MUC1 and breast cancer: In addition, a recent phase I/II clinical trial (NCT04430595) has been designed to investigate the safety and feasibility of HER2-, disialoganglioside (GD2)-, CD44v6- specific CAR-T cells (4SCAR T cells) in subjects with breast cancer, as well as one more recent phase 1 trial (NCT04020575) has emphasized on using mucin (MUC)- targeting CAR-T cells (huMNC2-CAR44 cells) in advanced MUC1+ breast cancer.