Frontiers in Neuroimaging (Mar 2024)

Characterizing the binding of TC-5619 and encenicline on the alpha7 nicotinic acetylcholine receptor using PET imaging in the pig

  • Janus H. Magnussen,
  • Janus H. Magnussen,
  • Anders Ettrup,
  • Szabolcs Lehel,
  • Dan Peters,
  • Agnete Dyssegaard,
  • Morten S. Thomsen,
  • Morten S. Thomsen,
  • Jens D. Mikkelsen,
  • Jens D. Mikkelsen,
  • Gitte M. Knudsen,
  • Gitte M. Knudsen

DOI
https://doi.org/10.3389/fnimg.2024.1358221
Journal volume & issue
Vol. 3

Abstract

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The alpha7 nicotinic acetylcholine receptor (α7-nAChR) has has long been considered a promising therapeutic target for addressing cognitive impairments associated with a spectrum of neurological and psychiatric disorders, including Alzheimer's disease and schizophrenia. However, despite this potential, clinical trials employing α7-nAChR (partial) agonists such as TC-5619 and encenicline (EVP-6124) have fallen short in demonstrating sufficient efficacy. We here investigate the target engagement of TC-5619 and encenicline in the pig brain by use of the α7-nAChR radioligand 11C-NS14492 to characterize binding both with in vitro autoradiography and in vivo occupancy using positron emission tomography (PET). In vitro autoradiography demonstrates significant concentration-dependent binding of 11C-NS14492, and both TC-5619 and encenicline can block this binding. Of particular significance, our in vivo investigations demonstrate that TC-5619 achieves substantial α7-nAChR occupancy, effectively blocking approximately 40% of α7-nAChR binding, whereas encenicline exhibits more limited α7-nAChR occupancy. This study underscores the importance of preclinical PET imaging and target engagement analysis in informing clinical trial strategies, including dosing decisions.

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