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223 Ra-dichloride is an α-emitter therapy approved for the treatment of castration-resistant prostate cancer with symptomatic bone metastases. 223 Ra-dichloride is the first targeted α-therapy for this indication with evidence of benefit in overall survival. The administration is intravenous, and extravasation can cause severe injuries such as tissue necrosis. To prevent this side effect, some procedures can be performed according to the guideline of the European Association of Nuclear Medicine. Ionizing radiation is a well-established risk factor for the development of cutaneous squamous cell carcinoma, but surprisingly there are few reports of local adverse effects related to extravasation of radiotherapies at the injection sites. Recently, a possible case of cutaneous cancer was observed after 223 Ra-dichloride extravasation. Methods: To complement the prevention of extravasation, we developed a standardized technique to be performed before the injection of 223 Ra. Results: Our technique was successfully applied to the study population, and no apparent extravasation was seen. Conclusion: Our study suggests that use of this standardized technique before administration of 223 Ra is helpful in preventing extravasation during this treatment., (© 2024 by the Society of Nuclear Medicine and Molecular Imaging.)

Background: Radium-223 dichloride (Ra-223) prolongs overall survival (OS) in metastatic castration-resistant prostate cancer (mCRPC) with symptomatic bone metastases. However, there is considerable variation in outcomes among individuals. We aimed to evaluate the prognostic determinants associated with patient survival following National Health Insurance (NHI) reimbursement for Ra-223 therapy in Taiwan., Methods: Patients with mCRPC who underwent Ra-223 treatment at Taipei Veterans General Hospital were retrospectively enrolled. Each intravenous Ra-223 dose was administered at 55 kBq/kg at 4-week intervals. Clinical outcomes were obtained from medical records; potential prognostic factors for survival were assessed. Kaplan-Meier analysis was used to generate cumulative survival curves; between-group differences were evaluated using the Chi-squared test. Statistical significance was set at p < 0.05., Results: Seventy-six patients underwent Ra-223 therapy; 62 patients received NHI reimbursement and the remainder self-paid. Fifty patients (65.8%) completed six cycles of treatment; 26 (34.2%) received 1 to 5 cycles. Mortality occurred in 47 patients. Factors significantly associated with survival included ≤five bone metastases ( p = 0.0018), baseline prostate-specific antigen (PSA) ≤36 ng/mL ( p = 0.0004), baseline alkaline phosphate (ALP) <115 U/L ( p = 0.0007), and baseline hemoglobin (Hb) >12 g/dL ( p = 0.0029). Patients who completed six cycles of treatment achieved significantly higher OS compared to those who did not ( p < 0.0001). There has been a 4.4-fold increase in the number of patients since reimbursement began; there was no significant difference in OS between patients who received NHI reimbursement and those who self-paid., Conclusion: Administration of Ra-223 demonstrates considerable potential to extend the survival of patients with mCRPC. Survival outcomes may be influenced by various prognostic factors. However, no significant difference in OS was observed subsequent to reimbursement of Ra-223 therapy for mCRPC through the NHI system in Taiwan., Competing Interests: Conflicts of interest: Dr. William J. Huang, an editorial board member at Journal of the Chinese Medical Association , had no role in the peer review process of or decision to publish this article. The other authors declare that they have no conflicts of interest related to the subject matter or materials discussed in this article., (Copyright © 2024, the Chinese Medical Association.)

Objective: Radium-223 (Ra-223) is an important treatment modality for bone-dominant metastatic castration-resistant prostate cancer (mCRPC). However, there is currently a lack of effective markers to monitor treatment response during treatment. We aim to investigate the response in prostate-specific antigen doubling time (PSADT) as a potential marker for assessing Ra-223 treatment in mCRPC patients., Methods: We retrospectively collected data from mCRPC patients who underwent radium treatment at our institution between August 2020 and June 2023. Prostate-specific antigen (PSA) measurements prior to treatment and during treatment were collected. Baseline PSADT was calculated from PSA measurements prior to Ra-223 treatment; interim PSADT was calculated from PSA measurements before Ra-223 treatment and prior to the fourth course injection. Overall survival was calculated from the start of treatment to the date of death. Univariable and multivariable analysis using the Cox proportional hazards model were performed to examine the association of factors with overall survival., Results: We included 35 patients from our institution, with a median overall survival of 13.3 months. Eighteen (51.4%) completed all six courses of treatment. PSA dynamic response (interim PSADT > baseline PSADT or decreased PSA) was observed in 20 patients. Overall survival was associated with a PSA dynamic response (HR = 0.318, 95% CI 0.133-0.762, p = 0.010) when compared to patients without response., Conclusions: Dynamic changes in PSADT were associated with survival in mCRPC patients receiving radium therapy. Comparing interim and baseline PSADT could serve as a valuable marker for determining treatment benefits., (© 2024. The Author(s), under exclusive licence to The Author(s) under exclusive licence to The Japanese Society of Nuclear Medicine.)

Targeted radionuclide therapy (TRT) has significantly evolved from its beginnings with iodine-131 to employing carrier molecules with beta emitting isotopes like lutetium-177. With the success of Lu-177-DOTATATE for neuroendocrine tumors and Lu-177-PSMA-617 for prostate cancer, several other beta emitting radioisotopes, such as Cu-67 and Tb-161, are being explored for TRT. The field has also expanded into targeted alpha therapy (TAT) with agents like radium-223 for bone metastases in prostate cancer, and several other alpha emitter radioisotopes with carrier molecules, such as Ac-225, and Pb-212 under clinical trials. Despite these advancements, the scope of TRT in treating diverse solid tumors and integration with other therapies like immunotherapy remains under investigation. The success of antibody-drug conjugates further complements treatments with TRT, though challenges in treatment optimization continue., Competing Interests: Disclosure G. Sgouros is a founder of, and holds equity in, Rapid. He serves as a member of Rapid’s Board of Directors. H. Song is a consultant for Progenics Pharmaceuticals, Inc (Lantheus). Acknowledgement George Sgouros acknowledges the funding support of National Institute of Health (P01CA272222)., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The clinical success of [ 223 Ra]RaCl 2 (Xofigo®) for the palliative treatment of bone metastases in patients with prostate cancer has highlighted the therapeutic potential of α-particle emission. Expanding the applicability of radium-223 in Targeted Alpha Therapy of non-osseous tumors is followed up with significant interest, as it holds the potential to unveil novel treatment options in the comprehensive management of cancer. Moreover, the use of barium radionuclides, like barium-131 and -135m, is still unfamiliar in nuclear medicine applications, although they can be considered as radium-223 surrogates for imaging purposes. Enabling these applications requires the establishment of chelators able to form stable complexes with radium and barium radionuclides. Until now, only a limited number of ligands have been suggested and these molecules have been primarily inspired by existing structures known for their ability to complex large metal cations. However, a systematic inspection of chelators specifically tailored to Ra 2+ and Ba 2+ has yet to be conducted. This work delves into a comprehensive investigation of a series of small organic ligands, aiming to unveil the coordination preferences of both radium-223 and barium-131/135m. Electronic binding energies of both metal cations to each ligand were theoretically computed via Density Functional Theory calculations (COSMO-ZORA-PBE-D3/TZ2P), while thermodynamic stability constants were experimentally determined for Ba 2+ -ligand complexes by potentiometry, NMR and UV-Vis spectroscopies. The outcomes revealed malonate, 2-hydroxypyridine 1-oxide and picolinate as the most favorable building blocks to design multidentate chelators. These findings serve as foundation guidelines, propelling the development of cutting-edge radium-223- and barium-131/135m-based radiopharmaceuticals for Targeted Alpha Therapy and theranostics of cancer., Competing Interests: Declaration of competing interest The authors have no competing interests to declare., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Several life-prolonging therapies for metastatic castration-resistant prostate cancer (mCRPC) are available, including radium-223 dichloride ( 223 Ra), which was approved based on phase 3 data demonstrating improved overall survival (OS) and a favorable safety profile. To date, real-world evidence for 223 Ra use in Taiwan is from three studies of <50 patients. This observational study (NCT04232761) enrolled male patients with histologically/cytologically confirmed mCRPC with bone metastases from centers across Taiwan. 223 Ra was prescribed as part of routine practice by investigators. Patients with prior 223 Ra treatment were excluded. The primary objective was to assess 223 Ra safety; secondary objectives evaluated efficacy parameters, including OS. Overall, 224 patients were enrolled. Most patients had an Eastern Cooperative Oncology Group performance status of 0/1 (79.0%) and ≤20 bone metastases (69.2%); no patients had visceral metastases. 223 Ra was first- or second-line therapy in 23.2% and 47.7% of patients, respectively. The total proportion of patients who received 5-6 223 Ra cycles was 68.8%; this proportion was greater with first-line use (84.3%) than second- (65.7%) or third-/fourth-line use (64.1%). More chemotherapy-naïve patients (61.9%) completed the 6-cycle 223 Ra treatment than chemotherapy-exposed patients (56.7%). Any-grade treatment-emergent adverse events (TEAEs) and serious TEAEs occurred in 54.0% and 28.6% of patients, respectively, while 12% experienced 223 Ra-related adverse events. Median OS was 15.7 months (95% confidence interval 12.13-19.51); patients receiving 5-6 223 Ra injections and earlier 223 Ra use had longer OS than those receiving fewer injections and later 223 Ra use. 223 Ra provides a well-tolerated and effective treatment for Taiwanese patients with mCRPC and bone metastases., (© 2024 The Author(s). International Journal of Cancer published by John Wiley & Sons Ltd on behalf of UICC.)

