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Yap SY, Butcher T, Spears RJ, McMahon C, Thanasi IA, Baker JR, Chudasama V. Chemo- and regio-selective differential modification of native cysteines on an antibody via the use of dehydroalanine forming reagents. Chem Sci 2024; 15:8557-8568. [PMID: 38846383 PMCID: PMC11151841 DOI: 10.1039/d4sc00392f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Accepted: 04/29/2024] [Indexed: 06/09/2024] Open
Abstract
Protein modification has garnered increasing interest over the past few decades and has become an important tool in many aspects of chemical biology. In recent years, much effort has focused on site-selective modification strategies that generate more homogenous bioconjugates, and this is particularly so in the antibody modification space. Modifying native antibodies by targeting solvent-accessible cysteines liberated by interchain disulfide reduction is, perhaps, the predominant strategy for achieving more site-selectivity on an antibody scaffold. This is evidenced by numerous approved antibody therapeutics that have utilised cysteine-directed conjugation reagents and the plethora of methods/strategies focused on antibody cysteine modification. However, all of these methods have a common feature in that after the reduction of native solvent-accessible cystines, the liberated cysteines are all reacted in the same manner. Herein, we report the discovery and application of dehydroalanine forming reagents (including novel reagents) capable of regio- and chemo-selectively modifying these cysteines (differentially) on a clinically relevant antibody fragment and a full antibody. We discovered that these reagents could enable differential reactivity between light chain C-terminal cysteines, heavy chain hinge region cysteines (cysteines with an adjacent proline residue, Cys-Pro), and other heavy chain internal cysteines. This differential reactivity was also showcased on small molecules and on the peptide somatostatin. The application of these dehydroalanine forming reagents was exemplified in the preparation of a dually modified antibody fragment and full antibody. Additionally, we discovered that readily available amide coupling agents can be repurposed as dehydroalanine forming reagents, which could be of interest to the broader field of chemical biology.
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Affiliation(s)
- Steven Y Yap
- Department of Chemistry, University College London 20 Gordon Street London WC1H 0AJ UK
| | - Tobias Butcher
- Department of Chemistry, University College London 20 Gordon Street London WC1H 0AJ UK
| | - Richard J Spears
- Department of Chemistry, University College London 20 Gordon Street London WC1H 0AJ UK
| | - Clíona McMahon
- Department of Chemistry, University College London 20 Gordon Street London WC1H 0AJ UK
| | - Ioanna A Thanasi
- Department of Chemistry, University College London 20 Gordon Street London WC1H 0AJ UK
| | - James R Baker
- Department of Chemistry, University College London 20 Gordon Street London WC1H 0AJ UK
| | - Vijay Chudasama
- Department of Chemistry, University College London 20 Gordon Street London WC1H 0AJ UK
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Walsh SJ, Bargh JD, Dannheim FM, Hanby AR, Seki H, Counsell AJ, Ou X, Fowler E, Ashman N, Takada Y, Isidro-Llobet A, Parker JS, Carroll JS, Spring DR. Site-selective modification strategies in antibody-drug conjugates. Chem Soc Rev 2021; 50:1305-1353. [PMID: 33290462 DOI: 10.1039/d0cs00310g] [Citation(s) in RCA: 205] [Impact Index Per Article: 68.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Antibody-drug conjugates (ADCs) harness the highly specific targeting capabilities of an antibody to deliver a cytotoxic payload to specific cell types. They have garnered widespread interest in drug discovery, particularly in oncology, as discrimination between healthy and malignant tissues or cells can be achieved. Nine ADCs have received approval from the US Food and Drug Administration and more than 80 others are currently undergoing clinical investigations for a range of solid tumours and haematological malignancies. Extensive research over the past decade has highlighted the critical nature of the linkage strategy adopted to attach the payload to the antibody. Whilst early generation ADCs were primarily synthesised as heterogeneous mixtures, these were found to have sub-optimal pharmacokinetics, stability, tolerability and/or efficacy. Efforts have now shifted towards generating homogeneous constructs with precise drug loading and predetermined, controlled sites of attachment. Homogeneous ADCs have repeatedly demonstrated superior overall pharmacological profiles compared to their heterogeneous counterparts. A wide range of methods have been developed in the pursuit of homogeneity, comprising chemical or enzymatic methods or a combination thereof to afford precise modification of specific amino acid or sugar residues. In this review, we discuss advances in chemical and enzymatic methods for site-specific antibody modification that result in the generation of homogeneous ADCs.
