Clinical Correlates of Benefit From Radium-223 Therapy in Metastatic Castration Resistant Prostate Cancer

Predictive and Prognostic 18F-Fluorocholine PET/CT Radiomics Nomogram in Patients with Castration-Resistant Prostate Cancer with Bone Metastases Treated with 223Ra

PURPOSE

We aimed to develop a nomogram able to predict treatment failure, skeletal events, and overall survival (OS) in patients with castration-resistant prostate cancer with bone metastases (CRPC-BM) treated with Radium-223 dichloride (223Ra).

PATIENTS AND METHODS

Patients from the Castilla-La Mancha Spanish region were prospectively included in the ChoPET-Rad multicenter study from January 2015 to December 2022. Patients underwent baseline, interim, and end-of-treatment bone scintigraphy (BS) and 18F-Fluorocholine PET/CT (FCH PET/CT) scans, obtaining multiple imaging radiomics as well as clinical and biochemical variables during follow-up and studying their association with the previously defined end-points. Survival analysis was performed using the Kaplan-Meier method and Cox regression. Multivariate logistic and Cox regression models were calculated, and these models were depicted by means of nomograms.

RESULTS

Median progression-free survival (PFS) and OS were 4 and 14 months (mo), respectively. The variables that showed independent and significant association with therapeutic failure were baseline alkaline phosphatase (AP) levels (p = 0.022) and the characteristics of BM on the CT portion of PET/CT (p = 0.017). In the case of OS, the significant variables were therapeutic failure (p = 0.038), the number of lines received after 223Ra (p < 0.001), average SUVmax (p = 0.002), bone marrow infiltration in FCH PET/CT (p = 0.006), and interim FCH PET/CT response (p = 0.048). Final nomograms included these variables, showing good discrimination among the 100 patients included in our study. In the study of skeletal events, only OS showed a significant association in the multivariate analysis, resulting in an inconsistent nomogram design.

CONCLUSIONS

FCH PET/CT appears to be a good tool for evaluating patients eligible for treatment with 223Ra, as well as for their follow-up. Thus, findings derived from it, such as the morphological characteristics of BM in the CT, bone marrow infiltration, or the response to 223Ra in the interim study, have proven to be solid and useful variables in the creation of nomograms for predicting therapeutic failure and OS.

Assessing Therapeutic Response to Radium-223 with an Automated Bone Scan Index among Metastatic Castration-Resistant Prostate Cancer Patients: Data from Patients in the J-RAP-BSI Trial

To evaluate the usefulness of change in the automated bone scan index (aBSI) value derived from bone scintigraphy findings as an imaging biomarker for the assessment of treatment response and survival prediction in metastatic castration-resistant prostate cancer (mCRPC) patients treated with Ra-223. This study was a retrospective investigation of a Japanese cohort of 205 mCRPC patients who received Ra-223 in 14 hospitals between July 2016 and August 2020 and for whom bone scintigraphy before and after radium-223 treatment was available. Correlations of aBSI change, with changes in the serum markers alkaline phosphatase (ALP) and prostate-specific antigen (PSA) were evaluated. Additionally, the association of those changes with overall survival (OS) was assessed using the Cox proportional-hazards model and Kaplan-Meier curve results. Of the 205 patients enrolled, 165 (80.5%) completed six cycles of Ra-223. Following treatment, ALP decline (%ALP < 0%) was noted in 72.2% (148/205), aBSI decline (%aBSI < 0%) in 52.7% (108/205), and PSA decline (%PSA < 0%) in 27.8% (57/205). Furthermore, a reduction in both aBSI and ALP was seen in 87 (42.4%), a reduction in only ALP was seen in 61 (29.8%), a reduction in only aBSI was seen in 21 (10.2%), and in both aBSI and ALP increasing/stable (≥0%) was seen in 36 (17.6%) patients. Multiparametric analysis showed changes in PSA [hazard ratio (HR) 4.30, 95% confidence interval (CI) 2.32-8.77, p < 0.0001], aBSI (HR 2.22, 95%CI 1.43-3.59, p = 0.0003), and ALP (HR 2.06, 95%CI 1.35-3.14, p = 0.0008) as significant prognostic factors for OS. For mCRPC patients treated with Ra-223, aBSI change is useful as an imaging biomarker for treatment response assessment and survival prediction.

Novel nomogram developed for determining suitability of metastatic castration-resistant prostate cancer patients to receive maximum benefit from radium-223 dichloride treatment-Japanese Ra-223 Therapy in Prostate Cancer using Bone Scan Index (J-RAP-BSI) Trial

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.

Optimization of Radium-223 Treatment of Castration-resistant Prostate Cancer Based on the Burden of Skeletal Metastasis and Clinical Parameters

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.

223Ra Induces Transient Functional Bone Marrow Toxicity

223Ra is a bone-seeking, α-particle-emitting radionuclide approved for the treatment of patients with metastatic prostate cancer and is currently being tested in a variety of clinical trials for primary and metastatic cancers to bone. Clinical evaluation of 223Ra hematologic safety showed a significantly increased rate of neutropenia and thrombocytopenia in patients, hinting at myelosuppression as a side effect. Methods: In this study, we investigated the consequences of 223Ra treatment on bone marrow biology by combining flow cytometry, single-cell RNA sequencing, three-dimensional multiphoton microscopy and bone marrow transplantation analyses. Results: 223Ra accumulated in bones and induced zonal radiation damage confined to the bone interface, followed by replacement of the impaired areas with adipocyte infiltration, as monitored by 3-dimensional multiphoton microscopy ex vivo. Flow cytometry and single-cell transcriptomic analyses on bone marrow hematopoietic populations revealed transient, nonspecific 223Ra-mediated cytotoxicity on resident populations, including stem, progenitor, and mature leukocytes. This toxicity was paralleled by a significant decrease in white blood cells and platelets in peripheral blood-an effect that was overcome within 40 d after treatment. 223Ra exposure did not impair full hematopoietic reconstitution, suggesting that bone marrow function is not permanently hampered. Conclusion: Our results provide a comprehensive explanation of 223Ra reversible effects on bone marrow cells and exclude long-term myelotoxicity, supporting safety for patients.

Clinical Significance of the Highest Regional Bone Scan Index in Patients with Metastatic Castration-Resistant Prostate Cancer

Purpose

This study evaluated the clinical utility of the highest bone scan index (BSI), among other BSIs, for each bone metastatic site in patients with bone metastatic castration-resistant prostate cancer (bmCRPC).

