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Tsuchikama K, Anami Y, Ha SYY, Yamazaki CM. Exploring the next generation of antibody-drug conjugates. Nat Rev Clin Oncol 2024; 21:203-223. [PMID: 38191923 DOI: 10.1038/s41571-023-00850-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/12/2023] [Indexed: 01/10/2024]
Abstract
Antibody-drug conjugates (ADCs) are a promising cancer treatment modality that enables the selective delivery of highly cytotoxic payloads to tumours. However, realizing the full potential of this platform necessitates innovative molecular designs to tackle several clinical challenges such as drug resistance, tumour heterogeneity and treatment-related adverse effects. Several emerging ADC formats exist, including bispecific ADCs, conditionally active ADCs (also known as probody-drug conjugates), immune-stimulating ADCs, protein-degrader ADCs and dual-drug ADCs, and each offers unique capabilities for tackling these various challenges. For example, probody-drug conjugates can enhance tumour specificity, whereas bispecific ADCs and dual-drug ADCs can address resistance and heterogeneity with enhanced activity. The incorporation of immune-stimulating and protein-degrader ADCs, which have distinct mechanisms of action, into existing treatment strategies could enable multimodal cancer treatment. Despite the promising outlook, the importance of patient stratification and biomarker identification cannot be overstated for these emerging ADCs, as these factors are crucial to identify patients who are most likely to derive benefit. As we continue to deepen our understanding of tumour biology and refine ADC design, we will edge closer to developing truly effective and safe ADCs for patients with treatment-refractory cancers. In this Review, we highlight advances in each ADC component (the monoclonal antibody, payload, linker and conjugation chemistry) and provide more-detailed discussions on selected examples of emerging novel ADCs of each format, enabled by engineering of one or more of these components.
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Affiliation(s)
- Kyoji Tsuchikama
- Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, TX, USA.
| | - Yasuaki Anami
- Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Summer Y Y Ha
- Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Chisato M Yamazaki
- Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, TX, USA
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2
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Feng Y, Lee J, Yang L, Hilton MB, Morris K, Seaman S, Edupuganti VVSR, Hsu KS, Dower C, Yu G, So D, Bajgain P, Zhu Z, Dimitrov DS, Patel NL, Robinson CM, Difilippantonio S, Dyba M, Corbel A, Basuli F, Swenson RE, Kalen JD, Suthe SR, Hussain M, Italia JS, Souders CA, Gao L, Schnermann MJ, St Croix B. Engineering CD276/B7-H3-targeted antibody-drug conjugates with enhanced cancer-eradicating capability. Cell Rep 2023; 42:113503. [PMID: 38019654 PMCID: PMC10872261 DOI: 10.1016/j.celrep.2023.113503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Revised: 08/18/2023] [Accepted: 11/13/2023] [Indexed: 12/01/2023] Open
Abstract
CD276/B7-H3 represents a promising target for cancer therapy based on widespread overexpression in both cancer cells and tumor-associated stroma. In previous preclinical studies, CD276 antibody-drug conjugates (ADCs) exploiting a talirine-type pyrrolobenzodiazepine (PBD) payload showed potent activity against various solid tumors but with a narrow therapeutic index and dosing regimen higher than that tolerated in clinical trials using other antibody-talirine conjugates. Here, we describe the development of a modified talirine PBD-based fully human CD276 ADC, called m276-SL-PBD, that is cross-species (human/mouse) reactive and can eradicate large 500-1,000-mm3 triple-negative breast cancer xenografts at doses 10- to 40-fold lower than the maximum tolerated dose. By combining CD276 targeting with judicious genetic and chemical ADC engineering, improved ADC purification, and payload sensitivity screening, these studies demonstrate that the therapeutic index of ADCs can be substantially increased, providing an advanced ADC development platform for potent and selective targeting of multiple solid tumor types.
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Affiliation(s)
- Yang Feng
- Tumor Angiogenesis Unit, Mouse Cancer Genetics Program (MCGP), Center for Cancer Research (CCR), National Cancer Institute (NCI), National Institutes of Health (NIH), Frederick, MD 21702, USA
| | - Jaewon Lee
- Tumor Angiogenesis Unit, Mouse Cancer Genetics Program (MCGP), Center for Cancer Research (CCR), National Cancer Institute (NCI), National Institutes of Health (NIH), Frederick, MD 21702, USA
| | - Liping Yang
- Tumor Angiogenesis Unit, Mouse Cancer Genetics Program (MCGP), Center for Cancer Research (CCR), National Cancer Institute (NCI), National Institutes of Health (NIH), Frederick, MD 21702, USA
| | - Mary Beth Hilton
- Tumor Angiogenesis Unit, Mouse Cancer Genetics Program (MCGP), Center for Cancer Research (CCR), National Cancer Institute (NCI), National Institutes of Health (NIH), Frederick, MD 21702, USA; Basic Research Program, Frederick National Laboratory for Cancer Research (FNLCR), Leidos Biomedical Research, Inc., Frederick, MD 21702, USA
| | - Karen Morris
