Promising Amino Acid Transporters

There is a great deal of variability
among amino acid transporters1,2

Certain amino acid tracers are taken up by amino acid transporters (LAT1) or alanine-serine-cysteine transporters (ASCT2)1,2

LAT1 and ASCT2 are regularly overexpressed in gliomas, but these targets have their differences2:

ASCT2 is not expressed on the luminal side of the blood-brain barrier. In brain tumors, 18F-fluciclovine uptake is mediated primarily by ASCT2 with reduced fluciclovine uptake observed in >1/3 of non-enhancing tumors, which also had low ASCT2 expression1-4

LAT1 is expressed on both sides of the blood-brain barrier, making it a promising target for amino acid transporters3,5

18F-FET is taken up by LAT1, which is expressed on both sides of the blood-brain barrier. It may offer broad utility in glioma.2,6

Amino acid transport system3

LAT1 is expressed on both sides of the blood-brain barrier

Blood/brain barrier showing blood and brain sides of endothelial cells and where ASCT2 and LAT1 are located on the cells. Blood/brain barrier showing blood and brain sides of endothelial cells and where ASCT2 and LAT1 are located on the cells.

Adapted from Zaragozá R. Front Physiol. 2020;11:973.3 Under a CC BY Creative Commons Attribution License.

Standard of care glioma imaging comes with challenges, but innovation lies on the horizon

The future of
glioma imaging

This agent is not made commercially available or approved for gliomas. It can be made and used investigationally.

ASCT2, alanine-serine-cysteine transporter 2; 18F-FET, 18F-fluoro-ethyl-tyrosine; 18F-FET PET, 18F-fluoro-ethyl-tyrosine positron emission tomography; LAT1, L-type (large neutral) amino acid transporter 1.

References: 1. Scarpelli ML, Healey DR, Mehta S, Quarles CC. Imaging glioblastoma with 18F-fluciclovine amino acid positron emission tomography. Front Oncol. 2022;12:829050. 2. Galldiks N, Lohmann P, Fink GR, Langen K-J. Amino acid PET in neurooncology. J Nucl Med. 2023;64(5):693-700. 3. Zaragozá R. Transport of amino acids across the blood-brain barrier. Front Physiol. 2020;11:973. 4. Axumin. Prescribing information. Blue Earth Diagnostics Ltd; 2022. 5. Li L, Di X, Zhang S, et al. Large amino acid transporter 1 mediated glutamate modified docetaxel-loaded liposomes for glioma targeting. Colloids Surf B Biointerfaces. 2016;141:260-267. 6. Soni N, Ora M, Jena A, et al. Amino acid tracer PET MRI in glioma management: what a neuroradiologist needs to know. AJNR Am J Neuroradiol. 2023;44(3):236-246.