A Novel Method of 18F Radiolabeling for PET

Journal of Nuclear Medicine

Chien-Hsing Chang¹  William J. McBride¹  Peter Laverman¹  David M. Goldenberg¹  Christopher A. D'Souza¹  Edmund A. Rossi¹  Habibe Karacay¹  Otto C. Boerman¹  Robert M. Sharkey¹ 

关键词: bispecific antibody;    cancer;    CEACAM5;    ¹⁸F;    pretargeting;    molecular imaging;    PET;   

DOI  :  10.2967/jnumed.108.060418

学科分类：医学（综合）

来源: Society of Nuclear Medicine

【 摘 要 】

Small biomolecules are typically radiolabeled with 18F by binding it to a carbon atom, a process that usually is designed uniquely for each new molecule and requires several steps and hours to produce. We report a facile method wherein 18F is first attached to aluminum as Al18F, which is then bound to a chelate attached to a peptide, forming a stable Al18F-chelate-peptide complex in an efficient 1-pot process. Methods: For proof of principle, this method was applied to a peptide suitable for use in a bispecific antibody pretargeting method. A solution of AlCl3·6H2O in a pH 4.0 sodium-acetate buffer was mixed with an aqueous solution of 18F to form the Al18F complex. This was added to a solution of IMP 449 (NOTA-p-Bn-CS-d-Ala-d-Lys(HSG)-d-Tyr-d-Lys(HSG)-NH2) (NOTA-p-Bn-CS is made from S-2-(4-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid; HSG is histamine-succinyl-glycine) and heated to 100°C for 15 min. In vitro and in vivo stability and targeting ability of the Al18F-IMP 449 were examined in nude mice bearing LS174T human colonic tumors pretargeted with an anti-CEACAM5 bispecific antibody (TF2). Results: The radiolabeled peptide was produced in 5%−20% yield with an estimated specific activity of 18,500–48,100 GBq (500–1,300 Ci)/mmol. The Al18F-IMP 449 was stable for 4 h in serum in vitro, and in animals, activity isolated in the urine 30 min after injection was bound to the peptide. Nonchelated Al18F had higher tissue uptake, particularly in the bones, than the chelated Al18F-IMP 449, which cleared rapidly from the body by urinary excretion. Tumor uptake was 30-fold higher with TF2-pretargeted Al18F-IMP 449 than with the peptide alone. Dynamic PET showed tumor localization within 30 min and rapid and thorough clearance from the body. Conclusion: The ability to bind highly stable Al18F to metal-binding ligands is a promising new labeling method that should be applicable to a diverse array of molecules for PET.

【 授权许可】

Unknown