This is a prospective, randomized, open-label and active controlled phase II study. It plans to enroll 60 subjects with extensive stage small cell lung cancer (ES-SCLC). All subjects will be assigned randomly to the experimental arm or control arm. The primary endpoints would be overall survival and progression-free survival.

Small cell lung cancer (SCLC) accounts for about 20% of lung cancer, has a high degree of malignancy, short doubling time, early and widespread metastasis, is sensitive to chemotherapy and radiotherapy, and has a high initial response rate, but is prone to secondary drug resistance and relapse. The treatment is mainly based on systemic chemotherapy.

SCLC has a more abundant vascular network than NSCLC. Anti-tumor vascular therapy combined with chemotherapy is considered the most promising SCLC first-line anti-tumor strategy. Anlotinib Hydrochloride has an anti-angiogenic effect and inhibits tumor's growth. It has been reported that Anlotinib has the dual benefits of both overall survival and progression-free survival in the treatment of multiple tumors, and has initially demonstrated its safety and efficacy. The ALTER 0303 study results showed that Anlotinib benefited both the overall and progression-free survival of NSCLC patients. However, there is no clinical study to probe its relevance to small cell lung cancer, and few studies have examined the status of Anlotinib in first-line treatment.

This randomized, open-label, controlled study is to evaluate the efficacy and safety of sequential EL regimen with Anlotinib hydrochloride as first-line treatment for extensive-stage SCLC. The study plan to enroll 60 ES-SCLC subjects and will provide evidence for the use of Anlotinib for SCLC first-line treatment.

Inclusion Criteria:

1. Histopathologically confirmed patients with extensive small cell lung cancer;

2. Karnofsky performance status ≥70;

3. At least one lesion that can measured by CT;

4. Expected to survive for at least 3 months;

5. Peripheral blood and liver and kidney function within the following allowable range (tested within 7 days before treatment);

   • White blood cell (WBC) ≥3.0×109/L or Neutrophils (ANC) ≥1.5×109/L;
   • Hemoglobin (HGB) ≥80 g/L；
   • Platelet (PLT) ≥100×109/L;
   • Liver transaminases（AST/ALT）<3.0 times the normal range limit;
   • Total bilirubin（TBIL）<1.5 times the normal range limit;
   • Creatinine（CREAT）<1.5 times the normal range limit;

6. Patients of childbearing age (including female and male patients' partner) must take effective contraception methods;

7. Signed informed consent;

8. Known history of liver disease: Hepatitis B Virus (HBV) infection and Hepatitis B Virus DNA (HBV DNA ≥500 copies or ≥100 IU/ml); or Hepatitis C Virus (HCV) infection; or liver cirrhosis, etc.

9. Human immunodeficiency virus (HIV);

10. Subjects with difficulties in swallowing or known drug malabsorption; Those who meet each of the above criteria are included in the study.

Exclusion Criteria:

1. Other pathological types of tumor except for small cell lung cancer;
2. Patients with a history of severe allergies or allergies;
3. Pregnancy or breastfeeding women;
4. Patients who have previously participated in other clinical trials and have not yet terminated the trial;
5. Combined with other tumors at the time of initial diagnosis;
6. Patients who have previously participated in other clinical trials and have not yet terminated the trial;
7. Patients who have acute infection that difficult to control;
8. Drug abuse, substance abuse, chronic alcohol abuse, and AIDS patients. Those who meet any of the above criteria are not included in the study.