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Borrok MJ, Li Y, Harvilla PB, Vellalore Maruthachalam B, Tamot N, Prokopowitz C, Chen J, Venkataramani S, Grewal IS, Ganesan R, Singh S. Conduit CAR: Redirecting CAR T-Cell Specificity with A Universal and Adaptable Bispecific Antibody Platform. CANCER RESEARCH COMMUNICATIONS 2022; 2:146-157. [PMID: 36874404 PMCID: PMC9980914 DOI: 10.1158/2767-9764.crc-21-0150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Revised: 01/08/2022] [Accepted: 03/09/2022] [Indexed: 11/16/2022]
Abstract
The success of chimeric antigen receptor (CAR) T-cell therapy against hematologic malignancies has altered the treatment paradigm for patients with these diseases. Nevertheless, the occurrence of relapse due to antigen escape or heterogeneous antigen expression on tumors remains a challenge for first-generation CAR T-cell therapies as only a single tumor antigen can be targeted. To address this limitation and to add a further level of tunability and control to CAR T-cell therapies, adapter or universal CAR T-cell approaches use a soluble mediator to bridge CAR T cells with tumor cells. Adapter CARs allow simultaneous or sequential targeting of multiple tumor antigens, control of immune synapse geometry, dose control, and the potential for improved safety. Herein, we described a novel CAR T-cell adapter platform that relies on a bispecific antibody (BsAb) targeting both a tumor antigen and the GGGGS (G4S) linker commonly used in single-chain Fv (ScFv) domains expressed on CAR T-cell surfaces. We demonstrated that the BsAb can bridge CAR T cells to tumor cells and potentiate CAR T-cell activation, proliferation, and tumor cell cytolysis. The cytolytic activity of CAR T-cells was redirected to different tumor antigens by changing the BsAb in a dose-dependent manner. This study highlights the potential of G4S-displaying CAR T cells to be redirected to engage alternative tumor-associated antigens (TAA). Significance New approaches are needed to address relapsed/refractory disease and manage potential toxicities associated with CAR T-cell therapy. We describe an adapter CAR approach to redirect CAR T cells to engage novel TAA-expressing cells via a BsAb targeting a linker present on many clinical CAR T-cell therapeutics. We anticipate the use of such adapters could increase CAR T-cell efficacy and reduce potential CAR-associated toxicities.
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Affiliation(s)
- M Jack Borrok
- Janssen BioTherapeutics, Spring House, Pennsylvania.,M. Jack Borrok and Yonghai Li contributed equally to this article
| | - Yonghai Li
- Janssen BioTherapeutics, Spring House, Pennsylvania.,M. Jack Borrok and Yonghai Li contributed equally to this article
| | | | | | - Ninkka Tamot
- Janssen BioTherapeutics, Spring House, Pennsylvania
| | | | - Jun Chen
- Janssen BioTherapeutics, Spring House, Pennsylvania
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Argiriadi MA, Benatuil L, Dubrovska I, Egan DA, Gao L, Greischar A, Hardman J, Harlan J, Iyer RB, Judge RA, Lake M, Perron DC, Sadhukhan R, Sielaff B, Sousa S, Wang R, McRae BL. CD40/anti-CD40 antibody complexes which illustrate agonist and antagonist structural switches. BMC Mol Cell Biol 2019; 20:29. [PMID: 31382872 PMCID: PMC6683420 DOI: 10.1186/s12860-019-0213-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 07/17/2019] [Indexed: 01/20/2023] Open
Abstract
Background CD40 is a 48 kDa type I transmembrane protein that is constitutively expressed on hematopoietic cells such as dendritic cells, macrophages, and B cells. Engagement of CD40 by CD40L expressed on T cells results in the production of proinflammatory cytokines, induces T helper cell function, and promotes macrophage activation. The involvement of CD40 in chronic immune activation has resulted in CD40 being proposed as a therapeutic target for a range of chronic inflammatory diseases. CD40 antagonists are currently being explored for the treatment of autoimmune diseases and several anti-CD40 agonist mAbs have entered clinical development for oncological indications. Results To better understand the mode of action of anti-CD40 mAbs, we have determined the x-ray crystal structures of the ABBV-323 (anti-CD40 antagonist, ravagalimab) Fab alone, ABBV-323 Fab complexed to human CD40 and FAB516 (anti-CD40 agonist) complexed to human CD40. These three crystals structures 1) identify the conformational CD40 epitope for ABBV-323 recognition 2) illustrate conformational changes which occur in the CDRs of ABBV-323 Fab upon CD40 binding and 3) develop a structural hypothesis for an agonist/antagonist switch in the LCDR1 of this proprietary class of CD40 antibodies. Conclusions The structure of ABBV-323 Fab demonstrates a unique method for antagonism by stabilizing the proposed functional antiparallel dimer for CD40 receptor via novel contacts to LCDR1, namely residue position R32 which is further supported by a closely related agonist antibody FAB516 which shows only monomeric recognition and no contacts with LCDR1 due to a mutation to L32 on LCDR1. These data provide a structural basis for the full antagonist activity of ABBV-323. Electronic supplementary material The online version of this article (10.1186/s12860-019-0213-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Maria A Argiriadi
- AbbVie Bioresearch Center, 381 Plantation Street, Worcester, MA, 01605, USA.
