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Kumar C, Sharma R, Repaka KM, Pareri AU, Dash A. Camptothecin enhances 131I-rituximab-induced G1-arrest and apoptosis in Burkitt lymphoma cells. J Cancer Res Ther 2021; 17:943-950. [PMID: 34528546 DOI: 10.4103/jcrt.jcrt_1012_19] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Background Rituximab is a chimeric monoclonal antibody against CD20. It is an established immunotherapeutic agent for non-Hodgkin's lymphoma. Even though rituximab has been used in clinics for decades, only 50% of the patients respond to rituximab therapy. To enhance the in vitro effect of rituximab, it was labeled with Iodine-131 (131I) and combined effect of 131I-rituximab and camptothecin (CPT) was studied on a tumor cell line expressing CD20. Objective The aim is to study the magnitude of cell killing and the underlying mechanism responsible for enhancing in vitro therapeutic efficacy. Materials and Methods Rituximab was labeled with 131I by the iodogen method. Raji cells were pretreated with CPT (250 nM) for an hour followed by 131I-rituximab (0.37 and 3.7 MBq) and incubated for 24 h in a humidified atmosphere of CO2 incubator at 37°C. Subsequently, Raji cells were harvested and thoroughly washed to carry out studies of cellular toxicity, apoptosis, cell cycle, and mitogen-activated protein kinase (MAPK) pathways. Results Maximal inhibition of cell proliferation and enhancement of apoptotic cell death was observed in the cells treated with the combination of CPT and 131I-rituximab, compared to controls of CPT-treated and 131I-rituximab-treated cells. Raji cells undergo G1 arrest after 131I-rituximab treatment, which leads to apoptosis and was confirmed by the downregulation of bclxl protein. Expression of p38 was decreased while an increase in phosphorylation of p38 was observed in the combination treatment of CPT and 131I-rituximab. Conclusions It was concluded from the findings that CPT enhanced 131I-rituximab-induced apoptosis, G1 cell cycle arrest and p38 MAPK phosphorylation in Raji cells.
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Affiliation(s)
- Chandan Kumar
- Radiopharmaceuticals Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India
| | - Rohit Sharma
- Radiopharmaceuticals Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India
| | - Krishna Mohan Repaka
- Radiopharmaceutical Quality Control Program, Board of Radiation and Isotope Technology, Navi Mumbai, Maharashtra, India
| | | | - Ashutosh Dash
- Radiopharmaceuticals Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India
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Bar L, Dejeu J, Lartia R, Bano F, Richter RP, Coche-Guérente L, Boturyn D. Impact of Antigen Density on Recognition by Monoclonal Antibodies. Anal Chem 2020; 92:5396-5403. [DOI: 10.1021/acs.analchem.0c00092] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Laure Bar
- University of Grenoble-Alpes, CNRS, DCM UMR 5250, 570 rue de la chimie, CS 40700, 38058 Grenoble Cedex 9, France
| | - Jérôme Dejeu
- University of Grenoble-Alpes, CNRS, DCM UMR 5250, 570 rue de la chimie, CS 40700, 38058 Grenoble Cedex 9, France
| | - Rémy Lartia
- University of Grenoble-Alpes, CNRS, DCM UMR 5250, 570 rue de la chimie, CS 40700, 38058 Grenoble Cedex 9, France
| | - Fouzia Bano
- University of Leeds, School of Biomedical Sciences, Faculty of Biological Sciences, School of Physics and Astronomy, Faculty of Engineering and Physical Sciences, Astbury Center for Structural Molecular Biology, and Bragg Centre for Materials Research, Leeds LS2 9JT, United Kingdom
| | - Ralf P. Richter
- University of Leeds, School of Biomedical Sciences, Faculty of Biological Sciences, School of Physics and Astronomy, Faculty of Engineering and Physical Sciences, Astbury Center for Structural Molecular Biology, and Bragg Centre for Materials Research, Leeds LS2 9JT, United Kingdom
| | - Liliane Coche-Guérente
- University of Grenoble-Alpes, CNRS, DCM UMR 5250, 570 rue de la chimie, CS 40700, 38058 Grenoble Cedex 9, France
| | - Didier Boturyn
- University of Grenoble-Alpes, CNRS, DCM UMR 5250, 570 rue de la chimie, CS 40700, 38058 Grenoble Cedex 9, France
