| 1. |
- Altai, Mohamed, et al.
(författare)
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On the prevention of kidney uptake of radiolabeled DARPins
- 2020
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Ingår i: EJNMMI Research. - : SPRINGEROPEN. - 2191-219X. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Background: Designed ankyrin repeat proteins (DARPins) are small engineered scaffold proteins (14-18 kDa) that demonstrated promising tumor-targeting properties in preclinical studies. However, high renal accumulation of activity for DARPins labeled with residualizing labels is a limitation for targeted radionuclide therapy. A better understanding of the mechanisms behind the kidney uptake of DARPins could aid the development of strategies to reduce it. In this study, we have investigated whether the renal uptake of [Tc-99m]Tc(CO)(3)-G3 DARPin could be reduced by administration of compounds that act on various parts of the reabsorption system in the kidney.Results: Co-injection of lysine or Gelofusine was not effective for the reduction of kidney uptake of [Tc-99m]Tc(CO)(3)-G3. Administration of sodium maleate before the injection of [Tc-99m]Tc(CO)(3)-G3 reduced the kidney-associated activity by 60.4 +/- 10.3%, while administration of fructose reduced it by 46.9 +/- 7.6% compared with the control. The decrease in the kidney uptake provided by sodium maleate was also observed for [Tc-99m]Tc(CO)(3)-9_29 DARPin. Preinjection of colchicine, probenecid, mannitol, or furosemide had no effect on the kidney uptake of [Tc-99m]Tc(CO)(3)-G3. Kidney autoradiography showed mainly cortical accumulation of activity for all studied groups.Conclusion: Common clinical strategies were not effective for the reduction of kidney uptake of [Tc-99m]Tc(CO)(3)-G3. Both fructose and maleate lower the cellular ATP level in the proximal tubule cells and their reduction of the kidney reuptake indicates the involvement of an ATP-driven uptake mechanism. The decrease provided by maleate for both G3 and 9_29 DARPins indicates that their uptake proceeds through a mechanism independent of DARPin structure and binding site composition.
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| 2. |
- Bragina, Olga, et al.
(författare)
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Direct Intra-Patient Comparison of Scaffold Protein-Based Tracers, [99mTc]Tc-ADAPT6 and [99mTc]Tc-(HE)3-G3, for Imaging of HER2-Positive Breast Cancer
- 2023
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Ingår i: Cancers. - : MDPI AG. - 2072-6694. ; 15:12
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Tidskriftsartikel (refereegranskat)abstract
- Simple Summary The receptor HER2 is overexpressed in some breast cancers. Tumours with a high HER2 expression can be successfully treated with the antibodies trastuzumab and pertuzumab. The radionuclide imaging of HER2 in disseminated cancer could help to select patients for treatment using these antibodies. Novel radiolabelled small-sized tracers, scaffold proteins, have shown excellent imaging properties in preclinical studies. The scaffold proteins [Tc-99m]Tc-ADAPT6 and DARPin [Tc-99m]Tc-(HE)(3)-G3 have been found to be safe in Phase I clinical trials. They showed promising results in the imaging of HER2. In this study, we compared the distribution of both tracers in the same patients with breast cancer to evaluate whether one of them has any decisive advantage. We found that both tracers provide an excellent visualization of tumours, but the accumulation of [Tc-99m]Tc-ADAPT6 in tumours is higher. The data from this study are essential for researchers developing imaging agents. Previous Phase I clinical evaluations of the radiolabelled scaffold proteins [Tc-99m]Tc-ADAPT6 and DARPin [Tc-99m]Tc-(HE)(3)-G3 in breast cancer patients have demonstrated their safety and indicated their capability to discriminate between HER2-positive and HER2-negative tumours. The objective of this study was to compare the imaging of HER2-positive tumours in the same patients using [Tc-99m]Tc-ADAPT6 and [Tc-99m]Tc-(HE)(3)-G3. Eleven treatment-naive female patients (26-65 years) with HER2-positive primary and metastatic breast cancer were included in the study. Each patient was intravenously injected with [Tc-99m]Tc-ADAPT6, followed by an [Tc-99m]Tc-(HE)(3)-G3 injection 3-4 days later and chest SPECT/CT was performed. All primary tumours were clearly visualized using both tracers. The uptake of [Tc-99m]Tc-ADAPT6 in primary tumours (SUVmax = 4.7 & PLUSMN; 2.1) was significantly higher (p < 0.005) than the uptake of [Tc-99m]Tc-(HE)(3)-G3 (SUVmax = 3.5 & PLUSMN; 1.7). There was no significant difference in primary tumour-to-contralateral site values for [Tc-99m]Tc-ADAPT6 (15.2 & PLUSMN; 7.4) and [Tc-99m]Tc-(HE)(3)-G3 (19.6 & PLUSMN; 12.4). All known lymph node metastases were visualized using both tracers. The uptake of [Tc-99m]Tc-ADAPT6 in all extrahepatic soft tissue lesions was significantly (p < 0.0004) higher than the uptake of [Tc-99m]Tc-(HE)(3)-G3. In conclusion, [Tc-99m]Tc-ADAPT6 and [Tc-99m]Tc-(HE)(3)-G3 are suitable for the visualization of HER2-positive breast cancer. At the selected time points, [Tc-99m]Tc-ADAPT6 has a significantly higher uptake in soft tissue lesions, which might be an advantage for the visualization of small metastases.
