Tislelizumab in combination with chemotherapy for the treatment of Chinese patients (pts) with esophageal squamous cell carcinoma (ESCC): Results from one cohort of an ongoing phase 2 study.

14Background: Tislelizumab, a humanized IgG4 mAb with high affinity and specificity for PD-1, is specifically engineered to minimize binding to FcγR on macrophages, thereby abrogating antibody-dependent phagocytosis, a potential mechanism of T-cell clearance and resistance to anti-PD-1 therapy. This phase 2 study assessed the safety and tolerability of tislelizumab combined with chemotherapy as first-line therapy in pts with gastric cancer and ESCC; the results of the ESCC cohort are presented here. Methods: Chinese pts with inoperable, locally advanced ESCC were treated with tislelizumab (200 mg IV Q3W), cisplatin (80 mg/m² IV Q3W for up to six cycles), and fluorouracil (800 mg/m²/d, days 1-5 IV Q3W for up to six cycles). Safety/tolerability of the combination regimen was assessed by monitoring adverse events (AEs) per NCI-CTCAE v4.03 criteria. Results: As of 13 June 2018, 15 pts (median age, 61 yrs; male/female, 14/1) were enrolled. The median treatment duration was 108 days (range 21-201). The mean (Q1...