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Ballinger JR. Theranostic radiopharmaceuticals: established agents in current use. Br J Radiol 2018; 91:20170969. [PMID: 29474096 DOI: 10.1259/bjr.20170969] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Although use of the term "theranostic" is relatively recent, the concept goes back to the earliest days of nuclear medicine, with the use of radioiodine for diagnosis and therapy of benign and malignant thyroid disease being arguably the most successful molecular radiotherapy in history. A diagnostic scan with 123I-, 124I-, or a low activity of 131I-iodide is followed by therapy with high activity 131I-iodide. Similarly, adrenergic tumours such as phaeochromocytoma and neuroblastoma can be imaged with 123I-metaiodobenzylguanidine and treated with 131I-metaiodobenzylguanidine. Bone scintigraphy can be used to select patients with painful bone metastases from prostate cancer who may benefit from treatment with beta- or alpha-particle emitting bone seeking agents, the most recent and successful of which is 223Ra radium chloride. Anti-CD20 monoclonal antibodies can be used to image and treat non-Hodgkins lymphoma, though this has not been as commercially successful as initially predicted. More recently established theranostics include somatostatin receptor targeting peptides for diagnosis and treatment of neuroendocrine tumours with agents such as 68Ga-DOTATATE and 177Lu-DOTATATE, respectively. Finally, agents which target prostate-specific membrane antigen are becoming increasingly widely available, despite the current lack of a commercial product. With the recent licensing of the somatostatin peptides and the rapid adoption of 68Ga- and 177Lu-labelled prostate-specific membrane antigen targeting agents, we have built upon the experience of radioiodine and are already seeing a great expansion in the availability of widely accepted theranostic radiopharmaceuticals.
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Affiliation(s)
- James R Ballinger
- 1 Department of Imaging Chemistry and Biology, School of Biomedical Engineering and Imaging Sciences, King's College London , London , UK
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Popov J, Gilabert-Oriol R, Bally MB. Unique therapeutic properties and preparation methodology of multivalent rituximab-lipid nanoparticles. Eur J Pharm Biopharm 2017; 117:256-269. [DOI: 10.1016/j.ejpb.2017.04.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 04/18/2017] [Accepted: 04/21/2017] [Indexed: 01/20/2023]
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Kameswaran M, Pandey U, Dash A, Samuel G, Venkatesh M. Preparation & in vitro evaluation of ⁹⁰Y-DOTA-rituximab. Indian J Med Res 2017; 143:57-65. [PMID: 26997015 PMCID: PMC4822370 DOI: 10.4103/0971-5916.178593] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Background & objectives: Radioimmunotherapy is extensively being used for the treatment of non-Hodgkin's lymphoma (NHL). Use of rituximab, a chimeric anti-CD20 antibody directed against the CD20 antigen in combination with suitable beta emitters is expected to result in good treatment response by its cross-fire and bystander effects. The present work involves the conjugation of p-isothiocyanatobenzyl DOTA (p-SCN-Bn-DOTA) to rituximab, its radiolabelling with 90Y and in vitro and in vivo evaluation to determine its potential as a radioimmunotherapeutic agent. Methods: Rituximab was conjugated with p-SCN-Bn-DOTA at 1:1 antibody: DOTA molar ratio. The number of DOTA molecules linked to one molecule of rituximab was determined by radioassay and spectroscopic assay. Radiolabelling of rituximab with 90Y was carried out and its in vitro stability was evaluated. In vitro cell binding studies were carried out in Raji cells expressing CD20 antigen. Biodistribution studies were carried out in normal Swiss mice. Results: Using both radioassay and spectroscopic method, it was determined that about five molecules of DOTA were linked to rituximab. Radiolabelling of the rituximab conjugate with 90Y and subsequent purification on PD-10 column gave a product with radiochemical purity (RCP) > 98 per cent which was retained at > 90 per cent up to 72 h when stored at 37°C. In vitro cell binding experiments of 90Y-DOTA-rituximab with Raji cells exhibited specific binding of 20.7 ± 0.1 per cent with 90Y-DOTA-rituximab which reduced to 15.5 ± 0.2 per cent when incubated with cold rituximab. The equilibrium constant Kd for 90Y-DOTA-Rituximab was determined to be 3.38 nM. Radiolabelled antibody showed clearance via hepatobiliary and renal routes and activity in tibia was found to be quite low indicating in vivo stability of 90Y-DOTA-rituximab. Interpretation & conclusions: p-SCN-Bn-DOTA was conjugated with rituximab and radiolabelling with 90Y was carried out. In vitro studies carried out in Raji cells showed the specificity of the radiolabelled conjugate suggesting the potential uitability of the formulation as a radiopharmaceutical for therapy of NHL.
