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Rich T, Pan D, Chordia M, Keppel C, Beylin D, Stepanov P, Jung M, Pang D, Grindrod S, Dritschilo A. 18Oxygen Substituted Nucleosides Combined with Proton Beam Therapy: Therapeutic Transmutation In Vitro. Int J Part Ther 2021; 7:11-18. [PMID: 33829069 PMCID: PMC8019575 DOI: 10.14338/ijpt-d-20-00036.1] [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: 07/18/2020] [Accepted: 12/17/2020] [Indexed: 11/21/2022] Open
Abstract
Purpose Proton therapy precisely delivers radiation to cancers to cause damaging strand breaks to cellular DNA, kill malignant cells, and stop tumor growth. Therapeutic protons also generate short-lived activated nuclei of carbon, oxygen, and nitrogen atoms in patients as a result of atomic transmutations that are imaged by positron emission tomography (PET). We hypothesized that the transition of 18O to 18F in an 18O-substituted nucleoside irradiated with therapeutic protons may result in the potential for combined diagnosis and treatment for cancer with proton therapy. Materials and Methods Reported here is a feasibility study with a therapeutic proton beam used to irradiate H218O to a dose of 10 Gy produced by an 85 MeV pristine Bragg peak. PET imaging initiated >45 minutes later showed an 18F decay signal with T1/2 of ∼111 minutes. Results The 18O to 18F transmutation effect on cell survival was tested by exposing SQ20B squamous carcinoma cells to physiologic 18O-thymidine concentrations of 5 μM for 48 hours followed by 1- to 9-Gy graded doses of proton radiation given 24 hours later. Survival analyses show radiation sensitization with a dose modification factor (DMF) of 1.2. Conclusions These data support the idea of therapeutic transmutation in vitro as a biochemical consequence of proton activation of 18O to 18F in substituted thymidine enabling proton radiation enhancement in a cancer cell. 18O-substituted molecules that incorporate into cancer targets may hold promise for improving the therapeutic window of protons and can be evaluated further for postproton therapy PET imaging.
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Affiliation(s)
- Tyvin Rich
- The University of Virginia, Radiation Oncology and Diagnostic Radiology, Charlottesville, VA, USA.,Georgetown University, Radiation Medicine, Washington, DC, USA.,Shuttle Pharmaceuticals, Inc, Rockville, MD, USA.,Hampton University Proton Therapy Institute, Hampton, VA, USA
| | - Dongfeng Pan
- The University of Virginia, Radiology and Medical Imaging, Charlottesville, VA, USA
| | - Mahendra Chordia
- The University of Virginia, Radiology and Medical Imaging, Charlottesville, VA, USA
| | - Cynthia Keppel
- Hampton University Proton Therapy Institute, Hampton, VA, USA.,Thomas Jefferson National Accelerator Facility, Newport News, VA, USA
| | | | | | - Mira Jung
- Georgetown University, Radiation Medicine, Washington, DC, USA
| | - Dalong Pang
- Georgetown University, Radiation Medicine, Washington, DC, USA
| | | | - Anatoly Dritschilo
- Georgetown University, Radiation Medicine, Washington, DC, USA.,Shuttle Pharmaceuticals, Inc, Rockville, MD, USA
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Windhorst AD, Klein PJ, Eisenbarth J, Oeser T, Kruijer PS, Eisenhut M. 3′-Sulfonylesters of 2,5′-anhydro-1-(2-deoxy-β-d-threo-pentofuranosyl)thymine as precursors for the synthesis of [18F]FLT: syntheses and radiofluorination trials. Nucl Med Biol 2008; 35:413-23. [DOI: 10.1016/j.nucmedbio.2008.02.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Revised: 02/18/2008] [Accepted: 02/18/2008] [Indexed: 11/25/2022]
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