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Chemarthi VS, Guron G, Shaaban H. A Unique Case of a Patient With Pancreatic Cancer Developing Leptomeningeal Metastases While on Gemcitabine and Nab-Paclitaxel. Cureus 2024; 16:e58139. [PMID: 38738113 PMCID: PMC11088938 DOI: 10.7759/cureus.58139] [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] [Accepted: 04/12/2024] [Indexed: 05/14/2024] Open
Abstract
Brain metastases and leptomeningeal disease are rare with pancreatic cancer. Leptomeningeal disease is a catastrophic complication to have as patients deteriorate rapidly. Patients can present with symptoms of cranial nerve neuropathies, headache, nausea, and focal neurological deficits. We present a patient with metastatic pancreatic cancer who was treated initially with FOLFIRINOX (5-fluorouracil, leucovorin, irinotecan, and oxaliplatin) which resulted in marked clinical and radiologic improvement. However, he started to develop severe peripheral neuropathy and was switched to maintenance gemcitabine and nab-paclitaxel. On this regimen, his systemic disease was well controlled but he developed leptomeningeal carcinomatosis. To our knowledge, this is the first case of leptomeningeal metastases developing in a patient with pancreatic adenocarcinoma while on treatment with gemcitabine and nab-paclitaxel after cessation of FOLFIRINOX. We should maintain high clinical suspicion for leptomeningeal disease in pancreatic cancer, especially when systemic disease is well controlled, as the chemotherapeutic agents may not be crossing the blood-brain barrier effectively contributing to high morbidity and mortality.
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Affiliation(s)
| | - Gunwant Guron
- Hematology and Oncology, Saint Michael's Medical Center/New York Medical College, Newark, USA
| | - Hamid Shaaban
- Hematology and Oncology, Saint Michael's Medical Center/New York Medical College, Newark, USA
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Carrasco-Hernandez J, Ramos-Méndez J, Padilla-Rodal E, Avila-Rodriguez MA. Cellular lethal damage of 64Cu incorporated in mammalian genome evaluated with Monte Carlo methods. Front Med (Lausanne) 2023; 10:1253746. [PMID: 37841004 PMCID: PMC10575761 DOI: 10.3389/fmed.2023.1253746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 09/13/2023] [Indexed: 10/17/2023] Open
Abstract
Purpose Targeted Radionuclide Therapy (TRT) with Auger Emitters (AE) is a technique that allows targeting specific sites on tumor cells using radionuclides. The toxicity of AE is critically dependent on its proximity to the DNA. The aim of this study is to quantify the DNA damage and radiotherapeutic potential of the promising AE radionuclide copper-64 (64Cu) incorporated into the DNA of mammalian cells using Monte Carlo track-structure simulations. Methods A mammalian cell nucleus model with a diameter of 9.3 μm available in TOPAS-nBio was used. The cellular nucleus consisted of double-helix DNA geometrical model of 2.3 nm diameter surrounded by a hydration shell with a thickness of 0.16 nm, organized in 46 chromosomes giving a total of 6.08 giga base-pairs (DNA density of 14.4 Mbp/μm3). The cellular nucleus was irradiated with monoenergetic electrons and radiation emissions from several radionuclides including 111In, 125I, 123I, and 99mTc in addition to 64Cu. For monoenergetic electrons, isotropic point sources randomly distributed within the nucleus were modeled. The radionuclides were incorporated in randomly chosen DNA base pairs at two positions near to the central axis of the double-helix DNA model at (1) 0.25 nm off the central axis and (2) at the periphery of the DNA (1.15 nm off the central axis). For all the radionuclides except for 99mTc, the complete physical decay process was explicitly simulated. For 99mTc only total electron spectrum from published data was used. The DNA Double Strand Breaks (DSB) yield per decay from direct and indirect actions were quantified. Results obtained for monoenergetic electrons and radionuclides 111In, 125I, 123I, and 99mTc were compared with measured and calculated data from the literature for verification purposes. The DSB yields per decay incorporated in DNA for 64Cu are first reported in this work. The therapeutic effect of 64Cu (activity that led 37% cell survival after two cell divisions) was determined in terms of the number of atoms incorporated into the nucleus that would lead to the same DSBs that 100 decays of 125I. Simulations were run until a 2% statistical uncertainty (1 standard deviation) was achieved. Results The behavior of DSBs as a function of the energy for monoenergetic electrons was consistent with published data, the DSBs increased with the energy until it reached a maximum value near 500 eV followed by a continuous decrement. For 64Cu, when incorporated in the genome at evaluated positions (1) and (2), the DSB were 0.171 ± 0.003 and 0.190 ± 0.003 DSB/decay, respectively. The number of initial atoms incorporated into the genome (per cell) for 64Cu that would cause a therapeutic effect was estimated as 3,107 ± 28, that corresponds to an initial activity of 47.1 ± 0.4 × 10-3 Bq. Conclusion Our results showed that TRT with 64Cu has comparable therapeutic effects in cells as that of TRT with radionuclides currently used in clinical practice.
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Affiliation(s)
- Jhonatan Carrasco-Hernandez
- Departamento de Estructura de la Materia, Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - José Ramos-Méndez
- Department of Radiation Oncology, University of California, San Francisco, San Francisco, CA, United States
| | - Elizabeth Padilla-Rodal
- Departamento de Estructura de la Materia, Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Miguel A. Avila-Rodriguez
- Unidad Radiofarmacia-Ciclotrón, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
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Obata H, Ogawa M, Zalutsky MR. DNA Repair Inhibitors: Potential Targets and Partners for Targeted Radionuclide Therapy. Pharmaceutics 2023; 15:1926. [PMID: 37514113 PMCID: PMC10384049 DOI: 10.3390/pharmaceutics15071926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 07/06/2023] [Accepted: 07/07/2023] [Indexed: 07/30/2023] Open
Abstract
The present review aims to explore the potential targets/partners for future targeted radionuclide therapy (TRT) strategies, wherein cancer cells often are not killed effectively, despite receiving a high average tumor radiation dose. Here, we shall discuss the key factors in the cancer genome, especially those related to DNA damage response/repair and maintenance systems for escaping cell death in cancer cells. To overcome the current limitations of TRT effectiveness due to radiation/drug-tolerant cells and tumor heterogeneity, and to make TRT more effective, we propose that a promising strategy would be to target the DNA maintenance factors that are crucial for cancer survival. Considering their cancer-specific DNA damage response/repair ability and dysregulated transcription/epigenetic system, key factors such as PARP, ATM/ATR, amplified/overexpressed transcription factors, and DNA methyltransferases have the potential to be molecular targets for Auger electron therapy; moreover, their inhibition by non-radioactive molecules could be a partnering component for enhancing the therapeutic response of TRT.
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Affiliation(s)
- Honoka Obata
- Department of Advanced Nuclear Medicine Sciences, National Institutes for Quantum Science and Technology (QST), 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
- Department of Molecular Imaging and Theranostics, National Institutes for Quantum Science and Technology (QST), 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
- Departments of Radiology and Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA
- Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-ku, Sapporo 060-0812, Japan
| | - Mikako Ogawa
- Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-ku, Sapporo 060-0812, Japan
| | - Michael R Zalutsky
- Departments of Radiology and Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA
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Future Prospective of Radiopharmaceuticals from Natural Compounds Using Iodine Radioisotopes as Theranostic Agents. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27228009. [PMID: 36432107 PMCID: PMC9694974 DOI: 10.3390/molecules27228009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 11/06/2022] [Accepted: 11/11/2022] [Indexed: 11/19/2022]
Abstract
Natural compounds provide precursors with various pharmacological activities and play an important role in discovering new chemical entities, including radiopharmaceuticals. In the development of new radiopharmaceuticals, iodine radioisotopes are widely used and interact with complex compounds including natural products. However, the development of radiopharmaceuticals from natural compounds with iodine radioisotopes has not been widely explored. This review summarizes the development of radiopharmaceuticals from natural compounds using iodine radioisotopes in the last 10 years, as well as discusses the challenges and strategies to improve future discovery of radiopharmaceuticals from natural resources. Literature research was conducted via PubMed, from which 32 research articles related to the development of natural compounds labeled with iodine radioisotopes were reported. From the literature, the challenges in developing radiopharmaceuticals from natural compounds were the purity and biodistribution. Despite the challenges, the development of radiopharmaceuticals from natural compounds is a golden opportunity for nuclear medicine advancement.
