Dieter Ory1, Sofie Celen2, Rik Gijsbers3, Chris Van Den Haute4, Andrey Postnov5, Michel Koole5, Caroline Vandeputte5, José-Ignacio Andrés6, Jesus Alcazar6, Meri De Angelis6, Xavier Langlois6, Anindya Bhattacharya7, Mark Schmidt8, Michael A Letavic9, Wim Vanduffel10, Koen Van Laere5, Alfons Verbruggen2, Zeger Debyser11, Guy Bormans12. 1. Laboratory for Radiopharmacy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium Laboratory for Molecular Virology and Gene Therapy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium. 2. Laboratory for Radiopharmacy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium. 3. Laboratory for Molecular Virology and Gene Therapy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium Leuven Viral Vector Core, KU Leuven, Leuven, Belgium. 4. Leuven Viral Vector Core, KU Leuven, Leuven, Belgium Laboratory for Neurobiology and Gene Therapy, Department of Neurosciences, KU Leuven, Leuven, Belgium. 5. Nuclear Medicine and Molecular Imaging, Department of Imaging and Pathology, University Hospital and KU Leuven, Leuven, Belgium. 6. Janssen Research and Development, Discovery Sciences, a Division of Janssen-Cilag, Toledo, Spain. 7. Janssen Research and Development, Discovery Sciences, a Division of Janssen-Cilag, Toledo, Spain Janssen Research and Development, LLC, San Diego, California. 8. Janssen Research and Development, Neuroscience Discovery, a Division of Janssen Pharmaceutica Nevada, Beerse, Belgium; and. 9. Janssen Research and Development, LLC, San Diego, California. 10. Laboratory for Neuro- and Psychophysiology, Department of Neurosciences, KU Leuven, Leuven, Belgium. 11. Laboratory for Molecular Virology and Gene Therapy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium. 12. Laboratory for Radiopharmacy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium Guy.Bormans@pharm.kuleuven.be.
Abstract
UNLABELLED: The P2X7 receptor (P2X7R) orchestrates neuroinflammation, and this is the basis for an increased interest in the development of antagonists inhibiting P2X7R function in the brain. This study provides the preclinical evaluation of (11)C-JNJ-54173717, a PET tracer for P2X7R in both rats and nonhuman primates. METHODS: (11)C-JNJ-54173717 is a high-affinity radiotracer for the human P2X7R (hP2X7R). Biodistribution and radiometabolite studies were performed. Viral vectors encoding either enhanced green fluorescent protein-hP2X7R or 3flag-hP2X7R were engineered and validated in cell culture. hP2X7R was regionally overexpressed in the rat striatum after stereotactic injection of viral vectors. Dynamic small-animal PET studies were performed in vector-injected rats and in healthy monkeys using (11)C-JNJ-54173717. RESULTS: The affinity of JNJ-54173717 was 1.6 ± 0.1 nM in a rat cortex P2X7R membrane binding assay. In a functional assay at the recombinant human and rat P2X7R orthologs, the half maximal inhibitory concentration (IC50) of JNJ-54173717 was 4.2 ± 0.01 nM and 7.6 ± 0.01 nM, respectively. The rat biodistribution study showed that (11)C-JNJ-54173717 crossed the blood-brain barrier and was cleared from plasma mainly via the hepatobiliary pathway. A polar radiometabolite was found in rat plasma. No radiometabolites were detected in rat brain. Dynamic small-animal PET showed binding of (11)C-JNJ-54173717 in the striatum expressing hP2X7R, with rapid washout from the noninjected control striatum and other brain regions. Likewise, (11)C-JNJ-54173717 PET signal was blocked by a chemically distinct P2X7R ligand, indicating specific binding to P2X7R in the monkey brain. CONCLUSION: JNJ-54173717 is a high-affinity P2X7R antagonist. An animal rat model stably expressing hP2X7R was developed and validated, identifying favorable characteristics for (11)C-JNJ-54173717 as a PET radioligand for in vivo visualization of hP2X7R. (11)C-JNJ-54173717 selectively visualized P2X7R in the monkey brain, and this radioligand will be further evaluated in a clinical setting to study P2X7R expression levels in neurodegenerative disorders.
UNLABELLED: The P2X7 receptor (P2X7R) orchestrates neuroinflammation, and this is the basis for an increased interest in the development of antagonists inhibiting P2X7R function in the brain. This study provides the preclinical evaluation of (11)C-JNJ-54173717, a PET tracer for P2X7R in both rats and nonhuman primates. METHODS: (11)C-JNJ-54173717 is a high-affinity radiotracer for the human P2X7R (hP2X7R). Biodistribution and radiometabolite studies were performed. Viral vectors encoding either enhanced green fluorescent protein-hP2X7R or 3flag-hP2X7R were engineered and validated in cell culture. hP2X7R was regionally overexpressed in the rat striatum after stereotactic injection of viral vectors. Dynamic small-animal PET studies were performed in vector-injected rats and in healthy monkeys using (11)C-JNJ-54173717. RESULTS: The affinity of JNJ-54173717 was 1.6 ± 0.1 nM in a rat cortex P2X7R membrane binding assay. In a functional assay at the recombinant human and rat P2X7R orthologs, the half maximal inhibitory concentration (IC50) of JNJ-54173717 was 4.2 ± 0.01 nM and 7.6 ± 0.01 nM, respectively. The rat biodistribution study showed that (11)C-JNJ-54173717 crossed the blood-brain barrier and was cleared from plasma mainly via the hepatobiliary pathway. A polar radiometabolite was found in rat plasma. No radiometabolites were detected in rat brain. Dynamic small-animal PET showed binding of (11)C-JNJ-54173717 in the striatum expressing hP2X7R, with rapid washout from the noninjected control striatum and other brain regions. Likewise, (11)C-JNJ-54173717 PET signal was blocked by a chemically distinct P2X7R ligand, indicating specific binding to P2X7R in the monkey brain. CONCLUSION: JNJ-54173717 is a high-affinity P2X7R antagonist. An animal rat model stably expressing hP2X7R was developed and validated, identifying favorable characteristics for (11)C-JNJ-54173717 as a PET radioligand for in vivo visualization of hP2X7R. (11)C-JNJ-54173717 selectively visualized P2X7R in the monkey brain, and this radioligand will be further evaluated in a clinical setting to study P2X7R expression levels in neurodegenerative disorders.
Authors: Stefanie M A Willekens; Donatienne Van Weehaeghe; Philip Van Damme; Koen Van Laere Journal: Eur J Nucl Med Mol Imaging Date: 2016-12-08 Impact factor: 9.236
Authors: Anindya Bhattacharya; Brian Lord; Jan-Sebastian Grigoleit; Yingbo He; Ian Fraser; Shannon N Campbell; Natalie Taylor; Leah Aluisio; Jason C O'Connor; Mariusz Papp; Christa Chrovian; Nicholas Carruthers; Timothy W Lovenberg; Michael A Letavic Journal: Neuropsychopharmacology Date: 2018-07-09 Impact factor: 7.853
Authors: Donatienne Van Weehaeghe; Michel Koole; Mark E Schmidt; Stephanie Deman; Andreas H Jacobs; Erika Souche; Kim Serdons; Stefan Sunaert; Guy Bormans; Wim Vandenberghe; Koen Van Laere Journal: Eur J Nucl Med Mol Imaging Date: 2019-06-26 Impact factor: 9.236