A Study of Atezolizumab Plus Tiragolumab in Combination With Paclitaxel and Cisplatin Compared With Paclitaxel and Cisplatin as First-Line Treatment in Participants With Unresectable Locally Advanced, Unresectable Recurrent, or Metastatic Esophageal Carcinoma

Prior treatment

• Palliative radiation treatment for EC within 4 weeks prior to initiation of study treatment
• Malignancies other than EC within 2 years prior to screening with a negligible risk of metastasis or death adequately treated with expected curative outcome
• Severe infection within 4 weeks prior to initiation of study treatment or any active infection that, in the opinion of the investigator, could impact patient safety
• Prior treatment with CD137 agonists or immune checkpoint blockade therapies, anti-CTLA-4, anti-TIGIT, anti-PD-1, and anti-PD-L1 therapeutic antibodies
• Treatment with any investigational therapy prior to initiation of study treatment
• Prior allogeneic stem cell or solid organ transplantation
• Concurrent participation in another therapeutic clinical trial

Other illness

• Active or history of autoimmune disease or immune deficiency or leptomeningeal disease
• History of idiopathic pulmonary fibrosis, organizing pneumonia, drug-induced pneumonitis, or idiopathic pneumonitis, or evidence of active pneumonitis
• Positive test result for human immunodeficiency virus (HIV)
• Active hepatitis B or hepatitis C

Other

• Evidence of complete esophageal obstruction not amenable to treatment
• Symptomatic, untreated, or actively progressing central nervous system (CNS) metastases
• Uncontrolled tumor-related pain, uncontrolled pleural effusion, pericardial effusion, or ascites requiring recurrent drainage procedures
• Poor peripheral venous access

• Histologically confirmed EC
• Unresectable locally advanced, unresectable recurrent, or metastatic disease
• Measurable disease per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1)
• Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1
• Adequate hematologic and end-organ function
• Female participants must be willing to avoid pregnancy and refrain from donating eggs during the treatment period and for 90 days after the final dose
• Male participants with partners of childbearing potential must commit to the use of two methods of contraception and must not donate sperm for the study duration and 90 days after the final dose