1
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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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2
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Yang B, Gomes DEB, Liu Z, Santos MS, Li J, Bernardi RC, Nash MA. Engineering the Mechanical Stability of a Therapeutic Affibody/PD-L1 Complex by Anchor Point Selection. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.21.595133. [PMID: 38826272 PMCID: PMC11142103 DOI: 10.1101/2024.05.21.595133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Protein-protein complexes can vary in mechanical stability depending on the direction from which force is applied. Here we investigated the anisotropic mechanical stability of a molecular complex between a therapeutic non-immunoglobulin scaffold called Affibody and the extracellular domain of the immune checkpoint protein PD-L1. We used a combination of single-molecule AFM force spectroscopy (AFM-SMFS) with bioorthogonal clickable peptide handles, shear stress bead adhesion assays, molecular modeling, and steered molecular dynamics (SMD) simulations to understand the pulling point dependency of mechanostability of the Affibody:(PD-L1) complex. We observed diverse mechanical responses depending on the anchor point. For example, pulling from residue #22 on Affibody generated an intermediate unfolding event attributed to partial unfolding of PD-L1, while pulling from Affibody's N-terminus generated force-activated catch bond behavior. We found that pulling from residue #22 or #47 on Affibody generated the highest rupture forces, with the complex breaking at up to ~ 190 pN under loading rates of ~104-105 pN/sec, representing a ~4-fold increase in mechanostability as compared with low force N-terminal pulling. SMD simulations provided consistent tendencies in rupture forces, and through visualization of force propagation networks provided mechanistic insights. These results demonstrate how mechanostability of therapeutic protein-protein interfaces can be controlled by informed selection of anchor points within molecules, with implications for optimal bioconjugation strategies in drug delivery vehicles.
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Affiliation(s)
- Byeongseon Yang
- Institute for Physical Chemistry, Department of Chemistry, University of Basel, 4058 Basel, Switzerland
- Department of Biosystems Science and Engineering, ETH Zurich, 4056 Basel, Switzerland
| | - Diego E. B. Gomes
- Department of Physics, Auburn University, Auburn, Alabama 36849, United States
| | - Zhaowei Liu
- Institute for Physical Chemistry, Department of Chemistry, University of Basel, 4058 Basel, Switzerland
- Department of Biosystems Science and Engineering, ETH Zurich, 4056 Basel, Switzerland
- Present address: Department of Bionanoscience, Delft University of Technology, 2629HZ Delft, the Netherlands
| | - Mariana Sá Santos
- Institute for Physical Chemistry, Department of Chemistry, University of Basel, 4058 Basel, Switzerland
- Department of Biosystems Science and Engineering, ETH Zurich, 4056 Basel, Switzerland
| | - Jiajun Li
- Institute for Physical Chemistry, Department of Chemistry, University of Basel, 4058 Basel, Switzerland
- Department of Biosystems Science and Engineering, ETH Zurich, 4056 Basel, Switzerland
| | - Rafael C. Bernardi
- Department of Physics, Auburn University, Auburn, Alabama 36849, United States
| | - Michael A. Nash
- Institute for Physical Chemistry, Department of Chemistry, University of Basel, 4058 Basel, Switzerland
- Department of Biosystems Science and Engineering, ETH Zurich, 4056 Basel, Switzerland
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3
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Raskova Kafkova L, Mierzwicka JM, Chakraborty P, Jakubec P, Fischer O, Skarda J, Maly P, Raska M. NSCLC: from tumorigenesis, immune checkpoint misuse to current and future targeted therapy. Front Immunol 2024; 15:1342086. [PMID: 38384472 PMCID: PMC10879685 DOI: 10.3389/fimmu.2024.1342086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 01/17/2024] [Indexed: 02/23/2024] Open
Abstract
Non-small cell lung cancer (NSCLC) is largely promoted by a multistep tumorigenesis process involving various genetic and epigenetic alterations, which essentially contribute to the high incidence of mortality among patients with NSCLC. Clinical observations revealed that NSCLC also co-opts a multifaceted immune checkpoint dysregulation as an important driving factor in NSCLC progression and development. For example, a deregulated PI3K/AKT/mTOR pathway has been noticed in 50-70% of NSCLC cases, primarily modulated by mutations in key oncogenes such as ALK, EGFR, KRAS, and others. Additionally, genetic association studies containing patient-specific factors and local reimbursement criteria expose/reveal mutations in EGFR/ALK/ROS/BRAF/KRAS/PD-L1 proteins to determine the suitability of available immunotherapy or tyrosine kinase inhibitor therapy. Thus, the expression of such checkpoints on tumors and immune cells is pivotal in understanding the therapeutic efficacy and has been extensively studied for NSCLC treatments. Therefore, this review summarizes current knowledge in NSCLC tumorigenesis, focusing on its genetic and epigenetic intricacies, immune checkpoint dysregulation, and the evolving landscape of targeted therapies. In the context of current and future therapies, we emphasize the significance of antibodies targeting PD-1/PD-L1 and CTLA-4 interactions as the primary therapeutic strategy for immune system reactivation in NSCLC. Other approaches involving the promising potential of nanobodies, probodies, affibodies, and DARPINs targeting immune checkpoints are also described; these are under active research or clinical trials to mediate immune regulation and reduce cancer progression. This comprehensive review underscores the multifaceted nature, current state and future directions of NSCLC research and treatment.
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Affiliation(s)
- Leona Raskova Kafkova
- Department of Immunology, Faculty of Medicine and Dentistry, Palacky University Olomouc, Olomouc, Czechia
- Department of Immunology, University Hospital Olomouc, Olomouc, Czechia
| | - Joanna M. Mierzwicka
- Laboratory of Ligand Engineering, Institute of Biotechnology of the Czech Academy of Sciences, Vestec, Czechia
| | - Prosenjit Chakraborty
- Department of Immunology, Faculty of Medicine and Dentistry, Palacky University Olomouc, Olomouc, Czechia
| | - Petr Jakubec
- Department of Respiratory Diseases and Tuberculosis, University Hospital Olomouc, Olomouc, Czechia
| | - Ondrej Fischer
- Department of Respiratory Diseases and Tuberculosis, University Hospital Olomouc, Olomouc, Czechia
| | - Jozef Skarda
- Institute of Clinical and Molecular Pathology, Faculty of Medicine and Dentistry, Palacky University Olomouc, Olomouc, Czechia
- Department of Pathology, University Hospital Ostrava and Faculty of Medicine, University of Ostrava, Ostrava, Czechia
| | - Petr Maly
- Laboratory of Ligand Engineering, Institute of Biotechnology of the Czech Academy of Sciences, Vestec, Czechia
| | - Milan Raska
- Department of Immunology, Faculty of Medicine and Dentistry, Palacky University Olomouc, Olomouc, Czechia
- Department of Immunology, University Hospital Olomouc, Olomouc, Czechia
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4
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Krutzek F, Donat CK, Ullrich M, Stadlbauer S. Design, Synthesis, and Biological Evaluation of Small-Molecule-Based Radioligands with Improved Pharmacokinetic Properties for Imaging of Programmed Death Ligand 1. J Med Chem 2023; 66:15894-15915. [PMID: 38038981 PMCID: PMC10726354 DOI: 10.1021/acs.jmedchem.3c01355] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 11/11/2023] [Accepted: 11/15/2023] [Indexed: 12/02/2023]
Abstract
Small molecules offer some advantages for developing positron emission tomography (PET) tracers and are therefore a promising approach for imaging and therapy monitoring of programmed death ligand 1 (PD-L1) positive tumors. Here, we report six biphenyl PD-L1 radioligands using the NODA-GA-chelator for efficient copper-64 complexation. These radioligands contain varying numbers of sulfonic and/or phosphonic acid groups, serving as hydrophilizing units to lower the log D7.4 value down to -4.28. The binding affinities of compounds were evaluated using saturation binding and a real-time binding assay, with a highest binding affinity of 21 nM. Small-animal PET imaging revealed vastly different pharmacokinetic profiles depending on the quantity and type of hydrophilizing units. Of the investigated radioligands, [64Cu]Cu-3 showed the most favorable kinetics in vitro. This was also found in vivo, with a predominantly renal clearance and a specific uptake in the PD-L1-overexpressing tumor. With further modifications, this compound could be a promising candidate for the imaging of PD-L1 in the clinical setting.
