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Li J, Huang T, Hua J, Wang Q, Su Y, Chen P, Bidlingmaier S, Li A, Xie Z, Bidkar AP, Shen S, Shi W, Seo Y, Flavell RR, Gioeli D, Dreicer R, Li H, Liu B, He J. CD46 targeted 212Pb alpha particle radioimmunotherapy for prostate cancer treatment. J Exp Clin Cancer Res 2023; 42:61. [PMID: 36906664 PMCID: PMC10007843 DOI: 10.1186/s13046-023-02636-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Accepted: 03/01/2023] [Indexed: 03/13/2023] Open
Abstract
We recently identified CD46 as a novel prostate cancer cell surface antigen that shows lineage independent expression in both adenocarcinoma and small cell neuroendocrine subtypes of metastatic castration resistant prostate cancer (mCRPC), discovered an internalizing human monoclonal antibody YS5 that binds to a tumor selective CD46 epitope, and developed a microtubule inhibitor-based antibody drug conjugate that is in a multi-center phase I trial for mCRPC (NCT03575819). Here we report the development of a novel CD46-targeted alpha therapy based on YS5. We conjugated 212Pb, an in vivo generator of alpha-emitting 212Bi and 212Po, to YS5 through the chelator TCMC to create the radioimmunoconjugate, 212Pb-TCMC-YS5. We characterized 212Pb-TCMC-YS5 in vitro and established a safe dose in vivo. We next studied therapeutic efficacy of a single dose of 212Pb-TCMC-YS5 using three prostate cancer small animal models: a subcutaneous mCRPC cell line-derived xenograft (CDX) model (subcu-CDX), an orthotopically grafted mCRPC CDX model (ortho-CDX), and a prostate cancer patient-derived xenograft model (PDX). In all three models, a single dose of 0.74 MBq (20 µCi) 212Pb-TCMC-YS5 was well tolerated and caused potent and sustained inhibition of established tumors, with significant increases of survival in treated animals. A lower dose (0.37 MBq or 10 µCi 212Pb-TCMC-YS5) was also studied on the PDX model, which also showed a significant effect on tumor growth inhibition and prolongation of animal survival. These results demonstrate that 212Pb-TCMC-YS5 has an excellent therapeutic window in preclinical models including PDXs, opening a direct path for clinical translation of this novel CD46-targeted alpha radioimmunotherapy for mCRPC treatment.
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Affiliation(s)
- Jun Li
- Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, VA, 22903, USA
- Department of Nuclear Medicine, Peking University Shenzhen Hospital, Guangdong, 518036, China
| | - Tao Huang
- Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, VA, 22903, USA
| | - Jun Hua
- Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, VA, 22903, USA
- Department of Nuclear Medicine, Chongqing Cancer Hospital, Chongqing University, Chongqing, China
| | - Qiong Wang
- Department of Urology, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
- Department of Pathology, University of Virginia, Charlottesville, VA, 22903, USA
| | - Yang Su
- Department of Anesthesia, University of California, San Francisco, CA, 94110, USA
| | - Ping Chen
- Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, VA, 22903, USA
- Department of Nuclear Medicine, Peking University Shenzhen Hospital, Guangdong, 518036, China
| | - Scott Bidlingmaier
- Department of Anesthesia, University of California, San Francisco, CA, 94110, USA
| | - Allan Li
- Department of Anesthesia, University of California, San Francisco, CA, 94110, USA
| | - Zhongqiu Xie
- Department of Pathology, University of Virginia, Charlottesville, VA, 22903, USA
| | - Anil P Bidkar
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, 94110, USA
| | - Sui Shen
- Department of Radiation Oncology, University of Alabama, Birmingham, AL, 35233, USA
| | - Weibin Shi
- Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, VA, 22903, USA
| | - Youngho Seo
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, 94110, USA
- UCSF Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA, 94110, USA
| | - Robert R Flavell
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, 94110, USA
- UCSF Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA, 94110, USA
| | - Daniel Gioeli
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, VA, 22903, USA
- UVA Comprehensive Cancer Center, University of Virginia, Charlottesville, VA, 22903, USA
| | - Robert Dreicer
- UVA Comprehensive Cancer Center, University of Virginia, Charlottesville, VA, 22903, USA
- Department of Medicine, University of Virginia, Charlottesville, VA, 22903, USA
| | - Hui Li
- Department of Pathology, University of Virginia, Charlottesville, VA, 22903, USA
- UVA Comprehensive Cancer Center, University of Virginia, Charlottesville, VA, 22903, USA
| | - Bin Liu
- Department of Anesthesia, University of California, San Francisco, CA, 94110, USA.
