The report of a single-arm, single-center, retrospective analysis investigating PD-L1 plus chemotherapy as adjuvant therapy in resected biliary tract cancer.

e16322 Background: Biliary tract cancer (BTC) is a heterogeneous group of diseases with dismal prognosis. The TOPAZ-1 phase III trial a survival benefit with the immune checkpoint inhibitor（ICI）plus chemotherapy（GemCis）in patients with advanced BTC. While resection is a potentially curative treatment option for early stage BTC, recurrence rates remain high with current adjuvant treatment (capecitabine or S-1). Inspired by the results of the TOPAZ-1 study, we investigated the effectiveness of durvalumab plus gemcitabine-based chemotherapy as adjuvant therapy in resected BTCs. Methods: This study retrospectively included 21 patients who underwent surgical resection from January 2020 to December 2024 and received durvalumab (1500mg IV, q4w) plus gemcitabine-based chemotherapy as adjuvant therapy in Hepatological Surgery Department of Peking University People’s Hospital. The primary endpoint was recurrence-free survival (RFS). The secondary endpoints included overall survival (OS) and safety. The exploration endpoint was genomic and biomarker analysis. Results: 21 patients received durvalumab with chemotherapy in first line were enrolled in this study. The median age of the cohort was 68 years (range: 36-84 years old), with 42.9% (n = 9) being male and 57.1% (n = 12) female. The majority of patients (47.6%, n = 10) had extrahepatic cholangiocarcinoma, while 23.8% (n = 5) had intrahepatic cholangiocarcinoma, and 28.6% (n = 6) had gallbladder cancer. All patients have had curative surgical treatment, with R0 resection achieved in 85.7% (n = 18) of cases. The chemotherapy included gemcitabine monotherapy (n = 14), Gemox (n = 1), GemCis (n = 3), GemCap (n = 2) and AG (n = 1). The median follow-up was 9.0 months (95% CI 5.88, 14.12). The primary endpoint, recurrence-free survival (RFS), was assessed, with a median RFS of 9 months (95% CI: 7–NA months). The 1-year RFS rates were 35% (95% CI: 16–76%) (Table 1). Overall survival (OS) was a secondary endpoint, with a median OS of 18 months (95% CI: 15–NA months). The 1-year and 2-year OS rates were 82% (95% CI: 63–100%) and 44% (95% CI: 17–100%), respectively (Table 2). No adverse drug reaction has been reported yet. Conclusions: Immunotherapy in combination with chemotherapy offered a promising new option for adjuvant therapy in resected BTCs. These findings warrant further investigation in prospective randomized controlled trials to confirm the efficacy and safety of this combination in the adjuvant setting.