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Sharma R, Mukherjee A, Kumar A, Sarma HD. Evaluation of 177Lu-Labeled Pertuzumab F(ab') 2 Fragments for HER2-Positive Cancer Targeting: A Comparative In Vitro and In Vivo Study. Cancer Biother Radiopharm 2024; 39:64-74. [PMID: 38363819 DOI: 10.1089/cbr.2023.0108] [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] [Indexed: 02/18/2024] Open
Abstract
Background: Radiolabeled antibody fragments present a promising opportunity as theranostic agents, offering distinct advantages over whole antibodies. In this study, the authors investigate the potential of [177Lu]Lu-DTPA-F(ab')2-pertuzumab as a theranostic agent for precise targeting of human epidermal growth factor receptor 2 (HER2)-positive cancers. Additionally, the authors aim to quantitatively assess the binding synergism in the presence of cold trastuzumab. Materials and Methods: F(ab')2-pertuzumab was prepared by pepsin digestion and conjugated with a bifunctional chelator. The immunoconjugate was radiolabeled with 177Lu and characterized by chromatography techniques. Binding parameters (affinity, specificity, and immunoreactivity) and cellular binding enhancement studies were evaluated in HER2-overexpressing and triple-negative cell lines. The in vivo enhancement in tumor uptake of the radiolabeled immunoformulation was assessed in severe combined immunodeficient (SCID) mice bearing tumors, both in the presence and absence of unlabeled trastuzumab. Results: The formulation of [177Lu]Lu-DTPA-F(ab')2-pertuzumab could be prepared in high yields and with consistent radiochemical purity, ensuring reproducibility. Comprehensive in vitro and in vivo evaluation studies confirmed high specificity and immunoreactivity of the formulation toward HER2 receptors. Binding synergism of radiolabeled pertuzumab fragments in the presence of trastuzumab to HER2 receptors was observed. Conclusions: The radioformulation of [177Lu]Lu-DTPA-F(ab')2-pertuzumab holds great promise as a targeted approach for addressing HER2-positive cancers. A potentially effective strategy to amplify therapeutic efficacy involves dual epitope targeting by combining radiolabeled pertuzumab with cold trastuzumab.
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Affiliation(s)
- Rohit Sharma
- Radiopharmaceuticals Division, Bhabha Atomic Research Centre (BARC), Mumbai, India
- Department of Life Sciences, Homi Bhabha National Institute, Mumbai, India
| | - Archana Mukherjee
- Radiopharmaceuticals Division, Bhabha Atomic Research Centre (BARC), Mumbai, India
- Department of Life Sciences, Homi Bhabha National Institute, Mumbai, India
| | - Anuj Kumar
- Radiopharmaceuticals Division, Bhabha Atomic Research Centre (BARC), Mumbai, India
| | - Haladhar Dev Sarma
- Radiation Biology & Health Sciences Division, Bhabha Atomic Research Centre (BARC), Mumbai, India
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Ghosh S, Fletcher NL, Huda P, Houston ZH, Howard CB, Lund ME, Lu Y, Campbell DH, Walsh BJ, Thurecht KJ. Pharmacokinetics and Biodistribution of 89Zr-Miltuximab and Its Antibody Fragments as Glypican-1 Targeting Immuno-PET Agents in Glioblastoma. Mol Pharm 2023; 20:1549-1563. [PMID: 36602058 DOI: 10.1021/acs.molpharmaceut.2c00760] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Glioblastoma (GBM) is the most aggressive form of primary brain cancer, accounting for about 85% of all primary central nervous system (CNS) tumors. With standard treatment strategies like surgery, radiation, and chemotherapy, the median survival time of patients with GBM is only 12-15 months from diagnosis. The poor prognosis of GBM is due to a very high tumor recurrence rate following initial treatment, indicating a dire need for improved diagnostic and therapeutic alternatives for this disease. Antibody-based immunotheranostics holds great promise in treating GBM, combining the theranostic applications of radioisotopes and