Poly (ADP-ribose) polymerase (PARP) inhibitors are approved for the treatment of breast cancer susceptibility genes 1 and 2 (BRCA1/2) mutant ovarian and breast cancers, and are now being evaluated in metastatic castration-resistant prostate cancer (mCRPC). | Polyclonal BRCA2 mutations following carboplatin treatment confer resistance to the PARP inhibitor rucaparib in a patient with mCRPC A case report