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Iwatsuka K, Kikuta D, Shibuya H, Ogawa M, Gotoda T, Moriyama M, Nakagawara H, Hemmi A, Yamao K. Treatment Outcome of Nab-paclitaxel Plus Gemcitabine for Leptomeningeal Carcinomatosis from Pancreatic Ductal Adenocarcinoma: An Autopsy Case Report. Intern Med 2021; 60:3743-3748. [PMID: 34148945 PMCID: PMC8710377 DOI: 10.2169/internalmedicine.4456-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
A 57-year-old woman with a sudden-onset seizure was hospitalized. Brain magnetic resonance imaging findings led to a suspicion of leptomeningeal carcinomatosis (LMC) without a brain parenchymal tumor, and abdominal computed tomography showed a tumor in the pancreatic tail. Endoscopic ultrasonography-guided fine needle aspiration of the pancreatic mass revealed adenocarcinoma. Therefore, LMC from pancreatic ductal adenocarcinoma was strongly suspected. She received three courses of nab-paclitaxel plus gemcitabine and whole-brain radiation. Shortly thereafter, she developed a severe consciousness impediment and died. A pathological autopsy showed adenocarcinoma in a wide area of the leptomeninges.
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Affiliation(s)
- Kunio Iwatsuka
- Division of Gastroenterology and Hepatology, Department of Medicine, Nihon University School of Medicine Graduate School of Medicine, Japan
| | - Daiichiro Kikuta
- Division of Gastroenterology and Hepatology, Department of Medicine, Nihon University School of Medicine Graduate School of Medicine, Japan
| | - Hitoshi Shibuya
- Division of Gastroenterology and Hepatology, Department of Medicine, Nihon University School of Medicine Graduate School of Medicine, Japan
| | - Masahiro Ogawa
- Division of Gastroenterology and Hepatology, Department of Medicine, Nihon University School of Medicine Graduate School of Medicine, Japan
| | - Takuji Gotoda
- Division of Gastroenterology and Hepatology, Department of Medicine, Nihon University School of Medicine Graduate School of Medicine, Japan
| | - Mitsuhiko Moriyama
- Division of Gastroenterology and Hepatology, Department of Medicine, Nihon University School of Medicine Graduate School of Medicine, Japan
| | | | - Akihiro Hemmi
- Division of Pathology, Nihon University School of Medicine Graduate School of Medicine, Japan
| | - Kenji Yamao
- Department of Gastroenterology, Narita Memorial Hospital, Japan
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Verger E, Cheng J, de Santis V, Iafrate M, Jackson JA, Imberti C, Fruhwirth GO, Blower PJ, Ma MT, Burnham DR, Terry SYA. Validation of the plasmid study to relate DNA damaging effects of radionuclides to those from external beam radiotherapy. Nucl Med Biol 2021; 100-101:36-43. [PMID: 34153932 PMCID: PMC7611685 DOI: 10.1016/j.nucmedbio.2021.06.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 03/31/2021] [Accepted: 06/10/2021] [Indexed: 12/29/2022]
Abstract
INTRODUCTION The biological consequences of absorbed radiation doses are ill-defined for radiopharmaceuticals, unlike for external beam radiotherapy (EBRT). A reliable assay that assesses the biological consequences of any radionuclide is much needed. Here, we evaluated the cell-free plasmid DNA assay to determine the relative biological effects of radionuclides such as Auger electron-emitting [67Ga]GaCl3 or [111In]InCl3 compared to EBRT. METHODS Supercoiled pBR322 plasmid DNA (1.25 or 5 ng/μL) was incubated with 0.5 or 1 MBq [67Ga]GaCl3 or [111In]InCl3 for up to 73 h or was exposed to EBRT (137Cs; 5 Gy/min; 0-40 Gy). The induction of relaxed and linear plasmid DNA, representing single and double strand breaks, respectively, was assessed by gel electrophoresis. Chelated forms of 67Ga were also investigated using DOTA and THP. Topological conversion rates for supercoiled-to-relaxed (ksrx) or relaxed-to-linear (krlx) DNA were obtained by fitting a kinetic model. RESULTS DNA damage increased both with EBRT dose and incubation time for [67Ga]GaCl3 and [111In]InCl3. Damage caused by [67Ga]GaCl3 decreased when chelated. [67Ga]GaCl3 proved more damaging than [111In]InCl3; 1.25 ng/μL DNA incubated with 0.5 MBq [67Ga]GaCl3 for 2 h led to a 70% decrease of intact plasmid DNA as opposed to only a 19% decrease for [111In]InCl3. For both EBRT and radionuclides, conversion rates were slower for 5 ng/μL than 1.25 ng/μL plasmid DNA. DNA damage caused by 1 Gy EBRT was the equivalent to damage caused by 0.5 MBq unchelated [67Ga]GaCl3 and [111In]InCl3 after 2.05 ± 0.36 and 9.3 ± 0.77 h of incubation, respectively. CONCLUSIONS This work has highlighted the power of the plasmid DNA assay for a rapid determination of the relative biological effects of radionuclides compared to external beam radiotherapy. It is envisaged this approach will enable the systematic assessment of imaging and therapeutic radionuclides, including Auger electron-emitters, to further inform radiopharmaceutical design and application.
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Affiliation(s)
- Elise Verger
- School of Biomedical Engineering and Imaging Sciences, King's College London, St. Thomas' Hospital, London SE1 7EH, United Kingdom
| | - Jordan Cheng
- School of Biomedical Engineering and Imaging Sciences, King's College London, St. Thomas' Hospital, London SE1 7EH, United Kingdom
| | - Vittorio de Santis
- School of Biomedical Engineering and Imaging Sciences, King's College London, St. Thomas' Hospital, London SE1 7EH, United Kingdom
| | - Madeleine Iafrate
- School of Biomedical Engineering and Imaging Sciences, King's College London, St. Thomas' Hospital, London SE1 7EH, United Kingdom
| | - Jessica A Jackson
- School of Biomedical Engineering and Imaging Sciences, King's College London, St. Thomas' Hospital, London SE1 7EH, United Kingdom
| | - Cinzia Imberti
- School of Biomedical Engineering and Imaging Sciences, King's College London, St. Thomas' Hospital, London SE1 7EH, United Kingdom
| | - Gilbert O Fruhwirth
- School of Biomedical Engineering and Imaging Sciences, King's College London, St. Thomas' Hospital, London SE1 7EH, United Kingdom; Comprehensive Cancer Centre, School of Cancer and Pharmaceutical Sciences, King's College London, Guy's Hospital Campus, London SE1 1UL, United Kingdom
| | - Philip J Blower
- School of Biomedical Engineering and Imaging Sciences, King's College London, St. Thomas' Hospital, London SE1 7EH, United Kingdom
| | - Michelle T Ma
- School of Biomedical Engineering and Imaging Sciences, King's College London, St. Thomas' Hospital, London SE1 7EH, United Kingdom
| | - Daniel R Burnham
- Single Molecule Imaging of Genome Duplication and Maintenance Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Samantha Y A Terry
- School of Biomedical Engineering and Imaging Sciences, King's College London, St. Thomas' Hospital, London SE1 7EH, United Kingdom.
