ESR1 and cancer: Therefore, newly developed mixed SERM/SERDs and SERDs with improved pharmacokinetics and oral bioavailability over fulvestrant, such as AZ9496, bazedoxifene, GDC910, and RAD1901, should be particularly effective against cancers expressing the Y537S and D538G ESR1 mutants (De Savi et al., 2015; Garner et al., 2015; Lai et al., 2015; Wardell et al., 2013).