Methods

Thirty patients, diagnosed with bmCRPC by bone scintigraphy, were included. Total BSI, the number of hot spots, and regional BSI on each hot spot from bone scintigraphy at diagnosis with bmCRPC were evaluated by VSBONE BSI®. Highest regional BSI was defined as the highest value among regional BSIs on each hot spot in each patient. Related factors to overall survival and skeletal-related events (SREs) were evaluated using the Cox proportional-hazards model.

Results

The median follow-up time from diagnosis with bmCRPC was 29.0 months. During this time, 24 patients died, of which 22 patients died from prostate cancer. On univariate analysis, alkaline phosphatase (ALP) [Hazard ratio (HR): 5.96, 95% confidence interval (CI): 2.05-17.3] and highest regional BSI (HR: 2.01, 95% CI: 1.17-7.05) had significant correlation with overall survival. On multivariate analysis, ALP (HR: 4.79, 95% CI: 1.61-14.2) had significant correlation with overall survival. SREs were found in eight patients. Only the highest regional BSI (HR: 9.99, 95% CI: 2.46-40.6) significantly correlated with SREs on univariate analysis.

Conclusion

Highest regional BSI may provide important information regarding prognosis and SREs in patients with bmCRPC.

Outcomes and Factors Associated with Completion of Radium-223 Therapy

Purpose

Radium-223 has been demonstrated in clinical trials to improve survival in castration-resistant prostate cancer (CRPC) patients with bone metastases. However, its performance in routine use remains to be fully characterized. This study aims to describe patient outcomes in the real world as well as identify factors associated with completion of the 6-dose regimen and alkaline phosphatase (ALP) response.

Methods

Thirty-six patients who received at least one dose of radium-223 at the Jewish General Hospital in Montréal, Canada, were analysed in a retrospective manner. Using logistic regression, the primary analysis aimed to identify factors associated with treatment completion, and the secondary analysis aimed to identify factors associated with ALP response.

Results

Twenty-one out of 36 patients received all 6 doses of radium-223. Fifteen patients had an ALP response, defined as a 30% decrease in ALP from baseline values. On primary analysis, baseline ALP > 120 U/L and prostate-specific antigen (PSA) > 50 μg/L were significantly associated with lower therapy completion rates (OR = 0.10, p = 0.004; OR = 0.18, p = 0.022 respectively). On adjustment for confounders, only ALP remained significant (OR = 0.14, p = 0.021). Clinical disease progression was the most common reason for treatment non-completion, and it was also associated with elevated baseline ALP (OR = 6.00, p = 0.044). On secondary analysis, previous chemotherapy for CRPC was a negative predictor of ALP response (OR = 0.15, p = 0.034).

Conclusion

Elevated baseline ALP and PSA were associated with a lower rate of radium-223 regimen completion; receiving chemotherapy for CRPC prior to radium-223 was associated with a lower rate of ALP response.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13139-022-00760-8.

Real-world patient characteristics associated with survival of 2 years or more after radium-223 treatment for metastatic castration-resistant prostate cancer (EPIX study)

Background

The real-world EPIX study was conducted to gather information about the characteristics of patients with metastatic castration-resistant prostate cancer (mCRPC) who survived ≥2 years after treatment with the alpha-emitter radium-223.

Methods

This retrospective study of electronic health records in the US Flatiron database (NCT04516161) included patients with mCRPC treated with radium-223 between January 2013 and June 2019. Median overall survival (OS) and prostate-specific antigen (PSA) response (≥50% reduction) from start of radium-223 treatment were the primary and secondary endpoints, respectively. Patient characteristics were compared between those who survived ≥2 years versus <2 years, including a subgroup who survived <6 months.

Results

In the 1180 patients identified, median OS was 12.9 months (95% CI: 12.1–13.7), and 13% of patients with data at 6 months had a PSA response. The survival groups included 775 patients (65.7%) who survived <2 years (including 264 (22.4%) who survived <6 months) and 185 patients (15.7%) who survived ≥2 years; 220 patients (18.6%) had incomplete follow-up data and were censored. On multivariate analysis, age >75 years, Eastern Cooperative Oncology Group performance status (ECOG PS) 2–4, visceral metastases, prior symptomatic skeletal events (SSEs), and prior chemotherapy were independently prognostic of reduced OS. For patients with survival ≥2 years versus <2 years, median age was 71 versus 75 years, 4% versus 14% had ECOG PS 2–4, 4% versus 10% had visceral metastases, 38% versus 44% had prior SSEs, and 16% versus 32% had prior chemotherapy.

Conclusions

In this study of men with mCRPC treated in real-world clinical practice, median OS was consistent with that seen in the phase 3 ALSYMPCA trial. Patients who survived ≥2 years after the start of radium-223 were younger and had better ECOG PS, lower disease burden, and less use of prior chemotherapy than those who survived <2 years.

Radium-223 Treatment of Patients with Metastatic Castration Resistant Prostate Cancer: Biomarkers for Stratification and Response Evaluation

Simple Summary

Radium-223 dichloride ([²²³Ra]RaCl₂; Ra-223) is an alpha-emitting radiopharmaceutical treatment for patients with metastatic castration resistant prostate cancer (mCRPC) with predominantly bone metastases. While responses to chemotherapeutic and antihormonal mCRPC treatments can be assessed by serum PSA levels, a decrease of serum PSA levels is not expected during Ra-223 therapy. Moreover, radiographic evaluation of bone metastases response is challenging. Therefore, novel biomarkers to select patients for Ra-223 treatment and monitoring response are urgently needed. In this review, we discuss the currently used and exploratory biomarkers for this purpose, including soluble and cellular factors detected in the peripheral blood, genetic defects and radiographic assessments. We conclude that some biomarkers, including metabolic products of collagen degradation and novel PET scan techniques, might hold promise as predictors of response to Ra-223 treatment. However, these biomarkers have not been extensively studied. Consequently, currently, no biomarker has established a place in patient stratification and response evaluation.

Abstract

Radium-223 dichloride ([²²³Ra]RaCl₂; Ra-223) is a targeted alpha-emitting radiopharmaceutical which results in an overall survival and health related quality of life (HRQoL) benefit in symptomatic patients with metastatic castration resistant prostate cancer (mCRPC) and predominantly bone metastasis. Although effective, options to select patients who will derive treatment benefit and to monitor and predict treatment outcomes are limited. PSA response and radiographic evaluation are commonly used in mCRPC treatment assessment but are not informative in Ra-223 treated patients. Consequently, there is a clear need for predictive and prognostic tools. In this review, we discuss the physiology of bone metastases and the mechanism of action and efficacy of Ra-223 treatment, as well as offering an outline of current innovative prognostic and predictive biomarkers.

