Addition of radium-223 to abiraterone acetate and prednisone or prednisolone in patients with castration-resistant prostate cancer and bone metastases (ERA 223): a randomised, double-blind, placebo-controlled, phase 3 trial

Crosstalk between bone metastatic cancer cells and sensory nerves in bone metastatic progression

Although the role of peripheral nerves in cancer progression has been appreciated, little is known regarding cancer/sensory nerve crosstalk and its contribution to bone metastasis and associated pain. In this study, we revealed that the cancer/sensory nerve crosstalk plays a crucial role in bone metastatic progression. We found that (i) periosteal sensory nerves expressing calcitonin gene-related peptide (CGRP) are enriched in mice with bone metastasis; (ii) cancer patients with bone metastasis have elevated CGRP serum levels; (iii) bone metastatic patient tumor samples express elevated calcitonin receptor-like receptor (CRLR, a CGRP receptor component); (iv) higher CRLR levels in cancer patients are negatively correlated with recurrence-free survival; (v) CGRP induces cancer cell proliferation through the CRLR/p38/HSP27 pathway; and (vi) blocking sensory neuron-derived CGRP reduces cancer cell proliferation in vitro and bone metastatic progression in vivo. This suggests that CGRP-expressing sensory nerves are involved in bone metastatic progression and that the CGRP/CRLR axis may serve as a potential therapeutic target for bone metastasis.

Japanese clinical practice guidelines for prostate cancer 2023

This fourth edition of the Japanese Clinical Practice Guidelines for Prostate Cancer 2023 is compiled. It was revised under the leadership of the Japanese Urological Association, with members selected from multiple academic societies and related organizations (Japan Radiological Society, Japanese Society for Radiation Oncology, the Department of EBM and guidelines, Japan Council for Quality Health Care (Minds), Japanese Society of Pathology, and the patient group (NPO Prostate Cancer Patients Association)), in accordance with the Minds Manual for Guideline Development (2020 ver. 3.0). The most important feature of this revision is the adoption of systematic reviews (SRs) in determining recommendations for 14 clinical questions (CQs). Qualitative SRs for these questions were conducted, and the final recommendations were made based on the results through the votes of 24 members of the guideline development group. Five algorithms based on these results were also created. Contents not covered by the SRs, which are considered textbook material, have been described in the general statement. In the general statement, a literature search for 14 areas was conducted; then, based on the general statement and CQs of the Japanese Clinical Practice Guidelines for Prostate Cancer 2016, the findings revealed after the 2016 guidelines were mainly described. This article provides an overview of these guidelines.

Risk of Fractures and Falls in Men with Advanced or Metastatic Prostate Cancer Receiving Androgen Deprivation Therapy and Treated with Novel Androgen Receptor Signalling Inhibitors: A Systematic Review and Meta-analysis of Randomised Controlled Trials

CONTEXT

The addition of androgen receptor signalling inhibitors (ARSIs) to standard androgen deprivation therapy (ADT) has improved survival outcomes in patients with advanced prostate cancer (PCa). Advanced PCa patients have a higher incidence of osteoporosis, compounded by rapid bone density loss upon commencement of ADT resulting in an increased fracture risk. The effect of treatment intensification with ARSIs on fall and fracture risk is unclear.

OBJECTIVE

To assess the risk of falls and fractures in men with PCa treated with ARSIs.

EVIDENCE ACQUISITION

A systematic review of EMBASE, MEDLINE, The Cochrane Library, and The Health Technology Assessment Database for randomised control trials between 1990 and June 2023 was conducted in accordance with Preferred Reporting Items for Systematic Review and Meta-analyses guidance. Risk ratios were estimated for the incidence of fracture and fall events. Subgroup analyses by grade of event and disease state were conducted.

EVIDENCE SYNTHESIS

Twenty-three studies were eligible for inclusion. Fracture outcomes were reported in 17 studies (N = 18 811) and fall outcomes in 16 studies (N = 16 537). A pooled analysis demonstrated that ARSIs increased the risk of fractures (relative risk [RR] 2.32, 95% confidence interval [CI] 2.00-2.71; p < 0.01) and falls (RR 2.22, 95% CI 1.81-2.72; p < 0.01) compared with control. A subgroup analysis demonstrated an increased risk of both fractures (RR 2.13, 95% CI 1.70-2.67; p < 0.01) and falls (RR 2.19, 95% CI 1.53-3.12; p < 0.0001) in metastatic hormone-sensitive PCa patients, and an increased risk of fractures in the nonmetastatic (RR 2.27, 95% CI 1.60-3.20; p < 0.00001) and metastatic castrate-resistant (RR 2.85, 95% CI 2.16-3.76; p < 0.00001) settings. The key limitations include an inability to distinguish fragility from pathological fractures and potential for a competing risk bias.

CONCLUSIONS

Addition of an ARSI to standard ADT significantly increases the risk of fractures and falls in men with prostate cancer.

PATIENT SUMMARY

We found a significantly increased risk of both fractures and falls with a combination of novel androgen signalling inhibitors and traditional forms of hormone therapy.

From Oncogenesis to Theranostics: The Transformative Role of PSMA in Prostate Cancer

Prostate cancer, a leading cause of cancer-related mortality among men, is characterized by complex genetic and epigenetic alterations, dysregulation of oncogenic pathways, and a dynamic tumor microenvironment. Advances in molecular diagnostics and targeted therapies have significantly transformed the management of this disease. Prostate-specific membrane antigen (PSMA) has emerged as a critical biomarker, enhancing the precision of prostate cancer diagnosis and treatment. Theranostics, which integrates PSMA-targeted imaging with radioligand therapies, has shown remarkable efficacy in detecting and treating advanced prostate cancer. By leveraging the dual capabilities of PSMA-based diagnostics and therapeutic agents, theranostics offers a personalized approach that improves patient outcomes. This comprehensive review explores the latest developments in PSMA-targeted theranostics and their impact on the future of prostate cancer management, highlighting key clinical trials and emerging therapeutic strategies.

EAU-EANM-ESTRO-ESUR-ISUP-SIOG Guidelines on Prostate Cancer. Part II-2024 Update: Treatment of Relapsing and Metastatic Prostate Cancer

BACKGROUND AND OBJECTIVE

The European Association of Urology (EAU)-European Association of Nuclear Medicine (EANM)-European Society for Radiotherapy and Oncology (ESTRO)-European Society of Urogenital Radiology (ESUR)-International Society of Urological Pathology (ISUP)-International Society of Geriatric Oncology (SIOG) guidelines on the treatment of relapsing, metastatic, and castration-resistant prostate cancer (PCa) have been updated. Here we provide a summary of the 2024 guidelines.

METHODS

The panel performed a literature review of new data, covering the time frame between 2020 and 2023. The guidelines were updated and a strength rating for each recommendation was added on the basis of a systematic review of the evidence.