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Affiliation(s)
- Stephen J Walsh
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.
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Critical Issues in the Development of Immunotoxins for Anticancer Therapy. J Pharm Sci 2019; 109:104-115. [PMID: 31669121 DOI: 10.1016/j.xphs.2019.10.037] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 09/23/2019] [Accepted: 10/21/2019] [Indexed: 12/16/2022]
Abstract
Immunotoxins (ITs) are attractive anticancer modalities aimed at cancer-specific delivery of highly potent cytotoxic protein toxins. An IT consists of a targeting domain (an antibody, cytokine, or another cell-binding protein) chemically conjugated or recombinantly fused to a highly cytotoxic payload (a bacterial and plant toxin or human cytotoxic protein). The mode of action of ITs is killing designated cancer cells through the effector function of toxins in the cytosol after cellular internalization via the targeted cell-specific receptor-mediated endocytosis. Although numerous ITs of diverse structures have been tested in the past decades, only 3 ITs-denileukin diftitox, tagraxofusp, and moxetumomab pasudotox-have been clinically approved for treating hematological cancers. No ITs against solid tumors have been approved for clinical use. In this review, we discuss critical research and development issues associated with ITs that limit their clinical success as well as strategies to overcome these obstacles. The issues include off-target and on-target toxicities, immunogenicity, human cytotoxic proteins, antigen target selection, cytosolic delivery efficacy, solid-tumor targeting, and developability. To realize the therapeutic promise of ITs, novel strategies for safe and effective cytosolic delivery into designated tumors, including solid tumors, are urgently needed.
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Lee BS, Lee Y, Park J, Jeong BS, Jo M, Jung ST, Yoo TH. Construction of an immunotoxin via site-specific conjugation of anti-Her2 IgG and engineered Pseudomonas exotoxin A. J Biol Eng 2019; 13:56. [PMID: 31285754 PMCID: PMC6588878 DOI: 10.1186/s13036-019-0188-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 06/12/2019] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Immunotoxins consisting of a toxin from bacteria or plants and a targeting module have been developed as potent anti-cancer therapeutics. The majority of them, especially those in preclinical or clinical testing stages, are fusion proteins of a toxin and antibody fragment. Immunotoxins based on full-length antibodies are less studied, even though the fragment crystallizable (Fc) domain plays an important role in regulating the concentration of immunoglobulin G (IgG) in the serum and in antibody-mediated immune responses against pathogens. RESULTS We devised a method to site-specifically conjugate IgG and another protein using a cysteine residue introduced into the IgG and a bio-orthogonally reactive unnatural amino acid incorporated into the other protein. The human epidermal growth factor receptor 2 (Her2)-targeting IgG, trastuzumab, was engineered to have an unpaired cysteine in the heavy chain, and an unnatural amino acid with the azido group was incorporated into an engineered Pseudomonas exotoxin A (PE24). The two protein molecules were conjugated site-specifically using a bifunctional linker having dibenzocyclooctyne and maleimide groups. Binding to Her2 and interaction with various Fc receptors of trastuzumab were not affected by the conjugation with PE24. The trastuzumab-PE24 conjugate was cytotoxic to Her2-overexpressing cell lines, which involved the inhibition of cellular protein synthesis due to the modification of elongation factor-2. CONCLUSIONS We constructed the site-specifically conjugated immunotoxin based on IgG and PE24, which induced target-specific cytotoxicity. To evaluate the molecule as a cancer therapeutic, animal studies are planned to assess tumor regression, half-life in blood, and in vivo immunogenicity. In addition, we expect that the site-specific conjugation method can be used to develop other antibody-protein conjugates for applications in therapeutics and diagnostics.