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Affiliation(s)
- Mythili Kameswaran
- Isotope Production & Applications Division, Bhabha Atomic Research Centre, Mumbai, India
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Kameswaran M, Gota V, Ambade R, Gupta S, Dash A. Preparation and preclinical evaluation of 131 I-trastuzumab for breast cancer. J Labelled Comp Radiopharm 2016; 60:12-19. [PMID: 27813128 DOI: 10.1002/jlcr.3465] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2016] [Revised: 08/30/2016] [Accepted: 09/08/2016] [Indexed: 11/10/2022]
Abstract
Trastuzumab that targets the human epidermal growth factor receptor type 2 (HER2) is known to benefit patients with HER2+ metastatic breast cancer. The objective was to explore the potential of 131 I-trastuzumab for treatment of breast cancers. Radioiodination of trastuzumab was carried out by chloramine-T method, purified by using PD-10 column, and characterized by size exclusion high-performance liquid chromatography on a gel column. In vitro studies were carried out in HER2+ cells to determine the specificity of the radioimmunoconjugate. Uptake and retention of 131 I-trastuzumab were determined by biodistribution studies in tumor-bearing non-obese diabetic/severe combined immunodeficiency and normal severe combined immunodeficiency mice. The radiochemical purity (RCP) of 131 I-trastuzumab was 98 ± 0.4% with retention time of 17 minutes by high-performance liquid chromatography. In vitro stability studies exhibited RCP of more than 90% in serum at 37°C after 120 hours of radioiodination. In vitro cell binding with 131 I-trastuzumab in HER2+ cells showed binding of 28% to 35% which was inhibited significantly, with unlabeled trastuzumab confirming its specificity. Kd value of 131 I-trastuzumab was 0.5 nM, while its immunoreactivity was more than 80%. Uptake of more than 12% and retention were observed in the tumors up to 120 hours p.i. 131 I-trastuzumab prepared in-house-exhibited RCP of more than 98%, excellent immunoreactivity, affinity to HER2+ cell lines and good tumor uptake thereby indicating its potential for further evaluation in HER2+ breast cancers.