The checkpoint immunotherapeutic pembrolizumab induces responses in a small minority of patients with metastatic castration-resistant prostate cancer (mCRPC). Radium-223 (R223) may increase immunogenicity of bone metastases and increase pembrolizumab (P) activity. In a randomized phase II study, we assessed the effect of R223+P compared with R223 on tumor immune infiltration, safety, and clinical outcomes in patients with mCRPC. The primary endpoint was differences in CD4+ and CD8+ T-cell infiltrate in 8-week versus baseline bone metastasis biopsies; secondary endpoints were safety, radiographic progression-free survival (rPFS), and overall survival (OS). Of the 42 treated patients (29 R223+P, 13 R223), 18 R223+P and 8 R223 patients had evaluable paired tumor biopsies. Median fold-change of CD4+ T cells was -0.7 (range: -9.3 to 4.7) with R223+P and 0.1 (-11.1 to 3.7) with R223 (P = 0.66); for CD8+ T cells, median fold-change was -0.6 (-7.4 to 5.3) with R223+P and -1.3 (-3.1 to 4.8) with R223 (P = 0.66). Median rPFS and OS was 6.1 (95% confidence interval: 2.7-11.0) and 16.9 months [12.7-not reached (NR)], respectively, with R223+P and 5.7 (2.6-NR) and 16.0 (9.0-NR), respectively, with R223. Although R223+P was well tolerated with no unexpected toxicity, the combination did not improve efficacy. High-dimensional flow cytometry demonstrated minimal immune modulation with R223, whereas R223+P induced CTLA-4 expression on circulating CD4+ T cells. Clinical responders possessed lower circulating frequencies of Ki67+ T and myeloid cells at baseline and higher circulating frequencies of TIM-3+ T and myeloid cells by week 9. Although R223+P did not induce T-cell infiltration into the tumor microenvironment, exhaustion of induced peripheral T-cell immune responses may dampen the combination's clinical activity., (©2024 The Authors; Published by the American Association for Cancer Research.)

Background: Radium-223 and taxane chemotherapy each improve survival of patients with metastatic castration-resistant prostate cancer (mCRPC). Whether the radium-223-taxane sequence could extend survival without cumulative toxicity was explored., Methods: The global, prospective, observational REASSURE study (NCT02141438) assessed real-world safety and effectiveness of radium-223 in patients with mCRPC. Using data from the prespecified second interim analysis (data cutoff, March 20, 2019), hematologic events and overall survival (OS) were evaluated in patients who were chemotherapy-naive at radium-223 initiation and subsequently received taxane chemotherapy starting ≤90 days ("immediate") or >90 days ("delayed") after the last radium-223 dose., Results: Following radium-223 therapy, 182 patients received docetaxel (172 [95%]) and/or cabazitaxel (44 [24%]); 34 patients (19%) received both. Seventy-three patients (40%) received immediate chemotherapy and 109 patients (60%) received delayed chemotherapy. Median time from last radium-223 dose to first taxane cycle was 3.6 months (range, 0.3-28.4). Median duration of first taxane was 3.7 months (range, 0-22.0). Fourteen patients (10 in the immediate and four in the delayed subgroup) had grade 3/4 hematologic events during taxane chemotherapy, including neutropenia in two patients in the delayed subgroup and thrombocytopenia in one patient in each subgroup. Median OS was 24.3 months from radium-223 initiation and 11.8 months from start of taxane therapy., Conclusions: In real-world clinical practice settings, a heterogeneous population of patients who received sequential radium-223-taxane therapy had a low incidence of hematologic events, with a median survival of 1 year from taxane initiation. Thus, taxane chemotherapy is a feasible option for those who progress after radium-223., Clinical Trial Registration: ClinicalTrials.gov identifier NCT02141438., Plain Language Summary: Radium-223 and chemotherapy are treatment options for metastatic prostate cancer, which increase survival but may affect production of blood cells as a side effect. We wanted to know what would happen if patients received chemotherapy after radium-223. Among the 182 men treated with radium-223 who went on to receive chemotherapy, only two men had severe side effects affecting white blood cell production (neutropenia) during chemotherapy. On average, the 182 men lived for 2 years after starting radium-223 and 1 year after starting chemotherapy. In conclusion, patients may benefit from chemotherapy after radium-223 treatment without increasing the risk of side effects., (© 2024 The Authors. Cancer published by Wiley Periodicals LLC on behalf of American Cancer Society.)

Background/aim: Radium-223 therapy has been reported to improve prognosis in patients with castration-resistant prostate cancer (CRPC) and bone metastases. Occasionally, radium-223 and androgen receptor signaling inhibitors (ARSIs) are used in combination for disease control, but the efficacy of this combination is unclear. This study assessed the efficacy of the addition of enzalutamide in patients treated with radium-223., Patients and Methods: We included patients with CRPC and bone metastases who were treated with radium-223 at our institution. Patients were assigned to the enzalutamide combination group or non-combination group. We compared progression-free survival (PFS), overall survival (OS), and the completion rate of radium-223 between the two groups., Results: In total, 39 patients with CRPC were included in this retrospective study. The median follow-up duration was 8.8 months. The enzalutamide combination and non-combination groups included 22 (56.4%) and 17 patients (43.6%), respectively. Median PFS was 11.3 months [95% confidence interval (CI)=3.9-19.9] in the combination group, versus 3.0 months (95%CI=1.9-5.5) in the non-combination group (p=0.004). Median OS did not significantly differ between the groups. The radium-223 completion rate was higher in the combination group than in the non-combination group (72.7% vs. 35.3%, p=0.026)., Conclusion: The combined use of enzalutamide with radium-223 therapy improved PFS and treatment completion rates in patients with CRPC and bone metastases. This combination may be associated with a more favorable prognosis., (Copyright © 2024 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Objective: Radium-223 is a first alpha-emitting radionuclide treatment for metastatic castration-resistant prostate cancer (mCRPC) patients with bone metastases. Although the spread-based bone scan index (BSI) and novel index of the intensity-based two-dimensional total bone uptake (2D-TBU) from bone scintigraphy may provide useful input in radium-223 treatment, they have not been evaluated in detail yet. This study aimed to fill this gap by evaluating BSI and 2D-TBU in patients treated with radium-223., Methods: Twenty-seven Japanese patients with mCRPC treated with radium-223 were retrospectively analyzed. The patients were evaluated via blood tests and bone scans at baseline and 3 cycles intervals of treatment. BSI and 2D-TBU were analyzed via VSBONE BSI in terms of correlations, response to radium-223 treatment, association with treatment completion, and the Kaplan-Meier survival analysis was performed., Results: Nineteen patients (70.4%) completed six cycles of radium-223 treatment, whereas eight patients (29.6%) did not complete the treatment regimen. A significant difference in baseline BSI and 2D-TBU was observed between these groups of patients. Both BSI and 2D-TBU were highly correlated (r = 0.96, p < 0.001). Univariate analysis showed an association between radium-223 completion in median BSI and 2D-TBU values (p = 0.015) and completion percentage differences (91.7% vs. 45.5%; p = 0.027). The Kaplan-Meier product limit estimator showed that the median overall survival was 25.2 months (95% CI 14.0-33.6 months) in the completion group and 7.5 months (95% CI 3.3-14.2 months) in the without completion group (p < 0.001). The overall survival based on median cutoff levels showed a significant difference in 2D-TBU (p = 0.007), but not in BSI (p = 0.15)., Conclusions: The 2D-TBU may offer advantages over BSI in classifying patients towards radium-223 treatment based on the degree of progression of bone metastases. This study supports the importance of preliminary assessment of bone metastasis status using BSI and 2D-TBU extracted from VSBONE BSI for radium-223 treatment decisions., (© 2024. The Author(s), under exclusive licence to The Author(s) under exclusive licence to The Japanese Society of Nuclear Medicine.)

Background: Radium-223 is an active therapy option for bone metastatic castration-resistant prostate cancer (mCRPC). The lack of adequate biomarkers for patient selection and response assessment are major drawbacks for its use., Objective: To assess the prognostic value of bone metabolism biomarkers (BMBs) in ra-223-treated mCRPC patients., Design, Setting, and Participants: A prospective cohort study of mCRPC patients treated with Ra-223 (PRORADIUM study: NCT02925702) was conducted., Outcome Measurements and Statistical Analysis: The main objective of the study was to evaluate the association between high (≥median) baseline values in at least three bone formation (bone alkaline phosphatase [BAP] and C-terminal type-I collagen propeptide) and bone resorption (N-terminal telopeptide and pyridinoline) biomarkers, and survival. The independent prognostic value of each BMB was also assessed. The association with time to radiographic, clinical, and prostate-specific antigen (PSA) progression; time to skeletal-related events; and PSA response were secondary objectives. Multivariable (MV) Cox-regression models were evaluated., Results and Limitations: A total of 169 patients were included. Of the patients, 70.4% received Ra-223 in second/third line; 144 (85.2%) were Eastern Cooperative Oncology Group 0-1, 126 (74.6%) were in pain, and 80 (47.5%) had more than ten bone metastases. Sixty-seven (39.6%) patients had elevation in at least three BMBs. The median overall survival was 12.1 mo (95% confidence interval [CI]: 10-14.7). No association was observed with other treatment-related secondary outcome parameters. Patients with high values in three or more BMBs had significantly worse survival (9.9 vs 15.2 mo; hazard ratio [HR]: 1.8 [95% CI: 1.3-2.5]; p < 0.001) in the univariate analysis, but not independent in the MV analysis (HR: 1.33; 95% CI: 0.89-2; p = 0.181). High baseline BAP was the only biomarker associated with survival in the MV model (HR: 1.89; 95% CI: 1.28-2.79; p = 0.001). Addition of BAP to the MV clinical model increased the area under the receiver operating characteristic curve 2-yr value from 0.667 to 0.755 (p = 0.003)., Conclusions: Biomarkers of bone formation, especially BAP, have prognostic value in mCRPC patients treated with radium-223. Its predictive value remains to be assessed, ideally in prospective, adequately powered, randomised clinical trials., Patient Summary: In this study, we evaluate the role of bone metabolism biomarkers to help improve the use of radium-223 as therapy for advanced prostate cancer. We found that bone alkaline phosphatase may be a suitable tool., (Copyright © 2023 European Association of Urology. Published by Elsevier B.V. All rights reserved.)

