Preparation of a Promising Angiogenesis PET Imaging Agent: 68Ga-Labeled c(RGDyK)–Isothiocyanatobenzyl-1,4,7-Triazacyclononane-1,4,7-Triacetic Acid and Feasibility Studies in Mice

Journal of Nuclear Medicine

Dong Soo Lee¹  Yun-Sang Lee¹  Myung Chul Lee¹  June-Key Chung¹  Young Joo Kim¹  Gi Jeong Cheon¹  Mee Kyung Hong¹  Young Soo Chang¹  Jae Min Jeong¹ 

关键词: integrin;    NOTA;    gallium;    peptide;    ischemia;    DOTA;   

DOI  :  10.2967/jnumed.107.047423

学科分类：医学（综合）

来源: Society of Nuclear Medicine

【 摘 要 】

Arg-Gly-Asp (RGD) derivatives have been labeled with various radioisotopes for the imaging of angiogenesis in ischemic tissue, in which αvβ3 integrin plays an important role. In this study, cyclic Arg-Gly-Asp-d-Tyr-Lys [c(RGDyK)] was conjugated with 2-(p-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid (SCN-Bz-NOTA) and then labeled with 68Ga. The labeled RGD so produced was subjected to an in vitro binding assay and in vivo biodistribution and PET studies. Methods: A mixture of SCN-Bz-NOTA (660 nmol) and c(RGDyK) (600 nmol) in 0.1 M sodium carbonate buffer (pH 9.5) was allowed to react for 20 h at room temperature in the dark for thiourea bond formation. The conjugate obtained was purified by semipreparative high-performance liquid chromatography (HPLC). The purified c(RGDyK)–SCN-Bz-NOTA (NOTA-RGD) was then labeled with 68Ga from a 68Ge/68Ga generator and purified by semipreparative HPLC. A competitive binding assay for c(RGDyK) and NOTA-RGD was performed with 125I-c(RGDyK) as a radioligand and αvβ3 integrin–coated plates as a solid phase. 68Ga-NOTA-RGD (0.222 MBq/100 μL) was injected, through a tail vein, into mice with hind limb ischemia and into mice bearing human colon cancer SNU-C4 xenografts. Biodistribution and imaging studies were performed at 1 and 2 h after injection. Results: The labeling of NOTA-RGD with 68Ga was straightforward. The Ki values of c(RGDyK) and NOTA-RGD were 1.3 and 1.9 nM, respectively. In the biodistribution study, the mean ± SD uptake of 68Ga-NOTA-RGD by ischemic muscles was 1.6 ± 0.2 percentage injected dose per gram (%ID/g); this uptake was significantly blocked by cold c(RGDyK) to 0.6 ± 0.3 %ID/g (P < 0.01). Tumor uptake was 5.1 ± 1.0 %ID/g, and the tumor-to-blood ratio was 10.3 ± 4.8. Small-animal PET revealed rapid excretion through the urine and high levels of tumor and kidney uptake. Conclusion: Stable 68Ga-NOTA-RGD was obtained in a straightforward manner at a high yield and showed a high affinity for αvβ3 integrin, specific uptake by angiogenic muscles, a high level of uptake by tumors, and rapid renal excretion. 68Ga-NOTA-RGD was found to be a promising radioligand for the imaging of angiogenesis.

【 授权许可】

Unknown