| 1. |
- Altai, Mohamed, et al.
(författare)
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Feasibility of Affibody-Based Bioorthogonal Chemistry Mediated Radionuclide Pretargeting
- 2016
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Ingår i: Journal of Nuclear Medicine. - : SOC NUCLEAR MEDICINE. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 57:3, s. 431-436
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Tidskriftsartikel (refereegranskat)abstract
- Affibody molecules constitute a new class of probes for radionuclide tumor targeting. The small size of Affibody molecules is favorable for rapid localization in tumors and clearance from circulation. However, high renal reabsorption of Affibody molecules prevents the use of residualizing radiometals, including several promising low-energy (beta- and alpha-emitters, for radionuclide therapy. We tested a hypothesis that Affibody-based pretargeting mediated by a bioorthogonal interaction between trans-cyclooctene (TCO) and tetrazine would provide higher accumulation of radiometals in tumor xenografts than in the kidneys. Methods: TCO was conjugated to the anti-human epidermal growth factor receptor 2 (HER2) Affibody molecule Z(2395). DOTA-tetrazine was labeled with In-111 and Lu-177. In vitro pretargeting was studied in HER2-expressing SKOV-3 and BT474 cell lines. In vivo studies were performed on BALB/C nu/nu mice bearing SKOV-3 xenografts. Results: I-125-Z(2395)-TCO bound specifically to HER2-expressing cells in vitro with an affinity of 45 +/- 16 pM. In-111-tetrazine bound specifically and selectively to Z(2325)-TCO pretreated cells. In vivo studies demonstrated HER2-specific I-125-Z(2395)-TCO accumulation in xenografts. TCO-mediated In-111-tetrazine localization was shown in tumors, when the radiolabeled tracer was injected 4 h after an injection of Z(2395)-TCO. At 1 h after injection, the tumor uptake of In-111-tetrazine and Lu-177-tetrazine was approximately 2-fold higher than the renal uptake. Pretargeting provided more than a 56-fold reduction of renal uptake of In-111 in comparison with direct targeting. Conclusion: The feasibility of Affibody-based bioorthogonal chemistry-mediated pretargeting was demonstrated. The use of pre-targeting provides a substantial reduction of radiometal accumulation in kidneys, creating preconditions for palliative radionuclide therapy.
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| 2. |
- Tano, Hanna, et al.
(författare)
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Comparative Evaluation of Novel Lu-177-Labeled PNA Probes for Affibody-Mediated PNA-Based Pretargeting
- 2021
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Ingår i: Cancers. - : MDPI AG. - 2072-6694. ; 13:3
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Tidskriftsartikel (refereegranskat)abstract
- Simple Summary Affibody molecules are small, engineered affinity proteins based on a nonimmunoglobulin scaffold. Affibody-based radionuclide imaging probes have demonstrated excellent tumor targeting. However, the renal clearance of affibody molecules is accompanied by high reabsorption and retention of activity in the kidney, which prevents their use for radionuclide therapy. We have previously shown the feasibility of overcoming the high renal uptake using a pretargeting approach for affibody-mediated therapy based on peptide nucleic acid (PNA) hybridization. In this study, we test the hypothesis that shortening the PNA pretargeting probes would further increase the difference between the accumulation of radiometals in tumor xenografts and in kidneys. A series of novel PNA probes has been designed and evaluated in vitro and in vivo. We have found that a variant containing 9 nucleobases enables a two-fold increase of the tumor-to-kidney dose ratio compared with a variant containing 15 nucleobases. This creates preconditions for more efficient therapy of cancer. Affibody-mediated PNA-based pretargeting is a promising approach to radionuclide therapy of HER2-expressing tumors. In this study, we test the hypothesis that shortening the PNA pretargeting probes would increase the tumor-to-kidney dose ratio. The primary probe Z(HER2:342)-SR-HP15 and the complementary secondary probes HP16, HP17, and HP18, containing 9, 12, and 15 nucleobases, respectively, and carrying a 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) chelator were designed, synthesized, characterized in vitro, and labeled with Lu-177. In vitro pretargeting was studied in HER2-expressing SKOV3 and BT474 cell lines. The biodistribution of these novel probes was evaluated in immunodeficient mice bearing SKOV3 xenografts and compared to the previously studied [Lu-177]Lu-HP2. Characterization confirmed the formation of high-affinity duplexes between HP15 and the secondary probes, with the affinity correlating with the length of the complementary PNA sequences. All the PNA-based probes were bound specifically to HER2-expressing cells in vitro. In vivo studies demonstrated HER2-specific uptake of all Lu-177-labeled probes in xenografts in a pretargeting setting. The ratio of cumulated radioactivity in the tumor to the radioactivity in kidneys was dependent on the secondary probe's size and decreased with an increased number of nucleobases. The shortest PNA probe, [Lu-177]Lu-HP16, showed the highest tumor-to-kidney ratio. [Lu-177]Lu-HP16 is the most promising secondary probe for affibody-mediated tumor pretargeting.