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Affiliation(s)
- Byeong Sung Lee
- Department of Molecular Science and Technology, Ajou University, 206 World cup-ro, Yeongtong-gu, Suwon, 16499 South Korea
| | - Yumi Lee
- Department of Molecular Science and Technology, Ajou University, 206 World cup-ro, Yeongtong-gu, Suwon, 16499 South Korea
| | - Jisoo Park
- Department of Molecular Science and Technology, Ajou University, 206 World cup-ro, Yeongtong-gu, Suwon, 16499 South Korea
| | - Bo Seok Jeong
- Department of Molecular Science and Technology, Ajou University, 206 World cup-ro, Yeongtong-gu, Suwon, 16499 South Korea
| | - Migyeong Jo
- Department of Applied Chemistry, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul, 02707 South Korea
| | - Sang Taek Jung
- Department of Biomedical Sciences, Graduate School of Medicine, Korea University, Seongbuk-gu, Seoul, 02841 South Korea
| | - Tae Hyeon Yoo
- Department of Molecular Science and Technology, Ajou University, 206 World cup-ro, Yeongtong-gu, Suwon, 16499 South Korea
- Department of Applied Chemistry and Biological Engineering, Ajou University, 206 World cup-ro, Yeongtong-gu, Suwon, 16499 South Korea
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Kaplan G, Mazor R, Lee F, Jang Y, Leshem Y, Pastan I. Improving the In Vivo Efficacy of an Anti-Tac (CD25) Immunotoxin by Pseudomonas Exotoxin A Domain II Engineering. Mol Cancer Ther 2018; 17:1486-1493. [PMID: 29695631 PMCID: PMC6030476 DOI: 10.1158/1535-7163.mct-17-1041] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 01/12/2018] [Accepted: 04/16/2018] [Indexed: 12/15/2022]
Abstract
Tac (CD25) is expressed on multiple hematologic malignancies and is a target for cancer therapies. LMB-2 is an extremely active anti-Tac recombinant immunotoxin composed of an Fv that binds to Tac and a 38-kDa fragment of Pseudomonas exotoxin A (PE38). Although LMB-2 has shown high cytotoxicity toward Tac-expressing cancer cells in clinical trials, its efficacy was hampered by the formation of anti-drug antibodies against the immunogenic bacterial toxin and by dose-limiting off-target toxicity. To reduce toxin immunogenicity and nonspecific toxicity, we introduced six point mutations into domain III that were previously shown to reduce T-cell immunogenicity and deleted domain II from the toxin, leaving only the 11aa furin cleavage site, which is required for cytotoxic activity. Although this strategy has been successfully implemented for mesothelin and CD22-targeting immunotoxins, we found that removal of domain II significantly lowered the cytotoxic activity of anti-Tac immunotoxins. To restore cytotoxic activity in the absence of PE domain II, we implemented a combined rational design and screening approach to isolate highly active domain II-deleted toxin variants. The domain II-deleted variant with the highest activity contained an engineered disulfide-bridged furin cleavage site designed to mimic its native conformation within domain II. We found that this approach restored 5-fold of the cytotoxic activity and dramatically improved the MTD. Both of these improvements led to significantly increased antitumor efficacy in vivo We conclude that the next-generation anti-Tac immunotoxin is an improved candidate for targeting Tac-expressing malignancies. Mol Cancer Ther; 17(7); 1486-93. ©2018 AACR.
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Affiliation(s)
- Gilad Kaplan
- Laboratory of Molecular Biology, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Ronit Mazor
- Laboratory of Molecular Biology, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Fred Lee
- Laboratory of Molecular Biology, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Youjin Jang
- Laboratory of Molecular Biology, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Yasmin Leshem
- Laboratory of Molecular Biology, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Ira Pastan
- Laboratory of Molecular Biology, Center for Cancer Research, NCI, NIH, Bethesda, Maryland.
