This study is a one arm, open, single center phase II study. The main purpose of this study was to evaluate the tolerance and preliminary efficacy of SHR1316 combined with chest radiotherapy after induction therapy.

This is a single-arm, single-center phase II study. Eligible subjects will receive the following treatment regimens: 4~6 cycles of SHR1316 combined with EP/EC (etoposide, 100mg/m2, D1-3, q3w and cisplatin, 75mg/m², D1, q3w or carboplatin, AUC=5, D1, q3w). Patients with response sequentially received adebrelimab combined with chest radiotherapy based on investigator decision. Patients then the maintenance therapy with adebrelimab until disease progression or intolerable AEs.

Inclusion Criteria:

• Confirmed diagnosis of Extensive small cell lung cancer
• Eastern Cooperative Oncology Group performance status (PS) of 0 to 1
• 18 to 75 years old
• The function of vital organs meets the following requirements. WBC ≥ 3.0 × 10^9/L, ANC≥1.5×10^9/L, PLT≥100×10^9/L, Hb≥9g/dL, ALT and AST ≤2.5 times ULN, TBIL ≤1.5 x ULN, CREA ≤1.5 times ULN or CCr≥50mL/min. INR≤1.5 x ULN, APTT ≤1.5 x ULN
• have not received first-line systemic therapy or immunosuppressive therapy for es-sclc
• The estimated survival period is more than 8 weeks
• With measurable lesion defined by the RECIST v1.1: Previously irradiated lesions may only be considered as measurable disease if disease progression has been unequivocally documented at that site since radiation and the previously irradiated lesion is not the only site of disease;
• Signed written informed consent prior to study entry

Exclusion Criteria:

• Active or untreated CNS metastases
• Leptomeningeal diseases
• Uncontrolled or symptomatic hypercalcemia
• Active, known or suspected autoimmune diseases
• have received any T cell co stimulation or immune checkpoint therapy
• Corticosteroids (> 10 mg / day prednisone or equivalent) or other immunosuppressants were used within 14 days before the first dose of study drug.
• Subjects had active infections.
• Failing to properly control the clinical symptoms or disease of the heart
• Patients who have previously received allogeneic bone marrow transplantation or solid organ transplantation
• Known to be allergic to the study drug or excipients, known to have a serious allergic reaction to any kind of monoclonal antibody; have a history of hypersensitivity to cisplatin or etoposide
• According to the researcher's judgment, there are other factors that may lead to the termination of the study