Personalized dose-based treatment planning requires accurate and reproducible noninvasive measurements to ensure safety and effectiveness. Dose estimation using SPECT is possible but challenging for alpha (α)-particle-emitting radiopharmaceutical therapy (α-RPT) because of complex γ-emission spectra, extremely low counts, and various image-degrading artifacts across a plethora of scanner-collimator configurations. Through the incorporation of physics-based considerations and skipping of the potentially lossy voxel-based reconstruction step, a recently developed projection-domain low-count quantitative SPECT (LC-QSPECT) method has the potential to provide reproducible, accurate, and precise activity concentration and dose measures across multiple scanners, as is typically the case in multicenter settings. To assess this potential, we conducted an in silico imaging trial to evaluate the LC-QSPECT method for a 223 Ra-based α-RPT, with the trial recapitulating patient and imaging system variabilities. Methods: A virtual imaging trial titled In Silico Imaging Trial for Quantitation Accuracy (ISIT-QA) was designed with the objectives of evaluating the performance of the LC-QSPECT method across multiple scanner-collimator configurations and comparing performance with a conventional reconstruction-based quantification method. In this trial, we simulated 280 realistic virtual patients with bone-metastatic castration-resistant prostate cancer treated with 223 Ra-based α-RPT. The trial was conducted with 9 simulated SPECT scanner-collimator configurations. The primary objective of this trial was to evaluate the reproducibility of dose estimates across multiple scanner-collimator configurations using LC-QSPECT by calculating the intraclass correlation coefficient. Additionally, we compared the reproducibility and evaluated the accuracy of both considered quantification methods across multiple scanner-collimator configurations. Finally, the repeatability of the methods was evaluated in a test-retest study. Results: In this trial, data from 268 223 RaCl 2 treated virtual prostate cancer patients, with a total of 2,903 lesions, were used to evaluate LC-QSPECT. LC-QSPECT provided dose estimates with good reproducibility across the 9 scanner-collimator configurations (intraclass correlation coefficient > 0.75) and high accuracy (ensemble average values of recovery coefficients ranged from 1.00 to 1.02). Compared with conventional reconstruction-based quantification, LC-QSPECT yielded significantly improved reproducibility across scanner-collimator configurations, accuracy, and test-retest repeatability ([Formula: see text] Conclusion: LC-QSPECT provides reproducible, accurate, and repeatable dose estimations in 223 Ra-based α-RPT as evaluated in ISIT-QA. These findings provide a strong impetus for multicenter clinical evaluations of LC-QSPECT in dose quantification for α-RPTs., (© 2024 by the Society of Nuclear Medicine and Molecular Imaging.)

Importance: Innovative nuclear medicine services offer substantial clinical value to patients. However, these advancements often come with high costs. Traditional payment strategies do not incentivize medical institutes to provide new services nor determine the fair price for payers. A shift towards a value-based pricing strategy is imperative to address these challenges. Such a strategy would reconcile the cost of innovation with incentives, foster transparent allocation of healthcare resources, and expedite the accessibility of essential medical services., Objective: This study aims to develop and present a comprehensive, value-based pricing model for new nuclear medicine services, illustrated explicitly through a case study of the radium [223Ra] treatment for bone metastases. In constructing the pricing model, we have considered three primary value determinants: the cost of the new service, associated service risk, and the difficulty of the service provision. Our research can help healthcare leaders design an evidence-based Fee-For-Service (FFS) payment reference pricing with nuclear medicine services and price adjustments., Design, Setting and Participants: This multi-center study was conducted from March 2021 to February 2022 (including consultation meetings) and employed both qualitative and quantitative methodologies. We organized focus group consultations with physicians from nuclear medicine departments in Beijing, Chongqing, Guangzhou, and Shanghai to standardize the treatment process for radium [223Ra] bone metastases. We used a specially designed 'Radium Nuclide [223Ra] Bone Metastasis Data Collection Form' to gather nationwide resource consumption data to extract information from local databases. Four interviews with groups of experts were conducted to determine the add-up ratio, based on service risk and difficulty. The study organized consultation meeting with key stakeholders, including policymakers, service providers, clinical researchers, and health economists, to finalize the pricing equation and the pricing result of radium [223Ra] bone metastases service., Main Outcomes and Measures: We developed and detailed a pricing equation tailored for innovative services in the nuclear medicine department, illustrating its application through a step-by-step guide. A standardized service process was established to ensure consistency and accuracy. Adhering to best practice guidelines for health cost data analysis, we emphasized the importance of cross-validation of data, where validated data demonstrated less variation. However, it required a more advanced health information system to manage and analyze the data inputs effectively., Results: The standardized service of radium [223Ra] bone metastases includes: pre-injection assessment, treatment plan, administration, post-administration monitoring, waste disposal and monitoring. The average duration for each stage is 104 min, 39 min, 25 min, 72 min and 56 min. A standardized monetary value for medical consumables is 54.94 yuan ($7.6), and the standardised monetary value (medical consumables cost plus human input) is 763.68 yuan ($109.9). Applying an agreed value add-up ratio of 1.065, the standardized value is 810.19 yuan ($116.9). Feedback from a consultation meeting with policymakers and health economics researchers indicates a consensus that the pricing equation developed was reasonable and well-grounded., Conclusion: This research is the first study in the field of nuclear medicine department pricing methodology. We introduce a comprehensive value-based nuclear medical service pricing method and use radium[223Ra] bone metastases treatment pricing in China as a case study. This study establishes a novel pricing framework and provides practical instructions on its implementation in a real-world healthcare setting., (© 2024. The Author(s).)

Objectives: The aim of this study was to generate an objective method to describe MRI data to assess response in the vertebrae of patients with metastatic hormone sensitive prostate cancer (mHSPC), treated with external beam radiation therapy and systemic therapy with Radium-223 and to correlate changes with clinical outcomes., Methods: Three sets of whole-body MRI (WBMRI) images were utilized from 25 patients from the neo-adjuvant Androgen Deprivation Therapy pelvic Radiotherapy and RADium-223 (ADRRAD) clinical trial: MRI1 (up to 28 days before Radium-223), MRI2, and MRI3 (2 and 6 months post completion of Radium-223). Radiological response was assessed based on post baseline MRI images. Vertebrae were semi-automatically contoured in the sagittal T1-weighted (T1w) acquisitions, MRI intensity was measured, and spinal cord was used to normalize the measurements. The relationship between MRI intensity vs time to biochemical progression and radiology response was investigated. Survival curves were generated and splitting measures for survival and biochemical progression investigated., Results: Using a splitting measure of 1.8, MRI1 was found to be a reliable quantitative indicator correlating with overall survival (P = 0.023) and biochemical progression (P = 0.014). MRI (3-1) and MRI (3-2) were found to be significant indicators for patients characterized by progressive/non-progressive disease (P = 0.021, P = 0.004) and biochemical progression within/after 12 months (P = 0.007, P = 0.001)., Conclusions: We have identified a potentially useful objective measure of response on WBMRI of vertebrae containing bone metastases in mHSPC which correlates with survival/progression (prognostic) and radiology response (predictive)., Advances in Knowledge: Measurements of T1w WBMRI normalized intensity may allow identifying potentially useful response biomarkers correlating with survival, radiological response and biochemical progression., (© The Author(s) 2024. Published by Oxford University Press on behalf of the British Institute of Radiology.)

Radium-223 ( 223 Ra) is the first-in-class alpha-emitter to mediate tumor eradication, which is commonly thought to kill tumor cells by directly cleaving double-strand DNA. However, the immunogenic characteristics and cell death modalities triggered by 223 Ra remain unclear. Here, it is reported that the 223 Ra irradiation induces the pro-inflammatory damage-associated molecular patterns including calreticulin, HMGB1, and HSP70, hallmarks of tumor immunogenicity. Moreover, therapeutic 223 Ra retards tumor progression by triggering pyroptosis, an immunogenic cell death. Mechanically, 223 Ra-induced DNA damage leads to the activation of stimulator of interferon genes (STING)-mediated DNA sensing pathway, which is critical for NLRP3 inflammasome-dependent pyroptosis and subsequent DCs maturation as well as T cell activation. These findings establish an essential role of STING in mediating alpha-emitter 223 Ra-induced antitumor immunity, which provides the basis for the development of novel cancer therapeutic strategies and combinatory therapy., (© 2023 The Authors. Small published by Wiley-VCH GmbH.)

