Tiragolumab plus atezolizumab and chemotherapy as first-line treatment for patients with unresectable oesophageal squamous cell carcinoma (SKYSCRAPER-08): a randomised, double-blind, placebo-controlled, phase 3 trial.	BACKGROUND: There is an unmet need for additional and more efficacious therapies for patients with unresectable metastatic oesophageal cancer. We aimed to evaluate the efficacy and safety of adding tiragolumab and atezolizumab to chemotherapy as first-line treatment for unresectable or metastatic oesophageal squamous cell carcinoma. METHODS: The SKYSCRAPER-08 randomised, double-blind, placebo-controlled, phase 3 trial was done at 67 centres in mainland China, South Korea, Thailand, Taiwan, and Hong Kong and enrolled adult patients (aged ≥18 years) with treatment-naive, unresectable locally advanced, unresectable recurrent, or metastatic oesophageal squamous cell carcinoma, with an Eastern Cooperative Oncology Group performance status of 0-1. Patients were randomly assigned (1:1) to receive tiragolumab (600 mg) plus atezolizumab (1200 mg) and chemotherapy (paclitaxel [175 mg/m(2)] and cisplatin [60-80 mg/m(2)]) or placebo and chemotherapy through intravenous infusion for six 21-day cycles. The primary outcomes were independent review facility-assessed progression-free survival and overall survival in the intention-to-treat population (defined as all randomly assigned patients, regardless of whether they received any study treatment). This study was registered with ClinicalTrials.gov, NCT04540211, and is ongoing. FINDINGS: Between Oct 30, 2020, and Nov 30, 2021, 461 patients were assigned to receive tiragolumab plus atezolizumab and chemotherapy (n=229) or placebo and chemotherapy (n=232); 406 (88%) were male and 55 (12%) female, and all patients were Asian. Median survival follow-up was 12·6 months (IQR 6·8-18·0). Median independent review facility-assessed progression-free survival (cutoff June 15, 2022) in the tiragolumab plus atezolizumab and chemotherapy group was 6·2 months (95% CI 5·7-7·2) versus 5·4 months (95% CI 4·4-5·5) in the placebo and chemotherapy group (HR 0·56, 95% CI 0·45-0·70; p<0·0001). Median overall survival (cutoff Feb 13, 2023) was 15·7 months (95% CI 13·3-20·4) and 11·1 months (95% CI 9·6-13·6; HR 0·70, 95% CI 0·55-0·88; p=0·0024). The most common grade 3-4 adverse events in the tiragolumab plus atezolizumab and chemotherapy group versus the placebo and chemotherapy group were white blood cell count decrease (46 [20%] of 228 vs 35 [15%] of 227), neutrophil count decrease (78 [34%] vs 78 [34%]), and anaemia (19 [8%] vs 24 [11%]). Serious adverse events occurred in 94 (41%) of 228 patients in the tiragolumab plus atezolizumab and chemotherapy group and 89 (39%) of 227 in the placebo and chemotherapy group; the most common serious adverse event was pneumonia (17 [7%] of 228 and 13 [6%] of 227). Treatment-related deaths occurred in six patients (3%) in the tiragolumab plus atezolizumab and chemotherapy group (immune-mediated lung disease, pneumonitis, cardiac arrest, gastrointestinal haemorrhage, hepatic failure, and bacterial pneumonia) and two (1%) in the placebo and chemotherapy group (gastrointestinal infection and death of unknown cause). No new safety signals were identified. INTERPRETATION: Independent review facility-assessed progression-free survival and overall survival were significantly better in the tiragolumab plus atezolizumab and chemotherapy group compared with chemotherapy alone for unresectable locally advanced, unresectable recurrent, or metastatic oesophageal squamous cell carcinoma. These data support the rationale for exploring dual checkpoint inhibition added to chemotherapy for this group of patients with a high unmet need. FUNDING: F Hoffmann-La Roche-Genentech.	esophagus