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Affiliation(s)
- Fabian Krutzek
- Helmholtz-Zentrum
Dresden-Rossendorf, Institute of Radiopharmaceutical
Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Cornelius K. Donat
- Helmholtz-Zentrum
Dresden-Rossendorf, Institute of Radiopharmaceutical
Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Martin Ullrich
- Helmholtz-Zentrum
Dresden-Rossendorf, Institute of Radiopharmaceutical
Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Sven Stadlbauer
- Helmholtz-Zentrum
Dresden-Rossendorf, Institute of Radiopharmaceutical
Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
- Faculty
of Chemistry and Food Chemistry, School of Science, Technische Universität Dresden, Mommsenstraße 4, 01069 Dresden, Germany
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5
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Krutzek F, Donat CK, Stadlbauer S. Exploring Hydrophilic PD-L1 Radiotracers Utilizing Phosphonic Acids: Insights into Unforeseen Pharmacokinetics. Int J Mol Sci 2023; 24:15088. [PMID: 37894769 PMCID: PMC10606431 DOI: 10.3390/ijms242015088] [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] [Received: 09/14/2023] [Revised: 10/04/2023] [Accepted: 10/09/2023] [Indexed: 10/29/2023] Open
Abstract
Immune checkpoint inhibitor therapy targeting the PD-1/PD-L1 axis in cancer patients, is a promising oncological treatment. However, the number of non-responders remains high, causing a burden for the patient and the healthcare system. Consequently, a diagnostic tool to predict treatment outcomes would help with patient stratification. Molecular imaging provides said diagnostic tool by offering a whole-body quantitative assessment of PD-L1 expression, hence supporting therapy decisions. Four PD-L1 radioligand candidates containing a linker-chelator system for radiometalation, along with three hydrophilizing units-one sulfonic and two phosphonic acids-were synthesized. After labeling with 64Cu, log D7.4 values of less than -3.03 were determined and proteolytic stability confirmed over 94% intact compound after 48 h. Binding affinity was determined using two different assays, revealing high affinities up to 13 nM. µPET/CT imaging was performed in tumor-bearing mice to investigate PD-L1-specific tumor uptake and the pharmacokinetic profile of radioligands. These results yielded an unexpected in vivo distribution, such as low tumor uptake in PD-L1 positive tumors, high liver uptake, and accumulation in bone/bone marrow and potentially synovial spaces. These effects are likely caused by Ca2+-affinity and/or binding to macrophages. Despite phosphonic acids providing high water solubility, their incorporation must be carefully considered to avoid compromising the pharmacokinetic behavior of radioligands.
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Affiliation(s)
- Fabian Krutzek
- Helmholtz Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Medicinal Radiochemistry, Bautzner Landstraße 400, 01328 Dresden, Germany; (F.K.); (C.K.D.)
| | - Cornelius K. Donat
- Helmholtz Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Medicinal Radiochemistry, Bautzner Landstraße 400, 01328 Dresden, Germany; (F.K.); (C.K.D.)
| | - Sven Stadlbauer
- Helmholtz Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Medicinal Radiochemistry, Bautzner Landstraße 400, 01328 Dresden, Germany; (F.K.); (C.K.D.)
- School of Science, Faculty of Chemistry and Food Chemistry, Technical University Dresden, 01069 Dresden, Germany
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6
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Chen Y, Guo Y, Liu Z, Hu X, Hu M. An overview of current advances of PD-L1 targeting immuno-imaging in cancers. J Cancer Res Ther 2023; 19:866-875. [PMID: 37675710 DOI: 10.4103/jcrt.jcrt_88_23] [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: 09/08/2023]
Abstract
The programmed death protein 1/programmed cell death ligand 1 (PD-1/PD-L1) pathway plays a significant role in immune evasion. PD-1 or PD-L1 immune checkpoint inhibitors (ICIs) have become a standard treatment for multiple types of cancer. To date, PD-L1 has served as a biomarker for predicting the efficacy of ICIs in several cancers. The need to establish an effective detection method that could visualize PD-L1 expression and predict the efficacy of PD-1/PD-L1 ICIs has promoted a search for new imaging strategies. PD-L1-targeting immuno-imaging could provide a noninvasive, real-time, repeatable, dynamic, and quantitative assessment of the characteristics of all tumor lesions in individual patients. This study analyzed the existing evidence in the literature on PD-L1-based immuno-imaging (2015-2022). Original English-language articles were searched using PubMed and Google Scholar. Keywords, such as "PD-L1," "PET," "SPECT," "PET/CT," and "SPECT/CT," were used in various combinations. A total of nearly 50 preclinical and clinical studies of PD-L1-targeting immuno-imaging were selected, reviewed, and included in this study. Therefore, in this review, we conducted a study of the advances in PD-L1-targeting immuno-imaging for detecting the expression of PD-L1 and the efficacy of ICIs. We focused on the different types of PD-L1-targeting agents, including antibodies and small PD-L1-binding agents, and illustrated the strength and weakness of these probes. Furthermore, we summarized the trends in the development of PD-L1-targeting immuno-imaging, as well as the current challenges and future directions for clinical workflow.
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Affiliation(s)
- Yunhao Chen
- Department of Radiation Oncology, Shandong University Cancer Center; Department of Radiation Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China
| | - Yujiao Guo
- Department of Oncology, The Affiliated Hospital of Jining Medical University, Jining, China
| | - Zhiguo Liu
- Department of PET/CT Center, Shandong Cancer Hospital and Institute, Shandong First Medical University, Shandong Academy of Medical Sciences, Jinan, China
| | - Xiaokun Hu
- Department of the Interventional Medical Center, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - Man Hu
- Department of Radiation Oncology, Shandong University Cancer Center; Department of Radiation Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China
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7
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Khan F, Jones K, Lyon P. Immune checkpoint inhibition: a future guided by radiology. Br J Radiol 2023; 96:20220565. [PMID: 36752570 PMCID: PMC10321249 DOI: 10.1259/bjr.20220565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 01/04/2023] [Accepted: 01/29/2023] [Indexed: 02/09/2023] Open
Abstract
The limitation of the function of antitumour immune cells is a common hallmark of cancers that enables their survival. As such, the potential of immune checkpoint inhibition (ICI) acts as a paradigm shift in the treatment of a range of cancers but has not yet been fully capitalised. Combining minimally and non-invasive locoregional therapies offered by radiologists with ICI is now an active field of research with the aim of furthering therapeutic capabilities in medical oncology. In parallel to this impending advancement, the "imaging toolbox" available to radiologists is also growing, enabling more refined tumour characterisation as well as greater accuracy in evaluating responses to therapy. Options range from metabolite labelling to cellular localisation to immune checkpoint screening. It is foreseeable that these novel imaging techniques will be integrated into personalised treatment algorithms. This growth in the field must include updating the current standardised imaging criteria to ensure they are fit for purpose. Such criteria is crucial to both appropriately guide clinical decision-making regarding next steps of treatment, but also provide reliable prognosis. Quantitative approaches to these novel imaging techniques are also already being investigated to further optimise personalised therapeutic decision-making. The therapeutic potential of specific ICIs and locoregional therapies could be determined before administration thus limiting unnecessary side-effects whilst maintaining efficacy. Several radiological aspects of oncological care are advancing simultaneously. Therefore, it is essential that each development is assessed for clinical use and optimised to ensure the best treatment decisions are being offered to the patient. In this review, we discuss state of the art advances in novel functional imaging techniques in the field of immuno-oncology both pre-clinically and clinically.
