Non-metastatic CRPC and asymptomatic metastatic CRPC: which treatment for which patient?

Physician preferences for nonmetastatic castration-resistant prostate cancer treatment in China

Introduction

The treatment preferences of Chinese physicians who treat nonmetastatic castration-resistant prostate cancer (nmCRPC) and how they weigh the benefits and risks of nmCRPC treatment are still unknown. This study aimed to evaluate Chinese physicians' benefit-risk treatment preferences for nmCRPC and assist in setting nmCRPC treatment goals.

Methods

A paper-based discrete choice experiment (DCE) survey was administered to 80 nmCRPC-treating physicians. DCE responses were analyzed to produce the preference weight and the relative importance score for each attribute level. The marginal rate of substitution (MRS) was used to quantify the amount of overall survival (OS) physicians were willing to trade for a reduction in treatment-related adverse events (AEs). We further conducted the exploratory analysis, stratifying physicians from 5 perspectives into different subgroups and examining the treatment preferences and OS trade-off in each subgroup.

Results

In terms of efficacy attributes, physicians placed greater emphasis on OS than time to pain progression. With regard to safety attributes, serious fracture was perceived as the most important AE by physicians, followed by serious fall, cognitive problems, skin rash, and fatigue. In the exploratory analysis, we found generally that physicians with less clinical practice experience and those from more economically developed regions placed more emphasis on AEs and were willing to give up more of their patients' OS to reduce the risk of AEs.

Conclusion

Physicians from mainland China value the importance of minimizing treatment-related AEs when considering different treatment options for patients with nmCRPC, and they are willing to trade a substantial amount of OS to avoid AEs.

Drug-drug interaction potential among patients with nonmetastatic castration-resistant prostate cancer (nmCRPC) treated with novel androgen receptor inhibitors

BACKGROUND

Nonmetastatic castration-resistant prostate cancer (nmCRPC) patients are often older and use concurrent medications that increase the potential for drug-drug interactions (pDDIs). This study assessed pDDI prevalence in real-world nmCRPC patients treated with apalutamide, darolutamide, or enzalutamide.

RESEARCH DESIGN AND METHODS

Castrated prostate cancer patients without metastases prior to androgen receptor inhibitor initiation were identified retrospectively via Optum Clinformatics Data Mart claims data (8/2019-3/2021). The top 100 concomitant medications were assessed for pDDIs.

RESULTS

Among 1,515 patients (mean age: 77 ± 8 years; mean Charlson Comorbidity Index: 3 ± 3), 340 initiated apalutamide, 112 darolutamide, and 1,063 enzalutamide. Common concomitant medication classes were cardiovascular (80%) and central nervous system (52%). Two-thirds of the patients received ≥5 concomitant medications; 30 (30/100 medications) pDDIs were identified for apalutamide and enzalutamide each and 2 (2/100 medications) for darolutamide. Most pDDIs had risk ratings of C or D, but four for apalutamide were rated X. Approximately 58% of the patients on apalutamide, 5% on darolutamide, and 54% on enzalutamide had ≥1 identified pDDI.

CONCLUSIONS

Results showed a higher frequency of pDDIs in patients receiving apalutamide and enzalutamide vs darolutamide. The impact of these could not be determined retrospectively. DDI risk should be carefully evaluated when discussing optimal therapy for patients with nmCRPC.

Improving the identification of high-risk non-metastatic castration-resistant prostate cancer patients in clinical practice

Non-metastatic castration-resistant prostate cancer (nmCRPC) represents a challenging disease state in prostate cancer care. nmCRPC patients with a high risk of progression to metastatic disease who are identified by a prostate-specific antigen doubling time (PSADT) ≤10 months are eligible for treatment with the novel androgen receptor inhibitors (ARIs), shown to delay disease progression and extend survival. However, nmCRPC is often unexploited in clinical practice due to a lack of standardization in the methodology and in the tools used for its identification. In this article, a group of Urology and Oncology specialists with acknowledged expertise in prostate cancer reviews the state of the art in the management of high-risk nmCRPC patients, identifies gaps and unmet needs, and proposes strategies to optimize the identification of this patient subgroup in the clinical practice and improve their health outcomes.

