| 1. |
- Ahlgren, Sara, et al.
(författare)
-
Targeting of HER2-Expressing Tumors Using 111In-ABY-025, a Second-Generation Affibody Molecule with a Fundamentally Reengineered Scaffold
- 2010
-
Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 51:7, s. 1131-1138
-
Tidskriftsartikel (refereegranskat)abstract
- Overexpression of HER2 in breast carcinomas predicts response to trastuzumab therapy. Affibody molecules based on a non-immunoglobulin scaffold have demon-strated high potential for in vivo molecular imaging of HER2-expressing tumors. Re-engineering of the molecular scaffold has led to a second generation of optimized Affibody molecules, having a surface distinctly different from the parental protein domain from staphylococcal protein A. The new tracer showed further increased melting point, stability and overall hydrophilicity compared to the parental molecule, and was shown to be more amenable for chemical peptide synthesis. The goal of this study was to assess potential effects of this extensive re-engineering on HER2 targeting, using ABY-025, a DOTA conjugated variant of the novel tracer. Methods: 111In-ABY-025 was compared with previously evaluated parent HER2-binding Affibody tracers in vitro and in vivo. The in vivo behavior was further evaluated in mice bearing SKOV-3 xenografts, in rats and in cynomolgus macaques. Results: 111In-ABY-025 bound specifically to HER2 in vitro and in vivo. Direct comparison with the previous generation of HER2-binding tracers showed that ABY-025 retained excellent targeting properties. Rapid blood clearance was shown in mice, rats and macaques. A highly specific tumor uptake of 16.7 ± 2.5 %IA/g was seen at 4 h after injection. The tumor-to-blood ratio was 6.3 at 0.5 h, 88 at 4 h, and increased up to 3 days after injection. Gamma camera imaging of tumors was already possible 0.5 h after injection. Furthermore, repeated i.v. administration of ABY-025 did not induce antibody formation in rats. Conclusions: The biodistribution of 111In-ABY-025 was in remarkably good agreement with the parent tracers, despite profound re-engineering of the non-binding surface. The molecule displayed rapid blood clearance in all species investigated and excellent targeting capacity in tumor bearing mice, leading to high tumor-to-organ-ratios and high contrast imaging shortly after injection.
|
|
| 2. |
- Ahlgren, Sara, et al.
(författare)
-
Targeting of HER2-expressing tumors with a site-specifically 99mTc-labeled recombinant affibody molecule, ZHER2:2395, with C-terminally engineered cysteine
- 2009
-
Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 50:5, s. 781-789
-
Tidskriftsartikel (refereegranskat)abstract
- The detection of human epidermal growth factor receptor type 2 (HER2) expression in malignant tumors provides important information influencing patient management. Radionuclide in vivo imaging of HER2 may permit the detection of HER2 in both primary tumors and metastases by a single noninvasive procedure. Small (7 kDa) high-affinity anti-HER2 Affibody molecules may be suitable tracers for SPECT visualization of HER2-expressing tumors. The use of generator-produced (99m)Tc as a label would facilitate the prompt translation of anti-HER2 Affibody molecules into use in clinics. METHODS: A C-terminal cysteine was introduced into the Affibody molecule Z(HER2:342) to enable site-specific labeling with (99m)Tc. Two recombinant variants, His(6)-Z(HER2:342)-Cys (dissociation constant [K(D)], 29 pM) and Z(HER2:2395)-Cys, lacking a His tag (K(D), 27 pM), were labeled with (99m)Tc in yields exceeding 90%. The binding specificity and the cellular processing of Affibody molecules were studied in vitro. Biodistribution and gamma-camera imaging studies were performed in mice bearing HER2-expressing xenografts. RESULTS: (99m)Tc-His(6)-Z(HER2:342)-Cys was capable of targeting HER2-expressing SKOV-3 xenografts in SCID mice, but the liver radioactivity uptake was high. A series of comparative biodistribution experiments indicated that the presence of the His tag caused elevated accumulation in the liver. (99m)Tc-Z(HER2:2395)-Cys, not containing a His tag, showed low uptake in the liver and high and specific uptake in HER2-expressing xenografts. Four hours after injection, the radioactivity uptake values (percentage of injected activity per gram of tissue [%IA/g]) were 6.9 +/- 2.5 (mean +/- SD) %IA/g in LS174T xenografts (moderate level of HER2 expression) and 15 +/- 3 %IA/g in SKOV-3 xenografts (high level of HER2 expression). The corresponding tumor-to-blood ratios were 88 +/- 24 and 121 +/- 24, respectively. Both LS174T and SKOV-3 xenografts were clearly visualized with a clinical gamma-camera 1 h after injection of (99m)Tc-Z(HER2:2395)-Cys. CONCLUSION: The Affibody molecule (99m)Tc-Z(HER2:2395)-Cys is a promising tracer for SPECT visualization of HER2-expressing tumors.
