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Badenhorst M, Windhorst AD, Beaino W. Navigating the landscape of PD-1/PD-L1 imaging tracers: from challenges to opportunities. Front Med (Lausanne) 2024; 11:1401515. [PMID: 38915766 PMCID: PMC11195831 DOI: 10.3389/fmed.2024.1401515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Accepted: 05/20/2024] [Indexed: 06/26/2024] Open
Abstract
Immunotherapy targeted to immune checkpoint inhibitors, such as the program cell death receptor (PD-1) and its ligand (PD-L1), has revolutionized cancer treatment. However, it is now well-known that PD-1/PD-L1 immunotherapy response is inconsistent among patients. The current challenge is to customize treatment regimens per patient, which could be possible if the PD-1/PD-L1 expression and dynamic landscape are known. With positron emission tomography (PET) imaging, it is possible to image these immune targets non-invasively and system-wide during therapy. A successful PET imaging tracer should meet specific criteria concerning target affinity, specificity, clearance rate and target-specific uptake, to name a few. The structural profile of such a tracer will define its properties and can be used to optimize tracers in development and design new ones. Currently, a range of PD-1/PD-L1-targeting PET tracers are available from different molecular categories that have shown impressive preclinical and clinical results, each with its own advantages and disadvantages. This review will provide an overview of current PET tracers targeting the PD-1/PD-L1 axis. Antibody, peptide, and antibody fragment tracers will be discussed with respect to their molecular characteristics and binding properties and ways to optimize them.
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Affiliation(s)
- Melinda Badenhorst
- Amsterdam UMC location Vrije Universiteit Amsterdam, Department of Radiology and Nuclear Medicine, De Boelelaan, Amsterdam, Netherlands
- Cancer Center Amsterdam, Imaging and Biomarkers, Amsterdam, Netherlands
| | - Albert D. Windhorst
- Amsterdam UMC location Vrije Universiteit Amsterdam, Department of Radiology and Nuclear Medicine, De Boelelaan, Amsterdam, Netherlands
- Cancer Center Amsterdam, Imaging and Biomarkers, Amsterdam, Netherlands
| | - Wissam Beaino
- Amsterdam UMC location Vrije Universiteit Amsterdam, Department of Radiology and Nuclear Medicine, De Boelelaan, Amsterdam, Netherlands
- Cancer Center Amsterdam, Imaging and Biomarkers, Amsterdam, Netherlands
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Gomes DEB, Yang B, Vanella R, Nash MA, Bernardi RC. Integrating Dynamic Network Analysis with AI for Enhanced Epitope Prediction in PD-L1:Affibody Interactions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.08.579577. [PMID: 38370725 PMCID: PMC10871313 DOI: 10.1101/2024.02.08.579577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Understanding binding epitopes involved in protein-protein interactions and accurately determining their structure is a long standing goal with broad applicability in industry and biomedicine. Although various experimental methods for binding epitope determination exist, these approaches are typically low throughput and cost intensive. Computational methods have potential to accelerate epitope predictions, however, recently developed artificial intelligence (AI)-based methods frequently fail to predict epitopes of synthetic binding domains with few natural homologs. Here we have developed an integrated method employing generalized-correlation-based dynamic network analysis on multiple molecular dynamics (MD) trajectories, initiated from AlphaFold2 Multimer structures, to unravel the structure and binding epitope of the therapeutic PD-L1:Affibody complex. Both AlphaFold2 and conventional molecular dynamics trajectory analysis alone each proved ineffectual in differentiating between two putative binding models referred to as parallel and perpendicular. However, our integrated approach based on dynamic network analysis showed that the perpendicular mode was significantly more stable. These predictions were validated using a suite of experimental epitope mapping protocols including cross linking mass spectrometry and next-generation sequencing-based deep mutational scanning. Our research highlights the potential of deploying dynamic network analysis to refine AI-based structure predictions for precise predictions of protein-protein interaction interfaces.