KEY FINDINGS AND LIMITATIONS

Risk stratification for relapsing PCa after primary therapy may guide salvage therapy decisions. New treatment options, such as androgen receptor-targeted agents (ARTAs), ARTA + chemotherapy combinations, PARP inhibitors and their combinations, and prostate-specific membrane antigen-based therapy have become available for men with metastatic PCa.

CONCLUSIONS AND CLINICAL IMPLICATIONS

Evidence for relapsing, metastatic, and castration-resistant PCa is evolving rapidly. These guidelines reflect the multidisciplinary nature of PCa management. The full version is available online (http://uroweb.org/guideline/ prostate-cancer/).

PATIENT SUMMARY

This article summarises the 2024 guidelines for the treatment of relapsing, metastatic, and castration-resistant prostate cancer. These guidelines are based on evidence and guide doctors in discussing treatment decisions with their patients. The guidelines are updated every year.

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.

Radium-223 Treatment Produces Prolonged Suppression of Resident Osteoblasts and Decreased Bone Mineral Density in Trabecular Bone in Osteoblast Reporter Mice

Radium 223 (Ra-223) is an α-emitting bone-homing radiopharmaceutical that targets tumor-induced osteoblasts and is used to reduce bone pain and prolong overall survival in men with bone-metastatic, castrate-resistant prostate cancer. However, increased fracture risk in skeletal sites with no bone metastasis has been observed in patients treated with Ra-223. Both luciferase- or green fluorescence protein (GFP)-labeled osteoblast reporter mice were used to monitor the effect of Ra-223 on resident osteoblasts and normal bone structure. Upon Ra-223 treatment, 70% of resident osteoblasts were reduced within 2 days, and the osteoblast reduction lasted for at least 18 weeks without detectable recovery, as measured by in vivo bioluminescent imaging. In GFP-labeled osteoblast reporter mice, Ra-223 mainly reduced osteoblasts localized in the trabecular bone areas; the osteoblasts in the growth plates were less affected. Micro-computed tomography analyses showed that Ra-223 significantly reduced bone mineral density and bone microstructure in the trabecular area of femurs but not in the cortical bone. Tumor-induced bone was generated by inoculating osteogenic TRAMP-BMP4 prostate cancer cells into the mouse femurs; Ra-223 treatment significantly reduced tumor-induced osteoblasts. Our study shows that Ra-223 affects bone structures that are not involved in bone metastasis. Strategies that improve bone health may reduce fracture risk in patients receiving Ra-223.

Combination Strategies and Targeted Radionuclide Therapies

Combination models utilising treatments from two or more therapeutic classes are well established in cancer care. In the new era of theranostic (theragnostic) medicine there is an ongoing need to identify and refine novel combination strategies to optimise multidisciplinary care for conditions commonly encountered in nuclear medicine such as neuroendocrine neoplasms (NEN), prostate cancer (PCa), and thyroid cancer, along with seeking advancements in molecular imaging and therapy techniques for other tumour streams. This concise review explores the background of theranostic monotherapy, established approaches to combination strategies in theranostics, and emerging targeted radionuclide therapies in use or under active investigation, with a focus on Australian-led studies.

Targeted Radiopharmaceutical Therapy for Bone Metastases

Radiopharmaceutical approaches for targeting bone metastasis have traditionally focused on palliation of pain. Several agents have been clinically used over the last several decades and have proven value in pain palliation providing pain relief and improving quality of life. The role is well established across several malignancies, most commonly used in osteoblastic prostate cancer patients. These agents have primarily based on targeting and uptake in bone matrix and have mostly included beta emitting isotopes. The advent alpha emitter and FDA approval of 223Ra-dichloride has created a paradigm shift in clinical approach from application for pain palliation to treatment of bone metastasis. The approval of 223Ra-dichloride given the survival benefit in metastatic prostate cancer patients, led to predominant use of this alpha emitter in prostate cancer patients. With rapid development of radiopharmaceutical therapies and approval of other targeted agents such as 177Lu-PSMA the approach to treatment of bone metastasis has further evolved and combination treatments have increasingly been applied. Novel approaches are needed to improve and expand the use of such therapies for treatment of bone metastasis. Combination therapies with different targeting mechanisms, combining chemotherapies and cocktail of alpha and beta emitters need further exploration.

Current state of theranostics in metastatic castrate-resistant prostate cancer

Prostate cancer remains one of the leading causes of cancer-related death in the world. There have been significant advances in chemotherapy, hormonal therapy and targeted therapy options for patients with castrate-resistant disease. However, these systemic treatments are often associated with unwanted toxicities. Targeted therapy with radiopharmaceuticals has become of key interest to limit systemic toxicity and provides a more precision oncology approach to treatment. Strontium-89, Samarium-153 EDTMP and Radium-223 have been trialled with mixed results. Strontium-89 and Samarium-153 EDTMP have shown benefits in palliating metastatic bone pain but with no impact on survival outcomes. Early therapeutic radiopharmaceuticals targeting PSMA that were developed were beta-emitting agents, but recently alpha-emitting agents are being investigated as potentially superior options. Radium-223 is the first alpha-particle emitter therapeutic agent approved by the FDA, with phase III trial evidence showing benefits in overall survival and delay in symptomatic skeletal events for patients. Recently, 177-Lutetium-PSMA-617 has demonstrated significant survival advantages in pre-treated metastatic castrate-resistant cancer patients in a number of phase II and III studies. Furthermore, 225-Actinium-PSMA-617 also showed promise even in patients pre-treated with 177-Lutetium-PSMA-617. Hence, there has been an explosion of radiopharmaceutical treatment options for patients with prostate cancer. This review explores past and current theranostic capacities in the radiopharmaceutical treatment of metastatic castrate-resistant prostate cancer.

Outcomes and patterns of use of Radium-223 in metastatic castration-resistant prostate cancer

Introduction

Radium-223 dichloride (Ra-223) is recommended as a treatment option for metastatic castration-resistant prostate cancer (mCRPC) patients with symptomatic bone metastases and no visceral disease, after docetaxel failure, or in patients who are not candidates to receive it. In this study, we aimed to ambispectively analyze overall survival (OS) and prognostic features in mCRPC in patients receiving Ra-223 as per clinical routine practice and identify the most suitable treatment sequence.

Patients and methods

This study is observational, multicentric, and ambispective. Eligibility criteria included mCRPC patients treated with Ra-223, with an Eastern Cooperative Oncology Group (ECOG) performance status of 0-2, without visceral metastases, and no more than three cm involved lymph nodes.

Results

A total of 145 patients were included; the median age was 73.97 years, and a Gleason score of more than or equal to 7 in 61 (48%) patients; 73 (81%) had previously received docetaxel. The most important benefit was reached by those patients who received Ra-223 in the second-line setting, with a median OS of 17 months (95% CI, 12-21), and by patients who received six cycles of treatment, with a median OS of 19 months (95% CI, 14-21). An alkaline phosphatase (ALP) decrease was also identified as a prognosis marker. When performing the multivariate analysis, the time to develop castration-resistant disease longer than 24 months was the most important prognostic factor to predict the evolution of the patients receiving Ra-223. Ra-223 was well tolerated, with thrombocytopenia, anemia, and diarrhea being the main adverse events.

