Dosimetric impact of Ac-227 in accelerator-produced Ac-225 for alpha-emitter radiopharmaceutical therapy of patients with hematological malignancies: a pharmacokinetic modeling analysis
Abstract Background Actinium-225 is an alpha-particle emitter under investigation for use in radiopharmaceutical therapy. To address limited supply, accelerator-produced 225Ac has been recently made available. Accelerator-produced 225Ac via 232Th irradiation (denoted 225/7Ac) contains a low percenta...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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SpringerOpen
2021-08-01
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| Series: | EJNMMI Physics |
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| Online Access: | https://doi.org/10.1186/s40658-021-00410-6 |
| _version_ | 1819124941400834048 |
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| author | George Sgouros Bin He Nitya Ray Dale L. Ludwig Eric C. Frey |
| author_facet | George Sgouros Bin He Nitya Ray Dale L. Ludwig Eric C. Frey |
| author_sort | George Sgouros |
| collection | DOAJ |
| description | Abstract Background Actinium-225 is an alpha-particle emitter under investigation for use in radiopharmaceutical therapy. To address limited supply, accelerator-produced 225Ac has been recently made available. Accelerator-produced 225Ac via 232Th irradiation (denoted 225/7Ac) contains a low percentage (0.1–0.3%) of 227Ac (21.77-year half-life) activity at end of bombardment. Using pharmacokinetic modeling, we have examined the dosimetric impact of 227Ac on the use of accelerator-produced 225Ac for radiopharmaceutical therapy. We examine the contribution of 227Ac and its daughters to tissue absorbed doses. The dosimetric analysis was performed for antibody-conjugated 225/7Ac administered intravenously to treat patients with hematological cancers. Published pharmacokinetic models are used to obtain the distribution of 225/7Ac-labeled antibody and also the distribution of either free or antibody-conjugated 227Th. Results Based on our modeling, the tissue specific absorbed dose from 227Ac would be negligible in the context of therapy, less than 0.02 mGy/MBq for the top 6 highest absorbed tissues and less than 0.007 mGy/MBq for all other tissues. Compared to that from 225Ac, the absorbed dose from 227Ac makes up a very small component (less than 0.04%) of the total absorbed dose delivered to the 6 highest dose tissues: red marrow, spleen, endosteal cells, liver, lungs and kidneys when accelerator produced 225/7Ac-conjugated anti-CD33 antibody is used to treat leukemia patients. For all tissues, the dominant contributor to the absorbed dose arising from the 227Ac is 227Th, the first daughter of 227Ac which has the potential to deliver absorbed dose both while it is antibody-bound and while it is free. CONCLUSIONS: These results suggest that the absorbed dose arising from 227Ac to normal organs would be negligible for an 225/7Ac-labeled antibody that targets hematological cancer. |
| first_indexed | 2024-12-22T07:32:14Z |
| format | Article |
| id | doaj.art-4be748613bc9471289128dc28816d5e9 |
| institution | Directory Open Access Journal |
| issn | 2197-7364 |
| language | English |
| last_indexed | 2024-12-22T07:32:14Z |
| publishDate | 2021-08-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | EJNMMI Physics |
