BRCA1 and breast cancer: Given the differential response to PARPi in BRCA-mutant TNBC, consistent with previous work,23 we examined the heterogeneity of DNA repair through RNA-sequencing data in The Cancer Genome Atlas.28 To evaluate BRCA-mutant breast cancers, we highlight the BRCA1 or BRCA2 mutants on a background of the other primary tumors of all subtypes from the Breast Cancer cohort of the TCGA dataset.