Conclusion

There is a benefit for those patients who received Ra-223 in the second-line setting, regardless of prior use of docetaxel. In addition, a survival benefit for patients presenting with a decline in ALP was observed.

Clinical Management of Advanced Prostate Cancer: Where Does Radiopharmaceutical Therapy Fit in the Treatment Algorithm?

Most men with newly appreciated metastatic prostate cancer are optimally treated with a backbone consisting of androgen receptor-directed therapy with or without taxane chemotherapy. Despite improvements in disease outcomes, prostate cancer remains an extremely heterogeneous disease with variable mechanisms of therapeutic resistance. As a result, it remains a leading cause of cancer-related death in men. Radiopharmaceutical therapy has emerged as an alternative, non-androgen receptor-directed treatment modality for metastatic castration-resistant prostate cancer that impacts patient survival and represents a potentially more personalized approach. In this review, we aim to outline the current treatment landscape for metastatic prostate cancer with a focus on radiopharmaceutical therapy, specifically 177Lu-PSMA-617. In addition, we illustrate various clinical challenges with 177Lu-PSMA-617 treatment to date and explore investigative efforts to leverage radiopharmaceutical therapies as part of combination regimens or earlier in the treatment algorithm to further improve patient outcomes. Finally, we introduce ongoing studies of alternative radiopharmaceutical therapies in metastatic prostate cancer that may be incorporated into the treatment algorithm pending further study.

ISIT-QA: In Silico Imaging Trial to Evaluate a Low-Count Quantitative SPECT Method Across Multiple Scanner-Collimator Configurations for 223Ra-Based Radiopharmaceutical Therapies

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 223Ra-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 223Ra-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 223RaCl2 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 223Ra-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.

Evaluating first-line therapeutic strategies for metastatic castration-resistant prostate cancer: a comprehensive network meta-analysis and systematic review

Objective

This study aimed to evaluate the relative efficacy and safety of first-line treatment options for metastatic castration-resistant prostate cancer (mCRPC).

Methods

We systematically searched electronic databases, including PubMed and Web of Science, for studies published from their inception to April 3rd, 2023. Inclusion criteria were: 1) Completed Phase III or IV randomized controlled trials (RCTs) registered on ClinicalTrials.gov; 2) Patients with a confirmed diagnosis of mCRPC who had not previously received chemotherapy or novel endocrine therapies. We conducted a network meta-analysis using R software (version 3.4.0). Network graphs and risk of bias graphs were generated using Stata 14.0 and RevMan 5.4, respectively. The primary outcome was overall survival (OS), and the secondary outcome was the incidence of severe adverse events (SAEs).

Results

Seven RCTs encompassing 6,641 patients were included. The network meta-analysis revealed that both docetaxel+prednisone (DP) and cabazitaxel+prednisone (CP) significantly improved OS compared to abiraterone. Compared to placebo, DP showed comparable results to both cabazitaxel 20 mg/m^2+prednisone (C20P) and cabazitaxel 25 mg/m^2+prednisone (C25P) in terms of OS. For SAEs, both DP and C20P were superior to C25P, with no statistical difference between C20P and DP. The probability ranking plots indicated that C25P ranked highest for OS, while DP ranked highest for SAEs.

Conclusions

Based on our network meta-analysis, we recommend cabazitaxel 20 mg/m^2+prednisone (C20P) as the primary choice for first-line management of mCRPC, followed by DP. Enzalutamide and abiraterone are suggested as subsequent options. Radium-223 may be considered for patients presenting with bone metastases.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42023443943.

Combining theranostic/particle therapy with immunotherapy for the treatment of GU malignancies

Particle therapy and radiopharmaceuticals are emerging fields in the treatment of genitourinary cancers. With these novel techniques and the ever-growing immunotherapy options, the combinations of these therapies have the potential to improve current cancer cure rates. However, the most effective sequence and combination of these therapies is unknown and is a question that is actively being explored in multiple ongoing clinical trials. Here, we review the immunological effects of particle therapy and the available radiopharmaceuticals and discuss how best to combine these therapies.

Theranostics revolution in prostate cancer: Basics, clinical applications, open issues and future perspectives

In the last years, theranostics has expanded the therapeutic options available for prostate cancer patients. In this review, we explore this dynamic field and its potential to revolutionize precision medicine for prostate cancer. We delve into the foundational principles, clinical applications, and emerging opportunities, emphasizing the potential synergy between radioligand therapy and other systemic treatments. Additionally, we address the ongoing challenges, including optimizing patient selection, assessing treatment responses, and determining the role of theranostics within the broader landscape of prostate cancer treatment.

Radiotheranostics in advanced prostate cancer: Current and future directions

The discovery of small molecules that target the extracellular domain of prostate-specific membrane antigen (PSMA) has led to advancements in diagnostic imaging and the development of precision radiopharmaceutical therapies. In this review, we present the available existing data and highlight the key ongoing clinical evaluations of PSMA-based imaging in the management of primary, biochemically recurrent, and metastatic prostate cancer. We also discuss clinical studies that explore the use of PSMA-based radiopharmaceutical therapy (RPT) in metastatic prostate cancer and forthcoming trials that investigate PSMA RPT in earlier disease states. Multidisciplinary collaboration in clinical trial design and therapeutic administration is critical to the continued progress of this evolving radiotheranostics field.

Contemporary Systemic Therapy Intensification for Prostate Cancer: A Review for General Practitioners in Oncology

Prostate cancer accounts for a significant proportion of cancer diagnoses in Canadian men. Over the past decade, the therapeutic landscape for the management of metastatic prostate cancer has undergone rapid changes. Novel strategies use hormonal agents, chemotherapy, homologous recombination repair inhibitors, and radioligand therapy or combination strategies in addition to androgen deprivation therapy. In this review, we summarize the available data addressing key therapeutic areas along the disease continuum and focus on practical aspects for general practitioners in oncology managing patients with metastatic prostate cancer.

The Potential Contribution of Radiopharmaceutical Therapies in Managing Oligometastatic Disease

There is a growing understanding of the oligometastatic disease state, characterized by the presence of 5 or fewer lesions. Advanced molecular imaging techniques, such as prostate-specific membrane antigen PET, refines the ability to detect oligometastatic recurrences (oligorecurrences) early. These developments have led to the exploration of metastasis-directed therapy (MDT) in oligorecurrent disease as an alternative to or as a means of delaying systemic therapy. Unfortunately, MDT often does not provide a durable cure, and progression-particularly progression in multiple new areas-remains a concern. Simultaneously, developments in radioligand therapy (RLT) have led to studies showing overall survival benefits with α-emitting and β-emitting RLT in advanced, high-volume, metastatic castration-resistant prostate cancer. The success of RLT in late-stage disease suggests that earlier use in the disease spectrum may be impactful. Specifically, integration of RLT with MDT might reduce progression, including polymetastatic progression, in the setting of oligorecurrent disease.

