Biological evaluation of 3-[F]fluoro--methyl-D-tyrosine (D-[F]FAMT) as a novel amino acid tracer for positron emission tomography

Ohshima, Yasuhiro; Hanaoka, Hirofumi*; Tominaga, Hideyuki*; Kanai, Yoshikatsu*; Kaira, Kyoichi*; Yamaguchi, Aiko*; Nagamori, Shushi*; Oriuchi, Noboru*; Tsushima, Yoshito*; Endo, Keigo*; Ishioka, Noriko

Since D-amino acid is not distributed much in the non-target organs and is rapidly excreted in the urine, radiotracer using D-amino acid would allow clear PET image of the tumor early after administration. In this study, we prepared 3-[F]fluoro--methyl-D-tyrosine (D-[F]FAMT) and evaluated its usefulness. In biodistribution studies, D-[F]FAMT showed rapid clearance from the blood, marked accumulation and retention in the tumor and low accumulation in non-target organs. The amount of D-[F]FAMT in the tumor was also lowered, tumor-to-blood ratio and tumor-to-muscle ratio of D-[F]FAMT were similar to those of correspondign L-isomer, 3-[F]fluoro--methyl-L-tyrosine (L-[F]FAMT), at every timepoint. Consequently, PET imaging with D-[F]FAMT could not show clear image of the tumor early after the administration. However, D-[F]FAMT enabled higher tumor-to-background contrast than L-[F]FAMT. In conclusions, D-[F]FAMT showed rapid blood clearance, low accumulation in non-target organs, and tumor-selective image compared with L-[F]FAMT. Thus, D-[F]FAMT could potentially serve as a novel PET tracer for imaging malignant tumors.