Efficacy and Safety of Pembrolizumab in Patients with RefractoryAdvanced Biliary Tract Cancer: Tumor Proportion Score as a PotentialBiomarker for Response / Journal of the Korean Cancer Association, 대한암학회지

ABSTRACT

Purpose@#The current standard chemotherapy for advanced biliary tract cancer (BTC) has limited benefit,and novel therapies need to be investigated. @*Materials and Methods@#In this prospective cohort study, programmed death ligand-1 (PD-L1)–positive BTC patientswho progressed on first-line gemcitabine plus cisplatin were enrolled. Pembrolizumab 200mg was administered intravenously every 3 weeks. @*Results@#Between May 2018 and February 2019, 40 patients were enrolled. Pembrolizumab wasgiven as second-line (47.5%) or  third-line therapy (52.5%). The objective response ratewas 10% and 12.5% by Response Evaluation Criteria in Solid Tumor (RECIST) v1.1 andimmune-modified RECIST (imRECIST) and median duration of response was 6.3 months.Among patients with progressive disease as best response, one patient (1/20, 5.0%)achieved complete response subsequently. The median progression-free survival (PFS) andoverall survival (OS) were 1.5 months (95% confidence interval [CI], 0.0 to 3.0) and 4.3months (95% CI, 3.5 to 5.1), respectively, and objective response per imRECIST was significantlyassociated with PFS (p < 0.001) and OS (p=0.001). Tumor proportion score  50%was significantly associated with higher response rates including the response after pseudoprogression(vs. < 50%; 37.5% vs. 6.5%; p=0.049). @*Conclusion@#Pembrolizumab showed modest anti-tumor activity in heavily pretreated PD-L1–positiveBTC patients. In patients who showed objective response, durable response could beachieved.