Efficacy and safety of camrelizumab combined with chemotherapy in the treatment of advanced biliary malignancy and associations between peripheral blood lymphocyte subsets and clinical outcomes

Biliary tract cancer (BTC) is a highly heterogeneous aggressive tumor, and advanced patients have poor prognosis. This work aimed to evaluate the efficacy and safety of camrelizumab combined with chemotherapy in treating advanced BTC, and to explore predictive biomarkers for distinguishing effective population.

183 advanced BTC patients admitted from September 2018 to September 2021 were retrospectively selected. 93 patients were treated with camrelizumab combined with chemotherapy (C+C group) and 90 patients were treated with chemotherapy alone (C group). Objective response rate (ORR), disease control rate (DCR), median progression-free survival (mPFS), and median overall survival (mOS) were analyzed between two groups. Peripheral blood lymphocyte subsets were assessed by flow cytometry pre- and post-treatment.

The mPFS (6.9 months) and mOS (12.1 months) in the C+C group were significantly longer than those in the C group, which were 5.2 months and 9.8 months respectively (HR 0.46, 95% CI 0.38–0.54, p=0.017; HR 0.39, 95% CI 0.32–0.47, p=0.033). The percentage of Total T, CD4+T, natural killer (NK) cells, lymphocyte, and CD4+/CD8+ cell ratios were significantly increased in effective patients after C+C treatment, but didn’t increase in progressive disease (PD) patients. Higher percentage of Total T, CD4+T, and higher CD4+/CD8+ cell ratios post-treatment were associated with longer OS.

Camrelizumab combining chemotherapy significantly prolonged the mPFS and mOS of advanced BTC patients. Immunotherapy may improve the immune status of advanced patients, and immunotherapy efficacy might be predicted based on the peripheral blood lymphocyte subsets.