Targeting CBX3 with a Dual BET/PLK1 Inhibitor Enhances the Antitumor Efficacy of CDK4/6 Inhibitors in Prostate Cancer

The development of castration-resistant prostate cancer (CRPC) is a significant factor that reduces life expectancy among patients with prostate cancer. Previously, it is reported that CDK4/6 inhibitors can overcome the resistance of CRPC to BET inhibitors by destabilizing BRD4, suggesting that the combination of CDK4/6 inhibitors and BET inhibitors is a promising approach for treating CRPC. In this study, candidates that affect the combined antitumor effect of CDK4/6 inhibitors and BET inhibitors on CRPC is aimed to examine. The data demonstrates that CBX3 is abnormally upregulated in CDK4/6 inhibitors-resistant cells. CBX3 is almost positively correlated with the cell cycle in multiple malignancies and is downregulated by BET inhibitors. Mechanistically, it is showed that CBX3 is transcriptionally upregulated by BRD4 in CRPC cells. Moreover, it is demonstrated that CBX3 modulated the sensitivity of CRPC to CDK4/6 inhibitors by binding with RB1 to release E2F1. Furthermore, it is revealed that PLK1 phosphorylated CBX3 to enhance the interaction between RB1 and CBX3, and desensitize CRPC cells to CDK4/6 inhibitors. Given that BRD4 regulates CBX3 expression and PLK1 affects the binding between RB1 and CBX3, it is proposed that a dual BRD4/PLK1 inhibitor can increase the sensitivity of CRPC cells to CDK4/6 inhibitors partially through CBX3.

The key cellular senescence related molecule RRM2 regulates prostate cancer progression and resistance to docetaxel treatment

BACKGROUND

Prostate cancer is a leading cause of cancer-related deaths among men worldwide. Docetaxel chemotherapy has proven effective in improving overall survival in patients with castration-resistant prostate cancer (CRPC), but drug resistance remains a considerable clinical challenge.

METHODS

We explored the role of Ribonucleotide reductase subunit M2 (RRM2), a gene associated with senescence, in the sensitivity of prostate cancer to docetaxel. We evaluated the RRM2 expression, docetaxel resistance, and ANXA1 expression in prostate cancer cell lines and tumour xenografts models. In addition, We assessed the impact of RRM2 knockdown, ANXA1 over-expression, and PI3K/AKT pathway inhibition on the sensitivity of prostate cancer cells to docetaxel. Furthermore, we assessed the sensitivity of prostate cancer cells to the combination treatment of COH29 and docetaxel.

RESULTS

Our results demonstrated a positive association between RRM2 expression and docetaxel resistance in prostate cancer cell lines and tumor xenograft models. Knockdown of RRM2 increased the sensitivity of prostate cancer cells to docetaxel, suggesting its role in mediating resistance. Furthermore, we observed that RRM2 stabilizes the expression of ANXA1, which in turn activates the PI3K/AKT pathway and contributes to docetaxel resistance. Importantly, we found that the combination treatment of COH29 and docetaxel resulted in a synergistic effect, further augmenting the sensitivity of prostate cancer cells to docetaxel.

CONCLUSION

Our findings suggest that RRM2 regulates docetaxel resistance in prostate cancer by stabilizing ANXA1-mediated activation of the PI3K/AKT pathway. Targeting RRM2 or ANXA1 may offer a promising therapeutic strategy to overcome docetaxel resistance in prostate cancer.

