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Liang S, Zhang C. Prediction of immunogenicity for humanized and full human therapeutic antibodies. PLoS One 2020; 15:e0238150. [PMID: 32866159 PMCID: PMC7458303 DOI: 10.1371/journal.pone.0238150] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 08/10/2020] [Indexed: 01/02/2023] Open
Abstract
Immunogenicity is an important concern for therapeutic antibodies during drug development. By analyzing co-crystal structures of idiotypic antibodies and their antibodies, we found that anti-idiotypic antibodies usually bind the Complementarity Determining Regions (CDR) of idiotypic antibodies. Sequence and structural features were identified for distinguishing immunogenic antibodies from non-immunogenic antibodies. For example, non-immunogenic antibodies have a significantly larger cavity volume at the CDR region and a more hydrophobic CDR-H3 loop than immunogenic antibodies. Antibodies containing no Gly at the turn of CDR-H2 loop are often immunogenic. We integrated these features together with a machine learning platform to Predict Immunogenicity for humanized and full human THerapeutic Antibodies (PITHA). This method achieved an accuracy of 83% in leave-one-out experiment for 29 therapeutic antibodies with available crystal structures. The accuracy decreased to 65% for 23 test antibodies with modeled structures, because their crystal structures were not available, and the prediction was made with modeled structures. The server of this method is accessible at http://mabmedicine.com/PITHA.
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Affiliation(s)
- Shide Liang
- Department of Research and Development, Bio-Thera Solutions, Guangzhou, P. R. China
- * E-mail: (SL); (CZ)
| | - Chi Zhang
- School of Biological Sciences, University of Nebraska, Lincoln, NE, United States of America
- * E-mail: (SL); (CZ)
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Gorovits B, Peng K, Kromminga A. Current Considerations on Characterization of Immune Response to Multi-Domain Biotherapeutics. BioDrugs 2019; 34:39-54. [DOI: 10.1007/s40259-019-00389-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Fluorescence-guided tumor detection with a novel anti-EpCAM targeted antibody fragment: Preclinical validation. Surg Oncol 2018; 28:1-8. [PMID: 30851880 DOI: 10.1016/j.suronc.2018.10.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 09/13/2018] [Accepted: 10/08/2018] [Indexed: 12/22/2022]
Abstract
Tumor-specific fluorescent imaging agents are moving towards the clinic, supporting surgeons with real-time intraoperative feedback about tumor locations. The epithelial cell adhesion molecule (EpCAM) is considered as one of the most promising tumor-specific proteins due its high overexpression on epithelial-derived cancers. This study describes the development and evaluation of EpCAM-F800, a novel fluorescent anti-EpCAM antibody fragment, for intraoperative tumor imaging. Fab production, conjugation to the fluorophore IRDye 800CW, and binding capacities were determined and validated using HPLC, spectrophotometry and cell-based assays. In vivo, dose escalation-, blocking-, pharmacokinetic- and biodistribution studies (using both fluorescence and radioactivity) were performed, next to imaging of clinically relevant orthotopic xenografts for breast and colorectal cancer. EpCAM-F800 targets EpCAM with high specificity in vitro, which was validated using in vivo blocking experiments with a 10x higher dose of unlabeled Fab. The optimal dose range for fluorescence tumor detection in mice was 1-5 nmol (52-260 μg), which corresponds to a human equivalent dose of 0.2-0.8 mg/kg. Biodistribution showed high accumulation of EpCAM-F800 in tumors and metabolizing organs. Breast and colorectal tumors could clearly be visualized within 8 h post-injection and up to 96 h, while the agent already showed homogenous tumor distribution within 4 h. The blood half-life was 4.5 h. This study describes the development and evaluation of a novel EpCAM-targeting agent and the feasibility to visualize breast and colorectal tumors by fluorescence imaging during resections. EpCAM-F800 will be translated for clinical use, considering its abundance in a broad range of tumor types.