Clinical outcomes, management, and treatment patterns in patients with metastatic castration-resistant prostate cancer treated with radium-223 in community compared to academic settings

BACKGROUND

The most common site of disease in metastatic castration-resistant prostate cancer (mCRPC) is the bone. The ALSYMPCA study demonstrated that radium-223 significantly improved overall survival (OS) in mCRPC patients with symptomatic bone metastases and without visceral metastases. However, administration requires a multidisciplinary approach and an infrastructure that supports coordination of care, which may differ by practice site. We aimed to evaluate practice patterns and treatment outcomes in patients with mCRPC treated at a community practice (CP) compared with those treated at an academic center (AC).

METHODS

This retrospective review included 200 adult mCRPC patients receiving radium-223 between January 2014 and June 2017. The primary endpoint, OS, was estimated from the date of radium-223 initiation. Secondary outcomes included a comparison of baseline characteristics, reasons for initiation and discontinuation of radium-223, and treatment sequencing. A subset analysis of OS based on the number of radium-223 doses and on sequencing of radium-223 either before or after chemotherapy was also conducted.

RESULTS

Most patients were treated at a CP (57%). Patients treated at CP sites were significantly older (74.9 vs. 71.9 years; p = .031) and had more comorbidities (Klabunde score 1.1 vs. 0.7; p = .020) than those in an AC but initiated treatment within a shorter period of time from diagnosis of mCRPC (1.3 vs. 1.9 years; p < .001) and received a greater mean number of radium-223 doses (5.4 vs. 4.8; p = .001). There were no observed differences in OS between CPs versus ACs (21.6 vs. 20.7 months; p = .306). Overall, patients who received 5-6 doses versus 1-4 doses of radium-223 had a longer median OS (23.3 vs. 6.4 months; p < .001). The most common reason for discontinuation in patients who did not complete treatment was disease progression. Overall, 43% of patients received radium-223 monotherapy and 57% concurrently with other agents.

CONCLUSIONS

Most patients received radium-223 concurrently with abiraterone acetate or enzalutamide and were able to complete 5-6 doses of radium-223. Despite differences in the populations and treatment patterns, no survival differences between patients treated in ACs versus CPs were observed. Additional real-world data are needed to validate these findings.

Early alkaline phosphatase dynamics as biomarker of survival in metastatic castration-resistant prostate cancer patients treated with radium-223

Purpose

Radium-223 is a life-prolonging therapy for castration-resistant prostate cancer (CRPC) patients with symptomatic bone metastases. However, validated biomarkers for response monitoring are lacking. The study aim was to investigate whether early alkaline phosphatase (ALP) dynamics after the first radium-223 injection can act as surrogate marker for overall survival (OS).

Methods

This retrospective multicenter study included consecutive CRPC patients treated with radium-223. Patients were divided into four subgroups based on baseline ALP level (normal/elevated) and early ALP response, defined as ≥10% ALP decrease after the first radium-223 injection. Primary endpoint was OS among the subgroups. Secondary endpoints included time to first skeletal-related event, time to ALP progression, and treatment completion rate.

Results

A total of 180 patients were included for analysis. Median OS was 13.5 months (95% confidence interval 11.5–15.5). Patients with elevated baseline ALP without ALP response after the first injection had significantly worse OS when compared to all other patients (median OS 7.9 months versus 15.7 months, hazard ratio 2.56, 95% confidence interval 1.73–3.80, P < 0.001). Multivariate analysis demonstrated that elevated baseline ALP without ALP response after the first injection, the number of prior systemic therapies, baseline LDH level, and baseline ECOG performance status were prognostic factors of OS. Patients with elevated baseline ALP without ALP response after the first injection had significantly shorter times to ALP progression and first skeletal-related event, and more frequently discontinued radium-223 therapy when compared to other patients.

Conclusion

Early treatment–induced changes in ALP after one radium-223 injection were associated with OS in metastatic CRPC patients.

Assessment of a software for semi-automatically calculating the bone scan index on bone scintigraphy scans

AIMS

The incidence of bone metastases exceeds 85% in patients who die from prostate cancer. Bone scintigraphy is the most widely used method for the early detection of bone metastases in prostate cancer. We developed a software program that semi-automatically calculated the bone scan index (BSI) on technetium-99m hydroxymethylene diphosphonate bone scintigraphy scans with a computer-aided diagnosis system (CAD) and examined whether the BSI calculated using this software could replace the extent of disease (EOD) score.

METHODS

The subjects were 175 patients who were diagnosed with prostate cancer at our hospital and underwent bone scintigraphy. We analyzed receiver operating characteristic curves to determine the BSI cutoff value between EOD groups. The cutoff value was determined based on the maximum value of the sum of the sensitivity and specificity.

RESULTS

BSI cutoff values of 0.20, 1.56, and 4.56 were used to distinguish between EOD 0 and 1-4 (sensitivity [87.2%] and specificity [100.0%]), between EOD 0- and 2-4 (sensitivity [85.2%] and specificity [92.0%]), and between EOD 0-2 and 3-4 (sensitivity [88.4%] and specificity [99.2%]), respectively.

CONCLUSION

Our results suggest that this software can calculate BSI, and the software may play a role in predicting prognosis and selecting an appropriate treatment strategy. If a sufficient number of other nuclear medicine tests are performed, creating a similar CAD system is possible.

Dynamic changes of bone metastasis predict bone-predominant status to benefit from radium-223 dichloride for patients with castration-resistant prostate cancer

Background

To best employ radium‐223 dichloride (Ra‐223) for patients with castration‐resistant prostate cancer (CRPC) and bone metastasis, we investigated the bone‐predominant status in patients treated with Ra‐223.

Methods

We retrospectively evaluated 127 CRPC patients who underwent treatment with Ra‐223. The patients were divided into three groups based on the types of dynamic changes of bone metastasis between diagnosis and just before Ra‐223: (a) only known lesions; (b) de novo lesions; (c) new progressive lesions. We developed the risk assessment using predictive factors based on progression‐free survival (PFS).