|
|
| 3. |
- Alhuseinalkhudhur, Ali, et al.
(författare)
-
Human Epidermal Growth Factor Receptor 2-Targeting [68Ga]Ga-ABY-025 PET/CT Predicts Early Metabolic Response in Metastatic Breast Cancer.
- 2023
-
Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667. ; 64:9, s. 1364-1370
-
Tidskriftsartikel (refereegranskat)abstract
- Imaging using the human epidermal growth factor receptor 2 (HER2)-binding tracer 68Ga-labeled ZHER2:2891-Cys-MMA-DOTA ([68Ga]Ga-ABY-025) was shown to reflect HER2 status determined by immunohistochemistry and in situ hybridization in metastatic breast cancer (MBC). This single-center open-label phase II study investigated how [68Ga]Ga-ABY-025 uptake corresponds to biopsy results and early treatment response in both primary breast cancer (PBC) planned for neoadjuvant chemotherapy and MBC. Methods: Forty patients with known positive HER2 status were included: 19 with PBC and 21 with MBC (median, 3 previous treatments). [68Ga]Ga-ABY-025 PET/CT, [18F]F-FDG PET/CT, and core-needle biopsies from targeted lesions were performed at baseline. [18F]F-FDG PET/CT was repeated after 2 cycles of therapy to calculate the directional change in tumor lesion glycolysis (Δ-TLG). The largest lesions (up to 5) were evaluated in all 3 scans per patient. SUVs from [68Ga]Ga-ABY-025 PET/CT were compared with the biopsied HER2 status and Δ-TLG by receiver operating characteristic analyses. Results: Trial biopsies were HER2-positive in 31 patients, HER2-negative in 6 patients, and borderline HER2-positive in 3 patients. The [68Ga]Ga-ABY-025 PET/CT cutoff SUVmax of 6.0 predicted a Δ-TLG lower than -25% with 86% sensitivity and 67% specificity in soft-tissue lesions (area under the curve, 0.74 [95% CI, 0.67-0.82]; P = 0.01). Compared with the HER2 status, this cutoff resulted in clinically relevant discordant findings in 12 of 40 patients. Metabolic response (Δ-TLG) was more pronounced in PBC (-71% [95% CI, -58% to -83%]; P < 0.0001) than in MBC (-27% [95% CI, -16% to -38%]; P < 0.0001), but [68Ga]Ga-ABY-025 SUVmax was similar in both with a mean SUVmax of 9.8 (95% CI, 6.3-13.3) and 13.9 (95% CI, 10.5-17.2), respectively (P = 0.10). In multivariate analysis, global Δ-TLG was positively associated with the number of previous treatments (P = 0.0004) and negatively associated with [68Ga]Ga-ABY-025 PET/CT SUVmax (P = 0.018) but not with HER2 status (P = 0.09). Conclusion: [68Ga]Ga-ABY-025 PET/CT predicted early metabolic response to HER2-targeted therapy in HER2-positive breast cancer. Metabolic response was attenuated in recurrent disease. [68Ga]Ga-ABY-025 PET/CT appears to provide an estimate of the HER2 expression required to induce tumor metabolic remission by targeted therapies and might be useful as an adjunct diagnostic tool.
|
|
| 4. |
- Altai, Mohamed, et al.
(författare)
-
188Re-ZHER2:V2, a promising affibody-based targeting agent against HER2-expressing tumors : preclinical assessment
- 2014
-
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
-
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.
|
|
| 5. |
- Altai, Mohamed, et al.
(författare)
-
Feasibility of Affibody-Based Bioorthogonal Chemistry Mediated Radionuclide Pretargeting
- 2016
-
Ingår i: Journal of Nuclear Medicine. - : SOC NUCLEAR MEDICINE. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 57:3, s. 431-436
-
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.
|
|
| 6. |
- Altai, Mohamed, et al.