- UCSF Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA, 94110, USA.
| | - Jiang He
- Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, VA, 22903, USA.
- UVA Comprehensive Cancer Center, University of Virginia, Charlottesville, VA, 22903, USA.
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Li RG, Stenberg VY, Larsen RH. An Experimental Generator for Production of High-Purity 212Pb for Use in Radiopharmaceuticals. J Nucl Med 2023; 64:173-176. [PMID: 35798556 PMCID: PMC9841245 DOI: 10.2967/jnumed.122.264009] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 06/22/2022] [Accepted: 06/22/2022] [Indexed: 01/28/2023] Open
Abstract
The feasibility, performance, and radiation safety of an experimental generator were evaluated to efficiently produce 212Pb intended for radiopharmaceuticals. Methods: The generator consisted of a flask with a removable cap containing a source of 224Ra or 228Th absorbed on quartz wool. Gaseous 220Rn emanated from the decaying source, which subsequently decayed to 212Pb, which was adsorbed on the flask's interior surface. The 212Pb was collected by washing the flask with 0.5-1 mL of 0.1 M HCl. Results: The generator collector flask trapped 62%-68% of the 212Pb, of which more than 87% (tested up to 26 MBq) could be harvested. The obtained 212Pb solution had a high purity (>99.98%) and could be used for the preparation of radioconjugates with more than 97% radiochemical purity. Future designs of the generator should aim to further reduce the risk of radon and γ-energy exposure to operators. Conclusion: The presented technology is a promising method for easy and convenient 212Pb production.
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Affiliation(s)
- Ruth Gong Li
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway; .,Department of Radiation Biology, Institute of Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway.,Oncoinvent AS, Oslo, Norway
| | - Vilde Yuli Stenberg
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway;,Department of Radiation Biology, Institute of Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway;,ArtBio AS, Oslo, Norway; and
| | - Roy Hartvig Larsen
- Oncoinvent AS, Oslo, Norway;,ArtBio AS, Oslo, Norway; and,Sciencons AS, Oslo, Norway
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3
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Bergeron DE, Cessna JT, Fitzgerald RP, Laureano-Pérez L, Pibida L, Zimmerman BE. Primary standardization of 212Pb activity by liquid scintillation counting. Appl Radiat Isot 2022; 190:110473. [PMID: 36201936 PMCID: PMC9827475 DOI: 10.1016/j.apradiso.2022.110473] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 09/16/2022] [Accepted: 09/16/2022] [Indexed: 01/11/2023]
Abstract
An activity standard for 212Pb in equilibrium with its progeny was realized, based on triple-to-double coincidence ratio (TDCR) liquid scintillation (LS) counting. A Monte Carlo-based approach to estimating uncertainties due to nuclear decay data (branching ratios, beta endpoint energies, γ-ray energies, and conversion coefficients for 212Pb and 208Tl) led to combined standard uncertainties ≤ 0.20 %. Confirmatory primary measurements were made by LS efficiency tracing with tritium and 4παβ(LS)-γ(NaI(Tl)) anticoincidence counting. The standard is discussed in relation to current approaches to 212Pb activity calibration. In particular, potential biases encountered when using inappropriate radionuclide calibrator settings are discussed.
