Inclusion Criteria:

          -  Informed consent obtained and signed. Age 18-60 years. ECOG performance status (PS)
             0-2. Histologically confirmed CD20-positive DLBCL, any stage, bulky or nonbulky
             disease.

          -  No prior treatment for lymphoma. Willing to have documentation of HIV status. CD4
             count ≥ 100 cells/µL if HIV-infected. Measurable disease by physical exam.

          -  Adequate bone marrow renal and hepatic function as evidenced by the following:

               -  Absolute neutrophil count (ANC) ≥ 1,000/µL

               -  Platelet count ≥ 100,000/µL

               -  Creatinine ≤ 1.5 mg/dL

               -  Total bilirubin ≤ 2 mg/dL (unless directly attributable to lymphoma)

          -  Able to understand and comply with protocol requirements for the entire length of the
             study.

          -  Willing to reside <50 kilometers from Kamuzu Central Hospital (KCH) until chemotherapy
             completion.

          -  Negative urine B-HCG in women of child-bearing potential within 7 days prior to start
             of treatment.

          -  Fertile patients must use effective contraception (condom or other barrier methods,
             oral contraceptives, implantable contraceptives, intrauterine devices) during and for
             six months after completion of treatment.

        Exclusion Criteria

          -  Pregnant or nursing. Central nervous system (CNS) involvement by lymphoma (clinically
             or cytologically confirmed).

          -  Receiving other anti-cancer or investigational therapy during study treatment, apart
             from those agents specified in the study protocol.

          -  Known cardiac disease including any of the following:

               -  New York Heart Association (NYHA) Grade II or greater congestive heart failure

               -  History of myocardial infarction or unstable angina within 6 months prior to Day
                  1

               -  History of stroke or transient ischemic attack within 6 months prior to Day 1

          -  Second active malignancy requiring systemic therapy.

          -  Hepatitis B virus (HBV) surface-antigen positive unless receiving both tenofovir and
             lamivudine as part of antiretroviral therapy if HIV-infected.

          -  Other serious, ongoing, non-malignant disease or infection that would in the opinion
             of the site investigator compromise other protocol objectives.