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| 3. |
- Bragina, Olga, et al.
(författare)
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Phase I Trial of 99mTc-(HE)3-G3, a DARPin-Based Probe for Imaging of HER2 Expression in Breast Cancer
- 2022
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 63:4, s. 528-535
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Tidskriftsartikel (refereegranskat)abstract
- Radionuclide molecular imaging of human epidermal growth factor receptor type 2 (HER2) expression may enable a noninvasive discrimination between HER2-positive and HER2-negative breast cancers for stratification of patients for HER2-targeted treatments. DARPin (designed ankyrin repeat proteins) G3 is a small (molecular weight, 14 kDa) scaffold protein with picomolar affinity to HER2. The aim of this first-in-humans study was to evaluate the safety, biodistribution, and dosimetry of 99mTc-(HE)3-G3.Methods: Three cohorts of patients with primary breast cancer (each including at least 4 patients with HER2-negative and 5 patients with HER2-positive tumors) were injected with 1,000, 2,000, or 3,000 μg of 99mTc-(HE)3-G3 (287 ± 170 MBq). Whole-body planar imaging followed by SPECT was performed at 2, 4, 6, and 24 h after injection. Vital signs and possible side effects were monitored during imaging and up to 7 d after injection.Results: All injections were well tolerated. No side effects were observed. The results of blood and urine analyses did not differ before and after studies. 99mTc-(HE)3-G3 cleared rapidly from the blood. The highest uptake was detected in the kidneys and liver followed by the lungs, breasts, and small intestinal content. The hepatic uptake after injection of 2,000 or 3,000 μg was significantly (P < 0.05) lower than the uptake after injection of 1,000 μg. Effective doses did not differ significantly between cohorts (average, 0.011 ± 0.004 mSv/MBq). Tumor–to–contralateral site ratios for HER-positive tumors were significantly (P < 0.05) higher than for HER2-negative at 2 and 4 h after injection.Conclusion: Imaging of HER2 expression using 99mTc-(HE)3-G3 is safe and well tolerated and provides a low absorbed dose burden on patients. This imaging enables discernment of HER2-positive and HER2-negative breast cancer. Phase I study data justify further clinical development of 99mTc-(HE)3-G3.
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| 4. |
- Deyev, Sergey M., et al.
(författare)
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Effect of a radiolabel biochemical nature on tumor-targeting properties of EpCAM-binding engineered scaffold protein DARPin Ec1
- 2020
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Ingår i: International Journal of Biological Macromolecules. - : ELSEVIER. - 0141-8130 .- 1879-0003. ; 145, s. 216-225
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Tidskriftsartikel (refereegranskat)abstract
- Radionuclide-based imaging of molecular therapeutic targets might facilitate stratifying patients for specific biotherapeutics. New type of imaging probes, based on designed ankyrin repeat proteins (DARPins), have demonstrated excellent contrast of imaging of human epidermal growth factor type 2 (HER2) expression in preclinical models. We hypothesized that labeling approaches, which result in lipophilic radiometabolites (non-residualizing labels), would provide the best imaging contrast for DARPins that internalize slowly after binding to cancer cells. The hypothesis was tested using DARPin Ec1 that binds to epithelial cell adhesion molecule (EpCAM). EpCAM is a promising therapeutic target. Ec1 was labeled with I-125 using two methods to obtain the non-residualizing labels, while residualizing labels were obtained by labeling it with Tc-99m. All labeled Ec1 variants preserved target specificity and picomolar binding affinity to EpCAM-expressing pancreatic adenocarcinoma BxPC-3 cells. In murine models, all the variants provided similar tumor uptake. However, I-125-PIB-H-6-Ec1 had noticeably lower retention in normal tissues, which provided appreciably higher tumor-to-organ ratios. Furthermore, I-125-PIB-H-6-Ec1 demonstrated the highest imaging contrast in preclinical models than any other EpCAM-imaging agent tested so far. In conclusion, DARPin Ec1 in combination with a non-residualizing label is a promising probe for imaging EpCAM expression a few hours after injection.