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| 3. |
- Westerlund, Kristina, et al.
(författare)
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Radionuclide Therapy of HER2-Expressing Human Xenografts Using Affibody-Based Peptide Nucleic Acid-Mediated Pretargeting : In Vivo Proof of Principle
- 2018
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 59:7, s. 1092-1098
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Tidskriftsartikel (refereegranskat)abstract
- Affibody molecules are small proteins engineered using a nonanti-body scaffold. Radiolabeled Affibody molecules are excellent imaging probes, but their application to radionuclide therapy has been prevented by high renal reabsorption. The aim of this study was to test the hypothesis that Affibody-based peptide nucleic acid (PNA)-mediated pretargeted therapy of human epidermal growth factor receptor 2 (HER2)-expressing cancer extends survival without accompanying renal toxicity.Methods: A HER2-targeting Affibody molecule ligated with an AGTCGTGATGTAGTC PNA hybridization probe (Z(HER2:342)-SR-HP1) was used as the primary pretargeting agent. A complementary AGTCGTGATGTAGTC PNA conjugated to the chelator DOTA and labeled with the radionuclide Lu-177 (Lu-177-HP2) was used as the secondary agent. The influence of different factors on pretargeting was investigated. Experimental radionuclide therapy in mice bearing SKOV-3 xenografts was performed in 6 cycles separated by 7 d.Results: Optimal tumor targeting was achieved when 16 MBq/3.5 mu g (0.65 nmol) of Lu-177-HP2 was injected 16 h after injection of 100 mu g (7.7 nmol) of Z(HER2:342)-SR-HP1. The calculated absorbed dose to tumors was 1,075 mGy/MBq, whereas the absorbed dose to kidneys was 206 mGy/MBq and the absorbed dose to blood (surrogate of bone marrow) was 4 mGy/MBq. Survival of mice was significantly longer (P < 0.05) in the treatment group (66 d) than in the control groups treated with the same amount of Z(HER2:342)-SR-HP1 only (37 d), the same amount and activity of Lu-177-HP2 only (32 d), or phosphate-buffered saline (37 d).Conclusion: The studied pretargeting system can deliver an absorbed dose to tumors appreciably exceeding absorbed doses to critical organs, making Affibody-based PNA-mediated pretargeted radionuclide therapy highly attractive.
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| 4. |
- Abouzayed, Ayman, et al.
