Medical Radiology and Radiation Safety. 2026. Vol. 71. № 1
DOI:10.33266/1024-6177-2026-71-1-67-72
V.K. Tishchenko1, A.V. Fedorova1, O.F. Chibisova1, N.B. Morozova2,
A.A. Lebedeva1, S.P. Orlenko1, A.A. Solyanov1, A.A. Ostroukhov1,
O.P. Vlasova1, 3, A.D. Kaprin2, 3, 4
Biological Distribution of Radioconjugates Based
on Somatostatin Analogs and Radionuclide Actinium-225
1 A.F. Tsyb Medical Radiological Research Centre, Obninsk, Russia
2 P.A. Hertsen Moscow Oncology Research Institute, Moscow, Russia
3 National Medical Research Radiological Centre, Obninsk, Russia
4 Рeoples Friendship University of Russia, Moscow, Russia
Contact person: Viktoriia Konstantinovna Tishchenko, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
ABSTRACT
Purpose: Comparative studies of metal complexes 225Ac-DOTA-TOC and 225Ac-DOTA-TATE biodistribution in laboratory animals with an experimental model of malignant tumor and optimal radioconjugate determination for further preclinical studies.
Material and methods: Radiochemical synthesis of 225Ac-DOTA-TOC and 225Ac-DOTA-TATE metal complexes was carried out using chemical precursors DOTA-TOC and DOTA-TATE in lyophilic form (JSC Pharm-Sintez) and actinium-225 chloride (IPPE JSC). Biodistribution studies were performed in immunodeficient NU/J mice, females, with subcutaneously transplanted SK-Mel-28 melanoma. Biodistribution of radiopharmaceuticals was assessed ex vivo and measured by the radiometric method with an automatic gamma counter by the specific activity in samples of organs and tissues measurement.
Results: Radioconjugates 225Ac-DOTA-TOC and 225Ac-DOTA-TATE had similar biodistribution in tumor-bearing animals after a single intravenous administration. The highest accumulation of both radioconjugates was observed in the kidneys: 8.908–45.243 %ID/g and 3.816–25.694 %ID/g for 225Ac-DOTA-TOC and 225Ac-DOTA-TATE, respectively. The uptake of 225Ac-DOTA-TATE (0.179–3.869 %ID/g) in tumor was higher than 225Ac-DOTA-TOC (0.120–1.514 %ID/g), however, statistically significant differences (p < 0.05) were observed only at 5 min after administration. There were not statistically significant differences between the uptake of 225Ac-DOTA-TOC and 225Ac-DOTA-TATE in other organs and tissues. Analysis of tumor/organs values showed that the concentration of 225Ac-DOTA-TOC and 225Ac-DOTA-TATE in tumor was higher than in most organs, except liver and kidneys. The lowest uptake of both radiopharmaceuticals was registered in the brain (less than 0.1 %ID/g).
Conclusion: According to the results of this study, the radioconjugate 225Ac-DOTA-TATE has optimal biodistribution (higher accumulation in the tumor and lower in the kidneys as compared with 225Ac-DOTA-TOC), so 225Ac-DOTA-TATE was chosen for further preclinical studies.
Keywords: radiopharmaceuticals, actinium-225, somatostatin analogs, DOTA-TOC, DOTA-TATE, biodistribution, mice
For citation: Tishchenko VK, Fedorova AV, Chibisova OF, Morozova NB, Lebedeva AA, Orlenko SP, Solyanov AA, Ostroukhov AA, Vlasova OP, Kaprin AD. Biological Distribution of Radioconjugates Based on Somatostatin Analogs and Radionuclide Actinium-225. Medical Radiology and Radiation Safety. 2026;71(1):67–72. (In Russian). DOI:10.33266/1024-6177-2026-71-1-67-72
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PDF (RUS) Full-text article (in Russian)
Conflict of interest. The authors declare no conflict of interest.
Financing. The research was carried out with the financial support of Ministry of Health of the Russian Federation within implementation of state assignment № 124030500022-1.
Contribution. A.D. Kaprin aided in the concept and plan of the study; V.K. Tishchenko, O.P. Vlasova provided collection and analysis of data; preparation of the manuscript – V.K. Tishchenko, O.P. Vlasova.
Article received: 20.11.2025. Accepted for publication: 25.12.2025.