A Study of ZL-1310 in Combination With a Checkpoint Inhibitor Versus Standard of Care Platinum Based Chemotherapy With a Checkpoint Inhibitor as First-line Therapy in Participants With Extensive-Stage Small Cell Lung Cancer

Inclusion Criteria: * Histologically or cytologically confirmed ES-SCLC * No prior systemic therapy has been received * Medically eligible to receive standard platinum-based chemotherapy with atezolizumab or durvalumab as first-line therapy * Eastern Cooperative Oncology Group performance status of 0 or 1 * Life expectancy of at least 3 months * Adequate organ and marrow function Exclusion Criteria: * Has a contraindication to receive atezolizumab or durvalumab according to local drug label or local treatment guideline * Participants with symptomatic CNS metastases (require initiation or dose change of steroids or anti-convulsant within 7 days prior to randomization; require steroid dose higher that prednisone 10 mg/day or equivalent within 14 days prior to randomization * History of ILD/pnuemonitis (non-infectious) that required corticosteroids, current ILD/pnuemonitis of any grade, or suspected ILD/pnuemonitis that cannot be ruled out by imaging at screening * Received radiotherapy within 2 weeks to the non-thoracic and within 4 weeks to the thoracic area prior to the first dose of study treatment or received more than 30 Gy of thoracic radiotherapy * Clinically significant active cardiovascular disease or history of any arterial thromboembolic event within 6 months prior to the first dose of study treatment * Clinically severe pulmonary compromise (including but not limited to baseline oxygen saturation of \<90% on room air) resulting from intercurrent pulmonary illnesses * Major surgery within 4 weeks prior to the first dose of study treatment.