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Bortolotti M, Bolognesi A, Polito L. Bouganin, an Attractive Weapon for Immunotoxins. Toxins (Basel) 2018; 10:E323. [PMID: 30096764 PMCID: PMC6115712 DOI: 10.3390/toxins10080323] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 07/27/2018] [Accepted: 08/02/2018] [Indexed: 11/23/2022] Open
Abstract
Bougainvillea (Bougainvillea spectabilis Willd.) is a plant widely used in folk medicine and many extracts from different tissues of this plant have been employed against several pathologies. The observation that leaf extracts of Bougainvillea possess antiviral properties led to the purification and characterization of a protein, named bouganin, which exhibits typical characteristics of type 1 ribosome-inactivating proteins (RIPs). Beyond that, bouganin has some peculiarities, such as a higher activity on DNA with respect to ribosomal RNA, low systemic toxicity, and immunological properties quite different than other RIPs. The sequencing of bouganin and the knowledge of its three-dimensional structure allowed to obtain a not immunogenic mutant of bouganin. These features make bouganin a very attractive tool as a component of immunotoxins (ITs), chimeric proteins obtained by linking a toxin to a carrier molecule. Bouganin-containing ITs showed very promising results in the experimental treatment of both hematological and solid tumors, and one bouganin-containing IT has entered Phase I clinical trial. In this review, we summarize the milestones of the research on bouganin such as bouganin chemico-physical characteristics, the structural properties and de-immunization studies. In addition, the in vitro and in vivo results obtained with bouganin-containing ITs are summarized.
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Affiliation(s)
- Massimo Bortolotti
- Department of Experimental, Diagnostic and Specialty Medicine-DIMES, General Pathology Section, Alma Mater Studiorum-University of Bologna, Via S. Giacomo 14, 40126 Bologna, Italy.
| | - Andrea Bolognesi
- Department of Experimental, Diagnostic and Specialty Medicine-DIMES, General Pathology Section, Alma Mater Studiorum-University of Bologna, Via S. Giacomo 14, 40126 Bologna, Italy.
| | - Letizia Polito
- Department of Experimental, Diagnostic and Specialty Medicine-DIMES, General Pathology Section, Alma Mater Studiorum-University of Bologna, Via S. Giacomo 14, 40126 Bologna, Italy.
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The Use of Plant-Derived Ribosome Inactivating Proteins in Immunotoxin Development: Past, Present and Future Generations. Toxins (Basel) 2017; 9:toxins9110344. [PMID: 29076988 PMCID: PMC5705959 DOI: 10.3390/toxins9110344] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 10/20/2017] [Accepted: 10/24/2017] [Indexed: 12/20/2022] Open
Abstract
Ribosome inactivating proteins (RIPs) form a class of toxins that was identified over a century ago. They continue to fascinate scientists and the public due to their very high activity and long-term stability which might find useful applications in the therapeutic killing of unwanted cells but can also be used in acts of terror. We will focus our review on the canonical plant-derived RIPs which display ribosomal RNA N-glycosidase activity and irreversibly inhibit protein synthesis by cleaving the 28S ribosomal RNA of the large 60S subunit of eukaryotic ribosomes. We will place particular emphasis on therapeutic applications and the generation of immunotoxins by coupling antibodies to RIPs in an attempt to target specific cells. Several generations of immunotoxins have been developed and we will review their optimisation as well as their use and limitations in pre-clinical and clinical trials. Finally, we endeavour to provide a perspective on potential future developments for the therapeutic use of immunotoxins.
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Addressing the Immunogenicity of the Cargo and of the Targeting Antibodies with a Focus on Demmunized Bacterial Toxins and on Antibody-Targeted Human Effector Proteins. Biomedicines 2017; 5:biomedicines5020028. [PMID: 28574434 PMCID: PMC5489814 DOI: 10.3390/biomedicines5020028] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Revised: 05/23/2017] [Accepted: 05/31/2017] [Indexed: 12/22/2022] Open
Abstract
Third-generation immunotoxins are composed of a human, or humanized, targeting moiety, usually a monoclonal antibody or an antibody fragment, and a non-human effector molecule. Due to the non-human origin of the cytotoxic domain, these molecules stimulate potent anti-drug immune responses, which limit treatment options. Efforts are made to deimmunize such immunotoxins or to combine treatment with immunosuppression. An alternative approach is using the so-called “human cytotoxic fusion proteins”, in which antibodies are used to target human effector proteins. Here, we present three relevant approaches for reducing the immunogenicity of antibody-targeted protein therapeutics: (1) reducing the immunogenicity of the bacterial toxin, (2) fusing human cytokines to antibodies to generate immunocytokines and (3) addressing the immunogenicity of the targeting antibodies.