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Wilson T, Pirovano G, Xiao G, Samuels Z, Roberts S, Viray T, Guru N, Zanzonico P, Gollub M, Pillarsetty NVK, Reiner T, Bargonetti J. PARP-Targeted Auger Therapy in p53 Mutant Colon Cancer Xenograft Mouse Models. Mol Pharm 2021; 18:3418-3428. [PMID: 34318678 DOI: 10.1021/acs.molpharmaceut.1c00323] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Despite Auger electrons being highly appealing due to their short-range and high linear energy transfer to surrounding tissues, the progress in the field has been limited due to the challenge in delivering a therapeutic dose within the close proximity of cancer cell's DNA. Here, we demonstrate that the PARP inhibitor 123I-MAPi is a viable agent for the systemic administration and treatment of p53 mutant cancers. Significantly, minimal off-site toxicity was observed in mice administered with up to 74 MBq of 127I-PARPi. Taken together, these results lay the foundation for future clinical evaluation and broader preclinical investigations. By harnessing the scaffold of the PARP inhibitor Olaparib, we were able to deliver therapeutic levels of Auger radiation to the site of human colorectal cancer xenograft tumors after systemic administration. In-depth toxicity studies analyzed blood chemistry levels and markers associated with specific organ toxicity. Finally, p53+/+ and p53-/- human colorectal cancer cell lines were evaluated for the ability of 123I-MAPi to induce tumor growth delay. Toxicity studies demonstrate that both 123I-MAPi and its stable isotopologue, 127I-PARPi, have no significant off-site toxicity when administered systemically. Analysis following 123I-MAPi treatment confirmed its ability to induce DNA damage at the site of xenograft tumors when administered systemically. Finally, we demonstrate that 123I-MAPi generates a therapeutic response in p53-/-, but not p53+/+, subcutaneous xenograft tumors in mouse models. Taken together, these results represent the first example of a PARP Auger theranostic agent capable of delivering a therapeutic dose to xenograft human colorectal cancer tumors upon systemic administration without causing significant toxicity to surrounding mouse organs. Moreover, it suggests that a PARP Auger theranostic can act as a targeted therapeutic for cancers with mutated p53 pathways. This landmark goal paves the way for clinical evaluation of 123I-MAPi for pan cancer therapeutics.
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Affiliation(s)
- Thomas Wilson
- Department of Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
| | - Giacomo Pirovano
- Department of Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
| | - Gu Xiao
- Department of Biological Sciences Hunter College, City University of New York, New York, New York 10065, United States
| | - Zachary Samuels
- Department of Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
| | - Sheryl Roberts
- Department of Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
| | - Tara Viray
- Department of Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
| | - Navjot Guru
- Department of Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
| | - Pat Zanzonico
- Department of Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
| | - Marc Gollub
- Department of Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States.,Department of Radiology, Weill Cornell Medical College, New York, New York 10065, United States
| | - Naga Vara Kishore Pillarsetty
- Department of Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States.,Department of Radiology, Weill Cornell Medical College, New York, New York 10065, United States
| | - Thomas Reiner
- Department of Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States.,Department of Radiology, Weill Cornell Medical College, New York, New York 10065, United States.,Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, United States
| | - Jill Bargonetti
- Department of Biological Sciences Hunter College, City University of New York, New York, New York 10065, United States.,The Graduate Center Biology and Biochemistry PhD Program of City University of New York, New York, New York 10016, United States.,Department of Cell and Developmental Biology, Weill Cornell Medical College, New York, New York 10065, United States
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Moradi MS, Bidabadi BS. Assessment of Single-and Double-Strand Breaks in DNA Induced by Auger Electrons of Radioisotopes Used in Diagnostic and Therapeutic Applications. J Med Phys 2021; 45:240-248. [PMID: 33953500 PMCID: PMC8074716 DOI: 10.4103/jmp.jmp_79_19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Revised: 12/02/2020] [Accepted: 12/02/2020] [Indexed: 11/30/2022] Open
Abstract
Introduction: Most of the radionuclides that are used for diagnostic purposes emit Auger electrons and can thus cause damage to the DNA molecule on a nanometer scale. Therefore, the nanodosimetric calculation of these radioisotopes is necessary to achieve better understanding on their effects. Aim: The aim of this study was to calculate the mean number of DNA strand breaks (single-strand breaks and double-strand breaks) caused by direct and indirect effects for six widely used Auger electron-emitting diagnostic radioisotopes, including 123I, 125I, 99mTc, 67Ga, 201Tl, 111In and two therapeutic radioisotopes of 131I(beta + Auger + CK emitter) and 211At(alpha + Auger + CK emitter). Materials and Methods: Geant4-DNA simulation tool was used to evaluate the effects of Auger electrons, beta and alpha particles of these radioisotopes on DNA molecules. Two different DNA molecule geometric models were simulated and the results of these two models were compared with each other as well as with the results of previous studies. Results and Conclusion: The results showed that the geometric shape of the sugar-phosphate groups may have a significant effect on the number of single-strand breaks (SSBs) and double-strand breaks (DSBs) of the DNA molecule. Among the most widely used diagnostic radioisotopes, 201Tl and 125I, had the greatest impact on the number of SSBs and DSBs, respectively, while therapeutic radioisotope of 131I almost had no effect, therapeutic radioisotope of 211At had the moderate effect on the number of breaks in the DNA chain.
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Affiliation(s)
- Mahdi Seifi Moradi
- Department of Nuclear Engineering, Faculty of Physics, University of Isfahan, Isfahan, Iran
| | - Babak Shirani Bidabadi
- Department of Nuclear Engineering, Faculty of Physics, University of Isfahan, Isfahan, Iran
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In Vitro Evaluation of No-Carrier-Added Radiolabeled Cisplatin ([ 189, 191Pt]cisplatin) Emitting Auger Electrons. Int J Mol Sci 2021; 22:ijms22094622. [PMID: 33924843 PMCID: PMC8124180 DOI: 10.3390/ijms22094622] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 04/20/2021] [Accepted: 04/26/2021] [Indexed: 01/20/2023] Open
Abstract
Due to their short-range (2–500 nm), Auger electrons (Auger e−) have the potential to induce nano-scale physiochemical damage to biomolecules. Although DNA is the primary target of Auger e−, it remains challenging to maximize the interaction between Auger e− and DNA. To assess the DNA-damaging effect of Auger e− released as close as possible to DNA without chemical damage, we radio-synthesized no-carrier-added (n.c.a.) [189, 191Pt]cisplatin and evaluated both its in vitro properties and DNA-damaging effect. Cellular uptake, intracellular distribution, and DNA binding were investigated, and DNA double-strand breaks (DSBs) were evaluated by immunofluorescence staining of γH2AX and gel electrophoresis of plasmid DNA. Approximately 20% of intracellular radio-Pt was in a nucleus, and about 2% of intra-nucleus radio-Pt bound to DNA, although uptake of n.c.a. radio-cisplatin was low (0.6% incubated dose after 25-h incubation), resulting in the frequency of cells with γH2AX foci was low (1%). Nevertheless, some cells treated with radio-cisplatin had γH2AX aggregates unlike non-radioactive cisplatin. These findings suggest n.c.a. radio-cisplatin binding to DNA causes severe DSBs by the release of Auger e− very close to DNA without chemical damage by carriers. Efficient radio-drug delivery to DNA is necessary for successful clinical application of Auger e−.
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Synthesis of no-carrier-added [ 188, 189, 191Pt]cisplatin from a cyclotron produced 188, 189, 191PtCl 42- complex. Sci Rep 2021; 11:8140. [PMID: 33854142 PMCID: PMC8046966 DOI: 10.1038/s41598-021-87576-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 03/24/2021] [Indexed: 01/01/2023] Open
Abstract
We developed a novel method for production of no-carrier-added (n.c.a.) [188, 189, 191Pt]PtIICl42- from an Ir target material, and then synthesized n.c.a. [*Pt]cis-[PtIICl2(NH3)2] ([*Pt]cisplatin) from [*Pt]PtIICl42-. [*Pt]PtIICl42- was prepared as a synthetic precursor of n.c.a. *Pt complex by a combination of resin extraction and anion-exchange chromatography after the selective reduction of IrIVCl62- with ascorbic acid. The ligand-substitution reaction of Cl with NH3 was promoted by treating n.c.a. [*Pt]PtIICl42- with excess NH3 and heating the reaction mixture, and n.c.a. [*Pt]cisplatin was successfully produced without employing precipitation routes. After this treatment, [*Pt]cisplatin was isolated through preparative HPLC with a radiochemical purity of 99 + % at the end of synthesis (EOS).
