| 1. |
|
|
| 2. |
- Hallqvist, Andreas, 1973, et al.
(författare)
-
Intraperitoneal alpha-Emitting Radioimmunotherapy with At-211 in Relapsed Ovarian Cancer: Long-Term Follow-up with Individual Absorbed Dose Estimations
- 2019
-
Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 2159-662X. ; 60:8, s. 1073-1079
-
Tidskriftsartikel (refereegranskat)abstract
- Eliminating microscopic residual disease with alpha-particle radiation is theoretically appealing. After extensive preclinical work with alpha-particle-emitting At-211, we performed a phase I trial with intraperitoneal alpha-particle therapy in epithelial ovarian cancer using At-211 conjugated to MX35, the antigen-binding fragments-F(ab')(2)-of a mouse monoclonal antibody. We now present clinical outcome data and toxicity in a long-term follow-up with individual absorbed dose estimations. Methods: Twelve patients with relapsed epithelial ovarian cancer, achieving a second complete or nearly complete response with chemotherapy, received intraperitoneal treatment with escalating (20-215 MBq/L) activity concentrations of At-211-MX35 F(ab')(2). Results: The activity concentration was escalated to 215 MBq/L without any dose-limiting toxicities. Most toxicities were low-grade and likely related to the treatment procedure, not clearly linked to the alpha-particle irradiation, with no observed hematologic toxicity. One grade 3 fatigue and 1 grade 4 intestinal perforation during catheter implantation were observed. Four patients had a survival of more than 6 y, one of whom did not relapse. At progression, chemotherapy was given without signs of reduced tolerability. Overall median survival was 35 mo, with a 1-, 2-, 5-, and 10-y survival of 100%, 83%, 50%, and 25%, respectively. Calculations of the absorbed doses showed that a lower specific activity is associated with a lower single-cell dose, whereas a high specific activity may result in a lower central dose in microtumors. Individual differences in absorbed dose to possible microtumors were due to variations in administered activity and the specific activity. Conclusion: No apparent signs of radiation-induced toxicity or decreased tolerance to relapse therapy were observed. The dosimetric calculations show that further optimization is advisable to increase the efficacy and reduce possible long-term toxicity.
|
|
| 3. |
- Albertsson, Per, 1964, et al.
(författare)
-
Astatine-211 based radionuclide therapy: Current clinical trial landscape
- 2023
-
Ingår i: Frontiers in Medicine. - : Frontiers Media SA. - 2296-858X. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Astatine-211 (At-211) has physical properties that make it one of the top candidates for use as a radiation source for alpha particle-based radionuclide therapy, also referred to as targeted alpha therapy (TAT). Here, we summarize the main results of the completed clinical trials, further describe ongoing trials, and discuss future prospects.
|
|
| 4. |
- Aneheim, Emma, 1982, et al.
(författare)
-
Automated astatination of biomolecules--a stepping stone towards multicenter clinical trials.
- 2015
-
Ingår i: Scientific reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 5
-
Tidskriftsartikel (refereegranskat)abstract
- To facilitate multicentre clinical studies on targeted alpha therapy, it is necessary to develop an automated, on-site procedure for conjugating rare, short-lived, alpha-emitting radionuclides to biomolecules. Astatine-211 is one of the few alpha-emitting nuclides with appropriate chemical and physical properties for use in targeted therapies for cancer. Due to the very short range of the emitted α-particles, this therapy is particularly suited to treating occult, disseminated cancers. Astatine is not intrinsically tumour-specific; therefore, it requires an appropriate tumour-specific targeting vector, which can guide the radiation to the cancer cells. Consequently, an appropriate method is required for coupling the nuclide to the vector. To increase the availability of astatine-211 radiopharmaceuticals for targeted alpha therapy, their production should be automated. Here, we present a method that combines dry distillation of astatine-211 and a synthesis module for producing radiopharmaceuticals into a process platform. This platform will standardize production of astatinated radiopharmaceuticals, and hence, it will facilitate large clinical studies focused on this promising, but chemically challenging, alpha-emitting radionuclide. In this work, we describe the process platform, and we demonstrate the production of both astaine-211, for preclinical use, and astatine-211 labelled antibodies.
|
|
| 5. |
- Aneheim, Emma, 1982, et al.
(författare)
-
Synthesis and Evaluation of Astatinated N-[2-(Maleimido)ethyl]-3-(trimethylstannyl)benzamide Immunoconjugates
- 2016
-
Ingår i: Bioconjugate chemistry. - : American Chemical Society (ACS). - 1520-4812 .- 1043-1802. ; 27:3, s. 688-97
-
Tidskriftsartikel (refereegranskat)abstract
- Effective treatment of metastasis is a great challenge in the treatment of different types of cancers. Targeted alpha therapy utilizes the short tissue range (50-100 μm) of α particles, making the method suitable for treatment of disseminated occult cancers in the form of microtumors or even single cancer cells. A promising radioactive nuclide for this type of therapy is astatine-211. Astatine-211 attached to tumor-specific antibodies as carrier molecules is a system currently under investigation for use in targeted alpha therapy. In the common radiolabeling procedure, astatine is coupled to the antibody arbitrarily on lysine residues. By instead coupling astatine to disulfide bridges in the antibody structure, the immunoreactivity of the antibody conjugates could possibly be increased. Here, the disulfide-based conjugation was performed using a new coupling reagent, maleimidoethyl 3-(trimethylstannyl)benzamide (MSB), and evaluated for chemical stability in vitro. The immunoconjugates were subsequently astatinated, resulting in both high radiochemical yield and high specific activity. The MSB-conjugate was shown to be stable with a long shelf life prior to the astatination. In a comparison of the in vivo distribution of the new immunoconjugate with other tin-based immunoconjugates in tumor-bearing mice, the MSB conjugation method was found to be a viable option for successful astatine labeling of different monoclonal antibodies.
|
|
| 6. |
- Bäck, Tom, 1964, et al.
(författare)
-
Cure of Human Ovarian Carcinoma Solid Xenografts by Fractionated alpha-Radioimmunotherapy with At-211-MX35-F(ab')(2): Influence of Absorbed Tumor Dose and Effect on Long-Term Survival
- 2017
-
Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 2159-662X. ; 58:4, s. 598-604
-
Tidskriftsartikel (refereegranskat)abstract
- The goal of this study was to investigate whether targeted a-therapy can be used to successfully treat macrotumors, in addition to its established role for treating micrometastatic and minimal disease. We used an intravenous fractionated regimen of alpha-radioimmunotherapy in a subcutaneous tumor model in mice. We aimed to evaluate the absorbed dose levels required for tumor eradication and growth monitoring, as well as to evaluate long-term survival after treatment. Methods: Mice bearing subcutaneous tumors (50 mm(3), NIH:OVCAR-3) were injected repeatedly (1-3 intravenous injections 7-10 d apart, allowing bone marrow recovery) with At-211-MX35-F (ab')(2) at different activities (close to acute myelotoxicity). Mean absorbed doses to tumors and organs were estimated from bio-distribution data and summed for the fractions. Tumor growth was monitored for 100 d and survival for 1 y after treatment. Toxicity analysis included body weight, white blood cell count, and hematocrit. Results: Effects on tumor growth after fractionated alpha-radioimmunotherapy with 211At-MX35-F(ab')(2) was strong and dose-dependent. Complete remission (tumor-free fraction, 100%) was found for tumor doses of 12.4 and 16.4 Gy. The administered activities were high, and long-term toxicity effects (60 wk) were clear. Above 1 MBq, the median survival decreased linearly with injected activity, from 44 to 11 wk. Toxicity was also seen by reduced body weight. White blood cell count analysis after a-radioimmunotherapy indicated bone marrow recovery for the low-activity groups, whereas for high-activity groups the reduction was close to acute myelotoxicity. A decrease in hematocrit was seen at a late interval (34-59 wk after therapy). The main external indication of poor health was dehydration. Conclusion: Having observed complete eradication of solid tumor xenografts, we conclude that targeted alpha-therapy regimens may stretch beyond the realm of micrometastatic disease and be eradicative also for macrotumors. Our observations indicate that at least 10 Gy are required. This agrees well with the calculated tumor control probability. Considering a relative biological effectiveness of 5, this dose level seems reasonable. However, complete remission was achieved first at activity levels close to lethal and was accompanied by biologic effects that reduced long-term survival.
