PD-L1 Inhibitor Combined With Apatinib as First-line Maintenance Treatment for Extensive-stage Small Cell Lung Cancer

This study is testing whether combining a PD-L1 immunotherapy drug with apatinib (a drug that blocks blood vessel growth in tumors) as maintenance treatment — after initial chemotherapy plus immunotherapy — can keep extensive-stage small cell lung cancer (SCLC) from coming back for longer. **You may be eligible if...** - You are between 18 and 75 years old - You have extensive-stage small cell lung cancer confirmed by biopsy or cytology - You completed first-line treatment with a PD-L1 immunotherapy drug plus chemotherapy, and your cancer responded or stayed stable - You are in generally good health **You may NOT be eligible if...** - Your SCLC developed from a non-small cell lung cancer (NSCLC) - Your cancer has a mixed cell type - You have cancer that has spread to the lining of the brain (meninges) - You have symptomatic brain metastases (asymptomatic or treated and stable brain metastases may be acceptable) - You have poorly controlled heart disease, active autoimmune disease, or serious infections - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.