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Affiliation(s)
- Mythili Kameswaran
- Isotope Production and Applications Division, Bhabha Atomic Research Centre, Mumbai, India
| | - Vikram Gota
- Advanced Centre for Treatment Research and Education in Cancer (ACTREC), Navi Mumbai, India
| | - Rajwardhan Ambade
- Isotope Production and Applications Division, Bhabha Atomic Research Centre, Mumbai, India
| | - Sudeep Gupta
- Advanced Centre for Treatment Research and Education in Cancer (ACTREC), Navi Mumbai, India
| | - Ashutosh Dash
- Isotope Production and Applications Division, Bhabha Atomic Research Centre, Mumbai, India
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Dekempeneer Y, Keyaerts M, Krasniqi A, Puttemans J, Muyldermans S, Lahoutte T, D'huyvetter M, Devoogdt N. Targeted alpha therapy using short-lived alpha-particles and the promise of nanobodies as targeting vehicle. Expert Opin Biol Ther 2016; 16:1035-47. [PMID: 27145158 PMCID: PMC4940885 DOI: 10.1080/14712598.2016.1185412] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Introduction: The combination of a targeted biomolecule that specifically defines the target and a radionuclide that delivers a cytotoxic payload offers a specific way to destroy cancer cells. Targeted radionuclide therapy (TRNT) aims to deliver cytotoxic radiation to cancer cells and causes minimal toxicity to surrounding healthy tissues. Recent advances using α-particle radiation emphasizes their potential to generate radiation in a highly localized and toxic manner because of their high level of ionization and short range in tissue. Areas covered: We review the importance of targeted alpha therapy (TAT) and focus on nanobodies as potential beneficial vehicles. In recent years, nanobodies have been evaluated intensively as unique antigen-specific vehicles for molecular imaging and TRNT. Expert opinion: We expect that the efficient targeting capacity and fast clearance of nanobodies offer a high potential for TAT. More particularly, we argue that the nanobodies’ pharmacokinetic properties match perfectly with the interesting decay properties of the short-lived α-particle emitting radionuclides Astatine-211 and Bismuth-213 and offer an interesting treatment option particularly for micrometastatic cancer and residual disease.
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Affiliation(s)
- Yana Dekempeneer
- a Vrije Universiteit Brussel, In Vivo Cellular and Molecular Imaging , Brussels , Belgium
| | - Marleen Keyaerts
- a Vrije Universiteit Brussel, In Vivo Cellular and Molecular Imaging , Brussels , Belgium.,b Nuclear Medicine Department , UZ Brussel , Brussels , Belgium
| | - Ahmet Krasniqi
- a Vrije Universiteit Brussel, In Vivo Cellular and Molecular Imaging , Brussels , Belgium
| | - Janik Puttemans
- a Vrije Universiteit Brussel, In Vivo Cellular and Molecular Imaging , Brussels , Belgium
| | - Serge Muyldermans
- c Vrije Universiteit Brussel , Laboratory of Cellular and Molecular Immunology , Brussels , Belgium
| | - Tony Lahoutte
- a Vrije Universiteit Brussel, In Vivo Cellular and Molecular Imaging , Brussels , Belgium.,b Nuclear Medicine Department , UZ Brussel , Brussels , Belgium
| | - Matthias D'huyvetter
- a Vrije Universiteit Brussel, In Vivo Cellular and Molecular Imaging , Brussels , Belgium
| | - Nick Devoogdt
- a Vrije Universiteit Brussel, In Vivo Cellular and Molecular Imaging , Brussels , Belgium
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Kameswaran M, Pandey U, Dhakan C, Pathak K, Gota V, Vimalnath K, Dash A, Samuel G. Synthesis and Preclinical Evaluation of 177Lu-CHX-A”-DTPA-Rituximab as a Radioimmunotherapeutic Agent for Non-Hodgkin's Lymphoma. Cancer Biother Radiopharm 2015; 30:240-6. [DOI: 10.1089/cbr.2015.1836] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Mythili Kameswaran
- Isotope Production and Applications Division, Bhabha Atomic Research Centre, Mumbai, India