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
- Bäck, Tom, 1964, et al.
(författare)
-
Targeted alpha therapy with astatine-211-labeled anti-PSCA A11 minibody shows antitumor efficacy in prostate cancer xenografts and bone microtumors
- 2020
-
Ingår i: Ejnmmi Research. - : Springer Science and Business Media LLC. - 2191-219X. ; 10:1
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose Targeted alpha therapy (TAT) is a promising treatment for micrometastatic and minimal residual cancer. We evaluated systemic alpha-radioimmunotherapy (alpha-RIT) of metastatic castration-resistant prostate cancer (mCRPC) using the alpha-particle emitter At-211-labeled to the anti-PSCA A11 minibody. A11 is specific for prostate stem cell antigen (PSCA), a cell surface glycoprotein which is overexpressed in more than 90% of both localized prostate cancer and bone metastases. Methods PC3-PSCA cells were implanted subcutaneously (s.c.) and intratibially (i.t) in nude mice. Efficacy of alpha-RIT (two fractions-14-day interval) was studied on s.c. macrotumors (0, 1.5 and 1.9 MBq) and on i.t. microtumors (100-200 mu m; 0, 0.8 or 1.5 MBq) by tumor-volume measurements. The injected activities for therapies were estimated from separate biodistribution and myelotoxicity studies. Results Tumor targeting of At-211-A11 was efficient and the effect on s.c. macrotumors was strong and dose-dependent. At 6 weeks, the mean tumor volumes for the treated groups, compared with controls, were reduced by approximately 85%. The separate myelotoxicity study following one single fraction showed reduced white blood cells (WBC) for all treated groups on day 6 after treatment. For the 0.8 and 1.5 MBq, the WBC reductions were transient and followed by recovery at day 13. For 2.4 MBq, a clear toxicity was observed and the mice were sacrificed on day 7. In the long-term follow-up of the 0.8 and 1.5 MBq-groups, blood counts on day 252 were normal and no signs of radiotoxicity observed. Efficacy on i.t. microtumors was evaluated in two experiments. In experiment 1, the tumor-free fraction (TFF) was 95% for both treated groups and significantly different (p < 0.05) from the controls at a TFF of 66%). In experiment 2, the difference in TFF was smaller, 32% for the treated group versus 20% for the controls. However, the difference in microtumor volume in experiment 2 was highly significant, 0.010 +/- 0.003 mm(3) versus 3.79 +/- 1.24 mm(3) (treated versus controls, respectively), i.e., a 99.7% reduction (p < 0.001). The different outcome in experiment 1 and 2 is most likely due to differences in microtumor sizes at therapy, or higher tumor-take in experiment 2 (where more cells were implanted). Conclusion Evaluating fractionated alpha-RIT with At-211-labeled anti-PSCA A11 minibody, we found clear growth inhibition on both macrotumors and intratibial microtumors. For mice treated with multiple fractions, we also observed radiotoxicity manifested by progressive loss in body weight at 30 to 90 days after treatment. Our findings are conceptually promising for a systemic TAT of mCRPC and warrant further investigations of At-211-labeled PSCA-directed vectors. Such studies should include methods to improve the therapeutic window, e.g., by implementing a pretargeted regimen of alpha-RIT or by altering the size of the targeting vector.
|
|
| 10. |
|
|
| 11. |
|
|
| 12. |
- Chouin, Nicolas, et al.
(författare)
-
Ex Vivo Activity Quantification in Micrometastases at the Cellular Scale Using the α-Camera Technique.
- 2013
-
Ingår i: Journal of nuclear medicine : official publication, Society of Nuclear Medicine. - : Society of Nuclear Medicine. - 1535-5667. ; 54:8, s. 1347-1353
-
Tidskriftsartikel (refereegranskat)abstract
- Targeted α-therapy (TAT) appears to be an ideal therapeutic technique for eliminating malignant circulating, minimal residual, or micrometastatic cells. These types of malignancies are typically infraclinical, complicating the evaluation of potential treatments. This study presents a method of ex vivo activity quantification with an α-camera device, allowing measurement of the activity taken up by tumor cells in biologic structures a few tens of microns. METHODS: We examined micrometastases from a murine model of ovarian carcinoma after injection of a radioimmunoconjugate labeled with (211)At for TAT. At different time points, biologic samples were excised and cryosectioned. The activity level and the number of tumor cells were determined by combined information from 2 adjacent sections: one exposed to the α-camera and the other stained with hematoxylin and eosin. The time-activity curves for tumor cell clusters, comprising fewer than 10 cells, were derived for 2 different injected activities (6 and 1 MBq). RESULTS: High uptake and good retention of the radioimmunoconjugate were observed at the surface of tumor cells. Dosimetric calculations based on the measured time-integrated activity indicated that for an injected activity of 1 MBq, isolated tumor cells received at least 12 Gy. In larger micrometastases (≤100 μm in diameter), the activity uptake per cell was lower, possibly because of hindered penetration of radiolabeled antibodies; however, the mean absorbed dose delivered to tumor cells was above 30 Gy, due to cross-fire irradiation. CONCLUSION: Using the α-camera, we developed a method of ex vivo activity quantification at the cellular scale, which was further applied to characterize the behavior of a radiolabeled antibody administered in vivo against ovarian carcinoma. This study demonstrated a reliable measurement of activity. This method of activity quantification, based on experimentally measured data, is expected to improve the relevance of small-scale dosimetry studies and thus to accelerate the optimization of TAT.
|
|
| 13. |
|
|
| 14. |
- Dekempeneer, Y., et al.
