CD274 and gastric cancer: Based on the observation that the two 5FU-resistant cell lines showed increased levels of PD-L1 compared to their parental cell lines, we examined whether PD-L1 could be a prognostic factor for GC patients who underwent gastrectomy followed by S-1 adjuvant chemotherapy using the Northern Japan Gastric Cancer Study patient cohort (23, 24, 25).