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| 5. |
- Deyev, Sergey M., et al.
(författare)
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Influence of the Position and Composition of Radiometals and Radioiodine Labels on Imaging of Epcam Expression in Prostate Cancer Model Using the DARPin Ec1
- 2021
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Ingår i: Cancers. - : MDPI AG. - 2072-6694. ; 13:14
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Tidskriftsartikel (refereegranskat)abstract
- Simple Summary Metastasis-targeting therapy might improve outcomes in oligometastatic prostate cancer. Epithelial cell adhesion molecule (EpCAM) is overexpressed in 40-60% of prostate cancer cases and might be used as a target for specific delivery of toxins and drugs. Radionuclide molecular imaging could enable non-invasive detection of EpCAM and stratification of patients for targeted therapy. Designed ankyrin repeat proteins (DARPins) are scaffold proteins, which can be selected for specific binding to different targets. The DARPin Ec1 binds strongly to EpCAM. To determine an optimal design of Ec1-based probes, we labeled Ec1 at two different positions with four different nuclides (Ga-68, In-111, Co-57 and I-125) and investigated the impact on Ec1 biodistribution. We found that the C-terminus is the best position for labeling and that In-111 and I-125 provide the best imaging contrast. This study might be helpful for scientists developing imaging probes based on scaffold proteins. The epithelial cell adhesion molecule (EpCAM) is intensively overexpressed in 40-60% of prostate cancer (PCa) cases and can be used as a target for the delivery of drugs and toxins. The designed ankyrin repeat protein (DARPin) Ec1 has a high affinity to EpCAM (68 pM) and a small size (18 kDa). Radiolabeled Ec1 might be used as a companion diagnostic for the selection of PCa patients for therapy. The study aimed to investigate the influence of radiolabel position (N- or C-terminal) and composition on the targeting and imaging properties of Ec1. Two variants, having an N- or C-terminal cysteine, were produced, site-specifically conjugated to a DOTA chelator and labeled with cobalt-57, gallium-68 or indium-111. Site-specific radioiodination was performed using ((4-hydroxyphenyl)-ethyl)maleimide (HPEM). Biodistribution of eight radiolabeled Ec1-probes was measured in nude mice bearing PCa DU145 xenografts. In all cases, positioning of a label at the C-terminus provided the best tumor-to-organ ratios. The non-residualizing [I-125]I-HPEM label provided the highest tumor-to-muscle and tumor-to-bone ratios and is more suitable for EpCAM imaging in early-stage PCa. Among the radiometals, indium-111 provided the highest tumor-to-blood, tumor-to-lung and tumor-to-liver ratios and could be used at late-stage PCa. In conclusion, label position and composition are important for the DARPin Ec1.
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| 6. |
- Deyev, Sergey M., et al.
(författare)
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Preclinical Evaluation of HER2-Targeting DARPin G3: Impact of Albumin-Binding Domain (ABD) Fusion
- 2024
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Ingår i: International Journal of Molecular Sciences. - : Multidisciplinary Digital Publishing Institute (MDPI). - 1661-6596 .- 1422-0067. ; 25:8
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Tidskriftsartikel (refereegranskat)abstract
- Designed ankyrin repeat protein (DARPin) G3 is an engineered scaffold protein. This small (14.5 kDa) targeting protein binds with high affinity to human epidermal growth factor receptor 2 (HER2). HER2 is overexpressed in several cancers. The use of the DARPin G3 for radionuclide therapy is complicated by its high renal reabsorption after clearance via the glomeruli. We tested the hypothesis that a fusion of the DARPin G3 with an albumin-binding domain (ABD) would prevent rapid renal excretion and high renal reabsorption resulting in better tumour targeting. Two fusion proteins were produced, one with the ABD at the C-terminus (G3-ABD) and another at the N-terminus (ABD-G3). Both variants were labelled with 177Lu. The binding properties of the novel constructs were evaluated in vitro and their biodistribution was compared in mice with implanted human HER2-expressing tumours. Fusion with the ABD increased the retention time of both constructs in blood compared with the non-ABD-fused control. The effect of fusion with the ABD depended strongly on the order of the domains in the constructs, resulting in appreciably better targeting properties of [177Lu]Lu-G3-ABD. Our data suggest that the order of domains is critical for the design of targeting constructs based on scaffold proteins.
