PET Imaging of VMAT2 with the Novel Radioligand [18F]FE-DTBZ-d4 in Nonhuman Primates: Comparison with [11C]DTBZ and [18F]FE-DTBZ | Zendy

Sangram Nag | Zendy; Mahabuba Jahan | Zendy; Miklós Tóth | Zendy; Ryuji Nakao | Zendy; Andrea Varrone | Zendy; Christer Halldin | Zendy

Open Access

PET Imaging of VMAT2 with the Novel Radioligand [¹⁸F]FE-DTBZ-d4 in Nonhuman Primates: Comparison with [¹¹C]DTBZ and [¹⁸F]FE-DTBZ

Author(s) -

Sangram Nag,

Mahabuba Jahan,

Miklós Tóth,

Ryuji Nakao,

Andrea Varrone,

Christer Halldin

Publication year - 2021

Publication title -

acs chemical neuroscience

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 1.158

H-Index - 69

ISSN - 1948-7193

DOI - 10.1021/acschemneuro.1c00651

Subject(s) - chemistry , vesicular monoamine transporter , radioligand , tetrabenazine , positron emission tomography , vesicular monoamine transporter 2 , biodistribution , monoamine neurotransmitter , dopamine , medicine , nuclear medicine , serotonin , biochemistry , binding site , receptor , in vitro

The vesicular monoamine transporter type 2 (VMAT2) is believed to be responsible for the uptake of monoamines into the vesicles of the synaptic terminals. Two VMAT2 radioligands [ 11 C]DTBZ and [ 18 F]FP-DTBZ have been used to assess the degree of nigrostriatal deficit in Parkinson's disease (PD) using positron emission tomography (PET). [ 18 F]FE-DTBZ-d4, the nondeuterated analogue of [ 18 F]FE-DTBZ showed similar imaging properties with better stability against defluorination. Therefore, [ 18 F]FE-DTBZ-d4 draws attention to be investigated as an imaging marker for VMAT2 in the brain. The aim of this study was to investigate the brain kinetics and quantification of [ 18 F]FE-DTBZ-d4 in nonhuman primates (NHPs), with comparison to [ 11 C]DTBZ and [ 18 F]FE-DTBZ. Radiolabeling was successfully achieved either by one-step 11 C-methylation or by a two-step fluorine-18 nucleophilic substitution reaction. The stability and radiochemical yield were analyzed with high-performance liquid chromatography (HPLC). Three female cynomolgus monkeys were included in the study and underwent a total of 12 positron emission tomography (PET) measurements. Each monkey was examined with each tracer. In addition, two pretreatment and one displacement PET measurements with tetrabenazine (2.0 mg/kg) were performed for [ 18 F]FE-DTBZ-d4. All PET measurements were conducted using a high-resolution research tomograph (HRRT) system. Radiometabolites were measured in monkey plasma using gradient radio-HPLC. [ 18 F]FE-DTBZ-d4 (SUV: 4.28 ± 1.01) displayed higher brain uptake compared to both [ 18 F]FE-DTBZ (SUV: 3.43 ± 0.54) and [ 11 C]DTBZ (SUV: 3.06 ± 0.32) and faster washout. Binding potential (BP ND ) values of [ 18 F]FE-DTBZ-d4 in different brain regions (putamen: 5.5 ± 1.4; caudate: 4.4 ± 1.1; midbrain: 1.4 ± 0.4) were higher than those of [ 11 C]DTBZ and [ 18 F]FE-DTBZ. [ 18 F]FE-DTBZ showed faster radiometabolism in plasma compared to [ 11 C]DTBZ and [ 18 F]FE-DTBZ-d4. [ 18 F]FE-DTBZ-d4 is a suitable radioligand for quantification of VMAT2 in the nonhuman primate brain, with better imaging properties than [ 11 C]DTBZ and [ 18 F]FE-DTBZ. A preliminary comparison suggests that [ 18 F]FE-DTBZ-d4 has increased stability against defluorination compared to the nondeuterated analogue.

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