Baseline neutrophil-to-eosinophil ratio and neutrophil-to-lymphocyte ratio as prognostic markers in patients with unresectable biliary tract cancer treated with gemcitabine-cisplatin-durvalumab: an international, multicentre, retrospective cohort study

Background: A combination of gemcitabine, cisplatin and durvalumab (anti-programmed death-ligand 1) is the current standard-of-care first-line therapy for advanced biliary tract cancer (BTC). To date, there is only limited evidence regarding prognostic biomarkers. Studies in other tumour types treated with immune checkpoint inhibitors have highlighted the pretreatment neutrophil-to-eosinophil ratio (NER) and neutrophil-to-lymphocyte ratio (NLR) as potential prognostic biomarkers for response to immunochemotherapy.Our aim is to investigate whether NER and NLR can serve as potential prognostic biomarkers in advanced BTC. Materials and methods: Patient data were retrospectively collected from 39 sites in 11 countries. The study population comprised patients with unresectable, locally advanced, or metastatic BTCs. The primary outcome was overall survival (OS). The secondary outcomes were progression-free survival (PFS) and objective response rate (ORR). Results: A total of 509 patients were included in the analysis. In a multivariate Cox regression model, OS and PFS were significantly shorter for patients with NLR above the median value (OS: hazard ratio (HR) 2.08, 95% confidence interval (CI) 1.44-3.00, P < 0.001 and PFS: HR 1.57, 95% CI 1.17-2.10, P = 0.002). These associations were not found based on NER. There was no significant difference in ORR between patients stratified based on NER or NLR values. Conclusion: A higher baseline NLR was significantly associated with worse PFS and OS. No significant association was found between NER and OS or PFS. These findings suggest that NLR can serve as a prognostic biomarker for patients with advanced BTC treated with gemcitabine-cisplatin-durvalumab.