AKT1 regulates UHRF1 protein stability and promotes the resistance to abiraterone in prostate cancer

Oncogenic activation of PI3K/AKT signaling pathway, together with epigenetic aberrations are the characters of castration-resistant prostate cancer (CRPC). UHRF1 as a key epigenetic regulator, plays a critical role in prostate cancer (PCa) development, and its expression is positively correlated with the degree of malignancy. In this present study we investigated the potential regulatory mechanism of AKT1 on UHRF1, and further validated the in vitro and in vivo anticancer efficacy of AKT phosphorylation inhibitor MK2206 in combination with abiraterone. Both UHRF1 and p-AKT aberrantly overexpressed in the abiraterone-resistant PCa cells. Further studies revealed that AKT1 protein interacts with UHRF1, and AKT1 directly phosphorylates UHRF1 via the site Thr-210. MK2206 induced UHRF1 protein degradation by inhibiting AKT1-induced UHRF1 phosphorylation, and then reduced the interaction between UHRF1 and deubiquitinase USP7, while promoted the interaction between UHRF1 and E3 ubiquitin protein ligase BTRC. MK2206 significantly promoted the sensitivity of abiraterone-refractory PCa cells and xenografts to abiraterone by decreasing UHRF1 protein level, and reversed the phenotype of NEPC, evently induced cellular senescence and cell apoptosis. Altogether, our present study for the first time revealed a novel molecular mechanism of abiraterone resistance through PI3K/AKT-UHRF1 pathway, and provided a novel therapeutic modality by targeting PI3K/AKT1 to promote the drug sensitivity of abiraterone in PCa patients.

Optimized Therapeutic 177Lu-Labeled PSMA-Targeted Ligands with Improved Pharmacokinetic Characteristics for Prostate Cancer

Clinical trials have shown the significant efficacy of [¹⁷⁷Lu]Lu-PSMA-617 for treating prostate cancer. However, the pharmacokinetic characteristics and therapeutic performance of [¹⁷⁷Lu]Lu-PSMA-617 still need further improvement to meet clinical expectations. The aim of this study was to evaluate the feasibility and therapeutic potential of three novel ¹⁷⁷Lu-labeled ligands for the treatment of prostate cancer. The novel ligands were efficiently synthesized and radiolabeled with non-carrier added ¹⁷⁷Lu; the radiochemical purity of the final products was determined by Radio-HPLC. The specific cell-binding affinity to PSMA was evaluated in vitro using prostate cancer cell lines 22Rv1and PC-3. Blood pharmacokinetic analysis, biodistribution experiments, small animal SPCET imaging and treatment experiments were performed on normal and tumor-bearing mice. Among all the novel ligands developed in this study, [¹⁷⁷Lu]Lu-PSMA-Q showed the highest uptake in 22Rv1 cells, while there was almost no uptake in PC-3 cells. As the SPECT imaging tracer, [¹⁷⁷Lu]Lu-PSMA-Q is highly specific in delineating PSMA-positive tumors, with a shorter clearance half-life and higher tumor-to-background ratio than [¹⁷⁷Lu]Lu-PSMA-617. Biodistribution studies verified the SPECT imaging results. Furthermore, [¹⁷⁷Lu]Lu-PSMA-Q serves well as an effective therapeutic ligand to suppress tumor growth and improve the survival rate of tumor-bearing mice. All the results strongly demonstrate that [¹⁷⁷Lu]Lu-PSMA-Q is a PSMA-specific ligand with significant anti-tumor effect in preclinical models, and further clinical evaluation is worth conducting.

Real-world burden of adverse events for apalutamide- or enzalutamide-treated non-metastatic castration-resistant prostate cancer patients in the United States

Background

Second-generation androgen receptor inhibitors (ARIs) have been associated with adverse events (AEs) such as fatigue, falls, fractures, and rash in non-metastatic castration-resistant prostate cancer (nmCRPC) patients as identified in clinical trials. The objectives of this study were to describe the incidence and management of AEs in patients receiving apalutamide and enzalutamide.

Methods

This retrospective chart review study was conducted in nmCRPC-treating sites in the United States. Patients starting apalutamide or enzalutamide between February 1, 2018 and December 31, 2018 were included and any AEs they experienced were recorded. AEs, including those considered to be of special interest as defined in the pivotal clinical trials of the second-generation ARIs, were analyzed and grouped retrospectively in this study. Detailed chart data (patient demographics, clinical characteristics, treatment history, type of AE, outcomes, and resource utilization) were then collected for a randomly selected subset among patients with ≥1 AE to characterize AEs and their management. Descriptive results were summarized.

