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Moradbeygi F, Ghasemi Y, Farmani AR, Hemmati S. Glucarpidase (carboxypeptidase G2): Biotechnological production, clinical application as a methotrexate antidote, and placement in targeted cancer therapy. Biomed Pharmacother 2023; 166:115292. [PMID: 37579696 DOI: 10.1016/j.biopha.2023.115292] [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: 06/23/2023] [Revised: 07/30/2023] [Accepted: 08/04/2023] [Indexed: 08/16/2023] Open
Abstract
Patients receiving high-dose methotrexate (HDMTX) for malignancies are exposed to diverse complications, including nephrotoxicity, hepatotoxicity, mucositis, myelotoxicity, neurological symptoms, and death. Glucarpidase is a recombinant carboxypeptidase G2 (CPG2) that converts MTX into nontoxic metabolites. In this study, the role of vector type, gene optimization, orientation, and host on the expression of CPG2 is investigated. The effectiveness of various therapeutic regimens containing glucarpidase is classified and perspectives on the dose adjustment based on precision medicine are provided. Conjugation with cell-penetrating peptides, human serum albumin, and polymers such as PEG and dextran for delivery, higher stability, and production of the biobetter variants of CPG2 is highlighted. Conjugation of CPG2 to F(ab՜)2 or scFv antibody fragments against tumor-specific antigens and the corresponding prodrugs for tumor-targeted drug delivery using the antibody-directed enzyme prodrug therapy (ADEPT) is communicated. Trials to reduce the off-target effects and the possibility of repeated ADEPT cycles by adding pro-domains sensitive to tumor-overexpressed proteases, antiCPG2 antibodies, CPG2 mutants with immune-system-unrecognizable epitopes, and protective polymers are reported. Intracellular cpg2 gene expression by gene-directed enzyme prodrug therapy (GDEPT) and the concerns regarding the safety and transfection efficacy of the GDEPT vectors are described. A novel bifunctional platform using engineered CAR-T cell micropharmacies, known as Synthetic Enzyme-Armed KillER (SEAKER) cells, expressing CPG2 to activate prodrugs at the tumor niche is introduced. Taken together, integrated data in this review and recruiting combinatorial strategies in novel drug delivery systems define the future directions of ADEPT, GDEPT, and SEAKER cell therapy and the placement of CPG2 therein.
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Affiliation(s)
- Fatemeh Moradbeygi
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Younes Ghasemi
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran; Pharmaceutical Sciences Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Ahmad Reza Farmani
- Tissue Engineering Department, School of Advanced Technologies in Medicine, Fasa University of Medical Sciences, Fasa, Iran
| | - Shiva Hemmati
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran; Biotechnology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.
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Engineered antibody fusion proteins for targeted disease therapy. Trends Pharmacol Sci 2021; 42:1064-1081. [PMID: 34706833 DOI: 10.1016/j.tips.2021.09.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 09/28/2021] [Accepted: 09/29/2021] [Indexed: 12/18/2022]
Abstract
Since the FDA approval of the first therapeutic antibody 35 years ago, antibody-based products have gained prominence in the pharmaceutical market. Building on the early successes of monoclonal antibodies, more recent efforts have capitalized on the exquisite specificity and/or favorable pharmacokinetic properties of antibodies by developing fusion proteins that enable targeted delivery of therapeutic payloads which are otherwise ineffective when administered systemically. This review focuses on recent engineering and translational advances for therapeutics that genetically fuse antibodies to disease-relevant payloads, including cytokines, toxins, enzymes, neuroprotective agents, and soluble factor traps. With numerous antibody fusion proteins in the clinic and other innovative molecules poised to follow suit, these potent, multifunctional drug candidates promise to be a major player in the therapeutic development landscape for years to come.
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Blas P, Tolner B, Ward J, Chester K, Hoare M. The use of a surface active agent in the protection of a fusion protein during bioprocessing. Biotechnol Bioeng 2018; 115:2760-2770. [PMID: 30102764 PMCID: PMC6334174 DOI: 10.1002/bit.26817] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 06/29/2018] [Accepted: 07/23/2018] [Indexed: 11/14/2022]
Abstract
The bioprocessing of a fusion protein is characterised by low yields and at a series of recovery and purification stages that leads to an overall 90% loss. Much of this apparent loss is due to the denaturation of a protein, missing a vital affinity ligand. However, there is evidence of the protection of degradation products which occurs in the presence of shear plus air/liquid interfaces. This study seeks out to characterise the loss and use ultra‐scale‐down studies to predict its occurrence and hence shows these may be diminished by the use of protective reagents such as Pluronic F68.