Bone metastases are a painful and complex condition that overwhelmingly impacts the prognosis and quality of life of cancer patients. Over the years, nuclear medicine has made remarkable progress in the diagnosis and management of bone metastases. This review aims to provide a comprehensive overview of the recent advancements in nuclear medicine for the diagnosis and management of bone metastases. Furthermore, the review explores the role of targeted radiopharmaceuticals in nuclear medicine for bone metastases, focusing on radiolabeled molecules that are designed to selectively target biomarkers associated with bone metastases, including osteocytes, osteoblasts, and metastatic cells. The applications of radionuclide-based therapies, such as strontium-89 (Sr-89) and radium-223 (Ra-223), are also discussed. This review also highlights the potential of theranostic approaches for bone metastases, enabling personalized treatment strategies based on individual patient characteristics. Importantly, the clinical applications and outcomes of nuclear medicine in osseous metastatic disease are discussed. This includes the assessment of treatment response, predictive and prognostic value of imaging biomarkers, and the impact of nuclear medicine on patient management and outcomes. The review identifies current challenges and future perspectives on the role of nuclear medicine in treating bone metastases. It addresses limitations in imaging resolution, radiotracer availability, radiation safety, and the need for standardized protocols. The review concludes by emphasizing the need for further research and advancements in imaging technology, radiopharmaceutical development, and integration of nuclear medicine with other treatment modalities. In summary, advancements in nuclear medicine have significantly improved the diagnosis and management of osseous metastatic disease and future developements in the integration of innovative imaging modalities, targeted radiopharmaceuticals, radionuclide production, theranostic approaches, and advanced image analysis techniques hold great promise in improving patient outcomes and enhancing personalized care for individuals with bone metastases., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2024. Published by Elsevier Inc.)

Purpose: The ADRRAD trial reported the safety and feasibility of the combination of external beam radiotherapy and radium-223 in the treatment of de novo bone metastatic prostate. This study aimed to determine if any biomarkers predictive of response to these treatments could be identified., Experimental Design: 30 patients with newly diagnosed bone metastatic hormone sensitive prostate cancer were recruited to the ADRRAD trial. Blood samples were taken pre-treatment, before cycles 2 to 6 of radium-223, and 8 weeks and 6 months after treatment. Mononuclear cells were isolated and DNA damage was assessed at all timepoints., Results: DNA damage was increased in all patients during treatment, with bigger increases in foci observed in patients who relapsed late compared to those who relapsed early. Increases in DNA damage during the radium-223 only cycles of treatment were specifically related to response in these patients. Analysis of hematology counts also showed bigger decreases in red blood cell and hemoglobin counts in patients who experienced later biochemical relapse., Conclusions: While some patients responded to this combination treatment, others relapsed within one year of treatment initiation. This study identifies a biomarker based approach that may be useful in predicting which patients will respond to treatment, by monitoring both increases in DNA damage above baseline levels in circulating lymphocytes and decreases in red blood cell and hemoglobin counts during treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Targeted alpha-particle therapy using radionuclides with alpha emission is a rapidly developing area in modern cancer treatment. To selectively deliver alpha-emitting isotopes to tumors, targeting vectors, including monoclonal antibodies, peptides, small molecule inhibitors, or other biomolecules, are attached to them, which ensures specific binding to tumor-related antigens and cell surface receptors. Although earlier studies have already demonstrated the anti-tumor potential of alpha-emitting radium (Ra) isotopes-Radium-223 and Radium-224 ( 223/224 Ra)-in the treatment of skeletal metastases, their inability to complex with target-specific moieties hindered application beyond bone targeting. To exploit the therapeutic gains of Ra across a wider spectrum of cancers, nanoparticles have recently been embraced as carriers to ensure the linkage of 223/224 Ra to target-affine vectors. Exemplified by prior findings, Ra was successfully bound to several nano/microparticles, including lanthanum phosphate, nanozeolites, barium sulfate, hydroxyapatite, calcium carbonate, gypsum, celestine, or liposomes. Despite the lengthened tumor retention and the related improvement in the radiotherapeutic effect of 223/224 Ra coupled to nanoparticles, the in vivo assessment of the radiolabeled nanoprobes is a prerequisite prior to clinical usage. For this purpose, experimental xenotransplant models of different cancers provide a well-suited scenario. Herein, we summarize the latest achievements with 223/224 Ra-doped nanoparticles and related advances in targeted alpha radiotherapy.

Background: Prostate brachytherapy (BT) techniques have evolved over the past century. This paper aimed to preserve our collective memory of history and the early development of its technique. We searched articles in PubMed and Google Scholar using keywords referring to authors, dates, and BT technical details, including different radioactive sources and country-specific publications. We reviewed the work published by Holm and Aronowitz. The digital library Internet Archives was used to retrieve original journal articles, science newspaper printings, and government reports, which allowed us to situate the development of BT in its sociopolitical context in Europe and the USA. Our search was conducted in English, French, and German languages., Summary: Early BT methods were developed by European physicians with early access to radium. Technical advancements were made by HH Young, who brought this practice to the USA, where Barringer pioneered the use of radon seeds and low-dose interstitial brachytherapy. While centralized radiotherapy centers, such as Memorial Hospital in New York, emerged for training and research, the high cost of radium and opposing interests made brachytherapy harder to implement in Germany. After World War II, the introduction of man-made radioisotopes allowed experiments with colloidal solutions and new seeds, including I-125. In the 1980s, transrectal ultrasound allowed for more accurate radioactive seed insertion and replaced the transrectal finger guidance., (© 2023 S. Karger AG, Basel.)

Introduction: Radium-223 (Ra-223) dichloride therapy increases overall survival and delays time to the first symptomatic skeletal event (SSE) in patients with castration-resistant prostate cancer (CRPC) and bone metastases. Bone-modifying agents (BMA) reduce SSE in patients with bone metastasis, but there is little information on their use with Ra-223. This study aimed to investigate the effect of BMA on SSE in patients with bone metastatic CRPC treated with Ra-223 in real-world practice., Methods: We included 73 patients treated with Ra-223 from 10 institutions in Japan. Time to the first SSE was estimated using the Kaplan-Meier method and compared between groups using the log-rank test. We used univariate analysis to ascertain the association between variables and SSE., Results: During a median follow-up of 12.7 months (interquartile range, 7-21.7), 12 (16.4%) patients presented SSE. Age and BMA use were different between men with and without SSE. The 1-year SSE-free survival rate from Ra-223 treatment initiation was 82.4% (95% CI, 69.4%-90.2%). BMA use was associated with favorable SSE-free survival (hazard risk, 0.23; 95% confidence interval, 0.061-0.85; p = 0.027). Two (4.7%) and seven (23.3%) patients presented symptomatic pathological bone fracture in groups with and without BMA use, respectively (p = 0.017)., Conclusion: This study stresses the importance of BMA use in patients with CRPC and bone metastases in Ra-223 treatment., (© 2023 The Japanese Urological Association.)

Background: Radium-223 is a bone-seeking, ɑ-emitting radionuclide used to treat men with bone metastases from castration-resistant prostate cancer. Sclerotic bone lesions cannot be evaluated using Response Evaluation Criteria in Solid Tumors. Therefore, imaging response biomarkers are needed., Methods: We conducted a phase 2 randomized trial to assess disease response to radium-223. Men with metastatic castration-resistant prostate cancer and bone metastases were randomly allocated to 55 or 88 kBq/kg radium-223 every 4 weeks for 6 cycles. Whole-body diffusion-weighted magnetic resonance imaging (DWI) was performed at baseline, at cycles 2 and 4, and after treatment. The primary endpoint was defined as a 30% increase in global median apparent diffusion coefficient., Results: Disease response on DWI was seen in 14 of 36 evaluable patients (39%; 95% confidence interval = 23% to 56%), with marked interpatient and intrapatient heterogeneity of response. There was an association between prostate-specific antigen response and MRI response (odds ratio = 18.5, 95% confidence interval = 1.32 to 258, P = .013). Mean administered activity of radium-223 per cycle was not associated with global MRI response (P = .216) but was associated with DWI response using a 5-target-lesion evaluation (P = .007). In 26 of 36 (72%) patients, new bone metastases, not present at baseline, were seen on DWI scans during radium-223 treatment., Conclusions: DWI is useful for assessment of disease response in bone. Response to radium-223 is heterogeneous, both between patients and between different metastases in the same patient. New bone metastases appear during radium-223 treatment.The REASURE trial is registered under ISRCTN17805587., (© The Author(s) 2023. Published by Oxford University Press.)