Results

Forty-three sites participated in the study. A total of 699 patients were included, of whom 525 (75.1%) experienced ≥1 AE. The most common AEs were fatigue/asthenia (34.3%), hot flush (13.9%), and arthralgia (13.6%). In the subset of 250 patients randomly selected from those who experienced ≥1 AE, patients were primarily White (72.0%), the mean age was 71 years, 86.0% had an Eastern Cooperative Oncology Group score of 0–1 at nmCRPC diagnosis, and the average prostate specific antigen (PSA) value at diagnosis was 23.2 ng/mL. PSA-doubling time < 10 months was chosen as reason to initiate treatment in 40% of patients. The median duration of follow-up was 1.1 years, with 14.4% of patients progressing to metastasis by end of study period. Grade 3–4 and Grade 5 AEs occurred in 14.4 and 0.4% of patients, respectively. Actions taken to manage AEs included AE-directed treatment (38.0%), ARI discontinuation (10.4%), dose reduction (7.6%), and AE-related hospitalization (4.8%).

Conclusions

This study highlights the burden of AEs among nmCRPC patients treated with apalutamide or enzalutamide, providing a relevant real-world benchmark as clinical trial evidence and the treatment landcape for nmCRPC continues to evolve.

Stereotactic Body Radiotherapy for a Sacral Metastasis Clarified by Diffusion-Weighted Whole-Body Imaging With Background Body Signal Suppression in a Patient With Castration-Resistant Prostate Cancer

Diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) is an emerging extended modality of diffusion-weighted imaging for screening malignant lesions in the body. A 70-year-old male was diagnosed with advanced-stage prostate adenocarcinoma with distant metastasis. After hormone therapy, the disease progressed to castration-resistant prostate cancer (CRPC). Serum prostate-specific antigen (PSA) levels increased during androgen deprivation therapy with low serum testosterone levels. 18F-Fluorodeoxyglucose positron emission tomography (FDG-PET) and technetium-99m methylene bone scintigraphy (BS) did not reveal obvious distant metastases; however, we were able to identify distant metastases by DWIBS. We herein report a case in which stereotactic body radiotherapy (SBRT) was performed on target lesions detected by DWIBS and successfully suppressed disease progression.

SPP1 Promotes Enzalutamide Resistance and Epithelial-Mesenchymal-Transition Activation in Castration-Resistant Prostate Cancer via PI3K/AKT and ERK1/2 Pathways

The bottleneck arising from castration-resistant prostate cancer (CRPC) treatment is its high metastasis potential and antiandrogen drug resistance, which severely affects survival time of prostate cancer (PCa) patients. Secreted phosphoprotein 1 (SPP1) is a cardinal mediator of tumor-associated inflammation and facilitates metastasis. In our previous study, we firstly revealed SPP1 was a potential hub signature for predicting metastatic CRPC (mCRPC) development. Herein, we integrated multiple databases to explore the association of SPP1 expression with prognosis, survival, and metastatic levels in CRPC progression and investigated SPP1 expression in PCa tissues and cell lines. Next, PCa cell lines with overexpression or depletion of SPP1 were established to study the effect of SPP1 on enzalutamide sensitivity and adhesion and migration of prostate cancer cell lines and further explore the underlying regulatory mechanisms. Bioinformatics analysis, polymerase chain reaction (PCR), immunohistochemical staining, and western blot results suggested SPP1 upregulation had strong relationship with the malignant progression of CRPC and enzalutamide resistance. SPP1 knockdown enhanced enzalutamide sensitivity and repressed invasion and migration of prostate cancer cells. Importantly, upregulating SPP1 promoted, while silencing SPP1 attenuated epithelial-mesenchymal-transition (EMT). Our results further demonstrated that SPP1 overexpression maintains the activation of PI3K/AKT and ERK1/2 signaling pathways. Overall, our findings unraveled the functional role and clinical significance of SPP1 in PCa progression and help to discover new potential targets against mCRPC.

