• Subject volunteered to participate in the study and signed an informed consent;

• Male or female aged ≥18 years and ≤75 years;

• Expected survival time ≥3 months;

• ECOG score 0-1;

• Newly diagnosed patients with extensive-stage small cell lung cancer confirmed by histopathology and / or cytology;

• A archived tumor tissue sample or fresh tissue sample of the primary or metastatic lesion must be provided within 3 years;

• At least one measurable lesion meeting the RECIST v1.1 definition was required;

• No blood transfusion and no use of cell growth factors and/or platelet-raising drugs within 14 days before screening, and the organ function level must meet the requirements;

• The toxicity of previous antineoplastic therapy has returned to ≤ grade 1 as defined by NCI-CTCAE v5.0;

⁃ For premenopausal women of childbearing potential, a pregnancy test must be performed within 7 days before the initiation of treatment, a serum or urine pregnancy test must be negative, and the patient must not be lactating; All enrolled patients should take adequate barrier contraception during the entire treatment cycle and for 6 months after the end of treatment.