223 Ra, a targeted α-therapy, is approved for the treatment of patients with metastatic castration-resistant prostate cancer (mCRPC) who have bone metastases. In the phase 3 ALSYMPCA study, 223 Ra prolonged survival and improved quality of life versus placebo. Our real-world study, PARABO, investigated pain and bone pain-related quality of life in patients with mCRPC and symptomatic bone metastases receiving 223 Ra in clinical practice. Methods: PARABO was a prospective, observational, noninterventional single-arm study conducted in nuclear medicine centers across Germany (NCT02398526). The primary endpoint was a clinically meaningful pain response (≥2-point improvement from baseline for the worst-pain item score in the Brief Pain Inventory-Short Form). Results: The analysis included 354 patients, who received a median of 6 223 Ra injections (range, 1-6). Sixty-seven percent (236/354) received 5-6 injections, and 33% (118/354) received 1-4 injections. Of 216 patients with a baseline worst-pain score of more than 1, 59% (128) had a clinically meaningful pain response during treatment. Corresponding rates were 67% (range, 98/146) with 5-6 223 Ra injections versus 43% (range, 30/70) with 1-4 injections, 60% (range, 60/100) in patients with no more than 20 lesions versus 59% (range, 65/111) in those with more than 20 lesions, and 65% (range, 69/106) in patients without prior or concomitant opioid use versus 54% (range, 59/110) in those with prior or concomitant opioid use. Mean subscale scores (pain severity and pain interference) on the Brief Pain Inventory-Short Form improved during treatment. Conclusion: 223 Ra reduced pain in patients with mCRPC and symptomatic bone metastases, particularly in patients who received 5-6 injections. The extent of metastatic disease did not impact pain response., (© 2023 by the Society of Nuclear Medicine and Molecular Imaging.)

Background: Radium-223 (Ra-223), an α-particle-emitting isotope, inhibits bony metastases and prevents patients from skeletal-related events in metastatic castration-resistant prostate cancer (mCRPC). We retrospectively reviewed the treatment response, predictive factors, and adverse events (AEs) of Ra-223 before the National Health Insurance reimbursement in a Taiwanese tertiary institute., Methods: Patients treated with Ra-223 before January 2019 were enrolled and categorized into progressive disease (PD) and clinical benefits (CB) groups. Laboratory data before and after the treatment were collected, and spider plots concerning percentage changes of alkaline phosphatase (ALP), lactate dehydrogenase (LDH), and prostate-specific antigen (PSA) were prepared and calculated statistically. CB/PD, baseline ALP, LDH, and PSA levels were also adopted as stratification factors for overall survival (OS)., Results: Among 19 patients included, 5 (26.3%) and 14 (73.4%) belonged to the PD and CB groups, respectively, with no significant difference observed in the baseline laboratory data. The percentage changes in ALP, LDH, and PSA levels after Ra-223 treatment were statistically significant among the two groups (ALP: CB 54.3 ± 21.4% vs PD 77.6 ± 11.8%, p = 0.044; LDH: CB 88.2 ± 22.8% vs PD 138.3 ± 49.0%, p = 0.046; PSA: CB 97.8 ± 61.7% vs PD 277.0 ± 101.1%, p = 0.002). The trends of LDH between the two groups in spider plot were separated significantly. There were no differences in the AEs between the two groups. CB had a longer median OS than the PD group (20.50 months vs 9.43 months, p = 0.009). Patients with LDH <250 U/L at baseline tended to have longer OS but without significance., Conclusion: The CB rate of Ra-223 was 73.7%. No predictive factor for treatment response was obtained from pretreatment data. The mean percentage changes in ALP, LDH, and PSA levels compared with baseline significantly differed between the CB and PD groups, especially the LDH levels. The CB and PD groups showed different OS, with LDH levels exhibiting the potential to predict OS., Competing Interests: Conflicts of interest: Dr. William J. Huang, an editorial board member at the Journal of the Chinese Medical Association, had no role in the peer review process or decision to publish this article. The other authors declare that they have no conflicts of interest related to the subject matter or materials discussed in this article., (Copyright © 2023, the Chinese Medical Association.)

What Is This Summary About?: Few life-prolonging treatment options are available for patients with metastatic castration-resistant prostate cancer (mCRPC). This article provides an overview of the current systemic treatments available for mCRPC and reviews studies that investigate the optimal timing for the use of radium-223. The aim is to illustrate possible systemic treatment sequences to maximize benefit from radium-223 therapy., What Is Metastatic Castration-Resistant Prostate Cancer & How Is It Treated?: Prostate cancer is called mCRPC when it spreads to organs outside of the prostate (such as the lymph nodes, bones, liver, or lungs) and no longer responds to hormonal therapy. There are several treatment options available for mCRPC, such as abiraterone, enzalutamide, radium-223, docetaxel, cabazitaxel, olaparib, rucaparib, sipuleucel-T, and 177Lu-PSMA. It is important to understand the risks and benefits associated with each treatment and whether current use may have an impact on future treatment options, including eligibility in certain clinical trials. Maintaining bone health is also an important part of prostate cancer care., What Is Radium-223?: Radium-223 is a radioactive molecule that releases strong radiation within a very small range around itself. It mainly travels to the bone where the prostate cancer has spread and kills the cancer cells in that area. Results from a clinical study named ALSYMPCA showed that men who received radium-223 lived longer in addition to having less bone pain. The most common side effects of radium-223 are nausea, vomiting, and diarrhea. Radium-223 minimally suppresses the bone marrow, which means that it slightly reduces the levels of red and white blood cells.

Background/aim: The aim of this study was to investigate whether complete cycles of Radium-223 (Ra-223) improved survival in patients with metastatic castration resistant prostate cancer (mCRPC)., Patients and Methods: We retrospectively analyzed mCRPC patients treated with Ra-223 at Taichung Veterans General hospital. Patient and disease characteristics, laboratory results, number of bone metastases, mCRPC treatment sequence, Ra-223 treatment cycles and survival outcomes were collected. Overall survival and progression-free survival (PFS) were analyzed with Kaplan-Meier analysis. Uni- and multivariate analysis was used to identify clinical-radiologic factors that influence outcomes., Results: From October 2016 to December 2020, 42 patients with mCRPC were enrolled. Twenty-three patients received <4 cycles of Ra-223 for mCRPC and 19 patients received 5-6 cycles. The median PSA progression free survival was 2.07 months in the <4 cycles group, compared to 3.93 months in the 5-6 cycles group (log rank p=0.006). The median overall survival was 3.93 months in the <4 cycles group, compared to 28.5 months in the 5-6 cycles group (log rank p<0.001). In the multivariate model, the course number of Ra-223 and pre-treatment alkaline phosphatase (ALP) levels were independent risk factors for overall survival., Conclusion: Patients who complete 5-6 cycles of Ra-223 had significantly better overall survival than those who didn't. Patients with a lower pre-treatment ALP were more likely to benefit from Ra-223 treatment., (Copyright © 2023 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Purpose: To develop a novel nomogram for determining radium-223 dichloride (Ra-223) treatment suitability for metastatic castration-resistant prostate cancer (mCRPC) patients., Methods: This Japanese Ra-223 Therapy in Prostate Cancer using Bone Scan Index (J-RAP-BSI) Trial was a retrospective multicenter investigation enrolled 258 mCRPC patients in Japan with Ra-223 treatment between June 2016 and August 2020, with bone scintigraphy findings before treatment, clinical data, and survival outcome available. A nomogram was constructed using prognostic factors for overall survival (OS) based on a least absolute shrinkage and selection operator Cox regression model. A sub-analysis was also conducted for patients meeting European Medicines Agency (EMA) guidelines., Results: Within a median of 17.4 months after initial Ra-223 treatment, 124 patients (48.1%) died from prostate cancer. Predictive factors included (1) sum of prior treatment history (score 0, never prior novel androgen receptor-targeted agents (ARTA) therapy, never prior taxane-based chemotherapy, and ever prior bisphosphonate/denosumab treatment), (2) Eastern Cooperative Oncology Group (ECOG) performance status, (3) prostate-specific antigen doubling time (PSADT), (4) hemoglobin, (5) lactate dehydrogenase (LDH), and (6) alkaline phosphatase (ALP) levels, and (7) automated bone scan index (aBSI) value based on bone scintigraphy. The nomogram using those factors showed good discrimination, with apparent and optimism-corrected Harrell's concordance index values of 0.748 and 0.734, respectively. Time-dependent area under the curve values at 1, 2, and 3 years were 0.771, 0.818, and 0.771, respectively. In 227 patients meeting EMA recommendation, the nomogram with seven factors showed good discrimination, with apparent and optimism-corrected Harrell's concordance index values of 0.722 and 0.704, respectively. Time-dependent area under the curve values at 1, 2, and 3 years were 0.747, 0.790, and 0.759, respectively., Conclusion: This novel nomogram including aBSI to select mCRPC patients to receive Ra-223 with significantly prolonged OS possibility was found suitable for assisting therapeutic decision-making, regardless of EMA recommendation., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Radium-223 dichloride (Ra-223) is now frequently used to treat prostate cancer that has metastasized to bone, although patient selection continues to be suboptimal for determining who will benefit most from this novel treatment modality., Materials and Methods: Seventy-nine patients with metastatic castration-resistant prostate cancer (mCRPC) were treated with Ra-223 from 2012 to 2016. The burden of skeletal metastasis was determined for each using the Bone Scan Index (BSI) as a ratio of diseased to normal bone. Clinical, laboratory, and survival data were collected and examined for associations with BSI, and treatment tolerability was assessed., Results: Chemotherapy-naïve patients were significantly more likely to complete the full course of treatment. Median follow-up was 31 months (range 0.7-38.8 months) and median overall survival was 15.4 months (range 9.5-20.6 months). Overall survival was significantly associated with findings on bone scans (P < .05). Patients with higher BSI tended toward poorer outcomes. Nearly half the patients with low baseline BSI survived 3 years or more following Ra-223 treatment. By contrast, only 20% of the patients with high baseline BSI lived for 1 year, and none lived for an additional 3. Baseline BSI was significantly associated with decreased hemoglobin, higher serum PSA and alkaline phosphatase levels, and treatment-associated reductions in platelet and absolute neutrophil counts., Conclusion: Our results suggest better outcomes to Ra-223 therapy for patients who are chemotherapy-naïve and who undergo treatment earlier in the course of their disease as reflected by low BSI and concordant laboratory parameters., (© The Author(s) 2023. Published by Oxford University Press.)