- Tumor Angiogenesis Unit, Mouse Cancer Genetics Program (MCGP), Center for Cancer Research (CCR), National Cancer Institute (NCI), National Institutes of Health (NIH), Frederick, MD 21702, USA; Basic Research Program, Frederick National Laboratory for Cancer Research (FNLCR), Leidos Biomedical Research, Inc., Frederick, MD 21702, USA
| | - Steven Seaman
- Tumor Angiogenesis Unit, Mouse Cancer Genetics Program (MCGP), Center for Cancer Research (CCR), National Cancer Institute (NCI), National Institutes of Health (NIH), Frederick, MD 21702, USA
| | | | - Kuo-Sheng Hsu
- Tumor Angiogenesis Unit, Mouse Cancer Genetics Program (MCGP), Center for Cancer Research (CCR), National Cancer Institute (NCI), National Institutes of Health (NIH), Frederick, MD 21702, USA
| | - Christopher Dower
- Tumor Angiogenesis Unit, Mouse Cancer Genetics Program (MCGP), Center for Cancer Research (CCR), National Cancer Institute (NCI), National Institutes of Health (NIH), Frederick, MD 21702, USA
| | - Guojun Yu
- Tumor Angiogenesis Unit, Mouse Cancer Genetics Program (MCGP), Center for Cancer Research (CCR), National Cancer Institute (NCI), National Institutes of Health (NIH), Frederick, MD 21702, USA
| | - Daeho So
- Tumor Angiogenesis Unit, Mouse Cancer Genetics Program (MCGP), Center for Cancer Research (CCR), National Cancer Institute (NCI), National Institutes of Health (NIH), Frederick, MD 21702, USA
| | - Pradip Bajgain
- Tumor Angiogenesis Unit, Mouse Cancer Genetics Program (MCGP), Center for Cancer Research (CCR), National Cancer Institute (NCI), National Institutes of Health (NIH), Frederick, MD 21702, USA
| | - Zhongyu Zhu
- Protein Interactions Section, Cancer and Inflammation Program, NCI, NIH, Frederick, MD 21702, USA
| | - Dimiter S Dimitrov
- Protein Interactions Section, Cancer and Inflammation Program, NCI, NIH, Frederick, MD 21702, USA
| | - Nimit L Patel
- Small Animal Imaging Program, FNLCR, Leidos Biomedical Research, Inc., Frederick, MD 21702, USA
| | - Christina M Robinson
- Animal Research Technical Support, FNLCR, Leidos Biomedical Research, Inc., Frederick, MD 21702, USA
| | - Simone Difilippantonio
- Animal Research Technical Support, FNLCR, Leidos Biomedical Research, Inc., Frederick, MD 21702, USA
| | - Marzena Dyba
- Biophysics Resource in the Center for Structural Biology, NCI, NIH, Frederick, MD, USA
| | - Amanda Corbel
- Invention Development Program, Technology Transfer Center, NCI, Frederick, MD 21701, USA
| | - Falguni Basuli
- Chemistry and Synthesis Center, National Heart, Lung, and Blood Institute, NIH, Rockville, MD 20850, USA
| | - Rolf E Swenson
- Chemistry and Synthesis Center, National Heart, Lung, and Blood Institute, NIH, Rockville, MD 20850, USA
| | - Joseph D Kalen
- Small Animal Imaging Program, FNLCR, Leidos Biomedical Research, Inc., Frederick, MD 21702, USA
| | | | | | | | | | - Ling Gao
- Veterans Affairs Long Beach Healthcare System, Long Beach, CA 90822, USA
| | - Martin J Schnermann
- Organic Synthesis Section, Chemical Biology Laboratory, CCR, NCI, Frederick, MD 21702, USA
| | - Brad St Croix
- Tumor Angiogenesis Unit, Mouse Cancer Genetics Program (MCGP), Center for Cancer Research (CCR), National Cancer Institute (NCI), National Institutes of Health (NIH), Frederick, MD 21702, USA.
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3
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Rakotoarinoro N, Dyck YFK, Krebs SK, Assi MK, Parr MK, Stech M. A disruptive clickable antibody design for the generation of antibody-drug conjugates. Antib Ther 2023; 6:298-310. [PMID: 38107665 PMCID: PMC10720948 DOI: 10.1093/abt/tbad023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 10/05/2023] [Accepted: 10/14/2023] [Indexed: 12/19/2023] Open
Abstract
Background Antibody-drug conjugates are cancer therapeutics that combine specificity and toxicity. A highly cytotoxic drug is covalently attached to an antibody that directs it to cancer cells. The conjugation of the drug-linker to the antibody is a key point in research and development as well as in industrial production. The consensus is to conjugate the drug to a surface-exposed part of the antibody to ensure maximum conjugation efficiency. However, the hydrophobic nature of the majority of drugs used in antibody-drug conjugates leads to an increased hydrophobicity of the generated antibody-drug conjugates, resulting in higher liver clearance and decreased stability. Methods In contrast, we describe a non-conventional approach in which the drug is conjugated in a buried part of the antibody. To achieve this, a ready-to-click antibody design was created in which an azido-based non-canonical amino acid is introduced within the Fab cavity during antibody synthesis using nonsense suppression technology. The Fab cavity was preferred over the Fc cavity to circumvent issues related to cleavage of the IgG1 lower hinge region in the tumor microenvironment. Results This antibody design significantly increased the hydrophilicity of the generated antibody-drug conjugates compared to the current best-in-class designs based on non-canonical amino acids, while conjugation efficiency and functionality were maintained. The robustness of this native shielding effect and the versatility of this approach were also investigated. Conclusions This pioneer design may become a starting point for the improvement of antibody-drug conjugates and an option to consider for protecting drugs and linkers from unspecific interactions.