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Affiliation(s)
- Peter Blas
- Department of Biochemical Engineering, ACBE, University College London, London, UK
| | - Berend Tolner
- Department of Oncology, The Royal Free Hospital, London, UK
| | - John Ward
- Department of Biochemical Engineering, ACBE, University College London, London, UK
| | - Kerry Chester
- Department of Oncology, The Royal Free Hospital, London, UK
| | - Mike Hoare
- Department of Biochemical Engineering, ACBE, University College London, London, UK
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Sharma SK, Bagshawe KD. Translating antibody directed enzyme prodrug therapy (ADEPT) and prospects for combination. Expert Opin Biol Ther 2016; 17:1-13. [DOI: 10.1080/14712598.2017.1247802] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Surinder K. Sharma
- Research Department of Oncology, UCL Cancer Institute, University College London, London, UK
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Wang X, Zhang FC, Zhao HY, Lu XL, Sun Y, Xiong ZY, Jiang XB. Human IP10-scFv and DC-induced CTL synergistically inhibit the growth of glioma in a xenograft model. Tumour Biol 2014; 35:7781-91. [PMID: 24816916 PMCID: PMC4158415 DOI: 10.1007/s13277-014-1867-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2014] [Accepted: 03/18/2014] [Indexed: 12/23/2022] Open
Abstract
The epidermal growth factor receptor (EGFR) mutant of EGFRvIII is highly expressed in glioma cells, and the EGFRvIII-specific dendritic cell (DC)-induced tumor antigen-specific CD8(+) cytotoxic T lymphocytes (CTLs) may hold promise in cancer immunotherapy. Interferon (IFN)-γ-inducible protein (IP)-10 (IP-10) is a potent inhibitor of angiogenesis and can recruit CXCR3(+) T cells, including CD8(+) T cells, which are important for the control of tumor growth. In this study, we assessed if the combination of IP10-EGFRvIIIscFv with DC-induced CTLs would improve the therapeutic antitumor efficacy. IP10-scFv was generated by linking the human IP-10 gene with the DNA fragment for anti-EGFRvIIIscFv with a (Gly4Ser)3 flexible linker, purified by affinity chromatography, and characterized for its anti-EGFRvIII immunoreactivity and chemotactic activity. DCs were isolated from human peripheral blood monocyte cells and pulsed with EGFRvIII-peptide, then co-cultured with autologous CD8(+) T cells. BALB/c-nu mice were inoculated with human glioma U87-EGFRvIII cells in the brain and treated intracranially with IP10-scFv and/or intravenously with DC-induced CTLs for evaluating the therapeutic effect. Treatment with both IP10-scFv and EGFRvIII peptide-pulsed, DC-induced CTL synergistically inhibited the growth of glioma and prolonged the survival of tumor-bearing mice, which was accompanied by the inhibition of tumor angiogenesis and enhancement of cytotoxicity, thereby increasing the numbers of brain-infiltrating lymphocytes (BILs) and prolonging the residence time of CTLs in the tumor.
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Affiliation(s)
- Xuan Wang
- Department of Neurosurgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 430022 Wuhan, China
| | - Fang-Cheng Zhang
- Department of Neurosurgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 430022 Wuhan, China
| | - Hong-Yang Zhao
- Department of Neurosurgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 430022 Wuhan, China
| | - Xiao-Ling Lu
- National Center for International Research of Biological Targeting Diagnosis and Therapy, Guangxi Key Laboratory of Biological Targeting Diagnosis and Therapy Research, Guangxi Medical University, Nanning, 530021 Guangxi China
| | - Yun Sun
- Department of Neurosurgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 430022 Wuhan, China
| | - Zhi-Yong Xiong
- Department of Neurosurgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 430022 Wuhan, China
| | - Xiao-Bing Jiang
- Department of Neurosurgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 430022 Wuhan, China
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Andrady C, Sharma SK, Chester KA. Antibody-enzyme fusion proteins for cancer therapy. Immunotherapy 2011; 3:193-211. [PMID: 21322759 DOI: 10.2217/imt.10.90] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Advances in biomolecular technology have allowed the development of genetically fused antibody-enzymes. Antibody-enzyme fusion proteins have been used to target tumors for cancer therapy in two ways. In one system, an antibody-enzyme is pretargeted to the tumor followed by administration of an inactive prodrug that is converted to its active form by the pretargeted enzyme. This system has been described as antibody-directed enzyme prodrug therapy. The other system uses antibody-enzyme fusion proteins as direct therapeutics, where the enzyme is toxic in its own right. The key feature in this approach is that the antibody is used to internalize the toxic enzyme into the tumor cell, which activates cell-death processes. This antibody-enzyme system has been largely applied to deliver ribonucleases. This article addresses these two antibody-enzyme targeting strategies for cancer therapy from concept to (pre)clinical trials.
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Affiliation(s)
- Carima Andrady
- Cancer Research UK Targeting & Imaging Group, Department of Oncology, UCL Cancer Institute, Paul O'Gorman Building, University College London, 72 Huntley Street, London WC1E6BT, UK.
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Abstract
During the development cycle of a new antibody therapy, the therapeutic agent will be tested on subsequently more biologically complex models. New experiments' designs are based upon data gathered from prior models. New researchers who inherit the data and researchers from groups with different cultures or expertise are often called upon to interpret these data. Experiments which are not recorded consistently or employ ambiguous terminology can make interpreting these results difficult. The researcher who had originally collected the data may not be at hand to correct any misunderstanding or offer clarification and data can be unknowingly misused. This introduces an element of risk into the therapy development process. We have developed a reporting guideline for recording therapy experiments. This guideline consists of a checklist of data to be recorded from antibody therapy experiments performed in molecular, cellular, animal and clinical model.
