Fig. 2From: The role of patient-derived ovarian cancer organoids in the study of PARP inhibitors sensitivity and resistance: from genomic analysis to functional testingAcquired resistance to PARPi can develop via three general mechanisms: restoration of HRR owing to (i) revertant mutations, (ii) demethylation of BRCA1 promoter or (iii) regulation of DNA end resection and cell cycle; replication fork protection; and drug target-related effects, such as (i) upregulation of drug efflux pumps or (ii) phosphorylation of PARP1Back to article page