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Affiliation(s)
- Faraaz Khan
- Foundation Doctor, Buckinghamshire Hospitals NHS Trust, Amersham, Buckinghamshire, United Kingdom
| | - Keaton Jones
- Academic Clinical Lecturer Nuffield Department of Surgical Sciences University of Oxford, Wellington Square, Oxford, United Kingdom
| | - Paul Lyon
- Consultant Radiologist, Department of Radiology, Oxford University Hospitals, Headington, Oxford, United Kingdom
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8
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Sharma G, Braga MC, Da Pieve C, Szopa W, Starzetz T, Plate KH, Kaspera W, Kramer-Marek G. Immuno-PET Imaging of Tumour PD-L1 Expression in Glioblastoma. Cancers (Basel) 2023; 15:3131. [PMID: 37370741 DOI: 10.3390/cancers15123131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 06/06/2023] [Accepted: 06/08/2023] [Indexed: 06/29/2023] Open
Abstract
There is no established method to assess the PD-L1 expression in brain tumours. Therefore, we investigated the suitability of affibody molecule (ZPD-L1) radiolabelled with F-18 (Al18F) and Ga-68 to measure the expression of PD-L1 in xenograft mouse models of GBM. Mice bearing subcutaneous and orthotopic tumours were imaged 1 h post-radioconjugate administration. Ex vivo biodistribution studies and immunohistochemistry (IHC) staining were performed. Tumoural PD-L1 expression and CD4+/CD8+ tumour-infiltrating lymphocytes were evaluated in human GBM specimens. ZPD-L1 was radiolabelled with radiochemical yields of 32.2 ± 4.4% (F-18) and 73.3 ± 1.8% (Ga-68). The cell-associated radioactivity in vitro was consistent with PD-L1 expression levels assessed with flow cytometry. In vivo imaging demonstrated that 18F-AlF-NOTA-ZPD-L1 can distinguish between PD-L1 high-expressing tumours (U87-MGvIII) and PD-L1-negative ones (H292PD-L1Ko). The radioconjugate was quickly cleared from the blood and normal tissues, allowing for high-contrast images of brain tumours as early as 1 h post-injection. 68Ga-NOTA-ZPD-L1 showed heterogeneous and diffuse accumulation that corresponded to the extensively infiltrating GCGR-E55 tumours involving contiguous lobes of the brain. Lastly, 39% of analysed GBM patient samples showed PD-L1+ staining of tumour cells that was associated with elevated levels of CD4+ and CD8+ lymphocytes. Our results suggest that the investigated radioconjugates are very promising agents with the potential to facilitate the future design of treatment regimens for GBM patients.
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Affiliation(s)
- Gitanjali Sharma
- Division of Radiotherapy and Imaging, Institute of Cancer Research, London SW7 3RP, UK
| | - Marta C Braga
- Division of Radiotherapy and Imaging, Institute of Cancer Research, London SW7 3RP, UK
| | - Chiara Da Pieve
- Division of Radiotherapy and Imaging, Institute of Cancer Research, London SW7 3RP, UK
| | - Wojciech Szopa
- Department of Neurosurgery, Medical University of Silesia, 41-200 Sosnowiec, Poland
| | - Tatjana Starzetz
- Edinger Institute, Institute of Neurology, 60528 Frankfurt, Germany
- German Consortium for Translational Cancer Research, DKTK, 69120 Heidelberg, Germany
| | - Karl H Plate
- Edinger Institute, Institute of Neurology, 60528 Frankfurt, Germany
- German Consortium for Translational Cancer Research, DKTK, 69120 Heidelberg, Germany
| | - Wojciech Kaspera
- Department of Neurosurgery, Medical University of Silesia, 41-200 Sosnowiec, Poland
| | - Gabriela Kramer-Marek
- Division of Radiotherapy and Imaging, Institute of Cancer Research, London SW7 3RP, UK
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9
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Radaram B, Glazer SE, Yang P, Li CW, Hung MC, Gammon ST, Alauddin M, Piwnica-Worms D. Evaluation of 89Zr-Labeled Anti-PD-L1 Monoclonal Antibodies Using DFO and Novel HOPO Analogues as Chelating Agents for Immuno-PET. ACS OMEGA 2023; 8:17181-17194. [PMID: 37214681 PMCID: PMC10193402 DOI: 10.1021/acsomega.3c01547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 03/24/2023] [Indexed: 05/24/2023]
Abstract
Programmed death ligand 1 (PD-L1) is a type 1 transmembrane immunosuppressive protein that is expressed on a wide range of cell types, including cancer cells. Anti-PD-L1 antibodies have revolutionized cancer therapy and have led to improved outcomes for subsets of cancer patients, including triple-negative breast cancer (TNBC) patients. As a result, PET imaging of PD-L1 protein expression in cancer patients has been explored for noninvasive detection of PD-L1 expressing tumors as well as monitoring response to anti-PD-L1 immune checkpoint therapy. Previous studies have indicated that the in vivo stability and in vivo target detection of antibody-based radio-conjugates can be dramatically affected by the chelator used. These reports demonstrated that the chelator HOPO diminishes 89Zr de-chelation compared to DFO. Herein, we report an improved HOPO synthesis and evaluated a series of novel analogues for thermal stability, serum stability, PD-L1-specific binding using the BT-549 TNBC cell line, PET imaging in vivo, as well as biodistribution of 89Zr-labeled anti-PD-L1 antibodies in BT-549 xenograft murine models. A new chelator, C5HOPO, demonstrated high stability in vitro and afforded effective PD-L1 targeting in vivovia immuno-PET. These results demonstrated that an improved HOPO chelator is an effective chelating agent that can be utilized to image therapeutically relevant targets in vivo.