Long Non-Coding RNA Landscape in Prostate Cancer Molecular Subtypes: A Feature Selection Approach

Prostate cancer is one of the most common malignancies in men. It is characterized by a high molecular genomic heterogeneity and, thus, molecular subtypes, that, to date, have not been used in clinical practice. In the present paper, we aimed to better stratify prostate cancer patients through the selection of robust long non-coding RNAs. To fulfill the purpose of the study, a bioinformatic approach focused on feature selection applied to a TCGA dataset was used. In such a way, LINC00668 and long non-coding(lnc)-SAYSD1-1, able to discriminate ERG/not-ERG subtypes, were demonstrated to be positive prognostic biomarkers in ERG-positive patients. Furthermore, we performed a comparison between mutated prostate cancer, identified as "classified", and a group of patients with no peculiar genomic alteration, named "not-classified". Moreover, LINC00920 lncRNA overexpression has been linked to a better outcome of the hormone regimen. Through the feature selection approach, it was found that the overexpression of lnc-ZMAT3-3 is related to low-grade patients, and three lncRNAs: lnc-SNX10-87, lnc-AP1S2-2, and ADPGK-AS1 showed, through a co-expression analysis, significant correlation values with potentially druggable pathways. In conclusion, the data mining of publicly available data and robust bioinformatic analyses are able to explore the unknown biology of malignancies.

Treatment of nonmetastatic castration-resistant prostate cancer: focus on second-generation androgen receptor inhibitors

BACKGROUND

Nonmetastatic castration-resistant prostate cancer (nmCRPC) is defined as a rising prostate-specific antigen concentration, despite castrate levels of testosterone with ongoing androgen-deprivation therapy or orchiectomy, and no detectable metastases by conventional imaging. Patients with nmCRPC progress to metastatic disease and are at risk of developing cancer-related symptoms and morbidity, eventually dying of their disease. While patients with nmCRPC are generally asymptomatic from their disease, they are often older and have chronic comorbidities that require long-term concomitant medication. Therefore, careful consideration of the benefit-risk profile of potential treatments is required.

METHODS

In this review, we will discuss the rationale for early treatment of patients with nmCRPC to delay metastatic progression and prolong survival, as well as the factors influencing this treatment decision. We will focus on oral pharmacotherapy with the second-generation androgen receptor inhibitors, apalutamide, enzalutamide, and darolutamide, and the importance of balancing the clinical benefit they offer with potential adverse events and the consequential impact on quality of life, physical capacity, and cognitive function.

RESULTS AND CONCLUSIONS

While the definition of nmCRPC is well established, the advent of next-generation imaging techniques capable of detecting hitherto undetectable oligometastatic disease in patients with nmCRPC has fostered debate on the criteria that inform the management of these patients. However, despite these developments, published consensus statements have maintained that the absence of metastases on conventional imaging suffices to guide such therapeutic decisions. In addition, the prolonged metastasis-free survival and recently reported positive overall survival outcomes of the three second-generation androgen receptor inhibitors have provided further evidence for the early use of these agents in patients with nmCRPC in order to delay metastases and prolong survival. Here, we discuss the benefit-risk profiles of apalutamide, enzalutamide, and darolutamide based on the data available from their pivotal clinical trials in patients with nmCRPC.

