Yet, in breast cancer, definitive evidences are still lacking that BRCAness-associated breast cancer may respond to PARP inhibitors and a specific clinical trial is ongoing in France, testing whether rucaparib might be effective in advanced breast cancer without BRCA1/2 germline mutation but either LOH or somatic BRCA1/2 mutation as determined on metastatic tissue (Ruby trial, NCT02505048). Here, BRCA1 is linked to breast cancer.