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Affiliation(s)
- Bhasker Radaram
- Department
of Cancer Systems Imaging and Department of Molecular & Cellular
Oncology, The University of Texas MD Anderson
Cancer Center, Houston, Texas 77030, United States
| | - Sarah E. Glazer
- Department
of Cancer Systems Imaging and Department of Molecular & Cellular
Oncology, The University of Texas MD Anderson
Cancer Center, Houston, Texas 77030, United States
| | - Ping Yang
- Department
of Cancer Systems Imaging and Department of Molecular & Cellular
Oncology, The University of Texas MD Anderson
Cancer Center, Houston, Texas 77030, United States
| | - Chia-Wei Li
- Department
of Cancer Systems Imaging and Department of Molecular & Cellular
Oncology, The University of Texas MD Anderson
Cancer Center, Houston, Texas 77030, United States
| | - Mien-Chie Hung
- Department
of Cancer Systems Imaging and Department of Molecular & Cellular
Oncology, The University of Texas MD Anderson
Cancer Center, Houston, Texas 77030, United States
| | - Seth T. Gammon
- Department
of Cancer Systems Imaging and Department of Molecular & Cellular
Oncology, The University of Texas MD Anderson
Cancer Center, Houston, Texas 77030, United States
| | - Mian Alauddin
- Department
of Cancer Systems Imaging and Department of Molecular & Cellular
Oncology, The University of Texas MD Anderson
Cancer Center, Houston, Texas 77030, United States
| | - David Piwnica-Worms
- Department
of Cancer Systems Imaging and Department of Molecular & Cellular
Oncology, The University of Texas MD Anderson
Cancer Center, Houston, Texas 77030, United States
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10
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Krutzek F, Donat CK, Ullrich M, Zarschler K, Ludik MC, Feldmann A, Loureiro LR, Kopka K, Stadlbauer S. Design and Biological Evaluation of Small-Molecule PET-Tracers for Imaging of Programmed Death Ligand 1. Cancers (Basel) 2023; 15:cancers15092638. [PMID: 37174103 PMCID: PMC10177516 DOI: 10.3390/cancers15092638] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 04/18/2023] [Accepted: 05/03/2023] [Indexed: 05/15/2023] Open
Abstract
Noninvasive molecular imaging of the PD-1/PD-L1 immune checkpoint is of high clinical relevance for patient stratification and therapy monitoring in cancer patients. Here we report nine small-molecule PD-L1 radiotracers with solubilizing sulfonic acids and a linker-chelator system, designed by molecular docking experiments and synthesized according to a new, convergent synthetic strategy. Binding affinities were determined both in cellular saturation and real-time binding assay (LigandTracer), revealing dissociation constants in the single digit nanomolar range. Incubation in human serum and liver microsomes proved in vitro stability of these compounds. Small animal PET/CT imaging, in mice bearing PD-L1 overexpressing and PD-L1 negative tumors, showed moderate to low uptake. All compounds were cleared primarily through the hepatobiliary excretion route and showed a long circulation time. The latter was attributed to strong blood albumin binding effects, discovered during our binding experiments. Taken together, these compounds are a promising starting point for further development of a new class of PD-L1 targeting radiotracers.
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Affiliation(s)
- Fabian Krutzek
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Cornelius K Donat
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Martin Ullrich
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Kristof Zarschler
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Marie-Charlotte Ludik
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Anja Feldmann
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Liliana R Loureiro
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Klaus Kopka
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
- School of Science, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstraße 4, 01069 Dresden, Germany
- German Cancer Consortium (DKTK), Partner Site Dresden, Fetscherstraße 74, 01307 Dresden, Germany
- National Center for Tumor Diseases (NCT) Dresden, University Hospital Carl Gustav Carus, Fetscherstraße 74, 01307 Dresden, Germany
| | - Sven Stadlbauer
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
- School of Science, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstraße 4, 01069 Dresden, Germany
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11
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Radiochemistry with {Al18F}2+: Current status and optimization perspectives for efficient radiofluorination by complexation. Coord Chem Rev 2023. [DOI: 10.1016/j.ccr.2023.215028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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12
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García Melián MF, Moreno M, Cerecetto H, Calzada V. Aptamer-Based Immunotheranostic Strategies. Cancer Biother Radiopharm 2023; 38:246-255. [PMID: 36603108 DOI: 10.1089/cbr.2022.0064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The escape from immune surveillance is a hallmark of cancer progression. The classic immune checkpoint molecules PD-1, PD-L1, CTLA-4, LAG-3, TIM-3 novel ones are part of a sophisticated system of up- and downmodulation of the immune system, which is unregulated in cancer. In recent years, there have been remarkable advances in the development of targeting strategies, focused principally on immunotherapies aiming at blocking those molecules involved in the evasion of the immune system. However, there are still challenges to predicting their efficacy due to the wide heterogeneity of clinical responses. Thus, there is a need to develop new strategies, and theranostics has much to contribute in this field. Besides that, aptamers have emerged as promising molecules with the potential to generate a huge impact in the immunotheranostic field. They are single-stranded oligonucleotides with a unique self-folding tridimensional structure, with high affinity and specificity for the target. In particular, their small size and physicochemical characteristics make them a versatile tool for designing theranostic strategies. Here, we review the progress in theranostic strategies based on aptamers against immune checkpoints, and highlight the potential of those approaches.
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Affiliation(s)
- María Fernanda García Melián
- Área de Radiofarmacia, Centro de Investigaciones Nucleares, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - María Moreno
- Departamento de Desarrollo Biotecnológico, Instituto de Higiene, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Hugo Cerecetto
- Área de Radiofarmacia, Centro de Investigaciones Nucleares, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Victoria Calzada
- Área de Radiofarmacia, Centro de Investigaciones Nucleares, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
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13
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Zhang Y, Ding Y, Li N, Wang S, Zhou S, Li R, Yang H, Li W, Qu J. Noninvasive Imaging of Tumor PD-L1 Expression Using [ 99mTc]Tc-Labeled KN035 with SPECT/CT. Mol Pharm 2023; 20:690-700. [PMID: 36541699 DOI: 10.1021/acs.molpharmaceut.2c00874] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Programmed cell death protein-1/ligand-1 (PD-1/PD-L1) checkpoint blockade is a major breakthrough in cancer therapy, but identifying patients likely to benefit from this therapy remains challenging. Immunohistochemistry is not informative about PD-L1 expression heterogeneity because of the limitations of invasive tissue collection. Noninvasive SPECT imaging is an approach to patient selection and therapeutic monitoring by assessing the PD-L1 status throughout the whole body. Here, we radiolabeled a single-domain PD-L1 antibody with technetium-99m (99mTc) for immune-SPECT imaging to evaluate its feasibility of detecting PD-L1 expression. The radiochemical purity of [99mTc]Tc-HYNIC-KN035 was 99.40 ± 0.11% with a specific activity of 2.68 MBq/μg. [99mTc]Tc-HYNIC-KN035 displayed a high PD-L1 specificity both in vitro and in vivo and showed a high specific affinity for PD-L1 with an equilibrium dissociation constant (KD) of 31.04 nM. The binding of [99mTc]Tc-HYNIC-KN035 to H1975 cells (high expression of PD-L1) was much higher than to A549 cells (low expression of PD-L1). SPECT/CT imaging showed that H1975 tumors were visualized at 4 h post-injection and became clearer with time. However, mild tumor uptake was observed in A549 tumors and H1975 tumors of the blocking group at all time points. The uptake value of [99mTc]Tc-HYNIC-KN035 in H1975 tumors was increased continuously from 9.68 ± 0.91% ID/g at 4 h to 13.31 ± 2.23% ID/g at 24 h post-injection, which was higher than in A549 tumors with %ID/g of 4.59 ± 0.76 and 5.54 ± 0.28 at 4 and 24 h post-injection, respectively. These specific bindings were confirmed by blocking studies. [99mTc]Tc-HYNIC-KN035 can be synthesized easily and specifically targeted to PD-L1 in the tumor environment, allowing PD-L1 expression assessment noninvasively and dynamically with SPECT/CT imaging.
