BRCA1 and neoplasm: To understand how prolonged PARPi treatment reshapes BRCA1/2-deficient tumors, we performed whole-exome sequencing (WE-seq), low-coverage whole-genome sequencing (LCWG-seq), and RNA sequencing (RNA-seq) on the collection of matched PARPi-naive and PARPi-resistant KB1P(M) and KB2P tumors and identified alterations specific to each resistant tumor compared with the matched naive tumor.