Soon after discovering CD318 (CDCP1) as the second ligand of CD6 [6], we demonstrated that interrupting the CD6-CD318 axis with a single dose of UMCD6 enhances the capacity of human PBMC (peripheral blood mononuclear cells) to kill CD318 + breast, prostate and lung cancer cells in vitro, and breast cancer cells in vivo [7]. This evidence concerns the gene CD6 and breast cancer.