(författare)
-
Labeling of Anti-HER2 Nanobodies with Astatine-211: Optimization and the Effect of Different Coupling Reagents on Their in Vivo Behavior
- 2019
-
Ingår i: Molecular Pharmaceutics. - : American Chemical Society (ACS). - 1543-8384 .- 1543-8392. ; 16:8, s. 3524-3533
-
Tidskriftsartikel (refereegranskat)abstract
- The use of nanobodies (Nbs) as vehicles in targeted alpha therapy (TAT) has gained great interest because of their excellent properties. They combine high in vivo affinity and specificity of binding with fast kinetics. This research investigates a novel targeted therapy that combines the alpha-particle emitter astatine-211 (At-211) and the anti-HER2 Nb 2Rs15d to selectively target HER2+ cancer cells. Two distinctive radiochemical methodologies are investigated using three different coupling reagents. The first method uses the coupling reagents, N-succinimidyl 4-(1,2-bis-tert-butoxycarbonyl)guanidinomethyl-3-(trimethylstannyl)benzo ate (Boc(2)-SGMTB) and N-succinimidyl-3-(trimethylstannyl)-benzoate (m-MeATE), which are both directed to amino groups on the Nb, resulting in random conjugation. The second method aims at obtaining a homogeneous tracer population, via a site-specific conjugation of the N-[2-(maleimido)ethyl]-3-(trimethylstannyl)benzamide (MSB) reagent onto the carboxyl-terminal cysteine of the Nb. The resulting radioconjugates are evaluated in vitro and in vivo. 2Rs15d is labeled with At-211 using Boc(2)-SGMTB, m-MeATE, and MSB. After astatination and purification, the binding specificity of the radioconjugates is validated on HER2+ cells, followed by an in vivo biodistribution assessment in SKOV-3 xenografted mice. alpha-camera imaging is performed to determine uptake and activity distribution in kidneys/tumors. 2Rs15d astatination resulted in a high radiochemical purity >95% for all radioconjugates. The biodistribution studies of all radioconjugates revealed comparable tumor uptake (higher than 8% ID/g at 1 h). [At-211]SAGMB-2Rs15d showed minor uptake in normal tissues. Only in the kidneys, a higher uptake was measured after 1 h, but decreased rapidly after 3 h. Astatinated Nbs consisting of m-MeATE or MSB reagents revealed elevated uptake in lungs and stomach, indicating the presence of released At-211. alpha-Camera imaging of tumors revealed a homogeneous activity distribution. The radioactivity in the kidneys was initially concentrated in the renal cortex, while after 3 h most radioactivity was measured in the medulla, confirming the fast washout into urine. Changing the reagents for Nb astatination resulted in different in vivo biodistribution profiles, while keeping the targeting moiety identical. Boc(2)-SGMTB is the preferred reagent for Nb astatination because of its high tumor uptake, its low background signals, and its fast renal excretion. We envision [At-211]SAGMB-2Rs15d to be a promising therapeutic agent for TAT and aim toward efficacy evaluation.
|
|
| 15. |
|
|
| 16. |
- Gustafsson-Lutz, Anna, 1981, et al.
(författare)
-
Therapeutic efficacy of alpha-radioimmunotherapy with different activity levels of the Bi-213-labeled monoclonal antibody MX35 in an ovarian cancer model
- 2017
-
Ingår i: EJNMMI Research. - : Springer Science and Business Media LLC. - 2191-219X. ; 7
-
Tidskriftsartikel (refereegranskat)abstract
- Background: The aim of this study was to compare the therapeutic efficacy of two different activity levels of the Bi-213-labeled monoclonal antibody MX35 in an ovarian cancer model. Sixty female BALB/c (nu/nu) mice were inoculated intraperitoneally with human ovarian cancer cells (OVCAR-3). Two weeks later, 40 mice were injected intraperitoneal (i.p.) with 1 ml of Bi-213-MX35, 3 MBq/mL (n = 20), or 9 MBq/mL (n = 20). An additional 20 mice received unlabeled MX35. Incidence of tumors and ascites was investigated 8 weeks after therapy. Body weight and white blood cell counts were monitored after treatment for possible signs of toxicity. Results: The tumor-free fraction of the animals treated with 3 MBq/mL of Bi-213-MX35 was 0.55, whereas that of animals treated with 9 MBq/mL of Bi-213-MX35 was 0.78. The control group treated with unlabeled MX35 had a tumor-free fraction of 0.15. No significant reduction in white blood cell counts or weight loss was observed. Conclusions: Tumor growth after i.p. treatment with Bi-213-MX35 was significantly reduced compared to treatment with unlabeled MX35. Treatment with 9 MBq/mL of Bi-213-MX35 resulted in higher tumor-free fraction compared with 3 MBq/mL of Bi-213-MX35, but this difference was not statistically significant. No signs of toxicity were observed in the treated animals.
|
|
| 17. |
- Hultborn, Ragnar, 1946, et al.
(författare)
-
Radiosensitivity: Gender and Order of Administration of G-CSF, An Experimental Study in Mice
- 2019
-
Ingår i: Radiation Research. - : Radiation Research Society. - 0033-7587. ; 191:4, s. 335-341
-
Tidskriftsartikel (refereegranskat)abstract
- To elucidate the potential influence of stimulating bone marrow before cell-cycle-dependent irradiation, we sought to determine overall survival in mice receiving total-body irradiation (TBI) when administered granulocyte stimulating factor (G-CSF) at different time points. Gender differences were also studied. C57/BL/6J mice, aged 9-14 weeks, received 8 Gy TBI in a perspex cage using a linear accelerator. In each of five different experiments, three groups were studied: 1. one control group receiving TBI only; 2. one group treated with filgrastim [500 mu g/kg subcutaneously/intraperitoneally (s.c./i.p.)] the day before TBI, followed by daily filgrastim injections postirradiation (1-5 days); and 3. one group treated with daily filgrastim injections only post-TBI (1-5 days). Each experimental group included male and female mice. Survival of the mice was monitored daily, and mice were euthanized when their condition deteriorated. A total of 293 mice were monitored for at least 37 days post-TBI. Control mice that received 8 Gy TBI showed a significant gender difference, with a median survival of 22 days in females and 17 days in males. Addition of G-CSF, irrespective of pre- or postirradiation, significantly improved survival, but in males the improvement was significantly better when G-CSF was not given before TBI. Improved survival in females was independent of the order of administration of G-CSF. Multiple filgrastim injections were more effective than a single injection, and s.c. administration was not better than i.p. In conclusion, these findings indicate that male mice are more sensitive to TBI than females. Filgrastim improved survival in both genders irrespective of whether given pre- orpostirradiation, but in males the improvement was significantly less if an injection was given before irradiation. These results suggest that, to prevent toxicity most effectively, G-CSF should not be given before cytotoxic therapy. While a completely different experimental model was used here, these results may also be extrapolated to indicate that endocrine cell-cycle suppression therapy should not be given before or during cytotoxic therapy of hormone-dependent tumors (e.g., breast and prostate cancer), thus a reduction in the efficacy of cell-cycle-dependent therapy can be prevented. (C) 2019 by Radiation Research Society
|
|
| 18. |
- Leidermark, Erik, 1981, et al.
(författare)
-
Estimating the risk for secondary cancer following targeted alpha therapy with astatine-211 intraperitoneal radioimmunotherapy.
- 2022
-
Ingår i: Journal of nuclear medicine : official publication, Society of Nuclear Medicine. - : Society of Nuclear Medicine. - 1535-5667. ; 64:1, s. 165-172
-
Tidskriftsartikel (refereegranskat)abstract
- Intraperitoneal 211At-based targeted alpha therapy (TAT) may hold most promise as an adjuvant therapy following surgery and chemotherapy in epithelial ovarian cancer to eradicate any remaining undetectable disease. This implies it will also be delivered to patients possibly already cured by the primary treatment. An estimate of long-term risks is therefore sought whether to justify the treatment. Methods: Baseline data for risk estimates of alpha-particle irradiation were collected from published studies on excess cancer induction and mortality for subjects exposed to either 224Ra treatments or Thorotrast contrast agent (25% ThO2 colloid, containing 232Th). Organ dosimetry for 224Ra and Thorotrast irradiation were taken from the literature. These organ-specific risks were then applied for our previously reported dosimetry for intraperitoneal (i.p.) 211At-TAT patients. Results: Risk could be estimated for 10 different organ or organ groups. The calculated excess relative risk per Gray (ERR/Gy) could be sorted into two groups. In the lower ERR/Gy group, up to approx. 5, were: Trachea, bronchus and lung 0.52 (CI 95% 0.21-0.82), Stomach 1.4 (CI 95% -5.0-7.9), Lymphoid and hematopoietic system 2.17 (CI 95% 1.7-2.7), Bone and articular cartilage 2.6 (CI 95% 2.0-3.3), Breast 3.45 (CI 95% -10-17) and Colon 4.5 (CI 95% -3.5-13). In the higher ERR/Gy group, ranging from approx. 10 to 15 were: Urinary bladder 10.1 (CI 95% 1.4-23), Liver 14.2 (CI 95% 13-16), Kidney 14.9 (CI 95% 3.9-26) and Lip, oral cavity and pharynx 15.20 (CI 95% 2.73-27.63). Applying a typical candidate patient (female, age 65 years) and correcting for reference population mortality rate, a total estimated excess mortality of an i.p. 211At-mAb treatment amounted to 1.13 per 100 treated. More than half of this excess originated from urinary bladder and kidney, 0.29 and 0.34 respectively. Depending on various adjustments in calculation and assumptions on competing risks excess mortality could range from 0.11 - 1.84 per 100 treated. Conclusion: Published epidemiological data on life-long detriment following alpha-particle irradiation and its dosimetry allowed calculations to estimate the risk for secondary cancer following 211At-based i.p. TAT. Measures to reduce dose to the urinary organs may further decrease the estimated relative low risk for secondary cancer from 211At-mAb based i.p. TAT.
