Patients with relapsed/refractory lymphoma generally have few if any curative options and demonstrate poor response rates to standard salvage therapies. Novel regimens utilizing molecular targets are needed to improve outcomes in this patient population. While studies evaluating single agent small-molecule inhibitors have demonstrated activity in this setting, combinations of these drugs are generally thought to be more efficacious due to targeting separate mechanisms of action and decreased chance of developing resistance. The PD-1/PD-L1 axis is a molecular target that has been demonstrated to be up-regulated in several tumors including malignant lymphoma. Several pre-clinical studies have demonstrated the importance of this axis on clinical outcomes of patients afflicted with low grade lymphoma including FL. Targeting this axis with specific inhibitors would appear to be a rationale way to improve outcomes in patients afflicted with these diseases. PI3K inhibitors in addition to inhibiting signaling, impart changes in the immune cells in the tumor microenvironment and would appear to be a logical candidate to explore in combination with immunotherapy. Based on these preliminary data, we believe that we have justification for proceeding with our proposed phase I study to combine the PD-1 inhibitor, nivolumab, with the PI3K inhibitor, copanlisib, and the CD20 antibody, rituximab, in patients with relapsed/refractory follicular and marginal zone lymphoma. This work has the potential to provide a novel strategy to improve upon the clinical response noted in this patient population.