Sintilimab Combined With Anlotinib as Second or Further-line Therapy for ED-SCLC

Inclusion Criteria:

Patients must meet all of the following criteria to be enrolled:

* Histologically or cytologically confirmed ED-SCLC according to the VALG staging system, and not suitable for local treatment.
* Progressed after at least one line of platinum-containing chemotherapy.
* ≥1 measurable lesions based on Response Evaluation Criteria In Solid Tumors version 1.1 (RECIST v1.1).
* Previous radiotherapy was allowed, but the radiotherapy area must be \<25% of the bone marrow area (Cristy and Eckerman 1987) and no total pelvic or chest irradiation was used; the previous radiotherapy must have been completed for at least 4 weeks before the start of study drugs treatment, and the acute toxicity must have been restored; radiotherapy of local lesions cannot be included in measurable lesions unless significant progression is noted after radiotherapy.
* Prior surgery was allowed, provided that the treatment was completed at least 4 weeks before the start of study drugs treatment, and the acute toxicity must have been restored.
* ≥18 years old.
* Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0-2.
* Life expectancy \> 12 weeks.
* Adequate bone marrow, hepatic and renal function.
* Systolic blood pressure ≤160mmHg and diastolic pressure ≤90mmHg within 7 days before enrollment.
* Patients must sign study specific informed consent before registration.
* Female patients should be surgically sterilized, postmenopausal, or consent to use a medically approved contraceptive method (such as an IUD, contraceptive pill, or condom) during the study treatment period and for 6 months after the end of the study treatment period; Serum or urine pregnancy tests must be negative within 7 days prior to study enrollment and must be non-lactating; Male patients should be surgically sterilized or who have consented to use a medically approved form of contraception during the study treatment period and for 6 months after the end of the study treatment period.

Exclusion Criteria:

Any of the following conditions should not be included in this study:

* Patients with brain metastasis. Patients suspected of having brain metastases should be examined by brain CT or MRI before enrollment; Patients with a history of brain metastases must have completed treatment and no longer need corticosteroids; For asymptomatic patients, the investigator will determine whether to enroll.
* Patients with meningeal metastasis.
* Prior treatment with PD-1 inhibitor, PD-L1 inhibitor, CTLA4 inhibitor, or anti-angiogenic treatment.
* Accept any other anti-tumor treatment simultaneously.
* Diagnosed with active autoimmune diseases (congenital or acquired, patients with completely relieved or childhood vitiligo can be enrolled; patients with hypothyroidism and only need hormone replacement therapy can be rerolled; Patients with type 1 diabetes can also be enrolled).
* Diagnosed with interstitial pneumonia.
* Patients with hemorrhage tendency including acute hemorrhage of digestive tract, continuous hemorrhage disease or coagulation function disorder disease.
* Patients are using warfarin, heparin or aspirin (\>325 mg/day) or NSAIDS to inhibit platelet function within 10 days prior to enrollment, or receiving dipyridamole, ticlopidine, clopidogrel or cilostazol treatment.
* Patients with accompanying diseases that seriously endanger the safety of the patient or affect the patient's completion of the study.
* Pregnant or lactating female.
* Prior other malignant diseases, except for cervical carcinoma in situ, papillary thyroid carcinoma, or non-melanoma skin cancer.
* Allergy to any component of the study drugs.