Results

During the median follow‐up period of 10.4 months, the median PFS in the only known lesions group was 11.3 months compared to 8.1 months in the de novo lesions group and 5.1 months in the new progressive lesions group (P < .001). In multivariate analysis, the type of the new progressive lesions in bone metastasis (HR 1.45, 95% CI 1.13‐1.66, P = .003), performance status of >1 (HR 1.74, 95% CI 1.04‐2.89, P = .034), PSA value of >100 ng/mL (HR 1.59, 95% CI 1.02‐2.50, P = .043), and PSA doubling time (PSADT) of <3 months (HR 1.53, 95% CI 1.11‐2.03, P = .007) were independent unfavorable predictive factors for PFS. The risk assessment for PFS was highlighted when the type of dynamic changes of bone metastasis was combined with PSADT just before Ra‐223 treatment. This was associated with non‐bone metastasis progression, especially visceral metastasis, and overall survival.

Conclusions

Risk assessment in combination with dynamic changes of bone metastasis and PSADT determines the bone‐predominant metastasis type to benefit from Ra‐223.

Radium 223-Mediated Zonal Cytotoxicity of Prostate Cancer in Bone

BACKGROUND

Bone-targeting radiotherapy with Radium-223 (Rad-223), a radioisotope emitting genotoxic alpha-radiation with limited tissue penetrance (∼100 µm), prolongs the survival of patients with metastatic prostate cancer (PCa). Confoundingly, the clinical response to Rad-223 is often followed by detrimental relapse and progression, and whether Rad-223 causes tumor-cell directed cytotoxicity in vivo remains unclear. We hypothesized that limited radiation penetrance in situ defines outcome.

METHODS

We tested Rad-223 overall response by PC3 and C4-2B human PCa cell lines in mouse bones (n = 5-18 tibiae per group). Rad-223 efficacy at subcellular resolution was determined by intravital microscopy analysis of dual-color fluorescent PC3 cells (n = 3-4 mice per group) in tissue-engineered bone constructs. In vivo data were fed into an in silico model to predict Rad-223 effectiveness in lesions of different sizes (1-27, 306 initial cells; n = 10-100 simulations) and the predictions validated in vivo by treating PCa tumors of varying sizes in bones (n = 10-14 tibiae per group). Statistical tests were performed by two-sided Student t test or by one-way ANOVA followed by Tukey's post-hoc test.

RESULTS

Rad-223 (385 kBq/kg) delayed the growth (means [SD]; comparison with control-treated mice) of PC3 (6.7 × 105[4.2 × 105] vs 2.8 × 106 [2.2 × 106], P = .01) and C4-2B tumors in bone (7.7 × 105 [4.0 × 105] vs 3.5 × 106 [1.3 × 106], P < .001). Cancer cell lethality in response to Rad-223 (385 kBq/kg) was profound but zonally confined along the bone interface compared with the more distant tumor core, which remained unperturbed (day 4; 13.1 [2.3%] apoptotic cells, 0-100 µm distance from bone vs 3.6 [0.2%], >300 µm distance; P = .01).In silico simulations predicted greater efficacy of Rad-223 on single-cell lesions (eradication rate: 88.0%) and minimal effects on larger tumors (no eradication, 16.2% growth reduction in tumors of 27 306 cells), as further confirmed in vivo for PC3 and C4-2B tumors.

CONCLUSIONS

Micro-tumors showed severe growth delay or eradication in response to Rad-223, whereas macro-tumors persisted and expanded. The relative inefficacy in controlling large tumors points to application of Rad-223 in secondary prevention of early bone-metastatic disease and regimens co-targeting the tumor core.

Real-world outcomes of radium-223 dichloride for metastatic castration resistant prostate cancer

Aim: Timing of radium-223 (Ra-223) in metastatic castration-resistant prostate cancer (mCRPC) remains challenging due to alternative options and short window of opportunity. Methods: Ra-223 treated patients in the CAPRI-registry were included. Outcomes were evaluated based on treatment line of Ra-223. Results: Out of 285 patients, 49% received Ra-223 in line ≥3. 51% completed six Ra-223 injections and 34% had a symptomatic skeletal event after first Ra-223 without differences between subgroups. After correction of known prognostic factors Ra-223 in line ≥3 (HR: 3.267; 95% CI: 1.689-6.317; p < 0.01) remained associated with worse OS. Conclusion: In the Netherlands, Ra-223 was mainly started as second or third mCRPC-treatment in 2014-2018. Later timing of Ra-223 did affect OS, but not treatment completion and occurrence of symptomatic skeletal events.

Prognostic value of the bone scan index in patients with metastatic castration-resistant prostate cancer: a systematic review and meta-analysis

Background

Many studies have reported the prognostic significance of the bone scan index (BSI) for metastatic castration-resistant prostate cancer (mCRPC); however, these reports are controversial. This study investigated the BSI in mCRPC and its relationship with prognosis.

Methods

The PubMed, Cochrane, and Embase databases were searched systematically for relevant articles published before September 1, 2019. Hazard ratios (HRs) were used to investigate the prognostic value.

Results

This study finally identified 9 eligible studies. The results suggested that high baseline BSI predicted poor OS (HR = 1.331, 95% CI: 1.081–1.640) and that elevated ΔBSI also predicted poor OS (HR = 1.220, 95% CI: 1.015–1.467). The subgroup analysis stratified by ethnicity showed that the baseline BSI and ΔBSI predicted poor OS in the Asian population but not in the Caucasian population. We also performed a subgroup analysis based on the different cut-off values of baseline BSI. The subgroup of ≤1 showed a significant association with OS in mCRPC patients.

Conclusion

Our study demonstrated that high baseline BSI and elevated ΔBSI predicted poor OS in patients with mCRPC. Hence, the BSI can serve as a prognostic indicator for mCRPC patients and may therefore guide clinical treatment in the future.

Safety and activity of radium-223 in metastatic castration-resistant prostate cancer: the experience of Istituto Nazionale dei Tumori

INTRODUCTION

Therapeutic decision-making in metastatic castration-resistant prostate cancer (mCRPC) represents an open challenge. Radium-223 is approved for patients with symptomatic bone metastases, no visceral involvement, progressing after at least 2 lines of systemic therapy, or ineligible for any other systemic treatment.

METHODS

We performed a retrospective, observational study on patients with mCRPC treated with radium-223 at our institution outside of clinical trials, to assess the safety and activity in a real-world population. Data regarding baseline patient/disease characteristics and treatment outcomes (number of cycles, treatment-related adverse events [AEs], cause of discontinuation, and best response) were collected.