|
|
| 19. |
- Lindegren, Sture, 1960, et al.
(författare)
-
Astatine-211: The Chemistry Infrastructure.
- 2019
-
Ingår i: Journal of Medical Imaging and Radiation Sciences. - 1939-8654.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
|
|
| 20. |
- Lindegren, Sture, 1960, et al.
(författare)
-
Binding Affinity, Specificity and Comparative Biodistribution of the Parental Murine Monoclonal Antibody MX35 (Anti-NaPi2b) and Its Humanized Version Rebmab200.
- 2015
-
Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 10:5
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this preclinical study was to evaluate the characteristics of the monoclonal antibody Rebmab200, which is a humanized version of the ovarian-specific murine antibody MX35. This investigation contributes to the foundation for future clinical α-radioimmunotherapy of minimal residual ovarian cancer with 211At-Rebmab200. Here, the biodistribution of 211At-Rebmab200 was evaluated, as was the utility of 99mTc-Rebmab200 for bioimaging. Rebmab200 was directly compared with its murine counterpart MX35 in terms of its in-vitro capacity for binding the immobilized NaPi2B epitope and live cells; we also assessed its biodistribution in nude mice carrying subcutaneous OVCAR-3 tumors. Tumor antigen and cell binding were similar between Rebmab200 and murine MX35, as was biodistribution, including normal tissue uptake and in-vivo tumor binding. We also demonstrated that 99mTc-Rebmab200 can be used for single-photon emission computed tomography of subcutaneous ovarian carcinomas in tumor-bearing mice. Taken together, our data support the further development of Rebmab200 for radioimmunotherapy and diagnostics.
|
|
| 21. |
- Lindegren, Sture, 1960, et al.
(författare)
-
Realizing Clinical Trials with Astatine-211: The Chemistry Infrastructure
- 2020
-
Ingår i: Cancer Biotherapy and Radiopharmaceuticals. - : Mary Ann Liebert Inc. - 1084-9785 .- 1557-8852. ; 35:6, s. 425-436
-
Tidskriftsartikel (refereegranskat)abstract
- Despite the consensus around the clinical potential of the alpha-emitting radionuclide astatine-211 (At-211), there are only a limited number of research facilities that work with this nuclide. There are three main reasons for this: (1) Scarce availability of the nuclide. Despite a relatively large number of globally existing cyclotrons capable of producing(211)At, few cyclotron facilities produce the nuclide on a regular basis. (2) Lack of a chemical infrastructure, that is, isolation of(211)At from irradiated targets and the subsequent synthesis of an astatinated product. At present, the research groups that work with(211)At depend on custom systems for recovering(211)At from the irradiated targets. Setting up and implementing such custom units require long lead times to provide a proper working system. (3) The chemistry of(211)At. Compared with radiometals there are no well-established and generally accepted synthesis methods for forming sufficiently stable bonds between(211)At and the tumor-specific vector to allow for systemic applications. Herein we present an overview of the infrastructure of producing(211)At radiopharmaceuticals, from target to radiolabeled product including chemical strategies to overcome hurdles for advancement into clinical trials with(211)At.
|
|
| 22. |
- Palm, Stig, 1964, et al.
(författare)
-
Biokinetic modeling and dosimetry for optimizing intraperitoneal radioimmunotherapy of ovarian cancer microtumors.
- 2016
-
Ingår i: Journal of nuclear medicine : official publication, Society of Nuclear Medicine. - : Society of Nuclear Medicine. - 1535-5667. ; 57:4, s. 594-600
-
Tidskriftsartikel (refereegranskat)abstract
- A biokinetic model was constructed to evaluate and optimize various intraperitoneal (i.p.) radioimmunotherapies for micrometastatic tumors. The model was used to calculate the absorbed dose to both anticipated microtumors and critical healthy organs and demonstrates how i.p. targeted radiotherapy can be optimized to achieve a maximum ratio between them.
|
|
| 23. |
|
|
| 24. |
- Palm, Stig, 1964, et al.
(författare)
-
Evaluation of therapeutic efficacy of 211At-labeled farletuzumab in an intraperitoneal mouse model of disseminated ovarian cancer
- 2021
-
Ingår i: Translational Oncology. - : Elsevier BV. - 1936-5233. ; 14:1
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction: Antibodies labeled with alpha-emitter astatine-211 have previously shown effective in intraperitoneal (i.p.) treatments of ovarian cancer. In the present work we explore the use of investigational farletuzumab, aimed at the folate receptor alpha. The aim was to evaluate the biodistribution and therapeutic effect of 211At-farletuzumab in in-vitro and in-vivo experiments and, using models for radiation dosimetry, to translate the findings to expected clinical result. The activity concentration used for therapy in mice (170 kBq/mL) was chosen to be in agreement with an activity concentration that is anticipated to be clinically relevant in patients (200 MBq/L). Methods: For biodistribution, using intravenous injections and mice carrying subcutaneous (s.c.) tumors, the animals were administered either 211At-farletuzumab (n = 16); or with a combination of 125I-farletuzumab and 211At-MX35 (n = 12). At 1, 3, 10 and 22 h, mice were euthanized and s.c.-tumors and organs weighted and measured for radioactivity. To evaluate therapeutic efficacy, mice were inoculated i.p. with 2 × 106 NIH:OVCAR-3 cells. Twelve days later, the treatments were initiated by i.p.-administration. Specific treatment was given by 211At-labeled farletuzumab (group A; n = 22, 170 kBq/mL) which is specific for OVCAR-3 cells. Control treatments were given by either 211At-labeled rituximab which is unspecific for OVCAR-3 (group B; n = 22, 170 kBq/mL), non-radiolabeled farletuzumab (group C; n = 11) or PBS only (group D; n = 8). Results: The biodistribution of 211At-farletuzumab was similar to that with 125I as radiolabel, and also to that of 211At-labeled MX35 antibody. The tumor-free fraction (TFF) of the three control groups were all low (PBS 12%, unlabeled specific farletuzumab 9% and unspecific 211At-rituximab 14%). TFF following treatment with 211At-farletuzumab was 91%. Conclusion: The current investigation of intraperitoneal therapy with 211At-farletuzumab, delivered at clinically relevant 211At-mAb radioactivity concentrations and specific activities, showed a 6 to 10-fold increase (treated versus controls) in antitumor efficacy. This observation warrants further clinical testing. © 2020 The Authors
|
|
| 25. |
- Palm, Stig, 1964, et al.