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Plant Ribosome-Inactivating Proteins: Progesses, Challenges and Biotechnological Applications (and a Few Digressions). Toxins (Basel) 2017; 9:toxins9100314. [PMID: 29023422 PMCID: PMC5666361 DOI: 10.3390/toxins9100314] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 09/29/2017] [Accepted: 10/03/2017] [Indexed: 12/11/2022] Open
Abstract
Plant ribosome-inactivating protein (RIP) toxins are EC3.2.2.22 N-glycosidases, found among most plant species encoded as small gene families, distributed in several tissues being endowed with defensive functions against fungal or viral infections. The two main plant RIP classes include type I (monomeric) and type II (dimeric) as the prototype ricin holotoxin from Ricinus communis that is composed of a catalytic active A chain linked via a disulphide bridge to a B-lectin domain that mediates efficient endocytosis in eukaryotic cells. Plant RIPs can recognize a universally conserved stem-loop, known as the α-sarcin/ ricin loop or SRL structure in 23S/25S/28S rRNA. By depurinating a single adenine (A4324 in 28S rat rRNA), they can irreversibly arrest protein translation and trigger cell death in the intoxicated mammalian cell. Besides their useful application as potential weapons against infected/tumor cells, ricin was also used in bio-terroristic attacks and, as such, constitutes a major concern. In this review, we aim to summarize past studies and more recent progresses made studying plant RIPs and discuss successful approaches that might help overcoming some of the bottlenecks encountered during the development of their biomedical applications.
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Simon N, Antignani A, Sarnovsky R, Hewitt SM, FitzGerald D. Targeting a Cancer-Specific Epitope of the Epidermal Growth Factor Receptor in Triple-Negative Breast Cancer. J Natl Cancer Inst 2016; 108:djw028. [PMID: 27075852 PMCID: PMC5017938 DOI: 10.1093/jnci/djw028] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 10/21/2015] [Accepted: 02/05/2016] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Triple-negative breast cancers (TNBCs) are typically more aggressive and result in poorer outcomes than other breast cancers because treatment options are limited due to lack of hormone receptors or amplified human epidermal growth factor receptor 2 (HER2). Many TNBCs overexpress the epidermal growth factor receptor (EGFR) or manifest amplification of theEGFRgene, supporting EGFR as a therapeutic target. While EGFR-directed small molecule inhibitors have shown limited effectiveness in clinical settings, use of EGFR as a mechanism of delivering enzymatic cytotoxins to TNBC has not been demonstrated. METHODS Using the single-chain variable fragment (scFv) of the 806 antibody that binds only cells with overexpressed, misfolded, or mutant variants of the EGFR, a recombinant immunotoxin was engineered through gene fusion withPseudomonas aeruginosaExotoxin A (806-PE38). The potency of 806-PE38 on reducing TNBC cell growth in vitro and in xenograft models (n ≥ 6) was examined for six TNBC cell lines. All statistical tests were two-sided. RESULTS 806-PE38 statistically significantly reduced the viability of all tested TNBC lines, with IC50values below 10 ng/mL for three of six cell lines, while not affecting cells with wild-type EGFR (IC50>300 ng/mL). Systemic treatments with 806-PE38 vs vehicle resulted in statistically significantly reduced tumor burdens (806-PE38 mean = 128 mm(3)[SD = 46 mm(3)] vs vehicle mean = 749 mm(3)[SD = 395 mm(3)], P = .001) and increased median survival (806-PE38 median = 82 days vs vehicle median = 50 days,P= .01) in a MDA-MB-468 TNBC mouse xenograft. Deletion of the catalytic residue eliminated both cytotoxic activity in vitro and the reduction in tumor burden and survival (P= .52). CONCLUSIONS These data support the further development of the 806-PE38 immunotoxin as a therapeutic agent for the treatment of patients with EGFR-positive TNBC. Follow-up experiments with combination therapies will be attempted to achieve full remissions.