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Affiliation(s)
- Nathanaël Rakotoarinoro
- Institute for Cell Therapy and Immunology branch Bioanalytics and Bioprocesses, Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V., 14476 Potsdam-Golm, Germany
- Institute of Pharmacy, Freie Universität Berlin, 14195 Berlin, Germany
| | - Yan F K Dyck
- Institute of Pharmacy, Freie Universität Berlin, 14195 Berlin, Germany
| | - Simon K Krebs
- Institute for Cell Therapy and Immunology branch Bioanalytics and Bioprocesses, Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V., 14476 Potsdam-Golm, Germany
- Institute of Biotechnology, Technische Universität Berlin, 13355 Berlin, Germany
| | - Miriam-Kousso Assi
- Institute for Cell Therapy and Immunology branch Bioanalytics and Bioprocesses, Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V., 14476 Potsdam-Golm, Germany
- Department of Biotechnology, Hamburg University of Applied Sciences, 21033 Hamburg, Germany
| | - Maria K Parr
- Institute of Pharmacy, Freie Universität Berlin, 14195 Berlin, Germany
| | - Marlitt Stech
- Institute for Cell Therapy and Immunology branch Bioanalytics and Bioprocesses, Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V., 14476 Potsdam-Golm, Germany
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4
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Hejmady S, Pradhan R, Kumari S, Pandey M, Dubey SK, Taliyan R. Pharmacokinetics and toxicity considerations for antibody-drug conjugates: an overview. Bioanalysis 2023; 15:1193-1202. [PMID: 37724472 DOI: 10.4155/bio-2023-0104] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/20/2023] Open
Abstract
Antibody-drug conjugates (ADCs) is one of the fastest-growing drug-delivery systems. It involves a monoclonal antibody conjugated with payload via a ligand that directly targets the expressive protein of diseased cell. Hence, it reduces systemic exposure and provides site-specific delivery along with reduced toxicity. Because of this advantage, researchers have gained interest in this novel system. ADCs have displayed great promise in drug delivery and biomedical applications. However, a lack of understanding exists on their mechanisms of biodistribution, metabolism and side effects. To gain a better understanding of the therapeutics, careful consideration of the pharmacokinetics and toxicity needs to be undertaken. In this review, different pharmacokinetics parameters including distribution, bioanalysis and heterogeneity are discussed for developing novel therapeutics.
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Affiliation(s)
- Siddhanth Hejmady
- Department of Pharmaceutical Sciences & Experimental Therapeutics, College of Pharmacy, University of Iowa, Iowa City, IA 52242, USA
| | - Rajesh Pradhan
- Department of Pharmacy, Birla Institute of Technology & Science, Pilani, Pilani Campus, Rajasthan, 333031, India
| | - Shobha Kumari
- Department of Pharmacy, Birla Institute of Technology & Science, Pilani, Pilani Campus, Rajasthan, 333031, India
| | - Meghna Pandey
- Department of Pharmacy, Birla Institute of Technology & Science, Pilani, Pilani Campus, Rajasthan, 333031, India
| | - Sunil K Dubey
- Department of Pharmacy, Birla Institute of Technology & Science, Pilani, Pilani Campus, Rajasthan, 333031, India
- Medical Research, R&D Healthcare Division, Emami Ltd, Kolkata 700056, India
| | - Rajeev Taliyan
- Department of Pharmacy, Birla Institute of Technology & Science, Pilani, Pilani Campus, Rajasthan, 333031, India
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5
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Carpentier N, Urbani L, Dubruel P, Van Vlierberghe S. The native liver as inspiration to create superior in vitro hepatic models. Biomater Sci 2023; 11:1091-1115. [PMID: 36594602 DOI: 10.1039/d2bm01646j] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Drug induced liver injury (DILI) is one of the major reasons of drug withdrawal during the different phases of drug development. The later in the drug development a drug is discovered to be toxic, the higher the economical as well as the ethical impact will be. In vitro models for early detection of drug liver toxicity are under constant development, however to date a superior model of the liver is still lacking. Ideally, a highly reliable model should be established to maintain the different hepatic cell functionalities to the greatest extent possible, during a period of time long enough to allow for tracking of the toxicity of compounds. In the case of DILI, toxicity can appear even after months of exposure. To reach this goal, an in vitro model should be developed that mimics the in vivo liver environment, function and response to external stimuli. The different approaches for the development of liver models currently used in the field of tissue engineering will be described in this review. Combining different technologies, leading to optimal materials, cells and 3D-constructs will ultimately lead to an ideal superior model that fully recapitulates the liver.
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Affiliation(s)
- Nathan Carpentier
- Polymer Chemistry & Biomaterials Group, Centre of Macromolecular Chemistry, Ghent University, Ghent, Belgium.
| | - Luca Urbani
- The Roger Williams Institute of Hepatology, Foundation for Liver Research, London SE5 9NT, UK.,Faculty of Life Sciences and Medicine, King's College London, London, UK
| | - Peter Dubruel
- Polymer Chemistry & Biomaterials Group, Centre of Macromolecular Chemistry, Ghent University, Ghent, Belgium.
| | - Sandra Van Vlierberghe
- Polymer Chemistry & Biomaterials Group, Centre of Macromolecular Chemistry, Ghent University, Ghent, Belgium.
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6
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Beaumont K, Pike A, Davies M, Savoca A, Vasalou C, Harlfinger S, Ramsden D, Ferguson D, Hariparsad N, Jones O, McGinnity D. ADME and DMPK considerations for the discovery and development of antibody drug conjugates (ADCs). Xenobiotica 2022; 52:770-785. [PMID: 36314242 DOI: 10.1080/00498254.2022.2141667] [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: 11/06/2022]
Abstract
The therapeutic concept of antibody drug conjugates (ADCs) is to selectively target tumour cells with small molecule cytotoxic drugs to maximise cell kill benefit and minimise healthy tissue toxicity.An ADC generally consists of an antibody that targets a protein on the surface of tumour cells chemically linked to a warhead small molecule cytotoxic drug.To deliver the warhead to the tumour cell, the antibody must bind to the target protein and in general be internalised into the cell. Following internalisation, the cytotoxic agent can be released in the endosomal or lysosomal compartment (via different mechanisms). Diffusion or transport out of the endosome or lysosome allows the cytotoxic drug to express its cell-killing pharmacology. Alternatively, some ADCs (e.g. EDB-ADCs) rely on extracellular cleavage releasing membrane permeable warheads.One potentially important aspect of the ADC mechanism is the 'bystander effect' whereby the cytotoxic drug released in the targeted cell can diffuse out of that cell and into other (non-target expressing) tumour cells to exert its cytotoxic effect. This is important as solid tumours tend to be heterogeneous and not all cells in a tumour will express the targeted protein.The combination of large and small molecule aspects in an ADC poses significant challenges to the disposition scientist in describing the ADME properties of the entire molecule.This article will review the ADC landscape and the ADME properties of successful ADCs, with the aim of outlining best practice and providing a perspective of how the field can further facilitate the discovery and development of these important therapeutic modalities.
