Real-world outcomes of durvalumab or pembrolizumab plus gemcitabine and cisplatin (GemCis) in advanced biliary tract cancer (BTC).

546 Background: Durvalumab or pembrolizumab combined with GemCis are established first-line treatment for patients with unresectable or metastatic BTC. As patient profiles in daily practice is different from those in prospective trials, we performed the retrospective analysis of patients treated with first-line durvalumab or pembrolizumab plus GemCis. Methods: In this retrospective analysis, 255 patients with histologically or cytologically documented BTC, including intrahepatic and extrahepatic cholangiocarcinoma (CCA) and gallbladder cancer (GBCA), treated with first-line durvalumab (n=210) or pembrolizumab (n=45) plus GemCis for unresectable or metastatic disease between March 6, 2023, and May 16, 2025, were included in this analysis. The primary endpoints were overall survival (OS) and progression-free survival (PFS). Secondary endpoints were objective response rate (ORR) and disease control rate (DCR). Results: The median age was 66 years, and 58.8% were male; 77% of patients had recurrent or metastatic disease while 23% had locally advanced disease. Primary tumor sites were intrahepatic CCA (40.4%), extrahepatic CCA (42.0%), and GBCA (16.5%). In overall patients, median OS was 14.4 months (95% CI, 12.6–16.5), and median PFS was 6.9 months (95% CI, 6.0–8.0). The ORR was 15.3%, and the DCR was 72.5%. In the multivariable analysis, OS was significantly worse in patients with elevated serum CA 19-9 level (HR 1.87 95% 1.11-3.15, p=0.018), GBCA (vs. extrahepatic CCA; HR 1.99 95% CI, 1.10-3.59, p=0.023), and recurrent or metastatic disease (vs. locally advanced; HR 2.50 95% CI, 1.31=4.77, p=0.005). Conclusions: Current analysis demonstrated that the clinical effectiveness of durvalumab or pembrolizumab plus GemCis in real-world practice are consistent in those in pivotal prospective trials.