(författare)
-
Pretargeted Imaging and Therapy
- 2017
-
Ingår i: Journal of Nuclear Medicine. - : SOC NUCLEAR MEDICINE INC. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 58:10, s. 1553-1559
-
Tidskriftsartikel (refereegranskat)abstract
- In vivo pretargeting stands as a promising approach to harnessing the exquisite tumor-targeting properties of antibodies for nuclear imaging and therapy while simultaneously skirting their pharmacokinetic limitations. The core premise of pretargeting lies in administering the targeting vector and radioisotope separately and having the 2 components combine within the body. In this manner, pretargeting strategies decrease the circulation time of the radioactivity, reduce the uptake of the radionuclide in healthy nontarget tissues, and facilitate the use of short-lived radionuclides that would otherwise be incompatible with antibody-based vectors. In this short review, we seek to provide a brief yet informative survey of the 4 preeminent mechanistic approaches to pretargeting, strategies predicated on streptavidin and biotin, bispecific antibodies, complementary oligonucleotides, and bioorthogonal click chemistry.
|
|
| 7. |
- Baum, Richard P, et al.
(författare)
-
Molecular imaging of HER2-expressing malignant tumors in breast cancer patients using synthetic 111In- or 68Ga-labeled affibody molecules
- 2010
-
Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 51:6, s. 892-897
-
Tidskriftsartikel (refereegranskat)abstract
- The clinical utility of a human epidermal growth factor receptor 2 (HER2)-targeting Affibody molecule for detection and characterization of HER2-positive lesions was investigated in patients with recurrent metastatic breast cancer. METHODS: Three patients received (111)In- or (68)Ga-labeled DOTA(0)-Z(HER2:342-pep2) (ABY-002). gamma-Camera, SPECT, or PET/CT images were compared with earlier (18)F-FDG PET/CT results. RESULTS: Administration of radiolabeled ABY-002 was well tolerated. Blood kinetics of radiolabeled ABY-002 showed a first half-life of 4-14 min, second half-life of 1-4 h, and third half-life of 12-18 h. Radiolabeled ABY-002 detected 9 of 11 (18)F-FDG-positive metastases as early as 2-3 h after injection. CONCLUSION: Molecular imaging using (111)In- or (68)Ga-labeled ABY-002 has the potential to localize metastatic lesions in vivo, adds qualitative information not available today by conventional imaging techniques, and may allow the HER2 status to be determined for metastases not amenable to biopsy. To our knowledge, this is the first report on clinical imaging data obtained with a non-immunoglobulin-based scaffold protein.
|
|
| 8. |
- Bergström, Mats, et al.
(författare)
-
In vitro and animal validation of bromine-76-bromodeoxyuridine as a proliferation marker
- 1998
-
Ingår i: Journal of Nuclear Medicine. - 0161-5505 .- 1535-5667. ; 39:7, s. 1273-9
-
Tidskriftsartikel (refereegranskat)abstract
- The potential of 76Br-bromodeoxyuridine as a PET tracer for characterizing proliferation potential was investigated in multicellular tumor aggregates and in healthy rats and pigs. METHODS: Bromine-76-bromide was produced by proton irradiation of a 76Se-enriched target using a 17-MeV cyclotron and recovered by thermal diffusion. Bromine-76-BrdU was prepared from the corresponding trimethylstannate by an oxidative bromination. Multicellular aggregates from a carcinoid cell line and two bladder cancer cell lines were co-incubated with 76Br-BrdU and 3H-thymidine and the uptake and DNA incorporation analyzed. About 0.5 MBq 76Br-BrdU were injected in the tail vein of unanaesthetised Sprague-Dawley rats. Two to 36 hr later they were decapitated and the radioactivity concentration and fraction of radioactivity incorporated into DNA determined in five different organs and the blood. Parallel studies were performed in animals pretreated with hydroxyurea. In separate experiments, rats were given an injection of 76Br-bromide and organ uptake was evaluated after 20 hr. PET studies were performed in two pigs and the uptake in different organs was investigated after injection of 76Br-BrdU. In these studies, diuresis was induced by furosemide and mannitol and radioactivity in blood and organs was followed during 10 hr. RESULTS: In the cell aggregates, 30%-90% of the radioactivity was extracted in the DNA fraction. A