Discovery of a Promising Fluorine-18 Positron Emission Tomography Radiotracer for Imaging Sphingosine-1-Phosphate Receptor 1 in the Brain

J Med Chem. 2023 Apr 13;66(7):4671-4688. doi: 10.1021/acs.jmedchem.2c01752. Epub 2023 Mar 16.

Abstract

Sphingosine-1-phosphate receptor 1 (S1PR1) is recognized as a novel therapeutic and diagnostic target in neurological disorders. We recently transferred the S1PR1 radioligand [11C]CS1P1 into clinical investigation for multiple sclerosis. Herein, we reported the design, synthesis and evaluation of novel F-18 S1PR1 radioligands. We combined the structural advantages of our two lead S1PR1 radioligands and synthesized 14 new S1PR1 compounds, then performed F-18 radiochemistry on the most promising compounds. Compound 6h is potent (IC50 = 8.7 nM) and selective for S1PR1. [18F]6h exhibited a high uptake in macaque brain (SUV > 3.0) and favorable brain washout pharmacokinetics in positron emission tomography (PET) study. PET blocking and displacement studies confirmed the specificity of [18F]6h in vivo. Radiometabolite analysis confirmed no radiometabolite of [18F]6h entered into the brain to confound the PET measurement. In summary, [18F]6h is a promising radioligand to image S1PR1 and worth translational clinical investigation for humans with brain disorders.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Brain* / diagnostic imaging
  • Fluorine Radioisotopes* / pharmacokinetics
  • Macaca
  • Positron-Emission Tomography* / methods
  • Radiopharmaceuticals* / chemistry
  • Sphingosine-1-Phosphate Receptors

Substances

  • Fluorine Radioisotopes
  • Fluorine-18
  • Radiopharmaceuticals
  • Sphingosine-1-Phosphate Receptors