ESR1 and breast cancer: While ERX-41 (Extended Data Fig. 1c) was incrementally more potent than ERX-11 (IC50 100–125 nM versus 200–500 nM) in ER-α+ BC, its potency in TNBC was enhanced (>100-fold) from IC50 >10 μM to 100 nM (Extended Data Fig. 1c).