Azacitidine Plus PD-1 Therapy for R/R Hodgkin Lymphoma

Inclusion Criteria: * Pathologically confirmed Hodgkin Lymphoma according World Health Organization (WHO) classification. * Patient is ≥ 18 years of age at the time of signing the informed consent form (ICF). * Patient must understand and voluntarily sign an ICF prior to any study-specific assessments/procedures being conducted. * Patient is willing and able to adhere to the study visit schedule and other protocol requirements. * Relapsed (after partial or complete response) or refractory AITL after at least one line of systemic therapy (there is no mandatory resting period after the previous treatment as long as the biochemistry and hematology labs meet the inclusion criteria as below). * Meet the following lab criteria: Absolute Neutrophil Count (ANC) ≥ 1,5 x 10\^9/L (≥ 1 x 10\^9/L if bone marrow (BM) involvement by lymphoma); Platelet ≥ 75 x 10\^9/L (≥ 50 x 10\^9/L if BM involvement by lymphoma); Hemoglobin ≥ 8 g/dL. * Anticipated life expectancy at least 3 months. Exclusion Criteria: * Active or uncontrolled infections requiring systemic treatment within 14 days before enrollment. * Any instability of systemic disease, including but not limited to severe cardiac, liver, kidney, or metabolic disease need therapy. * Pregnant or lactating women.