Evaluation of safety and tolerability of durvalumab (D) with or without tremelimumab (T) in patients (pts) with biliary tract cancer (BTC).

387Background: This Phase 1 study (NCT01938612) evaluated D (anti-PD-L1 mAb) and T (anti-CTLA-4 mAb) in Asian pts, in whom optimal dosing of D and T is undetermined. No dose-limiting toxicities were observed, and durable responses were seen in a dose escalation phase evaluating various D doses and regimens in Japanese pts (Iguchi, ASCO 2015). The study was subsequently expanded to larger cohorts of Asian pts with advanced solid tumors including BTC. Methods: Two regimens were selected for the expansion phase: D monotherapy (10 mg/kg q2w) and D+T (D 20 mg/kg + T 1.0 mg/kg q4w). One cohort of pts with advanced BTC was enrolled to receive D monotherapy followed by a separate cohort that received D+T with additional pts enrolled if efficacy was observed. Safety, response, and survival endpoints were based on investigator assessment. Results: Pts were enrolled to D (N = 42) or D+T (N = 65). Median age was 64 years for the D cohort and 62 years for the D+T cohort, the majority were male, and ECOG PS was 0 or 1:...