Prostate Cancer in Latin America: Challenges and Recommendations

Prostate cancer (PCa) is the most frequent tumor among Latin American (LATAM) men. The incidence of de novo metastatic PCa is higher in LATAM than other parts of the world, and demographic changes in the region have increased disease burden. However, region-specific information regarding prevalence, progression, and treatment effectiveness is not currently available for nonmetastatic, castration-resistant PCa (nmCRPC). Nonmetastatic, castration-resistant PCa is a heterogeneous disease with varying potential to develop metastasis with limited treatments available, until recently. New clinical trials with promising results have allowed second-generation antiandrogen drugs to be used as first-line treatments, rendering guidelines outdated. As a result, this panel of experts reviewed the current status and challenges and developed recommendations for nmCRPC diagnosis and management in LATAM. The Americas Health Foundation (AHF) conducted a literature review and identified LATAM scientists and clinicians who have published in the field of PCa since 2012. The AHF convened a panel of 7 chosen experts urologists and medical oncologists from the region. The AHF developed specific questions relating to nmCRPC, which were answered by the experts prior to the multiday meeting. Each narrative was discussed and edited by the panel, through numerous rounds of discussion until a consensus was reached in a final manuscript. The panel proposes specific and realistic recommendations for improving access to diagnosis and management of PCa in LATAM. No treatment has yet shown improvement in overall survival; however, when including metastasis-free survival as an end point, second-generation antiandrogen drugs have emerged as effective treatment options and are currently included as first-line treatment. Although nmCRPC is a specific disease that represents a small percentage of patients with PCa, effective diagnostic and treatment strategies can contribute toward increasing quality of life and survival rates of patients with PCa in LATAM.

Radium-223 in mCPRC patients: a large real-life Italian multicenter study

BACKGROUND

Radium-223 is a targeted alpha-particles therapy approved for the treatment of mCRPC patients with symptomatic bone metastases. To our knowledge we account for the largest cohort of mCRPC patients subjected to Radium-223 treatment in our country. We aim to describe in a real-life setting the largest cohort of mCRPC patients treated with Radium-223 ever taken into consideration.

METHODS

Four hundred and thirty consecutive mCRPC patients were enrolled. Clinical data have been collected at baseline and at the end of the Radium-223 treatment. Furthermore, the overall survival(OS) of our population has been provided.

RESULTS

One hundred fifty-seven patients (36.5%) were still alive at the time of data analysis. A mean number of 4.95±1.6 cycles of Radium-223 was reached by our cohort. 265 patients (61.6%) completed the whole six cycles regimen. The mean follow-up period from the first cycle of Radium-223 to the date of the analysis was 12.7 months. The analysis of patients Annual Incidence Rate (AIR) in relation to the number of Radium-223 cycles received depicting a clear advantage for those patients who completed the whole six administrations planned, with an AIR (AIR=0.32) of much lesser value compared to those that have performed five cycles (AIR =0.98). 165 patients (38.4%) dropped out of treatment for death or disease progression.

CONCLUSIONS

This study offers a cross-section of the clinical performance of Radium-223 treatment in a real-world context, confirming on a large scale the effectiveness of Radium-223 in improving the OS and quality of life, along with the preservation of an excellent safety profile.

Treatment characteristics for nonmetastatic castration-resistant prostate cancer in the United States, Europe and Japan

Aim: We conducted this study to describe nonmetastatic castration-resistant prostate cancer (nmCRPC) patient characteristics and treatment patterns in the US, Europe and Japan. Materials & methods: Descriptive analyses were conducted using the 2015–2017 Ipsos Global Oncology Monitor Database. Results: A total of 2065 (442 in the US, 509 in Europe and 1114 in Japan) patients (median age: 74–80 years; stage III at diagnosis : 38.5%; Eastern Cooperative Oncology Group [ECOG] score ≤1: 79.4%; treated by urologist : 88.4%) were included in the analytic cohort. Luteinizing hormone-releasing hormone agonists and antiandrogens were the most commonly used first regimen treatments. With subsequent nmCRPC regimens their use decreased, while the use of chemotherapy, corticosteroids, androgen synthesis inhibitors and second-generation androgen receptor inhibitors increased. Conclusion: These data represent real-world treatment patterns in nmCRPC.