(författare)
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177Lu-labeled PSMA targeting therapeutic with optimized linker for treatment of disseminated prostate cancer; evaluation of biodistribution and dosimetry
- 2023
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Ingår i: Frontiers in Oncology. - : Frontiers Media S.A.. - 2234-943X. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Prostate specific membrane antigen (PSMA), highly expressed in metastatic castration-resistant prostate cancer (mCRPC), is an established therapeutic target. Theranostic PSMA-targeting agents are widely used in patient management and has shown improved outcomes for mCRPC patients. Earlier, we optimized a urea-based probe for radionuclide visualization of PSMA-expression in vivo using computer modeling. With the purpose to develop a targeting agent equally suitable for radionuclide imaging and therapy, the agent containing DOTA chelator was designed (BQ7876). The aim of the study was to test the hypothesis that Lu-177-labeled BQ7876 possesses target binding and biodistribution properties potentially enabling its use for radiotherapy.Methods: BQ7876 was synthesized and labeled with Lu-177. Specificity and affinity of [Lu-177]Lu-BQ7876 to PSMA-expressing PC3-pip cells was evaluated and its processing after binding to cells was studied. Animal studies in mice were performed to assess its biodistribution in vivo, target specificity and dosimetry. [Lu-177]Lu-PSMA-617 was simultaneously evaluated for comparison.Results: BQ7876 was labeled with Lu-177 with radiochemical yield >99%. Its binding to PSMA was specific in vitro and in vivo when tested in antigen saturation conditions as well as in PSMA-negative PC-3 tumors. The binding of [Lu-177]Lu-BQ7876 to living cells was characterized by rapid association, while the dissociation included a rapid and a slow phase with affinities K-D1 = 3.8 nM and K-D2 = 25 nM. The half-maximal inhibitory concentration for Lu-nat-BQ7876 was 59 nM that is equal to 61 nM for Lu-nat-PSMA-617. Cellular processing of [Lu-177]Lu-BQ7876 was accompanied by slow internalization. [Lu-177]Lu-BQ7876 was cleared from blood and normal tissues rapidly. Initial elevated uptake in kidneys decreased rapidly, and by 3 h post injection, the renal uptake (13 +/- 3%ID/g) did not differ significantly from tumor uptake (9 +/- 3%ID/g). Tumor uptake was stable between 1 and 3 h followed by a slow decline. The highest absorbed dose was in kidneys, followed by organs and tissues in abdomen.Discussion: Biodistribution studies in mice demonstrated that targeting properties of [Lu-177]Lu-BQ7876 are not inferior to properties of [Lu-177]Lu-PSMA-617, but do not offer any decisive advantages.
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| 5. |
- Abouzayed, Ayman, et al.
(författare)
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Preclinical Evaluation of 99mTc-Labeled GRPR Antagonists maSSS/SES-PEG2-RM26 for Imaging of Prostate Cancer
- 2021
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Ingår i: Pharmaceutics. - : MDPI. - 1999-4923 .- 1999-4923. ; 13:2
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Tidskriftsartikel (refereegranskat)abstract
- Background: Gastrin-releasing peptide receptor (GRPR) is an important target for imaging of prostate cancer. The wide availability of single-photon emission computed tomography/computed tomography (SPECT/CT) and the generator-produced 99mTc can be utilized to facilitate the use of GRPR-targeting radiotracers for diagnostics of prostate cancers.Methods: Synthetically produced mercaptoacetyl-Ser-Ser-Ser (maSSS)-PEG2-RM26 and mercaptoacetyl-Ser-Glu-Ser (maSES)-PEG2-RM26 (RM26 = d-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2) were radiolabeled with 99mTc and characterized in vitro using PC-3 cells and in vivo, using NMRI or PC-3 tumor bearing mice. SPECT/CT imaging and dosimetry calculations were performed for [99mTc]Tc-maSSS-PEG2-RM26.Results: Peptides were radiolabeled with high yields (>98%), demonstrating GRPR specific binding and slow internalization in PC-3 cells. [99mTc]Tc-maSSS-PEG2-RM26 outperformed [99mTc]Tc-maSES-PEG2-RM26 in terms of GRPR affinity, with a lower dissociation constant (61 pM vs 849 pM) and demonstrating higher tumor uptake. [99mTc]Tc-maSSS-PEG2-RM26 had tumor-to-blood, tumor-to-muscle, and tumor-to-bone ratios of 97 ± 56, 188 ± 32, and 177 ± 79, respectively. SPECT/CT images of [99mTc]Tc-maSSS-PEG2-RM26 clearly visualized the GRPR-overexpressing tumors. The dosimetry estimated for [99mTc]Tc-maSSS-PEG2-RM26 showed the highest absorbed dose in the small intestine (1.65 × 10−3 mGy/MBq), and the effective dose is 3.49 × 10−3 mSv/MBq.Conclusion: The GRPR antagonist maSSS-PEG2-RM26 is a promising GRPR-targeting agent that can be radiolabeled through a single-step with the generator-produced 99mTc and used for imaging of GRPR-expressing prostate cancer.
