A previous study demonstrated that immune cells such as CD8+ lymphocytes induce epithelial to mesenchymal transition of BCSCs [8] Moreover, the tumor microenvironment (TME) promotes BCSC survival and cancer progression [9], and hence it can prevent the success of immunotherapy [10] The use of combination therapy, in which both chemotherapy and natural compounds are used to target metastatic BCSCs (mBCSCs), could be a successful approach to overcome chemoresistance and achieve clinical success in treating breast cancer. The gene discussed is CD8A; the disease is breast carcinoma.