Primary Radical Prostatectomy or Ablative Radiotherapy as Protective Factors for Patients With mCRPC Treated With Radium-223 Dichloride: An Italian Multicenter Study

BACKGROUND

We investigated, in a real-life setting, the prognostic relevance of previous primary treatment (radical prostatectomy [RP] or external beam radiotherapy [EBRT]) on overall survival for patients with metastatic castration-resistant prostate cancer (mCRPC) treated with radium-223 (²²³Ra).

MATERIALS AND METHODS

In the present multicenter retrospective study, we enrolled 275 consecutive patients. The demographic and clinical data and mCRPC characteristics were recorded and evaluated at baseline and at the end of treatment or progression. ²²³Ra was administered according to the current label authorization until disease progression or unacceptable toxicity. We divided the whole cohort into 2 groups: those who had undergone primary radical prostatectomy or ablative radiotherapy (RP/EBRT) and those who had not received previous primary treatment (NO).

RESULTS

Of the 275 patients, 128 (46.5%) were alive and undergoing monitoring at the last follow-up examination, 103 (37.4%) had stopped treatment because of disease progression or the onset of comorbidities, and 147 (53.5%) had died during the study period. Of the 275 patients, 132 were in the RP/EBRT group (48%), of whom 93 had undergone RP and 76 had undergone ablative EBRT, and 143 patients were in the NO group (52%). The data showed a clear advantage for the patients in the RP/EBRT group compared with those in the NO group, with an estimated median survival of 18 versus 11 months, respectively (P < .001). The results from the multivariate analysis corroborated this trend, with a hazard ratio of 0.7 (P = .0443), confirming the better outcome for the RP/EBRT group.

CONCLUSIONS

Previous radical treatment provides a protective role for patients with mCRPC undergoing ²²³Ra treatment.

Outcomes of pathologically localized high-grade prostate cancer treated with radical prostatectomy

Adjuvant radiation therapy (ART) is recommended without consideration of radical prostatectomy Gleason score (RP GS) for cases with adverse features. We compared the outcomes of pathologically localized high-grade (GS 8-10) prostate cancer (PC) with those of pT3 GS 7 PC.A total of 1585 men who underwent RP between 1995 and 2015 comprised the cohort, which was divided into group 1 (RP GS 7(3 + 4) and pT3; n = 760), group 2 (RP GS 7(4 + 3) and pT3; n = 565), and group 3 (RP GS 8-10 and pT2; n = 260). Biochemical recurrence (BCR), all-cause mortality (ACM), and PC-specific mortality (PCSM) risk were compared among groups using Cox regression and competing risk analysis.At a median follow-up of 58 months (interquartile range: 37-85), 721 men experienced BCR and 84 died (22 due to PC). BCR-free survival rates were lower in group 3 than in group 1 (P < .001); nevertheless, no difference was observed between groups 2 and 3 (P = .638). Furthermore, no difference in ACM was noted among groups. PCSM rates were higher in group 3 than in groups 1 and 2 (P = .001 and P = .005, respectively). This association persisted in multivariate models after adjustment for clinicopathological variables.Patients with RP GS 8-10 and pT2 PC had higher BCR and PCSM rates than those with RP GS 7 and pT3 PC. Localized high-grade PC should be considered in decision-making for ART.

The correlation between metastasis-free survival and overall survival in non-metastatic castration resistant prostate cancer patients from the Medical Data Vision claims database in Japan

Background and purpose: Several recent randomized controlled trials (RCTs) in non-metastatic castration resistant prostate cancer (nmCRPC) have demonstrated a significant improvement in metastasis-free survival (MFS); however, an improvement in overall survival (OS) is not reported yet. Since the surrogacy of MFS to OS has not been formally investigated in nmCRPC in Japan, this study evaluated the correlation between MFS and OS among a nmCRPC population in Japan. Methods: This is a retrospective longitudinal observational cohort study in patients with nmCRPC using the Japanese Medical Data Vision (MDV) database covering over 20 million patients. A total of 1236 patients with CRPC who had no prior medical history of cancer except prostate cancer and no distant metastasis, and who fulfilled PCWG2 criteria, were identified. Following the identification of nmCRPC, patients' medical records were investigated for subsequent events of metastasis and death. Results: The median follow-up time was 24 months. Median MFS was 28 months (95% CI: 24.0 to 33.0 months) and median OS could not be estimated (95% CI: not estimated). There was a statistically significant correlation between MFS and OS (Pearson's correlation coefficient = 0.62; 95% CI: 0.58-0.65; p < .0001, Spearman's correlation coefficient = 0.62; 95% CI: 0.58-0.65; p < .0001 and Kendall's τ statistic = 0.53; 95% CI: 0.49-0.56; p < .0001). Conclusions: The results of this study indicate a significant correlation between MFS and OS. It may justify the usefulness of MFS as surrogate for OS in nmCRPC.

