Background  Neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) are associated with the prognosis of some solid tumors after immunotherapy, however, its single or combined prognostic value in bile tract carcinoma (BTC) is not clear.

  Objective  To explore the relationship between NLR, PLR or their combination (CNP) and prognosis of patients undergoing BTC immunotherapy.

  Methods  Patients with BTC treated in the First Medical Center of Chinese PLA General Hospital from January 2017 to April 2021 were included, and peripheral blood related indicators of patients with more than 2 cycles of PD-1 inhibitors were collected. Pre-treatment NLR and PLR were calculated by division of neutrophils and platelets by lymphocytes measured in peripheral blood. The ROC curve was used to obtain the optimal cut-off values of them. The optimal Cut-off value of NLR was 2.295, and PLR was 147.954. According to NLR and PLR, the patients were divided into high CNP (PLR＞147.954 and NLR＞2.295, n=36), median CNP (PLR＞147.954 or NLR＞2.295, n=26) and low CNP (PLR≤147.954 and NLR≤2.295, n=22) groups. K-M analysis and Cox regression analysis were conducted to study the prognostic role of NLR, PLR and CNP. Results A total of 84 patients with BTC were enrolled, including 48 males and 36 females with a median age of 59.5 years. After immunotherapy, 2 patients achieved CR, 11 patients achieved PR, and 32 patients achieved SD, with an overall ORR of 15.5% and disease control rate (DCR) of 53.5%. Immune-related adverse effects occurred in 17 cases. High NLR group was associated with shorter PFS (10 months vs 5 months, P＜0.001) and lower DCR (42.8% vs 65.8%, P=0.028), and high PLR group was also associated with shorter PFS (9 months vs 4 months, P＜0.001) and lower DCR (45.4% vs 68.9%, P=0.040). Median survival (10 months vs 6 months, P＜0.001) and disease response rate (69.2% vs 43.5%, P＜0.001) were significantly better than the other two groups when both NLR and PLR were lower than the cut-off value.

  Conclusion  For patients with BTC treated with PD-1 inhibitors, patients with NLR＜2.295 or PLR 147.954 are more likely to benefit from immunotherapy.