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Kang HJ, Kim HJ, Jung MS, Han JK, Cha SH. Optimal expression of a Fab-effector fusion protein in Escherichia coli by removing the cysteine residues responsible for an interchain disulfide bond of a Fab molecule. Immunol Lett 2017; 184:34-42. [DOI: 10.1016/j.imlet.2017.02.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Revised: 02/09/2017] [Accepted: 02/13/2017] [Indexed: 10/20/2022]
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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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Boonstra MC, de Geus SWL, Prevoo HAJM, Hawinkels LJAC, van de Velde CJH, Kuppen PJK, Vahrmeijer AL, Sier CFM. Selecting Targets for Tumor Imaging: An Overview of Cancer-Associated Membrane Proteins. BIOMARKERS IN CANCER 2016; 8:119-133. [PMID: 27721658 PMCID: PMC5040425 DOI: 10.4137/bic.s38542] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 09/05/2016] [Accepted: 09/06/2016] [Indexed: 12/30/2022]
Abstract
Tumor targeting is a booming business: The global therapeutic monoclonal antibody market accounted for more than $78 billion in 2012 and is expanding exponentially. Tumors can be targeted with an extensive arsenal of monoclonal antibodies, ligand proteins, peptides, RNAs, and small molecules. In addition to therapeutic targeting, some of these compounds can also be applied for tumor visualization before or during surgery, after conjugation with radionuclides and/or near-infrared fluorescent dyes. The majority of these tumor-targeting compounds are directed against cell membrane-bound proteins. Various categories of targetable membrane-bound proteins, such as anchoring proteins, receptors, enzymes, and transporter proteins, exist. The functions and biological characteristics of these proteins determine their location and distribution on the cell membrane, making them more, or less, accessible, and therefore, it is important to understand these features. In this review, we evaluate the characteristics of cancer-associated membrane proteins and discuss their overall usability for cancer targeting, especially focusing on imaging applications.
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Affiliation(s)
- Martin C Boonstra
- Department of Surgery, Leiden University Medical Center, Leiden, the Netherlands
| | - Susanna W L de Geus
- Department of Surgery, Leiden University Medical Center, Leiden, the Netherlands
| | | | - Lukas J A C Hawinkels
- Department of Gastroenterology, Leiden University Medical Center, Leiden, the Netherlands
| | | | - Peter J K Kuppen
- Department of Surgery, Leiden University Medical Center, Leiden, the Netherlands.; Antibodies for Research Applications BV, Gouda, the Netherlands
| | | | - Cornelis F M Sier
- Department of Surgery, Leiden University Medical Center, Leiden, the Netherlands.; Antibodies for Research Applications BV, Gouda, the Netherlands
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Bruce VJ, Ta AN, McNaughton BR. Minimalist Antibodies and Mimetics: An Update and Recent Applications. Chembiochem 2016; 17:1892-1899. [DOI: 10.1002/cbic.201600303] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Indexed: 12/14/2022]
Affiliation(s)
- Virginia J. Bruce
- Department of Chemistry; Colorado State University; Fort Collins CO 80523 USA
| | - Angeline N. Ta
- Department of Chemistry; Colorado State University; Fort Collins CO 80523 USA
| | - Brian R. McNaughton
- Department of Chemistry; Colorado State University; Fort Collins CO 80523 USA
- Department of Biochemistry and Molecular Biology; Colorado State University; Fort Collins CO 80523 USA
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Zhao H, Verma D, Li W, Choi Y, Ndong C, Fiering SN, Bailey-Kellogg C, Griswold KE. Depletion of T cell epitopes in lysostaphin mitigates anti-drug antibody response and enhances antibacterial efficacy in vivo. ACTA ACUST UNITED AC 2016; 22:629-39. [PMID: 26000749 DOI: 10.1016/j.chembiol.2015.04.017] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Revised: 04/16/2015] [Accepted: 04/17/2015] [Indexed: 01/17/2023]
Abstract
The enzyme lysostaphin possesses potent anti-staphylococcal activity and represents a promising antibacterial drug candidate; however, its immunogenicity poses a barrier to clinical translation. Here, structure-based biomolecular design enabled widespread depletion of lysostaphin DRB1(∗)0401 restricted T cell epitopes, and resulting deimmunized variants exhibited striking reductions in anti-drug antibody responses upon administration to humanized HLA-transgenic mice. This reduced immunogenicity translated into improved efficacy in the form of protection against repeated challenges with methicillin-resistant Staphylococcus aureus (MRSA). In contrast, while wild-type lysostaphin was efficacious against the initial MRSA infection, it failed to clear subsequent bacterial challenges that were coincident with escalating anti-drug antibody titers. These results extend the existing deimmunization literature, in which reduced immunogenicity and retained efficacy are assessed independently of each other. By correlating in vivo efficacy with longitudinal measures of anti-drug antibody development, we provide the first direct evidence that T cell epitope depletion manifests enhanced biotherapeutic efficacy.
