Dataset Information

Whole-Body and Microenvironmental Localization of Radium-223 in Naive and Mouse Models of Prostate Cancer Metastasis.

ABSTRACT: BACKGROUND:Bone-metastatic, castration-resistant prostate cancer (bmCRPC) represents a lethal stage of the most common noncutaneous cancer in men. The recent introduction of Radium-223 dichloride, a bone-seeking alpha particle (?)-emitting radiopharmaceutical, demonstrates statistically significant survival benefit and palliative effect for bmCRPC patients. Clinical results have established safety and efficacy, yet questions remain regarding pharmacodynamics and dosing for optimized patient benefit. METHODS:We elucidated the biodistribution of (223)Ra as well as interaction with the bone and tumor compartments in skeletally mature mice (C57Bl/6 and CD-1, n = 3-6) and metastasis models (LNCaP and PC3, n = 4). Differences in uptake were evaluated by µCT and histological investigation. Novel techniques were leveraged on whole-mount undecalcified cryosections to determine microdistribution of Radium-223. All statistical tests were two-sided. RESULTS:(223)Ra uptake in the bones (>30% injected activity per gram) at 24 hours was also accompanied by non-negligible remnant activity in the kidney (2.33% ± 0.36%), intestines (5.73% ± 2.04%), and spleen (10.5% ± 5.9%) Skeletal accumulation across strains did not correspond with bone volume or surface area but instead to local blood vessel density (P = .04). Microdistribution analysis by autoradiography and ? camera revealed targeting of the ossifying surfaces adjacent to the epiphyseal growth plate. In models of PCa metastasis, radioactivity does not localize directly within tumors but instead at the apposite bone surface. Osteoblastic and lytic lesions display similar intensity, which is comparable with uptake at sites of normal bone remodeling. CONCLUSIONS:Profiling the macro- and microdistribution of (223)Ra in healthy and diseased models has important implications to guide precision application of this emerging ?-therapy approach for bmCRPC and other bone metastastic diseases.

SUBMITTER: Abou DS

PROVIDER: S-EPMC4849807 | biostudies-literature | 2016 May

REPOSITORIES: biostudies-literature

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Whole-Body and Microenvironmental Localization of Radium-223 in Naïve and Mouse Models of Prostate Cancer Metastasis.

Abou Diane S DS Ulmert David D Doucet Michele M Hobbs Robert F RF Riddle Ryan C RC Thorek Daniel L J DL

Journal of the National Cancer Institute 20151218 5

<h4>Background</h4>Bone-metastatic, castration-resistant prostate cancer (bmCRPC) represents a lethal stage of the most common noncutaneous cancer in men. The recent introduction of Radium-223 dichloride, a bone-seeking alpha particle (α)-emitting radiopharmaceutical, demonstrates statistically significant survival benefit and palliative effect for bmCRPC patients. Clinical results have established safety and efficacy, yet questions remain regarding pharmacodynamics and dosing for optimized pati ...[more]

PMID: 26683407

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Project description:BackgroundMetastatic prostate cancer in bone is difficult to treat as the tumor cells are relatively resistant to hormonal or chemotherapies when compared to primary prostate cancer. Irreversible electroporation (IRE) is a minimally invasive ablation procedure that has potential applications in the management of prostate cancer in bone. However, a common limitation of IRE is tumor recurrence, which arises from incomplete ablation that allows remaining cancer cells to proliferate. In this study, we combined IRE with radium-223 (Ra-223), a bone-seeking radionuclide that emits short track length alpha particles and thus is associated with reduced damage to the bone marrow and evaluated the impact of the combination treatment on bone-forming prostate cancer tumors.MethodsThe antitumor activity of IRE and Ra-223 as single agents and in combination was tested in vitro against three bone morphogenetic protein 4 (BMP4)-expressing prostate cancer cell lines (C4-2B-BMP4, Myc-CaP-BMP4, and TRAMP-C2-BMP4). Similar evaluation was performed in vivo using a bone-forming C4-2B-BMP4 tumor model in nude mice.ResultsIRE and Ra-223 as monotherapy inhibited prostate cancer cell proliferation in vitro, and their combination resulted in significant reduction in cell viability compared to monotherapy. In vivo evaluation revealed that IRE with single-dose administration of Ra-233, compared to IRE alone, reduced the rate of tumor recurrence by 40% following initial apparent complete ablation and decreased the rate of proliferation of incompletely ablated tumor as quantified in Ki-67 staining (53.58 ± 16.0% for IRE vs. 20.12 ± 1.63%; for IRE plus Ra-223; p = 0.004). Histological analysis qualitatively showed the enhanced killing of tumor cells adjacent to bone by Ra-223 compared to those treated with IRE alone.ConclusionIRE in combination with Ra-223, which enhanced the destruction of cancer cells that are adjacent to bone, resulted in reduction of tumor recurrence through improved clearance of proliferative cells in the tumor region.