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Grindel BJ, Engel BJ, Ong JN, Srinivasamani A, Liang X, Zacharias NM, Bast RC, Curran MA, Takahashi TT, Roberts RW, Millward SW. Directed Evolution of PD-L1-Targeted Affibodies by mRNA Display. ACS Chem Biol 2022; 17:1543-1555. [PMID: 35611948 PMCID: PMC10691555 DOI: 10.1021/acschembio.2c00218] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Therapeutic monoclonal antibodies directed against PD-L1 (e.g., atezolizumab) disrupt PD-L1:PD-1 signaling and reactivate exhausted cytotoxic T-cells in the tumor compartment. Although anti-PD-L1 antibodies are successful as immune checkpoint inhibitor (ICI) therapeutics, there is still a pressing need to develop high-affinity, low-molecular-weight ligands for molecular imaging and diagnostic applications. Affibodies are small polypeptides (∼60 amino acids) that provide a stable molecular scaffold from which to evolve high-affinity ligands. Despite its proven utility in the development of imaging probes, this scaffold has never been optimized for use in mRNA display, a powerful in vitro selection platform incorporating high library diversity, unnatural amino acids, and chemical modification. In this manuscript, we describe the selection of a PD-L1-binding affibody by mRNA display. Following randomization of the 13 amino acids that define the binding interface of the well-described Her2 affibody, the resulting library was selected against recombinant human PD-L1 (hPD-L1). After four rounds, the enriched library was split and selected against either hPD-L1 or the mouse ortholog (mPD-L1). The dual target selection resulted in the identification of a human/mouse cross-reactive PD-L1 affibody (M1) with low nanomolar affinity for both targets. The M1 affibody bound with similar affinity to mPD-L1 and hPD-L1 expressed on the cell surface and inhibited signaling through the PD-L1:PD-1 axis at low micromolar concentrations in a cell-based functional assay. In vivo optical imaging with M1-Cy5 in an immune-competent mouse model of lymphoma revealed significant tumor uptake relative to a Cy5-conjugated Her2 affibody.
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Affiliation(s)
- Brian J. Grindel
- Department of Cancer Systems Imaging, MD Anderson Cancer Center, Houston, Texas, USA, 77054
| | - Brian J. Engel
- Department of Cancer Systems Imaging, MD Anderson Cancer Center, Houston, Texas, USA, 77054
| | - Justin N. Ong
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California, USA, 90089
| | | | - Xiaowen Liang
- Department of Experimental Therapeutics, MD Anderson Cancer Center, Houston, Texas, USA, 77054
| | - Niki M. Zacharias
- Department of Urology, MD Anderson Cancer Center, Houston, Texas, USA, 77054
| | - Robert C. Bast
- Department of Experimental Therapeutics, MD Anderson Cancer Center, Houston, Texas, USA, 77054
| | - Michael A. Curran
- Department of Immunology, MD Anderson Cancer Center, Houston, Texas, USA, 77054
| | - Terry T. Takahashi
- Department of Chemistry, University of Southern California, Los Angeles, California, USA, 90089
| | - Richard W. Roberts
- Department of Chemistry, University of Southern California, Los Angeles, California, USA, 90089
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California, USA, 90089
- USC Norris Comprehensive Cancer Center, Los Angeles, California, USA, 90089
| | - Steven W. Millward
- Department of Cancer Systems Imaging, MD Anderson Cancer Center, Houston, Texas, USA, 77054
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Kang BH, Lax BM, Wittrup KD. Yeast Surface Display for Protein Engineering: Library Generation, Screening, and Affinity Maturation. Methods Mol Biol 2022; 2491:29-62. [PMID: 35482183 DOI: 10.1007/978-1-0716-2285-8_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Yeast surface display is a powerful directed evolution method for developing and engineering protein molecules to attain desired properties. Here, updated protocols are presented for purposes of identification of lead binders and their affinity maturation. Large libraries are screened by magnetic bead selections followed by flow cytometric selections. Upon identification and characterization of single clones, their affinities are improved by an iterative process of mutagenesis and fluorescence-activated cell sorting.
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Affiliation(s)
- Byong H Kang
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Brianna M Lax
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - K Dane Wittrup
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA.
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Bridoux J, Broos K, Lecocq Q, Debie P, Martin C, Ballet S, Raes G, Neyt S, Vanhove C, Breckpot K, Devoogdt N, Caveliers V, Keyaerts M, Xavier C. Anti-human PD-L1 Nanobody for Immuno-PET Imaging: Validation of a Conjugation Strategy for Clinical Translation. Biomolecules 2020; 10:biom10101388. [PMID: 33003481 PMCID: PMC7599876 DOI: 10.3390/biom10101388] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 09/25/2020] [Accepted: 09/26/2020] [Indexed: 01/01/2023] Open
Abstract
Immune checkpoints, such as programmed death-ligand 1 (PD-L1), limit T-cell function and tumor cells use this ligand to escape the anti-tumor immune response. Treatments with monoclonal antibodies blocking these checkpoints have shown long-lasting responses, but only in a subset of patients. This study aims to develop a Nanobody (Nb)-based probe in order to assess human PD-L1 (hPD-L1) expression using positron emission tomography imaging, and to compare the influence of two different radiolabeling strategies, since the Nb has a lysine in its complementarity determining region (CDR), which may impact its affinity upon functionalization. The Nb has been conjugated with the NOTA chelator site-specifically via the Sortase-A enzyme or randomly on its lysines. [68Ga]Ga-NOTA-(hPD-L1) Nbs were obtained in >95% radiochemical purity. In vivo tumor targeting studies at 1 h 20 post-injection revealed specific tumor uptake of 1.89 ± 0.40%IA/g for the site-specific conjugate, 1.77 ± 0.29%IA/g for the random conjugate, no nonspecific organ targeting, and excretion via the kidneys and bladder. Both strategies allowed for easily obtaining 68Ga-labeled hPD-L1 Nbs in high yields. The two conjugates were stable and showed excellent in vivo targeting. Moreover, we proved that the random lysine-conjugation is a valid strategy for clinical translation of the hPD-L1 Nb, despite the lysine present in the CDR.