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Affiliation(s)
- Hongliang Zhao
- Thayer School of Engineering at Dartmouth, 14 Engineering Drive, Hanover, NH 03755, USA; Laboratory of Microorganism Engineering, Beijing Institute of Biotechnology, 20 Dongdajie Street, Fengtai District, Beijing 100071, People's Republic of China
| | - Deeptak Verma
- Department of Computer Science, Dartmouth, 6211 Sudikoff Laboratory, Hanover, NH 03755, USA
| | - Wen Li
- Thayer School of Engineering at Dartmouth, 14 Engineering Drive, Hanover, NH 03755, USA
| | - Yoonjoo Choi
- Department of Computer Science, Dartmouth, 6211 Sudikoff Laboratory, Hanover, NH 03755, USA
| | - Christian Ndong
- Thayer School of Engineering at Dartmouth, 14 Engineering Drive, Hanover, NH 03755, USA
| | - Steven N Fiering
- Department of Microbiology and Immunology, Dartmouth, Hanover, NH 03755, USA; Norris Cotton Cancer Center at Dartmouth, Lebanon, NH 03766, USA
| | - Chris Bailey-Kellogg
- Department of Computer Science, Dartmouth, 6211 Sudikoff Laboratory, Hanover, NH 03755, USA.
| | - Karl E Griswold
- Thayer School of Engineering at Dartmouth, 14 Engineering Drive, Hanover, NH 03755, USA; Norris Cotton Cancer Center at Dartmouth, Lebanon, NH 03766, USA; Department of Biological Sciences, Dartmouth, Hanover, NH 03755, USA.
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Kang HJ, Kim HJ, Cha SH. Isolation of human anti-serum albumin Fab antibodies with an extended serum-half life. Immunol Lett 2016; 169:33-40. [DOI: 10.1016/j.imlet.2015.11.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 11/18/2015] [Accepted: 11/18/2015] [Indexed: 10/22/2022]
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Alewine C, Hassan R, Pastan I. Advances in anticancer immunotoxin therapy. Oncologist 2015; 20:176-85. [PMID: 25561510 PMCID: PMC4319635 DOI: 10.1634/theoncologist.2014-0358] [Citation(s) in RCA: 140] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 11/25/2014] [Indexed: 12/26/2022] Open
Abstract
Immunotoxins are a novel class of antibody-conjugated therapeutics currently in clinical development for a variety of malignancies. They consist of an antibody-based targeting domain fused to a bacterial toxin payload for cell killing. Immunotoxins kill cells by inhibiting protein synthesis, a unique mechanism of action that is toxic to both dividing and nondividing cells. Recent advances in the design and administration of immunotoxins are overcoming historical challenges in the field, leading to renewed interest in these therapeutics.