Project description:BackgroundBone-targeting radiotherapy with Radium-223 (Rad-223), a radioisotope emitting genotoxic alpha-radiation with limited tissue penetrance (∼100 µm), prolongs the survival of patients with metastatic prostate cancer (PCa). Confoundingly, the clinical response to Rad-223 is often followed by detrimental relapse and progression, and whether Rad-223 causes tumor-cell directed cytotoxicity in vivo remains unclear. We hypothesized that limited radiation penetrance in situ defines outcome.MethodsWe tested Rad-223 overall response by PC3 and C4-2B human PCa cell lines in mouse bones (n = 5-18 tibiae per group). Rad-223 efficacy at subcellular resolution was determined by intravital microscopy analysis of dual-color fluorescent PC3 cells (n = 3-4 mice per group) in tissue-engineered bone constructs. In vivo data were fed into an in silico model to predict Rad-223 effectiveness in lesions of different sizes (1-27, 306 initial cells; n = 10-100 simulations) and the predictions validated in vivo by treating PCa tumors of varying sizes in bones (n = 10-14 tibiae per group). Statistical tests were performed by two-sided Student t test or by one-way ANOVA followed by Tukey's post-hoc test.ResultsRad-223 (385 kBq/kg) delayed the growth (means [SD]; comparison with control-treated mice) of PC3 (6.7 × 105[4.2 × 105] vs 2.8 × 106 [2.2 × 106], P = .01) and C4-2B tumors in bone (7.7 × 105 [4.0 × 105] vs 3.5 × 106 [1.3 × 106], P < .001). Cancer cell lethality in response to Rad-223 (385 kBq/kg) was profound but zonally confined along the bone interface compared with the more distant tumor core, which remained unperturbed (day 4; 13.1 [2.3%] apoptotic cells, 0-100 µm distance from bone vs 3.6 [0.2%], >300 µm distance; P = .01).In silico simulations predicted greater efficacy of Rad-223 on single-cell lesions (eradication rate: 88.0%) and minimal effects on larger tumors (no eradication, 16.2% growth reduction in tumors of 27 306 cells), as further confirmed in vivo for PC3 and C4-2B tumors.ConclusionsMicro-tumors showed severe growth delay or eradication in response to Rad-223, whereas macro-tumors persisted and expanded. The relative inefficacy in controlling large tumors points to application of Rad-223 in secondary prevention of early bone-metastatic disease and regimens co-targeting the tumor core.

Project description:BackgroundThe treatment of metastatic castration-resistant prostate cancer has changed with the introduction of radium-223, cabazitaxel, abiraterone and enzalutamide. To assess value for money, their cost effectiveness in patients with metastatic castration-resistant prostate cancer previously treated with docetaxel from the Dutch societal perspective was investigated.MethodsA cost-effectiveness analysis was conducted using efficacy, symptomatic skeletal-related event and safety data obtained from indirect treatment comparisons. Missing skeletal-related event data for cabazitaxel were conservatively assumed to be identical to radium-223. A Markov model combined these clinical inputs with Dutch-specific resource use and costs for metastatic castration-resistant prostate cancer treatment from a societal perspective. Total quality-adjusted life-years and costs in 2017 euros were calculated over a 5-year (lifetime) time horizon.ResultsRadium-223 resulted in €6092 and €4465 lower costs and 0.02 and 0.01 higher quality-adjusted life-years compared with abiraterone and cabazitaxel, respectively, demonstrating dominance of radium-223. Sensitivity analyses reveal a 64% (54%) chance of radium-223 being cost effective compared with abiraterone (cabazitaxel) at the informal €80,000 willingness-to-pay threshold. Compared with enzalutamide, radium-223 resulted in slightly lower quality-adjusted life-years (-0.06) and €7390 lower costs, revealing a 61% chance of radium-223 being cost effective compared with enzalutamide. The lower costs of radium-223 compared with abiraterone and enzalutamide are driven by lower drug costs and prevention of expensive skeletal-related events. Compared with cabazitaxel, the lower costs of radium-223 are driven by lower costs of the drug, administration and adverse events.ConclusionRadium-223 may be a less costly treatment strategy offering similar gains in health benefits compared with abiraterone, cabazitaxel and enzalutamide in patients with metastatic castration-resistant prostate cancer previously treated with docetaxel from the Dutch societal perspective.

Dataset Information

Whole-Body and Microenvironmental Localization of Radium-223 in Naive and Mouse Models of Prostate Cancer Metastasis.

Publications

Whole-Body and Microenvironmental Localization of Radium-223 in Naïve and Mouse Models of Prostate Cancer Metastasis.

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