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Osteoclast inhibitors to prevent bone metastases in men with high-risk, non-metastatic prostate cancer: A systematic review and meta-analysis.

ABSTRACT: In advanced prostate cancer, osteoclast inhibitors prevent and palliate skeletal related events associated with bone metastases. However, it is uncertain whether they play a disease-modifying role earlier in the course of the disease.Medline, EMBASE, Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Reviews and ASCO conference proceedings were searched for randomized controlled trials that compared osteoclast inhibitors with placebo and/or standard of care (SOC) in patients with high-risk, non-metastatic prostate cancer. The primary outcome measure was incidence of new bone metastases; secondary outcomes included overall survival (OS), prostate cancer specific survival, mortality unrelated to prostate cancer, toxicity and health related quality of life outcomes. Results are presented as relative risk (RR) with 95% confidence intervals (CI).Six randomized controlled trials (5947 participants) were included, five evaluating bisphosphonates and one denosumab. Overall, there was no difference in incidence of bone metastases between participants treated with osteoclast inhibitors versus placebo/SOC (RR 1.09, 95%CI 0.84-1.41, p = 0.51) however significant heterogeneity was observed between studies. The denosumab trial was the largest and only positive trial amongst the included studies (RR 0.83, 95%CI 0.73-0.95, p = 0.007). No significant difference was observed in OS (RR 0.99 95% CI 0.89-1.10, p = 0.84) nor prostate cancer specific survival (RR 1.12 95%CI 0.93-1.36, p = 0.24). Most studies reported increased rates of osteonecrosis of the jaw (5% or less) and hypocalcemia (2% or less) with osteoclast inhibitors.While there is limited evidence that bisphosphonates alter the natural history of high-risk, non-metastatic prostate cancer, denosumab delays onset of bone metastases in this patient population. Neither class of osteoclast inhibitor demonstrated an impact on survival outcomes. Future trials with better defined patient selection and a robust definition for high risk disease is critical.

SUBMITTER: Hayes AR

PROVIDER: S-EPMC5784941 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BACKGROUND:Whole-body assessments of 18F-NaF positron emission tomography (PET)/computed tomography (CT) provide promising quantitative imaging biomarkers of metastatic castration-resistant prostate cancer (mCRPC). This study investigated whether the distribution of metastases across anatomic regions is prognostic of progression-free survival. PATIENTS AND METHODS:Fifty-four mCRPC patients with osseous metastases received baseline NaF PET/CT. Patients received chemotherapy (n = 16) or androgen receptor pathway inhibitors (n = 38). Semiautomated analysis using Quantitative Total Bone Imaging software extracted imaging metrics for the whole, axial, and appendicular skeleton as well as 11 skeletal regions. Five PET metrics were extracted for each region: number of lesions (NL), standardized maximum uptake value (SUVmax), average uptake (SUVmean), sum of uptake (SUVtotal), and diseased fraction of the skeleton (volume fraction). Progression included that discovered by clinical, biochemical, or radiographic means. Univariate and multivariate Cox proportional hazard regression analyses were performed between imaging metrics and progression-free survival, and were assessed according to their hazard ratios (HR) and concordance (C)-indices. RESULTS:The strongest univariate models of progression-free survival were pelvic NL and SUVmax with HR = 1.80 (NL: false discovery rate adjusted P = .001, SUVmax: adjusted P = .001). Three other region-specific metrics (axial NL: HR = 1.59, adjusted P = .02, axial SUVmax: HR = 1.61, adjusted P = .02, and skull SUVmax: HR = 1.58, adjusted P = .04) were found to be stronger prognosticators relative to their whole-body counterparts. Multivariate model including region-specific metrics (C-index = 0.727) outperformed that of whole-body metrics (C-index = 0.705). The best performance was obtained when region-specific and whole-body metrics were included (C-index = 0.742). CONCLUSION:Quantitative characterization of metastatic spread by anatomic location on NaF PET/CT enhances potential prognostication. Further study is warranted to optimize the prognostic and predictive value of NaF PET/CT in mCRPC patients.