target-specificity of antibodies. In this study, we developed and validated antibody-based positron emission tomography (PET) tracers targeting the heparan sulfate proteoglycan, glypican-1 (GPC-1), for noninvasive detection of disease using diagnostic molecular imaging. GPC-1 is overexpressed in multiple solid tumor types, including GBM, and is a promising biomarker for novel immunotheranostics. Here, we investigate zirconium-89 (89Zr)-conjugated Miltuximab (a clinical stage anti-GPC-1 monoclonal antibody developed by GlyTherix, Ltd.) and engineered fragments for their potential as immuno-PET tracers to detect GPC-1positive GBM tumors in preclinical models. We explore the effects of molecular size, avidity, and Fc-domain on the pharmacokinetics and biodistribution in vivo, by comparing in parallel the full-length antibody (Miltuximab), Fab'2, Fab, and single-chain variable fragment (scFv) formats. High radiolabeling efficiency (>95%) was demonstrated by all the formats and the stability post-radiolabeling was higher for larger constructs of Miltuximab and the Fab. Receptor-mediated internalization of all 89Zr-labeled formats was observed in a human GBM cell line in vitro, while full-length Miltuximab demonstrated the highest tumor retention (5.7 ± 0.94% ID/g, day-9 postinjection (p.i.)) and overall better tumor-to-background ratios than the smaller Fc-less formats. Results from in vivo PET image quantification and ex vivo scintillation counting were highly correlated. Altogether, 89Zr-DFO-Miltuximab appears to be an effective immuno-PET imaging agent for detecting GPC-1positive tumors such as GBM and the current results support utility of the Fc containing whole mAb format over smaller antibody fragments for this target.
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Affiliation(s)
- Saikat Ghosh
- Centre for Advanced Imaging (CAI), Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, Queensland4072, Australia.,ARC Training Centre for Innovation in Biomedical Imaging Technology (CIBIT), The University of Queensland, Brisbane, Queensland4072, Australia
| | - Nicholas L Fletcher
- Centre for Advanced Imaging (CAI), Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, Queensland4072, Australia
| | - Pie Huda
- Centre for Advanced Imaging (CAI), Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, Queensland4072, Australia
| | - Zachary H Houston
- Centre for Advanced Imaging (CAI), Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, Queensland4072, Australia
| | - Christopher B Howard
- Centre for Advanced Imaging (CAI), Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, Queensland4072, Australia
| | - Maria E Lund
- GlyTherix Ltd, Ground Floor, 75 Talavera Road, Macquarie Park, New South Wales2113, Australia
| | - Yanling Lu
- GlyTherix Ltd, Ground Floor, 75 Talavera Road, Macquarie Park, New South Wales2113, Australia
| | - Douglas H Campbell
- GlyTherix Ltd, Ground Floor, 75 Talavera Road, Macquarie Park, New South Wales2113, Australia
| | - Bradley J Walsh
- GlyTherix Ltd, Ground Floor, 75 Talavera Road, Macquarie Park, New South Wales2113, Australia
| | - Kristofer J Thurecht
- Centre for Advanced Imaging (CAI), Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, Queensland4072, Australia.,ARC Training Centre for Innovation in Biomedical Imaging Technology (CIBIT), The University of Queensland, Brisbane, Queensland4072, Australia
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Javan Nikkhah S, Cazade PA, McManus JJ, Thompson D. Design Rules for Antibody Delivery by Self-Assembled Block-Copolyelectrolyte Nanocapsules. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c00118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Sousa Javan Nikkhah
- Department of Physics, Bernal Institute, University of Limerick, V94 T9PX Limerick, Ireland
| | - Pierre A. Cazade
- Department of Physics, Bernal Institute, University of Limerick, V94 T9PX Limerick, Ireland