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Forsberg G, Skartved NJ, Wallén-Öhman M, Nyhlén HC, Behm K, Hedlund G, Nederman T. Naptumomab Estafenatox, an Engineered Antibody-superantigen Fusion Protein With Low Toxicity and Reduced Antigenicity. J Immunother 2010; 33:492-9. [DOI: 10.1097/cji.0b013e3181d75820] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Shukla GS, Krag DN. Developing bifunctional beta-lactamase molecules with built-in target-recognizing module for prodrug therapy: identification of Enterobacter Cloacae P99 cephalosporinase loops suitable for randomization and phage-display selection. J Mol Recognit 2010; 22:425-36. [PMID: 19437416 DOI: 10.1002/jmr.957] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This study was focused on developing catalytically active beta-lactamase enzyme molecules that have target-recognizing sites built within their scaffold. Using phage-display approach, nine libraries were constructed by inserting the randomized linear or cysteine-constrained heptapeptides in the five different loops on the outer surface of P99 beta-lactamase molecule. The pIII signal peptide of Sec-pathway was employed for a periplasmic translocation of the beta-lactamase fusion protein, which we found more efficient than the DsbA signal peptide of SRP-pathway. The randomized heptapeptide loops replaced native amino acids between positions (34)Y-(37)K, (238)M-(246)A, (275)N-(280)A, (305)A-(311)S, or (329)I-(334)I of the P99 beta-lactamase molecules for generating the loop-1 to -5 libraries, respectively. The diversity of each loop library was judged by counting the primary and beta-lactamase-active clones. The linear peptide inserts in the loop-2 library showed the maximum number of the beta-lactamase-active clones, followed by the loop-5, loop-3, and loop-4. The insertion of the cysteine-constrained loops exhibited a dramatic loss of the enzyme-active beta-lactamase clones. The complexity of the loop-2 linear library, as determined by the frequency and diversity of amino acid distributions in the randomized region, appears consistent with the standards of other types of phage display library systems. The selection of the loop-2 linear library on streptavidin protein as a test target identified several beta-lactamase clones that specifically bound to streptavidin. In conclusion, this study identified the suitability of the loop-2 of P99 beta-lactamase for constructing a phage-display library of the beta-lactamase enzyme-active molecules that can be selected against a target. This is an enabling step in our long-term goal of developing bifunctional beta-lactamase molecules against cancer-specific targets for enzyme prodrug therapy of cancer.
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Affiliation(s)
- Girja S Shukla
- Department of Surgery and Vermont Cancer Center, University of Vermont College of Medicine, Burlington, VT 05405, USA.
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Meng XM, Yu SY, Lu SY, Ren HL, Li YS, Zhou Y, Liu ZS. Preparation and Immunological Characteristics of Broad-Spectrum Antibodies Against Poly-Recombinant Toxins from Food-Borne Pathogenic Bacteria. FOOD BIOTECHNOL 2009. [DOI: 10.1080/08905430902873445] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Ito T, Tanabe K, Yamada H, Hatta H, Nishimoto SI. Radiation- and photo-induced activation of 5-fluorouracil prodrugs as a strategy for the selective treatment of solid tumors. Molecules 2008; 13:2370-84. [PMID: 18830160 PMCID: PMC6245186 DOI: 10.3390/molecules13102370] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Revised: 09/22/2008] [Accepted: 09/22/2008] [Indexed: 12/02/2022] Open
Abstract
5-Fluorouracil (5-FU) is used widely as an anticancer drug to treat solid cancers, such as colon, breast, rectal, and pancreatic cancers, although its clinical application is limited because 5-FU has gastrointestinal and hematological toxicity. Many groups are searching for prodrugs with functions that are tumor selective in their delivery and can be activated to improve the clinical utility of 5-FU as an important cancer chemotherapeutic agent. UV and ionizing radiation can cause chemical reactions in a localized area of the body, and these have been applied in the development of site-specific drug activation and sensitization. In this review, we describe recent progress in the development of novel 5-FU prodrugs that are activated site specifically by UV light and ionizing radiation in the tumor microenvironment. We also discuss the chemical mechanisms underlying this activation.
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Fine specificity of drug-dependent antibodies reactive with a restricted domain of platelet GPIIIA. Blood 2007; 111:1234-9. [PMID: 17959856 DOI: 10.1182/blood-2007-09-112680] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Drug-induced immune thrombocytopenia is caused by drug-dependent antibodies (DDAbs) that bind tightly to platelet glycoproteins only when drug is present. How drugs mediate this interaction is not yet resolved. Several studies indicate that sites recognized by DDAbs tend to cluster in specific structural domains, suggesting they may recognize a limited number of distinct epitopes. To address this issue, we characterized the binding sites for 16 quinine-dependent antibodies thought on the basis of preliminary studies to be possibly specific for a single epitope on glycoprotein IIIa (GPIIIa). Fourteen of the antibodies reacted with a 29-kDa GPIIIa fragment comprising only the GPIIIa hybrid and plextrin-semaphorin-integrin homology domains. However, studies with mutant GPIIIa and the blocking monoclonal antibody AP3 showed that the 14 DDAbs recognize at least 6 and possibly more distinct, but overlapping, structures involving GPIIIa residues 50 to 66. The findings suggest that even antibodies specific for restricted domains on a target glycoprotein may each have a slightly different fine specificity; ie, "unique" epitopes recognized by DDAbs may be rare or nonexistent. The observations are consistent with a recently proposed model in which drug reacts noncovalently with both target protein and antibody to promote binding of an otherwise nonreactive immunoglobulin.
