Animal Experiments And Preliminary Clinical Translational Studies On ^99mTc-3PRGD₂ SPECT Imaging For Diagnosis And Efficacy Evaluation Of Pancreatic Cance

Part Ⅰ Basic study and preliminary clinical transformation of integrin receptor imaging in the diagnosis of pancreatic cancerPurpose:Early diagnosis and treatment of pancreatic cancer is a difficult point in clinical practice.It is in urgent need of early diagnosis and early efficacy evaluation.Integrin αvβ 3plays an important role in tumor angiogenesis and metastasis.Radionuclide labeled RGD（Arg Gly ASP）polypeptide can interact with integrinα_vβ₃ specific binding,which is expected to be used for integrin α_vβ₃ imaging and treatment of positive tumors.99mTc-HYNIC-3PEG4-E[c（RGDfK）]2（99m Tc-3PRGD2）targeting integrin α_vβ₃ has been applied in the diagnosis of some malignant tumors,but has not been reported in the diagnosis and treatment of pancreatic cancer.In our study,99m Tc-3PRGD2 SPECT was first applied to the diagnosis of pancreatic cancer in tumor bearing mice and clinical transformationMethod:Integrin α_vβ₃ staining of pancreatic cancer cells and tumor tissues to determine whether they are expressed.PANC-1 pancreatic cancer cells were implanted into the shoulder of BALB/C nude mice,and a qualified animal model was established.99mTc-3PRGD2 was prepared with hydrazine nicotinamide（HYNIC）as bifunctional linker.99mTc-3PRGD2 scintigraphy was performed every 0.5 hours to observe the wholebody distribution.The region of interest（ROI）of tumor（T）and contralateral corresponding site（NT）was delineated,and the ratio of radioactivity（T/NT）was calculated.99mTc-3PRGD2 SPECT examination was performed in 11patients with space-occupying lesions of the pancreas to evaluate the detection rate of pancreatic cancer.The differences between the treatment groups were evaluated by two-way repeated measurement analysis of variance（ANOVA）.Quantitative and semiquantitative data were expressed as the mean ±SD and analyzed by using Prism 9.0（GraphPad,San Di-ego,California）and SPSS version 19.0（IBM,Chicago,IL,USA）.Student t-test or one-way ANOVA were used to compare the data differences between groups.Result:Integrin α_vβ₃ it was highly expressed in pancreatic cancer cells and tumor tissues.The labeling rate of 99mTc-3PRGD2 was greater than 99%.The imaging of tumor bearing mice showed that the tumor uptake of tracer was high,and the tumor could be seen within 0.5h p.i.,the T/NT reached the maximum within 1.5h p.i.,and the tumor could be clearly displayed within 6h.99mTc-3PRGD2 SPECT could detect primary pancreatic lesions and metastasis in 10patients,and the detection rate was 100%.Conclusion:99mTc-3PRGD2 imaging is very sensitive to the detection of pancreatic cancer.It is worthy of further study of 99mTc-3PRGD2 as a new clinical tracer for integrin receptor imaging.With 99mTc-3PRGD2 scintigraphic imaging,the tumor response to antiangiogenic therapy,chemotherapy,and the combined treatment can be observed at an early stage of the treatments,much earlier than the tumor volume change.It provides new opportunities for developing individualized therapies and dose optimization.Part Ⅱ Experimental study of integrin receptor imaging in the evaluation of anti neovascularization effectPurpose:The five-year survival rate of patients with pancreatic cancer is low.The main reasons include low early detection rate,rapid progress,the development of drug resistance and the lack of appropriate treatment.We applied endostar,a domestic anti angiogenesis drug,to the treatment of pancreatic cancer for the first time,and 99mT c-3PRGD2 SPECT,together with gemcitabine---a pancreatic chemotherapy drug,to the diagnosis of pancreatic cancer and to monitor the early efficacy of antiangiogenesis therapy,so as to evaluate its potential value in the diagnosis and treatment of pancreatic cancer.Method:The nude mice models of pancreatic cancer were divided into 4 groups randomly,3 treatment group and 1 control group,7 tumor bearing mice in each group.They were treated in different groups with 10 mg/kg/day of endostar,10 mg/kg/day of gemcitabine,10 mg/kg/day of endostar+10 mg/kg/day of gemcitabine at the same time,and the control group with 0.9%saline（0.1 ml/day）.99mTc-3PRGD2 scintigraphic imaging was carried out to monitor therapeutic effects.Microvessel density（MVD）was measured using immunohistochemical staining of the tumor tissues.The region of interest（ROI）of tumor（T）and contralateral corresponding site（NT）was delineated,and the ratio of radioactivity（T/NT）was calculated.The differences between the treatment groups were evaluated by two-way repeated measurement analysis of variance（ANOVA）.Quantitative and semiquantitative data were expressed as the mean ±SD and analyzed by using Prism 9.0（GraphPad,San Di-ego,California）and SPSS version 19.0（IBM,Chicago,IL,USA）.Student t-test or one-way ANOVA were used to compare the data differences between groups.Result:Tumor growth was significantly lower in treatment groups than that in control group（p<0.05）,and the differences were noted on day 28 post-treatment.The differences of 99mTc-3PRGD2 uptakes were observed between the control group and Endostar group（p=0.033）and the combined treatment group（p<0.01）on day 7 posttreatment and on day 14 posttreatment between the control group and gemcitabine group（p<0.01）.The accumulation of 99mTc-3PRGD2 was significantly correlated with MVD（r=0.998,p=0.002）.Conclusion:With 99mTc-3PRGD2 scintigraphic imaging,the tumor response to antiangiogenic therapy,chemotherapy,and the combined treatment can be observed at an early stage of the treatments,much earlier than the tumor volume change.It provides new opportunities for developing individualized therapies and dose optimization.