| | - Jennifer J. McManus
- H. H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, United Kingdom
| | - Damien Thompson
- Department of Physics, Bernal Institute, University of Limerick, V94 T9PX Limerick, Ireland
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Sharma R, Kameswaran M, Dash A. Comparative In Vitro Cytotoxicity Studies of 177Lu-CHX-A″-DTPA-Trastuzumab and 177Lu-CHX-A″-DTPA-F(ab') 2-Trastuzumab in HER2-Positive Cancer Cell Lines. Cancer Biother Radiopharm 2020; 35:177-189. [PMID: 32196365 DOI: 10.1089/cbr.2019.2882] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Background: Human epidermal growth factor receptor 2 (HER2) is found to be amplified in ∼15%-20% of breast cancers. In this study, the authors report the synthesis and comparative in vitro therapeutic efficacy of 177Lu-CHX-A″-DTPA-trastuzumab and 177Lu-CHX-A″-DTPA-F(ab')2-trastuzumab to determine their potential as theranostic agents for patients with breast cancer. Materials and Methods: Bivalent F(ab')2-trastuzumab was produced by enzymatic digestion of trastuzumab, conjugated with p-SCN-Bn-CHX-A″-DTPA and subsequently radiolabeled with 177Lu. Cell viability, membrane toxicity assays, and apoptosis analysis were carried out with 177Lu-CHX-A″-DTPA-trastuzumab and 177Lu-CHX-A″-DTPA-F(ab')2-trastuzumab in HER2-positive ovarian (SK-OV-3) and breast cancer (SK-BR-3 and MDA-MB-453) cells. Results: In vitro cell binding studies showed ∼20%-25% binding of 177Lu-CHX-A″-DTPA-trastuzumab and 177Lu-CHX-A″-DTPA-F(ab')2-trastuzumab to SK-OV-3, SK-BR-3, and MDA-MB-453 cells. The cells exhibited similar degree of membrane integrity and cellular toxicity when treated with same amount (activity) of 177Lu-CHX-A″-DTPA-F(ab')2-trastuzumab and 177Lu-CHX-A″-DTPA-trastuzumab, and the toxicity was dose dependent. The mode of cell death was predominantly by apoptosis and necrosis with both the radioimmunoconjugates. Conclusions: The results indicated that the efficacy of both the radioimmunoconjugates, in terms of inducing cell death, was similar thereby ascertaining their potential as good therapeutic agents for patients with breast cancer.
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Affiliation(s)
- Rohit Sharma
- Radiopharmaceuticals Division, Bhabha Atomic Research Centre, Mumbai, India
| | - Mythili Kameswaran
- Radiopharmaceuticals Division, Bhabha Atomic Research Centre, Mumbai, India
| | - Ashutosh Dash
- Radiopharmaceuticals Division, Bhabha Atomic Research Centre, Mumbai, India.,Homi Bhabha National Institute, Mumbai, India
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Hermanto S, Haryuni RD, Ramli M, Mutalib A, Hudiyono S. Synthesis and stability test of radioimmunoconjugate 177Lu-DOTA-F(ab′)2-trastuzumab for theranostic agent of HER2 positive breast cancer. JOURNAL OF RADIATION RESEARCH AND APPLIED SCIENCES 2019. [DOI: 10.1016/j.jrras.2016.07.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Sandra Hermanto
- Department of Chemistry, Faculty of Mathematics and Science, University of Indonesia, Depok, 16424, Indonesia
- Study Program of Chemistry, Faculty of Science and Technology, Syarif Hidayatullah State Islamic University, Jl. Ir, H. Juanda No. 95, Ciputat, Jakarta, 15412, Indonesia
| | - Ratna Dini Haryuni
- Centre for Radioisotopes and Radiopharmaceuticals, National Nuclear Energy Agency of Indonesia, Kawasan Puspiptek, Setu, Kota Tangerang Selatan, Banten, 15314, Indonesia
| | - Martalena Ramli
- Centre for Radioisotopes and Radiopharmaceuticals, National Nuclear Energy Agency of Indonesia, Kawasan Puspiptek, Setu, Kota Tangerang Selatan, Banten, 15314, Indonesia
| | - Abdul Mutalib
- Department of Chemistry, Faculty of Mathematics and Science, Padjadjaran University, Jl. Raya Bandung-Sumedang Km. 21, Jatinangor, Jawa Barat, Indonesia
| | - Sumi Hudiyono
- Department of Chemistry, Faculty of Mathematics and Science, University of Indonesia, Depok, 16424, Indonesia
