Small cell lung cancer is a highly aggressive malignancy. Currently, there is no effective regimen for patients after the progression offirst-line chemotherapy. The prognosis of patients with extensive disease is very poor, and the improved therapeutic efficacy is urgently needed. Most patients with small cell lung cancer have a long history of smoking, and the tumor mutation burden is relatively high, which provides potential for immunological checkpoint inhibitors represented by PD-1 antibodies. A number of studies have shown that chemotherapy combined with adoptive cellular immunotherapy could prolong the survival of patients. This study is a clinical study to explore the efficacy and safety of maintenance therapy with sintilimab after 4-6 cycles of first-line chemotherapy combined with adoptive cellular immunotherapy in patients with advanced small cell lung cancer.

Inclusion Criteria:

• small cell lung cancer confirmed by pathology
• extensive small cell lung cancer by imaging
• at least one measurable lesion by RECIST 1.1
• ECOG 0-1
• adequate organ function
• no other severe diseases conflicting with this regimen (such as autoimmune diseases, immunodeficiency, organ transplantation, etc)
• no history of other maliganancies
• Women of childbearing period must examinate for a negative pregnancy test within 7 days, use appropriate contraceptive measures during the study and 6 months after the trial.
• agreement to participate in the study and signed informed consent from the patients

Exclusion Criteria:

• serious infectious diseases four weeks before enrollment
• requirement intermittent use of bronchodilators or medical interventions;
• the use of immunosuppressants before the enrollment, the amount of immunosuppressant used ≥10mg / day oral prednisone for more than 2 weeks;
• severe allergies
• severe mental disorders
• abnormal coagulation function
• previous or current pulmonary fibrosis, interstitial pneumonia, pneumoconiosis, radiation pneumonitis, severe lung damage, etc.
• other situations considered by investigators not meet the inclusion criteria (including but not limited to symptomatic brain metastases)