ESR1 and breast cancer: Results from the BOLERO-2 and TAMRAD clinical trials showed that the addition of everolimus to either exemestane or tamoxifen was associated with longer progression-free survival (PFS) compared to either exemestane or tamoxifen alone in ER+ advanced breast cancer patients who had progressed on an aromatase inhibitor (AI) (BOLERO-2, PFS 7.8 vs. 3.2 months, p < 0.0001; TAMRAD, PFS 8.6 vs. 4.5 months, p < 0.01) [31,43].