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Klaus T, Bereta J. CH2 Domain of Mouse IgG3 Governs Antibody Oligomerization, Increases Functional Affinity to Multivalent Antigens and Enhances Hemagglutination. Front Immunol 2018; 9:1096. [PMID: 29875771 PMCID: PMC5974032 DOI: 10.3389/fimmu.2018.01096] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 05/02/2018] [Indexed: 01/06/2023] Open
Abstract
Mouse IgG3 is highly protective against several life-threatening bacteria. This isotype is the only one among mouse IgGs that forms non-covalent oligomers, has increased functional affinity to polyvalent antigens, and efficiently agglutinates erythrocytes. IgG3 also triggers the complement cascade. The high efficacy of protection after passive immunization with IgG3 is correlated with the unique properties of this isotype. Although the features of IgG3 are well documented, their molecular basis remains elusive. Based on functional analyses of IgG1/IgG3 hybrid molecules with swapped constant domains, we identified IgG3-derived CH2 domain as a major determinant of antibody oligomerization and increased functional affinity to a multivalent antigen. The CH2 domain was also crucial for efficient hemagglutination triggered by IgG3 and was indispensable for complement cascade activation. This domain is glycosylated and atypically charged. A mutational analysis based on molecular models of CH2 domain charge distribution indicated that the functional affinity was influenced by the specific charge location. N-glycans were essential for CH2-dependent enhancement of hemagglutination and complement activation. Oligomerization was independent of CH2 charge and glycosylation. We also verified that known C1q-binding motifs are functional in mouse IgG3 but not in IgG1 framework. We generated for the first time a gain-of-function antibody with properties transferred from IgG3 into IgG1 by replacing the CH2 domain. Finding that the CH2 domain of IgG3 governs unique properties of this isotype is likely to open an avenue toward the generation of IgG3-inspired antibodies that will be protective against existing or emerging lethal pathogens.
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Affiliation(s)
- Tomasz Klaus
- Laboratory of Monoclonal Antibodies, Małopolska Centre of Biotechnology, Jagiellonian University, Kraków, Poland.,Department of Cell Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland
| | - Joanna Bereta
- Department of Cell Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland
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Wong KJ, Baidoo KE, Nayak TK, Garmestani K, Brechbiel MW, Milenic DE. In Vitro and In Vivo Pre-Clinical Analysis of a F(ab')(2) Fragment of Panitumumab for Molecular Imaging and Therapy of HER1 Positive Cancers. EJNMMI Res 2014; 1. [PMID: 21845232 DOI: 10.1186/2191-219x-1-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The objective of this study was to characterize the in vitro and in vivo properties of the F(ab')(2) fragment of panitumumab and to investigate its potential for imaging and radioimmunotherapy. METHODS The panitumumab F(ab')(2) was generated by enzymatic pepsin digestion. After the integrity and immunoreactivity of the F(ab')(2) was evaluated, the fragment was radiolabeled. In vivo studies included direct quantitation of tumor targeting and normal organ distribution of the radiolabeled panitumumab F(ab')(2) as well as planar γ-scintigraphy and PET imaging. RESULTS The panitumumab F(ab')(2) was successfully produced by peptic digest. The F(ab')(2) was modified with the CHX-A"-DTPA chelate and efficiently radiolabeled with either (111)In or (86)Y. In vivo tumor targeting was achieved with acceptable uptake of radioactivity in the normal organs. The tumor targeting was validated by both imaging modalities with good visualization of the tumor at 24 h. CONCLUSIONS The panitumumab F(ab')(2) fragment is a promising candidate for imaging of HER1 positive cancers.
