CD274 and biliary tract cancer: Interim safety and efficacy data have been reported for a small cohort of patients with PD-L1-positive biliary tract cancer; 37 of 89 patients screened (41.6%) had PD-L1 expression on ≥1% of tumor cells by immunohistochemistry, 24 of whom enrolled in the study (20 with CCA, four with gallbladder carcinoma) [101] Pembrolizumab 10 mg/kg was given every two weeks for up to two years or until confirmed progression or unacceptable toxicity.