| | - Lorenzo Benatuil
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA, 01605, USA
| | | | - David A Egan
- AbbVie Inc., 1 North Waukegan Road, North Chicago, IL, 60064, USA
| | - Lei Gao
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA, 01605, USA
| | - Amy Greischar
- AbbVie Inc., 1 North Waukegan Road, North Chicago, IL, 60064, USA
| | - Jennifer Hardman
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA, 01605, USA
| | - John Harlan
- AbbVie Inc., 1 North Waukegan Road, North Chicago, IL, 60064, USA
| | - Ramesh B Iyer
- AbbVie Inc., 1 North Waukegan Road, North Chicago, IL, 60064, USA
| | - Russell A Judge
- AbbVie Inc., 1 North Waukegan Road, North Chicago, IL, 60064, USA
| | - Marc Lake
- AbbVie Inc., 1 North Waukegan Road, North Chicago, IL, 60064, USA
| | - Denise C Perron
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA, 01605, USA
| | | | - Bernhard Sielaff
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA, 01605, USA
| | - Silvino Sousa
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA, 01605, USA
| | - Rui Wang
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA, 01605, USA
| | - Bradford L McRae
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA, 01605, USA
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Computational Prediction of the Epitopes of HA1 Protein of Influenza Viruses to its Neutralizing Antibodies. Antibodies (Basel) 2018; 8:antib8010002. [PMID: 31544808 PMCID: PMC6640696 DOI: 10.3390/antib8010002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 12/11/2018] [Accepted: 12/19/2018] [Indexed: 11/17/2022] Open
Abstract
In this work, we have used a new method to predict the epitopes of HA1 protein of influenza virus to several antibodies HC19, CR9114, BH151 and 4F5. While our results reproduced the binding epitopes of H3N2 or H5N1 for the neutralizing antibodies HC19, CR9114, and BH151 as revealed from the available crystal structures, additional epitopes for these antibodies were also suggested. Moreover, the predicted epitopes of H5N1 HA1 for the newly developed antibody 4F5 are located at the receptor binding domain, while previous study identified a region 76-WLLGNP-81 as the epitope. The possibility of antibody recognition of influenza virus via different mechanism by binding to different epitopes of an antigen is also discussed.
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Bushey RT, Moody MA, Nicely NL, Haynes BF, Alam SM, Keir ST, Bentley RC, Roy Choudhury K, Gottlin EB, Campa MJ, Liao HX, Patz EF. A Therapeutic Antibody for Cancer, Derived from Single Human B Cells. Cell Rep 2016; 15:1505-1513. [PMID: 27160908 DOI: 10.1016/j.celrep.2016.04.038] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 02/17/2016] [Accepted: 04/05/2016] [Indexed: 12/21/2022] Open
Abstract
Some patients with cancer never develop metastasis, and their host response might provide cues for innovative treatment strategies. We previously reported an association between autoantibodies against complement factor H (CFH) and early-stage lung cancer. CFH prevents complement-mediated cytotoxicity (CDC) by inhibiting formation of cell-lytic membrane attack complexes on self-surfaces. In an effort to translate these findings into a biologic therapy for cancer, we isolated and expressed DNA sequences encoding high-affinity human CFH antibodies directly from single, sorted B cells obtained from patients with the antibody. The co-crystal structure of a CFH antibody-target complex shows a conformational change in the target relative to the native structure. This recombinant CFH antibody causes complement activation and release of anaphylatoxins, promotes CDC of tumor cell lines, and inhibits tumor growth in vivo. The isolation of anti-tumor antibodies derived from single human B cells represents an alternative paradigm in antibody drug discovery.