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Affiliation(s)
- Kevin Beaumont
- Drug Metabolism and Pharmacokinetics, Early Oncology Research and Development, Cambridge, UK
| | - Andy Pike
- Drug Metabolism and Pharmacokinetics, Early Oncology Research and Development, Cambridge, UK
| | - Michael Davies
- Drug Metabolism and Pharmacokinetics, Early Oncology Research and Development, Cambridge, UK
| | - Adriana Savoca
- Drug Metabolism and Pharmacokinetics, Early Oncology Research and Development, Cambridge, UK
| | - Christina Vasalou
- Drug Metabolism and Pharmacokinetics, Early Oncology Research and Development, AstraZeneca, Boston, MA, USA
| | - Steffi Harlfinger
- Drug Metabolism and Pharmacokinetics, Early Oncology Research and Development, Cambridge, UK
| | - Diane Ramsden
- Drug Metabolism and Pharmacokinetics, Early Oncology Research and Development, AstraZeneca, Boston, MA, USA
| | - Douglas Ferguson
- Drug Metabolism and Pharmacokinetics, Early Oncology Research and Development, AstraZeneca, Boston, MA, USA
| | - Niresh Hariparsad
- Drug Metabolism and Pharmacokinetics, Early Oncology Research and Development, AstraZeneca, Boston, MA, USA
| | - Owen Jones
- Drug Metabolism and Pharmacokinetics, Early Oncology Research and Development, Cambridge, UK
| | - Dermot McGinnity
- Drug Metabolism and Pharmacokinetics, Early Oncology Research and Development, Cambridge, UK
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7
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Matikonda SS, McLaughlin R, Shrestha P, Lipshultz C, Schnermann MJ. Structure-Activity Relationships of Antibody-Drug Conjugates: A Systematic Review of Chemistry on the Trastuzumab Scaffold. Bioconjug Chem 2022; 33:1241-1253. [PMID: 35801843 DOI: 10.1021/acs.bioconjchem.2c00177] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Antibody-drug conjugates (ADCs) are a rapidly growing class of cancer therapeutics that seek to overcome the low therapeutic index of conventional cytotoxic agents. However, realizing this goal has been a significant challenge. ADCs comprise several independently modifiable components, including the antibody, payload, linker, and bioconjugation method. Many approaches have been developed to improve the physical properties, potency, and selectivity of ADCs. The anti-HER-2 antibody trastuzumab, first approved in 1998, has emerged as an exceptional targeting agent for ADCs, as well as a broadly used platform for testing new technologies. The extensive work in this area enables the comparison of various linker strategies, payloads, drug-to-antibody ratios (DAR), and mode of attachment. In this review, these conjugates, ranging from the first clinically approved trastuzumab ADC, ado-trastuzumab emtansine (Kadcyla), to the latest variants are described with the goal of providing a broad overview, as well as enabling the comparison of existing and emerging conjugate technologies.
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Affiliation(s)
- Siddharth S Matikonda
- Chemical Biology Laboratory, NIH/NCI/CCR, 376 Boyles Street, Frederick, Maryland 21702, United States
| | - Ryan McLaughlin
- Chemical Biology Laboratory, NIH/NCI/CCR, 376 Boyles Street, Frederick, Maryland 21702, United States
| | - Pradeep Shrestha
- Chemical Biology Laboratory, NIH/NCI/CCR, 376 Boyles Street, Frederick, Maryland 21702, United States
| | - Carol Lipshultz
- Chemical Biology Laboratory, NIH/NCI/CCR, 376 Boyles Street, Frederick, Maryland 21702, United States
| | - Martin J Schnermann
- Chemical Biology Laboratory, NIH/NCI/CCR, 376 Boyles Street, Frederick, Maryland 21702, United States
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8
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Thapaliya ER, Usama SM, Patel NL, Feng Y, Kalen JD, St Croix B, Schnermann MJ. Cyanine Masking: A Strategy to Test Functional Group Effects on Antibody Conjugate Targeting. Bioconjug Chem 2022; 33:718-725. [PMID: 35389618 PMCID: PMC10506421 DOI: 10.1021/acs.bioconjchem.2c00083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Conjugates of small molecules and antibodies are broadly employed diagnostic and therapeutic agents. Appending a small molecule to an antibody often significantly impacts the properties of the resulting conjugate. Here, we detail a systematic study investigating the effect of various functional groups on the properties of antibody-fluorophore conjugates. This was done through the preparation and analysis of a series of masked heptamethine cyanines (CyMasks)-bearing amides with varied functional groups. These were designed to exhibit a broad range of physical properties, and include hydrophobic (-NMe2), pegylated (NH-PEG-8 or NH-PEG-24), cationic (NH-(CH2)2NMe3+), anionic (NH-(CH2)2SO3-), and zwitterionic (N-(CH2)2NMe3+)-(CH2)3SO3-) variants. The CyMask series was appended to monoclonal antibodies (mAbs) and analyzed for the effects on tumor targeting, clearance, and non-specific organ uptake. Among the series, zwitterionic and pegylated dye conjugates had the highest tumor-to-background ratio (TBR) and a low liver-to-background ratio. By contrast, the cationic and zwitterionic probes had high tumor signal and high TBR, although the latter also exhibited an elevated liver-to-background ratio (LBR). Overall, these studies provide a strategy to test the functional group effects and suggest that zwitterionic substituents possess an optimal combination of high tumor signal, TBR, and low LBR. These results suggest an appealing strategy to mask hydrophobic payloads, with the potential to improve the properties of bioconjugates in vivo.
