Suppression of WHIM20 tumor growth was even greater when SI-2 was administered in combination with an oral SERD, AZD9496, compared to either single agent alone, suggesting that targeting coactivator recruitment in combination with endocrine therapy could be a promising therapeutic strategy for breast tumors harboring ESR1 LBD mutants such as Y537S and D538G[66]. This evidence concerns the gene ESR1 and breast neoplasm.