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MESH Headings
- Alanine/genetics
- Animals
- Antibodies, Monoclonal/chemistry
- Antibodies, Monoclonal/genetics
- Antibodies, Monoclonal/therapeutic use
- Autoantibodies/immunology
- B-Lymphocytes/immunology
- Cell Line, Tumor
- Cell Proliferation
- Cloning, Molecular
- Complement Factor H/chemistry
- Complement Factor H/immunology
- Complement System Proteins/immunology
- Crystallography, X-Ray
- Cytotoxicity, Immunologic
- Disease Models, Animal
- Epitopes/immunology
- Gene Rearrangement
- Humans
- Lung Neoplasms/drug therapy
- Lung Neoplasms/pathology
- Mice, Nude
- Models, Molecular
- Mutagenesis/genetics
- Peptides/chemistry
- Peptides/immunology
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Affiliation(s)
- Ryan T Bushey
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
| | - M Anthony Moody
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, NC 27710, USA; Department of Pediatrics, Duke University Medical Center, Durham, NC 27710, USA; Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA
| | - Nathan L Nicely
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, NC 27710, USA
| | - Barton F Haynes
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, NC 27710, USA; Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA; Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA
| | - S Munir Alam
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, NC 27710, USA
| | - Stephen T Keir
- Department of Neurosurgery, Duke University Medical Center, Durham, NC 27710, USA
| | - Rex C Bentley
- Department of Pathology, Duke University Medical Center, Durham, NC 27710, USA
| | - Kingshuk Roy Choudhury
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA; Department of Biostatistics and Bioinformatics, Duke University Medical Center, Durham, NC 27710, USA
| | - Elizabeth B Gottlin
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Michael J Campa
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Hua-Xin Liao
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, NC 27710, USA; Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA.
| | - Edward F Patz
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA; Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA.
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Song H, Xu J, Jin M, Huang C, Bongers J, Bai H, Wu W, Ludwig R, Li Z, Tao L, Das TK. Investigation of Color in a Fusion Protein Using Advanced Analytical Techniques: Delineating Contributions from Oxidation Products and Process Related Impurities. Pharm Res 2015; 33:932-41. [DOI: 10.1007/s11095-015-1839-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 12/02/2015] [Indexed: 02/01/2023]
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Chen W, Li W, Ying T, Wang Y, Feng Y, Dimitrov DS. Germlining of the HIV-1 broadly neutralizing antibody domain m36. Antiviral Res 2015; 116:62-6. [PMID: 25676867 DOI: 10.1016/j.antiviral.2015.02.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Revised: 01/29/2015] [Accepted: 02/02/2015] [Indexed: 12/12/2022]
Abstract
Engineered antibody domains (eAds) have emerged as a novel class of HIV-1 inhibitors and are currently under preclinical testing as promising drug candidates for prevention and therapy of HIV-1 infection. Reverse mutation of antibodies to germline sequences (germlining) could not only identify less mutated variants with lower probability of immunogenicity and other improved properties but also help elucidate their mechanisms of action. In this study, we sequentially reverted the framework (FRs) and complementary determining regions (CDRs) of m36, a human antibody heavy chain variable domain-based eAd targeting the coreceptor binding site of the viral envelope glycoprotein gp120, back to germline sequences. Two types of amino acid mutations and one region in the antibody V segment were identified that are critical for HIV-1 neutralization. These include four mutations to acidic acid residues distributed in the CDR1 and CDR2, two mutations to hydrophobic residues in the FR3 and CDR3, and partial FR2 and FR3 sequences flanking the CDR2 that are derived from a different gene family. An m36 variant with all five mutations in the FRs reverted back to germline showed slightly increased neutralizing activity against two HIV-1 isolates tested. Another variant with seven of twelve mutations in the V segment reverted retained potency within threefold of that of the mature antibody. These results, together with an analysis of m36-gp120-CD4 docking structures, could have implications for the further development of m36 and elucidation of its mechanism of potent and broad HIV-1 neutralization.