(författare)
-
Model of Intraperitoneal Targeted α-Particle Therapy Shows That Posttherapy Cold-Antibody Boost Enhances Microtumor Radiation Dose and Treatable Tumor Sizes.
- 2018
-
Ingår i: Journal of nuclear medicine : official publication, Society of Nuclear Medicine. - : Society of Nuclear Medicine. - 1535-5667. ; 59:4, s. 646-651
-
Tidskriftsartikel (refereegranskat)abstract
- Intraperitoneally administered radiolabeled monoclonal antibodies (mAbs) have been tested in several clinical trials, often with promising results, but have never proven curative. Methods: We have previously presented simulations of clinically relevant amounts of intraperitoneal 90Y-mAbs for treatment of minimal disease and shown that such treatments are unlikely to eradicate microtumors. Our previous model simulated the kinetics of intraperitoneally infused radiolabeled mAbs in humans and showed the benefit of instead using α-emitters such as 211At. In the current work, we introduce penetration of mAbs into microtumors with radii of up to 400 μm. Calculations were performed using dynamic simulation software. To determine the radiation dose distribution in nonvascularized microtumors of various sizes after intraperitoneal 211At-radioimmunotherapy, we used an in-house-developed Monte Carlo program for microdosimetry. Our aim was to find methods that optimize the therapy for as wide a tumor size range as possible. Results: Our results show that high-specific-activity radiolabeled mAbs that are bound to a tumor surface will penetrate slowly compared with the half-lives of 211At and shorter-lived radionuclides. The inner-core cells of tumors with radii exceeding 100 μm may therefore not be sufficiently irradiated. For lower specific activities, the penetration rate and dose distribution will be more favorable for such tumors, but the dose to smaller microtumors and single cells will be low. Conclusion: Our calculations show that the addition of a boost with unlabeled mAb 1-5 h after therapy results in sufficient absorbed doses both to single cells and throughout microtumors up to approximately 300 μm in radius. This finding should also hold for other high-affinity mAbs and short-lived α-emitters.
|
|
| 26. |
|
|
| 27. |
- Albertsson, Per, 1964, et al.
(författare)
-
Positron emission tomography and computed tomographic (PET/CT) imaging for radiation therapy planning in anal cancer: A systematic review and meta-analysis
- 2018
-
Ingår i: Critical reviews in oncology/hematology. - : Elsevier BV. - 1040-8428. ; 126, s. 6-12
-
Forskningsöversikt (refereegranskat)abstract
- To improve the accuracy of chemoradiation therapy in anal cancer patients PET/CT is frequently used in the planning of radiation therapy. A systematic review was performed to assess impact on survival, quality of life, symptom score, change in target definition and treatment intention. Systematic literature searches were conducted in Medline, EMBASE, the Cochrane Library, and Centre for Reviews and Dissemination. Ten cross-sectional studies were identified. No data were available on survival or quality of life. The summary estimate of the proportion of patients in which PET/CT had an impact on the target definition, was 23% (95% CI 16;33). The corresponding summary estimate of a change in treatment intent from curative to palliative was 3% (95% CI 2;6). Almost one in four patients had a change in target definition, which supports the use of PET/CT in radiation therapy planning, but the consequence regarding survival and quality of life is still uncertain.
|
|
| 28. |
- Andersson, Håkan, 1944, et al.
(författare)
-
Comparison of the therapeutic efficacy of 211At- and 131I-labelled monoclonal antibody MOv18 in nude mice with intraperitoneal growth of human ovarian cancer.
- 2001
-
Ingår i: Anticancer research. - 0250-7005. ; 21:1A, s. 409-12
-
Tidskriftsartikel (refereegranskat)abstract
- The purpose of the present study was to compare the therapeutic efficacy of the alpha-emitter Astatine-211 with the beta-emitter Iodine-131 bound to the specific monoclonal antibody MOv18. The measurements were performed in an ovarian cancer cell line (NIH:OVCAR 3) growing intraperitoneally in nude mice. Two weeks after the intraperitoneal inoculation of 1 x 10(7) cells of the human ovarian cancer cell line NIH:OVCAR-3 twenty mice were treated intraperitoneally with the specific monoclonal antibody MOv-18 labelled with either 211At (310-400 kBq) or 131I (5100-6200 kBq). The pharmacokinetics and biodistribution of labelled antibody in tumour-free animals were studied and the resulting bone marrow dose was estimated. When the mice were treated with 211At-labelled antibody 9 out of 10 mice were free of macro- and microscopic tumour compared to 3 out of 10 when Iodine-131 was used. The equivalent dose to the bone marrow was 2.4-3.1 Sv from 211At- and 3.4-4.1 Sv from 131I-irradiation. The therapeutic efficacy of 211At-labelled specific antibody is very good and, at approximately equivalent bone marrow doses, better than that of 131I.
|
|
| 29. |
- Andersson, Håkan, 1944, et al.
(författare)
-
Intraperitoneal alpha-particle radioimmunotherapy of ovarian cancer patients: pharmacokinetics and dosimetry of (211)At-MX35 F(ab')2--a phase I study.
- 2009
-
Ingår i: Journal of nuclear medicine : official publication, Society of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505. ; 50:7, s. 1153-60
-
Tidskriftsartikel (refereegranskat)abstract
- The alpha-emitter (211)At labeled to a monoclonal antibody has proven safe and effective in treating microscopic ovarian cancer in the abdominal cavity of mice. Women in complete clinical remission after second-line chemotherapy for recurrent ovarian carcinoma were enrolled in a phase I study. The aim was to determine the pharmacokinetics for assessing absorbed dose to normal tissues and investigating toxicity. METHODS: Nine patients underwent laparoscopy 2-5 d before the therapy; a peritoneal catheter was inserted, and the abdominal cavity was inspected to exclude the presence of macroscopic tumor growth or major adhesions. (211)At was labeled to MX35 F(ab')(2) using the reagent N-succinimidyl-3-(trimethylstannyl)-benzoate. Patients were infused with (211)At-MX35 F(ab')(2) (22.4-101 MBq/L) in dialysis solution via the peritoneal catheter. gamma-Camera scans were acquired on 3-5 occasions after infusion, and a SPECT scan was acquired at 6 h. Samples of blood, urine, and peritoneal fluid were collected at 1-48 h. Hematology and renal and thyroid function were followed for a median of 23 mo. RESULTS: Pharmacokinetics and dosimetric results were related to the initial activity concentration (IC) of the infused solution. The decay-corrected activity concentration decreased with time in the peritoneal fluid to 50% IC at 24 h, increased in serum to 6% IC at 45 h, and increased in the thyroid to 127% +/- 63% IC at 20 h without blocking and less than 20% IC with blocking. No other organ uptakes could be detected. The cumulative urinary excretion was 40 kBq/(MBq/L) at 24 h. The estimated absorbed dose to the peritoneum was 15.6 +/- 1.0 mGy/(MBq/L), to red bone marrow it was 0.14 +/- 0.04 mGy/(MBq/L), to the urinary bladder wall it was 0.77 +/- 0.19 mGy/(MBq/L), to the unblocked thyroid it was 24.7 +/- 11.1 mGy/(MBq/L), and to the blocked thyroid it was 1.4 +/- 1.6 mGy/(MBq/L) (mean +/- SD). No adverse effects were observed either subjectively or in laboratory parameters. CONCLUSION: This study indicates that by intraperitoneal administration of (211)At-MX35 F(ab')(2) it is possible to achieve therapeutic absorbed doses in microscopic tumor clusters without significant toxicity.
|
|
| 30. |
- Aneheim, Emma, 1982, et al.
