Intracellular Pharmacokinetics And In Vivo Efficacy Of "ZD2767P-CPG2-US" Against Cisplatin Resistant Ovarian Cancers

BackgroundCiaplatin(DDP)is the first-line agent for certain cancers,such as ovarian and non-small cell lung cancers.The therapeutic efficacy was decreased with acquire of chemoresistance,and therefore new strategies are urgently needed.ZD2767P–CPG2 is a prodrug–enzyme strategy,where the activie molecule is ZD2767D.ZD2767P–CPG2 has been limited by toxicity to non-cancerous tissues;further,pharmcokinitic(PK)of ZD2767D remains unclear.Ultrasound can permenbilze the vessels and cell membranes,thereby adjusting intratumoral and intracellular PK.Thus,ultrasound is introduced to ZD2767P–CPG2 to develop ZD2767P–CPG2–US.Preliminary data have demonstrated that ZD2767P–CPG2–US can deactivate DDP-resistant human ovarian/lung cancer cells,and is effective against subcutaneous xenogafts of ovarian cancer.ObjectivesTo explore the intracellular PK of ZD2767P–CPG2–US,and to determine the in vivo efficacy on orthotopic ovarian tumors in nude mice.Methods1.A spectrophotometry was established to simultaneously detect ZD2767P and ZD2767D in lysates,and then intracellular PK was explored.C_max,AUC_last,MRT_lastand the percentage of cellular uptake were calculated.2.Alkaline and neutral comet assays were performed to detect DNA break.3.An orthotopic tumor model was established in nude mice,using SKOV3 and SKOV3/DDP cells.The survival time was followed after treatments.4.Safety was investigated in a subcutaneous tumor model.Blood cell counts,biochemical hepatic/renal fuctions,and body mass were measured 2and 14 days after treatments.Results1.The double-wavelength spectrophotometry can simultaneously determine ZD2767P and ZD2767D in cell lysates.2.Intracellular PK of ZD2767D.SKOV3&SKOV3/DDP:C_max,AUC_last,and MRT_lastin the ZD2767P+CPG2+US group were higher than those in the ZD2767P+CPG2 group(1.6-to 2.0-fold for C_max,p<0.0001 to0.0193;1.8-to 3.6-fold for AUC,p<0.0001 to 0.0172;1.2-to 1.9-fold for MRT,p<0.0001 to 0.0110);a higher cell-uptake fraction was noted in the ZD2767P+CPG2+US group(6.1-8.4%vs.3.6-5.2%,p<0.0001 to0.0236).Intracellular PK of ZD2767D was nonproportional.A549&A549/DDP:C_max,AUC_lastand MRT_lastin the ZD2767P+CPG2+US group were higher than those in the ZD2767P+CPG2group(1.6-to 2.0-fold for C_max,p=0.0006-0.0382;1.8-to 3.5-fold for AUC,p<0.0001 to 0.0066;1.1-to 1.9-fold for MRT,p<0.0001 to0.0274);a higher cell-uptake fraction was noted in the ZD2767P+CPG2+US group(6.4-8.7%vs.3.7-4.5%,p=0.0003-0.0293).PK of ZD2767D was proportional in the ZD2767P+CPG2 group,but was nonproportional in the ZD2767P+CPG2+US group.3.A549 and A549/DDP:alkaline and neutral comet assays indicated that ZD2767P+CPG2 and ZD2767P+CPG2+US induced comet formation,with a higher comet-formation percentage in the latter group(p<0.0001 in A549,p<0.0001 in A549/DDP).DDP-sensitive and-resisitant cells had similar comet percentages.The neutral comet percentage approached to the alkaline comet percentage.4.Compared with the control group,a longer mean survival time was noted in the ZD2767P+CPG2 and ZD2767P+CPG2+US groups in SKOV3-(33.0±3.5 or 39.2±1.8 vs.25.0±1.6 days,p<0.0001)and SKOV3/DDP-derived tumors(16.2±4.8 or 22.3±7.3 vs.8.7±3.9 days,p=0.0015);the longest time was observed in the ZD2767P+CPG2+US group.5.No severe adverse events were observed in mice in the ZD2767P+CPG2 and ZD2767P+CPG2+US groups.Conclusions1.ZD2767P+CPG2+US modulated the intracellular PK of ZD2767D,leading to higher C_max,AUC_last,MRT_lastand cell-uptake percentage.2.ZD2767P+CPG2+US can directly induced DNA double-strand break.3.ZD2767P+CPG2+US was effective in vivo,prolonging the survival time in mice bearing orthotipic ovarian tumors.4.ZD2767P+CPG2+US had good tolerance in vivo.