부산대학교 도서관

Radiopharmaceuticals using a radioisotope play a major role in the diagnosis and therapy of tumors by non-invasive methods. It is composed of the binding of radioactive isotopes to biologically active molecules which are associated with biomechanisms. Exceptionally, radioactive isotopes, such as 131I and 201Tl could show themselves biomechanisms. Radiopharmaceuticals are important to consider the design criteria in accordance with the intended use before starting to develop of novel radiopharmaceuticals. In the study of these radiopharmaceuticals, the discovery and modification of biologically active molecules are very important. In this paper, we have studied using biologically active molecules of various sizes and functions.64Cu-ATSM was developed for the effective diagnosis and for enhancement of radiation therapy effect of hypoxia lesion in tumor. Radiochemical purity of final product (64Cu-ATSM) was over 98%. The stability in human serum showed a very high stability for 17 h. However, stability in mouse serum was decomposited over 98% post 3 h. In imaging study, 18F-FDG uptake of 71-year-old woman with advanced cervical cancer was very high. However, the distribution was not uniform. The uptake of 64Cu-ASTM in tumor showed a pattern similar with the 18F-FDG.Gluco-Cyclic RGD Dimers and PEGylated dimeric c(RGD-ACH-K) were developed for an effective tumor imaging by the high uptake of 3-integrin receptor in neovascular endothelial cells. In this study, we performed a comparison of 64Cu-labeled dimer RGD conjugates using 3 different chelators, DOTA, NOTA and NODAGA as Bifunctional chelating agent (BFCA). The radiochemical purity of the final products (R8 (DOTA), R9 (NOTA) and R10 (NODAGA)) were greater than 99%. Furthermore, stability in human and mouse serum showed a very high stability for 24 h. The calculated IC50 values, which represented the 50% inhibitory concentration of 125I-echistatin binding, were 14.6 nM (8), 14.2 nM (9), 15.3 nM (10) and 27.3 nM (c(RGDyK)). The dimeric cyclic RGD peptides showed better uptake with a longer tumor retention time than their monomeric cyclic RGD analogs. The log P values for R8, R9 and R10 were -3.57 ± 0.08, -3.75 ± 0.04 and -3.21 ± 0.1, respectively. Therefore, the NOTA conjugated peptide (R9) was slightly more hydrophilic than the cyclic RGD peptides conjugated to DOTA (R8) and NODAGA (R10). In biodistribution, the tumor uptake of R8-10 followed the order R9 > R8 > R10. In PET/CT study, one characteristic feature of R10 was gallbladder enhancement. This finding suggests that the higher gallbladder uptake of R10 was most likely caused by the presence of glucosamine-based sugar amino acid motifs in R10. As a result, the hepatobiliary uptake followed by excretion through the intestine would be a predominant pattern for R10 compared with the control. In addition, tumor uptake of R9 was highest for R8-10 at 4 h p.i., and the liver uptake of R9 was the lowest, which is consistent with the results of the biodistribution study.Next, the synthesis of a PEGylated dimeric c(RGD-ACH-K) peptides and evaluate a comparison of two chelators DOTA and NOTA for in vivo PET imaging. The radiochemical purities of 64Cu-DOTA-PEG-[c(RGD-ACH-K)]2 and 64Cu-NOTA-PEG-[c(RGD-ACH-K)]2 were over 99%. Both PEGylated dimeric RGD conjugates showed good stability in serum and PBS for up to 48 h. The liver uptake of complexes 64Cu-DOTA-PEG-[c(RGD-ACH-K)]2 or 64Cu-NOTA-PEG-[c(RGD-ACH-K)]2 was significantly lower compared to that of 64Cu-DOTA-c(RGD-ACH-K). However, tumor uptake of complexes 64Cu-DOTA-PEG-[c(RGD-ACH-K)]2 was slightly lower compared to that of 64Cu-DOTA-c(RGD-ACH-K). Because