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Affiliation(s)
- Ek Raj Thapaliya
- Chemical Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702, United States
| | - Syed Muhammad Usama
- Chemical Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702, United States
| | - Nimit L Patel
- Small Animal Imaging Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research Inc., Frederick, Maryland 21702, United States
| | - Yang Feng
- Tumor Angiogenesis Unit, Mouse Cancer Genetics Program (MCGP), National Cancer Institute, NIH, Frederick, Maryland 21702, United States
| | - Joseph D Kalen
- Small Animal Imaging Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research Inc., Frederick, Maryland 21702, United States
| | - Brad St Croix
- Tumor Angiogenesis Unit, Mouse Cancer Genetics Program (MCGP), National Cancer Institute, NIH, Frederick, Maryland 21702, United States
| | - Martin J Schnermann
- Chemical Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702, United States
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9
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Lu JQ, Wong KB, Shaw PC. A Sixty-Year Research and Development of Trichosanthin, a Ribosome-Inactivating Protein. Toxins (Basel) 2022; 14:toxins14030178. [PMID: 35324675 PMCID: PMC8950148 DOI: 10.3390/toxins14030178] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 02/23/2022] [Accepted: 02/25/2022] [Indexed: 02/04/2023] Open
Abstract
Tian Hua Fen, a herbal powder extract that contains trichosanthin (TCS), was used as an abortifacient in traditional Chinese medicine. In 1972, TCS was purified to alleviate the side effects. Because of its clinical applications, TCS became one of the most active research areas in the 1960s to the 1980s in China. These include obtaining the sequence information in the 1980s and the crystal structure in 1995. The replication block of TCS on human immunodeficiency virus in lymphocytes and macrophages was found in 1989 and started a new chapter of its development. Clinical studies were subsequently conducted. TCS was also found to have the potential for gastric and colorectal cancer treatment. Studies on its mechanism showed TCS acts as an rRNA N-glycosylase (EC 3.2.2.22) by hydrolyzing and depurinating A-4324 in α-sarcin/ricin loop on 28S rRNA of rat ribosome. Its interaction with acidic ribosomal stalk proteins was revealed in 2007, and its trafficking in mammalian cells was elucidated in the 2000s. The adverse drug reactions, such as inducing immune responses, short plasma half-life, and non-specificity, somehow became the obstacles to its usage. Immunotoxins, sequence modification, or coupling with polyethylene glycerol and dextran were developed to improve the pharmacological properties. TCS has nicely shown the scientific basis of traditional Chinese medicine and how its research and development have expanded the knowledge and applications of ribosome-inactivating proteins.
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Affiliation(s)
- Jia-Qi Lu
- Centre for Protein Science and Crystallography, School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China; (J.-Q.L.); (K.-B.W.)
| | - Kam-Bo Wong
- Centre for Protein Science and Crystallography, School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China; (J.-Q.L.); (K.-B.W.)
| | - Pang-Chui Shaw
- Centre for Protein Science and Crystallography, School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China; (J.-Q.L.); (K.-B.W.)
- Li Dak Sum Yip Yio Chin R&D Centre for Chinese Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, China
- Correspondence:
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10
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Chang HP, Li Z, Shah DK. Development of a Physiologically-Based Pharmacokinetic Model for Whole-Body Disposition of MMAE Containing Antibody-Drug Conjugate in Mice. Pharm Res 2022; 39:1-24. [PMID: 35044590 DOI: 10.1007/s11095-021-03162-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Accepted: 12/21/2021] [Indexed: 12/13/2022]
Abstract
PURPOSE To quantitate and mathematically characterize the whole-body pharmacokinetics (PK) of different ADC analytes following administration of an MMAE-conjugated ADC in tumor-bearing mice. METHODS The PK of different ADC analytes (total antibody, total drug, unconjugated drug) was measured following administration of an MMAE-conjugated ADC in tumor-bearing mice. The PK of ADC analytes was compared with the whole-body PK of the antibody and drug obtained following administration of these molecules alone. An ADC PBPK model was developed by linking antibody PBPK model with small-molecule PBPK model, where the drug was assumed to deconjugate in DAR-dependent manner. RESULTS Comparison of antibody biodistribution coefficient (ABC) values for total antibody suggests that conjugation of drug did not significantly affect the PK of antibody. Comparison of tissue:plasma AUC ratio (T/P) for the conjugated drug and total antibody suggests that in certain tissues (e.g., spleen) ADC may demonstrate higher deconjugation. It was observed that the tissue distribution profile of the drug can be altered following its conjugation to antibody. For example, MMAE distribution to the liver was found to increase while its distribution to the heart was found to decrease upon conjugation to antibody. MMAE exposure in the tumor was found to increase by ~20-fold following administration as conjugate (i.e., ADC). The PBPK model was able to a priori predict the PK of all three ADC analytes in plasma, tissues, and tumor reasonably well. CONCLUSIONS The ADC PBPK model developed here serves as a platform for translational and clinical investigations of MMAE containing ADCs.