good correlation was found between 76Br-BrdU and 3H-thymidine with respect to total uptake and DNA fraction. The DNA fraction increased from 2-10 hr after incubation. With in vivo injection in the rat, relatively high uptake of radioactivity was found in all organs, unrelated to the degree of DNA synthesis. However, inhibition by hydroxyurea occurred only in the spleen and intestines, organs which also showed a high degree of incorporation of 76Br-BrdU into DNA. In the pig, the highest in vivo uptake was observed in the red bone marrow and the intestines. In these organs, 70%-80% of the radioactivity was recovered in the DNA fraction. The concentration of radioactivity in the heart, liver and kidney was 3-10 times lower, and here the DNA fraction accounted for 10%-20% of the radioactivity. The decay-corrected radioactivity in blood and nonproliferating organs decreased with diuresis with a half-life of 13 and 16 hr, respectively. CONCLUSION: It is suggested that the radioactivity uptake as seen after the administration of 76Br-BrdU, is constituted by two parts: one relating to incorporation into DNA and one existing as free 76Br- or metabolites of 76Br-BrdU. If sufficient time has passed, 76Br- dominates other metabolites. A correct assessment of DNA-incorporated radioactivity using PET with 76Br-BrdU is not trivial and can only be made with due correction for 76Br-, using either a complementary investigation after hydroxyurea pretreatment (in animal studies) or a separate 76Br-bromide investigation. Alternatively, the free bromide can be eliminated partially through forced diuresis.
|
|
| 9. |
- Bragina, Olga, et al.
(författare)
-
Phase I study of 99mTc-ADAPT6, a scaffold protein-based probe for visualization of HER2 expression in breast cancer
- 2021
-
Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 62:4, s. 493-499
-
Tidskriftsartikel (refereegranskat)abstract
- Radionuclide molecular imaging of human epidermal growth factor (HER2) expression may be helpful to stratify breast and gastroesophageal cancer patients for HER2-targeting therapies. ADAPTs (albumin-binding domain derived affinity proteins) are a new type of small (46-59 amino acids) proteins useful as probes for molecular imaging. The aim of this first-in-human study was to evaluate biodistribution, dosimetry, and safety of the HER2-specific 99mTc-ADAPT6.METHODS: Twenty-nine patients with primary breast cancerwere included. In 22 patients with HER2-positive (n = 11) or HER2-negative (n = 11) histopathology an intravenous injection with 385±125 MBq 99mTc-ADAPT6 was performed, randomized to an injected protein mass of either 500 µg (n = 11) or 1000 µg (n = 11). Planar scintigraphy followed by SPECT imaging was performed after 2, 4, 6 and 24 h. An additional cohort (n = 7) was injected with 165±29 MBq (injected protein mass 250 µg) and imaging was performed after 2 h only.RESULTS: Injections of 99mTc-ADAPT6 at all injected mass levels were well tolerated and not associated with adverse effects. 99mTc-ADAPT6 cleared rapidly from blood and most other tissues. The normal organs with the highest accumulation were kidney, liver and lung. Effective doses were 0.009±0.002 and 0.010±0.003 mSv/MBq for injected protein masses of 500 and 1000 µg, respectively. Injection of 500 µg resulted in excellent discrimination between HER2-positive and HER2-negative tumors already 2 h after injection (tumor-to-contralateral breast ratio was 37±19 vs 5±2, p<0.01). The tumor-to-contralateral breast ratios for HER2-positive tumors were significantly (p<0.05) higher for injected mass of 500 µg than for both 250 and 1000 µg.CONCLUSION: Injections of 99mTc-ADAPT6 are safe and associated with low absorbed and effective doses. Protein dose of 500 µg is preferable for discrimination between tumors with high and low expression of HER2. Further studies are justified to evaluate if 99mTc-ADAPT6 can be used as an imaging probe for stratification of patients for HER2-targeting therapy in the areas where PET imaging is not readily available.
|
|
| 10. |
- Bragina, Olga, et al.
(författare)
-
Phase I Trial of 99mTc-(HE)3-G3, a DARPin-Based Probe for Imaging of HER2 Expression in Breast Cancer
- 2022
-
Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 63:4, s. 528-535
-
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.
|
|