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Affiliation(s)
- Yingying Zhang
- Department of Nuclear Medicine, The Affiliated Cancer Hospital of Zhengzhou University & Henan Cancer Hospital, Zhengzhou 450008, China
| | - Ying Ding
- Department of Nuclear Medicine, The Affiliated Cancer Hospital of Zhengzhou University & Henan Cancer Hospital, Zhengzhou 450008, China.,Department of Nuclear Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.,Hubei Province Key Laboratory of Molecular Imaging, Wuhan 430022, China.,Key Laboratory of Biological Targeted Therapy, The Ministry of Education, Wuhan 430022, China
| | - Ning Li
- Department of Nuclear Medicine, The Affiliated Cancer Hospital of Zhengzhou University & Henan Cancer Hospital, Zhengzhou 450008, China
| | - Sen Wang
- Department of Nuclear Medicine, The Affiliated Cancer Hospital of Zhengzhou University & Henan Cancer Hospital, Zhengzhou 450008, China
| | - Si Zhou
- Department of Nuclear Medicine, The Affiliated Cancer Hospital of Zhengzhou University & Henan Cancer Hospital, Zhengzhou 450008, China
| | - Ruping Li
- Department of Nuclear Medicine, The Affiliated Cancer Hospital of Zhengzhou University & Henan Cancer Hospital, Zhengzhou 450008, China
| | - Hui Yang
- Department of Nuclear Medicine, The Affiliated Cancer Hospital of Zhengzhou University & Henan Cancer Hospital, Zhengzhou 450008, China
| | - Wenliang Li
- Department of Nuclear Medicine, The Affiliated Cancer Hospital of Zhengzhou University & Henan Cancer Hospital, Zhengzhou 450008, China
| | - Jinrong Qu
- Department of Radiology, The Affiliated Cancer Hospital of Zhengzhou University & Henan Cancer Hospital, Zhengzhou 450008, China
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14
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Liang Z, Hu X, Hu H, Wang P, Cai J. Novel small 99mTc-labeled affibody molecular probe for PD-L1 receptor imaging. Front Oncol 2022; 12:1017737. [PMID: 36387113 PMCID: PMC9643847 DOI: 10.3389/fonc.2022.1017737] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 10/10/2022] [Indexed: 10/07/2023] Open
Abstract
OBJECTIVE The in vivo imaging of programmed death ligand 1 (PD-L1) can monitor changes in PD-L1 expression and guide programmed death 1 (PD-1) or PD-L1-targeted immune checkpoint therapy. A 99mTc-labeled affibody molecular probe targeting the PD-L1 receptor was prepared and evaluated its tracing effect in PD-L1-overexpressing colon cancer. METHODS The PD-L1 affibody was prepared by genetic recombineering. The 99mTc labeling of the affibody was achieved by sodium glucoheptonate and an SnCl2 labeling system. The labeling rate, radiochemical purity, and stability in vitro were determined by instant thin-layer chromatography; MC38-B7H1 (PD-L1-positive) and MC38 (PD-L1-negative) colon cancer cells were used to evaluate its affinity to PD-L1 by cell-binding experiments. The biodistribution of the 99mTc-labeled affibody molecular probe was then determined in C57BL/6J mice bearing MC38-B7H1 tumors, and tumor targeting was assessed in C57BL/6J mice with MC38-B7H1, MC38 double xenografts. RESULT The nondecayed corrected yield of the 99mTc-PD-L1 affibody molecular probe was 95.95% ± 1.26%, and showed good stability both in phosphate-buffered saline (PBS) and fetal bovine serum within 6 h. The affinity of the 99mTc-PD-L1 affibody molecular probe for cell-binding assays was 10.02 nmol/L. Single photon emission-computed tomography imaging showed a rapid uptake of the tracer in PD-L1-positive tumors and very little tracer retention in PD-L1-negative control tumors. The tracer was significantly retained in the kidneys and bladder, suggesting that it is mainly excreted through the urinary system. Heart, liver, lung, and muscle tissue showed no significant radioactive retention. The biodistribution in vitro also showed significant renal retention, a small amount of uptake in the thyroid and gastrointestinal tract, and rapid blood clearance, and the tumor-to-blood radioactivity uptake ratio peaked 120 min after drug injection. CONCLUSION The 99mTc-PD-L1 affibody molecular probe that we prepared can effectively target to PD-L1-positive tumors imaging in vivo, and clear in blood quickly, with no obvious toxic side effects, which is expected to become a new type of tracer for detecting PD-L1 expression in tumors.
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Affiliation(s)
| | | | | | - Pan Wang
- Department of Nuclear Medicine, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou, China
| | - Jiong Cai
- Department of Nuclear Medicine, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou, China
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15
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Ge S, Jia T, Li J, Zhang B, Sang S, Deng S. Molecular imaging of immune checkpoints in oncology: Current and future applications. Cancer Lett 2022; 548:215896. [PMID: 36041658 DOI: 10.1016/j.canlet.2022.215896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 08/19/2022] [Indexed: 11/02/2022]
Abstract
Immune checkpoint (IC) blockade therapy has become the first-line treatment for various cancers. However, the low response rate and acquired drug resistance severely restrict the clinical application of immune checkpoint inhibitors (ICIs). Nuclide molecular imaging of ICs can provide non-invasive and whole-body visualization of in vivo IC dynamic biodistribution. Therefore, molecular imaging of ICs can predict and monitor responses to ICIs as a complementary tool to existing immunohistochemical techniques. Herein, we outlined the current status and recent advances in molecular imaging of the "first-generation" and "next-generation" ICs in preclinical and clinical studies.
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Affiliation(s)
- Shushan Ge
- Department of Nuclear Medicine, The First Affiliated Hospital of Soochow University, Suzhou, 215000, China; NHC Key Laboratory of Nuclear Technology Medical Transformation, Mianyang Central Hospital, Mianyang, 621099, China
| | - Tongtong Jia
- Department of Nuclear Medicine, The First Affiliated Hospital of Soochow University, Suzhou, 215000, China
| | - Jihui Li
- Department of Nuclear Medicine, The First Affiliated Hospital of Soochow University, Suzhou, 215000, China
| | - Bing Zhang
- Department of Nuclear Medicine, The First Affiliated Hospital of Soochow University, Suzhou, 215000, China
| | - Shibiao Sang
- Department of Nuclear Medicine, The First Affiliated Hospital of Soochow University, Suzhou, 215000, China.
| | - Shengming Deng
- Department of Nuclear Medicine, The First Affiliated Hospital of Soochow University, Suzhou, 215000, China; NHC Key Laboratory of Nuclear Technology Medical Transformation, Mianyang Central Hospital, Mianyang, 621099, China.
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16
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Liu WL, Zhang YQ, Li LT, Zhu YY, Ming ZH, Chen WL, Yang RQ, Li RH, Chen M, Zhang GJ. Application of molecular imaging in immune checkpoints therapy: From response assessment to prognosis prediction. Crit Rev Oncol Hematol 2022; 176:103746. [PMID: 35752425 DOI: 10.1016/j.critrevonc.2022.103746] [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] [Received: 01/27/2022] [Revised: 05/30/2022] [Accepted: 06/13/2022] [Indexed: 11/17/2022] Open
Abstract
Recently, immune checkpoint therapy (ICT) represented by programmed cell death1 (PD-1) and its major ligands, programmed death ligand 1 (PD-L1), has achieved significant success. Detection of PD-L1 by immunohistochemistry (IHC) is a classic method to guide the treatment of ICT patients. However, PD-L1 expression in the tumor microenvironment is highly complex. Thus, PD-L1 IHC is inadequate to fully understand the relevance of PD-L1 levels in the whole body and their dynamics to improve therapeutic outcomes. Intriguingly, numerous studies have revealed that molecular imaging technologies could potentially meet this need. Therefore, the purpose of this narrative review is to summarize the preclinical and clinical application of ICT guided by molecular imaging technology, and to explore the future opportunities and practical difficulties of these innovations.