A Case of Success: Complete Response to Radium-223 in Metastatic Castration-Resistant Prostate Cancer

Radium-223 dichloride (Ra223) is the first targeted alpha agent approved for treating metastatic castration-resistant prostate cancer (mCRPC) with bone-exclusive disease. A benefit in overall survival and time to the first symptomatic skeletal-related event was shown in the Alpharadin in Symptomatic Prostate Cancer Patients (ALSYMPCA) trial. However, this trial did not describe a bone scan response to Ra223, and there is no universal consensus about how it should be monitored. Furthermore, a scintigraphy flare phenomenon may lead to false-positive tracer uptake in responsive cases, thereby misleading the interpretation of imaging results.  We present the case of a 67-year-old male with mCRPC and exclusive bone disease treated with Ra223. The bone scintigraphy after the end of the treatment showed an apparent aggravation of the lesions, corresponding to a flare phenomenon, with an almost complete resolution after three months. The patient maintained a scintigraphic response for seven months.

Novel Therapeutic Targets on the Horizon: An Analysis of Clinical Trials on Therapies for Bone Metastasis in Prostate Cancer

In the absence of early detection and initial treatment, prostate cancer often progresses to an advanced stage, frequently spreading to the bones and significantly impacting patients' well-being and healthcare resources. Therefore, managing patients with prostate cancer that has spread to the bones often involves using bone-targeted medications like bisphosphonates and denosumab to enhance bone structure and minimize skeletal complications. Additionally, researchers are studying the tumor microenvironment and biomarkers to understand the mechanisms and potential treatment targets for bone metastases in prostate cancer. A literature search was conducted to identify clinical studies from 2013 to 2023 that focused on pain, performance status, or quality of life as primary outcomes. The analysis included details such as patient recruitment, prior palliative therapies, baseline characteristics, follow-up, and outcome reporting. The goal was to highlight the advancements and trends in bone metastasis research in prostate cancer over the past decade, with the aim of developing strategies to prevent and treat bone metastases and improve the quality of life and survival rates for prostate cancer patients.

[Metastatic castration-resistant prostate cancer-what are rational sequential treatment options?]

BACKGROUND

In advanced prostate cancer, disease progression during ongoing androgen deprivation therapy (ADT) is referred to as castration-resistant prostate cancer (CRPC). Various therapeutic modalities are available for its treatment, including endocrine therapy, chemotherapy, poly (ADP-ribose) polymerase [PARP] inhibition, radionuclide therapy, and radioligand therapy.

OBJECTIVES

This review outlines practical aspects and considerations regarding treatment sequencing in mCRPC.

MATERIALS AND METHODS

The findings are based on existing prospective phase 3 studies that have demonstrated clinically relevant and statistically significant benefits in radiographically progression-free and/or overall survival.

RESULTS

Sequential therapy, aside from numerous patient-specific factors, depends on the treatment patients received in the hormone-sensitive prostate cancer (mHSPC) setting. Following pretreatment with ADT alone or ADT plus docetaxel in the mHSPC context, additional endocrine therapy is the standard approach. In the event of progression under combined endocrine therapy initiated in the mHSPC setting, docetaxel currently serves as the standard for the majority of patients. Patients who received triplet therapy as a pretreatment in the mHSPC scenario can be treated with radioligand therapy or second-line chemotherapy.

CONCLUSION

Various active and well-tolerated treatment options are available for patients with metastatic castration-resistant prostate cancer (mCRPC). The choice of therapy is primarily determined by previous treatments, but many other individual factors are also taken into consideration.

Alpha Particle-Emitting Radiopharmaceuticals as Cancer Therapy: Biological Basis, Current Status, and Future Outlook for Therapeutics Discovery

Critical advances in radionuclide therapy have led to encouraging new options for cancer treatment through the pairing of clinically useful radiation-emitting radionuclides and innovative pharmaceutical discovery. Of the various subatomic particles used in therapeutic radiopharmaceuticals, alpha (α) particles show great promise owing to their relatively large size, delivered energy, finite pathlength, and resulting ionization density. This review discusses the therapeutic benefits of α-emitting radiopharmaceuticals and their pairing with appropriate diagnostics, resulting in innovative "theranostic" platforms. Herein, the current landscape of α particle-emitting radionuclides is described with an emphasis on their use in theranostic development for cancer treatment. Commonly studied radionuclides are introduced and recent efforts towards their production for research and clinical use are described. The growing popularity of these radionuclides is explained through summarizing the biological effects of α radiation on cancer cells, which include DNA damage, activation of discrete cell death programs, and downstream immune responses. Examples of efficient α-theranostic design are described with an emphasis on strategies that lead to cellular internalization and the targeting of proteins involved in therapeutic resistance. Historical barriers to the clinical deployment of α-theranostic radiopharmaceuticals are also discussed. Recent progress towards addressing these challenges is presented along with examples of incorporating α-particle therapy in pharmaceutical platforms that can be easily converted into diagnostic counterparts.

Precision strikes: PSMA-targeted radionuclide therapy in prostate cancer - a narrative review

Introduction

Radio-ligand targeted therapy is a new and promising concept of treatment Castration resistant prostate cancer (CRPC). Only a few radio-pharmaceutics were approved for usage in treating prostate cancer, among the multiple others tested. We aimed to review and summarize the literature on the therapeutic isotopes specific for PSMA.

Methods

We performed a scoping literature review of PubMed from January 1996 to December 2022.

Results

98 publications were selected for inclusion in this review. The studies contained in publications allowed to summarize the data on pharmacokinetics, therapeutic effects, side effects and the medical use of 225Ac and 177Lu radionuclides. The review also presents new research directions for specific PSMA radionuclides.

Conclusion

Radioligand targeted therapy is a new and promising concept where Lu-177-PSMA-617 have promising outcomes in treatment according to standard of care.

The Curies' element: state of the art and perspectives on the use of radium in nuclear medicine

BACKGROUND

The alpha-emitter radium-223 (223Ra) is presently used in nuclear medicine for the palliative treatment of bone metastases from castration-resistant prostate cancer. This application arises from its advantageous decay properties and its intrinsic ability to accumulate in regions of high bone turnover when injected as a simple chloride salt. The commercial availability of [223Ra]RaCl2 as a registered drug (Xofigo®) is a further additional asset.

MAIN BODY

The prospect of extending the utility of 223Ra to targeted α-therapy of non-osseous cancers has garnered significant interest. Different methods, such as the use of bifunctional chelators and nanoparticles, have been explored to incorporate 223Ra in proper carriers designed to precisely target tumor sites. Nevertheless, the search for a suitable scaffold remains an ongoing challenge, impeding the diffusion of 223Ra-based radiopharmaceuticals.

CONCLUSION

This review offers a comprehensive overview of the current role of radium radioisotopes in nuclear medicine, with a specific focus on 223Ra. It also critically examines the endeavors conducted so far to develop constructs capable of incorporating 223Ra into cancer-targeting drugs. Particular emphasis is given to the chemical aspects aimed at providing molecular scaffolds for the bifunctional chelator approach.

