Effect of triplet regimen (single-agent chemotherapy plus anti-PD-1 antibody and tyrosine kinase inhibitors) on survival compared to chemotherapy in the second-line treatment of advanced biliary tract cancer: A retrospective analysis.

e16132 Background: TOPAZ-1 and KEYNOTE-966 trials have demonstrated the survival benefit of immune checkpoint inhibitors (ICIs) plus chemotherapy in advanced biliary tract cancer (BTC). Although the ABC‐06 study proved the benefits of FOLFOX in 2nd line therapies, the efficacy is limited. There is no consensus regarding the optimal therapy regimen, and more effective therapeutic options are needed. This retrospective analysis aims to evaluate the efficacy of a triplet regimen compared to standard chemotherapy in 2nd line BTC. Methods: Pts > 18 years, with ECOG PS 0/1, histologically confirmed metastatic BTC and progression on 1 st line Gemcitabine-based therapy were eligible. A triple regimen was referred as Cohort A: tislelizumab and other anti-PD-1 antibody, capecitabine or S-1 plus tyrosine kinase inhibitors (TKIs, lenvatinib or anlotinib). Standard chemotherapy was Cohort B: mFOLFOX or irinotecan plus capecitabine. Primary endpoint was progression-free survival (PFS). Secondary endpoints were overall survival (OS), overall response rates (ORR), disease control rate (DCR) and safety. Results: This study retrospectively collected and analyzed treatment and clinical information from 121 pretreated BTC pts from Oct. 2021 to Oct. 2023, with a median age of 60 (range 36-82) years and 48% (58) of the pts were female. Among them, 86 patients received the triple regimen, while 35 patients received standard chemotherapy. Pts’characteristics were well balanced between the two groups in terms of gender, age, ECOG score, primary site, CEA, CA199, or presence of distant metastasis. According to the RECIST1.1 criteria, 1 pt achieved CR and 31 pts had PR in the triple treatment cohort, ORR reached 37.2% (95%CI 27.0-48.3%), which was significantly higher than the 2.8% (95%CI 0.1-14.9%) in the standard chemotherapy cohort (p < 0.0001). Accordingly, the DCR of the two groups were 89.5% (95%CI 81.1-95.1%) and 71.4% (95%CI 53.7-85.4%) respectively. As of Oct 31, 2023, all patients developed progression, and the median PFS in cohort A was 6 months, compared to 2.0 months in cohort B (HR, 0.29, 95%CI 0.16-0.52, p < 0.0001). 64 patients of cohort A and 28 patients of cohort B developed death. The median OS in cohort A was 16.0 months, compared to 6.0 months in cohort B (HR 0.35, 95%CI 0.19~0.64, p < 0.0001). Any grade TRAEs occurred in 54.7% pts of cohort A and 42.9% of cohort B. Most common grade 3 TRAEs were hypohepatia (19.8%), hand-foot syndrome (11.6%), gastrointestinal reaction (1.2%) in cohort A, and hypohepatia (8.6%), hand-foot syndrome (2.9%) in cohort B. Conclusions: The retrospective analysis suggests that the triple regimen as second-line treatment for advanced BTC pts may help improve the efficacy and survival, and is worthy of further prospective exploration.