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| 6. |
- Abouzayed, Ayman, et al.
(författare)
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The GRPR Antagonist [Tc-99m]Tc-maSSS-PEG(2)-RM26 towards Phase I Clinical Trial : Kit Preparation, Characterization and Toxicity
- 2023
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Ingår i: Diagnostics. - : MDPI AG. - 2075-4418. ; 13:9, s. 1611-
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Tidskriftsartikel (refereegranskat)abstract
- Gastrin-releasing peptide receptors (GRPRs) are overexpressed in the majority of primary prostate tumors and in prostatic lymph node and bone metastases. Several GRPR antagonists were developed for SPECT and PET imaging of prostate cancer. We previously reported a preclinical evaluation of the GRPR antagonist [Tc-99m]Tc-maSSS-PEG2-RM26 (based on [D-Phe(6), Sta(13), Leu(14)-NH2]BBN(6-14)) which bound to GRPR with high affinity and had a favorable biodistribution profile in tumor-bearing animal models. In this study, we aimed to prepare and test kits for prospective use in an early-phase clinical study. The kits were prepared to allow for a one-pot single-step radiolabeling with technetium-99m pertechnetate. The kit vials were tested for sterility and labeling efficacy. The radiolabeled by using the kit GRPR antagonist was evaluated in vitro for binding specificity to GRPR on PC-3 cells (GRPR-positive). In vivo, the toxicity of the kit constituents was evaluated in rats. The labeling efficacy of the kits stored at 4 degrees C was monitored for 18 months. The biological properties of [Tc-99m]Tc-maSSS-PEG2-RM26, which were obtained after this period, were examined both in vitro and in vivo. The one-pot (gluconic acid, ethylenediaminetetraacetic acid, stannous chloride, and maSSS-PEG(2)-RM26) single-step radiolabeling with technetium-99m was successful with high radiochemical yields (>97%) and high molar activities (16-24 MBq/nmol). The radiolabeled peptide maintained its binding properties to GRPR. The kit constituents were sterile and non-toxic when tested in living subjects. In conclusion, the prepared kit is considered safe in animal models and can be further evaluated for use in clinics.