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11
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Auger: The future of precision medicine. Nucl Med Biol 2021; 96-97:50-53. [PMID: 33831745 DOI: 10.1016/j.nucmedbio.2021.03.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 03/09/2021] [Accepted: 03/09/2021] [Indexed: 12/11/2022]
Abstract
First reported by Lise Meitner in 1922 and independently by Pierre Auger in 1923, the Auger effect has been explored as a potential source for targeted radiotherapy. The Auger effect is based on the emission of a low energy electron (typically <25 keV) from an atom post electron capture (EC), internal conversion (IC), or incident X-rays excitation. This phenomenon can cause the emission of a primary electron and multiple electron tracks typically in the nearest proximity of the emission site (2-500 nm). The short range of the emitted Auger cascade results in medium/high levels of linear energy transfer (4-26 keV/μm) exerted on the surrounding tissue. This property makes Auger emitters the ideal candidates for delivering high levels of targeted radiation to a specific target with dimensions comparable to, for example, the DNA. By using a targeting vector such as a small molecule, peptide or antibody, one has the potential of delivering high levels of radiation to tumor specific biomarkers while circumventing off-site toxicity in healthy cells; a challenge which is harder to overcome when using other, longer range sources of radiation such as beta and alpha emitting radionuclides. Several reviews on Auger emitters have been published over the years with two recent examples. For these reviews and others, we support their analysis and therefore to avoid simple repetition, this commentary will seek to address additional aspects and viewpoints. Specifically, we will focus on those most promising preclinical and clinical studies using small molecules, peptides, antibodies and how these studies may serve as a template for future studies.
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Mahdi SM, Babak SB. Dosimetry study on Auger electron-emitting nuclear medicine radioisotopes in micrometer and nanometer scales using Geant4-DNA simulation. Int J Radiat Biol 2020; 96:1452-1465. [DOI: 10.1080/09553002.2020.1820608] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Abstract
Radiopharmaceutical therapy (RPT) is emerging as a safe and effective targeted approach to treating many types of cancer. In RPT, radiation is systemically or locally delivered using pharmaceuticals that either bind preferentially to cancer cells or accumulate by physiological mechanisms. Almost all radionuclides used in RPT emit photons that can be imaged, enabling non-invasive visualization of the biodistribution of the therapeutic agent. Compared with almost all other systemic cancer treatment options, RPT has shown efficacy with minimal toxicity. With the recent FDA approval of several RPT agents, the remarkable potential of this treatment is now being recognized. This Review covers the fundamental properties, clinical development and associated challenges of RPT. Radiopharmaceutical therapy is emerging as a safe and effective approach for the treatment of cancer, offering several advantages over existing therapeutic strategies. Here, Sgouros and colleagues provide an overview of the fundamental properties of radiopharmaceutical therapy, discuss agents in use and in clinical development and highlight the associated translational challenges.
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Ceccon G, Wollring M, Brunn A, Deckert M, Waldschmidt D, Fink GR, Galldiks N. Leptomeningeal Carcinomatosis in a Patient with Pancreatic Cancer Responding to Nab-Paclitaxel plus Gemcitabine. Case Rep Oncol 2020; 13:35-42. [PMID: 32095126 PMCID: PMC7011711 DOI: 10.1159/000504697] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 11/05/2019] [Indexed: 12/12/2022] Open
Abstract
Leptomeningeal carcinomatosis is an extremely rare, but devastating complication in pancreatic cancer patients with a poor prognosis despite multimodal treatment. We present a 51-year-old male patient with the very rare condition of leptomeningeal carcinomatosis originating from pancreatic cancer. He presented to our hospital with severe headache and neck stiffness 30 months after systemic chemotherapy. Cerebral and spinal MRI as well as cerebrospinal fluid examination confirmed the diagnosis of leptomeningeal carcinomatosis. The patient responded to gemcitabine plus nab-paclitaxel in terms of elimination of tumor cells from the CSF and concurrent clinical improvement for 3 months. The observed findings suggest that the combination of gemcitabine plus nab-paclitaxel is potentially effective in affected cerebrospinal fluid of pancreatic carcinoma patients.
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Affiliation(s)
- Garry Ceccon
- Department of Neurology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Michael Wollring
- Department of Neurology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Anna Brunn
- Department of Neuropathology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Martina Deckert
- Department of Neuropathology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Dirk Waldschmidt
- Department of Hepato- and Gastroenterology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany.,Center of Integrated Oncology (CIO), Universities of Aachen, Bonn, Cologne, and Duesseldorf, Cologne, Germany
| | - Gereon R Fink
- Department of Neurology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany.,Institute of Neuroscience and Medicine (INM-3), Forschungszentrum Jülich, Jülich, Germany
| | - Norbert Galldiks
- Department of Neurology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany.,Institute of Neuroscience and Medicine (INM-3), Forschungszentrum Jülich, Jülich, Germany.,Center of Integrated Oncology (CIO), Universities of Aachen, Bonn, Cologne, and Duesseldorf, Cologne, Germany
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15
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Ku A, Facca VJ, Cai Z, Reilly RM. Auger electrons for cancer therapy - a review. EJNMMI Radiopharm Chem 2019; 4:27. [PMID: 31659527 PMCID: PMC6800417 DOI: 10.1186/s41181-019-0075-2] [Citation(s) in RCA: 159] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 08/28/2019] [Indexed: 12/23/2022] Open
Abstract
Background Auger electrons (AEs) are very low energy electrons that are emitted by radionuclides that decay by electron capture (e.g. 111In, 67Ga, 99mTc, 195mPt, 125I and 123I). This energy is deposited over nanometre-micrometre distances, resulting in high linear energy transfer (LET) that is potent for causing lethal damage in cancer cells. Thus, AE-emitting radiotherapeutic agents have great potential for treatment of cancer. In this review, we describe the radiobiological properties of AEs, their radiation dosimetry, radiolabelling methods, and preclinical and clinical studies that have been performed to investigate AEs for cancer treatment. Results AEs are most lethal to cancer cells when emitted near the cell nucleus and especially when incorporated into DNA (e.g. 125I-IUdR). AEs cause DNA damage both directly and indirectly via water radiolysis. AEs can also kill targeted cancer cells by damaging the cell membrane, and kill non-targeted cells through a cross-dose or bystander effect. The radiation dosimetry of AEs considers both organ doses and cellular doses. The Medical Internal Radiation Dose (MIRD) schema may be applied. Radiolabelling methods for complexing AE-emitters to biomolecules (antibodies and peptides) and nanoparticles include radioiodination (125I and 123I) or radiometal chelation (111In, 67Ga, 99mTc). Cancer cells exposed in vitro to AE-emitting radiotherapeutic agents exhibit decreased clonogenic survival correlated at least in part with unrepaired DNA double-strand breaks (DSBs) detected by immunofluorescence for γH2AX, and chromosomal aberrations. Preclinical studies of AE-emitting radiotherapeutic agents have shown strong tumour growth inhibition in vivo in tumour xenograft mouse models. Minimal normal tissue toxicity was found due to the restricted toxicity of AEs mostly on tumour cells targeted by the radiotherapeutic agents. Clinical studies of AEs for cancer treatment have been limited but some encouraging results were obtained in early studies using 111In-DTPA-octreotide and 125I-IUdR, in which tumour remissions were achieved in several patients at administered amounts that caused low normal tissue toxicity, as well as promising improvements in the survival of glioblastoma patients with 125I-mAb 425, with minimal normal tissue toxicity. Conclusions Proof-of-principle for AE radiotherapy of cancer has been shown preclinically, and clinically in a limited number of studies. The recent introduction of many biologically-targeted therapies for cancer creates new opportunities to design novel AE-emitting agents for cancer treatment. Pierre Auger did not conceive of the application of AEs for targeted cancer treatment, but this is a tremendously exciting future that we and many other scientists in this field envision.
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Affiliation(s)
- Anthony Ku
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, ON, Canada
| | - Valerie J Facca
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, ON, Canada
| | - Zhongli Cai
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, ON, Canada
| | - Raymond M Reilly
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, ON, Canada. .,Department of Medical Imaging, University of Toronto, Toronto, ON, Canada. .,Joint Department of Medical Imaging and Toronto General Research Institute, University Health Network, Toronto, ON, Canada. .,Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College St., Toronto, ON, M5S 3M2, Canada.
