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Bamminger K, Pichler V, Vraka C, Limberger T, Moneva B, Pallitsch K, Lieder B, Zacher AS, Ponti S, Benčurová K, Yang J, Högler S, Kodajova P, Kenner L, Hacker M, Wadsak W. Development and In Vivo Evaluation of Small-Molecule Ligands for Positron Emission Tomography of Immune Checkpoint Modulation Targeting Programmed Cell Death 1 Ligand 1. J Med Chem 2024; 67:4036-4062. [PMID: 38442487 PMCID: PMC10945501 DOI: 10.1021/acs.jmedchem.3c02342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 02/15/2024] [Accepted: 02/21/2024] [Indexed: 03/07/2024]
Abstract
A substantial portion of patients do not benefit from programmed cell death protein 1/programmed cell death 1 ligand 1 (PD-1/PD-L1) checkpoint inhibition therapies, necessitating a deeper understanding of predictive biomarkers. Immunohistochemistry (IHC) has played a pivotal role in assessing PD-L1 expression, but small-molecule positron emission tomography (PET) tracers could offer a promising avenue to address IHC-associated limitations, i.e., invasiveness and PD-L1 expression heterogeneity. PET tracers would allow for improved quantification of PD-L1 through noninvasive whole-body imaging, thereby enhancing patient stratification. Here, a large series of PD-L1 targeting small molecules were synthesized, leveraging advantageous substructures to achieve exceptionally low nanomolar affinities. Compound 5c emerged as a promising candidate (IC50 = 10.2 nM) and underwent successful carbon-11 radiolabeling. However, a lack of in vivo tracer uptake in xenografts and notable accumulation in excretory organs was observed, underscoring the challenges encountered in small-molecule PD-L1 PET tracer development. The findings, including structure-activity relationships and in vivo biodistribution data, stand to illuminate the path forward for refining small-molecule PD-L1 PET tracers.
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Affiliation(s)
- Karsten Bamminger
- CBmed
GmbH - Center for Biomarker Research in Medicine, 8010 Graz, Austria
- Department
of Biomedical Imaging and Image-guided Therapy, Division of Nuclear
Medicine, Medical University of Vienna, 1090 Vienna, Austria
| | - Verena Pichler
- CBmed
GmbH - Center for Biomarker Research in Medicine, 8010 Graz, Austria
- Department
of Pharmaceutical Sciences, Division of Pharmaceutical Chemistry, University of Vienna, 1090 Vienna, Austria
| | - Chrysoula Vraka
- Department
of Biomedical Imaging and Image-guided Therapy, Division of Nuclear
Medicine, Medical University of Vienna, 1090 Vienna, Austria
| | - Tanja Limberger
- CBmed
GmbH - Center for Biomarker Research in Medicine, 8010 Graz, Austria
- Institute
of Clinical Pathology, Medical University
of Vienna, 1090 Vienna, Austria
| | - Boryana Moneva
- Department
of Biomedical Imaging and Image-guided Therapy, Division of Nuclear
Medicine, Medical University of Vienna, 1090 Vienna, Austria
| | | | - Barbara Lieder
- Institute
of Physiological Chemistry, University of
Vienna, 1090 Vienna, Austria
- Institute
of Clinical Nutrition, University of Hohenheim, 70599 Stuttgart, Germany
| | - Anna Sophia Zacher
- Department
of Biomedical Imaging and Image-guided Therapy, Division of Nuclear
Medicine, Medical University of Vienna, 1090 Vienna, Austria
| | - Stefanie Ponti
- Department
of Biomedical Imaging and Image-guided Therapy, Division of Nuclear
Medicine, Medical University of Vienna, 1090 Vienna, Austria
| | - Katarína Benčurová
- Department
of Biomedical Imaging and Image-guided Therapy, Division of Nuclear
Medicine, Medical University of Vienna, 1090 Vienna, Austria
| | - Jiaye Yang
- Institute
of Clinical Pathology, Medical University
of Vienna, 1090 Vienna, Austria
| | - Sandra Högler
- Unit
of Laboratory Animal Pathology, University
of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Petra Kodajova
- Unit
of Laboratory Animal Pathology, University
of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Lukas Kenner
- CBmed
GmbH - Center for Biomarker Research in Medicine, 8010 Graz, Austria
- Institute
of Clinical Pathology, Medical University
of Vienna, 1090 Vienna, Austria
- Unit
of Laboratory Animal Pathology, University
of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Marcus Hacker
- Department
of Biomedical Imaging and Image-guided Therapy, Division of Nuclear
Medicine, Medical University of Vienna, 1090 Vienna, Austria
| | - Wolfgang Wadsak
- CBmed
GmbH - Center for Biomarker Research in Medicine, 8010 Graz, Austria
- Department
of Biomedical Imaging and Image-guided Therapy, Division of Nuclear
Medicine, Medical University of Vienna, 1090 Vienna, Austria
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