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Affiliation(s)
- Nathan Simon
- Affiliations of authors: Biotherapy Section, Laboratory of Molecular Biology (NS, AA, RS, DF), and Experimental Pathology Laboratory, Laboratory of Pathology (SMH), Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Antonella Antignani
- Affiliations of authors: Biotherapy Section, Laboratory of Molecular Biology (NS, AA, RS, DF), and Experimental Pathology Laboratory, Laboratory of Pathology (SMH), Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Robert Sarnovsky
- Affiliations of authors: Biotherapy Section, Laboratory of Molecular Biology (NS, AA, RS, DF), and Experimental Pathology Laboratory, Laboratory of Pathology (SMH), Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Stephen M Hewitt
- Affiliations of authors: Biotherapy Section, Laboratory of Molecular Biology (NS, AA, RS, DF), and Experimental Pathology Laboratory, Laboratory of Pathology (SMH), Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - David FitzGerald
- Affiliations of authors: Biotherapy Section, Laboratory of Molecular Biology (NS, AA, RS, DF), and Experimental Pathology Laboratory, Laboratory of Pathology (SMH), Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
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Cao Y, Marks JW, Liu Z, Cheung LH, Hittelman WN, Rosenblum MG. Design optimization and characterization of Her2/neu-targeted immunotoxins: comparative in vitro and in vivo efficacy studies. Oncogene 2013; 33:429-39. [PMID: 23376850 DOI: 10.1038/onc.2012.612] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Revised: 10/05/2012] [Accepted: 11/14/2012] [Indexed: 01/01/2023]
Abstract
Targeted therapeutics are potential therapeutic agents because of their selectivity and efficacy against tumors resistant to conventional therapy. The goal of this study was to determine the comparative activity of monovalent, engineered anti-Her2/neu immunotoxins fused to recombinant gelonin (rGel) to the activity of bivalent IgG-containing immunoconjugates. Utilizing Herceptin and its derived humanized single-chain antibody (single-chain fragment variable, designated 4D5), we generated bivalent chemical Herceptin/rGel conjugate, and the corresponding monovalent recombinant immunotoxins in two orientations, 4D5/rGel and rGel/4D5. All the constructs showed similar affinity to Her2/neu-overexpressing cancer cells, but significantly different antitumor activities. The rGel/4D5 orientation construct and Herceptin/rGel conjugate were superior to 4D5/rGel construct in in vitro and in vivo efficacy. The enhanced activity was attributed to improved intracellular toxin uptake into target cells and efficient downregulation of Her2/neu-related signaling pathways. The Her2/neu-targeted immunotoxins effectively targeted cells with Her2/neu expression level >1.5 × 10(5) sites per cell. Cells resistant to Herceptin or chemotherapeutic agents were not cross-resistant to rGel-based immunotoxins. Against SK-OV-3 tumor xenografts, the rGel/4D5 construct with excellent tumor penetration showed impressive tumor inhibition. Although Herceptin/rGel conjugate demonstrated comparatively longer serum half-life, the in vivo efficacy of the conjugate was similar to the rGel/4D5 fusion. These comparative studies demonstrate that the monovalent, engineered rGel/4D5 construct displayed comparable in vitro and in vivo antitumor efficacy as bivalent Herceptin/rGel conjugate. Immunotoxin orientation can significantly impact the overall functionality and performance of these agents. The recombinant rGel/4D5 construct with excellent tumor penetration and rapid blood clearance may reduce the unwanted toxicity when administrating to patients, and warrants consideration for further clinical evaluation.
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Affiliation(s)
- Y Cao
- Immunopharmacology and Targeted Therapy Laboratory, Department of Experimental Therapeutics, M.D. Anderson Cancer Center, Houston, TX, USA
| | - J W Marks
- Immunopharmacology and Targeted Therapy Laboratory, Department of Experimental Therapeutics, M.D. Anderson Cancer Center, Houston, TX, USA
| | - Z Liu
- Immunopharmacology and Targeted Therapy Laboratory, Department of Experimental Therapeutics, M.D. Anderson Cancer Center, Houston, TX, USA
| | - L H Cheung
- Immunopharmacology and Targeted Therapy Laboratory, Department of Experimental Therapeutics, M.D. Anderson Cancer Center, Houston, TX, USA
| | - W N Hittelman
- Immunopharmacology and Targeted Therapy Laboratory, Department of Experimental Therapeutics, M.D. Anderson Cancer Center, Houston, TX, USA
