MUC1 and cancer: Despite extensive efforts for the development of many anti-MUC1 mAbs as potential candidates of anticancer therapeutic reagents for over 30 years,27 to our knowledge, SN-131 is the only antibody that exhibits specific and strong binding affinity with cancer-relevant MUC1 TRD modified by Tn and core 1 type O-glycans such as T and ST antigens at the Asp-Thr-Arg motif.