The purpose of this study is to evaluate the safety and efficacy of SHR-1316 in combination with Fluzoparib（SHR-3162） in Small Cell Lung Cancer Patients

Inclusion Criteria:

• Patients must be at least 18 years of age.
• Histologically or cytologically confirmed SCLC.
• Failed at least one prior line of platinum-based chemotherapy.
• Patients must have measurable disease as defined by RECIST v1.1.
• ECOG 0-1.
• Adequate hematologic and organ function
• Signed inform consent form

Exclusion Criteria:

• Active or untreated central nervous system (CNS) metastases
• Spinal cord compression not definitively treated with surgery and/or radiation .
• Leptomeningeal disease
• Uncontrolled pleural effusion, pericardial effusion, or ascites requiring recurrent drainage procedures
• Malignancies other than SCLC within 5 years prior to randomization
• History of autoimmune disease
• Positive test result for human immunodeficiency virus (HIV)
• Active hepatitis B or hepatitis C
• Severe infections
• Subjects with a condition requiring systemic treatment with either corticosteroids (>10 mg daily prednisone equivalent) or other immunosuppressive medications within 14 days of first administration of study treatment.
• Significant cardiovascular disease
• Prior allogeneic bone marrow transplantation or solid organ transplant
• Treatment with systemic immunosuppressive medications prior to randomization
• Pregnant or lactating women
• History or current evidence of any condition, therapy, or laboratory abnormality that might confound the results of the study, interfere with the subject's participation for the full duration of the study, or is not in the best interest of the subject to participate, in the opinion of the treating investigator.