The purpose of this multi-center, single arm, phase Ⅱ clinical trail is to evaluate the efficacy and toxicity of sintilimab combined with R-CHOP regimen as first-line treatment for primary mediastinal large B-cell Lymphoma (PMBCL)

Inclusion Criteria:

• Pathological diagnosis of PMBCL , and did not receive any previous treatment for PMBCL ;
• Predicted survival time ≥ 6 months ;
• 18-75 years ;
• IPI score 0-3；
• ECOG performance status 0-2 ;
• Clinicians judge that the patient is suitable for the treatment of primary mediastinal large B-cell lymphoma ;
• After the patient was enrolled in the trial, other drugs that may have therapeutic effects on primary mediastinal large B-cell lymphoma were not acceptable ;
• WBC ≥ 3 × 109 / L, NE ≥ 1.5 × 109 / L, PLT ≥ 100 × 109 / L ;
• Serum creatinine ≤ 1.5mg / dL, creatinine clearance rate ≥ 50mL / min ;
• ALT, AST ≤ 3 × ULN ( normal upper limit ) ; total bilirubin ≤ 2 × ULN ;
• Sign the informed consent.

Exclusion Criteria:

• Other malignant diseases except PMBCL were diagnosed within 5 years；·Participating in other interventional clinical studies, or has received chemotherapy, radiotherapy, immunotherapy or biotherapy for lymphoma；
• Known allergies to test drugs or any excipient component of these products；·Allogeneic organ transplantation or allogeneic hematopoietic stem cell transplantation has been performed；
• Women in pregnancy or lactation；
• Severe infectious diseases, such as HIV infection, untreated active hepatitis B, active hepatitis C；
• The researchers believe that there are other potential risks that are not suitable for participation in this study.