Next, to determine whether resistance to PARP inhibitors might be explained by pharmacokinetic/pharmacodynamic (PK/PD) reasons, and whether this might correlate with the increase in mesenchymal features in resistant tumours, we analyzed olaparib concentration in tumours from four cohorts of mice (Figure 9A): olaparib-naïve mice, taken 1 or 24 hours after a single dose of 100 mg/kg olaparib, and those in which tumours had become resistant to olaparib, taken 1 or 24 hours after a final dose of IP 100 mg/kg olaparib. This evidence concerns the gene PARP1 and neoplasm.