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Affiliation(s)
- Weizao Chen
- Protein Interactions Section, Laboratory of Experimental Immunology, Cancer and Inflammation Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD 21702, USA.
| | - Wei Li
- Protein Interactions Section, Laboratory of Experimental Immunology, Cancer and Inflammation Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD 21702, USA
| | - Tianlei Ying
- Protein Interactions Section, Laboratory of Experimental Immunology, Cancer and Inflammation Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD 21702, USA
| | - Yanping Wang
- Protein Interactions Section, Laboratory of Experimental Immunology, Cancer and Inflammation Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD 21702, USA; The Geneva Foundation, WA 98402, USA
| | - Yang Feng
- Protein Interactions Section, Laboratory of Experimental Immunology, Cancer and Inflammation Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD 21702, USA
| | - Dimiter S Dimitrov
- Protein Interactions Section, Laboratory of Experimental Immunology, Cancer and Inflammation Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD 21702, USA
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Malia TJ, Teplyakov A, Brezski RJ, Luo J, Kinder M, Sweet RW, Almagro JC, Jordan RE, Gilliland GL. Structure and specificity of an antibody targeting a proteolytically cleaved IgG hinge. Proteins 2014; 82:1656-67. [PMID: 24638881 DOI: 10.1002/prot.24545] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 02/13/2014] [Accepted: 02/20/2014] [Indexed: 11/09/2022]
Abstract
The functional role of human antihinge (HAH) autoantibodies in normal health and disease remains elusive, but recent evidence supports their role in the host response to IgG cleavage by proteases that are prevalent in certain disorders. Characterization and potential exploitation of these HAH antibodies has been hindered by the absence of monoclonal reagents. 2095-2 is a rabbit monoclonal antibody targeting the IdeS-cleaved hinge of human IgG1. We have determined the crystal structure of the Fab of 2095-2 and its complex with a hinge analog peptide. The antibody is selective for the C-terminally cleaved hinge ending in G236 and this interaction involves an uncommon disulfide in VL CDR3. We probed the importance of the disulfide in VL CDR3 through engineering variants. We identified one variant, QAA, which does not require the disulfide for biological activity or peptide binding. The structure of this variant offers a starting point for further engineering of 2095-2 with the same specificity, but lacking the potential manufacturing liability of an additional disulfide. Proteins 2014; 82:1656-1667. © 2014 Wiley Periodicals, Inc.
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Affiliation(s)
- Thomas J Malia
- Biologics Research, Janssen Research and Development, LLC, Spring House, Pennsylvania
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8
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Shen Y, Zeng L, Zhu A, Blanc T, Patel D, Pennello A, Bari A, Ng S, Persaud K, Kang YK, Balderes P, Surguladze D, Hindi S, Zhou Q, Ludwig DL, Snavely M. Removal of a C-terminal serine residue proximal to the inter-chain disulfide bond of a human IgG1 lambda light chain mediates enhanced antibody stability and antibody dependent cell-mediated cytotoxicity. MAbs 2013; 5:418-31. [PMID: 23567210 PMCID: PMC4169035 DOI: 10.4161/mabs.24291] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Optimization of biophysical properties is a critical success factor for the developability of monoclonal antibodies with potential therapeutic applications. The inter-domain disulfide bond between light chain (Lc) and heavy chain (Hc) in human IgG1 lends structural support for antibody scaffold stability, optimal antigen binding, and normal Fc function. Recently, human IgG1λ has been suggested to exhibit significantly greater susceptibility to reduction of the inter Lc-Hc disulfide bond relative to the same disulfide bond in human IgG1κ. To understand the molecular basis for this observed difference in stability, the sequence and structure of human IgG1λ and human IgG1κ were compared. Based on this Lc comparison, three single mutations were made in the λ Lc proximal to the cysteine residue, which forms a disulfide bond with the Hc. We determined that deletion of S214 (dS) improved resistance of the association between Lc and Hc to thermal stress. In addition, deletion of this terminal serine from the Lc of IgG1λ provided further benefit, including an increase in stability at elevated pH, increased yield from transient transfection, and improved in vitro antibody dependent cell-mediated cytotoxicity (ADCC). These observations support the conclusion that the presence of the terminal serine of the λ Lc creates a weaker inter-chain disulfide bond between the Lc and Hc, leading to slightly reduced stability and a potential compromise in IgG1λ function. Our data from a human IgG1λ provide a basis for further investigation of the effects of deleting terminal serine from λLc on the stability and function of other human IgG1λ antibodies.
