Sintilimab Combined With Tafolecimab and Chemotherapy as First-Line Treatment for Extensive-Stage Small Cell Lung Cancer

Key Inclusion Criteria: * Age ≥18 years, ECOG performance status 0-1; * Histologically or cytologically confirmed extensive-stage small cell lung cancer (ES-SCLC) according to Veterans Administration Lung Study Group criteria; * Previously not receiving systemic treatment for ES-SCLC; * Greater than or equal to 1 measurable lesion exists according to RECIST v1.1; * Expected survival \>= 12 weeks; * Adequate organ system functions (no blood transfusion or component blood use within 14 days before testing). Key Exclusion Criteria: * Previously receiving systemic anti-tumor therapy for ES-SCLC; * Combined SCLC (mixed SCLC and NSCLC histological types) or transformed SCLC confirmed by histological or cytological examination; * Receiving other investigational drugs or participated in other interventional clinical studies within 4 weeks before signing the informed consent form; * Receiving systemic immunostimulant treatment within 4 weeks before enrollment; * Active central nervous system (CNS) metastases (asymptomatic patients with stable lesions allowed); * Severe cardiovascular disease; * Severe chronic/active infections requiring systemic antibacterial, antifungal or antiviral treatment within 2 weeks before enrollment; * Active hepatitis B virus (HBV)/ hepatitis C virus (HCV)/ human immunodeficiency virus (HIV) infection; * Active autoimmune diseases, a history of interstitial lung disease, or other uncontrolled systemic diseases; * Pregnancy or lactation; * Having a disease that requires systemic corticosteroids or other immunosuppressants to be treated within ≤14 days before enrollment; * Requiring at least monthly or more frequent drainage of pleural and/or pericardial or peritoneal effusion; * Using attenuated live vaccines, or planned to receive attenuated live vaccines within 28 days before enrollment; * Known to be allergic to Sintilimab or Tafolecimab or its excipients, having a history of severe allergic reaction to any monoclonal antibody, or having a history of allergy to cisplatin, carboplatin or etoposide; * Toxicity caused by previous anti-cancer treatment has not recovered to baseline or stable state at the time of enrollment; * Creatinine clearance rate \< 60 mL/min (cisplatin) or \< 45 mL/min (carboplatin) * Uncontrolled or symptomatic hypercalcemia.