The data from several studies demonstrated that integrating somatic PV of BRCA1/2, silencing methylations of BRCA1 promoters, along with alteration of other genes of the HR pathway such as PALB2, ATM, or CHEK2 may help to identify additional patient candidates for PARPi, representing up to 20% of patients with ER+/HER2- breast cancer. Here, CHEK2 is linked to breast cancer.