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Zhang Q, Zhang SH, Su MQ, Bao GQ, Liu JY, Yi J, Shen JJ, Hao XK. Guided selection of an anti-gamma-seminoprotein human Fab for antibody directed enzyme prodrug therapy of prostate cancer. Cancer Immunol Immunother 2007; 56:477-89. [PMID: 16868778 PMCID: PMC11030898 DOI: 10.1007/s00262-006-0202-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2006] [Accepted: 06/12/2006] [Indexed: 11/28/2022]
Abstract
BACKGROUND The HAMA response is a major challenge when murine antibodies are repeatedly administered for antibody directed enzyme prodrug therapy in vivo. In this study we have achieved humanization of the anti-gamma-seminoprotein E(4)B(7) murine mAb by guided selection. METHODS Using optimal Ig Fab primers, human Fd and CL gene repertoires were amplified by RT-PCR from PBMCs of prostate cancer patients. The human Lc gene repertoire was first paired with the murine Fd gene of E(4)B(7) mAb to construct a pComb3X hybrid Fab display library. This hybrid library was screened with purified gamma-seminoprotein antigen. The human Fd gene repertoire was then paired with the selected human Lc to construct a fully human Fab library. After four more rounds of panning, completely human Fab antibodies specific for gamma-seminoprotein were selected and further identified. RESULTS First, using the E(4)B(7) Fd gene as a template, light chain shuffling was achieved by panning the hybrid library. Then, using the selected Lc as a template, a human Fab antibody against gamma-seminoprotein was produced through heavy chain Fd shuffling. Western blotting, ELISA, and flow cytometry results demonstrated that the resulting human Fab antibody resembled the parental E(4)B(7) mAb in that they both recognized the same epitope with similar affinities. Fluorescent cell staining and immunohistochemistry analysis further confirmed that this newly constructed human anti-gamma-seminoprotein Fab antibody indeed specifically bound prostate cancer cells and tissue. CONCLUSIONS Through guided-selection, we successfully produced a human anti-gamma-seminoprotein Fab antibody. This work lays the foundation for optimal antibody-directed enzyme prodrug therapy of prostate cancer using a fully human Fab antibody.
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Affiliation(s)
- Qing Zhang
- Department of Clinical Laboratory, Xijing Hospital, Fourth Military Medical University, Xi’an, 710032 People’s Republic of China
- Department of Clinical Laboratory, Tangdu Hospital, Fourth Military Medical University, Xi’an, 710038 People’s Republic of China
| | - Si-He Zhang
- Cell Engineering Research Center, State Key Laboratory of Cancer Biology, Fourth Military Medical University, Xi’an, 710032 People’s Republic of China
| | - Ming-Quan Su
- Department of Clinical Laboratory, Xijing Hospital, Fourth Military Medical University, Xi’an, 710032 People’s Republic of China
| | - Guo-Qiang Bao
- Department of General Surgery, Tangdu Hospital, Fourth Military Medical University, Xi’an, 710038 People’s Republic of China
| | - Jia-Yun Liu
- Department of Clinical Laboratory, Xijing Hospital, Fourth Military Medical University, Xi’an, 710032 People’s Republic of China
| | - Jing Yi
- Department of Clinical Laboratory, Xijing Hospital, Fourth Military Medical University, Xi’an, 710032 People’s Republic of China
| | - Jian-Jun Shen
- Department of Clinical Laboratory, Xijing Hospital, Fourth Military Medical University, Xi’an, 710032 People’s Republic of China
| | - Xiao-Ke Hao
- Department of Clinical Laboratory, Xijing Hospital, Fourth Military Medical University, Xi’an, 710032 People’s Republic of China
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Shukla GS, Murray CJ, Estabrook M, Shen GP, Schellenberger V, Krag DN. Towards a ligand targeted enzyme prodrug therapy: Single round panning of a β-lactamase scaffold library on human cancer cells. Int J Cancer 2007; 120:2233-42. [PMID: 17285581 DOI: 10.1002/ijc.22138] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A novel beta-lactamase scaffold library in which the target-binding moiety is built into the enzyme was generated using phage display technology. The binding element is composed of a fully randomized 8 amino acid loop inserted at position between Y34 and K37 on the outer surface of Enterobacter cloacae P99 cephalosporinase (beta-lactamase, E.C. 3.5.2.6) with all library members retaining catalytic activity. The frequency and diversity of amino acids distributions in peptide inserts from library clones were analyzed. The complexity of the randomized loop appears consistent with standards of other types of phage display library systems. The library was panned against SKBR3 human breast cancer cells in 1 round using rolling circle amplification of phage DNA to recover bound phage. Individual beta-lactamase clones, independent of phage, were rapidly assessed for their binding to SKBR3 cells using a simple high throughput screen based on cell-bound beta-lactamase activity. SKBR3 cell-binding beta-lactamase enzymes were also shown to bind specifically using an immunochemical method. Selected beta-lactamase clones were further studied for their protein expression, enzyme activity and binding to nontumor cell-lines. Overall, the approach outlined here offers the opportunity of rapidly selecting targeted beta-lactamase ligands that may have a potential for their use in enzyme prodrug therapy with cephalosporin-based prodrugs. It is expected that a similar approach will be useful in developing tumor-targeting molecules of several other enzyme candidates of cancer prodrug therapy.
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Affiliation(s)
- Girja S Shukla
- Department of Surgery, Vermont Comprehensive Cancer Center, and University of Vermont College of Medicine, 89 Beaumont Avenue, Burlington, VT 05405, USA.
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Abstract
Antibody-directed enzyme prodrug therapy was conceived as a means of restricting the action of cytotoxic drugs to tumor sites. Since antigenic targets were a central component of the approach, colonic cancer, with its virtually universal expression of carcinoembryonic antigen at the cellular level, presented an obvious starting point. The principle of antibody-directed enzyme prodrug therapy is to use an antibody directed at a tumor-associated antigen to vector an enzyme to tumor sites. The enzyme should be retained at tumor sites after it has cleared from blood and normal tissues. A nontoxic prodrug, a substrate for the enzyme, is then given and, by cleaving an inactivating component from the prodrug, a potent cytotoxic agent is generated. One of the potential advantages of such a system is that a small cytotoxic agent, generated within a tumor site, is much more diffusible than a large antibody molecule. Moreover, failure to express the target antigen by cancer cells does not protect them from the bystander action of the cytotoxic agent. This review will primarily consider the studies of the London group since this is the only group that has so far reported clinical trials and it is only through clinical trials that the requirements of a successful antibody-directed enzyme prodrug therapy system can be identified.