Bone-modifying agents are protective for symptomatic skeletal events in Radium-223 treatment

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.

Theranostic Nuclear Medicine with Gallium-68, Lutetium-177, Copper-64/67, Actinium-225, and Lead-212/203 Radionuclides

Molecular changes in malignant tissue can lead to an increase in the expression levels of various proteins or receptors that can be used to target the disease. In oncology, diagnostic imaging and radiotherapy of tumors is possible by attaching an appropriate radionuclide to molecules that selectively bind to these target proteins. The term "theranostics" describes the use of a diagnostic tool to predict the efficacy of a therapeutic option. Molecules radiolabeled with γ-emitting or β+-emitting radionuclides can be used for diagnostic imaging using single photon emission computed tomography or positron emission tomography. Radionuclide therapy of disease sites is possible with either α-, β-, or Auger-emitting radionuclides that induce irreversible damage to DNA. This Focus Review centers on the chemistry of theranostic approaches using metal radionuclides for imaging and therapy. The use of tracers that contain β+-emitting gallium-68 and β-emitting lutetium-177 will be discussed in the context of agents in clinical use for the diagnostic imaging and therapy of neuroendocrine tumors and prostate cancer. A particular emphasis is then placed on the chemistry involved in the development of theranostic approaches that use copper-64 for imaging and copper-67 for therapy with functionalized sarcophagine cage amine ligands. Targeted therapy with radionuclides that emit α particles has potential to be of particular use in late-stage disease where there are limited options, and the role of actinium-225 and lead-212 in this area is also discussed. Finally, we highlight the challenges that impede further adoption of radiotheranostic concepts while highlighting exciting opportunities and prospects.

Systemic Therapies for Metastatic Castration-Resistant Prostate Cancer: An Updated Review

The introduction of novel therapeutic agents for advanced prostate cancer has led to a wide range of treatment options for patients with metastatic castration-resistant prostate cancer (mCRPC). In the past decade, new treatment options for mCRPC, including abiraterone, enzalutamide, docetaxel, cabazitaxel, sipuleucel-T, radium-223, 177Lu-PSMA-617, and Olaparib, have demonstrated a survival benefit in phase 3 trials. Bone-modifying agents have become part of the overall treatment strategy for mCRPC, in which denosumab and zoledronic acid reduce skeletal-related events. Recently, androgen receptor-signaling inhibitors (ARSIs) and docetaxel have been used upfront against metastatic castration-sensitive prostate cancer. Further, triplet therapy with ARSI, docetaxel, and androgen deprivation therapy is emerging. However, cross-resistance may occur between these treatments, and the optimal treatment sequence must be considered. The sequential administration of ARSIs, such as abiraterone and enzalutamide, is associated with limited efficacy; however, cabazitaxel is effective for patients with mCRPC who were previously treated with docetaxel and had disease progression during treatment with ARSI. Radioligand therapy with 177Lu-PSMA-617 is a new effective class of therapy for patients with advanced PSMA-positive mCRPC. Tumors with gene alterations that affect homologous recombination repair, such as BRCA1 and BRCA2 alterations, are sensitive to poly (adenosine diphosphate-ribose) polymerase (PARP) inhibitors in mCRPC. This review sought to highlight recent advances in systemic therapy for mCRPC and strategies to support patient selection and treatment sequencing.

Prognostic biomarkers in the use of radium-223 in patients with metastatic castration-resistent prostate cancer

OBJECTIVES

This study aimed to establish basal biomarkers in patients with bone metastatic castration-resistant prostate cancer (mCRPC) treated with 223Ra to predict better overall survival (OS), and assess hematologic toxicity and treatment response.

MATERIALS AND METHODS

This was a retrospective multicenter study including 151 patients with mCRPC between 2013 and 2020. OS was assessed according to basal hemoglobin (Hb), prostate-specific antigen (PSA), and alkaline phosphatase (AP) values, the World Health Organization pain scale, the Eastern Cooperative Oncology Group (ECOG) performance status scale, the number of metastatic lesions on bone scintigraphy (BS), and the use of protective bone agents and the dose received. The grade of hematological toxicities was evaluated as well as treatment response based on changes in AP and pre- and post-treatment pain.

RESULTS

The median OS was 24 months (95% confidence interval 16.5-31). The OS in 70% of patients who received complete (5-6 doses) versus incomplete (1-4 doses) 223Ra treatment was 34.9 vs. 5.8 months, respectively, being longer in patients with lower PSA and AP values, Hb >13 g/dl, lesser bone metastasis on bone scan and with an ECOG 0-1. 52/151 patients (34%) died during follow-up. Pain reduced in nearly 70% of patients and 66% presented a reduction in AP values. Half of the patients presented mild and 5 % severe hematological adverse effects.

CONCLUSIONS

mCRPC patients treated with 223Ra with Hb values >13 g/mL, an ECOG 0-1, low AP values, PSA < 20 ng/mL and lesser bone metastasis on BS presented a better OS with an adequate safety profile.

Zoledronic Acid Prevents Bone Resorption Caused by the Combination of Radium-223, Abiraterone Acetate, and Prednisone in an Intratibial Prostate Cancer Mouse Model

An increased risk of non-pathological fractures in patients with prostate cancer and bone metastases has been associated with combination treatment with radium-223, abiraterone, and prednisone/prednisolone in the absence of bone-protecting agents. Here, we investigated possible mechanisms leading to this outcome using an intratibial LNCaP model mimicking prostate cancer bone metastases. Male NOD.scid mice were inoculated intratibially with LNCaP prostate cancer cells and treated with vehicle, radium-223, abiraterone, prednisone, zoledronic acid, or their combinations for 28 days. Serum TRACP 5b and PSA levels were measured. Bone structure, quality, and formation rate of non-tumor-bearing and tumor-bearing tibiae were analyzed by microCT, 3-point bending assay, and dynamic histomorphometry, respectively. Radium-223 incorporation into bone was also measured. Radium-223/abiraterone/prednisone combination treatment induced a transient increase in bone resorption indicated by elevated TRACP 5b levels, which was inhibited by concurrent treatment with zoledronic acid. Furthermore, radium-223/abiraterone/prednisone combination reduced periosteal and trabecular new bone formation and the number of osteoblasts, but bone structure or biomechanical quality were not affected. The abiraterone/prednisone treatment decreased radium-223 incorporation into tumor-bearing bone, possibly explaining the lack of additional antitumor efficacy. In conclusion, radium-223/abiraterone/prednisone combination increased bone resorption, which may have been one of the mechanisms leading to an increased fracture risk in patients with mCRPC.

