CD274 and biliary tract neoplasm: The KEYNOTE-028 trial (NCT02054806), an ongoing, multi-cohort, phase 1b trial to test the efficacy of pembrolizumab in PD-L1 positive solid tumors, released data in the 2015 European Cancer Congress26 on 24 patients with biliary tract cancer (BTC) who had PD-L1 positive tumors.