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Affiliation(s)
- Karen J Wong
- Molecular Imaging Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda MD 20892;
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8
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Jang JK, Khawli LA, Park R, Wu BW, Li Z, Canter D, Conti PS, Epstein AL. Cytoreductive chemotherapy improves the biodistribution of antibodies directed against tumor necrosis in murine solid tumor models. Mol Cancer Ther 2013; 12:2827-36. [PMID: 24130055 DOI: 10.1158/1535-7163.mct-13-0383] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Current strategies in cancer treatment employ combinations of different treatment modalities, which include chemotherapy, radiotherapy, immunotherapy, and surgery. Consistent with that approach, the present study demonstrates how chemotherapeutic agents can potentiate the delivery of radiolabeled, necrosis-targeting antibodies (chTNT-3, NHS76) to tumor. All chemotherapeutics in this study (5-fluorouracil, etoposide, vinblastine, paclitaxel, and doxorubicin) resulted in statistically significant increases in tumor uptake of radiolabeled antibodies and their F(ab')2 fragments compared to no pretreatment with chemotherapy. Labeled antibodies were administered at various time points following a single dose of chemotherapy in multiple tumor models, and the biodistribution of the antibodies was determined by measuring radioactivity in harvested tissues. MicroPET/CT was also done to demonstrate clinical relevancy of using chemotherapy pretreatment to increase antibody uptake. Results of biodistribution and imaging data reveal specific time frames following chemotherapy when necrosis-targeting antibodies are best delivered, either for imaging or radiotherapy. Thus, the present work offers the prospect of using cytoreductive chemotherapy to increase tumor accumulation of select therapeutic antibodies, especially when combined with other forms of immunotherapy, for the successful treatment of solid tumors.
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Affiliation(s)
- Julie K Jang
- Corresponding Author: Alan L. Epstein, Department of Pathology, University of Southern California, Keck School of Medicine, 2011 Zonal Avenue, HMR 205, Los Angeles, CA 90033.
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Khawli LA, Hu P, Epstein AL. Multiple uses of tumor necrosis therapy (TNT) for the treatment and imaging of solid tumors: Preclinical considerations and progress. ACTA ACUST UNITED AC 2006. [DOI: 10.1016/j.uct.2006.04.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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10
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Cass B, Pham PL, Kamen A, Durocher Y. Purification of recombinant proteins from mammalian cell culture using a generic double-affinity chromatography scheme. Protein Expr Purif 2005; 40:77-85. [PMID: 15721774 DOI: 10.1016/j.pep.2004.10.023] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2004] [Revised: 10/29/2004] [Indexed: 11/26/2022]
Abstract
Transient transfection of mammalian cells has proven to be a useful technique for the rapid production of recombinant proteins because of its ability to produce milligram quantities within 2 weeks following cloning of their corresponding cDNA. This rapid production also requires a fast and efficient purification scheme that can be applied generically, typically through the use of affinity tags such as the polyhistidine-tag for capture by immobilized metal-affinity chromatography (IMAC) or the Strep-tag II, which binds to the StrepTactin affinity ligand. However, one-step purification using either of these tags has disadvantages in terms of yield, elution conditions, and purity. Here, we show that the addition of both Strep-tag-II and (His)(8) to the C-terminal of r-proteins allows efficient purification by consecutive IMAC and StrepTactin affinity. This approach has been successfully demonstrated using the intracellular protein DsRed, as well as two secreted proteins, secreted alkaline phosphatase (SEAP) and vascular endothelial growth factor (VEGF), all produced by transient transfection of HEK293-EBNA1 cells in medium supplemented with bovine calf serum. All proteins were purified to >99% homogeneity with yields varying from 29 to 81%.
