TY - JOUR T1 - Radio synthesis and basic evaluation of [18F] NKO 028 as a L-type amino acid transporter 1 (LAT1) PET tracer for cancer diagnosis. JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 1185 LP - 1185 VL - 57 IS - supplement 2 AU - Yasukazu Kanai AU - Tadashi Watabe AU - Shushi Nagamori AU - Sadahiro Naka AU - Toshihiro Sakai AU - Hiroki Kato AU - Kayako Isohashi AU - Mitsuaki Tatsumi AU - Eku Shimosegawa AU - Yoshikatsu Kanai AU - Jun Hatazawa Y1 - 2016/05/01 UR - http://jnm.snmjournals.org/content/57/supplement_2/1185.abstract N2 - 1185Objectives L-type amino acid transporter 1 (LAT1) is expressed specifically in tumor cells. Therefore LAT1 is a target of anti-tumor drug development. NKO 028, LAT1 selective substrate, was developed as an anti-cancer agent in Osaka University. NKO 028 is derivative of aromatic amino acid. NKO 028 has high affinity for LAT1. NKO 028 is good candidate for cancer diagnosis. We tried to establish radiolabeling method of NKO 028 with fluorine-18 and investigated basic character of [18F] NKO 028 in small animals.Methods In radiolabeling of [18F] NKO 028, we investigate concentration of precursor, reaction temperature, reaction time in fluorination step, appropriate base (potassium carbonate, tetrabutyl ammonium hydroxide, cesium carbonate or cesium hydrogen carbonate) and hydrolysis condition. [18F] NKO 028 (0.2 MBq) was administrated to normal mice. Mice were sacrificed in 5, 15, 30 and 60 minutes after injection. Major organs and tissues were taken. Radioactivity was measured with well counter.Results More than 5 mg/ml of precursor concentration, 80 deg C of reaction temperature and 5 minutes of reaction time gave high radiochemical yield in [18F] NKO 028 radiolabeling. Acetonitrile was best for reaction solvent, because solubility for NKO 028 precursor is very high. Under the optimized condition, F-18 fluorination efficiency was more than 70 %.Potassium carbonate gave 50 % of [18F] NKO 028 racemate form. Tetrabutyl ammonium hydroxide resulted in low radiochemical yield because of low solubility for acetonitrile. In hydrolysis step, 1.0 mol/L hydro chloric acid resulted in 30 % of radiochemical yield. Under the optimized condition, we synthesized [18F] NKO 028 with 30 % of radiochemical yield within 80 minutes from end of bombardment. High accumulations of [18F] NKO 028 was found in spleen at 5 minutes after injection (1.4 % ID/g) and kidney at 15 minutes after injection (1.0 % ID/g), respectively. But accumulation in spleen, kidney and other major organs and tissues were decrease rapidly. No specific accumulations were observed in major organs or tissues in normal mice.Conclusions We succeeded to synthesize [18F] NKO 028 with 30 % of radiochemical yield. We confirm that [18F] NKO 028 did not accumulate in normal organs and tissues. Accumulation of [18F] NKO 028 is now testing in tumor bearing mice. ER -