LSD1/ER-IN-1 (compound 11g) is a potent ER and LSD1 inhibitor, with an IC 50 of 1.55 μM ( LSD1 ). LSD1/ER-IN-1 has high affinity selectivity for ERα protein, with α/β ratio of 7.11. LSD1/ER-IN-1 shows good antiproliferative activity against MCF-7 breast cancer cells, with an IC 50 of 8.79 μM.