| | - M G Rosenblum
- Immunopharmacology and Targeted Therapy Laboratory, Department of Experimental Therapeutics, M.D. Anderson Cancer Center, Houston, TX, USA
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Barnea I, Ben-Yosef R, Karaush V, Benhar I, Vexler A. Targeting EGFR-positive cancer cells with cetuximab-ZZ-PE38: Results of in vitro and in vivo studies. Head Neck 2012; 35:1171-7. [DOI: 10.1002/hed.23093] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/25/2012] [Indexed: 11/09/2022] Open
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Abstract
Antibodies are among the most powerful tools in biological and biomedical research and are presently the fastest growing category of new bio-pharmaceutics. The most common format of antibody applied for therapeutic, diagnostic and analytical purposes is the IgG format. For medical applications, recombinant IgGs are made in cultured mammalian cells in a process that is too expensive to be considered for producing antibodies for diagnostic and analytical purposes. Therefore, for such purposes, mouse monoclonal antibodies or polyclonal sera from immunized animals are used. While looking for an easier and more rapid way to prepare full-length IgGs for therapeutic purposes, we recently developed and reported an expression and purification protocol for full-length IgGs, and IgG-based fusion proteins in E. coli, called "Inclonals." By applying the Inclonals technology, we could generate full-length IgGs that are genetically fused to toxins. The aim of the study described herein was to evaluate the possibility of applying the "Inclonals" technology for preparing IgG-fluorophore fusion proteins. We found that IgG fused to the green fluorescent proteins enhanced GFP (EGFP) while maintaining functionality in binding, lost most of its fluorescence during the refolding process. In contrast, we found that green fluorescent Superfolder GFP (SFGFP)-fused IgG and red fluorescent mCherry-fused IgG were functional in antigen binding and maintained fluorescence intensity. In addition, we found that we can link several SFGFPs in tandem to each IgG, with fluorescence intensity increasing accordingly. Fluorescent IgGs made in E. coli may become attractive alternatives to monoclonal or polyclonal fluorescent antibodies derived from animals.
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Affiliation(s)
- Yael Luria
- Department of Molecular Microbiology and Biotechnology; The George S. Wise Faculty of Life Sciences; Ramat Aviv, Israel
| | - Dina Raichlin
- Department of Molecular Microbiology and Biotechnology; The George S. Wise Faculty of Life Sciences; Ramat Aviv, Israel
| | - Itai Benhar
- Department of Molecular Microbiology and Biotechnology; The George S. Wise Faculty of Life Sciences; Ramat Aviv, Israel
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Unverdorben F, Färber-Schwarz A, Richter F, Hutt M, Kontermann RE. Half-life extension of a single-chain diabody by fusion to domain B of staphylococcal protein A. Protein Eng Des Sel 2012; 25:81-8. [PMID: 22238430 DOI: 10.1093/protein/gzr061] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Binding of a therapeutic protein to a long-circulating plasma protein can result in a strongly extended half-life. Among these plasma proteins, albumin and immunoglobulins are of special interest because of their exceptionally long half-life, which is to a great extent determined by recycling through the neonatal Fc receptor (FcRn). Many strategies have been established employing reversible binding to albumin, e.g. using an albumin-binding domain from streptococcal protein G. We show here that the half-life of a recombinant antibody molecule can also be prolonged by fusion to a single immunoglobulin-binding domain (IgBD) from staphylococcal protein A. This domain (domain B, SpA(B)) is composed of 56 amino acid residues and was fused to the C-terminus of a bispecific single-chain diabody (scDb). The scDb-SpA(B) fusion protein was produced in HEK293 cells and retained its antigen-binding activity as shown by enzyme-linked immunosorbent assay and flow cytometry. Furthermore, the fusion protein was capable of binding to human and mouse IgG in a pH-dependent manner. In mice, the terminal half-life of the fusion protein was improved from ∼1-2 h of the unmodified scDb to 11.8 h. Although the fusion protein did not reach the long half-life seen for IgG, our results established the applicability of a single bacterial IgBD for half-life extension purposes.
