Similarly, concurrent use of everolimus with exemestane or trastuzumab plus vinorelbine in breast cancer patients, who are resistant to aromatase inhibitors or trastuzumab respectively, have led to significant improvement in PFS, indicating that reducing mTOR activity is useful against chemoresistance in breast cancer (Baselga et al., 2012; André et al., 2014). This evidence concerns the gene CYP19A1 and breast cancer.