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16
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Micro-dosimetry calculation of Auger-electron-emitting radionuclides mostly used in nuclear medicine using GEANT4-DNA. Appl Radiat Isot 2018; 141:73-79. [DOI: 10.1016/j.apradiso.2018.08.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 08/20/2018] [Accepted: 08/21/2018] [Indexed: 11/20/2022]
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17
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Johnson WR, Theeler BJ, Van Echo D, Young P, Kwok M. Treatment of Leptomeningeal Carcinomatosis in a Patient with Metastatic Pancreatic Cancer: A Case Report and Review of the Literature. Case Rep Oncol 2018; 11:281-288. [PMID: 29867436 PMCID: PMC5981627 DOI: 10.1159/000489085] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 04/09/2018] [Indexed: 01/05/2023] Open
Abstract
Pancreatic cancer is the fourth leading cause of cancer-related death with a median survival of 3–11 months when metastatic. We present a patient with metastatic pancreatic cancer and an exceptional response to initial systemic chemotherapy with FOLFIRINOX (fluorouracil, leucovorin, irinotecan, and oxaliplatin). Despite evidence of disease control on body imaging, he developed symptomatic leptomeningeal disease and brain metastases 29 months into treatment. He received aggressive treatment with capecitabine and irinotecan, intrathecal topotecan, and eventually bevacizumab. He did well for 36 weeks on this regimen until developing sepsis. This patient significantly outlived his expected survival and, moreover, did so with very good quality of life. This case demonstrates the natural history of pancreatic cancer progressing to involve the central nervous system when systemic disease is otherwise responsive to chemotherapy. It is the first case to demonstrate the potential effectiveness of intrathecal topotecan in combination with systemic chemotherapy for the treatment of leptomeningeal metastases of pancreatic cancer.
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Affiliation(s)
| | - Brett J Theeler
- Walter Reed National Military Medical Center, Bethesda, Maryland, USA
| | - David Van Echo
- Walter Reed National Military Medical Center, Bethesda, Maryland, USA
| | - Patrick Young
- Walter Reed National Military Medical Center, Bethesda, Maryland, USA
| | - Mary Kwok
- Walter Reed National Military Medical Center, Bethesda, Maryland, USA
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18
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Shinohara A, Hanaoka H, Sakashita T, Sato T, Yamaguchi A, Ishioka NS, Tsushima Y. Rational evaluation of the therapeutic effect and dosimetry of auger electrons for radionuclide therapy in a cell culture model. Ann Nucl Med 2017; 32:114-122. [PMID: 29238922 DOI: 10.1007/s12149-017-1225-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 12/07/2017] [Indexed: 01/09/2023]
Abstract
OBJECTIVE Radionuclide therapy with low-energy auger electron emitters may provide high antitumor efficacy while keeping the toxicity to normal organs low. Here we evaluated the usefulness of an auger electron emitter and compared it with that of a beta emitter for tumor treatment in in vitro models and conducted a dosimetry simulation using radioiodine-labeled metaiodobenzylguanidine (MIBG) as a model compound. METHODS We evaluated the cellular uptake of 125I-MIBG and the therapeutic effects of 125I- and 131I-MIBG in 2D and 3D PC-12 cell culture models. We used a Monte Carlo simulation code (PHITS) to calculate the absorbed radiation dose of 125I or 131I in computer simulation models for 2D and 3D cell cultures. In the dosimetry calculation for the 3D model, several distribution patterns of radionuclide were applied. RESULTS A higher cumulative dose was observed in the 3D model due to the prolonged retention of MIBG compared to the 2D model. However, 125I-MIBG showed a greater therapeutic effect in the 2D model compared to the 3D model (respective EC50 values in the 2D and 3D models: 86.9 and 303.9 MBq/cell), whereas 131I-MIBG showed the opposite result (respective EC50 values in the 2D and 3D models: 49.4 and 30.2 MBq/cell). The therapeutic effect of 125I-MIBG was lower than that of 131I-MIBG in both models, but the radionuclide-derived difference was smaller in the 2D model. The dosimetry simulation with PHITS revealed the influence of the radiation quality, the crossfire effect, radionuclide distribution, and tumor shape on the absorbed dose. Application of the heterogeneous distribution series dramatically changed the radiation dose distribution of 125I-MIBG, and mitigated the difference between the estimated and measured therapeutic effects of 125I-MIBG. CONCLUSIONS The therapeutic effect of 125I-MIBG was comparable to that of 131I-MIBG in the 2D model, but the efficacy was inferior to that of 131I-MIBG in the 3D model, since the crossfire effect is negligible and the homogeneous distribution of radionuclides was insufficient. Thus, auger electrons would be suitable for treating small-sized tumors. The design of radiopharmaceuticals with auger electron emitters requires particularly careful consideration of achieving a homogeneous distribution of the compound in the tumor.
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Affiliation(s)
- Ayaka Shinohara
- Department of Heavy Ion Beam Medical Physics and Biology, Gunma University Graduate School of Medicine, 3-39-22 Showa, Maebashi, 371-8511, Japan
| | - Hirofumi Hanaoka
- Department of Bioimaging Information Analysis, Gunma University Graduate School of Medicine, 3-39-22 Showa, Maebashi, 371-8511, Japan.
| | - Tetsuya Sakashita
- Quantum Beam Science Research Directorate, National Institutes for Quantum and Radiological Science and Technology, 1233 Watanuki-machi, Takasaki, 370-1292, Japan
| | - Tatsuhiko Sato
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, 319-1195, Japan
| | - Aiko Yamaguchi
- Department of Bioimaging Information Analysis, Gunma University Graduate School of Medicine, 3-39-22 Showa, Maebashi, 371-8511, Japan
| | - Noriko S Ishioka
- Quantum Beam Science Research Directorate, National Institutes for Quantum and Radiological Science and Technology, 1233 Watanuki-machi, Takasaki, 370-1292, Japan
| | - Yoshito Tsushima
- Department of Diagnostic Radiology and Nuclear Medicine, Gunma University Graduate School of Medicine, 3-39-22 Showa, Maebashi, 371-8511, Japan.,Research Program for Diagnostic and Molecular Imaging, Division of Integrated Oncology Research, Gunma University Initiative for Advanced Research (GIAR), Gunma University Graduate School of Medicine, 3-39-22 Showa, Maebashi, 371-8511, Japan
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19
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Rezaee M, Hill RP, Jaffray DA. The Exploitation of Low-Energy Electrons in Cancer Treatment. Radiat Res 2017; 188:123-143. [PMID: 28557630 DOI: 10.1667/rr14727.1] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Given the distinct characteristics of low-energy electrons (LEEs), particularly at energies less than 30 eV, they can be applied to a wide range of therapeutic modalities to improve cancer treatment. LEEs have been shown to efficiently produce complex molecular damage resulting in substantial cellular toxicities. Since LEEs are produced in copious amounts from high-energy radiation beam, including photons, protons and ions; the control of LEE distribution can potentially enhance the therapeutic radio of such beams. LEEs can play a substantial role in the synergistic effect between radiation and chemotherapy, particularly halogenated and platinum-based anticancer drugs. Radiosensitizing entities containing atoms of high atomic number such as gold nanoparticles can be a source of LEE production if high-energy radiation interacts with them. This can provide a high local density of LEEs in a cell and produce cellular toxicity. Auger-electron-emitting radionuclides also create a high number of LEEs in each decay, which can induce lethal damage in a cell. Exploitation of LEEs in cancer treatment, however, faces a few challenges, such as dosimetry of LEEs and selective delivery of radiosensitizing and chemotherapeutic molecules close to cellular targets. This review first discusses the rationale for utilizing LEEs in cancer treatment by explaining their mechanism of action, describes theoretical and experimental studies at the molecular and cellular levels, then discusses strategies for achieving modification of the distribution and effectiveness of LEEs in cancerous tissue and their associated clinical benefit.