Project description:BackgroundRadium-223 is a targeted alpha-particle therapy that improves survival in men with metastatic castration resistant prostate cancer (mCRPC), particularly in men with elevated serum levels of bone alkaline phosphatase (B-ALP). We hypothesized that osteomimicry, a form of epithelial plasticity leading to an osteoblastic phenotype, may contribute to intralesional deposition of radium-223 and subsequent irradiation of the tumor microenvironment.MethodsWe conducted a pharmacodynamic study (NCT02204943) of radium-223 in men with bone mCRPC. Prior to and three and six months after radium-223 treatment initiation, we collected CTCs and metastatic biopsies for phenotypic characterization and CTC genomic analysis. The primary objective was to describe the impact of radium-223 on the prevalence of CTC B-ALP over time. We measured radium-223 decay products in tumor and surrounding normal bone during treatment. We validated genomic findings in a separate independent study of men with bone metastatic mCRPC (n = 45) and publicly accessible data of metastatic CRPC tissues.ResultsWe enrolled 20 men with symptomatic bone predominant mCRPC and treated with radium-223. We observed greater radium-223 radioactivity levels in metastatic bone tumor containing biopsies compared with adjacent normal bone. We found evidence of persistent Cellsearch CTCs and B-ALP (+) CTCs in the majority of men over time during radium-223 therapy despite serum B-ALP normalization. We identified genomic gains in osteoblast mimicry genes including gains of ALPL, osteopontin, SPARC, OB-cadherin and loss of RUNX2, and validated genomic alterations or increased expression at the DNA and RNA level in an independent cohort of 45 men with bone-metastatic CRPC and in 150 metastatic biopsies from men with mCRPC.ConclusionsOsteomimicry may contribute in part to the uptake of radium-223 within bone metastases and may thereby enhance the therapeutic benefit of this bone targeting radiotherapy.

Project description:ImportanceBoth α-emitting and β-emitting bone-targeted radioisotopes (RIs) have been developed to treat men with metastatic castration-resistant prostate cancer (CRPC). Only 1 phase 3 randomized clinical trial has demonstrated an overall survival (OS) benefit from an α-emitting RI, radium 223 (223Ra), vs standard of care. Yet no head-to-head comparison has been done between α-emitting and β-emitting RIs.ObjectiveTo assess OS in men with bone metastases from CRPC treated with bone-targeted RIs and to compare the effects of α-emitting RIs with β-emitting RIs.Data sourcesPubMed, Cochrane Library, ClinicalTrials.gov, and meeting proceedings between January 1993 and June 2013 were reviewed. Key terms included randomized trials, radioisotopes, radiopharmaceuticals, and prostate cancer. Data were collected, checked, and analyzed from February 2017 to October 2018.Study selectionSelected trials included patients with prostate cancer, recruited more than 50 patients from January 1993 to June 2013, compared RI use with no RI use (placebo, external radiotherapy, or chemotherapy), and were randomized. Patients were diagnosed with histologically proven prostate cancer and disease progression after both surgical or chemical castration and have evidence of bone metastasis. Nine randomized clinical trials were identified as eligible, but 3 were excluded for insufficient data.Data extraction and synthesisIndividual patient data were requested for each eligible trial, and all data were checked with a standard procedure. The log-rank test stratified by trial was used to estimate hazard ratios (HRs), and a similar fixed-effects (FE) model was used to estimate odds ratios (ORs). The between-trial heterogeneity of treatment effects was evaluated by Cochran test and I2 and was accounted by a random-effects (RE) model.Main outcomes and measuresOverall survival; secondary outcomes were symptomatic skeletal event (SSE)-free survival and adverse events.ResultsBased on 6 randomized clinical trials including 2081 patients, RI use was significantly associated with OS compared with no RI use (HR, 0.86; 95% CI, 0.77-0.95; P = .004) with high heterogeneity (χ25 = 24.46; P < .001; I2 = 80%), but this association disappeared when using an RE model (HR, 0.80; 95% CI, 0.61-1.06; P = .12; τ2 = 0.08). The heterogeneity is explained both by the type of RI and by the inclusion of 2 outlier trials that included 275 patients; the OS benefit was significantly higher with the α-emitting RI 223Ra (HR, 0.70; 95% CI, 0.58-0.83) but not significant with the β-emitting RI strontium-89 (HR, 0.96; 95% CI, 0.84-1.10) (P for interaction = .004). Excluding the outlier trials led to an overall HR of 0.82 (95% CI, 0.73-0.92; P < .001) (between-trial heterogeneity: χ23 = 6.51; P = .09; I2 = 54%) using an FE model and an HR of 0.80 (95% CI, 0.65-0.99; P = .04; τ2 = 0.02) using an RE model. The HR for SSE-free survival was 0.81 (95% CI, 0.69-0.93; P = .004) (between-trial heterogeneity: χ23 = 6.71; P = .08; I2 = 55%) when using an FE model and was 0.76 (95% CI, 0.58-1.01; P = .06; τ2 = 0.04) when using an RE model. There were more hematological toxic effects with RI use compared with no RI use (OR, 1.48; 95% CI, 1.17-1.88; P = .001).Conclusions and relevanceIn metastatic CRPC, a significant improvement of OS and SSE-free survival was obtained with bone-targeted α-emitting but not β-emitting RIs. Caution is necessary for generalizability of these results, given the between-trial heterogeneity.

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Osteoclast inhibitors to prevent bone metastases in men with high-risk, non-metastatic prostate cancer: A systematic review and meta-analysis.

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