Novel radionuclide therapy combinations in prostate cancer

Prostate cancer remains the commonest cancer diagnosed in males and a leading cause of cancer-related death. Men with metastatic castration-resistant prostate cancer (mCRPC) who have progressed on chemotherapy and androgen receptor pathway inhibitors (ARPI) have limited treatment options, significant morbidity, and poor outcomes. Prostate-specific membrane antigen (PSMA)-directed radionuclide therapy (RNT) is emerging as an efficacious and well-tolerated therapy; however, disease progression is universal. Several ongoing RNT trials focus on combination strategies to improve efficacy and durability of treatment response, including combinations with ARPIs, chemotherapy, immunotherapy, and targeted therapies. Further, efforts are underway to expand the role of PSMA-directed RNT to earlier stages of disease including hormone-sensitive and localized prostate cancer. In this review, we discuss the rationale and ongoing RNT combination therapeutic trials in prostate cancer and summarize the efficacy and toxicity associated with RNT.

Analysis of the adequacy of control arms in oncology randomised clinical trials published between 2017 and 2021: a meta-research study

INTRODUCTION

Randomised controlled trials (RCTs) are usually considered the highest level of evidence for clinical practice. Patients assigned to control arm in RCTs should always receive the best available treatments to protect participants while also allowing for proper interpretation and applicability of study results. Here we analysed RCTs published in oncology between 2017 and 2021 to describe the frequency of suboptimal control arms.

METHODS

We identified phase III studies testing active treatments in patients with solid tumours among 11 major oncology journals. Each control arm was analysed, and the standard of care was determined according to international guidelines and scientific evidence at accrual beginning and until accrual completion. We identified studies with suboptimal control arm from the beginning (type 1) and studies with an initially optimal control arm which became outdated during the accrual period (type 2).

RESULTS

This analysis included 387 studies. Forty-three (11.1%) control arms were judged as suboptimal: 24 (6.2%) type 1 and 19 (4.9%) type 2. These rates were higher in industry-sponsored compared to academic trials: 9.3% versus 1.9% for type 1 (p = 0.003); 7.9% versus 0.6% for type 2 (p = 0.001). Rates of suboptimal control arms were higher in studies with positive results: 8.1% versus 4.0% for type 1 (p = 0.09); 7.6% versus 1.7% for type 2 (p = 0.007).

CONCLUSIONS

Many trials have suboptimal control arms, even in journals with high-impact factors, leading to suboptimal treatment of control patients and biased evaluation of trial results.

Sarcopenia in Men With Bone-Predominant Metastatic Castration-Resistant Prostate Cancer Undergoing Ra-223 Therapy

INTRODUCTION

Osteosarcopenia is the progressive loss of musculoskeletal structure and functionality, contributing to disability and mortality. Despite complex interactions between bone and muscle, osteosarcopenia prevention and treatment in men with metastatic castration-resistant prostate cancer (mCRPC) focuses predominantly on bone health. It is unknown whether Radium-223 (Ra-223) therapy affects sarcopenia.

METHODS

We identified 52 patients with mCRPC who had received Ra-223 and had a baseline plus ≥1 follow-up abdominopelvic CT scan. The total contour area (TCA) and averaged Hounsfield units (HU) of the left and right psoas muscles were obtained at the inferior L3 endplate, and the psoas muscle index (PMI) was calculated therefrom. Intrapatient musculoskeletal changes were analyzed across various time points.

RESULTS

TCA and PMI gradually declined over the study period (P = .002, P = .003, respectively), but Ra-223 therapy did not accelerate sarcopenia, nor the decline of HU compared to the pre-Ra-223 period. The median overall survival of patients with baseline sarcopenia was numerically worse (14.93 vs. 23.23 months, HR 0.612, P = .198).

CONCLUSIONS

Ra-223 does not accelerate sarcopenia. Thus, worsening muscle parameters in men with mCRPC undergoing Ra-223 therapy are attributable to other factors. Further research is needed to determine whether baseline sarcopenia predicts poor overall survival in such patients.

Enzalutamide Prior to Radium-223 Is Associated with Better Overall Survival in Metastatic Castration-Resistant Prostate Cancer Patients Compared to Abiraterone-A Retrospective Study

Metastatic castration-resistant prostate cancer (mCRPC) is a progressive stage of prostate cancer that often spreads to the bone. Radium-223, a bone-targeting radiopharmaceutical, has been shown to improve the overall survival in mCRPC in patients without visceral metastasis. However, the impact of prior systemic therapy on the treatment outcome of mCRPC patients receiving radium-223 remains unclear. This study aimed to investigate the optimal choice of systemic therapy before radium-223 in mCRPC patients. The study included 41 mCRPC patients who received radium-223 therapy, with 22 receiving prior enzalutamide and 19 receiving prior abiraterone. The results showed that the median overall survival was significantly longer in the enzalutamide group than in the abiraterone group (25.1 months vs. 14.8 months, p = 0.049). Moreover, the number of patients requiring blood transfusion was higher in the abiraterone group than in the enzalutamide group (9.1% vs. 26.3%, p = 0.16). The study also found that the number of doses of Radium-223 received was significantly associated with overall survival (≥5 vs. <5, HR 0.028, 95%CI 0.003-0.231, p = 0.001). Our study provides insights into the optimal treatment choice for mCRPC prior to radium-223, indicating that enzalutamide prior to radium-223 administration may have better outcomes compared to abiraterone in mCRPC patients without visceral metastasis.

Metastatic Castration-Resistant Prostate Cancer: Insights on Current Therapy and Promising Experimental Drugs

The therapeutic landscape of metastatic hormone sensitive and metastatic castration-resistant prostate cancer (mCRPC) is rapidly changing. We reviewed the current treatment options for mCRPC, with insights on new available therapeutic strategies. Chemotherapy with docetaxel or cabazitaxel (for patients progressing on docetaxel), as well as treatment with androgen receptor axis targeted therapies, and Radium-223 are well-established treatment options for patients with mCRPC. The advent of theragnostic in prostate cancer established Lutetium-177 (177Lu)-PSMA-617 as a new standard of care for PSMA-positive mCRPC previously treated with ARAT and taxane-based chemotherapy. Olaparib, a poly-ADP-ribose polymerase (PARP) inhibitor, is approved for selected patients with mCRPC progressed on ARATs and in combination with abiraterone acetate as first-line treatment for mCRPC. Immunotherapy showed limited efficacy in unselected patients with mCRPC and novel immunotherapy strategies need to be explored. The search for biomarkers is a growing field of interest in mCRPC, and predictive biomarkers are needed to support the choice of treatment and the development of tailored strategies.

Innovation in Radionuclide Therapy for the Treatment of Prostate Cancers: Radiochemical Perspective and Recent Therapeutic Practices

Prostate cancer represents the second cause of death by cancer in males in western countries. While early-stage diseases are accessible to surgery and/or external radiotherapy, advanced metastatic prostate cancers are primarily treated with androgen deprivation therapy, to which new generation androgen receptor antagonists or taxane-based chemotherapies are added in the case of tumor relapse. Nevertheless, patients become invariably resistant to castration with a median survival that rarely exceeds 3 years. This fostered the search for alternative strategies, independent of the androgen receptor signaling pathway. In this line, radionuclide therapies may represent an interesting option as they could target either the microenvironment of sclerotic bone metastases with the use of radiopharmaceuticals containing samarium-153, strontium-89 or radium-223 or tumor cells expressing the prostate-specific membrane antigen (PSMA), a protein found at the surface of prostate cancer cells. This review gives highlights the chemical properties of radioligands targeting prostate cancer cells and recapitulates the clinical trials evaluating the efficacy of radionuclide therapies, alone or in combination with other approved treatments, in patients with castration-resistant prostate tumors. It discusses some of the encouraging results obtained, especially the benefit on overall survival that was reported with [¹⁷⁷Lu]-PSMA-617. It also addresses the specific requirements for the use of this particular class of drugs, both in terms of medical staff coordination and adapted infrastructures for efficient radioprotection.