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Affiliation(s)
- Mohammad Rezaee
- Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Ontario Cancer Institute and Campbell Family Institute for Cancer Research and Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada
| | - Richard P Hill
- Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Ontario Cancer Institute and Campbell Family Institute for Cancer Research and Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada
| | - David A Jaffray
- Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Ontario Cancer Institute and Campbell Family Institute for Cancer Research and Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada
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20
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Raghavan R, Howell RW, Zalutsky MR. A model for optimizing delivery of targeted radionuclide therapies into resection cavity margins for the treatment of primary brain cancers. Biomed Phys Eng Express 2017; 3. [PMID: 29081990 DOI: 10.1088/2057-1976/aa6db9] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Radionuclides conjugated to molecules that bind specifically to cancer cells are of great interest as a means to increase the specificity of radiotherapy. Currently, the methods to disseminate these targeted radiotherapeutics have been either systemic delivery or by bolus injection into the tumor or tumor resection cavity. Herein we model a potentially more efficient method of delivery, namely pressure-driven fluid flow, called convection-enhanced delivery (CED), where a device infuses the molecules in solution (or suspension) directly into the tissue of interest. In particular, we focus on the setting of primary brain cancer after debulking surgery, where the tissue margins surrounding the surgical resection cavity are infiltrated with tumor cells and the most frequent sites of tumor recurrence. We develop the combination of fluid flow, chemical kinetics, and radiation dose models needed to examine such protocols. We focus on Auger electron-emitting radionuclides (e.g. 67Ga, 77Br, 111In, 125I, 123I, 193mPt, 195mPt) whose short range makes them ideal for targeted therapy in this setting of small foci of tumor spread within normal tissue. By solving these model equations, we confirm that a CED protocol is promising in allowing sufficient absorbed dose to destroy cancer cells with minimal absorbed dose to normal cells at clinically feasible activity levels. We also show that Auger emitters are ideal for this purpose while the longer range alpha particle emitters fail to meet criteria for effective therapy (as neither would energetic beta particle emitters). The model is used with simplified assumptions on the geometry and homogeneity of brain tissue to allow semi-analytic solutions to be displayed, and with the purpose of a first examination of this new delivery protocol proposed for radionuclide therapy. However, we emphasize that it is immediately extensible to personalized therapy treatment planning as we have previously shown for conventional CED, at the price of requiring a fully numerical computerized approach.
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Affiliation(s)
- Raghu Raghavan
- Therataxis, LLC, JHU Eastern Complex, Suite B305, 1101 E. 33rd St., Baltimore MD 21218, United States of America
| | - Roger W Howell
- Division of Radiation Research, Department of Radiology, New Jersey Medical School Cancer Center. Rutgers, The State Univeristy of New Jersey, 205 S. Orange Ave, Newark, NJ 07103, United States of America
| | - Michael R Zalutsky
- Department of Radiology, Duke University Medical Center, 311 Research Drive, Durham, NC27710, United States of America
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21
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Thisgaard H, Halle B, Aaberg-Jessen C, Olsen BB, Therkelsen ASN, Dam JH, Langkjær N, Munthe S, Någren K, Høilund-Carlsen PF, Kristensen BW. Highly Effective Auger-Electron Therapy in an Orthotopic Glioblastoma Xenograft Model using Convection-Enhanced Delivery. Theranostics 2016; 6:2278-2291. [PMID: 27924163 PMCID: PMC5135448 DOI: 10.7150/thno.15898] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 08/30/2016] [Indexed: 12/13/2022] Open
Abstract
Glioblastoma, the most common and malignant primary brain tumor, always recurs after standard treatment. Therefore, promising new therapeutic approaches are needed. Short-range Auger-electron-emitters carry the ability of causing highly damaging radiation effects in cells. The aim of this study was to test the effect of [125I]5-Iodo-2'-deoxyuridine (125I-UdR, a radioactive Auger-electron-emitting thymidine analogue) Auger-therapy on immature glioblastoma spheroid cultures and orthotopic xenografted glioblastoma-bearing rats, the latter by means of convection-enhanced delivery (CED). Moreover, we aimed to determine if the therapeutic effect could be enhanced when combining 125I-UdR therapy with the currently used first-line chemotherapeutic agent temozolomide. 125I-UdR significantly decreased glioblastoma cell viability and migration in vitro and the cell viability was further decreased by co-treatment with methotrexate and/or temozolomide. Intratumoral CED of methotrexate and 125I-UdR with and without concomitant systemic temozolomide chemotherapy significantly reduced the tumor burden in orthotopically xenografted glioblastoma-bearing nude rats. Thus, 100% (8/8) of the animals survived the entire observation period of 180 days when subjected to the combined Auger-chemotherapy while 57% (4/7) survived after the Auger-therapy alone. No animals (0/8) treated with temozolomide alone survived longer than 50 days. Blood samples and post-mortem histology showed no signs of dose-limiting adverse effects. In conclusion, the multidrug approach consisting of CED of methotrexate and 125I-UdR with concomitant systemic temozolomide was safe and very effective leading to 100% survival in an orthotopic xenograft glioblastoma model. Therefore, this therapeutic strategy may be a promising option for future glioblastoma therapy.
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22
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Lee BQ, Nikjoo H, Ekman J, Jönsson P, Stuchbery AE, Kibédi T. A stochastic cascade model for Auger-electron emitting radionuclides. Int J Radiat Biol 2016; 92:641-653. [PMID: 27010453 DOI: 10.3109/09553002.2016.1153810] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
To benchmark a Monte Carlo model of the Auger cascade that has been developed at the Australian National University (ANU) against the literature data. The model is applicable to any Auger-electron emitting radionuclide with nuclear structure data in the format of the Evaluated Nuclear Structure Data File (ENSDF). Schönfeld's algorithms and the BrIcc code were incorporated to obtain initial vacancy distributions due to electron capture (EC) and internal conversion (IC), respectively. Atomic transition probabilities were adopted from the Evaluated Atomic Data Library (EADL) for elements with atomic number, Z = 1-100. Atomic transition energies were evaluated using a relativistic Dirac-Fock method. An energy-restriction protocol was implemented to eliminate energetically forbidden transitions from the simulations. Calculated initial vacancy distributions and average energy spectra of 123I, 124I, and 125I were compared with the literature data. In addition, simulated kinetic energy spectra and frequency distributions of the number of emitted electrons and photons of the three iodine radionuclides are presented. Some examples of radiation spectra of individual decays are also given. Good agreement with the published data was achieved except for the outer-shell Auger and Coster-Kronig transitions. Nevertheless, the model needs to be compared with experimental data in a future study.
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Affiliation(s)
- Boon Q Lee
- a Department of Nuclear Physics , Research School of Physics and Engineering, The Australian National University , Canberra , Australia
| | - Hooshang Nikjoo
- b Department of Oncology-Pathology , Karolinska Institutet , Stockholm , Sweden
| | - Jörgen Ekman
- c Materials Science and Applied Mathematics , Malmö University , Malmö , Sweden
| | - Per Jönsson
- c Materials Science and Applied Mathematics , Malmö University , Malmö , Sweden
| | - Andrew E Stuchbery
- a Department of Nuclear Physics , Research School of Physics and Engineering, The Australian National University , Canberra , Australia
| | - Tibor Kibédi
- a Department of Nuclear Physics , Research School of Physics and Engineering, The Australian National University , Canberra , Australia
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23
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Espenel S, Vallard A, Langrand-Escure J, Ben Mrad M, Méry B, Rivoirard R, Moriceau G, Guy JB, Trone JC, Moncharmont C, Wang G, Diao P, Bernichon É, Chanal É, Fournel P, Magné N. [Carcinomatous meningitis: The radiation therapist's point of view]. Cancer Radiother 2016; 20:54-9. [PMID: 26867467 DOI: 10.1016/j.canrad.2015.09.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Revised: 09/09/2015] [Accepted: 09/11/2015] [Indexed: 11/28/2022]
Abstract
Carcinomatous meningitis complicates 5 to 10% of cancers, essentially with breast cancers, lung cancers and melanomas. The incidence probably increased because of therapeutic advances in oncology. Treatment is based on external beam radiotherapy, systemic treatment, intrathecal chemotherapy and supportive care. The aim of this work was to review data on external radiation therapy and carcinomatous meningitis. There are few evidences on the subject, but it is a major topic of interest. A whole brain radiation therapy is indicated in case of brain metastases or clinical encephalitis. Focal radiation therapy is recommended on symptomatic, bulky or obstructive sites. The dose depends on performance status (20 to 40 Gy in five to 20 fractions), volume to treat and available techniques (classic fractionation or hypofractionation via stereotactic radiosurgery). The objective of radiation therapy is to improve quality of life. Association with systemic therapy improves overall survival. Administration of sequential intrathecal chemotherapy may also improve overall survival, but induces more toxicity. The use of new radiotherapy techniques and development of radiosensitizing molecules in patients with good performance status could improve survival in this frequent complication of cancer.
