| 1. |
- Gedda, Lars, et al.
(författare)
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Experimental radionuclide therapy of HER2-expressing xenografts using two-step targeting Nuclisome-particles
- 2012
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 53:3, s. 480-487
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Tidskriftsartikel (refereegranskat)abstract
- The therapeutic potential of Auger-electron emitting radionuclides is strongly dependent on their close vicinity to DNA, since the energy deposition is mainly localized within a few cubic nanometers around the site of decay. Thus, apart from specificity, successful tumor therapy relies on a nuclear delivery strategy. We recently presented a two-step targeting strategy to transport Auger-electron-emitting radionuclides into the cell nucleus by means of nuclide-filled liposomes (Nuclisome particles), that is, polyethylene glycol-stabilized, tumor-cell-targeting liposomes loaded with (125)I-labeled anthracyclines. In the present study, the survival of mice intraperitoneally inoculated with human HER2-expressing SKOV-3 tumor cells and treated with HER2-targeting Nuclisome particles was studied.METHODS:BALB/c nu/nu mice were inoculated with 10(7) SKOV-3 cells intraperitoneally and thereafter directly injected with Nuclisome particles with increasing specific radioactivity. Groups of 10-12 mice were treated with 0.01 MBq/mouse up to 2 MBq/mouse, and survival was monitored and compared with that in control groups (n = 33). Organs were analyzed for HER2 expression and radiotoxic effects histologically. Absorbed doses were estimated using dose factors from the online Radiation Dose Assessment Resource model.RESULTS:The results showed a clear correlation between administered radioactive dose and survival. No such dose-dependent survival was observed for mice treated with Nuclisome particles lacking HER2-targeting ability. With HER2-targeting Nuclisome particles, a significant increase in survival, compared with that of untreated control mice, could already be seen at an administered activity of 0.1 MBq/mouse (P = 0.0301). At the highest activity administered, 2 MBq/mouse (P < 0.0001), 70% of the mice survived the study and most were tumor-free. Neither macroscopic nor microscopic radiotoxic side effects were observed. Dosimetric calculations, assuming nonreceptor targeting, revealed that the radioactive doses to normal tissues were low.CONCLUSION:Taken together the results show that with successful targeting to the tumor-cell nucleus it is possible to obtain a therapeutic effect from Auger-electron-emitting radionuclides administered at radioactive doses low enough to spare normal tissue from radiotoxic side effects.
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| 2. |
- Lubberink, Mark, et al.
(författare)
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110mIn-DTPA-D-Phe1-octreotide for imaging of neuroendocrine tumors with PET
- 2002
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Ingår i: Journal of Nuclear Medicine. - 0161-5505 .- 1535-5667. ; 43:10, s. 1391-7
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Tidskriftsartikel (refereegranskat)abstract
- The somatostatin analog diethylenetriaminepentaacetic acid (DTPA)-D-Phe1-octreotide labeled with 111In has been applied extensively for diagnosis of neuroendocrine tumors using SPECT or planar scintigraphy. However, the spatial resolution of planar scintigraphy and SPECT prohibits imaging of small tumors, and the quantification accuracy of both methods is limited. METHODS: We developed a method to prepare the positron-emitting radiopharmaceutical 110mIn-DTPA-D-Phe1-octreotide based on a commercially available kit. Phantom studies were done to investigate and compare the performance of 110mIn PET and 111In SPECT. A clinical imaging study using 110mIn-DTPA-D-Phe1-octreotide and PET was done to investigate the application of this radiopharmaceutical. RESULTS: An almost 3-fold better resolution and much better quantitative capabilities were found for 110mIn PET than for 111In SPECT. The clinical imaging study demonstrated the potential use of 110mIn-octreotide in PET to image tumors and quantify radioactivity uptake in humans using (110m)In-DTPA-D-Phe1-octreotide. CONCLUSION: PET with 110mIn-DTPA-D-Phe1-octreotide greatly improved detection of small tumors and offers a possibility of more accurate quantification of tumor uptake than can be obtained with 111In-DTPA-D-Phe1-octreotide and SPECT.
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| 3. |
- Lövqvist, Anna, et al.