(författare)
-
Towards elucidating the radiochemistry of astatine - Behavior in chloroform
- 2019
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Targeted alpha therapy of disseminated cancer is an emerging technique where astatine-211 is one of the most promising candidate nuclides. Although astatine has been known for over 70 years, its chemistry is still largely unexplored, mainly due to the lack of stable or long-lived isotopes. However, substantial amounts of astatine-211 can be produced in cyclotrons by the bombardment of natural bismuth. The astatine can be recovered from the resulting irradiated target material through either wet extraction or dry-distillation. Chloroform has become an important intermediate solvent for the recovery of astatine after production, especially following dry distillation. In this work, the radiochemistry of astatine in chloroform was investigated using evaporation, solvent extraction, chromatographic methods and molecular modeling. The extraction of astatine in chloroform led to the formation of multiple astatine species, allowing for evaporation of the solvent to dryness without any loss of activity. Radiolysis products of chloroform were shown to play an important role in the speciation of astatine forming both reactive and kinetically stable compounds. It was hypothesized that reactions with chlorine, as well as trichloromethyl hydroperoxide, forming polar astatine compounds are important reactions under the current experimental conditions.
|
|
| 31. |
- Bäck, Tom, 1964, et al.
(författare)
-
211At radioimmunotherapy of subcutaneous human ovarian cancer xenografts: evaluation of relative biologic effectiveness of an alpha-emitter in vivo
- 2005
-
Ingår i: J Nucl Med. - 0161-5505. ; 46:12, s. 2061-7
-
Tidskriftsartikel (refereegranskat)abstract
- The use of alpha-particle emitters in radioimmunotherapy (RIT) appears to be promising. We previously obtained convincing results in the treatment of microscopic intraperitoneal ovarian cancer in nude mice by using the alpha-emitter 211At. This study was performed to evaluate the relative biological effectiveness (RBE) of 211At compared with that of 60Co gamma-irradiation in an RIT model. Our endpoint was growth inhibition (GI) of subcutaneous xenografts. METHODS: GI after irradiation was studied with subcutaneous xenografts of the human ovarian cancer cell line NIH:OVCAR-3 implanted in nude mice. The animals received an intravenous injection of 211At-labeled monoclonal antibody MX35 F(ab')2 at different levels of radioactivity (0.33, 0.65, and 0.90 MBq). Control mice received unlabeled MX35 F(ab')2 only. To calculate the mean absorbed dose to tumor, a separate biodistribution study established the uptake of 211At in tumors and organs at different times after injection. External irradiation of the tumors was performed with 60Co. Tumor growth was monitored, and the normalized tumor volume (NTV) was calculated for each tumor. GI was defined by dividing the NTV values by the fitted NTV curve obtained from the corresponding control mice. To compare the biologic effects of the 2 radiation qualities, the mean value for GI (from day 8 to day 23) was plotted for each tumor as a function of its corresponding absorbed dose. From exponential fits of these curves, the doses required for a GI of 0.37 (D37) were derived, and the RBE of 211At was calculated. RESULTS: The biodistribution study showed the uptake of the immunoconjugate by the tumor (amount of injected radioactivity per gram) to be 14% after 7 h. At 40 h, the ratio of uptake in tumors to uptake in blood reached a maximum value of 6.2. The administered activities of 211At corresponded to doses absorbed by tumors of 1.35, 2.65, and 3.70 Gy. The value (mean+/-SEM) for D37 was 1.59+/-0.08 Gy. Tumor growth after 60Co external irradiation showed a value for D37 of 7.65+/-1.0 Gy. The corresponding RBE of 211At irradiation was 4.8+/-0.7. CONCLUSION: Using a tumor GI model in nude mice, we were able to derive an RBE of alpha-particle RIT with 211At. The RBE was found to be 4.8+/-0.7.
|
|
| 32. |
- Bäck, Tom, 1964, et al.
(författare)
-
A Novel Method for Real-Time Quantification of Radioligand Binding to Living Tumor Cells In Vitro
- 2024
-
Ingår i: CANCER BIOTHERAPY AND RADIOPHARMACEUTICALS. - 1084-9785 .- 1557-8852. ; 39:1, s. 75-81
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Real-time quantification of radioligand binding to cells under in vivo-like conditions improves evaluation of clinical potential.Materials and Methods: SKOV-3 tumor cells were grown in a monolayer on a thin glass plate placed in a sealable shallow chamber with a continuous flow of 125I-trastuzumab solution. The time-dependent cell binding was measured using a NaI detector, and the binding parameters were derived by computational analysis.Results: The detection efficiency of 125I was 65 cps/kBq for radioligand bound to the cells. Experiments were analyzed to find the values of kon and koff. The resulting kon was 3.2-7.9 x 10(4) M-1 s(-1) and koff was 0.11-4.2 x 10(-5) s(-1).Conclusions: Radioligands can be rapidly evaluated by binding to living cells for selection and optimization of radioconjugates for diagnostic and therapeutic purposes.
|
|
| 33. |
|
|
| 34. |
- Cederkrantz, Elin, et al.
(författare)
-
Absorbed Doses and Risk Estimates of (211)At-MX35 F(ab')2 in Intraperitoneal Therapy of Ovarian Cancer Patients.
- 2015
-
Ingår i: International journal of radiation oncology, biology, physics. - : Elsevier BV. - 1879-355X .- 0360-3016. ; 93:3, s. 569-76
-
Tidskriftsartikel (refereegranskat)abstract
- Ovarian cancer is often diagnosed at an advanced stage with dissemination in the peritoneal cavity. Most patients achieve clinical remission after surgery and chemotherapy, but approximately 70% eventually experience recurrence, usually in the peritoneal cavity. To prevent recurrence, intraperitoneal (i.p.) targeted α therapy has been proposed as an adjuvant treatment for minimal residual disease after successful primary treatment. In the present study, we calculated absorbed and relative biological effect (RBE)-weighted (equivalent) doses in relevant normal tissues and estimated the effective dose associated with i.p. administration of (211)At-MX35F(ab')2.
|
|
| 35. |
|
|
| 36. |
- Elgqvist, Jörgen, 1963, et al.
(författare)
-
Administered activity and metastatic cure probability during radioimmunotherapy of ovarian cancer in nude mice with 211At-MX35 F(ab')2.
- 2006
-
Ingår i: International journal of radiation oncology, biology, physics. - : Elsevier BV. - 1879-355X .- 0360-3016. ; 66:4, s. 1228-37
-
Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To elucidate the therapeutic efficacy of alpha-radioimmunotherapy of ovarian cancer in mice. This study: (i) estimated the minimum required activity (MRA), giving a reasonable high therapeutic efficacy; and (ii) calculated the specific energy to tumor cell nuclei and the metastatic cure probability (MCP) using various assumptions regarding monoclonal-antibody (mAb) distribution in measured tumors. The study was performed using the alpha-particle emitter Astatine-211 (211At) labeled to the mAb MX35 F(ab')2. METHODS AND MATERIALS: Animals were inoculated intraperitoneally with approximately 1 x 10(7) cells of the cell line NIH:OVCAR-3. Four weeks later animals were treated with 25, 50, 100, or 200 kBq 211At-MX35 F(ab')2 (n = 74). Another group of animals was treated with a nonspecific mAb: 100 kBq 211At-Rituximab F(ab')2 (n = 18). Eight weeks after treatment the animals were sacrificed and presence of macro- and microscopic tumors and ascites was determined. An MCP model was developed and compared with the experimentally determined tumor-free fraction (TFF). RESULTS: When treatment was given 4 weeks after cell inoculation, the TFFs were 25%, 22%, 50%, and 61% after treatment with 25, 50, 100, or 200 kBq (211)At-MX35 F(ab')2, respectively, the specific energy to irradiated cell nuclei varying between approximately 2 and approximately 400 Gy. CONCLUSION: As a significant increase in the therapeutic efficacy was observed between the activity levels of 50 and 100 kBq (TFF increase from 22% to 50%), the conclusion was that the MRA is approximately 100 kBq (211)At-MX35 F(ab')2. MCP was most consistent with the TFF when assuming a diffusion depth of 30 mum of the mAbs in the tumors.
|
|
| 37. |
- Elgqvist, Jörgen, 1963, et al.
