SHR-1210 combined with GEMOX as first-line treatment in patients with advanced biliary tract cancer

535 Background: This study aimed to evaluate the efficacy and safety of SHR-1210 (a humanized anti-programmed cell death receptor 1 antibody) plus gemcitabine and oxaliplatin (GEMOX) as first line treatment in patients (pts) with biliary tract cancer (BTC). Methods: This was a single-arm, single-center, exploratory trial, which included advanced BTC pts. Pts received SHR-1210 (3mg/kg, total dose ≤200mg, ivd, D1/2W) combined with gemcitabine (800 mg/m2, ivd, D1/2W) and oxaliplatin (85mg/m2, ivd, D2/2W). Combined chemotherapy lasted for no more than 12 cycles. Once chemotherapy intolerance occurred or at end of 12-cycle combined chemotherapy, pts with stable disease or objective response would continue to take SHR-1210 as single agent until disease progression or intolerable toxicity. The primary endpoint was the 6-month progression free survival (PFS) rate. Results: From February 2018 to April 2019, 37 eligible pts were enrolled. The median age was 64 (range 41-74) years, male/female was 70.3/29.7%, and bile duct cancer/gallbladder cancer was 59.5/40.5%. All 37 pts were included in the safety analysis. The overall AE incidence rate was 97.3%. The incidence of grade ≥3 AEs was 73.0%, which mainly included increased GGT (gammaglutamyltransferase, 18.9%), hypokalemia (18.9%), and fatigue (16.2%). Particularly, the incidence of fever is 73.0%, in which 2 pts experienced grade 3/4 fever. Among 36 evaluable pts, 19 pts got partial response (PR, 52.8%), 14 pts stable disease (SD, 38.9%), and 3 pts progressive disease (PD, 8.3%) at best. The primary endpoint 6-month PFS rate was 50.0% (95% CI 32.4-65.4), which indicated that the primary endpoint of the study was reached, and mPFS was 6.2 months (95% CI 4.2-7.1). The 12-month overall survival (OS) rate was 50.5% (95% CI 30.6-67.4), and mOS was 12.1 months (95% CI 8.0-NA). Conclusions: This study has reached the pre-defined primary endpoint with a high response rate. Predictive biomarker analysis was reported in another abstract. Further study is needed to validate the efficacy of this combination. Clinical trial information: NCT03486678.