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Affiliation(s)
- Wan-Ling Liu
- Department of Breast-Thyroid-Surgery and Cancer Center, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, 2000 East Xiang'an Road, Xiamen, China; Fujian Key Laboratory of Precision Diagnosis and Treatment in Breast Cancer (Xiang'an Hospital of Xiamen University), 2000 East Xiang'an Road, Xiamen, China; Xiamen Key Laboratory for Endocrine Related Cancer Precision Medicine, Xiang'an Hospital of Xiamen University, 2000 East Xiang'an Road, Xiamen, China; Xiamen Research Center of Clinical Medicine in Breast & Thyroid Cancers, 2000 East Xiang'an Road, Xiamen, China
| | - Yong-Qu Zhang
- Department of Breast-Thyroid-Surgery and Cancer Center, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, 2000 East Xiang'an Road, Xiamen, China; Fujian Key Laboratory of Precision Diagnosis and Treatment in Breast Cancer (Xiang'an Hospital of Xiamen University), 2000 East Xiang'an Road, Xiamen, China; Xiamen Key Laboratory for Endocrine Related Cancer Precision Medicine, Xiang'an Hospital of Xiamen University, 2000 East Xiang'an Road, Xiamen, China; Xiamen Research Center of Clinical Medicine in Breast & Thyroid Cancers, 2000 East Xiang'an Road, Xiamen, China
| | - Liang-Tao Li
- Department of Breast-Thyroid-Surgery and Cancer Center, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, 2000 East Xiang'an Road, Xiamen, China; Fujian Key Laboratory of Precision Diagnosis and Treatment in Breast Cancer (Xiang'an Hospital of Xiamen University), 2000 East Xiang'an Road, Xiamen, China; Xiamen Key Laboratory for Endocrine Related Cancer Precision Medicine, Xiang'an Hospital of Xiamen University, 2000 East Xiang'an Road, Xiamen, China; Xiamen Research Center of Clinical Medicine in Breast & Thyroid Cancers, 2000 East Xiang'an Road, Xiamen, China
| | - Yuan-Yuan Zhu
- Department of Breast-Thyroid-Surgery and Cancer Center, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, 2000 East Xiang'an Road, Xiamen, China; Fujian Key Laboratory of Precision Diagnosis and Treatment in Breast Cancer (Xiang'an Hospital of Xiamen University), 2000 East Xiang'an Road, Xiamen, China; Xiamen Key Laboratory for Endocrine Related Cancer Precision Medicine, Xiang'an Hospital of Xiamen University, 2000 East Xiang'an Road, Xiamen, China; Xiamen Research Center of Clinical Medicine in Breast & Thyroid Cancers, 2000 East Xiang'an Road, Xiamen, China
| | - Zi-He Ming
- Department of Breast-Thyroid-Surgery and Cancer Center, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, 2000 East Xiang'an Road, Xiamen, China; Fujian Key Laboratory of Precision Diagnosis and Treatment in Breast Cancer (Xiang'an Hospital of Xiamen University), 2000 East Xiang'an Road, Xiamen, China; Xiamen Key Laboratory for Endocrine Related Cancer Precision Medicine, Xiang'an Hospital of Xiamen University, 2000 East Xiang'an Road, Xiamen, China; Xiamen Research Center of Clinical Medicine in Breast & Thyroid Cancers, 2000 East Xiang'an Road, Xiamen, China
| | - Wei-Ling Chen
- Department of Breast-Thyroid-Surgery and Cancer Center, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, 2000 East Xiang'an Road, Xiamen, China; Fujian Key Laboratory of Precision Diagnosis and Treatment in Breast Cancer (Xiang'an Hospital of Xiamen University), 2000 East Xiang'an Road, Xiamen, China; Xiamen Key Laboratory for Endocrine Related Cancer Precision Medicine, Xiang'an Hospital of Xiamen University, 2000 East Xiang'an Road, Xiamen, China; Xiamen Research Center of Clinical Medicine in Breast & Thyroid Cancers, 2000 East Xiang'an Road, Xiamen, China
| | - Rui-Qin Yang
- Department of Breast-Thyroid-Surgery and Cancer Center, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, 2000 East Xiang'an Road, Xiamen, China; Fujian Key Laboratory of Precision Diagnosis and Treatment in Breast Cancer (Xiang'an Hospital of Xiamen University), 2000 East Xiang'an Road, Xiamen, China; Xiamen Key Laboratory for Endocrine Related Cancer Precision Medicine, Xiang'an Hospital of Xiamen University, 2000 East Xiang'an Road, Xiamen, China; Xiamen Research Center of Clinical Medicine in Breast & Thyroid Cancers, 2000 East Xiang'an Road, Xiamen, China
| | - Rong-Hui Li
- Fujian Key Laboratory of Precision Diagnosis and Treatment in Breast Cancer (Xiang'an Hospital of Xiamen University), 2000 East Xiang'an Road, Xiamen, China; Department of Medical Oncology, Xiang'an Hospital of Xiamen University, 2000 East Xiang'an Road, Xiamen, China
| | - Min Chen
- Fujian Key Laboratory of Precision Diagnosis and Treatment in Breast Cancer (Xiang'an Hospital of Xiamen University), 2000 East Xiang'an Road, Xiamen, China; Xiamen Key Laboratory for Endocrine Related Cancer Precision Medicine, Xiang'an Hospital of Xiamen University, 2000 East Xiang'an Road, Xiamen, China.
| | - Guo-Jun Zhang
- Department of Breast-Thyroid-Surgery and Cancer Center, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, 2000 East Xiang'an Road, Xiamen, China; Fujian Key Laboratory of Precision Diagnosis and Treatment in Breast Cancer (Xiang'an Hospital of Xiamen University), 2000 East Xiang'an Road, Xiamen, China; Xiamen Key Laboratory for Endocrine Related Cancer Precision Medicine, Xiang'an Hospital of Xiamen University, 2000 East Xiang'an Road, Xiamen, China; Xiamen Research Center of Clinical Medicine in Breast & Thyroid Cancers, 2000 East Xiang'an Road, Xiamen, China; Cancer Research Center, School of Medicine, Xiamen University, 4221 South Xiang'an Road, Xiamen, China.
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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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Krutzek F, Kopka K, Stadlbauer S. Development of Radiotracers for Imaging of the PD-1/PD-L1 Axis. Pharmaceuticals (Basel) 2022; 15:ph15060747. [PMID: 35745666 PMCID: PMC9228425 DOI: 10.3390/ph15060747] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 06/08/2022] [Accepted: 06/09/2022] [Indexed: 11/24/2022] Open
Abstract
Immune checkpoint inhibitor (ICI) therapy has emerged as a major treatment option for a variety of cancers. Among the immune checkpoints addressed, the programmed death receptor 1 (PD-1) and its ligand PD-L1 are the key targets for an ICI. PD-L1 has especially been proven to be a reproducible biomarker allowing for therapy decisions and monitoring therapy success. However, the expression of PD-L1 is not only heterogeneous among and within tumor lesions, but the expression is very dynamic and changes over time. Immunohistochemistry, which is the standard diagnostic tool, can only inadequately address these challenges. On the other hand, molecular imaging techniques such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT) provide the advantage of a whole-body scan and therefore fully address the issue of the heterogeneous expression of checkpoints over time. Here, we provide an overview of existing PET, SPECT, and optical imaging (OI) (radio)tracers for the imaging of the upregulation levels of PD-1 and PD-L1. We summarize the preclinical and clinical data of the different molecule classes of radiotracers and discuss their respective advantages and disadvantages. At the end, we show possible future directions for developing new radiotracers for the imaging of PD-1/PD-L1 status in cancer patients.