| | - Usha Pandey
- Isotope Production and Applications Division, Bhabha Atomic Research Centre, Mumbai, India
| | - Chetan Dhakan
- Department of Clinical Pharmacology, ACTREC, Tata Memorial Center, Navi Mumbai, India
| | - Kamal Pathak
- Department of Clinical Pharmacology, ACTREC, Tata Memorial Center, Navi Mumbai, India
| | - Vikram Gota
- Department of Clinical Pharmacology, ACTREC, Tata Memorial Center, Navi Mumbai, India
| | - K.V. Vimalnath
- Isotope Production and Applications Division, Bhabha Atomic Research Centre, Mumbai, India
| | - Ashutosh Dash
- Isotope Production and Applications Division, Bhabha Atomic Research Centre, Mumbai, India
| | - Grace Samuel
- Isotope Production and Applications Division, Bhabha Atomic Research Centre, Mumbai, India
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Pandey U, Kameswaran M, Dev Sarma H, Samuel G. 99mTc carbonyl DTPA–Rituximab: Preparation and preliminary bioevaluation. Appl Radiat Isot 2014; 86:52-6. [DOI: 10.1016/j.apradiso.2013.12.036] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 11/18/2013] [Accepted: 12/27/2013] [Indexed: 12/16/2022]
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Dahle J, Jonasdottir TJ, Heyerdahl H, Nesland JM, Borrebaek J, Hjelmerud AK, Larsen RH. Assessment of long-term radiotoxicity after treatment with the low-dose-rate alpha-particle-emitting radioimmunoconjugate (227)Th-rituximab. Eur J Nucl Med Mol Imaging 2010; 37:93-102. [PMID: 19593562 DOI: 10.1007/s00259-009-1197-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Accepted: 06/07/2009] [Indexed: 11/24/2022]
Abstract
PURPOSE The anti-CD20 antibody rituximab labelled with the alpha-particle-emitting radionuclide (227)Th is of interest as a radiotherapeutic agent for treatment of lymphoma. Complete regression of human lymphoma Raji xenografts in 60% of mice treated with 200 kBq/kg (227)Th-rituximab has been observed. To evaluate possible late side effects of (227)Th-rituximab, the long-term radiotoxicity of this potential radiopharmaceutical was investigated. METHODS BALB/c mice were injected with saline, cold rituximab or 50, 200 or 1,000 kBq/kg (227)Th-rituximab and followed for up to 1 year. In addition, nude mice with Raji xenografts treated with various doses of (227)Th-rituximab were also included in the study. Toxicity was evaluated by measurements of mouse body weight, white blood cell (WBC) and platelet counts, serum clinical chemistry parameters and histological examination of tissues. RESULTS Only the 1,000 kBq/kg dosage resulted in decreased body weight of the BALB/c mice. There was a significant but temporary decrease in WBC and platelet count in mice treated with 400 and 1,000 kBq/kg (227)Th-rituximab. Therefore, the no-observed-adverse-effect level (NOAEL) was 200 kBq/kg. The maximum tolerated activity was between 600 and 1,000 kBq/kg. No significant signs of toxicity were observed in histological sections in any examined tissue. There were significantly (p < 0.05), but transiently, higher concentrations of serum bile acids and aspartate aminotransferase in mice treated with either (227)Th-rituximab or non-labelled antibody when compared with control mice. The maximum tolerated dose to bone marrow was between 2.1 and 3.5 Gy. CONCLUSION Therapeutically relevant dose levels of (227)Th-rituximab were well tolerated in mice. Bone marrow suppression, as indicated by decrease in WBC count, was the dose-limiting radiotoxicity. These toxicity data together with anti-tumour activity data in a CD20-positive xenograft mouse model indicate that therapeutic effects could be obtained with relatively safe dosage levels of the radioimmunoconjugate.
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Affiliation(s)
- Jostein Dahle
- Department of Radiation Biology, The Norwegian Radium Hospital, Oslo University Hospital, 0310 Oslo, Norway.
