RAD51 and neoplasm: Interestingly, use of this RAD51 foci assay has highlighted that the great majority of responses to PARPi in PDX and clinical samples analysed to date can be explained by the dynamic HRR status of the tumour in a more accurate way than gBRCAm status or HRD scores, with cases with low RAD51 foci counts predicting a better response to treatment than those with high RAD51 foci counts [37,39,40].