• Participants voluntarily enrolled in this study and signed an informed consent form, were compliant and co-operated with follow-up visits;

• Age 18 years and above, male and female;

• Diagnosis of extensive stage small cell lung cancer (ES-SCLC) confirmed by histology or pathology (according to the American Veterans Lung Cancer Association, VALG stage);

• ECOG physical condition score is 0-2;

• Subjects have not received systematic treatment for ES-SCLC in the past (including chemotherapy, VEGFR inhibitors and immune checkpoint inhibitors, etc.)

• Patients with limited stage small cell lung cancer (LS-SCLC) who have received radiotherapy, chemotherapy or radiochemotherapy require a treatment-free period of more than 6 months. Patients with asymptomatic brain metastases are allowed to have cranial radiotherapy during induction chemotherapy;

• Life expectancy \>= 3 months;

• There must be a measurable target lesion that meets the RECIST 1.1 criteria (CT scan length of the tumour lesion \>10mm);

• The function of major organs is normal, that is, the following criteria are met.

‣ Blood routine (not transfused, not using haematopoietic factors and not corrected with drugs within 14 days): ANC ≥ 1.5 x 109/L; HB ≥ 90 g/L; PLT ≥ 100 × 109/L;

⁃ Biochemical tests:

• TBIL ≤ 1.5ULN; TBIL ≤ 1.5 ULN; ALT, AST ≤ 2.5 ULN;

• \- Renal function: Serum creatinine (Cr) ≤ 1.5 x ULN or creatinine clearance ≥ 40 mL/min. (apply the standard Cockcroft-Gault formula):

• \- Coagulation function must meet: INR ≤ 1.5 and APTT ≤ 1.5 ULN;

⁃ Females of childbearing potential must have a negative serum or urine pregnancy test within 72 hours prior to the first dose. Female subjects of childbearing potential and male subjects whose partner is a female of childbearing potential must agree to use a highly effective method of contraception and breastfeeding for the duration of the study up to 90 days after the last administration of study drug. The Investigator or his/her designee, in consultation with the subject, will be required to confirm that the subject has knowledge of how to properly and consistently use the contraceptive method;

⁃ For males, surgical sterilisation or agreement to use a highly effective method of contraception for the duration of the trial and for 90 days after the final administration of study drug;

⁃ For female participants, agreement to refrain from breastfeeding for the duration of the study or for 180 days after the last dose of study treatment is required.