Antitumor Effects Of Different Administration Sequences Of Apatinib And Cisplatin On Nasopharyngeal Carcinoma

Objective:(1)whether targeted drug apatinib have anti-tumor effect on nasopharyngeal carcinoma;(2)whether apatinib in combination with cisplatin has a synergistic effect on nasopharyngeal carcinoma and how to combination can produce the greatest therapeutic effect.Methods: After the establishment of the 108 nude mice nasopharyngeal carcinoma xenograft model,mice were divided into 6 groups(Eighteen in each):control group(NS0.1ml/d ip d1-7),YN968D1 group(Apatinib 200mg/kg/d ip d1-7),DDP group(DDP 5mg/kg/d ig d1),YN968D1 First group(Apatinib 200mg/kg/d ip d1-7 + DDP 5mg/kg/d ig d8),DDP First group(DDP 5mg/kg/d ig d1 + Apatinib200mg/kg/d ip d2-8),YN968D1+DDP group(DDP 5mg/kg/d ig d1 + Apatinib200mg/kg/d ip d1-7).The animals were sacrificed second days after administration by cervical dislocation.Inhibitory rate of xenograft and tumor growth curve was calculated and plotted for 6 mice each group,immunohistochemical detect the CD31 and VEGFR2,tunel to measure tumor cell apoptosis.6 mice were examined by micro18F-FDG PET/CT to evaluate the therapeutic effect of each group.Survival time was observed in each group for 6 mice.Results: apatinib modestly inhibited the growth of CNE-2xenografted NPC tumors,treatment with a combination of apatinib andcisplatin significantly inhibited tumor growth and more so than that obtained by the two drugs administered alone(p<0.05).Treatment with YN968D1 + DDP resulted in the most significant inhibition of tumor growth of all regimens,as determined by tumor volume(P < 0.05).Treatment administered as per the regimens of the YN968D1,DDP,YN968D1 first,DDP first,and YN968D1 +DDP groups inhibited tumor weights by 15,31,46,53,and 70%,respectively.The Q index of treatment with YN968D1 + DDP combined was 1.69,which indicated a synergetic effect when the drugs were administered simultaneously.The median survival time of control mice was 41 days.There was no significant difference in the median survival time of mice treated with YN968D1(60 days)and DDP(67 days;P = 0.17),though these regimens significantly prolonged the median survival time over controls.Tumor-bearing mice treated with YN968D1 or DDP(first groups)had a longer median survival time over standalone treatments(69 and 71 days,respectively),though there was no significant difference between these regimens.Treatment with YN968D1 and DDP combined resulted in the greatest survival time(88 days)of all treatment regimens.Whilst tumors of mice treated with control or DDP were overwhelming positive,those treated with YN968D1 + DDP had only marginal staining.The percentage of VEGFR-2-positive cells of mice treated by Apatinib(54.50%)was markedly less than the control(92.83%;P < 0.05)and cisplatin groups(88.16%;P < 0.05).There was no significant difference in the VEGFR2 positivity of tumors treated with either control or cisplatinregimens(P > 0.05).Tumors treated with YN968D1 + DDP had the lowest proportion of VEGFR-2-positive cells of all treatment regimens(8.83%;P <0.05).Immunohistochemical staining of xenografted CNE-2 NPCs with a VEGFR-2 antibody label from D0,D5,D10,D15 revealed the activity of VEGFR-2(Figure 4).The expression of VEGFR-2 in D0 and D15 groups were overwhelming positive,the percentage of VEGFR-2-positive cells between those two groups was no significant difference(85.83%,75.50%;P > 0.05).There was no significant difference in the VEGFR-2 positivity of tumors between the D5(61.67%)and theD10(64.33%;P>0.05),the percentage of VEGFR-2-positive cells of those two groups were also no significant difference between D15 groups(P > 0.05),but siginificant lower than the D0group(P < 0.05).The MVD within tumors of control mice(8.67)was markedly greater than that of tumors treated with all other regimens(P < 0.01).Tumors treated with YN968D1 + DDP group had the lowest MVD(1.17)of all regimens,especially comparied with the control group and DDP group(P <0.01).There was no significant difference in the MVD of xenografts treated with YN968D1(5.00),YN968D1 first(4.33),and DDP first(4.00).Tumor xenografts treated with various regimens underwent TUNEL analysis for the determination of apoptotic cells.Positively-stained nuclei of apoptotic cells were sporadic within tumors of control mice and those treated with standalone regimens,whilst an increased frequency of positively-stained nuclei were observed in tumors treated with YN968D1 + DDP(34.67).The number ofapoptotic cells was significantly lower in the control group(1.67)over all other groups(P < 0.05).Compared with the control and single treatment groups,combined treatment-particularly within the YN968D1 + DDP group-significantly increased the apoptosis of murine xenograft cells(P < 0.05).Xenografted mice underwent micro18F-FDG PET/CT imaging one-day post completion of treatment as to discern the tumors early response to the various drug regimens(Figure 7).The metabolism of tumors treated with the control regimen was significantly higher than that of the other regimens(P<0.05),whilst the metabolic signal of tumors treated according to the YN968D1 + DDP regimen was notably low(P<0.05).The T/M associated with both treatment regimens was significantly lower than that of controls(2.35;P<0.05).The T/M associated with tumors treated with YN968D1 + DDP was significantly lower than all other treatment regimens(1.06;P < 0.05).These results suggest that the NPC xenografts responded most favorably to treatment with YN968D1 + DDP.Conclusion:(1)Apatinib has anti-tumor effect on nasopharyngeal carcinoma;The anti-angiogenesis effect for apatinib in the treatment of nasopharyngeal carcinoma is mainly through reduce the expression of VEGFR-2.(2)YN968D1+DDP group has a synergistic effect,resulting in 1+1>2.