RESULTS

Overall, 41 patients were treated from September 2015 to September 2018. Median age was 73 years; baseline Eastern Cooperative Oncology Group Performance Status (ECOG PS) was 0, 1, or 2 in 15%, 80%, and 5% of cases, respectively; and 3%, 41%, 44%, and 12% of patients had <6, 6-20, >20, and superscan bone lesions, respectively. A median number of 5 cycles (interquartile range 3-6) with median dose 19.52 MBq (interquartile range 12.87-24.83) was received. Treatment schedule was completed in 49% of cases; discontinuations due to AEs, disease-related death, or disease progression occurred in 24%, 33%, and 43% of patients, respectively. Any-grade AEs occurred in 73% and grade 3/4 treatment-related AEs occurred in 29% of patients, mainly anemia, decreased platelet count, and fatigue. No skeletal-related events or treatment-related deaths were recorded. After treatment, 66%, 2%, and 32% of patients had a stable, improved, or deteriorated ECOG PS versus baseline, respectively, and 24%, 61%, and 15% reported a stable, improved, or worsened pain symptom control. Post-treatment versus baseline alkaline phosphatase was reduced or stable in 46% and increased in 54% of patients, whereas prostate-specific antigen was decreased or stable in 83% and increased in 17% of patients.

CONCLUSIONS

Our study provides clinically useful real-world data on radium-223, highlighting the importance of multidisciplinary patient management to guarantee the best continuum of care for patients with mCRPC.

A prospective observational registry evaluating clinical outcomes of Radium-223 treatment in a nonstudy population

The ALSYMPCA study established a 3.6 month Overall Survival (OS) benefit in metastatic Castration Resistant Prostate Cancer (mCRPC) patients treated with Radium-223 dichloride (Ra-223) over placebo. Here we report clinical outcomes of Ra-223 treatment in a nonstudy population. In this prospective registry, patients from 20 Dutch hospitals were included prior to Ra-223 treatment. Clinical parameters collected included previous treatments and Adverse Events. Primary outcome was 6 months Symptomatic Skeletal Event (SSE)-free survival, while secondary outcomes included Progression-Free Survival (PFS) and Overall Survival (OS). Of the 305 patients included, 300 were evaluable. The mean age was 73.6 years, 90% had ≥6 bone metastases and 74.1% were pretreated with Docetaxel, 19.5% with Cabazitaxel and 80.5% with Abiraterone and/or Enzalutamide. Of all patients, 96.7% were treated with Ra-223 and received a median of 5 cycles. After a median follow-up of 13.2 months, 6 months SSE-free survival rate was 83%, median PFS was 5.1 months and median OS was 15.2 months. Six months SSE-free survival rate and OS were comparable with those reported in ALSYMPCA. "Previous Cabazitaxel treatment" and "bone-only metastases" were independent predictors of a shorter and longer PFS, respectively, while above-median LDH and "bone-only metastases" were independent predictors of shorter and longer OS, respectively. Toxicity was similar as reported in the ALSYMPCA trial. These results suggest that in a nonstudy population, Ra-223 treatment is well-tolerated, equally effective as in the ALSYMPCA population and that patients not previously treated with Cabazitaxel benefit most from Ra-223.

Assessing Radiographic Response to 223Ra with an Automated Bone Scan Index in Metastatic Castration-Resistant Prostate Cancer Patients

For effective clinical management of patients being treated with ²²³Ra, there is a need for radiographic response biomarkers to minimize disease progression and to stratify patients for subsequent treatment options. The objective of this study was to evaluate an automated bone scan index (aBSI) as a quantitative assessment of bone scans for radiographic response in patients with metastatic castration-resistant prostate cancer (mCRPC). Methods: In a multicenter retrospective study, bone scans from patients with mCRPC treated with monthly injections of ²²³Ra were collected from 7 hospitals in Sweden. Patients with available bone scans before treatment with ²²³Ra and at treatment discontinuation were eligible for the study. The aBSI was generated at baseline and at treatment discontinuation. The Spearman rank correlation was used to correlate aBSI with the baseline covariates: alkaline phosphatase (ALP) and prostate-specific antigen (PSA). The Cox proportional-hazards model and Kaplan-Meier curve were used to evaluate the association of covariates at baseline and their change at treatment discontinuation with overall survival (OS). The concordance index (C-index) was used to evaluate the discriminating strength of covariates in predicting OS. Results: Bone scan images at baseline were available from 156 patients, and 67 patients had both a baseline and a treatment discontinuation bone scan (median, 5 doses; interquartile range, 3-6 doses). Baseline aBSI (median, 4.5; interquartile range, 2.4-6.5) was moderately correlated with ALP (r = 0.60, P < 0.0001) and with PSA (r = 0.38, P = 0.003). Among baseline covariates, aBSI (P = 0.01) and ALP (P = 0.001) were significantly associated with OS, whereas PSA values were not (P = 0.059). After treatment discontinuation, 36% (24/67), 80% (54/67), and 13% (9/67) of patients demonstrated a decline in aBSI, ALP, and PSA, respectively. As a continuous variable, the relative change in aBSI after treatment, compared with baseline, was significantly associated with OS (P < 0.0001), with a C-index of 0.67. Median OS in patients with both aBSI and ALP decline (median, 134 wk) was significantly longer than in patients with ALP decline only (median, 77 wk; P = 0.029). Conclusion: Both aBSI at baseline and its change at treatment discontinuation were significant parameters associated with OS. The study warrants prospective validation of aBSI as a quantitative imaging response biomarker to predict OS in patients with mCRPC treated with ²²³Ra.

Phase 3 Assessment of the Automated Bone Scan Index as a Prognostic Imaging Biomarker of Overall Survival in Men With Metastatic Castration-Resistant Prostate Cancer: A Secondary Analysis of a Randomized Clinical Trial

Importance

Prostate cancer commonly metastasizes to bone, and bone metastases are associated with pathologic fractures, pain, and reduced survival. Bone disease is routinely visualized using the technetium Tc 99m (99mTc) bone scan; however, the standard interpretation of bone scan data relies on subjective manual assessment of counting metastatic lesion numbers. There is an unmet need for an objective and fully quantitative assessment of bone scan data.

Objective

To clinically assess in a prospectively defined analysis plan of a clinical trial the automated Bone Scan Index (aBSI) as an independent prognostic determinant of overall survival (OS) in men with metastatic castration-resistant prostate cancer (mCRPC).

Design, Setting, and Participants

This investigation was a prospectively planned analysis of the aBSI in a phase 3 multicenter randomized, double-blind, placebo-controlled clinical trial of tasquinimod (10TASQ10). Men with bone metastatic chemotherapy-naïve CRPC were recruited at 241 sites in 37 countries between March 2011 and August 2015. The statistical analysis plan to clinically evaluate the aBSI was prospectively defined and locked before unmasking of the 10TASQ10 study. The analysis of aBSI was conducted between May 25, 2016, and June 3, 2017.

