PRIMARY OBJECTIVES:~I. Assess the safety and toxicity of atezolizumab in combination with immunogenic chemotherapy (gemcitabine plus oxaliplatin) with rituximab (R-GEMOX-ATEZO) in patients with relapsed or refractory (rel/ref) transformed diffuse large B-cell lymphoma (DLBCL), including determination of the maximum tolerated dose (MTD) and the recommended phase II dose (RP2D) of R-GEMOX-ATEZO.~II. Evaluate on-treatment changes in density of and proximity between immune cell subsets in the tumor microenvironment after immunogenic chemotherapy alone and R-GEMOX-ATEZO by multispectral immunofluorescence, including density of CD8+ cells and cytotoxic lymphocyte (CTL):regulatory T cell (Treg) ratio.~SECONDARY OBJECTIVES:~I. To observe and record anti-tumor activity. II. Evaluate genomic (e.g. gene expression profiles, whole exome sequencing) characteristics of patients with rel/ref transformed DLBCL treated with R-GEMOX-ATEZO.~OUTLINE:~INDUCTION PHASE: Patients receive rituximab intravenously (IV), gemcitabine IV, and oxaliplatin IV every 2 weeks. Starting cycle 2, patients also receive atezolizumab IV over 30-60 minutes every 2 weeks. Treatment repeats every 14 days of cycle 1 and every 28 days for up to 4 cycles in the absence of disease progression or unaccepted toxicity. Patients also undergo computed tomography (CT), positron emission tomography (PET)-CT, magnetic resonance imaging (MRI), bone marrow biopsy, collection of blood samples, and tumor biopsy throughout induction phase.~MAINTENANCE PHASE: Patients receive rituximab IV and atezolizumab over 30-60 minutes IV on day 1. Cycles repeat every 3 weeks in the absence of disease progression or unaccepted toxicity. Patients also undergo CT, PET-CT, MRI, bone marrow biopsy, and collection of blood samples throughout maintenance phase.~After completion of study treatment, patients are followed up at 30 days and then every 6 months for up to 1 year.
This pilot phase I trial studies the side effects of atezolizumab, gemcitabine, oxaliplatin, and rituximab and to see how well they work in treating patients with transformed diffuse large B-cell lymphoma that has come back (relapsed) or does not respond to treatment (refractory). Immunotherapy with monoclonal antibodies, such as atezolizumab, may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. Drugs used in chemotherapy, such as gemcitabine and oxaliplatin, work in different ways to stop the growth of cancer cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Rituximab is a monoclonal antibody. It binds to a protein called CD20, which is found on B cells (a type of white blood cell) and some types of cancer cells. This may help the immune system kill cancer cells. Giving atezolizumab, gemcitabine, oxaliplatin, and rituximab may work better in treating patients with transformed diffuse large B-cell lymphoma.