(författare)
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Comparative PET imaging of experimental tumors with bromine-76-labeled antibodies, fluorine-18-fluorodeoxyglucose and carbon-11-methionine
- 1997
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Ingår i: Journal of Nuclear Medicine. - 0161-5505 .- 1535-5667. ; 38:7, s. 1029-1035
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Tidskriftsartikel (refereegranskat)abstract
- The potential of a 76Br-labeled anti-carcinoembryonic antigen monoclonal antibody (MAb), 38S1, as tumor-imaging agent for PET was investigated in a comparative experimental study with [18F]fluorodeoxyglucose ([18F]FDG) and L-[methyl-11C]methionine ([11C]Met). METHODS: The three radiotracers were administered to nude rats carrying subcutaneous xenografts or liver metastases from a human colonic carcinoma. Tracer biodistribution was evaluated by PET imaging and radioactivity measurement of dissected tissues and also by whole-body autoradiography for subcutaneous xenografts. RESULTS: For PET imaging of subcutaneous tumors, 76Br-38S1 proved superior to the other radiotracers. Tumor-to-tissue ratios were, except for the tumor-to-blood ratio, generally higher for 76Br-labeled MAb than for [18F]FDG and [11C]Met. Liver metastases were imaged with PET using both 76Br-38S1 and [18F]FDG, and the metastases-to-liver ratios of dissected samples were not significantly different for the two radiotracers. CONCLUSION: The tumor-imaging capacity of 76Br-labeled MAb 38S1 was superior to [18F]FDG and [11C]Met in the subcutaneous tumor model, whereas 76Br-38S1 and [18F]FDG were equally successful for the identification of liver metastases.
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| 4. |
- Lövqvist, Anna, et al.
(författare)
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Pharmacokinetics and experimental PET imaging of a bromine-76-labeled monoclonal anti-CEA antibody
- 1997
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Ingår i: Journal of Nuclear Medicine. - 0161-5505 .- 1535-5667. ; 38:3, s. 395-401
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Tidskriftsartikel (refereegranskat)abstract
- Bromine-76 is potentially useful as a radiolabel for monoclonal antibodies (MAbs) in PET imaging. The purpose of the present study was to evaluate the 76Br-labeled anticarcinoembryonic antigen (-CEA) MAb 38S1 as a tumor imaging agent in an experimental tumor model and to study the pharmacokinetics of 76Br-38S1 in comparison with 125I-38S1. METHODS: Nude rats carrying human colon carcinoma xenografts were co-injected with directly labeled 76Br-38S1 and 125I-38S1. Biodistribution of labeled 38S1 was monitored for 4 days after administration, in the case of 76Br activity, including PET imaging. In addition, catabolism of radiolabeled MAbs was analyzed by gel filtration chromatography of blood plasma and homogenized tissues. RESULTS: Tumor sites could be readily identified by PET imaging from 46 hr after administration of 76Br-38S1 and onwards. The concentration of 76Br activity in tumors, blood and most normal tissues was higher than the corresponding 125I concentration at all time points. This was mainly due to catabolism of radiolabeled MAb, resulting in free radiohalides, of which 76Br- was retained in contrast to the rapidly excreted 125I- ion. CONCLUSION: Bromine-76-labeled anti-CEA MAbs may be applied for experimental tumor imaging with PET.
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| 5. |
- Orlova, Anna, et al.