(författare)
-
Alpha-radioimmunotherapy of intraperitoneally growing OVCAR-3 tumors of variable dimensions: Outcome related to measured tumor size and mean absorbed dose.
- 2006
-
Ingår i: Journal of nuclear medicine : official publication, Society of Nuclear Medicine. - 0161-5505 .- 2159-662X. ; 47:8, s. 1342-50
-
Tidskriftsartikel (refereegranskat)abstract
- The purpose of this work was to (a) investigate the efficacy of radioimmunotherapy using 211At-MX35 F(ab')2 or 211At-Rituximab F(ab')2 (nonspecific antibody) against differently advanced ovarian cancer in mice; (b) image the tumor growth on the peritoneum; and (c) calculate the specific energy and mean absorbed dose to tumors and critical organs. METHODS: Two experiments with 5-wk-old nude mice (n = 100 + 93), intraperitoneally inoculated with approximately 1 x 10(7) NIH:OVCAR-3 cells, were done. At either 1, 3, 4, 5, or 7 wk after inoculation animals were intraperitoneally treated with approximately 400 kBq 211At-MX35 F(ab')2 (n = 50 + 45), approximately 400 kBq 211At-Rituximab F(ab')2 (n = 25 + 24), or unlabeled Rituximab F(ab')2 (n = 25 + 24). At the time of treatment 29 animals were sacrificed and biopsies were taken for determination of tumor sizes using scanning electron microscopy (SEM). Eight weeks after each treatment the animals were sacrificed and the presence of macro- and microscopic tumors and ascites was determined. The specific energy and mean absorbed dose to tumors were calculated. The activity concentration was measured in critical organs and abdominal fluid. RESULTS: When given treatment 1, 3, 4, 5, or 7 wk after cell inoculation the tumor-free fraction (TFF) was 95%, 68%, 58%, 47%, 26%, and 100%, 80%, 20%, 20%, and 0% when treated with 211At-MX35 F(ab')2 or 211At-Rituximab F(ab')2, respectively. The SEM images revealed maximum tumor radius of approximately 30 mum 1 wk after cell inoculation, increasing to approximately 340 mum at 7 wk. Specific energy to cell nuclei varied between 0 and approximately 540 Gy, depending on assumptions regarding activity distribution and tumor size. The mean absorbed dose to thyroid, kidneys, and bone marrow was approximately 35, approximately 4, and approximately 0.3 Gy, respectively. CONCLUSION: Treatment with 211At-MX35 F(ab')2 or 211At-Rituximab F(ab')2 resulted in a TFF of 95%-100% when the tumor radius was < or =30 microm. The TFF was decreased (TFF < or = 20%) for 211At-Rituximab F(ab')2 when the tumor radius exceeded the range of the alpha-particles. The specific antibody gave for these tumor sizes a significantly better TFF, explained by a high mean absorbed dose (>22 Gy) from the activity bound to the tumor surface and probably some contribution from penetrating activity.
|
|
| 38. |
- Elgqvist, Jörgen, 1963, et al.
(författare)
-
Fractionated radioimmunotherapy of intraperitoneally growing ovarian cancer in nude mice with 211At-MX35 F(ab')2: therapeutic efficacy and myelotoxicity
- 2006
-
Ingår i: Nucl Med Biol. - : Elsevier BV. - 0969-8051. ; 33:8, s. 1065-72
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The aim of this study was to investigate the therapeutic efficacy and myelotoxicity during fractionated radioimmunotherapy of ovarian cancer in mice. The study was performed using the monoclonal antibody MX35 F(ab')(2) labeled with the alpha-particle emitter (211)At. METHODS: Animals were intraperitoneally inoculated with approximately 1x10(7) cells of the cell line NIH:OVCAR-3. Four weeks later, the mice were given the first treatment. Six groups of animals were intraperitoneally injected with approximately 800, 3x approximately 267, approximately 400, 3x approximately 133, approximately 50 or 3x approximately 17 kBq (211)At-MX35 F(ab')(2) (n=18 in each group). The second and third injections for Groups 2, 4 and 6 were given 4 and 8 days after the first injection, respectively. As controls, animals were treated with unlabeled MX35 F(ab')(2) (n=12). Eight weeks after the last injection, the animals were sacrificed and the presence of macro- and microscopic tumors and ascites was determined. Blood counts were determined for each mouse in Groups 1 and 2 before the first injection and 3, 7, 11, 15 and 23 days after the first injection. The calculation of the mean absorbed dose to the bone marrow was based on the ratio between the (211)At-activity concentration in bone and blood [i.e., the bone-to-blood ratio (BBLR)] as well as that between the (211)At-activity concentration in bone marrow and blood [i.e., the bone-marrow-to-blood ratio (BMBLR)] and the cumulated activity and absorbed fraction of the alpha-particles emitted by (211)At in the bone marrow. RESULTS: The tumor-free fractions of animals were 56% and 41% when treated with approximately 800 kBq and 3x approximately 267 kBq (211)At-MX35 F(ab')(2), respectively; 39% and 28% when treated with approximately 400 kBq and 3x approximately 133 kBq (211)At-MX35 F(ab')(2), respectively; and 17% and 22% when treated with approximately 50 kBq or 3x approximately 17 kBq (211)At-MX35 F(ab')(2), respectively. The nadir of the white blood cell (WBC) counts was decreased (from 46% to 19%, compared with the baseline WBC counts) and delayed (from Day 4 to Day 11 after the first injection) during the fractionated treatment compared with the single-dose treatment. The percentage of injected activity per gram (%IA/g) for blood, bone and bone marrow all peaked 6 h after injection at 13.80+/-1.34%IA/g, 4.00+/-0.69%IA/g and 8.28+/-1.38%IA/g, respectively. The BBLR and BMBLR were 0.20+/-0.04 and 0.58+/-0.01, respectively. The mean absorbed dose to bone marrow was approximately 0.4 Gy after intraperitoneally injecting approximately 800 kBq (211)At-MX35 F(ab')(2). CONCLUSION: No advantage was observed in the therapeutic efficacy of using a fractionated regimen compared with a single administration, with the same total amount of administered activity. Alleviation of the myelotoxicity was observed during the fractionated regimen in terms of decreased suppression and delayed nadir of the WBC counts. No thrombocytopenia was observed during either regimen.
|
|
| 39. |
- Elgqvist, Jörgen, 1963, et al.
