C4B and ovarian cancer: Regarding responses observed to PARP inhibitors in patients with ovarian cancer with detected ATM and CHEK2 alterations, we acknowledge several important caveats: (1) PARP inhibitors demonstrate activity in ovarian cancer independent of DNA damage repair gene mutations; (2) the detected alterations in DNA repair genes may represent CH rather than true somatic mutations; and (3) without matched germline testing or serial variant allele frequency monitoring, we cannot definitively distinguish tumor-derived from CH-derived alterations.