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| 7. |
- Larkina, Maria, et al.
(författare)
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Comparative Preclinical Evaluation of HYNIC-Modified Designed Ankyrin Repeat Proteins G3 for the 99mTc-Based Imaging of HER2-Expressing Malignant Tumors
- 2024
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Ingår i: Molecular Pharmaceutics. - : American Chemical Society (ACS). - 1543-8384 .- 1543-8392. ; 21:4, s. 1919-1932
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Tidskriftsartikel (refereegranskat)abstract
- HER2 status determination is a necessary step for the proper choice of therapy and selection of patients for the targeted treatment of cancer. Targeted radiotracers such as radiolabeled DARPins provide a noninvasive and effective way for the molecular imaging of HER2 expression. This study aimed to evaluate tumor-targeting properties of three 99mTc-labeled DARPin G3 variants containing Gly-Gly-Gly-Cys (G3C), (Gly-Gly-Gly-Ser)3-Cys ((G3S)3C), or Glu-Glu-Glu-Cys (E3C) amino acid linkers at the C-terminus and conjugated to the HYNIC chelating agent, as well as to compare them with the clinically evaluated DARPin G3 labeled with 99mTc(CO)3 using the (HE)3-tag at the N-terminus. The labeling of DARPin G3-HYNIC variants provided radiochemical yields in the range of 50–80%. Labeled variants bound specifically to human HER2-expressing cancer cell lines with affinities in the range of 0.5–3 nM. There was no substantial influence of the linker and HYNIC chelator on the binding of 99mTc-labeled DARPin G3 variants to HER2 in vitro; however, [99mTc]Tc-G3-(G3S)3C-HYNIC had the highest affinity. Comparative biodistribution of [99mTc]Tc-G3-G3C-HYNIC, [99mTc]Tc-G3-(G3S)3C-HYNIC, [99mTc]Tc-G3-E3C-HYNIC, and [99mTc]Tc-(HE)3-G3 in healthy CD1 mice showed that there was a strong influence of the linkers on uptake in normal tissues. [99mTc]Tc-G3-E3C-HYNIC had an increased retention of activity in the liver and the majority of other organs compared to the other conjugates. The tumor uptake of [99mTc]Tc-G3-(G3S)3C-HYNIC and [99mTc]Tc-(HE)3-G3 in Nu/j mice bearing SKOV-3 xenografts was similar. The specificity of tumor targeting in vivo was demonstrated for both tracers. [99mTc]Tc-G3-(G3S)3C-HYNIC provided comparable, although slightly lower tumor-to-lung, tumor-to spleen and tumor-to-liver ratios than [99mTc]Tc-(HE)3-G3. Radiolabeling of DARPin G3-HYNIC conjugates with 99mTc provided the advantage of a single-step radiolabeling procedure; however, the studied HYNIC conjugates did not improve imaging contrast compared to the 99mTc-tricarbonyl-labeled DARPin G3. At this stage, [99mTc]Tc-(HE)3-G3 remains the most promising candidate for the clinical imaging of HER2-overexpressing cancers.
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| 8. |
- Larkina, Mariia, et al.