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Affiliation(s)
- Fabian Krutzek
- Department of Translational TME Ligands, Institute of Radiopharmaceutical Cancer Research, Helmholtz Center Dresden-Rossendorf, 01328 Dresden, Germany; (F.K.); (K.K.)
| | - Klaus Kopka
- Department of Translational TME Ligands, Institute of Radiopharmaceutical Cancer Research, Helmholtz Center Dresden-Rossendorf, 01328 Dresden, Germany; (F.K.); (K.K.)
- School of Science, Faculty of Chemistry and Food Chemistry, Technical University Dresden, 01069 Dresden, Germany
- German Cancer Consortium (DKTK), Partner Site Dresden, 01307 Dresden, Germany
- National Center for Tumor Diseases (NCT), Partner Site Dresden, University Cancer Cancer (UCC), 01307 Dresden, Germany
| | - Sven Stadlbauer
- Department of Translational TME Ligands, Institute of Radiopharmaceutical Cancer Research, Helmholtz Center Dresden-Rossendorf, 01328 Dresden, Germany; (F.K.); (K.K.)
- Correspondence:
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Ridge NA, Rajkumar-Calkins A, Dudzinski SO, Kirschner AN, Newman NB. Radiopharmaceuticals as Novel Immune System Tracers. Adv Radiat Oncol 2022; 7:100936. [PMID: 36148374 PMCID: PMC9486425 DOI: 10.1016/j.adro.2022.100936] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 02/07/2022] [Indexed: 11/17/2022] Open
Abstract
Immune checkpoint inhibitors (ICIs) have transformed the treatment paradigms for multiple cancers. However, ICI therapy often fails to generate measurable and sustained antitumor responses, and clinically meaningful benefits remain limited to a small proportion of overall patients. A major obstacle to development and effective application of novel therapeutic regimens is optimized patient selection and response assessment. Noninvasive imaging using novel immunoconjugate radiopharmaceuticals (immuno–positron emission tomography and immuno-single-photon emission computed tomography) can assess for expression of cell surface immune markers, such as programmed cell death protein ligand-1 (PD-L1), akin to a virtual biopsy. This emerging technology has the potential to provide clinicians with a quantitative, specific, real-time evaluation of immunologic responses relative to cancer burden in the body. We discuss the rationale for using noninvasive molecular imaging of the programmed cell death protein-1 and PD-L1 axis as a biomarker for immunotherapy and summarize the current status of preclinical and clinical studies examining PD-L1 immuno–positron emission tomography. The strategies described in this review provide insight for future clinical trials exploring the use of immune checkpoint imaging as a biomarker for both ICI and radiation therapy, and for the rational design of combinatorial therapeutic regimens.
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Yao Y, Zhou X, Zhang A, Ma X, Zhu H, Yang Z, Li N. The role of PET molecular imaging in immune checkpoint inhibitor therapy in lung cancer: Precision medicine and visual monitoring. Eur J Radiol 2022; 149:110200. [DOI: 10.1016/j.ejrad.2022.110200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/13/2022] [Accepted: 02/07/2022] [Indexed: 11/03/2022]
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21
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Yang Y, Wang C, Wang Y, Sun Y, Huang X, Huang M, Xu H, Fan H, Chen D, Zhao F. Dose escalation biodistribution, positron emission tomography/computed tomography imaging and dosimetry of a highly specific radionuclide-labeled non-blocking nanobody. EJNMMI Res 2021; 11:113. [PMID: 34718889 PMCID: PMC8557220 DOI: 10.1186/s13550-021-00854-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 09/12/2021] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Immunotherapy is a valuable option for cancer treatment, and the curative effect of anti-PD-1/PD-L1 therapy correlates closely with PD-L1 expression levels. Positron emission tomography (PET) imaging of PD-L1 expression is feasible using 68Ga-NOTA-Nb109 nanobody. 68Ga-NOTA-Nb109 was generated by radionuclide (68Ga) labeling of Nb109 using a NOTA chelator. To facilitate clinical trials, we explored the optimal dose range of 68Ga-NOTA-Nb109 in BALB/c A375-hPD-L1 tumor-burdened nude mice and C57-hPD-L1 transgenic MC38-hPD-L1 tumor-burdened mice by administration of a single intravenous dose of 68Ga-NOTA-Nb109 and confirmed the dose in cynomolgus monkeys. The biodistribution data of cynomolgus monkey PET images were extrapolated to estimate the radiation dose for the adult male and female using OLINDA2.1 software. RESULTS 68Ga-NOTA-Nb109 was stable in physiologic media and human serum. Ex vivo biodistribution studies showed rapid and specific uptake in A375-hPD-L1 or MC38-hPD-L1 tumors. The estimated ED50 was approximately 5.4 µg in humanized mice. The injected mass (0.3-100 µg in nude mice and approximately 1-100 µg in humanized mice) greatly influenced the general biodistribution, with a better tumor-to-background ratio acquired at lower doses of Nb109 (0.3-10 µg in nude mice and approximately 1 µg in humanized mice), indicating maximum uptake in tumors at administered mass doses below the estimated ED50. Therefore, a single 15-μg/kg dose was adopted for the PET/CT imaging in the cynomolgus monkey. The highest specific and persistent uptake of the tracer was detected in the spleen, except the levels in the kidney and urine bladder, which was related to metabolism and excretion. The spleen-to-muscle ratio of the tracer exceeded 10 from immediately to 4 h after administration, indicating that the dose was appropriate. The estimated effective dose was calculated to yield a radiation dose of 4.1 mSv to a patient after injecting 185 MBq of 68Ga-NOTA-Nb109. CONCLUSION 68Ga-NOTA-Nb109 showed specific accumulation in hPD-L1 xenografts in ex vivo biodistribution studies and monkey PET/CT imaging. The dose escalation distribution data provided a recommended dose range for further use, and the safety of the tracer was confirmed in dosimetry studies.
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Affiliation(s)
- Yanling Yang
- Key Laboratory of Molecular Pharmacology and Drug Evaluation, Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, School of Pharmacy, Yantai University, Yantai, 264005, People's Republic of China
| | - Chao Wang
- SmartNuclide Biopharma Co. Ltd, 218 Xinghu St., BioBAY A4-202, Suzhou Industrial Park, Suzhou, 215123, People's Republic of China
| | - Yan Wang
- Department of Clinical Pharmacology, First Affiliated Hospital of Soochow University, 899 Pinghai Road, Gusu District, Suzhou, 215006, People's Republic of China
| | - Yan Sun
- SmartNuclide Biopharma Co. Ltd, 218 Xinghu St., BioBAY A4-202, Suzhou Industrial Park, Suzhou, 215123, People's Republic of China
| | - Xing Huang
- Zhejiang Provincial Key Laboratory of Pancreatic Disease, Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310058, People's Republic of China
| | - Minzhou Huang
- Department of Clinical Pharmacology, First Affiliated Hospital of Soochow University, 899 Pinghai Road, Gusu District, Suzhou, 215006, People's Republic of China
| | - Hui Xu
- Key Laboratory of Molecular Pharmacology and Drug Evaluation, Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, School of Pharmacy, Yantai University, Yantai, 264005, People's Republic of China
| | - Huaying Fan
- Key Laboratory of Molecular Pharmacology and Drug Evaluation, Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, School of Pharmacy, Yantai University, Yantai, 264005, People's Republic of China
| | - Daquan Chen
- Key Laboratory of Molecular Pharmacology and Drug Evaluation, Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, School of Pharmacy, Yantai University, Yantai, 264005, People's Republic of China.
| | - Feng Zhao
- Key Laboratory of Molecular Pharmacology and Drug Evaluation, Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, School of Pharmacy, Yantai University, Yantai, 264005, People's Republic of China.