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Affiliation(s)
- Kenneth D Bagshawe
- Imperial College London, Department of Medical Oncology, Charing Cross Campus, Fulham Palace Road, London W6 8RF, UK.
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Abstract
Antibody therapies have become an important component in the management of malignant disease. Recombinant technology offers enormous opportunities to tailor antibodies to meet clinical requirements. This includes the reduction of immunogenicity and the development of smaller antibody fragments that can be incorporated into fusion proteins. Antibodies can block tumour growth factors or their receptors, activate immunological attack on the tumour, or be used to deliver payloads such as radioisotopes, cytotoxic drugs or toxins. Pretargeting includes streptavidin/biotin systems and antibody-directed enzyme prodrug therapy (ADEPT). ADEPT uses an antibody-enzyme complex to deliver a prodrug-activating enzyme to tumours for selective prodrug conversion at the tumour site. New antibody targets, refined antibodies, antibody fusion proteins, combination therapies and the use of antibodies as adjuvant therapy are important topics in the development of antibody therapy against cancer.
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Affiliation(s)
- D K Wilkins
- Royal Free and University College Medical School, University College London (Hampstead Campus), Department of Oncology, Rowland Hill Street, London, NW3 2PF, UK
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Hao XK, Liu JY, Yue QH, Wu GJ, Bai YJ, Yin Y. In vitro and in vivo prodrug therapy of prostate cancer using anti-gamma-Sm-scFv/hCPA fusion protein. Prostate 2006; 66:858-66. [PMID: 16491483 DOI: 10.1002/pros.20402] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Raising selectivity to tumor cells is a major challenge for most chemotherapy drugs. One of approaches to realizing this goal is antibody-directed enzyme prodrug therapy (ADEPT). This study was done to investigate the curative effect of a new ADEPT system for the treatment of prostate cancer. METHODS Methotrexate (MTX) prodrugs were synthesized and anti-seminoprotein (SM) single-chain antibody/human carboxypeptidase-A fusion protein (scFv/hCPA) was prepared. Therapeutic effects of this ADEPT system were evaluated. RESULTS The synthesis of prodrugs was successful and the prodrugs were confirmed no cytotoxicity, but hydrolysis with tumor-targeted scFv/hCPA fusion protein gave 1,000-fold higher cytotoxicity than MTX-alpha-Phe only. Cell cycle assays showed that tumor cells were arrested in the S phase after ADEPT treatment; furthermore, tumors were inhibited significantly in scFv/hCPA and MTX-alpha-Phe treated mice. CONCLUSIONS Our results suggest that targeted activation cytotoxicity against established prostate cancer by scFv/hCPA mediated ADEPT is tumor-specific and has no systemic toxicity in vitro and in vivo.
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Affiliation(s)
- Xiao-Ke Hao
- Department of Clinical Laboratory, Xijing Hospital, Fourth Military Medical University, Xi'an, China
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Shukla GS, Krag DN. Selective delivery of therapeutic agents for the diagnosis and treatment of cancer. Expert Opin Biol Ther 2006; 6:39-54. [PMID: 16370913 DOI: 10.1517/14712598.6.1.39] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Research activity aimed towards achieving specific and targeted delivery of cancer therapeutics has expanded tremendously in the last decade, resulting in new ways of directing drugs to tumours, as well as new types of drugs. The available strategies exploit differences in the nature of normal and cancer cells and their microenvironment. The discovery and validation of cancer-associated markers, as well as corresponding ligands, is pivotal for developing selective delivery technology for cancer. Although most current clinical trials are either monoclonal antibody- or gene-based, methodological advances in combinatorial libraries of peptides, single chain variable fragments and small organic molecules are expected to change this scenario in the near future. Nanotechnology platforms today allow systematic and modular combinations of therapeutic agents and tumour-binding moieties that may generate novel, personalised agents for selective delivery in cancer. This paper discusses recent developments and future prospects of targeted delivery technologies in the management of cancer.
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Affiliation(s)
- Girja S Shukla
- Vermont Comprehensive Cancer Center, Department of Surgery, University of Vermont College of Medicine, Burlington, VT 05405, USA.
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Bagshawe KD, Sharma SK, Begent RHJ. Antibody-directed enzyme prodrug therapy (ADEPT) for cancer. Expert Opin Biol Ther 2005; 4:1777-89. [PMID: 15500406 DOI: 10.1517/14712598.4.11.1777] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Antibody-directed enzyme prodrug therapy (ADEPT) aims to restrict the cytotoxic action to tumour sites. The obstacles to achieve this were recognised at the outset, but time and experience have given these better definition. The development of fusion proteins has provided the means of making consistent antibody-enzyme constructs on an adequate scale, and glycosylation has provided the means to control the clearance of enzyme from non-tumour sites. Human enzymes have yet to be tested in a clinical setting, and there are pointers indicating that the immunological response to foreign enzymes can be overcome. The relatively small number of purpose-designed prodrugs tested so far leaves this an area ripe for further development. The ongoing iterative process between preclinical and clinical studies is critical to achieving the objective.