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| 7. |
- Ahlgren, Sara, 1979-
(författare)
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Molecular Radionuclide Imaging Using Site-specifically Labelled Recombinant Affibody Molecules : Preparation and Preclinical Evaluation
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Radionuclide molecular imaging is an emerging multidisciplinary technique that is used in modern medicine to visualise diseases at cellular and molecular levels. This thesis is based on five papers (I-V) and focuses on the development of site-specific radiolabelled recombinant anti-HER2 Affibody molecules and preclinical evaluations in vitro and in vivo of the labelled conjugates. This work is part of a preclinical development of an Affibody molecule-based tracer for molecular imaging of HER2 expressing tumours. Papers I and II report the evaluation of the Affibody molecule ZHER2:2395-C, site-specifically labelled with the radiometals 111In (for SPECT) and 57Co (as a surrogate for 55Co, suitable for PET applications) using a thiol reactive DOTA derivative as a chelator. Both conjugates demonstrated very suitable biodistribution properties, enabling high contrast imaging just a few hours after injection. Papers III and IV report the development and optimization of a technique for site-specific labelling of ZHER2:2395-C with 99mTc using an N3S chelating peptide sequence. 99mTc-ZHER2:2395-C demonstrated high and specific tumour uptake and rapid clearance of non-bound tracer from the blood, resulting in high tumour-to-non-tumour ratios shortly after injection, enabling high contrast imaging. In addition, in the study described in paper IV, freeze-dried kits previously developed for 99mTc-labelling were optimised, resulting in the development of a kit in which all the reagents and protein needed for labelling of ZHER2:2395-C with 99mTc were contained in a single vial. Paper V reports the evaluation of an anti-HER2 Affibody molecule, ABY-025, with a fundamentally re-engineered scaffold. Despite the profound re-engineering, the biodistribution pattern of 111In-ABY-025 was very similar to that of two variants of the parental molecule. It seems reasonable to believe that these results will also be applicable to Affibody molecules towards other targets. Hopefully, this work will also be helpful in the development of other small proteinaceous tracers.
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| 8. |
- Altai, Mohamed, et al.
(författare)
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188Re-ZHER2:V2, a promising affibody-based targeting agent against HER2-expressing tumors : preclinical assessment
- 2014
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Ingår i: Journal of nuclear medicine : official publication, Society of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 55:11, s. 8-1842
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Tidskriftsartikel (refereegranskat)abstract
- UNLABELLED: Affibody molecules are small (7 kDa) nonimmunoglobulin scaffold proteins with favorable tumor-targeting properties. Studies concerning the influence of chelators on biodistribution of (99m)Tc-labeled Affibody molecules demonstrated that the variant with a C-terminal glycyl-glycyl-glycyl-cysteine peptide-based chelator (designated ZHER2:V2) has the best biodistribution profile in vivo and the lowest renal retention of radioactivity. The aim of this study was to evaluate (188)Re-ZHER2:V2 as a potential candidate for radionuclide therapy of human epidermal growth factor receptor type 2 (HER2)-expressing tumors.METHODS: ZHER2:V2 was labeled with (188)Re using a gluconate-containing kit. Targeting of HER2-overexpressing SKOV-3 ovarian carcinoma xenografts in nude mice was studied for a dosimetry assessment.RESULTS: Binding of (188)Re-ZHER2:V2 to living SKOV-3 cells was demonstrated to be specific, with an affinity of 6.4 ± 0.4 pM. The biodistribution study showed a rapid blood clearance (1.4 ± 0.1 percentage injected activity per gram [%ID/g] at 1 h after injection). The tumor uptake was 14 ± 2, 12 ± 2, 5 ± 2, and 1.8 ± 0.5 %IA/g at 1, 4, 24, and 48 h after injection, respectively. The in vivo targeting of HER2-expressing xenografts was specific. Already at 4 h after injection, tumor uptake exceeded kidney uptake (2.1 ± 0.2 %IA/g). Scintillation-camera imaging showed that tumor xenografts were the only sites with prominent accumulation of radioactivity at 4 h after injection. Based on the biokinetics, a dosimetry evaluation for humans suggests that (188)Re-ZHER2:V2 would provide an absorbed dose to tumor of 79 Gy without exceeding absorbed doses of 23 Gy to kidneys and 2 Gy to bone marrow. This indicates that future human radiotherapy studies may be feasible.CONCLUSION: (188)Re-ZHER2:V2 can deliver high absorbed doses to tumors without exceeding kidney and bone marrow toxicity limits.
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| 9. |
- Bezverkhniaia, Ekaterina, et al.