The use of targeted alpha therapy (TAT) for bone cancer is increasing each year. Among the alpha radionuclides, radium [ 223 Ra]Ra +2 is the first one approved for bone cancer metastasis therapy. The development of novel radiopharmaceutical based on [ 223 Ra]Ra +2 is essential to continuously increase the arsenal of new TAT drugs. In this study we have developed, characterized, and in vitro evaluated [ 223 Ra] Ra-nano-hydroxyapatite. The results showed that [ 223 Ra] Ra-nano-hydroxyapatite has a dose-response relationship for osteosarcoma cells and a safety profile for human fibroblast cells, corroborating the application as a radiopharmaceutical., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Background: Radium-223 is a registered treatment option for symptomatic bone metastatic castration-resistant prostate cancer (mCRPC). Aim of this multicenter, prospective observational cohort study was to evaluate health-related quality of life (HR-QoL), psychological distress and fatigue in mCRPC patients treated with radium-223., Methods: Primary endpoint was cancer-specific and bone metastases-related HR-QoL, as measured by the EORTC QLQ-C30 and BM-22 questionnaires. Secondary endpoints were psychological distress and fatigue, evaluated by the HADS and CIS-Fatigue questionnaires. Outcomes were analyzed for the total cohort and between subgroups (1-3 versus 4-5 versus 6 radium-223 injections). A trajectory analysis was performed to explore HR-QoL patterns over time., Results: In total, 122 patients were included for analysis. Baseline HR-QoL, pain intensity, psychological distress and fatigue were worse in patients who did not complete radium-223 therapy. In patients who completed therapy, stabilization of HR-QoL was perceived and psychological distress and fatigue remained stable, whereas clinically meaningful and statistically significant deterioration of HR-QoL, psychological distress and fatigue over time was observed in patients who discontinued radium-223 therapy. Trajectory analysis revealed that HR-QoL deterioration over time was more likely in patients with baseline opioid use, low hemoglobin and high alkaline phosphatase levels., Conclusions: Patients who discontinued radium-223 therapy showed worse HR-QoL, psychological distress and fatigue at baseline and more frequent deterioration of HR-QoL, psychological distress and fatigue over time when compared to patients who completed therapy. Specific attention with regard to HR-QoL during follow-up is indicated in patients with opioid use, low hemoglobin and high alkaline phosphatase levels before radium-223 therapy initiation., Clinical Trial Registration Number: NCT04995614., (© 2022. The Author(s).)

Aim: Estimate the effect of Radium-223 (Ra-223) on the incidence of bone fractures, prostate cancer death, and all-cause death compared with other standard treatments for metastatic, castration-resistant prostate cancer (mCRPC)., Methods: Using a cohort design, we estimated the effect of Ra-223 on the risk of bone fractures, all-cause and prostate cancer-specific mortality across different lines of treatment for mCRPC using Prostate Cancer data Base Sweden (2013-2018). The comparator group comprised other standard treatments for mCRPC. We used 36-month risk differences and hazard ratios (HRs) as effect estimates., Results: The number of eligible individuals was 635, 453, 262, and 84 for the first-, second-, third-, and fourth-line cohorts, respectively. When compared Ra-223 to other standard treatments, the difference in the 36-month risk of fracture was 6% (95% confidence interval [CI], -7% to 18%) in the first-line cohort (n = 635) and 8% (95% CI, -7% to 18%) in the second-line cohort (n = 453). The number of fractures in the third-/fourth-line cohorts was too small for an adjusted comparison. The difference in 36-month mortality was higher in the first-line cohort 13% (95% CI, -3% to 31%), but lower in the second- and third-/fourth-line cohorts-8% (95% CI, -23% to 7%) and -14% (95% CI, -21% to 16%) respectively. Most deaths were due to prostate cancer., Conclusion: Results suggest that the difference in the risk of fractures is small, if any. A difference in the risk of mortality may be present in first-line treatment, but a decreased risk of mortality was observed in second and later lines of treatment. The results on mortality need to be considered in the context of potential unmeasured or residual confounding., (Copyright © 2022 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: The majority of radiopharmaceuticals for use in disease detection and targeted treatment undergo a single radioactive transition (decay) to reach a stable ground state. Complex emitters, which produce a series of daughter radionuclides, are emerging as novel radiopharmaceuticals. The need for validation of chemical and radiopurity with such agents using common quality control instrumentation is an area of active investigation. Here, we demonstrate novel methods to characterize 227 Th and 223 Ra. Materials and Methods: A radio-TLC scanner and a γ-counter, two common and widely accessible technologies, as well as a solid-state α-particle spectral imaging camera were evaluated for their ability to characterize and distinguish 227 Th and 223 Ra. We verified these results through purity evaluation of a novel 227 Th-labeled protein construct. Results: The γ-counter and α-camera distinguished 227 Th from 223 Ra, enabling rapid and quantitative determination of radionuclidic purity. The radio-TLC showed limited ability to describe purity, although use under α-particle-specific settings enhanced resolution. All three methods were able to distinguish a pure from impure 227 Th-labeled protein. Conclusions: The presented quality control evaluation for 227 Th and 223 Ra on three different instruments can be applied to both research and clinical settings as new alpha particle therapies are developed.

The use of alpha-particle (α-particle) radionuclides, especially [ 223 Ra]RaCl 2 (radium dichloride), for targeted alpha therapy is steadily increasing. Despite the positive clinical outcomes of this therapy, very little data are available about the effect on the ultrastructure of cells. The purpose of this study was to evaluate the nanomechanical and ultrastructure effect of [ 223 Ra] RaCl 2 on cancer cells. To analyze the effect of [ 223 Ra]RaCl 2 on tumor cells, human breast cancer cells (lineage MDA-MB-231) were cultured and treated with the radiopharmaceutical at doses of 2 µCi and 0.9 µCi. The effect was evaluated using atomic force microscopy (AFM) and transmission electron microscopy (TEM) combined with Raman spectroscopy. The results showed massive destruction of the cell membrane but preservation of the nucleus membrane. No evidence of DNA alteration was observed. The data demonstrated the formation of lysosomes and phagosomes. These findings help elucidate the main mechanism involved in cell death during α-particle therapy.

Radium-223 dichloride and enzalutamide are indicated for metastatic castration-resistant prostate cancer and their combination is currently being investigated in a large phase 3 clinical trial. Here, we evaluated the antitumor efficacy of radium-223, enzalutamide, and their combination in the intratibial LNCaP model mimicking prostate cancer metastasized to bone. In vitro experiments revealed that the combination of radium-223 and enzalutamide inhibited LNCaP cell proliferation and showed synergistic efficacy. The combination of radium-223 and enzalutamide also demonstrated enhanced in vivo antitumor efficacy, as determined by measuring serum PSA levels in the intratibial LNCaP model. A decreasing trend in the total area of tumor-induced abnormal bone was associated with the combination treatment. The serum levels of the bone formation marker PINP and the bone resorption marker CTX-I were lowest in the combination treatment group and markedly decreased compared with vehicle group. Concurrent administration of enzalutamide did not impair radium-223 uptake in tumor-bearing bone or the ability of radium-223 to inhibit tumor-induced abnormal bone formation. In conclusion, combination treatment with radium-223 and enzalutamide demonstrated enhanced antitumor efficacy without compromising the integrity of healthy bone. The results support the ongoing phase 3 trial of this combination.

Despite extensive treatment with surgery and chemotherapy many patients with peritoneal metastases from colorectal cancer experience intraperitoneal disease relapse. The α-emitting 224 radium-labelled microparticle radionuclide therapeutic Radspherin® is being explored as a novel treatment option for these patients. Radspherin® is specially designed to give local radiation to the surface of the peritoneal cavity and potentially kill remaining attached micrometastases as well as free-floating cancer cells, thus preventing future relapse. The effect of Radspherin® on the immune system is not known. Systemic and local inflammatory responses were analyzed in plasma, intraperitoneal fluid and urine collected prospectively as part of a phase 1 dose-escalation study of intraperitoneal instillation of the α-emitting therapeutic radiopharmaceutical Radspherin®, at baseline and the first 7 postoperative days from nine patients undergoing cytoreductive surgery and hyperthermic intraperitoneal chemotherapy. All patients additionally received intraperitoneal instillation of Radspherin® on postoperative day 2. Complement activation products C3bc and the terminal complement complex were analyzed using enzyme-linked immunosorbent assay. Cytokines ( n  = 27), including interleukins, chemokines, interferons and growth factors, were analyzed using multiplex technique. The time course and magnitude of the postoperative cytokine response after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy displayed a modest systemic response in plasma, in contrast to a substantial local intraperitoneal response. After administration of Radspherin®, a significant increase ( P  < 0.05) in TNF and MIP-1β was observed in both plasma and peritoneal fluid, whereas IL-9 increased only in plasma and IFNγ and IL1-RA only in peritoneal fluid. Only minor changes were seen for the majority of the inflammatory markers after Radspherin® administration. Our study showed a predominately local rather than systemic inflammatory response to cytoreductive surgery and hyperthermic intraperitoneal chemotherapy. Radspherin® had overall modest impact on the inflammation.

