Consequently, new complete antiestrogens are being examined for their activities in breast cancers harboring Y537S and D538G ERα that all demonstrate improved oral bioavailability and pharmacokinetics, including G1T48, AZD9496, GDC-0927, RAD1901, SAR439859, and LSZ102 (Wardell et al., 2017; De Savi et al., 2015; Weir et al., 2016; Toy et al., 2017; Dickler et al., 2018; Wardell et al., 2015b; Bihani et al., 2017; Tria et al., 2018; Shomali et al., 2017). This evidence concerns the gene ESR1 and breast cancer.