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.