(författare)
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Site-specific radiometal labeling and improved biodistribution using ABY-027, a novel HER2-targeting affibody molecule-albumin-binding domain fusion protein
- 2013
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 54:6, s. 961-968
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Tidskriftsartikel (refereegranskat)abstract
- Because of their better penetration, smaller targeting proteins may be superior to antibodies for radioimmunotherapy of solid tumors. Therefore, Affibody molecules (6.5 kDa) have a potential for being suitable as targeted moiety for radiolabeled therapeutic proteins. Previous studies have demonstrated that a fusion of an Affibody molecule with an albumin-binding domain (ABD) provides a strong noncovalent binding to albumin in vivo. This strong noncovalent binding can be used for reduction of the renal uptake of the Affibody molecule while maintaining a size smaller than that of an antibody, which is important when using residualizing radionuclide labels conjugated to Affibody molecules. The goal of this study was to design and evaluate a new targeting Affibody - ABD fusion protein with improved biodistribution properties for radionuclide therapy. Methods: A novel Affibody-based construct, Z HER2:2891-ABD035-DOTA (ABY-027), was created by fusion of the reengineered HER2-binding Affibody molecule ZHER2:2891 to the N terminus of the high-affinity ABD035, and a maleimido-derivative of DOTA was conjugated at the C terminus of the construct. Binding and processing of 177Lu-ABY-027 by HER2-expressing cells were evaluated in vitro. Targeting of HER2-expressing SKOV-3 xenografts was evaluated in BALB/C nu/nu mice and compared with targeting of previously reported ABD-(Z HER2:342)2. Results: The binding affinity (dissociation constant) of ABY-027 to HER2 (74 pM) was the same as for the parental Z HER2:2891 (76 pM). ABY-027 was stably labeled with 177Lu and 111In with preserved specific binding to HER2-expressing cells in vitro. In vivo receptor saturation experiments demonstrated that targeting of SKOV-3 xenografts in BALB/C nu/nu mice was HER2-specific. 177Lu-ABY- 027 demonstrated substantially (2- to 3-fold) lower renal and hepatic uptake than previously assessed HER2-specific Affibody-based albumin-binding agents. Tumor uptake of radiolabeled ABY-027 at 48 h after injection was 2-fold higher than that for previously reported ABD-(ZHER2:342)2. Conclusion: An optimized molecular design of an ABD fusion protein resulted in an Affibody molecule construct with better properties for therapy. Fully preserved in vivo targeting of the fusion protein was shown in xenografted mice. Site-specific coupling of DOTA provides a uniform conjugate and creates the potential for labeling with a broad range of therapeutic radionuclides. The biodistribution of 177Lu-ABY-027 in a murine model suggests it is more suitable for therapy than alternative approaches.
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| 6. |
- Sandström, Mattias, et al.
(författare)
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Comparative Biodistribution and Radiation Dosimetry of Ga-68-DOTATOC and Ga-68-DOTATATE in Patients with Neuroendocrine Tumors
- 2013
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 54:10, s. 1755-1759
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Tidskriftsartikel (refereegranskat)abstract
- Ga-68-DOTATOC and Ga-68-DOTATATE are 2 radiolabeled somatostatin analogs for in vivo diagnosis of neuroendocrine tumors with PET. The aim of the present work was to measure their comparative biodistribution and radiation dosimetry. Methods: Ten patients diagnosed with neuroendocrine tumors were included. Each patient underwent a 45-min dynamic and 3 whole-body PET/CT scans at 1, 2, and 3 h after injection of each tracer on consecutive days. Absorbed doses were calculated using OLINDA/EXM 1.1. Results: Data from 9 patients could be included in the analysis. Of the major organs, the highest uptake at 1, 2, and 3 h after injection was observed in the spleen, followed by kidneys and liver. For both tracers, the highest absorbed organ doses were seen in the spleen and urinary bladder wall, followed by kidney, adrenals, and liver. The absorbed doses to the liver and gallbladder wall were slightly but significantly higher for Ga-68-DOTATATE. The total effective dose was 0.021 +/- 0.003 mSv/MBq for both tracers. Conclusion: The effective dose for a typical 100-MBq administration of Ga-68-DOTATATE and Ga-68-DOTATOC is 2.1 mSv for both tracers. Therefore, from a radiation dosimetry point of view, there is no preference for either tracer for PET/CT evaluation of somatostatin receptor-expressing tumors.
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| 7. |
- Sandström, Mattias, et al.