(författare)
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Comparative Preclinical Evaluation of Peptide-Based Chelators for the Labeling of DARPin G3 with 99mTc for Radionuclide Imaging of HER2 Expression in Cancer
- 2022
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 23:21, s. 13443-
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Tidskriftsartikel (refereegranskat)abstract
- Non-invasive radionuclide imaging of human epidermal growth factor receptor type 2 (HER2) expression in breast, gastroesophageal, and ovarian cancers may stratify patients for treatment using HER2-targeted therapeutics. Designed ankyrin repeat proteins (DARPins) are a promising type of targeting probe for radionuclide imaging. In clinical studies, the DARPin [Tc-99m]Tc-(HE)(3)-G3 labeled using a peptide-based chelator His-Glu-His-Glu-His-Glu ((HE)(3)), provided clear imaging of HER2 expressing breast cancer 2-4 h after injection. The goal of this study was to evaluate if the use of cysteine-containing peptide-based chelators Glu-Glu-Glu-Cys (E3C), Gly-Gly-Gly-Cys (G(3)C), and Gly-Gly-Gly-Ser-Cys connected via a (Gly-Gly-Gly-Ser)(3)-linker (designated as G3-(G(3)S)(3)C) would further improve the contrast of imaging using Tc-99m-labeled derivatives of G3. The labeling of the new variants of G3 provided a radiochemical yield of over 95%. Labeled G3 variants bound specifically to human HER2-expressing cancer cell lines with affinities in the range of 1.9-5 nM. Biodistribution of [Tc-99m]Tc-G3-G(3)C, [Tc-99m]Tc-G3-(G(3)S)(3)C, and [Tc-99m]Tc-G3-E3C in mice was compared with the biodistribution of [Tc-99m]Tc-(HE)(3)-G3. It was found that the novel variants provide specific accumulation in HER2-expressing human xenografts and enable discrimination between tumors with high and low HER2 expression. However, [Tc-99m]Tc-(HE)(3)-G3 provided better contrast between tumors and the most frequent metastatic sites of HER2-expressing cancers and is therefore more suitable for clinical applications.
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| 9. |
- Tolmachev, Vladimir, et al.
(författare)
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Direct In Vivo Comparison of Tc-99m-Labeled Scaffold Proteins, DARPin G3 and ADAPT6, for Visualization of HER2 Expression and Monitoring of Early Response for Trastuzumab Therapy
- 2022
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 23:23
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Tidskriftsartikel (refereegranskat)abstract
- Non-invasive radionuclide molecular visualization of human epidermal growth factor receptor type 2 (HER2) can provide stratification of patients for HER2-targeting therapy. This method can also enable monitoring of the response to such therapies, thereby making treatment personalized and more efficient. Clinical evaluation in a phase I study demonstrated that injections of two scaffold protein-based imaging probes, [Tc-99m]Tc-(HE)(3)-G3 and [Tc-99m]Tc-ADAPT6, are safe, well-tolerated and cause a low level of radioactivity in healthy tissue. The goal of this preclinical study was to select the best probe for stratification of patients and response monitoring. Biodistribution of both tracers was compared in mice bearing SKOV-3 xenografts with high HER2 expression or MDA-MB-468 xenografts with very low expression. Changes in accumulation of the probes in SKOV-3 tumors 24 h after injection of trastuzumab were evaluated. Both [Tc-99m]Tc-ADAPT6 and [Tc-99m]Tc-(HE)(3)-G3 permitted high contrast imaging of HER2-expressing tumors and a clear discrimination between tumors with high and low HER2 expression. However, [Tc-99m]Tc-ADAPT6 has better preconditions for higher sensitivity and specificity of stratification. On the other hand, [Tc-99m]Tc-(HE)(3)-G3 is capable of detecting the decrease of HER2 expression on response to trastuzumab therapy only 24 h after injection of the loading dose. This indicates that the [Tc-99m]Tc-(HE)(3)-G3 tracer would be better for monitoring early response to such treatment. The results of this study should be considered in planning of further clinical development of HER2 imaging probes.
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| 10. |
- Tolmachev, Vladimir, et al.
(författare)
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Targeted nuclear medicine. Seek and destroy
- 2022
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Ingår i: Russian Chemical Reviews. - : IOP Publishing. - 0036-021X .- 1468-4837. ; 91:3
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Forskningsöversikt (refereegranskat)abstract
- The targeted delivery of radionuclides to tumours holds great promise for diagnosis and treatment of malignant neoplasms. The development of scaffold proteins has significantly simplified the design of targeting agents with desirable properties. This review comprehensively describes the key aspects of the design of radionuclide compounds, including classification of radionuclides, methodology for their attachment to targeting agents and characteristics of these agents that affect their behaviour in the body. Various targeting molecules are compared in terms of their ability to specifically find malignant foci in the body. The most recent achievements of cancer theranostics that aim at increasing the selectivity of antitumour effect are described, such as the fusion of targeting scaffold proteins with the albumin-binding domain and pretargeting. Special attention is paid to the creation of targeted radionanomaterials. Advantages and disadvantages of different strategies are analyzed and approaches for improving the delivery to tumours and for minimizing the undesirable impact on healthy organs and tissues are proposed. Particular emphasis is placed on the results of studies published in 2020 ?? 2021 that have not yet been covered by reviews.
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