Clinical outcomes and treatment patterns in REASSURE: planned interim analysis of a real-world observational study of radium-223 in metastatic castration-resistant prostate cancer

Background

Radium-223, a targeted alpha therapy, is approved to treat bone-dominant metastatic castration-resistant prostate cancer (mCRPC), based on significantly prolonged overall survival versus placebo and a favourable safety profile in the phase 3 ALSYMPCA study. ALSYMPCA was conducted when few other treatment options were available, and prospectively collected data are limited on the use of radium-223 in the current mCRPC treatment landscape. We sought to understand long-term safety and treatment patterns in men who received radium-223 in real-world clinical practice.

Methods

REASSURE (NCT02141438) is a global, prospective, observational study of radium-223 in men with mCRPC. Primary outcomes are adverse events (AEs), including treatment-emergent serious AEs (SAEs) and drug-related AEs during and ≤30 days after radium-223 completion, grade 3/4 haematological toxicities ≤6 months after last radium-223 dose, drug-related SAEs after radium-223 therapy completion, and second primary malignancies.

Findings

Data collection commenced on Aug 20, 2014, and the data cutoff date for this prespecified interim analysis was Mar 20, 2019 (median follow-up 11.5 months [interquartile range 6.0-18.6]), 1465 patients were evaluable. For second primary malignancies, 1470 patients were evaluable, 21 (1%) of whom had a total of 23 events. During radium-223 therapy, 311 (21%) of 1465 patients had treatment-emergent SAEs, and 510 (35%) had drug-related AEs. In the 6 months after completion of radium-223 therapy, 214 (15%) patients had grade 3/4 haematological toxicities. Eighty patients (5%) had post-treatment drug-related SAEs. Median overall survival was 15.6 months (95% confidence interval 14.6-16.5) from radium-223 initiation. Patient-reported pain scores declined or stabilised. Seventy (5%) patients had fractures.

Interpretation

REASSURE offers insight into radium-223 use in global real-world clinical practice with currently available therapies. At this interim analysis, with a median follow-up of almost 1 year, 1% of patients had second primary malignancies, and safety and overall survival findings were consistent with clinical trial experience. Final analysis of REASSURE is due in 2024.

Funding

Bayer HealthCare.

Management of bone metastasis in prostate cancer

Progression of bone metastases is the primary cause of death in prostate cancer, and skeletal-related events (SREs), including pathologic fractures, spinal cord compression, radiation, or surgery to bone can impair patients' quality of life. Over the past decade, the development of cytotoxic agents, androgen-receptor-axis-targeted therapies (ARATs), and radioligand therapies has prolonged overall survival of prostate cancer patients with bone metastases and reduced the risk of SREs. The use of bone-modifying agents has also contributed to the reduced risk of SREs. Initial use of a cytotoxic agent, docetaxel, or an ARAT agent with androgen deprivation therapy (ADT) is the current approach to metastatic castration-sensitive prostate cancer. However, there is no consensus on the optimal medication for upfront use in combination with ADT, or on specific patient selection. Recently, next-generation imaging modalities, such as whole-body magnetic resonance imaging and prostate-specific membrane antigen-positron emission tomography have been utilized to detect bone metastases at an early stage. In addition, metastasis-directed therapy, such as stereotactic body radiation therapy, has been attempted. In the future, patients with bone metastatic prostate cancer will be divided into subgroups and their treatment options will be tailored to their specific characteristics.

Clinical Translation of Targeted α-Therapy: An Evolution or a Revolution?

The field of radioligand therapy has advanced greatly in recent years, driven largely by β-emitting therapies targeting somatostatin receptor-expressing tumors and the prostate-specific membrane antigen. Now, more clinical trials are under way to evaluate α-emitting targeted therapies as potential next-generation theranostics with even higher efficacy due to their high linear energy and short range in human tissues. In this review, we summarize the important studies ranging from the first Food and Drug Administration-approved α-therapy, ²²³Ra-dichloride, for treatment of bone metastases in castration-resistant prostate cancer, including concepts in clinical translation such as targeted α-peptide receptor radiotherapy and ²²⁵Ac-PSMA-617 for treatment of prostate cancer, innovative therapeutic models evaluating new targets, and combination therapies. Targeted α-therapy is one of the most promising fields in novel targeted cancer therapy, with several early- and late-stage clinical trials for neuroendocrine tumors and metastatic prostate cancer already in progress, along with significant interest and investment in additional early-phase studies. Together, these studies will help us understand the short- and long-term toxicity of targeted α-therapy and potentially identify suitable therapeutic combination partners.

Bone Metastases and Health in Prostate Cancer: From Pathophysiology to Clinical Implications

Clinically relevant bone metastases are a major cause of morbidity and mortality for prostate cancer patients. Distinct phenotypes are described: osteoblastic, the more common osteolytic and mixed. A molecular classification has been also proposed. Bone metastases start with the tropism of cancer cells to the bone through different multi-step tumor-host interactions, as described by the "metastatic cascade" model. Understanding these mechanisms, although far from being fully elucidated, could offer several potential targets for prevention and therapy. Moreover, the prognosis of patients is markedly influenced by skeletal-related events. They can be correlated not only with bone metastases, but also with "bad" bone health. There is a close correlation between osteoporosis-a skeletal disorder with decreased bone mass and qualitative alterations-and prostate cancer, in particular when treated with androgen deprivation therapy, a milestone in its treatment. Systemic treatments for prostate cancer, especially with the newest options, have improved the survival and quality of life of patients with respect to skeletal-related events; however, all patients should be evaluated for "bone health" and osteoporotic risk, both in the presence and in the absence of bone metastases. Treatment with bone-targeted therapies should be evaluated even in the absence of bone metastases, as described in special guidelines and according to a multidisciplinary evaluation.