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Affiliation(s)
- Christine Alewine
- Laboratory of Molecular Biology and Thoracic and Gastrointestinal Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Raffit Hassan
- Laboratory of Molecular Biology and Thoracic and Gastrointestinal Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Ira Pastan
- Laboratory of Molecular Biology and Thoracic and Gastrointestinal Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
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Rybalov M, Ananias HJK, Hoving HD, van der Poel HG, Rosati S, de Jong IJ. PSMA, EpCAM, VEGF and GRPR as imaging targets in locally recurrent prostate cancer after radiotherapy. Int J Mol Sci 2014; 15:6046-61. [PMID: 24727373 PMCID: PMC4013614 DOI: 10.3390/ijms15046046] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 03/28/2014] [Accepted: 03/28/2014] [Indexed: 12/31/2022] Open
Abstract
In this retrospective pilot study, the expression of the prostate-specific membrane antigen (PSMA), the epithelial cell adhesion molecule (EpCAM), the vascular endothelial growth factor (VEGF) and the gastrin-releasing peptide receptor (GRPR) in locally recurrent prostate cancer after brachytherapy or external beam radiotherapy (EBRT) was investigated, and their adequacy for targeted imaging was analyzed. Prostate cancer specimens were collected of 17 patients who underwent salvage prostatectomy because of locally recurrent prostate cancer after brachytherapy or EBRT. Immunohistochemistry was performed. A pathologist scored the immunoreactivity in prostate cancer and stroma. Staining for PSMA was seen in 100% (17/17), EpCAM in 82.3% (14/17), VEGF in 82.3% (14/17) and GRPR in 100% (17/17) of prostate cancer specimens. Staining for PSMA, EpCAM and VEGF was seen in 0% (0/17) and for GRPR in 100% (17/17) of the specimens’ stromal compartments. In 11.8% (2/17) of cases, the GRPR staining intensity of prostate cancer was higher than stroma, while in 88.2% (15/17), the staining was equal. Based on the absence of stromal staining, PSMA, EpCAM and VEGF show high tumor distinctiveness. Therefore, PSMA, EpCAM and VEGF can be used as targets for the bioimaging of recurrent prostate cancer after EBRT to exclude metastatic disease and/or to plan local salvage therapy.
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Affiliation(s)
- Maxim Rybalov
- Department of Urology, University Medical Center Groningen, University of Groningen, P.O. Box 30.001, Groningen 9700 RB NL, The Netherlands.
| | - Hildo J K Ananias
- Department of Urology, University Medical Center Groningen, University of Groningen, P.O. Box 30.001, Groningen 9700 RB NL, The Netherlands.
| | - Hilde D Hoving
- Department of Urology, University Medical Center Groningen, University of Groningen, P.O. Box 30.001, Groningen 9700 RB NL, The Netherlands.
| | - Henk G van der Poel
- Department of Urology, the Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Plesmanlaan 121, Amsterdam 1066 CX, The Netherlands.
| | - Stefano Rosati
- Department of Pathology, University Medical Center Groningen, University of Groningen, P.O. Box 30.001, Groningen 9700 RB NL, The Netherlands.
| | - Igle J de Jong
- Department of Urology, University Medical Center Groningen, University of Groningen, P.O. Box 30.001, Groningen 9700 RB NL, The Netherlands.
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Mohamedali KA, Cao Y, Cheung LH, Hittelman WN, Rosenblum MG. The functionalized human serine protease granzyme B/VEGF₁₂₁ targets tumor vasculature and ablates tumor growth. Mol Cancer Ther 2013; 12:2055-66. [PMID: 23858102 DOI: 10.1158/1535-7163.mct-13-0165] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The serine protease granzyme B (GrB) induces apoptosis through both caspase-dependent and -independent multiple-cascade mechanisms. VEGF₁₂₁ binds to both VEGF receptor (VEGFR)-1 and VEGFR-2 receptors. We engineered a unique GrB/VEGF₁₂₁ fusion protein and characterized its properties in vitro and in vivo. Endothelial and tumor cell lines showed varying levels of sensitivity to GrB/VEGF₁₂₁ that correlated closely to total VEGFR-2 expression. GrB/VEGF₁₂₁ localized efficiently into VEGFR-2-expressing cells, whereas the internalization into VEGFR-1-expressing cells was significantly reduced. Treatment of VEGFR-2(+) cells caused mitochondrial depolarization in 48% of cells by 48 hours. Exposure to GrB/VEGF₁₂₁ induced apoptosis in VEGFR-2(+), but not in VEGFR-1(+), cells and rapid caspase activation was observed that could not be inhibited by treatment with a pan-caspase inhibitor. In vivo, GrB/VEGF₁₂₁ localized in perivascular tumor areas adjacent to microvessels and in other areas in the tumor less well vascularized, whereas free GrB did not specifically localize to tumor tissue. Administration (intravenous) of GrB/VEGF₁₂₁ to mice at doses up to 40 mg/kg showed no toxicity. Treatment of mice bearing established PC-3 tumor xenografts with GrB/VEGF₁₂₁ showed significant antitumor effect versus treatment with GrB or saline. Treatment with GrB/VEGF₁₂₁ at 27 mg/kg resulted in the regression of four of five tumors in this group. Tumors showed a two-fold lower Ki-67-labeling index compared with controls. Our results show that targeted delivery of GrB to tumor vascular endothelial cells or to tumor cells activates apoptotic cascades and this completely human construct may have significant therapeutic potential.
