GEM and cancer: To investigate whether MAGEA antigens regulated cancer chemoresistance and tumorigenicity, we first generated tumor organoids from gemcitabine-sensitive (GemS Patient T017 and T018) or -resistant PDAC patients (GemR Patient T020 and T021) respectively (Fig. 2A) and confirmed their sensitivity to Gem in vitro by performing IC50 experiments (Fig. 2B).