Background: Uterine clear cell and serous carcinomas have a high propensity for locoregional and distant spread, tend to be more advanced at presentation, and carry a higher risk of recurrence and death than endometrioid cancers. Limited prospective data exist to guide evidence-based management of these rare malignancies., Objective: The American Radium Society sought to summarize evidence-based guidelines developed by a multidisciplinary expert panel that help to guide the management of uterine clear cell and serous carcinomas., Methods: The American Radium Society Appropriate Use Criteria presented in this manuscript were developed by a multidisciplinary expert panel using an extensive analysis of current published literature from peer-reviewed journals. A well-established methodology (modified Delphi) was used to rate the appropriate use of diagnostic and therapeutic procedures for the management of uterine clear cell and serous carcinomas., Results: The primary treatment for non-metastatic uterine clear cell and serous carcinomas is complete surgical staging, with total hysterectomy, salpingo-oophorectomy, omentectomy, and lymph node staging. Even in early-stage disease, patients with uterine clear cell and serous carcinomas have a worse prognosis than those with type I endometrial cancers, warranting consideration for adjuvant therapy regardless of the stage. Given the aggressive nature of these malignancies, and until further research determines the most appropriate adjuvant therapy, it may be reasonable to counsel patients about combined-modality treatment with systemic chemotherapy and radiotherapy., Conclusion: Patients diagnosed with uterine clear cell and serous carcinomas should undergo complete surgical staging. Multimodal adjuvant therapies should be considered in the treatment of both early-stage and advanced-stage disease. Further prospective studies or multi-institutional retrospective studies are warranted to determine optimal sequencing of therapy and appropriate management of patients based on their unique risk factors. Long-term surveillance is indicated due to the high risk of locoregional and distant recurrence., Competing Interests: Competing interests: All panelists were required to declare all conflicts of interest for the previous 36 months prior to initiating work on this document. These complete disclosure forms are retained by the American Radium Society (ARS) in perpetuity. The ARS Appropriate Use Criteria Steering Committee reviewed these disclosures with the chair and co-chair of this document and approved participation of the panelists prior to starting development of this work. Disclosures potentially relevant to the content of this guideline are provided. List of any potentially relevant conflicts of interest for the past 3 years for guideline chair, guideline co-chair, all voting and non-voting panelists: MB: consulting fee/honoraria (Elekta, Inc.). DG: consulting fee/honoraria (AstraZeneca, Merck). RLC: grants for clinical trials (NIH, Gateway Foundation, V-Foundation, Judy Rees/Albert Pisani MD Ovarian Cancer Research Fund, AstraZeneca, Merck, Clovis, Genmab, Roche/Genentech, Janssen); consulting fee/honoraria (AstraZeneca, Tesaro, Medivation, Clovis, Gamamab, Genmab, Roche/Genentech, Janssen, Agenus, Regeneron, OncoQuest). MH: consulting fee/Honoraria (Varian Brachytherapy; AstraZeneca). SJ: consulting fee/honoraria (AstraZeneca, Varian). WS, Jr: consulting fee/honoraria (Merck, Carl Zeiss, Varian)., (© IGCS and ESGO 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

The oldest form of radiation therapy, brachytherapy, has been investigated and reported in the scientific and medical literature for well over a century. Known by many names over the years, radium-based, empirical practices evolved over decades to contemporary practice. This includes treatment at various dose rates using multiple radionuclides or even electrically generated photon sources. Predictions or prognostications of what may happen in the future enjoy a history that spans centuries, e.g. those by Nostradamus in the 1500s. In this review article, publications from several eras of past practice between the early 1900s and the late 2010s where the authors address the "future of brachytherapy" are presented, and for many of these publications, one can use the benefit of the intervening years to comment on the accuracy or the inaccuracies inherent in those publications. Finally, recently published papers are reviewed to examine current expectations for the future practice of brachytherapy.

The scope of scientific literature was reviewed to summarize the data on the 223Radichloride therapy for castration resistant forms of prostate cancer. Key advantages of the alphaemitters over betaemitting radionuclides are highlighted in the treatment of hormoneresistant bone metastases. Data demonstrating an association between the 223Radichloride treatment effectiveness and absorbed therapeutic doses were analyzed. Dependence between the 223Ra and 18Ffluoride absorbed doses in bone metastases was evaluated, which should be taken into account in a positron emission tomography monitoring. Results of studies examining the uptake of 18Ffluoride to predict the 223Radichloride accumulation during the first course of treatment were analyzed. Research areas requiring further concern have been identified through the literature review, namely: study of the relationship between an absorbed dose and other clinically relevant endpoints, including pain index, changes in alkaline phosphatase or prostate antigen levels, survival rates, and development of alternative treatment regimens depending on the therapeutic radiopharmaceutical dose.

Background: Our study aims to identify baseline prognostic factors in metastatic castration resistant prostate cancer (mCRPC) patients treated with radium-223., Methods: Data about demographics, ECOG performance status, lymph node (LN) involvement, local treatment for prostate cancer, previous systemic treatments, cells blood count, PSA, ALP, albumin, LDH, bone protecting agents use (BPA), analgesic use and survival were collected. Univariable and multivariable analyses were performed., Results: Seventy-five men received radium-223 between September 2013 and December 2019. Median age was 73 years. Thirty-four (45.3%) had ECOG PS 0, 41 (54.7%) PS 1-2. In univariable analysis, LN involvement (HR 1.68, 95% CI 1.01-2.80, P=0.047), absence of local treatment on primary tumor (HR 1.93, 95% CI 1.13-3.29, P=0.016), baseline strong opioidsuse (HR 1.82, 95% CI 1.08-3.06, P=0.024), high platelets to lymphocyte ratio (PLR) (HR 1.91, 95% CI 1.06-3.45, P=0.03), high baseline ALP (HR 1.81, 95% CI 1.10-2.99, P=0.019) and high baseline LDH (HR 3.86,95% CI 2.01-7.41, P<0.001) were significantly associated with worst OS. At multivariable analysis, LN involvement, strong opioids use, baseline ALP, LDH and PLR levels were significantly associated with outcome., Conclusions: In mCRPC patients treated with Radium-223, baseline ALP, LDH, strong opioid use, PLR, LN involvement and treatment on primary site are associated with different OS.

Radium-223 dichloride ( 223 RaCl2), approved by FDA (Food and Drug Administration) in 2013 and in Brazil by ANVISA (Agência Nacional de Vigilância Sanitária) in 2016, offers a new therapeutic option for bone metastases from castration-resistant prostate cancer (CRPC). The advantages of radionuclide therapy for bone metastases include the simultaneous treatment of multiple lesions at the same time. The activity prescription is based on the patient's body weight, disregarding the absorbed dose limit of 2 Gy in the organ at risk: bone marrow. This study focuses on Internal Dosimetry for 223 RaCl2 therapy aiming to apply biokinetic models described in the literature to estimate absorbed doses in the organs of interests, especially for the bone marrow. For this purpose, the present paper compares and validates the GATE Monte Carlo simulation with the Radioactive Decay Module (RDM) and calculates a set of S-values for Radium-223 radionuclide using male and female XCAT computational models. Moreover, a comparison of S-values for Radium-223 for three male computational models with different anatomies is also evaluated, Male (standard), Pat1 (lower body weight) and Pat2 (highest body weight). A comprehensive set of S-values was calculated for the Male model, 30 source-regions and 47 target-regions, and for Female model, 30 source-regions and 42 target-regions for Radium-223 and its decay scheme: Radon-219, Polonium-215, Lead-211, Bismuth- 211, Polonium-211 and Thallium-207. The new set of S-values will facilitate absorbed dose calculations for Radium-223 therapy. In addition, Absorbed Dose Evaluation for 223 RaCl2 therapy was estimated for three different biodistributions described in the literature within three male computational models. For all biodistributions, the Pat2 phantom has a greatest absorbed dose within the red marrow, when compared with Male and Pat1., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Catherine C O Silva reports financial support was provided by CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Background: Radium-223 is an alpha-emitting, bone-targeting radiopharmaceutical that confers a survival benefit in patients with confirmed bone-metastatic, castration-resistant prostate cancer with no visceral metastases. We studied real-world use of radium-223 in eligible patients from a tertiary hospital., Methods: We retrospectively collected clinical data of patients treated with radium-223 in Tungs' Taichung MetroHarbor Hospital by chart review. Data included biochemical parameters, pain scores, other prostate cancer treatments received and adverse events (AEs)., Results: Of 36 patients included in the study, 12 patients received radium-223 as first-line therapy, 11 as second-line treatment and 13 as third-line treatment. Prostate-specific antigen significantly increased from baseline in patients who received radium-223 as third-line treatment and in patients who received radium-223 post-chemotherapy. Pain scores significantly decreased when radium-223 was given as second-line and as third-line treatment. In the patients who were naive to novel anti-hormone (NAH) therapy and chemotherapy, mean alkaline phosphatase level significantly decreased from baseline. The most common AE was anemia, found in 16.7% of patients., Conclusion: Radium-223 had early biochemical benefits, while in the later stages of the disease, it reduced bone pain in this real-world cohort of chemotherapy-naive, NAH-naive patients, and patients with prior therapy, from a tertiary institution in Taiwan., Competing Interests: Declaration of competing interest The authors have no conflicts of interest relevant to this article., (Copyright © 2022 Formosan Medical Association. Published by Elsevier B.V. All rights reserved.)