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Affiliation(s)
- Hsuan-Ping Chang
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, The State University of New York at Buffalo, 455 Pharmacy Building, Buffalo, New York, 14214-8033, USA
| | - Zhe Li
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, The State University of New York at Buffalo, 455 Pharmacy Building, Buffalo, New York, 14214-8033, USA
| | - Dhaval K Shah
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, The State University of New York at Buffalo, 455 Pharmacy Building, Buffalo, New York, 14214-8033, USA.
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11
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Giese M, Davis PD, Woodman RH, Hermanson G, Pokora A, Vermillion M. Linker Architectures as Steric Auxiliaries for Altering Enzyme-Mediated Payload Release from Bioconjugates. Bioconjug Chem 2021; 32:2257-2267. [PMID: 34587447 DOI: 10.1021/acs.bioconjchem.1c00429] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Protease-activated prodrugs leverage the increased activity of proteases in the tumor microenvironment and the tight regulation in healthy tissues to provide selective activation of cytotoxins in the tumor while minimizing toxicity to normal tissues. One of the largest classes of protease-activated prodrugs are composed of therapeutic agents conjugated to macromolecular carriers via peptide motifs that are substrates for cathepsin B, and antibody-drug conjugates are one of the most successful designs within this class. However, many of these peptide motifs are also cleaved by extracellular enzymes such as elastase and carboxylesterase 1C. Additionally, some peptide sequences have little selectivity for other lysosomal cathepsins, which have also been found to have extracellular activity in normal physiological processes. A lack of selectivity or oversensitivity to other extracellular enzymes can lead to off-target release of the cytotoxic payload and subsequent toxicities. In this report, we describe an approach for modulating cathepsin-mediated release of the cytotoxic payload through steric shielding provided by the synergistic effects of appropriately designed hydrophilic linkers and the conjugated carrier. We prepared a fluorogenic model payload with a Val-Cit cleavable trigger and attached the trigger-payload to a variety of PEG-based linker architectures with different numbers of PEG arms (y), different numbers of ethylene oxide units in each arm (n), and different distances between the cleavable trigger and PEG branch point (D'). These linker-payloads were then used to prepare DAR2 conjugates with the cleavable triggers at three different distances (D) from the antibody, and cathepsin-mediated payload release was monitored with in vitro assays. The results show that structural variables of the linker architectures can be manipulated to effectively shield enzymatically labile trigger-payloads from enzymes with readily accessible binding sites, and may offer an additional strategy for balancing off-target and tumor-targeted payload release.
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Affiliation(s)
- Matthew Giese
- Quanta BioDesign, 7470 Montgomery Drive, Plain City, Ohio 43064, United States
| | - Paul D Davis
- Quanta BioDesign, 7470 Montgomery Drive, Plain City, Ohio 43064, United States
| | - Robert H Woodman
- Quanta BioDesign, 7470 Montgomery Drive, Plain City, Ohio 43064, United States
| | - Greg Hermanson
- Quanta BioDesign, 7470 Montgomery Drive, Plain City, Ohio 43064, United States
| | - Alex Pokora
- Quanta BioDesign, 7470 Montgomery Drive, Plain City, Ohio 43064, United States
| | - Melissa Vermillion
- Quanta BioDesign, 7470 Montgomery Drive, Plain City, Ohio 43064, United States
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12
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Kaempffe A, Dickgiesser S, Rasche N, Paoletti A, Bertotti E, De Salve I, Sirtori FR, Kellner R, Könning D, Hecht S, Anderl J, Kolmar H, Schröter C. Effect of Conjugation Site and Technique on the Stability and Pharmacokinetics of Antibody-Drug Conjugates. J Pharm Sci 2021; 110:3776-3785. [PMID: 34363839 DOI: 10.1016/j.xphs.2021.08.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 08/02/2021] [Accepted: 08/02/2021] [Indexed: 11/18/2022]
Abstract
Appropriate selection of conjugation sites and conjugation technologies is now widely accepted as crucial for the success of antibody-drug conjugates (ADCs). Herein, we present ADCs conjugated by different conjugation methods to different conjugation positions being systematically characterized by multiple in vitro assays as well as in vivo pharmacokinetic (PK) analyses in transgenic Tg276 mice. Conjugation to cysteines, genetically introduced at positions N325, L328, S239, D265, and S442, was compared to enzymatic conjugation via microbial transglutaminase (mTG) either to C-terminal light (LC) or heavy chain (HC) recognition motifs or to endogenous position Q295 of a native antibody. All conjugations yielded homogeneous DAR 2 ADCs with similar hydrophobicity, thermal stability, human neonatal Fc receptor (huFcRn) binding, and serum stability properties, but with pronounced differences in their PK profiles. mTG-conjugated ADC variants conjugated either to Q295 or to LC recognition motifs showed superior PK behavior. Within the panel of engineered cysteine variants L328 showed a similar PK profile compared to previously described S239 but superior PK compared to S442, D265, and N325. While all positions were first tested with trastuzumab, L328 and mTG LC were further evaluated with additional antibody scaffolds derived from clinically evaluated monoclonal antibodies (mAb). Based on PK analyses, this study confirms the newly described position L328 as favorable site for cysteine conjugation, comparable to the well-established engineered cysteine position S239, and emphasizes the favorable position Q295 of native antibodies and the tagged LC antibody variant for enzymatic conjugations via mTG. In addition, hemizygous Tg276 mice are evaluated as an adequate model for ADC pharmacokinetics, facilitating the selection of suitable ADC candidates early in the drug discovery process.