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Affiliation(s)
- S Espenel
- Département de radiothérapie, institut de cancérologie Lucien-Neuwirth, 108 bis, avenue Albert-Raimond, BP 60008, 42271 Saint-Priest-en-Jarez cedex, France
| | - A Vallard
- Département de radiothérapie, institut de cancérologie Lucien-Neuwirth, 108 bis, avenue Albert-Raimond, BP 60008, 42271 Saint-Priest-en-Jarez cedex, France
| | - J Langrand-Escure
- Département de radiothérapie, institut de cancérologie Lucien-Neuwirth, 108 bis, avenue Albert-Raimond, BP 60008, 42271 Saint-Priest-en-Jarez cedex, France
| | - M Ben Mrad
- Département de radiothérapie, institut de cancérologie Lucien-Neuwirth, 108 bis, avenue Albert-Raimond, BP 60008, 42271 Saint-Priest-en-Jarez cedex, France
| | - B Méry
- Département d'oncologie médicale, institut de cancérologie Lucien-Neuwirth, 108 bis, avenue Albert-Raimond, BP 60008, 42271 Saint-Priest-en-Jarez cedex, France
| | - R Rivoirard
- Département d'oncologie médicale, institut de cancérologie Lucien-Neuwirth, 108 bis, avenue Albert-Raimond, BP 60008, 42271 Saint-Priest-en-Jarez cedex, France
| | - G Moriceau
- Département d'oncologie médicale, institut de cancérologie Lucien-Neuwirth, 108 bis, avenue Albert-Raimond, BP 60008, 42271 Saint-Priest-en-Jarez cedex, France
| | - J-B Guy
- Département de radiothérapie, institut de cancérologie Lucien-Neuwirth, 108 bis, avenue Albert-Raimond, BP 60008, 42271 Saint-Priest-en-Jarez cedex, France
| | - J-C Trone
- Département de radiothérapie, institut de cancérologie Lucien-Neuwirth, 108 bis, avenue Albert-Raimond, BP 60008, 42271 Saint-Priest-en-Jarez cedex, France
| | - C Moncharmont
- Département de radiothérapie, institut de cancérologie Lucien-Neuwirth, 108 bis, avenue Albert-Raimond, BP 60008, 42271 Saint-Priest-en-Jarez cedex, France
| | - G Wang
- Département de radiothérapie, institut de cancérologie Lucien-Neuwirth, 108 bis, avenue Albert-Raimond, BP 60008, 42271 Saint-Priest-en-Jarez cedex, France
| | - P Diao
- Département de radiothérapie, institut de cancérologie Lucien-Neuwirth, 108 bis, avenue Albert-Raimond, BP 60008, 42271 Saint-Priest-en-Jarez cedex, France
| | - É Bernichon
- Département d'oncologie médicale, institut de cancérologie Lucien-Neuwirth, 108 bis, avenue Albert-Raimond, BP 60008, 42271 Saint-Priest-en-Jarez cedex, France
| | - É Chanal
- Département de radiothérapie, institut de cancérologie Lucien-Neuwirth, 108 bis, avenue Albert-Raimond, BP 60008, 42271 Saint-Priest-en-Jarez cedex, France
| | - P Fournel
- Département d'oncologie médicale, institut de cancérologie Lucien-Neuwirth, 108 bis, avenue Albert-Raimond, BP 60008, 42271 Saint-Priest-en-Jarez cedex, France
| | - N Magné
- Département de radiothérapie, institut de cancérologie Lucien-Neuwirth, 108 bis, avenue Albert-Raimond, BP 60008, 42271 Saint-Priest-en-Jarez cedex, France.
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Falzone N, Fernández-Varea JM, Flux G, Vallis KA. Monte Carlo Evaluation of Auger Electron-Emitting Theranostic Radionuclides. J Nucl Med 2015; 56:1441-6. [PMID: 26205298 DOI: 10.2967/jnumed.114.153502] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 07/08/2015] [Indexed: 12/20/2022] Open
Abstract
UNLABELLED Several radionuclides used in medical imaging emit Auger electrons, which, depending on the targeting strategy, either may be exploited for therapeutic purposes or may contribute to an unintentional mean absorbed dose burden. In this study, the virtues of 12 Auger electron-emitting radionuclides were evaluated in terms of cellular S values in concentric and eccentric cell-nucleus arrangements and by comparing their dose-point kernels. METHODS The Monte Carlo code PENELOPE was used to transport the full particulate spectrum of (67)Ga, (80m)Br, (89)Zr, (90)Nb, (99m)Tc, (111)In, (117m)Sn, (119)Sb, (123)I, (125)I, (195m)Pt, and (201)Tl by means of event-by-event simulations. Cellular S values were calculated for varying cell and nucleus radii, and the effects of cell eccentricity on S values were evaluated. Dose-point kernels were determined up to 30 μm. Energy deposition at DNA scales was also compared with an α emitter, (223)Ra. RESULTS PENELOPE-determined S values were generally within 10% of MIRD values when the source and target regions strongly overlapped, that is, S(nucleus←nucleus) configurations, but greater differences were noted for S(nucleus←cytoplasm) and S(nucleus←cell surface) configurations. Cell eccentricity had the greatest effect when the nucleus was small, compared with the cell size, and when the radiation sources were on the cell surface. Dose-point kernels taken together with the energy spectra of the radionuclides can account for some of the differences in energy deposition patterns between the radionuclides. The energy deposition of most Auger electron emitters at DNA scales of 2 nm or less exceeded that of a monoenergetic 5.77-MeV α particle, but not for (223)Ra. CONCLUSION A single-cell dosimetric approach is required to evaluate the efficacy of individual radionuclides for theranostic purposes, taking cell geometry into account, with internalizing and noninternalizing targeting strategies.
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Affiliation(s)
- Nadia Falzone
- Department of Oncology, CR-UK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford, United Kingdom Department of Biomedical Science, Tshwane University of Technology, Pretoria, South Africa
| | | | - Glenn Flux
- Physics Department, Royal Marsden NHSFT, Sutton, Surrey, United Kingdom
| | - Katherine A Vallis
- Department of Oncology, CR-UK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford, United Kingdom
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Rezaee M, Hunting DJ, Sanche L. Correlation between energy deposition and molecular damage from Auger electrons: A case study of ultra-low energy (5-18 eV) electron interactions with DNA. Med Phys 2014; 41:072502. [PMID: 24989405 PMCID: PMC4623756 DOI: 10.1118/1.4881329] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 05/13/2014] [Accepted: 05/18/2014] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The present study introduces a new method to establish a direct correlation between biologically related physical parameters (i.e., stopping and damaging cross sections, respectively) for an Auger-electron emitting radionuclide decaying within a target molecule (e.g., DNA), so as to evaluate the efficacy of the radionuclide at the molecular level. These parameters can be applied to the dosimetry of Auger electrons and the quantification of their biological effects, which are the main criteria to assess the therapeutic efficacy of Auger-electron emitting radionuclides. METHODS Absorbed dose and stopping cross section for the Auger electrons of 5-18 eV emitted by(125)I within DNA were determined by developing a nanodosimetric model. The molecular damages induced by these Auger electrons were investigated by measuring damaging cross section, including that for the formation of DNA single- and double-strand breaks. Nanoscale films of pure plasmid DNA were prepared via the freeze-drying technique and subsequently irradiated with low-energy electrons at various fluences. The damaging cross sections were determined by employing a molecular survival model to the measured exposure-response curves for induction of DNA strand breaks. RESULTS For a single decay of(125)I within DNA, the Auger electrons of 5-18 eV deposit the energies of 12.1 and 9.1 eV within a 4.2-nm(3) volume of a hydrated or dry DNA, which results in the absorbed doses of 270 and 210 kGy, respectively. DNA bases have a major contribution to the deposited energies. Ten-electronvolt and high linear energy transfer 100-eV electrons have a similar cross section for the formation of DNA double-strand break, while 100-eV electrons are twice as efficient as 10 eV in the induction of single-strand break. CONCLUSIONS Ultra-low-energy electrons (<18 eV) substantially contribute to the absorbed dose and to the molecular damage from Auger-electron emitting radionuclides; hence, they should be considered in the dosimetry calculation of such radionuclides. Moreover, absorbed dose is not an appropriate physical parameter for nanodosimetry. Instead, stopping cross section, which describes the probability of energy deposition in a target molecule can be an appropriate nanodosimetric parameter. The stopping cross section is correlated with a damaging cross section (e.g., cross section for the double-strand break formation) to quantify the number of each specific lesion in a target molecule for each nuclear decay of a single Auger-electron emitting radionuclide.
