Based upon the data from the PROfound trial, in May 2020 the FDA approved olaparib (300 mg twice daily) for oral use in patients with mCRPC progression following treatment with enzalutamide or abiraterone, irrespective of prior taxane-based therapy, and carrying a germline or somatic alteration in an HRR gene, determined on a positive test from tumor tissue (ATM, BRCA1, BRCA2, BARD1, BRIP1, CDK12, CHEK1, CHEK2, FANCL, PALB2, RAD51B, RAD51C, RAD51D, or RAD54), lymphocytes from blood (germline testing for BRCA1 or BRCA2), or plasma using a circulating tumor DNA assay (ATM, BRCA1, BRCA2). The gene discussed is CHEK1; the disease is neoplasm.