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Affiliation(s)
- Anna Kaempffe
- Institute for Organic Chemistry and Biochemistry, Technische Universität Darmstadt, Alarich-Weiss-Straße 4, 64287 Darmstadt, Germany; Antibody Drug Conjugates & Targeted NBE Therapeutics, Merck KGaA, Frankfurter Strasse 250, 64293 Darmstadt, Germany
| | - Stephan Dickgiesser
- Antibody Drug Conjugates & Targeted NBE Therapeutics, Merck KGaA, Frankfurter Strasse 250, 64293 Darmstadt, Germany
| | - Nicolas Rasche
- Antibody Drug Conjugates & Targeted NBE Therapeutics, Merck KGaA, Frankfurter Strasse 250, 64293 Darmstadt, Germany
| | - Andrea Paoletti
- NBE-DMPK Discovery and Preclinical Bioanalytics, Merck KGaA, RBM S.p.A., Via Ribes 1, 10010 Colleretto Giacosa (TO), Italy
| | - Elisa Bertotti
- NBE-DMPK Discovery and Preclinical Bioanalytics, Merck KGaA, RBM S.p.A., Via Ribes 1, 10010 Colleretto Giacosa (TO), Italy
| | - Ilse De Salve
- NBE-DMPK Discovery and Preclinical Bioanalytics, Merck KGaA, RBM S.p.A., Via Ribes 1, 10010 Colleretto Giacosa (TO), Italy
| | - Federico Riccardi Sirtori
- NBE-DMPK Discovery and Preclinical Bioanalytics, Merck KGaA, RBM S.p.A., Via Ribes 1, 10010 Colleretto Giacosa (TO), Italy
| | - Roland Kellner
- Antibody Drug Conjugates & Targeted NBE Therapeutics, Merck KGaA, Frankfurter Strasse 250, 64293 Darmstadt, Germany
| | - Doreen Könning
- Antibody Drug Conjugates & Targeted NBE Therapeutics, Merck KGaA, Frankfurter Strasse 250, 64293 Darmstadt, Germany
| | - Stefan Hecht
- Antibody Drug Conjugates & Targeted NBE Therapeutics, Merck KGaA, Frankfurter Strasse 250, 64293 Darmstadt, Germany
| | - Jan Anderl
- Antibody Drug Conjugates & Targeted NBE Therapeutics, Merck KGaA, Frankfurter Strasse 250, 64293 Darmstadt, Germany
| | - Harald Kolmar
- Institute for Organic Chemistry and Biochemistry, Technische Universität Darmstadt, Alarich-Weiss-Straße 4, 64287 Darmstadt, Germany
| | - Christian Schröter
- Antibody Drug Conjugates & Targeted NBE Therapeutics, Merck KGaA, Frankfurter Strasse 250, 64293 Darmstadt, Germany.
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13
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Le PJ, Miersch S, Forbes MW, Jarvik N, Ku A, Sidhu SS, Reilly RM, Winnik MA. Site-Specific Conjugation of Metal-Chelating Polymers to Anti-Frizzled-2 Antibodies via Microbial Transglutaminase. Biomacromolecules 2021; 22:2491-2504. [PMID: 33961407 DOI: 10.1021/acs.biomac.1c00246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Metal-chelating polymer-based radioimmunoconjugates (RICs) are effective agents for radioimmunotherapy but are currently limited by nonspecific binding and off-target organ uptake. Nonspecific binding appears after conjugation of the polymer to the antibody and may be related to random lysine conjugation since the polymers themselves do not bind to cells. To investigate the role of conjugation sites on nonspecific binding of polymer RICs, we developed a microbial transglutaminase reaction to prepare site-specific antibody-polymer conjugates. The reaction was enabled by introducing a Q-tag (i.e., 7M48) into antibody (i.e., Fab) fragments and synthesizing a polyglutamide-based metal-chelating polymer with a PEG amine block to yield substrates. Mass spectrometric analyses confirmed that the microbial transglutaminase conjugation reaction was site-specific. For comparison, random lysine conjugation analogs with an average of one polymer per Fab were prepared by bis-aryl hydrazone conjugation. Conjugates were prepared from an anti-frizzled-2 Fab to target the Wnt pathway, along with a nonbinding specificity control, anti-Luciferase Fab. Fabs were engineered from a trastuzumab-based IgG1 framework and lack lysines in the antigen-binding site. Conjugates were analyzed for thermal conformational stability by differential scanning fluorimetry, which showed that the site-specific conjugate had a similar melting temperature to the parent Fab. Binding assays by biolayer interferometry showed that the site-specific anti-frizzled-2 conjugate maintained high affinity to the antigen, while the random conjugate showed a 10-fold decrease in affinity, which was largely due to changes in association rates. Radioligand cell-binding assays on frizzled-2+ PANC-1 cells and frizzled-2- CHO cells showed that the site-specific anti-frizzled-2 conjugate had ca. 4-fold lower nonspecific binding compared to the random conjugate. Site-specific conjugation appeared to reduce nonspecific binding associated with random conjugation of the polymer in polymer RICs.
