Adjuvant tislelizumab combined with capecitabine for patients with biliary tract cancer with high risk of postoperative relapse (ACTIVE): Primary analysis from a prospective cohort study.

e16248 Background: Only 20% of biliary tract cancer (BTC) patients are eligible for surgical resection with curative intent, with 5-year overall survival of less than 10% for all patients. This rate is even lower in patients with high-risk features. Capecitabine as an adjuvant therapy in biliary tract cancer has been verified to improve overall survival, however, the efficacy still remains limited. PD-1/L1 antibody combined with chemotherapy have been demonstrated to improve survival in advanced biliary tract cancer. This study aimed to evaluate the efficacy and safety of adjuvant tislelizumab and capecitabine following surgery for biliary tract cancer with high risk of recurrence. Methods: This was a single-center, prospective cohort phase II study. BTC patients (pts) underwent R0/R1 resection with high postoperative recurrence risk were eligible. The high-risk factors included positive resection margins, positive lymph nodes, positive perineural invasion, and tumor > 5cm in diameter. The patients were divided into two groups, the tislelizumab (TIS 200 mg Q3W for 1 year )+capecitabine (CAP D1-14, 1500mg/m 2 for eight 3-weekly cycles) group and the capecitabine group. The primary endpoint was DFS (disease free survival). The second endpoints was OS (overall survival) and adverse event (AE). Results: A total of 37 pts were enrolled into the study, while 22 pts in the TIS+CAP group and 15 in CAP group, 23 males and 14 females with a median age of 66 years. According to the location of the tumor, 37.8% pts were intrahepatic cholangiocarcinoma, 21.6% were gallbladder cancer, 5.4% were distal cholangiocarcinoma and 35.1% were hilar cholangiocarcinoma. The median DFS was 16.2 months (95% CI, 8.1-26.2) in the TIS+CAP group, which was longer than CAP group (11.4 months, 95% CI 4.2-27.1). 12-month RFS rates were 56.5% and 36.6% , respectively. The most common adverse events (AEs, any grade) were rash (18.2%), vomiting (13.6%), neutropenia (13.6%) and anorexia (13.6%) in the TIS+CAP group. Conclusions: Tislelizumab in combination with capecitabine were effective and safe as adjuvant therapy, which can prolong the DFS of BTC patients with high recurrence risk after resection. Clinical trial information: NCT04782804 .