PD-1 Inhibitor or PD-1 Inhibitor Plus GVD for Relapsed/Refractory CHL

Inclusion Criteria:

* Histologically confirmed classical Hodgkin lymphoma;
* Refractory to or relapsed after first-line induction therapy; prior radiotherapy is allowed;
* At least one evaluable lesion according to 2014 Lugano criteria;
* Life expectancy \> 3 months;
* Eastern Cooperative Oncology Group (ECOG) of 0-1;
* Able to participate in all required study procedures;
* Proper functioning of the major organs: 1) The absolute value of neutrophils (\>1.5×10\^9/L); 2) platelet count (\> 75×10\^9/L); 3) Hemoglobin (\> 80 g/L); 4) Serum creatinine \<1.5 times Upper Limit Normal (ULN) ; 5) Serum total bilirubin \< 1.5 times ULN; 6) Aspartate Aminotransferase (AST), Alanine Aminotransferase (ALT) \< 2.5 times ULN; 7) Coagulation function: International Normalized Ratio (INR), Prothrombin Time (PT), Activated Partial Thromboplastin Time (APTT) \< 1.5 times ULN (unless the subject is receiving anticoagulant therapy and PT and APTT are within the expected range at screening time). ; 8) Thyrotropin (TSH) or free thyroxine (FT4) or free triiodothyronine (FT3) were all within the normal range (±10%);
* There was no evidence that subjects had difficulty breathing at rest, and the measured value of pulse oximetry at rest was more than 92%;
* Volunteers who signed informed consent.

Exclusion Criteria:

* Involvement of central nervous system (CNS);
* Previously received treatment of immune checkpoint inhibitors (eg. PD-1, PD-L1, CTLA-4);
* Previously received treatment of hematopoietic cell transplantation;
* Patients with Hemophagocytic syndrome;
* Patients with active autoimmune diseases requiring systematic treatment in the past two years (hormone replacement therapy is not considered systematic treatment, such as type I diabetes mellitus, hypothyroidism requiring only thyroxine replacement therapy, adrenocortical dysfunction or pituitary dysfunction requiring only physiological doses of glucocorticoid replacement therapy); Patients with autoimmune diseases who do not require systematic treatment within two years can be enrolled;
* Requiring treatment with corticosteroids or other immunosuppressive drugs within 14 days of study drug administration \[allowing subjects to use local, ocular, intra-articular, intranasal and inhaled glucocorticoid therapy (with very low systemic absorption); and allowing short-term (\< 7 days) glucocorticoid prophylaxis (e.g., contrast agent overdose sensitivity) or for the treatment of non-autoimmune diseases (e.g. delayed hypersensitivity caused by contact allergens).
* Uncontrolled active infection, with the exception of tumor-related B symptom fever;
* History of human immunodeficiency virus (HIV) infection and/or patients with acquired immunodeficiency syndrome are known;
* Patients with active hepatitis B or active hepatitis C. Patients who are positive for hepatitis B Surface Antigen (HBsAg) or hepatitis C Virus (HCV) antibodies at screening stage must pass further detection of hepatitis B Virus (HBV) DNA (no more than 10\^4 copies/mL) and HCV RNA (no more than the lower limit of the detection method) in the row. Hepatitis B carriers, stable hepatitis B (DNA titer should not be higher than 10\^4 copies/mL) after drug treatment, and cured hepatitis C patients can be enrolled in the group;
* Diagnosed with or receiving treatment for malignancy other than lymphoma;
* Pregnant or breastfeeding women;
* Other researchers consider it unsuitable for patients to participate in this study.