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Affiliation(s)
- Kenneth D Bagshawe
- Department of Oncology, Royal Free & University College Medical School, University College London, UK
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Sharma SK, Pedley RB, Bhatia J, Boxer GM, El-Emir E, Qureshi U, Tolner B, Lowe H, Michael NP, Minton N, Begent RHJ, Chester KA. Sustained Tumor Regression of Human Colorectal Cancer Xenografts Using a Multifunctional Mannosylated Fusion Protein in Antibody-Directed Enzyme Prodrug Therapy. Clin Cancer Res 2005. [DOI: 10.1158/1078-0432.814.11.2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Purpose: Antibody-directed enzyme prodrug therapy (ADEPT) requires highly selective antibody-mediated delivery of enzyme to tumor. MFE-CP, a multifunctional genetic fusion protein of antibody and enzyme, was designed to achieve this by two mechanisms. First by using a high affinity and high specificity single chain Fv antibody directed to carcinoembryonic antigen. Second by rapid removal of antibody-enzyme from normal tissues by virtue of post-translational mannosylation. The purpose of this paper is to investigate these dual functions in an animal model of pharmacokinetics, pharmacodynamics, toxicity, and efficacy.
Experimental Design: MFE-CP was expressed in the yeast Pichia pastoris and purified via an engineered hexahistidine tag. Biodistribution and therapeutic effect of a single ADEPT cycle (1,000 units/kg MFE-CP followed by 70 mg/kg ZD2767P prodrug at 6, 7, and 8 hours) and multiple ADEPT cycles (9-10 cycles within 21-24 days) was studied in established human colon carcinoma xenografts, LS174T, and SW1222.
Results: Selective localization of functional enzyme in tumors and rapid clearance from plasma was observed within 6 hours, resulting in tumor to plasma ratios of 1,400:1 and 339:1, respectively for the LS174T and SW1222 models. A single ADEPT cycle produced reproducible tumor growth delay in both models. Multiple ADEPT cycles significantly enhanced the therapeutic effect of a single cycle in the LS174T xenografts (P = 0.001) and produced regressions in the SW1222 xenografts (P = 0.0001), with minimal toxicity.
Conclusions: MFE-CP fusion protein, in combination with ZD2767P, provides a new and successful ADEPT system, which offers the potential for multiple cycles and antitumor efficacy. These results provide a basis for the next stage in clinical development of ADEPT.
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Affiliation(s)
- Surinder K. Sharma
- 1CR UK Targeting and Imaging Group, Department of Oncology, Royal Free and University College Medical School, Royal Free Campus, London, United Kingdom
| | - R. Barbara Pedley
- 1CR UK Targeting and Imaging Group, Department of Oncology, Royal Free and University College Medical School, Royal Free Campus, London, United Kingdom
| | - Jeetendra Bhatia
- 1CR UK Targeting and Imaging Group, Department of Oncology, Royal Free and University College Medical School, Royal Free Campus, London, United Kingdom
| | - Geoffrey M. Boxer
- 1CR UK Targeting and Imaging Group, Department of Oncology, Royal Free and University College Medical School, Royal Free Campus, London, United Kingdom
| | - Ethaar El-Emir
- 1CR UK Targeting and Imaging Group, Department of Oncology, Royal Free and University College Medical School, Royal Free Campus, London, United Kingdom
| | - Uzma Qureshi
- 1CR UK Targeting and Imaging Group, Department of Oncology, Royal Free and University College Medical School, Royal Free Campus, London, United Kingdom
| | - Berend Tolner
- 1CR UK Targeting and Imaging Group, Department of Oncology, Royal Free and University College Medical School, Royal Free Campus, London, United Kingdom
| | - Helen Lowe
- 1CR UK Targeting and Imaging Group, Department of Oncology, Royal Free and University College Medical School, Royal Free Campus, London, United Kingdom
| | - N. Paul Michael
- 2Center for Applied Microbiology and Research, Porton Down, Salisbury, Wiltshire, United Kingdom; and
| | - Nigel Minton
- 3Institute of Infections, Immunity and Inflammation, Queens Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Richard H. J. Begent
- 1CR UK Targeting and Imaging Group, Department of Oncology, Royal Free and University College Medical School, Royal Free Campus, London, United Kingdom
| | - Kerry A. Chester
- 1CR UK Targeting and Imaging Group, Department of Oncology, Royal Free and University College Medical School, Royal Free Campus, London, United Kingdom
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Mayer A, Sharma SK, Tolner B, Minton NP, Purdy D, Amlot P, Tharakan G, Begent RHJ, Chester KA. Modifying an immunogenic epitope on a therapeutic protein: a step towards an improved system for antibody-directed enzyme prodrug therapy (ADEPT). Br J Cancer 2004; 90:2402-10. [PMID: 15162148 PMCID: PMC2409521 DOI: 10.1038/sj.bjc.6601888] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Carboxypeptidase G2 (CP) is a bacterial enzyme, which is targeted to tumours by an antitumour antibody for local prodrug activation in antibody-directed enzyme prodrug therapy (ADEPT). Repeated cycles of ADEPT are desirable but are hampered by human antibody response to CP (HACA). To address this, we aimed to identify and modify clinically important immunogenic sites on MFECP, a recombinant fusion protein of CP with MFE-23, a single chain Fv (scFv) antibody. A discontinuous conformational epitope at the C-terminus of the CP previously identified by the CM79 scFv antibody (CM79-identified epitope) was chosen for study. Modification of MFECP was achieved by mutations of the CM79-identified epitope or by addition of a hexahistidine tag (His-tag) to the C-terminus of MFECP, which forms part of the epitope. Murine immunisation experiments with modified MFECP showed no significant antibody response to the CM79-identified epitope compared to A5CP, an unmodified version of CP chemically conjugated to an F(ab)(2) antibody. Success of modification was also demonstrated in humans because patients treated with His-tagged MFECP had a significantly reduced antibody response to the CM79-identified epitope, compared to patients given A5CP. Moreover, the polyclonal antibody response to CP was delayed in both mice and patients given modified MFECP. This increases the prospect of repeated treatment with ADEPT for effective cancer treatment.
