Triple negative breast cancer (TNBC) cell lines with mutation or low expression in HR pathway genes (BRCA1/2 and RAD51) (BT20, CAL51, HCC1806, HCC1395, MDA-MB-436, MDA-MB-468, HCC38)36 (Supplementary Table 4) are more sensitive to CX-5461/CX-3543 (IC50≤10−7 M). Here, RAD51 is linked to breast cancer.