Preparation and preliminary biological evaluation of n-Gluc-Lys([Al¹⁸ F]NOTA)-TOCA

Octreotide and their derivatives can specificially bind with somatostatin receptor (SSTR) which is usually over-expressed on many tumor cells. So ¹⁸F labeled octreotide and their derivatives can be used for the diagnosis and evaluation of therapeutic efficacy of SSTR positive tumors. In order to explore a novel PET probe for diagnosis of SSTR positive tumors, the n-Gluc-Lys([Al¹⁸F]NOTA)-TOCA was radio-synthesized fast and efficiently using the chelation reaction of n-Gluc-Lys(NOTA)-TOCA with Al¹⁸F moiety, n-Gluc-Lys([Al¹⁸F]NOTA)-TOCA was a glycosylated octreotide derivative combined with 1, 4, 7-triazacyclononane-1, 4, 7-triacetic acid(NOTA). The labeling efficiency of n-Gluc-Lys([Al¹⁸F]NOTA)-TOCA is 69% and the total synthesis time is 25-30 min. The radiochemical purity is over 95% after HLB column purification. The stability in vitro is excellent, and the hydrophilicity is high (lg P = -4.20 ± 0.09(n = 3)). Biodistribution studies in normal mice at 2 h after injection show that the uptake of n-Gluc-Lys([Al¹⁸F]NOTA)-TOCA in kidney is high ((13.83 ± 3.52)% ID/g(n = 5)) and the uptake in liver and bone is low. The uptake in samatostatin pancreas receptor express is high, and the background of blood and muscle is low. These preliminary results provide some experimental basis for further study of Al¹⁸F complex labeled octreotide and their analogues as tumor probes for the diagnosis of SSTR-positire tumors. (authors)