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Affiliation(s)
- Denis E Bergeron
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA.
| | - Jeffrey T Cessna
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Ryan P Fitzgerald
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Lizbeth Laureano-Pérez
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Leticia Pibida
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Brian E Zimmerman
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
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Tornes AJK, Stenberg VY, Larsen RH, Bruland ØS, Revheim ME, Juzeniene A. Targeted alpha therapy with the 224Ra/ 212Pb-TCMC-TP-3 dual alpha solution in a multicellular tumor spheroid model of osteosarcoma. Front Med (Lausanne) 2022; 9:1058863. [PMID: 36507500 PMCID: PMC9727293 DOI: 10.3389/fmed.2022.1058863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 11/04/2022] [Indexed: 11/24/2022] Open
Abstract
Osteosarcoma patients with overt metastases at primary diagnosis have a 5-year survival rate of less than 20%. TP-3 is a murine IgG2b monoclonal antibody with high affinity for an epitope residing on the p80 osteosarcoma cell surface membrane antigen. The tumor-associated antigen p80 is overexpressed in osteosarcomas, and has very low normal tissue expression. We propose a novel dual alpha targeting solution containing two radionuclides from the same decay chain, including the bone-seeking 224Ra, and cancer cell-surface seeking 212Pb-TCMC-TP-3 for the treatment of osteoblastic bone cancers, circulating cancer cells and micrometastases. In this in vitro study, the cytotoxic effects of 212Pb-TCMC-TP-3 (single alpha solution) and 224Ra/212Pb-TCMC-TP-3 (dual alpha solution) were investigated in a multicellular spheroid model mimicking micrometastatic disease in osteosarcoma. OHS spheroids with diameters of 253 ± 98 μm treated with 4.5, 2.7, and 3.3 kBq/ml of 212Pb-TCMC-TP-3 for 1, 4, and 24 h, respectively, were disintegrated within 3 weeks. The 212Pb-TCMC-TP-3 induced a 7-fold delay in spheroid doubling time compared to a 28-times higher dose with the non-specific 212Pb-TCMC-rituximab. The 224Ra/212Pb-TCMC-TP-3 completely disintegrated spheroids with diameters of 218-476 μm within 3 and 2 weeks after 4 and 24 h incubation with 5 kBq/ml, respectively. Treatment with 1 kBq/ml of 224Ra/212Pb-TCMC-TP-3 for 24 h caused an 11.4-fold reduction in spheroid viability compared with unconjugated 224Ra/212Pb. The single and dual alpha solutions with TP-3 showed cytotoxicity in spheroids of clinically relevant size, which warrant further testing of the dual alpha solution using in vivo osteosarcoma models.
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Affiliation(s)
- Anna Julie Kjøl Tornes
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway,ArtBio AS, Oslo, Norway,Institute of Clinical Medicine, University of Oslo, Oslo, Norway,*Correspondence: Anna Julie Kjøl Tornes,
| | - Vilde Yuli Stenberg
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway,ArtBio AS, Oslo, Norway,Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | | | - Øyvind Sverre Bruland
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway,Department of Oncology, Oslo University Hospital, Oslo, Norway
| | - Mona-Elisabeth Revheim
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway,Division of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo, Norway
| | - Asta Juzeniene
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway,Department of Physics, University of Oslo, Oslo, Norway
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Stenberg VY, Tornes AJK, Nilsen HR, Revheim ME, Bruland ØS, Larsen RH, Juzeniene A. Factors Influencing the Therapeutic Efficacy of the PSMA Targeting Radioligand 212Pb-NG001. Cancers (Basel) 2022; 14:cancers14112784. [PMID: 35681766 PMCID: PMC9179904 DOI: 10.3390/cancers14112784] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 05/18/2022] [Accepted: 06/01/2022] [Indexed: 12/10/2022] Open
Abstract
Simple Summary Prostate-specific membrane antigen (PSMA) is a protein overexpressed in metastatic castration-resistant prostate cancer and a promising target for targeted radionuclide therapy. PSMA-targeted alpha therapy is of growing interest due to the high-emission energy and short range of alpha particles, resulting in a prominent cytotoxic potency. This study assesses the influence of various factors on the in vitro and in vivo therapeutic efficacy of the alpha particle generating PSMA-targeting radioligand 212Pb-NG001. Abstract This study aimed to determine the influence of cellular PSMA expression, radioligand binding and internalization, and repeated administrations on the therapeutic effects of the PSMA-targeting radioligand 212Pb-NG001. Cellular binding and internalization, cytotoxicity, biodistribution, and the therapeutic efficacy of 212Pb-NG001 were investigated in two human prostate cancer cell lines with different PSMA levels: C4-2 (PSMA+) and PC-3 PIP (PSMA+++). Despite 10-fold higher PSMA expression on PC-3 PIP cells, cytotoxicity and therapeutic efficacy of the radioligand was only 1.8-fold better than for the C4-2 model, possibly explained by lower cellular internalization and less blood-rich stroma in PC-3 PIP xenografts. Mice bearing subcutaneous PC-3 PIP xenografts were treated with 0.2, 0.4, and 0.8 MBq of 212Pb-NG001 that resulted in therapeutic indexes of 2.7, 3.0, and 3.5, respectively. A significant increase in treatment response was observed in mice that received repeated injections compared to the corresponding single dose (therapeutic indexes of 3.6 for 2 × 0.2 MBq and 4.4 for 2 × 0.4 MBq). The results indicate that 212Pb-NG001 can induce therapeutic effects at clinically transferrable doses, both in the C4-2 model that resembles solid tumors and micrometastases with natural PSMA expression and in the PC-3 PIP model that mimics poorly vascularized metastases.