of its fast blood clearance, tumor accumulation of 64Cu-DOTA-PEG-[c(RGD-ACH-K)]2 was lower than that of 64Cu-DOTA-c(RGD-ACH-K). In contrast, the tumor/blood ratio of 64Cu-DOTA-PEG-[c(RGD-ACH-K)]2 was higher than that of 64Cu-DOTA-c(RGD-ACH-K). In this studies, we designed and synthesized two PEGlyated dimeric RGD peptides, 64Cu-DOTA-PEG-[c(RGD-ACH-K)]2 and 64Cu-NOTA-PEG-[c(RGD-ACH-K)]2, for use as PET radiopharmaceuticals.64Cu-labeled aptamers were developed for the diagnosis of lymphoma using aptamer analogues, modifying 5’-hydroxy group of adenosine in aptamer for visualization of lymphoma by PET scanning. In this studies, all aptamer analogues were prepared as our order from Integrated DNA Technolgies (U.S.A) and chelator used a p-SCN-Bn-DOTA. The radiochemical purities of 64Cu-labeled conjugates after purification was greater than 97 ± 2 %. All aptamer conjugates showed good stability in human and mouse serum. In cellular uptake studies, we had expected to increase the cellular uptake in proportion to the length of the alkyl chain. As expected, 64Cu-DOTA-C12-sgc8c was the highest among sgc8c analogues. However, 64Cu-DOTA-C6-td05 was the highest among td05 analogues, unexpectedly. We, thus, chose 64Cu-DOTA-C6-td05 and 64Cu-DOTA-C12-sgc8c as final PET imaging agents for lymphoma. Small animal PET/CT images were obtained in SCID mice bearing CEM and Ramos tumors (n = 4) at 24 h using a microPET scanner. Animal PET/CT images remarkably were detected the tumor on each left shoulder at 24 h. However, the most of the radioactivity was accumulated in the liver by slow clearance of both tracers. 89Zr-labeled trastuzumab and thio-trastuzumab were developed as immunoPET agent for noninvasive in vivo imaging in HER2 overexpression tumors. In our studies, the trastuzumab was prepared by coupling Df-Bz-NCS to the lysine groups of trastuzumab mAb. Also, the thio-trastuzumab was prepared by coupling Df-Chx-Mal to the cysteine groups of thio-trastuzumab mAb. The radiochemical purities of 89Zr-Df-trastuzumab and 89Zr-Df-thio-trastuzumab were over 95%. However, Final radiochemical purity after Amicon Ultra purification was over 98% in all 89Zr-labeled analogues. The stability of 89Zr-Df-Bz-trastuzumab and 89Zr-Df-Chx-Mal-thio-trastuzumab was determined in PBS and mouse serum and was showed a very high stability (>95%) for up to 7 days. The cell uptake of Df-trastuzumab and Df-thio-trastuzumab increased slowly for up to 48 h. However, these results showed that Df-Bz-trastuzumab is approximately 2 times higher than Df-Chx-Mal-thio-trastuzumab. ImmunoPET/CT imaging was evaluated in xenografts of NCI-N87 (HER2 positive). Each mouse was scanned at various time points (24, 48, 72, and 96 h) after injection of 100±1.0μCi of radiopharmaceuticals. Representative PET images showed remarkable tumors on the left shoulder of each mouse. Both 89Zr-Df-Bz-trastuzumab and 89Zr-Df-Chx-Mal-thio-trastuzumab were showed the most clear tumor uptake at 48 h as in the cellular uptake studies. We prepared 89Zr-labeled conjugates of two, 89Zr-Df-trastuzumab and 89Zr-Df-thio-trastuzumab, as high efficiency from the production of 89Zr to radiolabeling method. The trastuzumab was evaluated far superior than thio-trastuzumab in economic or diagnosis aspect.This research was performed to develop five new radiopharmaceuticals, and conducted the in vitro/in vivo studies to evaluate theragnostic efficacy of each radiopharmaceuticals. The preliminary research on a new radiotracer, which has the potential as 89Zr-antibody (Ab), in this study, is expected to induce the advanced theragnostic technology through a more detailed and systematic follow-up study.