ESR1 and breast cancer: We tested ONC201 in 17 breast cancer cell lines consisting of different subtypes (4 ER+, 1 ER+/HER2+, 3 HER2+, 4 TNBC Basal A, and 5 TNBC Basal B), and the IC50 range was from 0.78 to 4.83 micromolar without any subtype-specific difference [269].