Synthesis And Application Of Tumor Vascular Targeting Molecular Probes ¹⁸F-AlF-p-SCN-NOTA-IF7 And ¹⁸F-AlF-p-SCN-NODA-IF7

PurposePrepare tumor imaging agents ¹⁸F-AlF-p-SCN-NOTA-IF7 and ¹⁸F-AlF-p-SCN-NODA-IF7 against tumor vascular surface receptor Annexin A1（Anxa1）.Investigate the vitro tumor cells（human epidermal carcinoma A431 Cells）studies.Evaluate the vitro biological distribution and Micro-PET imaging efficacy in Balb/c mice bearing A431tumors.Methods1、IFLLWQR（IF7）was mixed with S-2-（4-isothio）-1,4,7-triazacyclononane-1,4,7-triacetic acid（p-SCN-NOTA）or S-2-（4-isothio）-1,4,7-triazacyclononane-1,4-dicarboxylic acid（p-SCN-NODA）（mole ratio 1:1.2）and dissolved in 1 m L DMF.After incubated at 37℃water bath overnight,the mixture was purified by semipreparative HPLC with a linear gradient.2、A 1 m L vial was charged with p-SCN-NOTA-IF7 or p-SCN-NODA-IF7（100μg）in 10μL H₂O.Then,6μL of a solution of aluminum chloride（2 mmol/L）in 0.2 mol/L p H4 sodium acetate buffer and 10μL carboxylic acid were added,followed by cyclotron target water containing ¹⁸F-fluoride（1.11 GBq）.Finally four times the volume of acetonitrile was added.The resulting solution was heated at 100°C oil bath for 10 min.The stability of ¹⁸F-AlF-p-SCN-NOTA-IF7 or ¹⁸F-AlF-p-SCN-NODA-IF7 was tested in human serum.3、The radioactiviy counts were measured afer A 431 cells incubated with ¹⁸F-AlF-p-SCN-NOTA-IF7 or ¹⁸F-AlF-p-SCN-NODA-IF7.The uptake rates were calculated.4、Micro-PET imaging and biodistribution studies were conducted on BALB/c mice bearing A431 tumors.Results1、¹⁸F-AlF-p-SCN-NOTA-IF7 or ¹⁸F-AlF-p-SCN-NODA-IF7 can be efficiently produced within 30 min with decay corrected yield of 92%and 94%,repectively.The radiochemical purity of ¹⁸F-AlF-p-SCN-NOTA-IF7 or ¹⁸F-AlF-p-SCN-NODA-IF7 was greater than 95%.The imaging agents were stable in human serum for at least 2 h with radiochemical purity greater than 90%.2、The vitro A431 cells uptake of ¹⁸F-AlF-p-SCN-NOTA-IF7 and ¹⁸F-AlF-p-SCN-NODA-IF7 can reach highest at 60 min（2.67±0.85%AD and 2.45±0.65%AD,respectively）.Excessive IF7 can significantly reduce the uptake rates.3、A431 tumor in the animal model was clearly visible with good contrast to background.High uptake of tumor by quantification of the PET data was determined to be1.66±0.43%ID/g,0.76±0.56%ID/g at 30 min,60 min p.i.,respectively for ¹⁸F-AlF-p-SCN-NOTA-IF7.High uptakes of tumor were 1.45±0.21%ID/g and 0.69±0.47%ID/g at30 min,60 min p.i.,respectively for ¹⁸F-AlF-p-SCN-NODA-IF7.Anxal binding specificity was demonstrated by coinjection an excess of unlabeled IF7 with ¹⁸F-AlF-p-SCN-NODA-IF7 and A431 tumor uptake was found to be reduced.4、In vivo bio-distribution results are consistent with Micro-PET imaging results,which showing that drugs are cleared fast in the plasma.The high gastrointestinal uptake showed that both ¹⁸F-AlF-p-SCN-NOTA-IF7 and ¹⁸F-AlF-p-SCN-NODA-IF7 were excreted mainly through gastrointestinal.The ratios of tumor to muscle,tumor to blood were 3.71±0.48 and 1.01±0.22,4.44±0.63 and 0.93±0.30,2.85±1.59 and 1.10±0.23,respectively,after injection of ¹⁸F-AlF-p-SCN-NOTA-IF7 for 30 min,60 min and 120 min.The uptake ratios of tumor to muscle,tumor to blood were 3.56±0.37 and 1.12±0.24,3.02±0.28 and 0.90±0.28,3.13±1.34 and 1.35±0.25,respectively,after injection of¹⁸F-AlF-p-SCN-NODA-IF7 for 30,60 and 120 min.Conclusion¹⁸F-AlF-p-SCN-NOTA-IF7 or ¹⁸F-AlF-p-SCN-NODA-IF7 could be prepared in a simple procedure with high radiochemical purity.Micro-PET imaging showed the tumor was significantly obseved ¹⁸F-AlF-p-SCN-NOTA-IF7 and ¹⁸F-AlF-p-SCN-NODA-IF7with ideal biodistribution and good targetability.Therefore,they are promise tracers for tumor imaging.