Treatment outcomes with radium-223 in docetaxel-naïve versus docetaxel-treated metastatic castration-resistant prostate cancer patients: Real-world evidence from Taiwan

While radium (Ra)-223 is among the multiple, known life-prolonging treatments in bone-predominant metastatic castration-resistant prostate cancer (mCRPC), optimal treatment sequencing has not been determined, particularly in the Asia-Pacific context. Hence, we aimed to compare treatment outcomes of docetaxel-naïve and post-docetaxel mCRPC patients undergoing Ra-223 therapy in Taiwan. Using a single-center retrospective cohort design, we reviewed records of adult patients receiving Ra-223 for bone-metastatic mCRPC from 2018 to 2021. Patients were categorized into docetaxel-naïve or post-docetaxel groups based on history of docetaxel use preceding Ra-223. We compared the 2 groups in terms of all-cause death, 6-cycle treatment completion, and the following secondary outcomes: pain control, change in biochemical parameters (prostate-specific antigen, lactate dehydrogenase, alkaline phosphatase), biochemical response, and treatment-emergent adverse events. We performed total population sampling and a complete case analysis. We included 48 patients (25 docetaxel-naïve, 23 post-docetaxel) in the study. The mean follow-up duration was 12.4 months for the entire cohort. The docetaxel-naïve group exhibited a significantly lower all-cause mortality rate versus the post-docetaxel group (40.0% vs 78.3%, P = .02), as well as a significantly higher treatment completion rate (72.0% vs 26.1%, P < .01). We did not find significant differences in pain control, change in biochemical parameters, biochemical response, or hematologic treatment-emergent adverse events between the 2 groups. However, the docetaxel-naïve group had a numerically higher pain control rate, numerically greater improvements in alkaline phosphatase and prostate-specific antigen, and numerically lower rates of grade ≥ 3 neutropenia and grade ≥ 3 thrombocytopenia than the post-docetaxel group. Use of Ra-223 in docetaxel-naïve patients with mCRPC led to lower mortality and higher treatment completion than post-docetaxel use. Our study adds preliminary real-world evidence that Ra-223 may be used safely and effectively in earlier lines of treatment for bone-predominant mCRPC. Further large-scale, longer-term, and controlled studies are recommended.

Commercial and business aspects of alpha radioligand therapeutics

Radioligand therapy (RLT) is gaining traction as a safe and effective targeted approach for the treatment of many cancer types, reflected by a substantial and growing commercial market (valued at $7.78 billion in 2021, with a projected value of $13.07 billion by 2030). Beta-emitting RLTs have a long history of clinical success dating back to the approval of Zevalin and Bexxar in the early 2000s, later followed by Lutathera and Pluvicto. Alpha radioligand therapeutics (ARTs) offer the potential for even greater success. Driven by ground-breaking clinical results in early trials, improved isotope availability, and better understanding of isotope and disease characteristics, the global market for alpha emitters was estimated at $672.3 million for the year 2020, with projected growth to $5.2 billion by 2027. New company formations, promising clinical trial data, and progression for many radioligand therapy products, as well as an inflow of investor capital, are contributing to this expanding field. Future growth will be fueled by further efficacy and safety data from ART clinical trials and real-world results, but challenges remain. Radionuclide supply, manufacturing, and distribution are key obstacles for growth of the field. New models of delivery are needed, along with cross-disciplinary training of specialized practitioners, to ensure patient access and avoid challenges faced by early RLT candidates such as Zevalin and Bexxar. Understanding of the history of radiation medicine is critical to inform what may be important to the success of ART-most past projections were inaccurate and it is important to analyze the reasons for this. Practical considerations in how radiation medicine is delivered and administered are important to understand in order to inform future approaches.

Effectiveness and safety of radium-223 dichloride in patients with castration-resistant prostate cancer and bone metastases in real-world practice: A multi-institutional study

OBJECTIVE

Radium-223 (Ra-223) dichloride is the bone-targeted radioligand therapy that prolongs overall survival (OS) in patients with bone-metastatic castration-resistant prostate cancer (CRPC). We aimed to evaluate the safety and effectiveness of this treatment in real-world practice.

METHODS

We included Japanese men treated with Ra-223 for bone-metastatic CRPC from 10 institutions, retrospectively. Primary endpoint was OS. Secondary endpoint was maximum decline of alkaline phosphatase (ALP), lactate dehydrogenase, and prostate-specific antigen values, the rate of adverse events, and time to pathological fracture after Ra-223 treatment. Exploratory endpoint was the associations between clinical parameters and OS.

RESULTS

In total, 73 men with bone metastatic CRPC treated with Ra-223 were enrolled. The median OS was 20.9 months. ALP levels decreased significantly from pre-treatment (p = 0.03). Anemia occurred in three (4.1%) patients. Grade ≥ 3 non-pathological fractures occurred in four (5.5%) men. Nine (12.3%) patients presented pathological fracture; 7/30 (23.3%) were in men without concomitant use of a bone-modifying agent (BMA) while 2/43 (4.7%) were in patients with concomitant BMA (p = 0.03). The median OS in patients with ≥3 cycles treatment (27.2 months, p < 0.001) or hemoglobin ≥12 g/dl (27.2 months, p = 0.001) or absence of bone pain (36.3 months, p = 0.004) was significantly longer compared to those who with ≤2 cycles or hemoglobin<12 g/dl or presence of bone paint, respectively.

CONCLUSIONS

This study has shown the outcomes of Ra-223 treatment in real-world practice, where the number of treatment cycles, baseline anemia and bone pain may be useful to predict OS in Ra-223 treatment.

Real World Outcomes in Patients With Metastatic, Castration-Resistant Prostate Cancer Treated With Radium-223 in Routine Clinical Practice in Sweden

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.

Radium-223 dichloride treatment in metastatic castration-resistant prostate cancer in Finland: A real-world evidence multicenter study

BACKGROUND

Radium-233 dichloride is an alpha emitter that specifically targets bone metastases in prostate cancer. Results of a previously reported phase III randomized trial showed survival benefit for radium-223 compared to best supportive care in castration-resistant prostate cancer (CRPC) with bone metastases. However, real-world data are also needed with wider inclusion criteria.

METHODS

We report results of a retrospective multicenter study including all patients with metastatic CRPC treated with radium-223 in all five university hospitals in Finland since the introduction of the treatment. We identified 160 patients who had received radium-223 in Finland in 2014-2019.

RESULTS

The median overall survival (OS) was 13.8 months (range 0.5-57 months), and the median real-world progression-free survival (rwPFS) was 4.9 months (range 0.5-29.8 months). Alkaline phosphatase (ALP) values within the normal range before and during the radium-223 treatment or the reduction of elevated ALP to normal range during treatment were associated with better OS when compared to elevated ALP values before and during treatment (p < 0.0001). High prostate-specific antigen (PSA) level (≥100 μg/L) before radium-223 treatment was associated with poor OS compared to low PSA level (<20 μg/L) (p = 0.0001). Most patients (57%) experienced pain relief. Pain relief indicated better OS (p = 0.002). Radium-223 treatment was well tolerated. Toxicity was mostly low grade. Only 12.5% of the patients had grade III-IV adverse events, most commonly anemia, neutropenia, leucopenia, and thrombocytopenia.

CONCLUSION

Radium-223 was well tolerated in routine clinical practice, and most patients achieved pain relief. Pain relief, ALP normalization, lower baseline PSA, and PSA decrease during radium-223 treatment were prognostic for better survival. The efficacy of radium-223 in mCRPC as estimated using OS was comparable to earlier randomized trial in this retrospective real-world study. Our results support using radium-223 for mCRPC patients with symptomatic bone metastases even in the era of new-generation androgen receptor-targeted agents.