Background: The phase 3 trial ERA223 demonstrated an increased fracture rate and no survival advantage for metastatic castration resistant prostate cancer (mCRPC) patients on Radium-223 (Ra-223) with abiraterone, leading to regulatory restrictions on combination therapy. However, less than half of trial patients received bone health agents (BHA). We reviewed electronic health record (EHR) data evaluating fracture rates for patients on BHA receiving Ra-223, androgen deprivation therapy and either abiraterone or enzalutamide., Patients and Methods: We conducted a retrospective, cohort analysis of EHR data of mCRPC patients on Ra-223 treated at a single community center by a single provider between 2010 and 2018. The primary objective was evaluating fracture rates for patients on BHA receiving Ra-223 and abiraterone. We conducted a secondary analysis for enzalutamide., Results: One hundred seventy-seven patients received Ra-223 concurrently with abiraterone or enzalutamide between November 2010 and August 2018. The median age was 73 at first Ra-223 dose (range 40-93). The median follow-up time from last Ra-223 dose was 30 months (range 2-106). One hundred sixty-four patients (93%) received BHAs. One hundred fifty-nine patients (89%) were on a BHA before and/or during Ra-223. Sixty-seven patients received denosumab (38%), 63 received zoledronic acid (36%), and 29 received both nonconcurrently (16%). Eleven patients (6.2%) experienced a fracture after starting Ra-223, 9 of which occurred while on prior and/or concurrent BHA. We observed a 5.7% fracture rate for mCRPC patients who received combination therapy and denosumab or zoledronic acid., Conclusion: This real-world analysis demonstrating a low fracture rate in patients with mCRPC receiving a BHA while on Ra-223 and abiraterone or enzalutamide may inform current clinical practice., (Copyright © 2022. Published by Elsevier Inc.)

Background: Radium (Ra)-223 is an established treatment option for patients with metastatic castrate-resistant prostate cancer (mCRPC) who have symptomatic bone metastases without soft tissue disease. Studies have indicated genetic aberrations that regulate DNA damage response (DDR) in prostate cancer can increase susceptibility to treatments such as poly ADP-ribose polymerase inhibitors and platinum-based therapies. This study aims to evaluate mCRPC response to Ra-223 stratified by tumor genomics., Methods: This is a retrospective study of mCRPC patients who received Ra-223 and genetic testing within the Mayo Clinic database (Arizona, Florida, and Minnesota) and Tulane Cancer Center. Patient demographics, genetic aberrations, treatment responses in terms of alkaline phosphatase (ALP) and prostate-specific antigen (PSA), and survival were assessed. Primary end points were ALP and PSA response. Secondary end points were progression-free survival (PFS) and overall survival (OS) from time of first radium treatment., Results: One hundred and twenty-seven mCRPC patients treated with Ra-223 had germline and/or somatic genetic sequencing. The median age at time of diagnosis and Ra-223 treatment was 61.0 and 68.6 years, respectively. Seventy-nine (62.2%) had Gleason score ≥ 8 at time of diagnosis. 50.4% received prior docetaxel, and 12.6% received prior cabazitaxel. Notable alterations include TP53 (51.7%), BRCA 1/2 (15.0%), PTEN (13.4%), ATM (11.7%), TMPRSS2-ERG (8.2%), RB deletion (3.4%), and CDK12 (1.9%). There was no significant difference in ALP or PSA response among the different genetic aberrations. Patients with a TMPRSS2-ERG mutation exhibited a trend toward lower OS 15.4 months (95% confidence interval [CI] 10.0-NR) versus 26.8 months (95% CI 20.9-35.1). Patients with an RB deletion had a lower PFS 6.0 months (95% CI 1.28-NR) versus 9.0 months (95% CI 7.3-11.1) and a lower OS 13.9 months (95% CI 5.2-NR) versus 26.5 months (95% CI 19.8-33.8)., Conclusions: Among mCRPC patients treated with Ra-223 at Mayo Clinic and Tulane Cancer Center, we did not find any clear negative predictors of biochemical response or survival to treatment. TMPRSS2-ERG and RB mutations were associated with a worse OS. Prospective studies and larger sample sizes are needed to determine the impact of genetic aberrations in response to Ra-223., (© 2022 Wiley Periodicals LLC.)

Objective: The objective of this study was to systematically evaluate the data regarding the use of neoadjuvant, perioperative, surgical, and adjuvant treatment options in localized gastric cancer patients and to develop Appropriate Use Criteria recommended by a panel of experts convened by the American Radium Society., Methods: Preferred reporting items for systematic reviews and meta-analyses methodology was used to develop an extensive analysis of peer-reviewed phase 2/2R/3 trials, as well as meta-analyses found within the Ovid Medline database between 2010 and 2020. The expert panel then rated the appropriateness of various treatments in 5 representative clinical scenarios through a well-established consensus methodology (modified Delphi)., Results: For patients with medically operable locally advanced gastric cancer, the strongest recommendation was for perioperative chemotherapy based on high-quality data. Acceptable alternatives included surgery followed by either chemotherapy or concurrent chemoradiotherapy (CRT). For patients with upfront resection of stages I to III gastric cancer (no neoadjuvant therapy), the group strongly recommended adjuvant therapy with either chemotherapy alone or CRT, based on high-quality data. For patients with locally advanced disease who received preoperative chemotherapy without tumor regression, the group strongly recommended postoperative chemotherapy or postoperative CRT. Finally, for medically inoperable gastric cancer patients, there was moderate consensus recommending definitive concurrent CRT., Conclusions: The addition of chemotherapy and/or radiation, either in the neoadjuvant, adjuvant, or perioperative setting, results in improved survival rates for patients compared with surgery alone. For inoperable patients, definitive CRT is a reasonable treatment option, though largely palliative., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Background: The ALSYMPCA trial revealed radium-223 (Ra-223) to be a life-prolonging agent for bone metastatic castration-resistant prostate cancer (CRPC). However, only 2.8% of enrolled patients in that clinical trial were Asian, and no Japanese patients were enrolled. Several retrospective studies have been published concerning Japanese bone metastatic CRPC patients receiving Ra-223. However, no study has yet reported the correlation between Ra-223 induction and the survival in Japanese bone metastatic CRPC patients. This study investigated the effect of Ra-223 as a life-prolonging agent in a large Japanese healthcare fee database., Methods: A total of around 410 000 prostate cancer patients were extracted from this database, and 25 934 were diagnosed with CRPC. In these patients, the age, date of the CRPC diagnosis, date of Ra-223 induction, and prognosis were analyzed., Results: A total of 1628 patients received Ra-223, and 6693 patients were diagnosed with bone metastasis CRPC, with the remaining 17 613 patients diagnosed with CRPC without bone metastasis. The patients who completed six courses of Ra-223 showed a significantly more favorable overall and cancer-specific survival than those who received ≤5 courses (p < 0.0001 and p < 0.0001, respectively). For time from CRPC diagnosis date to death, the Ra-223 induction group showed a significantly more favorable prognosis with regard to both the overall and cancer-specific survival than the bone metastatic CRPC patients without Ra-223 (p < 0.0001 and p < 0.0001, respectively)., Conclusions: Bone metastatic CRPC patients who received Ra-223 showed a significantly better prognosis than bone metastatic CPRC patients who did not receive Ra-223., (© 2022 The Authors. International Journal of Urology published by John Wiley & Sons Australia, Ltd on behalf of The Japanese Urological Association.)

Retreatment of recurrent or second primary head and neck cancers occurring in a previously irradiated field is complex. Few guidelines exist to support practice. We performed an updated literature search of peer-reviewed journals in a systematic fashion. Search terms, key questions, and associated clinical case variants were formed by panel consensus. The literature search informed the committee during a blinded vote on the appropriateness of treatment options via the modified Delphi method. The final number of citations retained for review was 274. These informed 5 key questions, which focused on patient selection, adjuvant reirradiation, definitive reirradiation, stereotactic body radiation, and reirradiation to treat nonsquamous cancer. Results of the consensus voting are presented along with discussion of the most current evidence. This provides updated evidence-based recommendations and guidelines for the retreatment of recurrent or second primary cancer of the head and neck., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Prostate cancer is a significant cause of morbidity and mortality among men worldwide. Although most patients present with localized or regional disease and experience excellent outcomes with treatment, approximately 10% to 20% of patients develop castrate-resistant prostate cancer (CRPC) within 5 years of diagnosis. Bone metastases, which can cause pain and adversely affect quality of life, are common among this population. Radium-223 has a relatively short half-life and decays via α-decay. Its daughter products, α-particles, have a short path length in tissue and exhibit high linear energy transfer. Together, these properties allow radium-223 to achieve relatively high cell kill in its target tissue while sparing the surrounding normal tissues. Administered in the clinic as radium-223 dichloride (Xofigo), radium-223 acts as a calcium mimetic in the human body, forming complexes with hydroxyapatite. In areas of high bone turnover, such as the osteoblastic bone metastases that are common in patients with CRPC, radium-223 is preferentially incorporated into the bone matrix, where it can exert an antitumor effect. In May 2013, the U.S. Food and Drug Administration approved Xofigo for use in patients with CRPC who have symptomatic bone metastases and no visceral metastases. In this topic discussion, we review the mechanism of action and clinical efficacy of radium-223 in patients with metastatic CRPC. We also discuss its administration and handling, distribution and elimination, and associated toxicities., (Copyright © 2022. Published by Elsevier Inc.)