While the authors are not aware of any study examining a complete panel of HRD patients with ICIs, several groups have studied patient populations with a mutation in a select HRD gene/gene set, including MMR, BRCA1/2, POLD1 or POLE, MUTYH, and ERCC1. Studies in the MMR and BRCA1/2 populations include ovarian cancer patients, and the POLD1/POLE and MUTYH groups included other gynecologic cancers (endometrial). The gene discussed is MRC1; the disease is ovarian cancer.