(författare)
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Preclinical Evaluation of a Novel High-Affinity Radioligand [99mTc]Tc-BQ0413 Targeting Prostate-Specific Membrane Antigen (PSMA)
- 2023
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Ingår i: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 24:24
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Tidskriftsartikel (refereegranskat)abstract
- Radionuclide imaging using radiolabeled inhibitors of prostate-specific membrane antigen (PSMA) can be used for the staging of prostate cancer. Previously, we optimized the Glu-urea-Lys binding moiety using a linker structure containing 2-napththyl-L-alanine and L-tyrosine. We have now designed a molecule that contains mercaptoacetyl-triglutamate chelator for labeling with Tc-99m (designated as BQ0413). The purpose of this study was to evaluate the imaging properties of [Tc-99m]Tc-BQ0413. PSMA-transfected PC3-pip cells were used to evaluate the specificity and affinity of [Tc-99m]Tc-BQ0413 binding in vitro. PC3-pip tumor-bearing BALB/C nu/nu mice were used as an in vivo model. [Tc-99m]Tc-BQ0413 bound specifically to PC3-pip cells with an affinity of 33 +/- 15 pM. In tumor-bearing mice, the tumor uptake of [Tc-99m]Tc-BQ0413 (38 +/- 6 %IA/g in PC3-pip 3 h after the injection of 40 pmol) was dependent on PSMA expression (3 +/- 2 %IA/g and 0.9 +/- 0.3 %IA/g in PSMA-negative PC-3 and SKOV-3 tumors, respectively). We show that both unlabeled BQ0413 and the commonly used binder PSMA-11 enable the blocking of [Tc-99m]Tc-BQ0413 uptake in normal PSMA-expressing tissues without blocking the uptake in tumors. This resulted in an appreciable increase in tumor-to-organ ratios. At the same injected mass (5 nmol), the use of BQ0413 was more efficient in suppressing renal uptake than the use of PSMA-11. In conclusion, [Tc-99m]Tc-BQ0413 is a promising probe for the visualization of PSMA-positive lesions using single-photon emission computed tomography (SPECT).
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| 10. |
- Bragina, O. D., et al.
(författare)
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Possibilities of predicting the HER2 / neu status in a primary tumor in breast cancer patients using (99)mTc-DARPinG3
- 2022
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Ingår i: BYULLETEN SIBIRSKOY MEDITSINY. - : SIBERIAN STATE MEDICAL UNIV. - 1682-0363 .- 1819-3684. ; 21:4, s. 6-12
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Tidskriftsartikel (refereegranskat)abstract
- Aim: To determine informative prognostic criteria for assessing the HER2 / neu status in primary breast cancer using 99mTc-DARPinG3.Materials and methods; The study included 10 patients with breast cancer (T1-4N0-2M0) before systemic therapy, who underwent a radionuclide study using 99mTc-DARPinG3 at a dose of 3,000 & mu;g. Five patients were characterized by HER2 / neu overexpression in primary breast cancer, whereas 5 patients were HER2-negative. For all patients, morphological and immunohistochemical studies and fluorescence in situ hybridization (FISH) of the primary tu-mor nodule were carried out. Single-photon emission computed tomography (SPECT) of the chest was performed for all patients 4 hours after the injection of 99mTc-DARPinG3.Results: The total activity of 99mTc-DARPinG3 was 522.4 & PLUSMN; 341.8 MBq. The comparative analysis showed that higher uptake of the labeled protein in HER2-positive breast cancer was significant (p = 0.0159, Mann - Whitney U test). The analysis of the ratios showed significant differences in the tumor-to-background ratios in patients with HER2-positive breast cancer (p < 0.0159, Mann - Whitney U test). Based on the logistic regression analysis, a mathematical model was developed to predict the status of HER2 / neu in primary breast cancer patients (specificity and sensitivity 100%; p = 0.0004) using 99mTc-DARPinG3 at a dose of 3,000 mcg 4 hours after the injection of the radiopharmaceutical.Conclusion: The results of the study allow to consider the tumor-to-background ratio 4 hours after the injection of 99mTc-DARPinG3 as an additional prognostic parameter for determining the HER2 / neu status in primary breast cancer.
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