• Biomedical Science Letters
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• v.3 no.2
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• pp.125-130
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• 1997

Taxol, an anticancer drug that has diterpenoid conformation, has been used as an effective chemotherapeutical agent in the treatment of breast and ovarian cancers. Because of its toxicity like other anticancer drugs, monitoring the taxol level in serum is important procedure during cancer therapy. The various monitoring methods using HPLC, ELISA, and RIA have been adopted, and RIA technique is known to be superior than other methods in trems of sensitivity and convenience. In this study, in order to develope taxol RIA system using $^{125}$I labelled antigen, first of all we synthesized taxol derivatives. 2'-hemisuccinyltaxol was obtained with about 80％ yield by esterification of taxol at C-2' hydroxyl group on C-13 carbon with succinic anhydride. [$^{125}$I]iodotyramine was prepared with 58％ labelling yield by radioiodination of tyramine and purified by gel chromatography. 2'-[$^{125}$I]iodotyramine-hemisuninyltaxol, $^{125}$I labelled antigen for taxol RIA, was synthesized with 96% yield from conjugation of 2'-hemisuccinyltaxol and [$^{125}$I]iodotyramine. Anti-taxol serum was produced from the rabbit immunized with 2'-hemisuccinyltaxol-BSA synthesized by 2'-hemisuccinyltaxol and BSA. The antiserum titer was determined by RIA using 2'-[$^{125}$I]iodotyramine-hemisuccinyltaxol. The titer of 1:20 was obtained with about 40% of B/T. The results suggest that taxol RIA using $^{125}$I labelled antigen can be applied to monitor the taxol level in serum.

• The Korean Journal of Nuclear Medicine
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• v.31 no.4
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• pp.440-451
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• 1997

This study was designed to prospect the $^{111}In$-labelled paclitaxel as tumor imaging agent. In order to provide a taxol molecule with a functional group which is able to chelate In-111, taxol-DTPA conjugate and 2'-hemisuccinyltaxol were synthesized by esterification of taxol at C-2'on C-13 carbon with DTPA anhydride and succinic anhydride, respectively. Synthesis yield of the taxol derivatives was 34% for taxol-DTPA and 80% for 2'-hemisuccinyltaxol. Cytotoxicity of the taxol derivatives were measured by MTT method toward cell lines HT29, B16, P388, and CT26. The cytotoxic activities of the taxol derivatives were maintained, although less active than taxol. Radiolabelling of the taxol derivatives were proceeded directly with $^{111}InCl_3$ or indirectly with $^{111}In$-citrate(ligand-exchange method). The ligand-exchange method was not suitable because some precipitates appeared during the reaction. On the contrary, by direct radiolabelling method, we were able to obtain taxol-DTPA-$^{111}In$ in 100% radiochemical yield. However, 2'-hemisuccinyltaxol was not labelled by both methods. Yield and radiochemical purity of the radiolabelled com-pound were determined by HPLC, paper chromatography and instant thin layer chromatography. Taxol-DTPA-$^{111}In$ was characterized to be hydrophilic by lipophilicity test, and nearly non-adhesive to HT29, B16, P388, and CT26 by cell binding affinity test. Binding affinity of the taxol-DTPA-$^{111}In$ complex to serum proteins was also examined by protein precipitation with 30% trichloroacetic acid. The results showed that 30% of the taxol-DTPA-$^{111}In$ complex binds with serum proteins.

• The Korean Journal of Nuclear Medicine
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• v.36 no.2
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• pp.121-132
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• 2002

Purpose : Taxol(Paclitaxel), an antineoplastic agent, has been used in the treatment of ovarian and breast cancers. The determination of optimal Taxol concentrations in human serum was required for enhancing therapeutic effect and maintaining the appropriate Taxol level in blood. This study was aimed to synthesizeradiolabeled Taxol derivatives as radiotracer in competitive radioimmunoassay for monitoring Taxol concentrations in blood and to determine the usefulness of its derivatives. Materials and Methods : Hemisucdcinyltaxol(HT) was synthesized by esterification of Taxol with succinic anhydride. Tyraminehemisuccinyltaxol(THT) was synthesized by coupling of HT with tyramine using isobutylchlormate as coupling agent and purified by HPLC. By using chloramine-T($5.25mg/ml,\;10{\mu}{\ell}$) as oxidant agent, THT($4mg/ml,\;30{\mu}{\ell}$) was labeled wity $^{125}I\;(37MBq,\;1mCi)$. To estimate the stability of purified THT, $^{125}I-iodotyraminehemisuccinyltaxol(^125}ITHT)$ was dissolved in 80% acetonitrile aqueous solution, and the solution was incubated at $4^{\circ}C\;and\;37^{\circ}C$ for 7 days. At various time intervals, the stability of THT and $^{125}ITHT$ was monitored. The titer of Taxol monoclonal antibody, 3G5A7, was determined by competitive radioimmunoassay using $^{125}ITHT$ as a labeled antigen. A standard dose-response curve was demonstated by Taxol competitive radioimmunoassay. Resulls : HT and THT were synthesized with 79.9% and 19.5% yield, respectively. The labeling yield of $^{125}ITHT$ was 93%. After 7 days, the chemical purity of THT was 96.5% at $4^{\circ}C$, and 97.5% at $37^{\circ}C$. After 3 days, $^{125}ITHT$ was stable with 94.7% at $4^{\circ}C$ and 93.4% at $37^{\circ}C$. After 7 days, fadiochemical purity was diminished to 88.1% at $37^{\circ}C$. The titer of Taxol monoclonal antibody, 3G5A7, was determined to 1:256. A standard dose-response curve demonstated good collinearity ($R^2=0.971$) as Taxol concentration-dependent manner. Conclusion : Competitive radioimmunoassay using $^{125}I-iodotyraminehemisuccinytaxol$ as radiotracer could be used to monitor for concentration of Taxol in the human serum.