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Affiliation(s)
- Jessica Bridoux
- Medical Imaging Department (MIMA), In Vivo Cellular and Molecular Imaging Laboratory (ICMI), Vrije Universiteit Brussel, Laarbeeklaan 103, Building K, 1090 Brussels, Belgium; (P.D.); (N.D.); (V.C.); (M.K.); (C.X.)
- Correspondence: ; Tel.: +32-2-4774991
| | - Katrijn Broos
- Department of Biomedical Sciences, Laboratory for Molecular and Cellular Therapy (LCMT), Vrije Universiteit Brussel, Laarbeeklaan 103, Building D, 1090 Brussels, Belgium; (K.B.); (Q.L.); (K.B.)
| | - Quentin Lecocq
- Department of Biomedical Sciences, Laboratory for Molecular and Cellular Therapy (LCMT), Vrije Universiteit Brussel, Laarbeeklaan 103, Building D, 1090 Brussels, Belgium; (K.B.); (Q.L.); (K.B.)
| | - Pieterjan Debie
- Medical Imaging Department (MIMA), In Vivo Cellular and Molecular Imaging Laboratory (ICMI), Vrije Universiteit Brussel, Laarbeeklaan 103, Building K, 1090 Brussels, Belgium; (P.D.); (N.D.); (V.C.); (M.K.); (C.X.)
| | - Charlotte Martin
- Research Group of Organic Chemistry (ORGC), Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium; (C.M.); (S.B.)
| | - Steven Ballet
- Research Group of Organic Chemistry (ORGC), Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium; (C.M.); (S.B.)
| | - Geert Raes
- Sciences and Bioengineering Sciences, Cellular and Molecular Immunology laboratory (CMIM), Vrije Universiteit Brussel, Pleinlaan 2, Building F, 1050 Brussels, Belgium;
- Myeloid Cell Immunology Laboratory (MCI), VIB Inflammation Research Center, Technologiepark-Zwijnaarde 71, 9052 Ghent, Belgium
| | - Sara Neyt
- MOLECUBES NV, Ottergemsesteenweg Zuid 325, 9000 Ghent, Belgium;
| | - Christian Vanhove
- IBiTech-MEDISIP, Ghent University Hospital Site, Block B, Corneel Heymanslaan 10, 9000 Ghent, Belgium;
| | - Karine Breckpot
- Department of Biomedical Sciences, Laboratory for Molecular and Cellular Therapy (LCMT), Vrije Universiteit Brussel, Laarbeeklaan 103, Building D, 1090 Brussels, Belgium; (K.B.); (Q.L.); (K.B.)
| | - Nick Devoogdt
- Medical Imaging Department (MIMA), In Vivo Cellular and Molecular Imaging Laboratory (ICMI), Vrije Universiteit Brussel, Laarbeeklaan 103, Building K, 1090 Brussels, Belgium; (P.D.); (N.D.); (V.C.); (M.K.); (C.X.)
| | - Vicky Caveliers
- Medical Imaging Department (MIMA), In Vivo Cellular and Molecular Imaging Laboratory (ICMI), Vrije Universiteit Brussel, Laarbeeklaan 103, Building K, 1090 Brussels, Belgium; (P.D.); (N.D.); (V.C.); (M.K.); (C.X.)
- Nuclear Medicine Department, UZ Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium
| | - Marleen Keyaerts
- Medical Imaging Department (MIMA), In Vivo Cellular and Molecular Imaging Laboratory (ICMI), Vrije Universiteit Brussel, Laarbeeklaan 103, Building K, 1090 Brussels, Belgium; (P.D.); (N.D.); (V.C.); (M.K.); (C.X.)
- Nuclear Medicine Department, UZ Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium
| | - Catarina Xavier
- Medical Imaging Department (MIMA), In Vivo Cellular and Molecular Imaging Laboratory (ICMI), Vrije Universiteit Brussel, Laarbeeklaan 103, Building K, 1090 Brussels, Belgium; (P.D.); (N.D.); (V.C.); (M.K.); (C.X.)
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