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BioMed Research International
Volume 2013 (2013), Article ID 460619, 9 pages
http://dx.doi.org/10.1155/2013/460619
Research Article

Synthesis and Biological Evaluation of O-[3-18F-fluoropropyl]-α-methyl Tyrosine in Mesothelioma-Bearing Rodents

Department of Experimental Diagnosis Imaging, Unit 59, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA

Received 12 April 2013; Accepted 6 June 2013

Academic Editor: Tomio Inoue

Copyright © 2013 I-Hong Shih et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Radiolabeled tyrosine analogs enter cancer cells via upregulated amino acid transporter system and have been shown to be superior to 18F-fluoro-2-deoxy-D-glucose (18F-FDG) in differential diagnosis in cancers. In this study, we synthesized O-[3-19F-fluoropropyl]-α-methyl tyrosine (19F-FPAMT) and used manual and automated methods to synthesize O-[3-18F-fluoropropyl]-α-methyl tyrosine (18F-FPAMT) in three steps: nucleophilic substitution, deprotection of butoxycarbonyl, and deesterification. Manual and automated synthesis methods produced 18F-FPAMT with a radiochemical purity >96%. The decay-corrected yield of 18F-FPAMT by manual synthesis was 34% at end-of-synthesis (88 min). The decay-corrected yield of 18F-FPAMT by automated synthesis was 15% at end-of-synthesis (110 min). 18F-FDG and 18F-FPAMT were used for in vitro and in vivo studies to evaluate the feasibility of 18F-FPAMT for imaging rat mesothelioma (IL-45). In vitro studies comparing 18F-FPAMT with 18F-FDG revealed that 18F-FDG had higher uptake than that of 18F-FPAMT, and the uptake ratio of 18F-FPAMT reached the plateau after being incubated for 60 min. Biodistribution studies revealed that the accumulation of 18F-FPAMT in the heart, lungs, thyroid, spleen, and brain was significantly lower than that of 18F-FDG. There was poor bone uptake in 18F-FPAMT for up to 3 hrs suggesting its in vivo stability. The imaging studies showed good visualization of tumors with 18F-FPAMT. Together, these results suggest that 18F-FPAMT can be successfully synthesized and has great potential in mesothelioma imaging.