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Liberini V, Laudicella R, Capozza M, Huellner MW, Burger IA, Baldari S, Terreno E, Deandreis D. The Future of Cancer Diagnosis, Treatment and Surveillance: A Systemic Review on Immunotherapy and Immuno-PET Radiotracers. Molecules 2021; 26:2201. [PMID: 33920423 PMCID: PMC8069316 DOI: 10.3390/molecules26082201] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 04/07/2021] [Accepted: 04/09/2021] [Indexed: 12/12/2022] Open
Abstract
Immunotherapy is an effective therapeutic option for several cancers. In the last years, the introduction of checkpoint inhibitors (ICIs) has shifted the therapeutic landscape in oncology and improved patient prognosis in a variety of neoplastic diseases. However, to date, the selection of the best patients eligible for these therapies, as well as the response assessment is still challenging. Patients are mainly stratified using an immunohistochemical analysis of the expression of antigens on biopsy specimens, such as PD-L1 and PD-1, on tumor cells, on peritumoral immune cells and/or in the tumor microenvironment (TME). Recently, the use and development of imaging biomarkers able to assess in-vivo cancer-related processes are becoming more important. Today, positron emission tomography (PET) with 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) is used routinely to evaluate tumor metabolism, and also to predict and monitor response to immunotherapy. Although highly sensitive, FDG-PET in general is rather unspecific. Novel radiopharmaceuticals (immuno-PET radiotracers), able to identify specific immune system targets, are under investigation in pre-clinical and clinical settings to better highlight all the mechanisms involved in immunotherapy. In this review, we will provide an overview of the main new immuno-PET radiotracers in development. We will also review the main players (immune cells, tumor cells and molecular targets) involved in immunotherapy. Furthermore, we report current applications and the evidence of using [18F]FDG PET in immunotherapy, including the use of artificial intelligence (AI).
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MESH Headings
- Antineoplastic Agents, Immunological/therapeutic use
- Artificial Intelligence
- B7-H1 Antigen/genetics
- B7-H1 Antigen/immunology
- Fluorodeoxyglucose F18/administration & dosage
- Fluorodeoxyglucose F18/chemistry
- Gene Expression Regulation, Neoplastic/drug effects
- Humans
- Immune Checkpoint Inhibitors/chemistry
- Immune Checkpoint Inhibitors/metabolism
- Immunotherapy, Adoptive/methods
- Killer Cells, Natural/drug effects
- Killer Cells, Natural/immunology
- Killer Cells, Natural/pathology
- Neoplasms/diagnostic imaging
- Neoplasms/genetics
- Neoplasms/immunology
- Neoplasms/therapy
- Positron-Emission Tomography/methods
- Programmed Cell Death 1 Receptor/genetics
- Programmed Cell Death 1 Receptor/immunology
- Radiopharmaceuticals/administration & dosage
- Radiopharmaceuticals/chemical synthesis
- Signal Transduction
- T-Lymphocytes, Cytotoxic/drug effects
- T-Lymphocytes, Cytotoxic/immunology
- T-Lymphocytes, Cytotoxic/pathology
- T-Lymphocytes, Regulatory/drug effects
- T-Lymphocytes, Regulatory/immunology
- T-Lymphocytes, Regulatory/pathology
- Tumor Microenvironment/drug effects
- Tumor Microenvironment/genetics
- Tumor Microenvironment/immunology
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Affiliation(s)
- Virginia Liberini
- Department of Medical Science, Division of Nuclear Medicine, University of Torino, 10126 Torino, Italy;
| | - Riccardo Laudicella
- Department of Biomedical and Dental Sciences and of Morpho-Functional Imaging, Nuclear Medicine Unit, University of Messina, 98125 Messina, Italy; (R.L.); (S.B.)
- Department of Nuclear Medicine, University Hospital Zurich, University of Zurich, 8006 Zurich, Switzerland; (M.W.H.); (I.A.B.)
| | - Martina Capozza
- Molecular & Preclinical Imaging Centers, Department of Molecular Biotechnology and Health Sciences, University of Torino, Via Nizza 52, 10126 Torino, Italy; (M.C.); (E.T.)
| | - Martin W. Huellner
- Department of Nuclear Medicine, University Hospital Zurich, University of Zurich, 8006 Zurich, Switzerland; (M.W.H.); (I.A.B.)
| | - Irene A. Burger
- Department of Nuclear Medicine, University Hospital Zurich, University of Zurich, 8006 Zurich, Switzerland; (M.W.H.); (I.A.B.)
- Department of Nuclear Medicine, Kantonsspital Baden, 5004 Baden, Switzerland
| | - Sergio Baldari
- Department of Biomedical and Dental Sciences and of Morpho-Functional Imaging, Nuclear Medicine Unit, University of Messina, 98125 Messina, Italy; (R.L.); (S.B.)
| | - Enzo Terreno
- Molecular & Preclinical Imaging Centers, Department of Molecular Biotechnology and Health Sciences, University of Torino, Via Nizza 52, 10126 Torino, Italy; (M.C.); (E.T.)
| | - Désirée Deandreis
- Department of Medical Science, Division of Nuclear Medicine, University of Torino, 10126 Torino, Italy;
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23
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Nimmagadda S. Quantifying PD-L1 Expression to Monitor Immune Checkpoint Therapy: Opportunities and Challenges. Cancers (Basel) 2020; 12:cancers12113173. [PMID: 33137949 PMCID: PMC7692040 DOI: 10.3390/cancers12113173] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 10/19/2020] [Indexed: 12/11/2022] Open
Abstract
Simple Summary Malignant cells hijack the regulatory roles of immune checkpoint proteins for immune evasion and survival. Therapeutics blocking those proteins can restore the balance of the immune system and lead to durable responses in cancer patients. Although a subset of patients derive benefit, there are few non-invasive technologies to guide and monitor those therapies to improve success rates. This is a review of the advancements in non-invasive methods for quantification of immune checkpoint protein programmed death ligand 1 expression, a biomarker detected by immunohistochemistry and widely used for guiding immune checkpoint therapy. Abstract Therapeutics targeting programmed death ligand 1 (PD-L1) protein and its receptor PD-1 are now dominant players in restoring anti-tumor immune responses. PD-L1 detection by immunohistochemistry (IHC) is emerging as a reproducible biomarker for guiding patient stratification for those therapies in some cancers. However, PD-L1 expression in the tumor microenvironment is highly complex. It is upregulated by aberrant genetic alterations, and is highly regulated at the transcriptional, posttranscriptional, and protein levels. Thus, PD-L1 IHC is inadequate to fully understand the relevance of PD-L1 levels in the whole body and their dynamics to improve therapeutic outcomes. Imaging technologies could potentially assist in meeting that need. Early clinical investigations show promising results in quantifying PD-L1 expression in the whole body by positron emission tomography (PET). Within this context, this review summarizes advancements in regulation of PD-L1 expression and imaging agents, and in PD-L1 PET for drug development, and discusses opportunities and challenges presented by these innovations for guiding immune checkpoint therapy (ICT).
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Affiliation(s)
- Sridhar Nimmagadda
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; ; Tel.: +1-410-502-6244; Fax: +1-410-614-3147
- Division of Clinical Pharmacology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
- Department of Pharmacology and Molecular Science, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Bloomberg–Kimmel Institute for Cancer Immunotherapy, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
- The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
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