| spelling | doaj.art-4be748613bc9471289128dc28816d5e92022-12-21T18:33:59ZengSpringerOpenEJNMMI Physics2197-73642021-08-018111610.1186/s40658-021-00410-6Dosimetric impact of Ac-227 in accelerator-produced Ac-225 for alpha-emitter radiopharmaceutical therapy of patients with hematological malignancies: a pharmacokinetic modeling analysisGeorge Sgouros0Bin He1Nitya Ray2Dale L. Ludwig3Eric C. Frey4Russell H. Morgan Department of Radiology and Radiological Science, School of Medicine, Johns Hopkins UniversityRadiopharmaceutical Imaging and Dosimetry, LLC (Rapid)Actinium Pharmaceuticals, Inc.Actinium Pharmaceuticals, Inc.Radiopharmaceutical Imaging and Dosimetry, LLC (Rapid)Abstract Background Actinium-225 is an alpha-particle emitter under investigation for use in radiopharmaceutical therapy. To address limited supply, accelerator-produced 225Ac has been recently made available. Accelerator-produced 225Ac via 232Th irradiation (denoted 225/7Ac) contains a low percentage (0.1–0.3%) of 227Ac (21.77-year half-life) activity at end of bombardment. Using pharmacokinetic modeling, we have examined the dosimetric impact of 227Ac on the use of accelerator-produced 225Ac for radiopharmaceutical therapy. We examine the contribution of 227Ac and its daughters to tissue absorbed doses. The dosimetric analysis was performed for antibody-conjugated 225/7Ac administered intravenously to treat patients with hematological cancers. Published pharmacokinetic models are used to obtain the distribution of 225/7Ac-labeled antibody and also the distribution of either free or antibody-conjugated 227Th. Results Based on our modeling, the tissue specific absorbed dose from 227Ac would be negligible in the context of therapy, less than 0.02 mGy/MBq for the top 6 highest absorbed tissues and less than 0.007 mGy/MBq for all other tissues. Compared to that from 225Ac, the absorbed dose from 227Ac makes up a very small component (less than 0.04%) of the total absorbed dose delivered to the 6 highest dose tissues: red marrow, spleen, endosteal cells, liver, lungs and kidneys when accelerator produced 225/7Ac-conjugated anti-CD33 antibody is used to treat leukemia patients. For all tissues, the dominant contributor to the absorbed dose arising from the 227Ac is 227Th, the first daughter of 227Ac which has the potential to deliver absorbed dose both while it is antibody-bound and while it is free. CONCLUSIONS: These results suggest that the absorbed dose arising from 227Ac to normal organs would be negligible for an 225/7Ac-labeled antibody that targets hematological cancer.https://doi.org/10.1186/s40658-021-00410-6Actinium-225Alpha-emitterRadiopharmaceutical therapyDosimetryCompartmental modeling |
| spellingShingle | George Sgouros Bin He Nitya Ray Dale L. Ludwig Eric C. Frey Dosimetric impact of Ac-227 in accelerator-produced Ac-225 for alpha-emitter radiopharmaceutical therapy of patients with hematological malignancies: a pharmacokinetic modeling analysis EJNMMI Physics Actinium-225 Alpha-emitter Radiopharmaceutical therapy Dosimetry Compartmental modeling |
| title | Dosimetric impact of Ac-227 in accelerator-produced Ac-225 for alpha-emitter radiopharmaceutical therapy of patients with hematological malignancies: a pharmacokinetic modeling analysis |
| title_full | Dosimetric impact of Ac-227 in accelerator-produced Ac-225 for alpha-emitter radiopharmaceutical therapy of patients with hematological malignancies: a pharmacokinetic modeling analysis |
| title_fullStr | Dosimetric impact of Ac-227 in accelerator-produced Ac-225 for alpha-emitter radiopharmaceutical therapy of patients with hematological malignancies: a pharmacokinetic modeling analysis |
| title_full_unstemmed | Dosimetric impact of Ac-227 in accelerator-produced Ac-225 for alpha-emitter radiopharmaceutical therapy of patients with hematological malignancies: a pharmacokinetic modeling analysis |
| title_short | Dosimetric impact of Ac-227 in accelerator-produced Ac-225 for alpha-emitter radiopharmaceutical therapy of patients with hematological malignancies: a pharmacokinetic modeling analysis |
| title_sort | dosimetric impact of ac 227 in accelerator produced ac 225 for alpha emitter radiopharmaceutical therapy of patients with hematological malignancies a pharmacokinetic modeling analysis |
| topic | Actinium-225 Alpha-emitter Radiopharmaceutical therapy Dosimetry Compartmental modeling |
| url | https://doi.org/10.1186/s40658-021-00410-6 |
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