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Affiliation(s)
- Penny J Le
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON M5S 1H6, Canada
| | - Shane Miersch
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON M5S 3E1, Canada
| | - Matthew W Forbes
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON M5S 1H6, Canada
| | - Nick Jarvik
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON M5S 3E1, Canada
| | - Anthony Ku
- Department of Pharmaceutical Sciences, University of Toronto, 144 College Street, Toronto, ON M5S 3M2, Canada
| | - Sachdev S Sidhu
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON M5S 3E1, Canada
| | - Raymond M Reilly
- Department of Pharmaceutical Sciences, University of Toronto, 144 College Street, Toronto, ON M5S 3M2, Canada.,Joint Department of Medical Imaging and Princess Margaret Cancer Centre, University Health Network, Toronto, ON M5G 2C4, Canada
| | - Mitchell A Winnik
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON M5S 1H6, Canada.,Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, ON M5S 3E2, Canada
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14
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Exatecan Antibody Drug Conjugates Based on a Hydrophilic Polysarcosine Drug-Linker Platform. Pharmaceuticals (Basel) 2021; 14:ph14030247. [PMID: 33803327 PMCID: PMC8000490 DOI: 10.3390/ph14030247] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Revised: 03/02/2021] [Accepted: 03/06/2021] [Indexed: 12/20/2022] Open
Abstract
We herein report the development and evaluation of a novel HER2-targeting antibody-drug conjugate (ADC) based on the topoisomerase I inhibitor payload exatecan, using our hydrophilic monodisperse polysarcosine (PSAR) drug-linker platform (PSARlink). In vitro and in vivo experiments were conducted in breast and gastric cancer models to characterize this original ADC and gain insight about the drug-linker structure-activity relationship. The inclusion of the PSAR hydrophobicity masking entity efficiently reduced the overall hydrophobicity of the conjugate and yielded an ADC sharing the same pharmacokinetic profile as the unconjugated antibody despite the high drug-load of the camptothecin-derived payload (drug-antibody ratio of 8). Tra-Exa-PSAR10 demonstrated strong anti-tumor activity at 1 mg/kg in an NCI-N87 xenograft model, outperforming the FDA-approved ADC DS-8201a (Enhertu), while being well tolerated in mice at a dose of 100 mg/kg. In vitro experiments showed that this exatecan-based ADC demonstrated higher bystander killing effect than DS-8201a and overcame resistance to T-DM1 (Kadcyla) in preclinical HER2+ breast and esophageal models, suggesting potential activity in heterogeneous and resistant tumors. In summary, the polysarcosine-based hydrophobicity masking approach allowsfor the generation of highly conjugated exatecan-based ADCs having excellent physicochemical properties, an improved pharmacokinetic profile, and potent in vivo anti-tumor activity.
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15
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Not so innocent: Impact of fluorophore chemistry on the in vivo properties of bioconjugates. Curr Opin Chem Biol 2021; 63:38-45. [PMID: 33684856 DOI: 10.1016/j.cbpa.2021.01.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 01/22/2021] [Accepted: 01/28/2021] [Indexed: 12/11/2022]
Abstract
The combination of targeting ligands and fluorescent dyes is a powerful strategy to observe cell types and tissues of interest. Conjugates of peptides, proteins, and, in particular, monoclonal antibodies (mAbs) exhibit excellent tumor targeting in various contexts. This approach has been translated to a clinical setting to provide real-time molecular insights during the surgical resection of solid tumors. A critical element of this approach is the generation of highly fluorescent bioconjugates that maintain the properties of the parent targeting ligand. A number of studies have found that fluorophores can dramatically impact the pharmacokinetic and tumor-targeting properties of the bioconjugates they are meant to only innocently observe. In this review, we summarize several examples of these effects and highlight strategies that have been used to mitigate them. These include the application of site-specific labeling chemistries, modulating label density, and altering the structure of the fluorescent probe itself. In particular, we point out the significant potential of fluorophores with hydrophilic but net-neutral structures. Overall, this review highlights recent progress in refining the in vivo properties of fluorescent bioconjugates, and we hope, will inform future efforts in this area.
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16
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Lyski RD, Bou LB, Lau UY, Meyer DW, Cochran JH, Okeley NM, Emmerton KK, Zapata F, Simmons JK, Trueblood ES, Ortiz DJ, Zaval MC, Snead KM, Jin S, Farr LM, Ryan MC, Senter PD, Jeffrey SC. Development of Novel Antibody-Camptothecin Conjugates. Mol Cancer Ther 2020; 20:329-339. [PMID: 33273058 DOI: 10.1158/1535-7163.mct-20-0526] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 08/14/2020] [Accepted: 11/09/2020] [Indexed: 11/16/2022]
Abstract
We have developed a highly active and well-tolerated camptothecin (CPT) drug-linker designed for antibody-mediated drug delivery in which the lead molecule consists of a 7-aminomethyl-10,11-methylenedioxy CPT (CPT1) derivative payload attached to a novel hydrophilic protease-cleavable valine-lysine-glycine tripeptide linker. A defined polyethylene glycol stretcher was included to improve the properties of the drug-linker, facilitating high antibody-drug conjugate (ADC) drug loading, while reducing the propensity for aggregation. A CPT1 ADC with 8 drug-linkers/mAb displayed a pharmacokinetic profile coincident with parental unconjugated antibody and had high serum stability. The ADCs were broadly active against cancer cells in vitro and in mouse xenograft models, giving tumor regressions and complete responses at low (≤3 mg/kg, single administration) doses. Pronounced activities were obtained in both solid and hematologic tumor models and in models of bystander killing activity and multidrug resistance. Payload release studies demonstrated that two CPTs, CPT1 and the corresponding glycine analog (CPT2), were released from a cAC10 ADC by tumor cells. An ADC containing this drug-linker was well tolerated in rats at 60 mg/kg, given weekly four times. Thus, ADCs comprised of this valine-lysine-glycine linker with CPT drug payloads have promise in targeted drug delivery.
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Affiliation(s)
| | | | - Uland Y Lau
- Neoleukin Therapeutics, Inc., Seattle, Washington
| | | | | | | | | | | | | | | | | | | | | | - Steven Jin
- Seagen Inc., Bothell, Seattle, Washington
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