This single-arm, Phase II, multicenter study was designed to evaluate the safety and efficacy of Camrelizumab (anti-programmed death-receptor 1 [PD-1] antibody) in combination with Apatinib+carboplatin plus (+) etoposide in chemotherapy-naive participants with ES-SCLC. Participants will be receive camrelizumab +apatinib+ carboplatin + etoposide on 21-day cycles for four -six cycles in the induction phase followed by maintenance with camrelizuab +apatinib until progressive disease (PD) as assessed by the investigator using Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST v1.1). Treatment can be continued until persistent radiographic PD or symptomatic deterioration.

Inclusion Criteria:

• 18 and 70 years old
• Histologically or cytologically confirmed ES-SCLC (per the Veterans Administration Lung Study Group [VALG] staging system);
• No prior systemic treatment for ES-SCLC；
• Has received radiotherapy and chemotherapy for limited stage SCLC must have received definitive treatment, and has at least 6 months of no treatment interval from the last treatment to the diagnosis of extensive SCLC
• Eastern Cooperative Oncology Group performance status of 0 or 1；
• life expectancy≥ 12 weeks
• Adequate hematologic and organ function
• Male or female subjects should agree to use an adequate method of contraception starting with the first dose of study therapy through 90 days after the last dose of study (such as intrauterine devices , contraceptives or condoms) ; No pregnant or breastfeeding women, and a negative pregnancy test are received within 72h before the first dose of the study.

Exclusion Criteria:

• Has prior therapy with apatinib,anlotinib, anti-programmed cell death (PD)-1, anti-PD-L1 or other immunotherapy against PD-1/PD-L1;
• Has active or untreated central nervous system (CNS) metastases and/or cancerous meningitis;
• Has spinal cord compression which was not cured or relieved through surgery and/or radiotherapy, or diagnosed spinal cord compression after treatment showed no clinical evidence of disease stabilization prior to allocation ≥1 week;
• Imaging (CT or MRI) shows that tumor invades large blood vessels or the boundary with blood vessels is unclear;
• Active autoimmune diseases requiring systemic treatment occurred within 2 years prior to first administration ;
• Immunosuppressive therapy with immunosuppressive agents or systemic or absorbable local hormones (dosage > 10 mg/day prednisone or other therapeutic hormones) is required for the purpose of immunosuppression, and is still in use for 2 weeks after the first administration;
• Has arterial or venous thromboembolic events occurred within 6 months, such as cerebrovascular accident including transient ischemic attack, deep vein thrombosis and pulmonary embolism;
• Within 3 months prior to initial administration, subjects with evidence of bleeding had clinical significance or history of bleeding tendency, regardless of severity;
• Has vaccinated with vaccines or attenuated vaccines within 4 weeks prior to first administration
• Has major surgical procedure、biopsy or obvious traumatic injury within 28 days before allocation;
• Has participated in other anticancer drug clinical trials within 4 weeks;
• Has diagnosed and/or treated additional malignancy within 5 years prior to allocation. Exceptions include cured basal cell carcinoma of skin and carcinoma in situ of cervix;
• Has any severe and/or uncontrolled disease;
• Has adverse events caused by previous therapy except alopecia that did not recover to ≤ grade 1;
• Has drug abuse history that unable to abstain from or mental disorders; 13. Has any severe and/or uncontrolled disease;
• Severe hypersensitivity occurs after administration of other monoclonal antibodies;
• According to the judgement of the researchers, there are other factors that may lead to the termination of the study.