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Affiliation(s)
- A Mayer
- Department of Oncology, Royal Free and University College Medical School, University College London, Rowland Hill Street, London NW3 2PF, UK.
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Cheung NKV, Guo HF, Modak S, Cheung IY. Anti-idiotypic antibody as the surrogate antigen for cloning scFv and its fusion proteins. HYBRIDOMA AND HYBRIDOMICS 2002; 21:433-43. [PMID: 12573107 DOI: 10.1089/153685902321043963] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Single-chain variable fragment (ScFv) is a versatile building block for novel targeting constructs. However, a reliable screening and binding assay is often the limiting step for antigens that are difficult to clone or purify. Anti-idiotypic antibodies may be useful as surrogate antigens for cloning scFv and their fusion proteins. 8H9 is a murine IgG(1) monoclonal antibody (MAb) specific for a novel antigen expressed on the cell surface of a wide spectrum of human solid tumors, but not in normal tissues. Rat anti-8H9-idiotypic hybridomas (clones 2E9, 1E12, and 1F11) were produced by somatic cell fusion between rat lymphocytes and mouse SP2/0 myeloma. In direct binding assays enzyme-linked immunosorbant assay--(ELISA)--they were specific for the 8H9 idiotope. Using 2E9 as the surrogate antigen, 8H9-scFv was cloned from hybridoma cDNA by phage display. 8H9scFv was then fused to human-gamma1-CH2-CH3 cDNA for transduction into CHO and NSO cells. High expressors of mouse scFv-human Fc chimeric antibody were selected. The secreted homodimer reacted specifically with antigen-positive tumor cells by ELISA and by flow cytometry, inhibitable by the anti-idiotypic antibody. The reduced size resulted in a shorter half-life in vivo, while achieving comparable tumor to nontumor ratio as the native antibody 8H9. However, its in vitro activity in antibody-dependent cell-mediated cytotoxicity was modest.
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Affiliation(s)
- Nai-Kong V Cheung
- Department of Pediatrics, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.
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Abstract
This synopsis attempts to summarize progress made in radioimmunotherapy (RIT) by the end of the 20th century addressing the problems, possible solutions, and recent developments. The reduction of minimal residual disease in an adjuvant setting appears to be a feasible goal for RIT utilizing short-range alpha-emitters. RIT has been more successful in the radiosensitive hematologic malignancies, for example lymphomas and leukemias as compared with small solid tumors. Several radiopharmaceuticals seem near approval for RIT in patients with non-Hodgkin's lymphoma (NHL) as therapeutic responses, including complete responses, are common. Obstacles to successful RIT have been recognized and strategies to overcome these hurdles and to improve efficacy are continuously being developed resulting in encouraging outcome particularly with locoregional routes of administration in solid tumors. Systemic RIT for solid tumors will need manipulating the tumor-host to improve the tumor uptake and retention of radioimmunoconjugates (RICs). The utilization of radiometals, stable chelators, biodegradable linkers and bone marrow transplantation should be able to deliver the radiation dose required for successful treatment. In conjunction with additional synergistic agents, RIT is likely to have a great impact on the treatment of solid tumors. The ability to generate new constructs, such as bivalent antibodies or fusion proteins incorporating two different functional proteins opens exciting opportunities for new therapeutic modalities. These developments will hopefully offset the impediments to the successful use of RIT.
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Affiliation(s)
- S K Imam
- Department of Nuclear Medicine and Clinical Ultrasound, Liverpool Hospital, Elizabeth Street, Liverpool, Sydney NSW2170, Australia.
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Wang J, Ensor C, Dubuc GJ, Narang SA, Daunert S. Genetically fused single-chain anti-Salmonella antibody with aequorin: a bioluminescence immunoassay for a Salmonella antigen. Anal Chim Acta 2001. [DOI: 10.1016/s0003-2670(01)00852-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Bhatia J, Sharma SK, Chester KA, Pedley RB, Boden RW, Read DA, Boxer GM, Michael NP, Begent RHJ. Catalytic activity of anin vivo tumor targeted anti-CEA scFv::carboxypeptidase G2 fusion protein. Int J Cancer 2000. [DOI: 10.1002/(sici)1097-0215(20000215)85:4<571::aid-ijc20>3.0.co;2-1] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Verhaar-Langereis MJ, Zonnenberg BA, de Klerk JM, Blijham GH. Radioimmunodiagnosis and therapy. Cancer Treat Rev 2000; 26:3-10. [PMID: 10660488 DOI: 10.1053/ctrv.1999.0146] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Although promising results with radioimmunotherapy and radioimmunodiagnosis in haematological diseases, have been reported, they are less encouraging results in solid tumours. Experimental mathematical models suggest that optimization of antibody-based therapy and diagnosis is possible and that further research towards improvement is warranted. In this review, the major problems of radioimmunotherapy and diagnosis are discussed. Particular items adressed include tumour uptake of antibodies and antibody-fragments, the target/non-target ratio, immunogenicity and the selection of radionuclides.