(författare)
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Individualized dosimetry of kidney and bone marrow in patients undergoing 177Lu-DOTA-octreotate treatment
- 2013
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 54:1, s. 33-41
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Tidskriftsartikel (refereegranskat)abstract
- The organs at risk in radionuclide therapy with 177Lu-octreotate are the bone marrow and the kidneys. The primary aim of this study was to develop an individualized dosimetry protocol for the bone marrow. The secondary aim was to identify those patients, undergoing fractionated therapy with 7.4 GBq/cycle, who first reached an accumulated dose of either 2 Gy to the bone marrow or 23 Gy to the kidneys. Methods: Two hundred patients with metastatic neuroendocrine tumors with high somatostatin receptor expression were included. After the administration of 7.4 GBq of 177Lu-octreotate, blood samples were drawn 6 times within the first 24 h. In 50 patients, additional blood samples were obtained at 96 and 168 h. Moreover, urine was collected from 30 patients during the first 24 h. Planar whole-body and SPECT/CT images over the abdomen were acquired at 24, 96, and 168 h after the infusion. Calculation of the absorbed radiation dose to the bone marrow was based on blood and urinary activity curves combined with organ-based analysis of the whole-body images. The absorbed dose to the kidney was calculated from the pharmacokinetic data obtained from SPECT/CT. Results: For a single cycle of 7.4 GBq, the absorbed dose to the bone marrow and the kidney ranged from 0.05 to 0.4 Gy and from 2 to 10 Gy, respectively. In 197 of 200 patients, the kidneys accumulated an absorbed dose of 23 Gy before the bone marrow reached 2 Gy. Between 2 and 10 cycles of 177Lu-octreotate could be administered before the upper dose limit for the individual patient was reached. Conclusion: A method based on repeated whole-body imaging in combination with blood and urinary activity data over time was developed to determine the absorbed dose to the bone marrow. The dose-limiting organ was the kidney in 197 of 200 patients. In 50% of the patients, more than 4 cycles of 7.4 GBq of 177Lu-octreotate could be administered, whereas 20% of the subjects were treated with fewer than 4 cycles. Individualized absorbed dose calculation is essential to optimize the therapy.
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| 8. |
- Velikyan, Irina, et al.
(författare)
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Quantitative and Qualitative Intrapatient Comparison of 68Ga-DOTATOC and 68Ga-DOTATATE : Net Uptake Rate for Accurate Quantification.
- 2014
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 55:2, s. 204-10
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Tidskriftsartikel (refereegranskat)abstract
- UNLABELLED: Quantitative imaging and dosimetry are crucial for individualized treatment during peptide receptor radionuclide therapy (PRRT). (177)Lu-DOTATATE and (68)Ga-DOTATOC/(68)Ga-DOTATATE are used, respectively, for PRRT and PET examinations targeting somatostatin receptors (SSTRs) in patients affected by neuroendocrine tumors. The aim of the study was to quantitatively and qualitatively compare the performance of (68)Ga-DOTATOC and (68)Ga-DOTATATE in the context of subsequent PRRT with (177)Lu-DOTATATE under standardized conditions in the same patient as well as to investigate the sufficiency of standardized uptake value (SUV) for estimation of SSTR expression.METHODS: Ten patients with metastatic neuroendocrine tumors underwent one 45-min dynamic and 3 whole-body PET/CT examinations at 1, 2, and 3 h after injection with both tracers. The number of detected lesions, SUVs in lesions and normal tissue, total functional tumor volume, and SSTR volume (functional tumor volume multiplied by mean SUV) were investigated for each time point. Net uptake rate (Ki) was calculated according to the Patlak method for 3 tumors per patient.RESULTS: There were no significant differences in lesion count, lesion SUV, Ki, functional tumor volume, or SSTR volume between (68)Ga-DOTATOC and (68)Ga-DOTATATE at any time point. The detection rate was similar, although with differences for single lesions in occasional patients. For healthy organs, marginally higher uptake of (68)Ga-DOTATATE was observed in kidneys, bone marrow, and liver at 1 h. (68)Ga-DOTATOC uptake was higher in mediastinal blood pool at the 1-h time point (P = 0.018). The tumor-to-liver ratio was marginally higher for (68)Ga-DOTATOC at the 3-h time point (P = 0.037). Blood clearance was fast and similar for both tracers. SUV did not correlate with Ki linearly and achieved saturation for a Ki of greater than 0.2 mL/cm(3)/min, corresponding to an SUV of more than 25.CONCLUSION: (68)Ga-DOTATOC and (68)Ga-DOTATATE are suited equally well for staging and patient selection for PRRT with (177)Lu-DOTATATE. However, the slight difference in the healthy organ distribution and excretion may render (68)Ga-DOTATATE preferable. SUV did not correlate linearly with Ki and thus may not reflect the SSTR density accurately at its higher values, whereas Ki might be the outcome measure of choice for quantification of SSTR density and assessment of treatment outcome.
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