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Affiliation(s)
- Vilde Yuli Stenberg
- Department of Radiation Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo University Hospital, 0379 Oslo, Norway; (A.J.K.T.); (A.J.)
- Nucligen AS, 0379 Oslo, Norway;
- Institute of Clinical Medicine, University of Oslo, 0318 Oslo, Norway; (M.-E.R.); (Ø.S.B.)
- Correspondence: ; Tel.: +47-9012-8434
| | - Anna Julie Kjøl Tornes
- Department of Radiation Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo University Hospital, 0379 Oslo, Norway; (A.J.K.T.); (A.J.)
- Nucligen AS, 0379 Oslo, Norway;
- Institute of Clinical Medicine, University of Oslo, 0318 Oslo, Norway; (M.-E.R.); (Ø.S.B.)
| | - Hogne Røed Nilsen
- Department of Pathology, Rikshospitalet, Oslo University Hospital, 0372 Oslo, Norway;
| | - Mona-Elisabeth Revheim
- Institute of Clinical Medicine, University of Oslo, 0318 Oslo, Norway; (M.-E.R.); (Ø.S.B.)
- Division of Radiology and Nuclear Medicine, Oslo University Hospital, 0379 Oslo, Norway
| | - Øyvind Sverre Bruland
- Institute of Clinical Medicine, University of Oslo, 0318 Oslo, Norway; (M.-E.R.); (Ø.S.B.)
- Department of Oncology, The Norwegian Radium Hospital, Oslo University Hospital, 0379 Oslo, Norway
| | | | - Asta Juzeniene
- Department of Radiation Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo University Hospital, 0379 Oslo, Norway; (A.J.K.T.); (A.J.)
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Bergeron DE, Kossert K, Collins SM, Fenwick AJ. Realization and dissemination of activity standards for medically important alpha-emitting radionuclides. Appl Radiat Isot 2022; 184:110161. [DOI: 10.1016/j.apradiso.2022.110161] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 02/16/2022] [Accepted: 02/22/2022] [Indexed: 11/27/2022]
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7
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A Novel Single-Step-Labeled 212Pb-CaCO 3 Microparticle for Internal Alpha Therapy: Preparation, Stability, and Preclinical Data from Mice. MATERIALS 2021; 14:ma14237130. [PMID: 34885283 PMCID: PMC8658347 DOI: 10.3390/ma14237130] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/19/2021] [Accepted: 11/19/2021] [Indexed: 02/06/2023]
Abstract
Lead-212 is recognized as a promising radionuclide for targeted alpha therapy for tumors. Many studies of 212Pb-labeling of various biomolecules through bifunctional chelators have been conducted. Another approach to exploiting the cytotoxic effect is coupling the radionuclide to a microparticle acting as a carrier vehicle, which could be used for treating disseminated cancers in body cavities. Calcium carbonate may represent a suitable material, as it is biocompatible, biodegradable, and easy to synthesize. In this work, we explored 212Pb-labeling of various CaCO3 microparticles and developed a protocol that can be straightforwardly implemented by clinicians. Vaterite microparticles stabilized by pamidronate were effective as 212Pb carriers; labeling yields of ≥98% were achieved, and 212Pb was strongly retained by the particles in an in vitro stability assessment. Moreover, the amounts of 212Pb reaching the kidneys, liver, spleen, and skeleton of mice following intraperitoneal (i.p.) administration were very low compared to i.p. injection of unbound 212Pb2+, indicating that CaCO3-bound 212Pb exhibited stability when administered intraperitoneally. Therapeutic efficacy was observed in a model of i.p. ovarian cancer for all the tested doses, ranging from 63 to 430 kBq per mouse. Lead-212-labeled CaCO3 microparticles represent a promising candidate for treating intracavitary cancers.