(författare)
-
Therapeutic efficacy and tumor dose estimations in radioimmunotherapy of intraperitoneally growing OVCAR-3 cells in nude mice with (211)At-labeled monoclonal antibody MX35
- 2005
-
Ingår i: J Nucl Med. - 0161-5505. ; 46:11, s. 1907-15
-
Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to investigate the therapeutic efficacy of-and to estimate the absorbed dose to-tumor cells from radioimmunotherapy (RIT) in an ovarian cancer model using the alpha-particle-emitting nuclide (211)At labeled to monoclonal antibody (mAb) MX35. Previous studies on mAb MOv18 did not allow for dosimetry because of antigen shedding in vitro. METHODS: Five-week-old female nude BALB/c nu/nu mice were inoculated intraperitoneally with 1 x 10(7) cells of the human tumor cell line OVCAR-3. Three weeks later, the animals were given approximately 400, 800, or 1,200 kBq of (211)At-labeled mAb MX35 intraperitoneally. As controls, one group of animals was injected with unlabeled mAb and another group was injected with phosphate-buffered saline (PBS). Another group was given approximately 400 kBq of (211)At labeled to the previously investigated mAb MOv18 for efficacy comparison. Two months after treatment, the animals were sacrificed and the presence of macroscopic and microscopic tumors, as well as ascites, was determined. The absorbed dose to tumor cells on the peritoneal surface was estimated in terms of the sum of a specific and a nonspecific contribution. The specific contribution, arising from mAbs binding to the antigenic sites on the cell membrane, was calculated using a dynamic compartment model developed in-house and Monte Carlo software. The model used as input values the number of mAbs injected into the abdominal cavity, N(mAb), the specific activity, A(sp), the association rate constant, k(on), and the maximal number of mAbs bound per cell, B(max)-all determined by in vitro experiments. This specific component of the absorbed dose was calculated for assumed cell cluster sizes with radii of 25, 50, and 100 microm. The nonspecific contribution to the absorbed dose was derived from unbound mAbs freely circulating in the abdominal cavity, also using the Monte Carlo software. RESULTS: In the control groups given unlabeled MX35 or PBS, all 18 animals had ascites, 6 of 9 animals in each group had macroscopic tumors, and all animals had microscopic growth. In the 3 groups given different amounts of (211)At-MX35, only 3 of 25 animals developed ascites. None of these animals had any sign of macroscopic tumors, but 8 had microscopic growth. In the group given (211)At-MOv18, no animals had ascites or macroscopic tumors, but 3 of 10 animals had microscopic tumors. After injecting 400 kBq of (211)At-MX35, the absorbed dose due to specific binding, for a cell cluster with a radius of 50 microm, ranged from 413 to 223 Gy between 0- and 45-microm distance from the cluster center, assuming a homogeneous distribution of (211)At-MX35 in the cluster. The contribution from unbound (211)At-MX35 and (211)At-MX35 only distributed on the cluster surface, for this cluster size, ranged from 7 to 14 Gy and from 29 to 94 Gy, between 0- and 45-microm distance from the cluster center, respectively. The calculated total absorbed doses are in a clinically relevant range and were effective as verified in the nude mice with subclinical intraperitoneal growth of OVCAR-3 cells. CONCLUSION: (211)At-MX35 injected intraperitoneally exhibits a high efficacy when treating micrometastatic growth of the ovarian cancer cell line OVCAR-3 on the peritoneum of nude mice.
|
|
| 40. |
|
|
| 41. |
|
|
| 42. |
|
|
| 43. |
|
|
| 44. |
|
|
| 45. |
|
|
| 46. |
- Palm, Stig, 1964, et al.
(författare)
-
Cell growth kinetics of the human cell line Colo-205 irradiated with photons and astatine-211 alpha-particles
- 2000
-
Ingår i: Anticancer Res. - 0250-7005. ; 20:3A, s. 1807-12
-
Tidskriftsartikel (refereegranskat)abstract
- Cell growth kinetics following Astatine-211 (211At, alpha-particle emitter) and photon irradiation were studied for the human colorectal cell line Colo-205. A growth assay using 96-well plates was chosen. The growth kinetics could be simulated by assuming certain fractions of cells with various proliferative capacities, i.e. from none up to 5 cell doublings, in addition to the defined survivors with remaining unlimited clonogenic capacity. No significant difference in cell growth characteristics was seen between 211At and photon irradiation. The cell doubling time, as calculated from the increment in optical density, was compared with the results from BrdU experiments in the early phases of growth (Tpot = 18.5 +/- 0.6 h for LDR (low dose rate) photon irradiated and 20.3 +/- 0.8 hours for sham-irradiated cells 40-45 hours post-irradiation) confirming the transient accelerated growth of irradiated cells. No statistically significant difference in growth was found between LDR, MDR (medium dose rate) and HDR (high dose rate) photon irradiation.
|
|
| 47. |
- Palm, Stig, 1964, et al.
(författare)
-
Effects of the alpha-particle emitter At-211 and low-dose-rate gamma-radiation on the human cell line Colo-205 as studied with a growth assay
- 1998
-
Ingår i: Anticancer Res. - 0250-7005. ; 18:3A, s. 1671-6
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The aim of this study was to investigate the biological effect of the alpha-particle-emitting isotope astatine-211 on the human cell line Colo-205 and to compare it with that of low-dose-rate gamma-radiation. MATERIALS AND METHODS: Plastic (PMMA) rotating phantoms were constructed, allowing precise dosimetry on a cellular level for both types of radiation. Growth assays using 96-well plates were used to estimate apparent cell survival for the two types of radiation. From this, the relative biological effect (RBE) could be estimated. RESULTS: Irradiation of the cells with 211At resulted in an RBE of 25.1 +/- 6.7 at 37% survival, and 17.3 +/- 2.5 at 10% survival, when compared with low-dose-rate gamma-irradiation. The absorbed dose at 37% survival, 0.12 Gy, corresponds to 2.2 traversals of alpha-particles through the cell nuclei. For cells irradiated with gamma-radiation (1 and 2 Gy), an apparent cell survival above unity was observed up to 50 hours post-irradiation, indicating a possible radiation hormesis effect. CONCLUSIONS: The RBE of 211At found in this growth-assay study was significantly higher than previously presented values. The difference might be due to the use of low-dose-rate gamma-radiation as reference. The RBE presented here could prove valuable when evaluating 211At-labelled compounds for radiotherapy.
|
|
| 48. |
|
|
| 49. |
|
|
| 50. |
- Palm, Stig, 1964, et al.
(författare)
-
In vitro effects of free 211At,211At-albumin and 211At-monoclonal antibody compared to external photon irradiation on two human cancer cell lines
- 2000
-
Ingår i: Anticancer Res. - 0250-7005. ; 20:2A, s. 1005-12
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The aim of this study was to perform various 211At irradiations of importance for the evaluation of 211At-radioimmunotherapy, and compare the effect with that of low linear energy transfer (LET) radiation. MATERIALS AND METHODS: All irradiations were performed on low-concentration single-cell suspensions. Growth assays using 96-well plates were used to estimate apparent cell survival. Centrifuge tube filters were used to estimate the cell uptake and binding of 211At. RESULTS: A relative biological effect (RBE) of 12 +/- 2 (Colo-205) and 5.3 +/- 0.7 (OVCAR-3) was found from 211At-albumin irradiations. There was a 174 +/- 28 times higher free 211At concentration in the cell fraction than in the surrounding medium. For 211At-MAb, an 8,000-30,000 times higher concentration in the cell fraction was achieved, compared to the medium. Corrected for the uptake, an average of 31 +/- 2 ([211At]-astatine) or 26 +/- 5 ([211At]-MAb) decays per cell were required for 37% survival of Colo-205 cells. An average of 19 +/- 3 decays ([211At]-astatine) were required per OVCAR-3 cell. CONCLUSIONS: Cell uptake and binding of 211At was unexpectedly high, possibly favouring its therapeutic use. The binding is probably to the cell surface. The RBE is 5.3 +/- 0.7 for OVCAR-3 and 12 +/- 2 for Colo-205 cells.
|
|