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Affiliation(s)
- Yang Shen
- Department of Antibody Technology; ImClone Systems, a wholly-owned subsidiary of Eli Lilly and Company; New York, NY USA
| | - Lin Zeng
- Department of Antibody Technology; ImClone Systems, a wholly-owned subsidiary of Eli Lilly and Company; New York, NY USA
| | - Aiping Zhu
- Department of Antibody Technology; ImClone Systems, a wholly-owned subsidiary of Eli Lilly and Company; New York, NY USA
| | - Tim Blanc
- Department of Bioanalytical Sciences; ImClone Systems, a wholly-owned subsidiary of Eli Lilly and Company; Branchburg, NJ USA
| | - Dipa Patel
- Department of Immunology; ImClone Systems, a wholly-owned subsidiary of Eli Lilly and Company; New York, NY USA
| | - Anthony Pennello
- Department of Oncology Translational Medicine; ImClone Systems, a wholly-owned subsidiary of Eli Lilly and Company; New York, NY USA
| | - Amtul Bari
- Department of BioProcess Sciences; ImClone Systems, a wholly-owned subsidiary of Eli Lilly and Company; New York, NY USA
| | - Stanley Ng
- Department of BioProcess Sciences; ImClone Systems, a wholly-owned subsidiary of Eli Lilly and Company; New York, NY USA
| | - Kris Persaud
- Department of BioProcess Sciences; ImClone Systems, a wholly-owned subsidiary of Eli Lilly and Company; New York, NY USA
| | - Yun Kenneth Kang
- Department of BioProcess Sciences; ImClone Systems, a wholly-owned subsidiary of Eli Lilly and Company; New York, NY USA
| | - Paul Balderes
- Department of BioProcess Sciences; ImClone Systems, a wholly-owned subsidiary of Eli Lilly and Company; New York, NY USA
| | - David Surguladze
- Department of Oncology Translational Medicine; ImClone Systems, a wholly-owned subsidiary of Eli Lilly and Company; New York, NY USA
| | - Sagit Hindi
- Department of BioProcess Sciences; ImClone Systems, a wholly-owned subsidiary of Eli Lilly and Company; New York, NY USA
| | - Qinwei Zhou
- Department of Bioanalytical Sciences; ImClone Systems, a wholly-owned subsidiary of Eli Lilly and Company; Branchburg, NJ USA
| | - Dale L Ludwig
- Department of BioProcess Sciences; ImClone Systems, a wholly-owned subsidiary of Eli Lilly and Company; New York, NY USA
| | - Marshall Snavely
- Department of Antibody Technology; ImClone Systems, a wholly-owned subsidiary of Eli Lilly and Company; New York, NY USA
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9
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Almagro JC, Raghunathan G, Beil E, Janecki DJ, Chen Q, Dinh T, LaCombe A, Connor J, Ware M, Kim PH, Swanson RV, Fransson J. Characterization of a high-affinity human antibody with a disulfide bridge in the third complementarity-determining region of the heavy chain. J Mol Recognit 2012; 25:125-35. [PMID: 22407976 DOI: 10.1002/jmr.1168] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Disulfide bridges are common in the antigen-binding site from sharks (new antigen receptor) and camels (single variable heavy-chain domain, VHH), in which they confer both structural diversity and domain stability. In human antibodies, cysteine residues in the third complementarity-determining region of the heavy chain (CDR-H3) are rare but naturally encoded in the IGHD germline genes. Here, by panning a phage display library designed based on human germline genes and synthetic CDR-H3 regions against a human cytokine, we identified an antibody (M3) containing two cysteine residues in the CDR-H3. It binds the cytokine with high affinity (0.4 nM), recognizes a unique epitope on the antigen, and has a distinct neutralization profile as compared with all other antibodies selected from the library. The two cysteine residues form a disulfide bridge as determined by mass spectrometric peptide mapping. Replacing the cysteines with alanines did not change the solubility and stability of the monoclonal antibody, but binding to the antigen was significantly impaired. Three-dimensional modeling and dynamic simulations were employed to explore how the disulfide bridge influences the conformation of CDR-H3 and binding to the antigen. On the basis of these results, we envision that designing human combinatorial antibody libraries to contain intra-CDR or inter-CDR disulfide bridges could lead to identification of human antibodies with unique binding profiles.
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