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Dahle J, Krogh C, Melhus KB, Borrebaek J, Larsen RH, Kvinnsland Y. In vitro cytotoxicity of low-dose-rate radioimmunotherapy by the alpha-emitting radioimmunoconjugate Thorium-227-DOTA-rituximab. Int J Radiat Oncol Biol Phys 2009; 75:886-95. [PMID: 19679402 DOI: 10.1016/j.ijrobp.2009.04.062] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2009] [Revised: 04/28/2009] [Accepted: 04/28/2009] [Indexed: 11/19/2022]
Abstract
PURPOSE To determine whether the low-dose-rate alpha-particle-emitting radioimmunoconjugate (227)Th-1,4,7,10-p-isothiocyanato-benzyl-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-rituximab can be used to inactivate lymphoma cells growing as single cells and small colonies. METHODS AND MATERIALS CD20-positive lymphoma cell lines were treated with (227)Th-DOTA-rituximab for 1-5 weeks. To simulate the in vivo situation with continuous but decreasing supply of radioimmunoconjugates from the blood pool, the cells were not washed after incubation with (227)Th-DOTA-rituximab, but half of the medium was replaced with fresh medium, and cell concentration and cell-bound activity were determined every other day after start of incubation. A microdosimetric model was established to estimate the average number of hits in the nucleus for different localizations of activity. RESULTS There was a specific targeted effect on cell growth of the (227)Th-DOTA-rituximab treatment. Although the cells were not washed after incubation with (227)Th-DOTA-rituximab, the average contribution of activity in the medium to the mean dose was only 6%, whereas the average contribution from activity on the cells' own surface was 78%. The mean dose rates after incubation with 800 Bq/mL (227)Th-DOTA-rituximab varied from 0.01 to 0.03 cGy/min. The average delay in growing from 10(5) to 10(7) cells/mL was 15 days when the cells were treated with a mean absorbed radiation dose of 2 Gy alpha-particle radiation from (227)Th-DOTA-rituximab, whereas it was 11 days when the cells were irradiated with 6 Gy of X-radiation. The relative biologic effect of the treatment was estimated to be 2.9-3.4. CONCLUSIONS The low-dose-rate radioimmunoconjugate (227)Th-DOTA-rituximab is suitable for inactivation of single lymphoma cells and small colonies of lymphoma cells.
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Affiliation(s)
- Jostein Dahle
- Department of Radiation Biology, Norwegian Radium Hospital, Montebello, Oslo, Norway.
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Tolmachev V, Wållberg H, Andersson K, Wennborg A, Lundqvist H, Orlova A. The influence of Bz-DOTA and CHX-A″-DTPA on the biodistribution of ABD-fused anti-HER2 Affibody molecules: implications for 114mIn-mediated targeting therapy. Eur J Nucl Med Mol Imaging 2009; 36:1460-8. [DOI: 10.1007/s00259-009-1134-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2008] [Accepted: 03/23/2009] [Indexed: 10/20/2022]
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Properties and structure-function relationships of veltuzumab (hA20), a humanized anti-CD20 monoclonal antibody. Blood 2008; 113:1062-70. [PMID: 18941114 DOI: 10.1182/blood-2008-07-168146] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Veltuzumab is a humanized anti-CD20 monoclonal antibody with complementarity-determining regions (CDRs) identical to rituximab, except for one residue at the 101st position (Kabat numbering) in CDR3 of the variable heavy chain (V(H)), having aspartic acid (Asp) instead of asparagine (Asn), with framework regions of epratuzumab, a humanized anti-CD22 antibody. When compared with rituximab, veltuzumab has significantly reduced off-rates in 3 human lymphoma cell lines tested, as well as increased complement-dependent cytotoxicity in 1 of 3 cell lines, but no other in vitro differences. Mutation studies confirmed that the differentiation of the off-rate between veltuzumab and rituximab is related to the single amino acid change in CDR3-V(H). Studies of intraperitoneal and subcutaneous doses in mouse models of human lymphoma and in normal cynomolgus monkeys disclosed that low doses of veltuzumab control tumor growth or deplete circulating or sessile B cells. Low- and high-dose veltuzumab were significantly more effective in vivo than rituximab in 3 lymphoma models. These findings are consistent with activity in patients with non-Hodgkin lymphoma given low intravenous or subcutaneous doses of veltuzumab. Thus, changing Asn(101) to Asp(101) in CDR3-V(H) of rituximab is responsible for veltuzumab's lower off-rate and apparent improved potency in preclinical models that could translate into advantages in patients.
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