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Affiliation(s)
- Khalid A Mohamedali
- Corresponding Author: Michael G. Rosenblum, Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Unit 1950, 1515 Holcombe Blvd., Houston, TX 77030.
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Ribosome-inactivating proteins: from toxins to useful proteins. Toxicon 2013; 67:12-6. [PMID: 23462379 DOI: 10.1016/j.toxicon.2013.02.005] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 01/22/2013] [Accepted: 02/07/2013] [Indexed: 01/08/2023]
Abstract
Ribosome-inactivating proteins (RIPs) either single-chain (type 1) or two-chain (type 2) are frequent in plants, often in multiple forms. They are RNA N-glycosidases, have antiviral, antifungal and insecticidal activity. Their expression in plants is increased under stressful conditions. They are investigated for practical applications in medicine and in agriculture. In medicine, RIPs have been linked to, or fused with, appropriate antibodies or other carriers to form "immunotoxins" or other conjugates specifically toxic to the cells target of the carrier, with the aim of eliminating malignant or other undesired cells. In agriculture, it has been observed that an enhanced expression of RIPs confers to plants an increased resistance to viruses, fungi, insects, and also to drought and salinity.
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An Old Idea Tackling a New Problem: Targeted Toxins Specific for Cancer Stem Cells. Antibodies (Basel) 2013. [DOI: 10.3390/antib2010082] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
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Simon M, Stefan N, Plückthun A, Zangemeister-Wittke U. Epithelial cell adhesion molecule-targeted drug delivery for cancer therapy. Expert Opin Drug Deliv 2013; 10:451-68. [PMID: 23316711 DOI: 10.1517/17425247.2013.759938] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
INTRODUCTION The epithelial cell adhesion molecule (EpCAM) is abundantly expressed in epithelial tumors, on cancer stem cells and circulating tumor cells. Together with its role in oncogenic signaling, this has sparked interest in its potential for tumor targeting with antibodies and drug conjugates for safe and effective cancer therapy. Recent advances in protein engineering, linker design and drug formulations have provided a multitude of EpCAM-targeting anticancer agents, several of them with good perspectives for clinical development. AREAS COVERED This article reviews the biological, therapeutic and technical aspects of EpCAM-targeted drug delivery for cancer therapy. The authors discuss seminal findings, which distinguish EpCAM as a target with oncogenic function and abundant expression in epithelial tumors. Moreover, recent trends in engineering improved anti-EpCAM antibodies, binding proteins that are not derived from immunoglobulins and drug conjugates derived from them are highlighted and their therapeutic potential based on reported preclinical and clinical data, originality of design and perspectives are critically assessed. EXPERT OPINION EpCAM has shown promise for safe and efficient targeting of solid tumors using antibodies, alternative binding molecules and novel drug conjugates. Among the myriad of EpCAM-targeting drug delivery systems investigated so far, several could demonstrate therapeutic benefit, other formulations engineered to become tailor-made missiles are on the brink.
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Affiliation(s)
- Manuel Simon
- University of Bern, Institute of Pharmacology, Friedbühlstrasse 49, CH-3010 Bern, Switzerland
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