CC-486 and Nivolumab for the Treatment of Hodgkin Lymphoma Refractory to PD-1 Therapy or Relapsed

Inclusion Criteria: * Documented informed consent of the participant and/or legally authorized representative * Assent, when appropriate, will be obtained per institutional guidelines * Be willing to provide tissue from a fresh core or excisional biopsy (performed as standard of care) of a tumor lesion prior to starting study therapy or from archival tissue of a biopsy that was performed after the most recent systemic therapy * Exception may be granted by the principal investigator (PI) if a biopsy is not feasible and/or safe * Age: \>= 18 years * Eastern Cooperative Oncology Group (ECOG) =\< 2 * Histologically confirmed diagnosis of classical Hodgkin lymphoma (excluding nodular lymphocyte predominant Hodgkin lymphoma) according to the World Health Organization (WHO) classification, with hematopathology review at the participating institution * Refractory to PD-1/PD-L1 directed immunotherapy, defined as patients who had prior exposure to PD-1/PD-L1 immunotherapy and either: * Achieved a best response of PD, or * Achieved a best response of CR/PR but developed PD while on active PD-1/PD-L1 treatment or within 12 weeks of last dose of PD-1/PD-L1 treatment * Relapse must have been confirmed histologically (with hematopathology review at the participating institution) * Exceptions may be granted with study PI approval * Patient must have received at least one prior systemic therapy and must not currently be candidate for stem cell transplantation * Measurable disea…