Main Outcomes and Measures

The associations of baseline aBSI with OS, radiographic progression-free survival (rPFS), time to symptomatic progression, and time to opiate use for cancer pain.

Results

Of the total 1245 men enrolled, 721 were evaluable for the aBSI. The mean (SD) age (available for 719 men) was 70.6 (8.0) years (age range, 47-90 years). The aBSI population was representative of the total study population based on baseline characteristics. The aBSI (median, 1.07; range, 0-32.60) was significantly associated with OS (hazard ratio [HR], 1.20; 95% CI, 1.14-1.26; P < .001). The median OS by aBSI quartile (lowest to highest) was 34.7, 27.3, 21.7, and 13.3 months, respectively. The discriminative ability of the aBSI (C index, 0.63) in prognosticating OS was significantly higher than that of the manual lesion counting (C index, 0.60) (P = .03). In a multivariable survival model, a higher aBSI remained independently associated with OS (HR, 1.06; 95% CI, 1.01-1.11; P = .03). A higher aBSI was also independently associated with time to symptomatic progression (HR, 1.18; 95% CI, 1.13-1.23; P < .001) and time to opiate use for cancer pain (HR, 1.21; 95% CI, 1.14-1.30; P < .001).

Conclusions and Relevance

To date, this investigation is the largest prospectively analyzed study to validate the aBSI as an independent prognostic imaging biomarker of survival in mCRPC. These data support the prognostic utility of the aBSI as an objective imaging biomarker in the design and eligibility of clinical trials of systemic therapies for patients with mCRPC.

Trial Registration

ClinicalTrials.gov Identifier: NCT01234311.

Measuring the unmeasurable: automated bone scan index as a quantitative endpoint in prostate cancer clinical trials

BACKGROUND

Up to 90% of men with metastatic castration-resistant prostate cancer (mCRPC) will have a distribution of disease that includes bone metastases demonstrated on a Technetium-99m (^99mTc-MDP) bone scan. The Prostate Cancer Working Group 2 and 3 Consensus Criteria standardized the criteria for assessing progression based on the development of new lesions. These criteria have been recognized by regulatory authorities for drug approval. The bone scan index (BSI) is a method to quantitatively measure the burden of bony disease, and can assess both disease progression and regression. The automated BSI (aBSI) is a method of computer analysis to assess BSI, and is being qualified as a clinical trials endpoint.

METHODS

Manual searching was used to identify the literature on BSI and aBSI. We summarize the most relevant aspects of the retrospective and prospective studies evaluating aBSI measurements, and provide a critical discussion on the potential advantages and caveats of aBSI.

RESULTS

The development of neural artificial networks (EXINI boneBSI) to automatically determine the BSI reduces the turnaround time for assessing BSI with high reproducibility and accuracy. Several studies showed that the concordance between aBSI and BSI, as well as the interobserver concordance of aBSI, was >0.95. In a phase 3 assessment of aBSI, a doubling value increased the risk of death in 20%, pre-treatment aBSI values independently correlated with overall survival (OS) and time to symptomatic progression. Retrospective studies suggest that a decrease in aBSI after treatment may correlate with higher survival when compared with increasing aBSI.

CONCLUSIONS

aBSI provides a quantitative measurement that is feasible, reproducible, and in analyses to date correlates with OS and symptomatic progression. These findings support the aBSI to risk-stratify men with mCRPC for clinical trial enrollment. Future studies quantifying aBSI change over time as an intermediate endpoint for evaluating new systemic therapies are needed.

Evaluating radium-223 response in metastatic castration-resistant prostate cancer with imaging

Radium-223 is a first-in-class targeted alpha therapy indicated for treating bone metastases from metastatic castration-resistant prostate cancer (mCRPC) without visceral metastases. Imaging plays an important role in the selection of patients eligible for radium-223 therapy. In the ALSYMPCA trial protocol, bone scintigraphy was used to detect lesions, essentially osteoblastic bone metastases, whereas computed tomography (CT) was used to exclude visceral metastases, with no interim imaging until treatment completion unless clinically indicated. Yet, questions remain: How can we monitor treatment progress more closely and evaluate treatment response more precisely? In the cases discussed herein, interim evaluation of response to radium-223 showed discordance between bone scintigraphy and ¹⁸ F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT in the patterns of bone lesions observed, that is more lesions were detected on PET/CT. It is postulated that the additional lesions may be attributed to bone marrow metastases that were not effectively targeted by radium-223 as its alpha radiation do not reach deep into the bone marrow. Although the clinical significance of the discordance requires further clarification, it makes sense to consider radium-223 early on in the course of mCRPC, when marrow involvement is minimal, so as to optimize treatment outcomes.

Radium-223 in patients with metastatic castration-resistant prostate cancer: Efficacy and safety in clinical practice

Radium-223 has improved overall survival (OS) and reduced symptomatic skeletal events (SSE) in patients with metastatic castration-resistant prostate cancer (mCRPC) and bone metastases (ALSYMPCA trial). Our aim was to assess clinical and biochemical factors related to survival, safety and survival outcomes of Radium-223 in a clinical practice setting. We retrospectively analysed 32 mCRPC patients treated with Radium-223, assessing bone scan, pain reduction, alkaline phosphatase (ALP) and prostate-specific antigen (PSA) response (≥30% reduction). At scintigraphic assessment, 41% had partial response with a disease control rate of 91%; 56% had ALP response and 25% had PSA response; 41% had pain reduction with pain control of 72%. Scintigraphic response and stability were correlated with longer median progression-free survival (mPFS) (13 and 12 vs. 6 months; P=0.002) and mOS (16 and 12 vs. 6 months; P=0.003). ALP response was associated with longer mPFS (13 vs. 12 months; P=0.2) and mOS (16 vs. 12 months; P=0.2). PSA response was associated with longer mPFS (13 vs. 12 months; P=0.02), whereas mOS could not be computed. Pain response and stability were associated with survival benefit according to mPFS (13 and 12 vs. 9 months) and mOS (both 16 vs. 12 months) without statistical significance. Baseline ALP <220 UI/l, Eastern Cooperative Oncology Group (ECOG) performance status 0 and absence of previous chemotherapy correlated with statistically significantly longer survival outcomes. Skeletal-related events (SRE) occurred in three patients and median time to first SRE was 9.5 months, mPFS was 12 months and mOS 14 months. G3-G4 toxicities developed in 16% of patients. Our results are in line with those reported in the pivotal trial and in other retrospective studies. In conclusion, Radium-223 was associated with high scintigraphic, biochemical and pain response rates and was tolerated well by most patients. Response to Radium-223 and better baseline factors correlated to longer survival in clinical practice experience as in the clinical trial setting.