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Affiliation(s)
- Brian Cass
- Animal Cell Technology Group, Bioprocess Sector, Biotechnology Research Institute, National Research Council Canada, 6100 Royalmount Avenue, Montreal, Que., Canada H4P 2R2
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Khawli LA, Alauddin MM, Hu P, Epstein AL. Tumor targeting properties of indium-111 labeled genetically engineered Fab' and F(ab')2 constructs of chimeric tumor necrosis treatment (chTNT)-3 antibody. Cancer Biother Radiopharm 2005; 18:931-40. [PMID: 14969605 DOI: 10.1089/108497803322702897] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Genetic engineering techniques have allowed the construction of Fab' and F(ab')2 constructs of chimeric tumor necrosis treatment antibody (chTNT-3), a chimeric monoclonal antibody (MAb) that targets necrotic regions of solid tumors. The purpose of this study is to evaluate the in vitro and in vivo properties of Fab' and F(ab')2 constructs radiolabeled with indium-111 (111In) using diethylentriamine pentaacetic acid (DTPA) conjugation to develop a clinically useful imaging agent for the detection of necrosis in solid tumors. Optimization of the MAb-to-DTPA ratio showed that a 1:2 ratio gave the best immunoreactivity while providing good radiolabeling efficiency and high specific activity for all three DPTA conjugates. In addition, 111In-labeled Fab' and F(ab')2 conjugates were found to have faster whole body clearance times and better biodistribution profiles compared to parental 111In-labeled chTNT-3 in tumor-bearing mice. Although radiolabeled Fab' and F(ab')2 constructs showed lower tumor uptake than radiolabeled chTNT-3, biodistribution results showed that these constructs had significantly lower uptake in liver, spleen, and other normal organs (except the kidney), and therefore had higher tumor-to-organ ratios. In addition, a comparison of all derivatives showed that the F(ab')2 reagent gave the best results in tumor imaging studies. These results demonstrate that stable, a genetically engineered F(ab')2 construct can be successfully radiolabeled with 111In to produce potential imaging reagents for the imaging and monitoring of tumor necrosis.
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Affiliation(s)
- Leslie A Khawli
- University of Southern California, Keck School of Medicine, Los Angeles, CA, USA
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Biela BH, Khawli LA, Hu P, Epstein AL. Chimeric TNT-3/human beta-glucuronidase fusion proteins for antibody-directed enzyme prodrug therapy (ADEPT). Cancer Biother Radiopharm 2003; 18:339-53. [PMID: 12954121 DOI: 10.1089/108497803322285099] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
ADEPT (antibody-directed enzyme prodrug therapy) is a novel therapeutic approach that targets an enzyme into tumors to convert a relatively nontoxic prodrug into an active cytotoxic agent. This method has a number of advantages, including the reduction of systemic toxicity, but to date it has not realized its full potential. A critical component of ADEPT is the choice of the monoclonal antibody (MAb) to target the enzyme into the tumor mass. Prior studies have utilized MAbs directed against tumor cell surface antigens which are oftentimes labile and heterogeneous in nature and do not provide an ideal site for the enzyme. As an alternative approach, we now describe the use of Tumor Necrosis Therapy (TNT) MAbs to deliver the enzyme to necrotic regions of tumors in order to enhance the effectiveness of ADEPT. Biodistribution and autoradiographic studies performed using TNT MAbs have shown that localization of these antibodies occurs in degenerating cells and necrotic regions of tumors and that binding is retained within the tumor mass for extended periods of time. Since necrotic regions are often located in the center of tumors, are universal in nature, and constitute between 30 and 80% of the tumor mass, TNT MAbs may be ideal targeting agents for ADEPT. To test this hypothesis, fusion proteins consisting of single chain Fv (scFv), Fab, or F(ab')2 fragments of chTNT-3 and the human beta-glucuronidase (betaG) enzyme were constructed for ADEPT. Each of these reagents was tested to assess specificity and avidity of antigen binding as compared to the parental antibody. In addition, studies were