Phase 3 Study Evaluating Efficacy, Safety and Pharmacokinetics of Trilaciclib In Small Cell Lung Cancer Patients

Inclusion Criteria:

1. Age ≥ 18 years, male or female;
2. Histologically or cytologically confirmed extensive stage small cell lung cancer (ES-SCLC):

   * Patients scheduled to receive carboplatin plus etoposide regimen: no prior systemic therapy (eg, chemotherapy or combined with immunotherapy);
   * Patients scheduled to receive topotecan regimen: previously received 1/2 lines of chemotherapy or combined immunotherapy but not topotecan.
3. Presence of at least one radiation-naïve measurable lesion according to RECIST 1.1 criteria;
4. Hemoglobin ≥ 90 g/L;
5. Neutrophil count ≥ 1.5 × 10\^9/L;
6. Platelet count ≥ 100 × 10\^9/L;
7. Creatinine ≤ 15 mg/L or creatinine clearance (CrCl) ≥ 60 mL/min (Cockcroft-Gault formula);
8. Total bilirubin ≤ 1.5 × upper limit of normal (ULN);
9. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 3 × ULN or ≤ 5 × ULN (for patients with liver metastases);
10. Albumin ≥ 30 g/L;
11. ECOG PS score 0 - 2;
12. Expected survival time ≥ 3 months;
13. Contraception:

    Females: All females of childbearing potential must have a negative serum pregnancy test at screening and must use reliable contraception from signing of informed consent through 3 months after the last dose; Male: Female partners of childbearing potential must use reliable contraception from signing the informed consent until 3 months after the last dose;
14. Understand and sign informed consent

Exclusion Criteria:

1. Symptomatic brain metastases requiring local radiotherapy or hormonal therapy;
2. History of other malignancies, with the following exceptions: (1) clinically cured cutaneous basal cell or squamous cell tumors; (2) cured a) cervical cancer, b) prostate cancer, c) superficial bladder cancer; or (3) other solid tumors with a clinical cure time of more than 3 years;
3. Uncontrolled ischemic heart disease or clinically significant congestive heart failure (NYHA Class III or IV);
4. Stroke or cardiovascular or cerebrovascular event within 6 months prior to enrollment;
5. Severe active infection;
6. Psychological or other social factors causing insufficient trial compliance;
7. Other uncontrolled serious chronic diseases or conditions that, in the opinion of the investigator, would make participation in the trial inappropriate;
8. Known HIV infection, active hepatitis B (defined as positive HBV DNA), and hepatitis C (positive HCV RNA);
9. Radiation therapy within 2 weeks prior to enrollment;
10. Patients who have received cytotoxic drug therapy or investigational drug therapy within 4 weeks before enrollment, or non-cytotoxic anti-tumor drug therapy within 2 weeks;
11. Subjects in the first part of the study should not take strong or moderate inducers of CYP3A4 concomitantly within 4 weeks before taking the study drug, and strong inhibitors of CYP3A4 concomitantly within 2 weeks before taking the study drug;
12. Toxicity from prior anticancer therapy has not recovered to Grade 0 or 1 (except alopecia);
13. Hypersensitivity to the study drug (Trilaciclib, etoposide, carboplatin, topotecan) or components thereof;
14. Persons who are unable to act independently due to legal restriction or legal sense;
15. Pregnant or lactating women;
16. Not suitable for participating in this study in the investigator 's opinion.