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Affiliation(s)
- Mohammad Rezaee
- Groupe en Sciences des Radiations, Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec J1H 5N4, Canada
| | - Darel J. Hunting
- Groupe en Sciences des Radiations, Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec J1H 5N4, Canada
| | - Léon Sanche
- Groupe en Sciences des Radiations, Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec J1H 5N4, Canada
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Chamberlain MC. Anticancer therapies and CNS relapse: overcoming blood–brain and blood–cerebrospinal fluid barrier impermeability. Expert Rev Neurother 2014; 10:547-61. [DOI: 10.1586/ern.10.14] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Jackson MR, Falzone N, Vallis KA. Advances in anticancer radiopharmaceuticals. Clin Oncol (R Coll Radiol) 2013; 25:604-9. [PMID: 23870756 DOI: 10.1016/j.clon.2013.06.004] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 05/16/2013] [Accepted: 06/12/2013] [Indexed: 12/19/2022]
Abstract
This review highlights recent progress in the development of anticancer radiopharmaceuticals. Molecularly targeted radiotherapy refers to the selective delivery of radionuclides that emit charged particles, such as α particles, β or Auger electrons, to cancer cells via a targeting vector. The discovery of new molecular targets through systems biology and other approaches has widened the scope for radiopharmaceutical development. Innovations in antibody engineering and humanisation, recombinant DNA technology, conjugation chemistry and, increasingly, nanotechnology have provided new approaches to the delivery of radionuclides to cancer cells. The increased availability of radioisotopes that have not traditionally been considered for therapy, such as α particle emitters, has also broadened the indications for targeted radiotherapy.
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Affiliation(s)
- M R Jackson
- CR-UK/MRC Gray Institute for Radiation Oncology and Biology, University of Oxford, Oxford, UK
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Alcolea Palafox M. Molecular structure differences between the antiviral Nucleoside Analogue 5-iodo-2′-deoxyuridine and the natural nucleoside 2′-deoxythymidine using MP2 and DFT methods: conformational analysis, crystal simulations, DNA pairs and possible behaviour. J Biomol Struct Dyn 2013; 32:831-51. [DOI: 10.1080/07391102.2013.789402] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Balagurumoorthy P, Xu X, Wang K, Adelstein SJ, Kassis AI. Effect of distance between decaying (125)I and DNA on Auger-electron induced double-strand break yield. Int J Radiat Biol 2012; 88:998-1008. [PMID: 22732063 DOI: 10.3109/09553002.2012.706360] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE To determine the possible effects of (125)I-to-DNA distance on the magnitude and mechanism of Auger-electron induced-double-strand break (DSB) production. MATERIALS AND METHODS We have synthesized a series of (125)I-labeled Hoechst (H) derivatives ((125)IE-H, (125)IB-H, (125)I-C(8)-H and (125)I-C(12)-H). While all four molecules share a common DNA minor groove binding bis-benzimidazole motif, they are designed to position (125)I at varying distances from the DNA helix. Each Hoechst derivative was incubated at 4°C in phosphate buffered saline (PBS) together with supercoiled (SC) (3)H-pUC19 plasmid DNA (ratio 3:1) ± the •OH scavenger dimethyl sulfoxide (DMSO) (0.2 M). Aliquots were analyzed on agarose gels over time and DSB yields per decay of (125)I atom were determined. Docking of the iodinated compounds on a DNA molecule was carried out to determine the distance between the iodine atom and the central axis of DNA. RESULTS In the absence of DMSO, the results show that the DSB yields decrease monotonically as the (125)I atom is distanced - by 10.5 Å to 13.9 Å - from the DNA helix ((125)IEH: 0.52 ± 0.01; (125)IB-H: 0.24 ± 0.03; (125)I-C(8)-H: 0.18 ± 0.02; (125)I-C(12)-H: 0.10 ± 0.00). In the presence of DMSO, DSB yields for (125)IEH (0.49 ± 0.02) and (125)IB-H (0.26 ± 0.04) remain largely unchanged indicating that DSB are entirely produced by direct effects. Strikingly, (125)I-C(8)-H or (125)I-C(12)-H, did not produce detectable DSB in the presence of DMSO under similar conditions suggesting when (125)I atom is positioned > 12 Å from the DNA, DSB are entirely produced by indirect effects. CONCLUSION These results suggest that at a critical distance between the (125)I atom and the DNA helix, DSB production switches from an 'all' direct to an 'all' indirect mechanism, the latter situation being comparable to the decay of (125)I free in solution. These experimental findings were correlated with theoretical expectations based on microdosimetry.
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Auger Emitting Radiopharmaceuticals for Cancer Therapy. RADIATION DAMAGE IN BIOMOLECULAR SYSTEMS 2012. [DOI: 10.1007/978-94-007-2564-5_28] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Kassis AI. Molecular and cellular radiobiological effects of Auger emitting radionuclides. RADIATION PROTECTION DOSIMETRY 2011; 143:241-7. [PMID: 21106639 PMCID: PMC3108272 DOI: 10.1093/rpd/ncq385] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Although the general radiobiologic principles underlying external beam therapy and radionuclide therapy are similar, significant differences in the biophysical and radiobiologic effects from the two types of radiation continue to accumulate. Here, I will address the unique features that distinguish the molecular and cellular radiobiological effects of Auger electron-emitting radionuclides consequent to (1) the physical characteristics of the decaying atom and its subcellular localisation, (2) DNA topology and (3) the bystander effect. Based on these experimental findings, I postulate that the ability of track structural simulations as primary tools in modelling DNA damage and cellular survival at the molecular level would be greatly enhanced when these contributions are factored in.
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Affiliation(s)
- Amin I Kassis
- Department of Radiology, Harvard Medical School, 200 Longwood Avenue, Armenise Building Room D2-137, Boston, MA 02115, USA.
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Bousis C. Dosimetry on sub-cellular level for intracellular incorporated auger-electron-emitting radionuclides: a comparison of Monte Carlo simulations and analytic calculations. RADIATION PROTECTION DOSIMETRY 2011; 143:33-41. [PMID: 20959340 DOI: 10.1093/rpd/ncq293] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A quantitative dosimetric comparison was performed between Monte Carlo (MC) simulations and analytic calculations at the (sub) cellular level (V79 cells) for four nucleus-incorporated radiochemicals ((125)I/(123)I/(77)Br-UdR and A (125)IP) and two radiochemicals that localised mainly in the cytoplasm of cells ((125)I-dihydrorhodamine and Na(2)(51)CrO(4)). A microscopic investigation around the decay site of the three DNA-incorporated radionuclides ((125)I/(123)I/(77)Br-UdR) was also carried out. On the whole, deviations between MC and analytic calculations for the absorbed dose and dose rate to the cell nucleus were within ∼10%. The dose rate to the nucleus for the radiochemicals that mainly localised in the cytoplasm was greater than that for the nucleus-incorporated ones. Also evident was that the dose rate to the nucleus was approximately the same for the three DNA-incorporated radiochemicals. In contrast to the small differences found between MC and analytic calculations for the (average) absorbed dose to the nucleus, the dosimetric analysis at the microscopic level for the three DNA-incorporated radionuclides showed that the two computational approaches lead to a completely different energy deposition pattern around the decay site.
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Affiliation(s)
- C Bousis
- Department of Medical Physics, University of Ioannina, Ioannina 451 10, Greece.
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Abstract
Neoplastic meningitis (NM) occurs in 5% to 8% of cancer patients, commonly as an end-stage process in previously metastatic disease. As newer therapeutics extend patient survival by maintaining long-term control of systemic malignancies, the incidence of NM is likely to rise. This can be expected both because of a change in the natural history of the underlying disease and the generally poor penetrance of many newer anticancer drugs into the central nervous system, thereby creating a sanctuary site for malignant cells. Currently available treatments have provided limited benefit in overall survival in NM, although long-term survival does occur. Because of the morbidity occasionally associated with treatment, prognostic indicators are being analyzed to identify patients who may benefit from systemic and/or intrathecal therapy before making the decision to initiate treatment. Additionally, because of the relative insensitivity of traditional cerebrospinal fluid analysis, new markers of NM are being investigated. This endeavor is being aided by ongoing research into the underlying biology of the metastatic process.
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