Testing the Combination of Nivolumab and ASTX727 for Relapsed or Refractory B-Cell Lymphoma

Inclusion Criteria: * Dose Escalation: Histologically confirmed relapsed or refractory B cell lymphoma (non-Hodgkin lymphoma \[NHL\] or Hodgkin lymphoma \[HL\]) * Dose Expansion: Patients must have histologically confirmed relapsed or refractory DLBCL or HL * Patients with DLBCL must have failed at least first line chemotherapy and must be transplant ineligible (either secondary to performance status or lack of adequate disease control or patient preference). Patients may be relapsed after autologous or allogeneic stem cell transplant (SCT), or after chimeric antigen receptor (CAR)-T cell therapy * In dose escalation patients with HL or B cell NHL other than DLBCL must have relapsed after at least 2 lines of therapy and have no other curative options left. HL patients must be brentuximab vedotin refractory or intolerant. In dose expansion, patients with classic HL must have relapsed after at least 2 lines of therapy, and had autologous stem cell transplantation (ASCT), be ineligible for ASCT, or have refused ASCT. Prior treatment with checkpoint inhibitor is allowed * Age \>= 18 years. Because no dosing or adverse event data are currently available on the use of nivolumab in combination with ASTX727 in patients \< 18 years of age, children are excluded from this study * Eastern Cooperative Oncology Group (ECOG)/Karnofsky performance status =\< 2 (Karnofsky \>= 70%) * Leukocytes \>= 1,500/mcL (unless documented bone marrow involvement in which case lower values may be allowed…