transformed lymphoma or FL IIIB
• Primary central nervous system lymphoma, histologic evidence of transformation to a Burkitt lymphoma, primary effusion lymphoma, primary mediastinal DLBCL, DLBCL of the testis, or primary cutaneous DLBCL
• History of other malignancy
• Ongoing corticosteroid use greater than (>) 30 milligrams per day (mg/day) of prednisone or equivalent
• Inadequate renal, hematologic, or hepatic function
• History of severe allergic or anaphylactic reactions to humanized or murine monoclonal antibodies or known sensitivity or allergy to murine products
• Contraindications to any of the individual components of standard chemotherapy
• Other serious underlying medical conditions, which, in the Investigator's judgement, could impair the ability of the participant to participate in the study
• Recent major surgery (within 4 weeks prior to dosing, other than for diagnosis)
• Active hepatitis B virus (HBV), active hepatitis C virus (HCV) infection, or human immunodeficiency virus (HIV) infection