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Affiliation(s)
- Felix Unverdorben
- Institut für Zellbiologie und Immunologie, Universität Stuttgart, Allmandring 31, 70569 Stuttgart, Germany
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Cao Y, Marks JD, Huang Q, Rudnick SI, Xiong C, Hittelman WN, Wen X, Marks JW, Cheung LH, Boland K, Li C, Adams GP, Rosenblum MG. Single-chain antibody-based immunotoxins targeting Her2/neu: design optimization and impact of affinity on antitumor efficacy and off-target toxicity. Mol Cancer Ther 2011; 11:143-53. [PMID: 22090420 DOI: 10.1158/1535-7163.mct-11-0519] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Recombinant immunotoxins, consisting of single-chain variable fragments (scFv) genetically fused to polypeptide toxins, represent potentially effective candidates for cancer therapeutics. We evaluated the affinity of various anti-Her2/neu scFv fused to recombinant gelonin (rGel) and its effect on antitumor efficacy and off-target toxicity. A series of rGel-based immunotoxins were created from the human anti-Her2/neu scFv C6.5 and various affinity mutants (designated ML3-9, MH3-B1, and B1D3) with affinities ranging from 10(-8) to 10(-11) mol/L. Against Her2/neu-overexpressing tumor cells, immunotoxins with increasing affinity displayed improved internalization and enhanced autophagic cytotoxicity. Targeting indices were highest for the highest affinity B1D3/rGel construct. However, the addition of free Her2/neu extracellular domain (ECD) significantly reduced the cytotoxicity of B1D3/rGel because of immune complex formation. In contrast, ECD addition had little impact on the lower affinity constructs in vitro. In vivo studies against established BT474 M1 xenografts showed growth suppression by all immunotoxins. Surprisingly, therapy with the B1D3-rGel induced significant liver toxicity because of immune complex formation with shed Her2/neu antigen in circulation. The MH3-B1/rGel construct with intermediate affinity showed effective tumor growth inhibition without inducing hepatotoxicity or complex formation. These findings show that while high-affinity constructs can be potent antitumor agents, they may also be associated with mistargeting through the facile formation of complexes with soluble antigen leading to significant off-target toxicity. Constructs composed of intermediate-affinity antibodies are also potent agents that are more resistant to immune complex formation. Therefore, affinity is an exceptionally important consideration when evaluating the design and efficacy of targeted therapeutics.
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Affiliation(s)
- Yu Cao
- Immunopharmacology and Targeted Therapy Laboratory, Departmentof Experimental Therapeutics, University of Texas MD AndersonCancer Center, Houston, Texas 77054, USA
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Shapira S, Shapira A, Starr A, Kazanov D, Kraus S, Benhar I, Arber N. An immunoconjugate of anti-CD24 and Pseudomonas exotoxin selectively kills human colorectal tumors in mice. Gastroenterology 2011; 140:935-46. [PMID: 21147107 DOI: 10.1053/j.gastro.2010.12.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Revised: 11/25/2010] [Accepted: 12/02/2010] [Indexed: 01/17/2023]
Abstract
BACKGROUND & AIMS Effective and selective treatment options are needed for patients with colorectal cancer (CRC). The CD24 mucin-like glycoprotein is overexpressed in CRCs; monoclonal antibodies (mAbs) against CD24 inhibit tumor cell growth in vitro and in vivo. Based on the tumor-specific expression of CD24, we investigated the potential of anti-CD24 SWA11 mAb, to deliver a cytotoxic agent into CRC cells. METHODS We conjugated SWA11 to a Pseudomonas exotoxin derivative (PE38) via an Fc-binding ZZ domain from Staphylococcal protein A (which binds the Fc domain of mouse IgG2a immunoglobulins) to generate the immunotoxin SWA11-ZZ-PE38; IgG-ZZ-PE38 was used as control. Human HT-29 and COLO320 (CD24-positive) and HCT116 (CD24-negative) CRC cell lines were assayed for immunotoxin binding, cytotoxicity, viability, and apoptosis. Toxicity and antitumor efficacy were tested in mice. RESULTS The immunotoxin preserved the affinity and specificity of SWA11, bound and selectively killed CD24-expressing CRC cells via apoptosis. IC(50) values ranged from 20 to 50 ng/mL-several orders of magnitude lower than that of the mAb alone. The immunotoxins were not toxic to mice at the maximum dose of 0.75 mg/kg. Growth of HT-29 xenograft tumors was significantly reduced in mice given SWA11-ZZ-PE38 (by 78%) compared to untreated mice. CONCLUSIONS Anti-CD24 SWA11 mAb can deliver a PE exotoxin derivative to CRC cells and cause them to undergo apoptosis, without toxicity to normal tissues. This immunotoxin might be developed as a therapeutic treatment for patients with CRC.