Patient Selection for Radium-223 Therapy in Patients With Bone Metastatic Castration-Resistant Prostate Cancer: New Recommendations and Future Perspectives

Radium-223 therapy was registered in 2013 as a new life-prolonging therapeutic option for patients with symptomatic bone metastatic castration-resistant prostate cancer after the phase 3 ALSYMPCA study. Postregistration reports on the use of radium-223 in real-world populations demonstrate that appropriate selection of patients for radium-223 therapy is challenging. While primarily retrospective and post hoc studies identified prognostic variables associated with overall survival, validated predictive biomarkers are still lacking. Important pretherapeutic prognostic variables include the number of prior therapies, baseline Eastern Cooperative Oncology Group performance status, baseline extent of bone metastatic disease, and baseline alkaline phosphatase, prostate-specific antigen, and lactate dehydrogenase levels. We reviewed the currently available literature to provide recommendations on patient selection for radium-223 therapy in patients with bone metastatic castration-resistant prostate cancer. In addition, the recent evidence from the report of the European Medicines Agency's Pharmacovigilance Risk Assessment Committee regarding the restricted use of radium-223 after interim data analysis of the ERA-223 trial has been incorporated into our recommendations. Future perspectives are also discussed, including radium-223 re-treatment, the use of concomitant therapies, and the implementation of pretherapeutic molecular analysis for treatment stratification.

Bone-Targeting Radiopharmaceuticals as Monotherapy or Combined With Chemotherapy in Patients With Castration-Resistant Prostate Cancer Metastatic to Bone

In patients with metastatic castration-resistant prostate cancer, bone is the most common site for metastases. Because of their osteoblastic character, these lesions are very suitable for treatment with bone-seeking radiopharmaceuticals (RPs). Nowadays, radium-223-chloride is the only RP with a proven benefit in overall survival, whereas the β-emitting RPs are used for pain palliation. In the past, many trials that investigated RPs alone, or in combination with chemotherapy have been performed. Because of different designs, characteristics of included patients, and chemotherapeutical and RP regimens, interpretation of the promising data and positioning of RPs in the treatment of metastatic prostate cancer has become difficult. In this review, we provide an overview of the existing data per RP with a focus on the different RPs in combination with chemotherapy. Furthermore, we aim to clarify the benefits on pain response and quality of life. Finally, we focus on the optimal timing and use of biomarkers in the treatment of patients with castration-resistant prostate cancer with RPs.

Assessment of Skeletal Tumor Load in Metastasized Castration-Resistant Prostate Cancer Patients: A Review of Available Methods and an Overview on Future Perspectives

Metastasized castration-resistant prostate cancer (mCRPC), is the most advanced form of prostate neoplasia, where massive spread to the skeletal tissue is frequent. Patients with this condition are benefiting from an increasing number of treatment options. However, assessing tumor response in patients with multiple localizations might be challenging. For this reason, many computational approaches have been developed in the last decades to quantify the skeletal tumor burden and treatment response. In this review, we analyzed the progressive development and diffusion of such approaches. A computerized literature search of the PubMed/Medline was conducted, including articles between January 2008 and March 2018. The search was expanded by manually reviewing the reference list of the chosen articles. Thirty-five studies were identified. The number of eligible studies greatly increased over time. Studies could be categorized in the following categories: automated analysis of 2D scans, SUV-based thresholding, hybrid CT- and SUV-based thresholding, and MRI-based thresholding. All methods are discussed in detail. Automated analysis of bone tumor burden in mCRPC is a growing field of research; when choosing the appropriate method of analysis, it is important to consider the possible advantages as well as the limitations thoroughly.

223Ra Therapy in Patients With Advanced Castration-Resistant Prostate Cancer With Bone Metastases: Lessons from Daily Practice

PURPOSE

To identify pre-therapeutic variables associated with overall survival (OS) in patients treated with Ra.

METHODS

Data from 45 CRPC patients treated with Ra were retrospectively analyzed. All patients who received at least one Ra injection were included in the study. Cox proportional hazard regression models were used to estimate hazard ratio's (HR) and to test for association.

RESULTS

Twenty-one patients (47%) received six Ra injections and 24 patients (53%) received one to five Ra injections. Median OS since start of Ra was 13.0 months (95% confidence interval (CI) 8.2-17.8). Patients who completed Ra therapy had a median OS of 19.7 months (95% CI 14.9-24.6), while patients who received one to five Ra injections had a median OS of 5.9 months (95% CI 3.8-8.1; P < 0.001).Univariable analysis showed poor baseline ECOG performance status (PS), baseline opioid use, lowered baseline hemoglobin, and elevated prostate-specific antigen, alkaline phosphatase and lactate dehydrogenase (LD) levels were significantly associated with OS. Multivariable Cox regression analysis demonstrated that poor baseline ECOG PS (HR 10.6) and high LD levels (HR 7.7) were pre-therapeutic variables that predicted poor OS.

CONCLUSIONS

In a multivariable Cox regression model, good baseline ECOG PS and low LD levels were significantly associated with longer OS in patients treated with Ra. These variables may be used for stratification of CRPC patients for Ra therapy. Prospective studies to evaluate these variables are warranted, to develop a nomogram to select patients properly. In this retrospective study, predictors of overall survival in 45 metastatic castration-resistant prostate cancer patients treated with Ra therapy were evaluated. Baseline ECOG performance status and lactate dehydrogenase levels turned out to be significant in a multivariable prediction model for overall survival.

Hematologic Toxicity From Radium-223 Therapy for Bone Metastases in Castration-Resistant Prostate Cancer: Risk Factors and Practical Considerations

Radium-223 dichloride is an α-emitting radiopharmaceutical that localizes to bone matrix and is approved for the treatment of patients with metastatic castration-resistant prostate cancer (CRPC) and symptomatic bone metastases. The cumulative impact of Ra-223 and other therapeutic agents for metastatic CRPC on myelosuppression in bone marrow is unknown. The phase 3 randomized, double-blind, placebo-controlled ALSYMPCA trial of Ra-223 in patients with CRPC and symptomatic bone metastases demonstrated a significant improvement in overall survival. Of the 571 patients subsequently followed for 3 years, few in either the Ra-223 or placebo arm experienced hematologic adverse events. Little evidence shows secondary malignancies associated with Ra-223 treatment; only 2 cases of secondary leukemia after Ra-223 treatment were found in the literature. The goals of this review were to summarize safety and efficacy results from clinical trials and institutional safety data pertaining to hematologic adverse events occurring with Ra-223, and to discuss practical management issues.