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8
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Stenberg VY, Larsen RH, Ma LW, Peng Q, Juzenas P, Bruland ØS, Juzeniene A. Evaluation of the PSMA-Binding Ligand 212Pb-NG001 in Multicellular Tumour Spheroid and Mouse Models of Prostate Cancer. Int J Mol Sci 2021; 22:ijms22094815. [PMID: 34062920 PMCID: PMC8124365 DOI: 10.3390/ijms22094815] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/27/2021] [Accepted: 04/29/2021] [Indexed: 01/12/2023] Open
Abstract
Radioligand therapy targeting the prostate-specific membrane antigen (PSMA) is rapidly evolving as a promising treatment for metastatic castration-resistant prostate cancer. The PSMA-targeting ligand p-SCN-Bn-TCMC-PSMA (NG001) labelled with 212Pb efficiently targets PSMA-positive cells in vitro and in vivo. The aim of this preclinical study was to evaluate the therapeutic potential of 212Pb-NG001 in multicellular tumour spheroid and mouse models of prostate cancer. The cytotoxic effect of 212Pb-NG001 was tested in human prostate C4-2 spheroids. Biodistribution at various time points and therapeutic effects of different activities of the radioligand were investigated in male athymic nude mice bearing C4-2 tumours, while long-term toxicity was studied in immunocompetent BALB/c mice. The radioligand induced a selective cytotoxic effect in spheroids at activity concentrations of 3–10 kBq/mL. In mice, the radioligand accumulated rapidly in tumours and was retained over 24 h, while it rapidly cleared from nontargeted tissues. Treatment with 0.25, 0.30 or 0.40 MBq of 212Pb-NG001 significantly inhibited tumour growth and improved median survival with therapeutic indexes of 1.5, 2.3 and 2.7, respectively. In BALB/c mice, no signs of long-term radiation toxicity were observed at activities of 0.05 and 0.33 MBq. The obtained results warrant clinical studies to evaluate the biodistribution, therapeutic efficacy and toxicity of 212Pb-NG001.
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Affiliation(s)
- Vilde Yuli Stenberg
- Department of Radiation Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo University Hospital, 0379 Oslo, Norway; (L.-W.M.); (A.J.)
- Department of Research and Development, Nucligen AS, 0379 Oslo, Norway;
- Institute for Clinical Medicine, University of Oslo, 0318 Oslo, Norway;
- Correspondence: ; Tel.: +47-9012-8434
| | | | - Li-Wei Ma
- Department of Radiation Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo University Hospital, 0379 Oslo, Norway; (L.-W.M.); (A.J.)
| | - Qian Peng
- Department of Pathology, The Norwegian Radium Hospital, Oslo University Hospital, 0379 Oslo, Norway; (Q.P.); (P.J.)
| | - Petras Juzenas
- Department of Pathology, The Norwegian Radium Hospital, Oslo University Hospital, 0379 Oslo, Norway; (Q.P.); (P.J.)
| | - Øyvind Sverre Bruland
- Institute for Clinical Medicine, University of Oslo, 0318 Oslo, Norway;
- Department of Oncology, The Norwegian Radium Hospital, Oslo University Hospital, 0379 Oslo, Norway
| | - Asta Juzeniene
- Department of Radiation Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo University Hospital, 0379 Oslo, Norway; (L.-W.M.); (A.J.)