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Affiliation(s)
- M J Verhaar-Langereis
- Department of Internal Medicine/Oncology, University Medical Centre Utrecht, The Netherlands
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Bourin P, Servat A, Lataillade JJ, Goyffon M, Vaux D, Billiald P. Immunolabeling of CD3-positive lymphocytes with a recombinant single-chain antibody/alkaline phosphatase conjugate. Biol Chem 2000; 381:173-8. [PMID: 10746749 DOI: 10.1515/bc.2000.023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
G3(3) is a novel murine monoclonal antibody directed against the CD3 antigen of human T lymphocytes which could be used to analyze lymphoid malignancies. We have produced and characterized a recombinant colorimetric immunoconjugate with the antigen-binding specificity of antibody G3(3). A gene encoding a single-chain antibody variable fragment (scFv) was assembled using the original hybridoma cells as a source of antibody variable heavy (VH) and variable light (VL) chain genes. The chimeric gene was introduced into a prokaryotic expression vector in order to produce a soluble scFv fused to bacterial alkaline phosphatase. DNA sequencing and Western blotting analyses demonstrated the integrity of the soluble immunoconjugate recovered from induced recombinant bacteria. The scFv/AP protein was bifunctional and similar in immunoreactivity to the parent G3(3) antibody. Flow cytometry and immunostaining experiments confirmed that the activity of the scFv/AP protein compares favourably with that of the parent antibody. The scFv/AP conjugate was bound to CD3 antigen at the surface of T cells and was directly detected by its enzymatic activity. Thus this novel fusion protein has potential applications as an immunodiagnostic reagent.
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Affiliation(s)
- P Bourin
- Centre de Transfusion Sanguine des Armées, Clamart, France
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Abstract
There is a need to improve on existing targeting technologies in order to develop effective cancer therapy. We have investigated this for colorectal cancer using antibodies directed against carcinoembryonic antigen (CEA). Chemical and molecular protein engineering has been used to produce antibody molecules which differ in molecular weight, affinity, valency and specificity. These have been characterised and tested in animal tumour models and clinical trials to test the parameters important for optimising tumour penetration, increasing residence time in viable areas of the tumour, accelerating clearance from normal tissues and improving therapeutic efficacy.
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Affiliation(s)
- A Mayer
- CRC Targeting and Imaging Group, Department of Oncology, Royal Free and University College Medical School, UCL, Royal Free Campus, Rowland Hill Street, London, UK
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Feng X, Pak RH, Kroger LA, Moran JK, DeNardo DG, Meares CF, DeNardo GL, DeNardo SJ. New anti-Cu-TETA and anti-Y-DOTA monoclonal antibodies for potential use in the pre-targeted delivery of radiopharmaceuticals to tumor. Hybridoma (Larchmt) 1998; 17:125-32. [PMID: 9627052 DOI: 10.1089/hyb.1998.17.125] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Monoclonal antibodies were raised against yttrium(III)-1, 4, 7, 10-tetraazacyclododecane-N,N',N''N'''--tetraacetic acid (Y-DOTA) and copper(II)-1, 4, 8, 11-tetraazacyclotetradecane-N,N',N'',N'''-tetraacetic acid (Cu-TETA). Four hybridomas with high Y-DOTA binding activity and one hybridoma with Cu-TETA activity were selected. MAbs were purified from mouse ascites by Protein A affinity chromatography and characterized. Affinity constants were determined by equilibrium dialysis and the highest affinity Y-DOTA MAb (K(aff) = 1.9 x 10(8) M(-1)) was further characterized by competitive ELISA. Gd-DOTA competed as well as Y-DOTA, whereas In-DOTA required 740x higher concentrations for 50% inhibition of this Y-DOTA MAb binding to human serum albumin-Y-DOTA-coated microtiter plates. These anti-metal chelate MAbs have potential use as vehicles for the pretargeted delivery of radiometal chelates to tumors.
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Affiliation(s)
- X Feng
- Division of Hematology/Oncology, University of California Davis Medical Center, Sacramento 95816, USA
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Abstract
Antibody-directed enzyme prodrug therapy (ADEPT) is a therapeutic strategy which aims to improve the selectivity of anticancer drugs. ADEPT is a two-step antibody targeting system that has benefits over a one-step chemo-, toxin- or radioimmunoconjugate. The basic principles of ADEPT are discussed alongside the requirements of the components: antibodies, enzymes and prodrugs. The design and syntheses of prodrugs are detailed particularly prodrug/drug systems of potential clinical use, the rationale behind their design and the in vitro and in vivo results obtained. The main features of ADEPT, such as targeting of cancer cells by the antibody-enzyme conjugates, enzymic activation of the prodrugs, selection of the prodrug/drug and enzyme/prodrug systems are reviewed.
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Begent RH, Verhaar MJ, Chester KA, Casey JL, Green AJ, Napier MP, Hope-Stone LD, Cushen N, Keep PA, Johnson CJ, Hawkins RE, Hilson AJ, Robson L. Clinical evidence of efficient tumor targeting based on single-chain Fv antibody selected from a combinatorial library. Nat Med 1996; 2:979-84. [PMID: 8782454 DOI: 10.1038/nm0996-979] [Citation(s) in RCA: 179] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We present a system for cancer targeting based on single-chain Fv (scFv) antibodies selected from combinatorial libraries, produced in bacteria and purified by using an engineered tag. Combinatorial libraries of scFv genes contain great diversity, and scFv antibodies with characteristics optimized for a particular task can be selected from them using filamentous bacteriophage. We illustrate the benefits of this system by imaging patients with carcinoembryonic antigen (CEA)-producing cancers using an iodine-123 labeled scFv anti-CEA selected for high affinity. All known tumor deposits were located, and advantages over current imaging technology are illustrated. ScFvs are produced in a cloned form and can be readily engineered to have localizing and therapeutic functions that will be applicable in cancer and other diseases.
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Affiliation(s)
- R H Begent
- Department of Clinical Oncology, Royal Free Hospital, School of Medicine, London, UK
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