Skeletal standardized uptake values obtained by quantitative SPECT/CT as an osteoblastic biomarker for the discrimination of active bone metastasis in prostate cancer

Purpose

To investigate the improvement of prognostication of active bone metastatic burden by discriminating bone metastases from degenerative changes in hot foci, using skeletal standardized uptake values (SUVs) by quantitative bone single photon emission tomography/computed tomography (SPECT/CT) in patients with prostate cancer.

Methods

We investigated 170 patients with prostate cancer who underwent skeletal quantitative SPECT/CT using ^99mTc-methylene-diphosphonate (MDP), through conjugate gradient reconstruction with tissue zoning, attenuation, and scatter corrections applied, called as CGZAS reconstruction, in a retrospective cohort study. The maximum, peak, and average SUVs (SUVmax, SUVpeak, and SUVave, respectively) were obtained for visually normal thoracic (T; n = 100) and lumbar (L; n = 140) vertebral bodies as controls, as well as for bone metastases (n = 126) and degenerative changes (n = 114) as hot foci. They were also correlated with age, body-weight, height, biochemistry data, and extent of disease (EOD). Discrimination accuracy of the SUVs for bone metastases in hot foci was evaluated by a patient-based and lesion-based receiver-operator characteristic curve (ROC) analysis.

Results

The skeletal SUVmax was 7.58 ± 2.42 for T, 8.12 ± 12.24 for L, 16.73 ± 6.74 for degenerative changes, and 40.90 ± 33.46 for bone metastases. The SUVs of the bone metastasis group were significantly (p < 0.001) greater than of the other three groups. With disease extent, serum alkaline phosphatase and prostate specific antigen were increased, while SUVs for bone metastases were decreased in EOD grade 4. In ROC analyses for bone metastases by skeletal SUVs demonstrating the diagnostic accuracy of skeletal SUVs for discriminating bone metastasis from degenerative changes in hot foci, area under curves were 0.840, 0.817, and 0.845 in patient-based mode, and 0.932, 0.920, and 0.930 in lesion-based mode.

Conclusions

The skeletal SUVs by ^99mTc-MDP SPECT/CT for active bone metastases were greater than those for degenerative changes in patients with prostate cancer, with a feasible discrimination accuracy in the hot foci. Therefore, skeletal SUVs, especially SUVmax, in quantitative bone SPECT/CT may be helpful indices for the prognostication of bone metastatic burden, improving discrimination of active bone osteoblastic metastases in patients with prostate cancer from frequently coexisting degenerative changes.

Radium 223 dichloride for prostate cancer treatment

Prostate cancer is the most common malignant disease in men. Several therapeutic agents have been approved during the last 10 years. Among them, radium-223 dichloride (Xofigo^®) is a radioactive isotope that induces irreversible DNA double-strand breaks and consequently tumor cell death. Radium-223 dichloride is a calcium-mimetic agent that specifically targets bone lesions. Radium-223 dichloride has been approved for the treatment of metastatic castration-resistant prostate cancer with symptomatic bone metastases, without known visceral metastases. In this review, first we summarize the interplay between prostate tumor cells and bone microenvironment; then, we discuss radium-223 dichloride mechanism of action and present the results of the available clinical trials and future developments for this new drug.

Prognostic value of bone scan index as an imaging biomarker in metastatic prostate cancer: a meta-analysis

Background

The prognostic value of the bone scan index (BSI) in metastatic prostate cancer (mPCa) remained controversial. Therefore, we performed a meta-analysis to determine the predictive value of BSI and survival in patients with mPCa.

Materials and Methods

A literature search was performed in PubMed, Embase, Web of Science and Cochrane library databases. Hazard ratios (HRs), concordance indices (C-indices) were extracted to estimate the relationship between BSI and survival in patients with mPCa. Subgroup analyses were conducted on different types of mPCa, ethnics, cut-off values and sample sizes.

Results

14 high quality studies involving 1295 patients with mPCa were included in this meta-analysis. The pooled results indicated that high basline BSI and elevated BSI change on treatment (ΔBSI) were significantly predictive of poor overall survial (HR = 1.29, P < 0.001; HR = 1.27, P < 0.001, respectively). Baseline BSI was also significantly related to cancer specific survival (HR = 1.65, P = 0.019) and prostate specific antigen recurrence survival (HR = 2.26, P < 0.001). Subgroup analysis supported main results. Moreover, BSI could increase the C-indices of predictive models.

Conclusions

Baseline BSI and ΔBSI may be beneficial to mPCa prognosis in clinical monitor and treatment. Further high quality studies with larger sample size are required in the future.

Diagnostic performance of a computer-assisted diagnosis system for bone scintigraphy of newly developed skeletal metastasis in prostate cancer patients: search for low-sensitivity subgroups

Purpose

The computer-assisted diagnostic system for bone scintigraphy (BS) BONENAVI is used to evaluate skeletal metastasis. We investigated its diagnostic performance in prostate cancer patients with and without skeletal metastasis and searched for the problems.

Methods

An artificial neural network (ANN) value was calculated in 226 prostate cancer patients (124 with skeletal metastasis and 101 without) using BS. Receiver operating characteristic curve analysis was performed and the sensitivity and specificity determined (cutoff ANN = 0.5). Patient’s situation at the time of diagnosis of skeletal metastasis, computed tomography (CT) type, extent of disease (EOD), and BS uptake grade were analyzed. False-negative and false-positive results were recorded.

Results

BONENAVI showed 82% (102/124) of sensitivity and 83% (84/101) specificity for metastasis detection. There were no significant differences among CT types, although low EOD and faint BS uptake were associated with low ANN values and low sensitivity. Patients showed lower sensitivity during the follow-up period than staging work-up. False-negative lesions were often located in the pelvis or adjacent to it. They comprised not only solitary, faint BS lesions but also overlaying to urinary excretion.

Conclusions

BONENAVI with BS has good sensitivity and specificity for detecting prostate cancer’s osseous metastasis. Low EOD and faint BS uptake are associated with low sensitivity but not the CT type. Prostate cancer patients likely to have false-negative results during the follow-up period had a solitary lesion in the pelvis with faint BS uptake or lesions overlaying to urinary excretion.