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Improved Formulation of 224Ra-Labeled Calcium Carbonate Microparticles by Surface Layer Encapsulation and Addition of EDTMP. Pharmaceutics 2021; 13:pharmaceutics13050634. [PMID: 33946852 PMCID: PMC8145685 DOI: 10.3390/pharmaceutics13050634] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 04/22/2021] [Accepted: 04/27/2021] [Indexed: 01/01/2023] Open
Abstract
Radium-224-labeled CaCO3 microparticles have been developed to treat peritoneal carcinomatosis. The microparticles function as carriers of 224Ra, facilitating intraperitoneal retention of the alpha-emitting radionuclide. It was necessary to control the size of microparticles in suspension over time and introduce a sterilization process for the clinical use of the radiopharmaceutical. Ethylenediamine tetra(methylene phosphonic acid) (EDTMP) was investigated as a stabilizing additive. The possibility of encapsulating the radiolabeled microparticles with an outer surface layer of CaCO3 for the improved retention of radioactivity by the carrier was studied. This work evaluated these steps of optimization and their effect on radiochemical purity, the biodistribution of radionuclides, and therapeutic efficacy. An EDTMP concentration of >1% (w/w) relative to CaCO3 stabilized the particle size for at least one week. Without EDTMP, the median particle size increased from ~5 µm to ~25 µm immediately after sterilization by autoclaving, and the larger microparticles sedimented rapidly in suspension. The percentage of adsorbed 224Ra progeny 212Pb increased from 56% to 94% at 2.4-2.5% (w/w) EDTMP when the 224Ra-labeled microparticles were layer-encapsulated. The improved formulation also resulted in a suitable biodistribution of radionuclides in mice, as well as a survival benefit for mice with intraperitoneal ovarian or colorectal tumors.
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Napoli E, Bønsdorff TB, Jorstad IS, Bruland ØS, Larsen RH, Westrøm S. Radon-220 diffusion from 224Ra-labeled calcium carbonate microparticles: Some implications for radiotherapeutic use. PLoS One 2021; 16:e0248133. [PMID: 33662039 PMCID: PMC7932545 DOI: 10.1371/journal.pone.0248133] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 02/21/2021] [Indexed: 01/08/2023] Open
Abstract
Alpha-particle emitting radionuclides continue to be the subject of medical research because of their high energy and short range of action that facilitate effective cancer therapies. Radium-224 (224Ra) is one such candidate that has been considered for use in combating micrometastatic disease. In our prior studies, a suspension of 224Ra-labeled calcium carbonate (CaCO3) microparticles was designed as a local therapy for disseminated cancers in the peritoneal cavity. The progenies of 224Ra, of which radon-220 (220Rn) is the first, together contribute three of the four alpha particles in the decay chain. The proximity of the progenies to the delivery site at the time of decay of the 224Ra-CaCO3 microparticles can impact its therapeutic efficacy. In this study, we show that the diffusion of 220Rn was reduced in labeled CaCO3 suspensions as compared with cationic 224Ra solutions, both in air and liquid volumes. Furthermore, free-floating lead-212 (212Pb), which is generated from released 220Rn, had the potential to be re-adsorbed onto CaCO3 microparticles. Under conditions mimicking an in vivo environment, more than 70% of the 212Pb was adsorbed onto the CaCO3 at microparticle concentrations above 1 mg/mL. Further, the diffusion of 220Rn seemed to occur whether the microparticles were labeled by the surface adsorption of 224Ra or if the 224Ra was incorporated into the bulk of the microparticles. The therapeutic benefit of differently labeled 224Ra-CaCO3 microparticles after intraperitoneal administration was similar when examined in mice bearing intraperitoneal ovarian cancer xenografts. In conclusion, both the release of 220Rn and re-adsorption of 212Pb are features that have implications for the radiotherapeutic use of 224Ra-labeled CaCO3 microparticles. The release of 220Rn through diffusion may extend the effective range of alpha-particle dose deposition, and the re-adsorption of the longer lived 212Pb onto the CaCO3 microparticles may enhance the retention of this nuclide in the peritoneal cavity.
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Affiliation(s)
- Elisa Napoli
- Oncoinvent AS, Oslo, Norway
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | | | | | - Øyvind S. Bruland
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway
- Department of Oncology, Oslo University Hospital, Oslo, Norway
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