performed to demonstrate enzymatic function of the fusion proteins and retention of catalytic activity in circulating blood, specific tissues, and tumor after in vivo administration. Pharmacokinetic and biodistribution studies of radiolabeled fusion proteins were conducted over time to evaluate the characteristics of the fusion proteins. Finally, one of the constructs (chTNT-3 Fab/betaG) was used in a pilot treatment study with a glucuronide prodrug of doxorubicin to demonstrate the anti-tumor activity of ADEPT using the chemoresistant MAD109 murine lung carcinoma tumor model transplanted into BALB/c mice. The results of these experiments show that all three constructs retained their antigen binding capability and demonstrated active enzymatic function against substrate in vitro. Moreover, after in vivo administration, the betaG enzyme was shown to localize to tumor and remain active for up to 9 days demonstrating a key characteristic of TNT targeting. Pharmacokinetic and biodistribution studies confirmed specific localization of the fusion proteins and rapid clearance from blood and normal tissues over time. Finally, therapeutic studies using only two doses of fusion protein followed by prodrug administration demonstrated active cytotoxicity against established tumors without systemic toxicity. These preliminary studies show that the use of TNT MAbs to target the enzyme to the tumor may be a significant advance in ADEPT and that further studies are warranted to test this novel therapeutic approach in the treatment of solid tumors.
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Affiliation(s)
- Barbara H Biela
- Department of Pathology, University of Southern California, Keck School of Medicine, Los Angeles, California 90033, USA
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13
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Khawli LA, Biela B, Hu P, Epstein AL. Comparison of recombinant derivatives of chimeric TNT-3 antibody for the radioimaging of solid tumors. HYBRIDOMA AND HYBRIDOMICS 2003; 22:1-9. [PMID: 12713684 DOI: 10.1089/153685903321538026] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Although intact monoclonal antibodies (MAbs) are well suited as therapeutic reagents, their relatively slow clearance rates render them less useful for imaging applications. Over the last several years, our laboratory has developed a unique targeting approach to solid tumors that utilizes MAbs directed against DNA and its components to bind to degenerating cells and necrotic regions of tumors in a specific manner. Because these MAbs have considerable potential for the early diagnosis of cancer and for the monitoring of cytoreductive therapies, the availability of an effective imaging agent is highly desirable. To accomplish this goal, a series of genetically engineered derivatives of MAb chTNT-3 including the single-chain Fv, diabody, triabody, Fab, and F(ab')(2) were generated and expressed in NS0 myeloma cells using the Glutamine Synthetase Amplification System. Initial in vitro studies demonstrated that each of the antibody derivatives maintained its antigen binding in a stable manner. In vivo analyses after radiolabeling were then performed to evaluate their pharmacokinetic, biodistribution, and tumor-imaging properties in solid tumor-bearing mice. The results of these studies showed that compared with intact parental chTNT-3, which has a half-life of 134.2 h, the smaller derivatives were eliminated more rapidly (4.9-8.1 h). Importantly, the smaller derivatives were found to have significantly higher tumor-to-organ ratios, but lower overall uptake levels compared with parental (125)I-chTNT-3 in two different tumor models. A comparison of the five derivatives showed that the F(ab')(2) reagent consistently gave the best results in imaging and biodistribution studies. Based upon these results, further studies are warranted to demonstrate the potential of this reagent for the diagnosis and monitoring of solid tumors using noninvasive imaging techniques such as immunoscintigraphy and positron emission tomography (PET).
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Affiliation(s)
- Leslie A Khawli
- Department of Pathology, University of Southern California, Keck School of Medicine, Los Angeles, CA 90033, USA
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