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Affiliation(s)
- Shiran Shapira
- The Integrated Cancer Prevention Center, Tel Aviv, Israel
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Martin-Killias P, Patricia MK, Stefan N, Rothschild S, Plückthun A, Zangemeister-Wittke U. A novel fusion toxin derived from an EpCAM-specific designed ankyrin repeat protein has potent antitumor activity. Clin Cancer Res 2011; 17:100-10. [PMID: 21075824 DOI: 10.1158/1078-0432.ccr-10-1303] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Designed ankyrin repeat proteins (DARPins) hold great promise as a new class of binding molecules to overcome the limitations of antibodies for biomedical applications. Here, we assessed the potential of an epithelial cell adhesion molecule (EpCAM)-specific DARPin (Ec4) for tumor targeting as a fusion toxin with Pseudomonas aeruginosa exotoxin A. EXPERIMENTAL DESIGN DARPin Ec4 was genetically fused to a truncated form of Pseudomonas aeruginosa exotoxin A (ETA″) and expressed in Escherichia coli. The cytotoxicity of Ec4-ETA″ was measured against tumor cell lines of various histotypes in vitro. Tumor localization and antitumor activity were determined in mice bearing 2 different EpCAM-positive tumor xenografts. RESULTS Ec4-ETA″ expressed very well in soluble form in the cytoplasm of E. coli and yielded up to 40 mg after purification per liter of culture. The protein was monomeric and the disulfides of ETA″ formed spontaneously. Ec4-ETA″ bound to EpCAM with low nanomolar affinity, similar to free Ec4. Furthermore, it was highly cytotoxic against various EpCAM-positive tumor cell lines in vitro with IC(50) values less than 0.005 pmol/L. This effect was competed by free Ec4, but not by unspecific DARPins. Upon systemic administration in athymic mice, Ec4-ETA″ efficiently localized to EpCAM-positive tumors to achieve maximum accumulation 48 to 72 hours after injection, whereas an irrelevant control fusion toxin did not accumulate. Tumor targeting with Ec4-ETA″ resulted in a strong antitumor response including complete regressions in some animals. CONCLUSIONS Our data show for the first time the potential of DARPins for the generation of protein therapeutics for tumor targeting, and that Ec4-ETA″ deserves attention for clinical development.
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Shapira S, Lisiansky V, Arber N, Kraus S. Targeted immunotherapy for colorectal cancer: monoclonal antibodies and immunotoxins. Expert Opin Investig Drugs 2010; 19 Suppl 1:S67-77. [PMID: 20374033 DOI: 10.1517/13543781003737668] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Colorectal cancer (CRC) is a major health concern worldwide. It is the third most frequently diagnosed cancer and the second leading cause of cancer death. There currently are a number of treatment options for CRC, however many of them have failed to demonstrate desired therapeutic benefit. Therefore, significant efforts are being directed towards the development of new biological therapies with improved efficacy. Immunotherapy is an emerging treatment modality for a variety of cancers. Several promising treatments have already been approved by the US FDA and are being tested in clinical trials. Antibodies have been proved to be useful in cancer therapy due to their ability to recognize tumor-associated antigens expressed at higher density on malignant cells in comparison with those that are normal. Antibodies can be used as a single therapy or in combination with other therapies. A large variety of monoclonal antibodies have been developed. However, only a very few are able to kill a sufficient number of malignant cells and cause tumor regression. Hence, it is often necessary to arm the antibody with a cytotoxic agent to enhance the efficacy of the anti-tumor activity. This review provides a brief overview of some of the current agents being employed in targeted immunotherapy for CRC.
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Affiliation(s)
- Shiran Shapira
- The Integrated Cancer Prevention Center, Tel Aviv Medical Center, Israel
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Rubinstein DB, Karmely M, Pichinuk E, Ziv R, Benhar I, Feng N, Smorodinsky NI, Wreschner DH. The MUC1 oncoprotein as a functional target: Immunotoxin binding to α/β junction mediates cell killing. Int J Cancer 2009; 124:46-54. [DOI: 10.1002/ijc.23910] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Friedländer E, Barok M, Szöllősi J, Vereb G. ErbB-directed immunotherapy: Antibodies in current practice and promising new agents. Immunol Lett 2008; 116:126-40. [DOI: 10.1016/j.imlet.2007.12.001] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2007] [Accepted: 12/01/2007] [Indexed: 01/24/2023]
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