Identification of SPP1 as an Extracellular Matrix Signature for Metastatic Castration-Resistant Prostate Cancer

Resistance to androgen deprivation therapy (ADT) is the main challenge for advanced fatal prostate cancer (PCa), which can gradually develop into metastatic castration-resistant prostate cancer (mCRPC). However, the pathologic mechanisms of mCRPC are still far from clear. Given the high incidence and mortality related to mCRPC, understanding the causes and pathogenesis of this condition as well as identifying potential biomarkers are of great importance. In the research reported here, we integrated several gene expression profiles from hormone sensitive prostate cancer (HSPC) and mCRPC datasets to identify differentially expressed genes (DEGs), key biological pathways, and cellular components. We found that extracellular matrix (ECM) genes were significantly enriched, and further filtered them using Pearson correlation analysis and stepwise regression to find ECM signatures to differentiate between the HSPC and mCRPC phenotypes. Six ECM signatures were input into K-nearest neighbor, logistic regression, naive Bayes, and random forest classifiers models. Random forest algorithm with the six-gene prognostic signatures showed best performance, which had high sensitivity and specificity for HSPC and mCRPC classification and further the six ECM signatures were validated in organoid models. Among the six ECM genes, SPP1 was identified as the key hub signature for PCa metastasis and drug resistance development; we found that both protein and mRNA expression levels of SPP1 were remarkably up-regulated in mCRPC compared with HSPC in organoid models and could regulate the androgen receptor signaling pathway. Therefore, SPP1 is a potential novel biomarker and therapeutic target for mCRPC. Further understanding of the role of SPP1 in mCRPC development may help to explore effectively therapeutic approaches for the prevention and intervention of drug resistance and metastasis.

Symptoms and Impacts in Metastatic Castration-Resistant Prostate Cancer: Qualitative Findings from Patient and Physician Interviews

BACKGROUND

There is little information available on health-related quality of life in patients with chemotherapy-naïve metastatic castration-resistant prostate cancer. This study aimed to develop a conceptual model that describes patients' experiences of living with this condition.

METHODS

This was a cross-sectional, non-interventional qualitative research study. Sixty-minute semi-structured interviews were conducted with physicians experienced in treating metastatic castration-resistant prostate cancer and with chemotherapy-naïve patients with metastatic castration-resistant prostate cancer. Interviews were audio-recorded and transcripts were analysed to identify the key symptoms and impacts on quality of life. Results were used to expand a previously published conceptual model for non-metastatic castration-resistant prostate cancer.

RESULTS

Three physicians and 19 patients with metastatic castration-resistant prostate cancer were interviewed. Physicians identified several symptoms frequently mentioned by their patients: fatigue, bone pain, anxiety, stress, depression and interference with daily activities. The most salient symptoms emerging from the patient interviews were urinary frequency and urgency, fatigue, pain/stiffness and sexual dysfunction. The most salient impacts were interference with daily activities, frustration, anxiety and sleep problems. Compared with non-metastatic castration-resistant prostate cancer, some symptoms and impacts in metastatic castration-resistant prostate cancer were more common and rated as more disturbing (e.g. fatigue, pain, urinary frequency, interference with daily activities and frustration). New concepts that were added to the non-metastatic castration-resistant prostate cancer model, to more accurately reflect the experiences of patients with metastatic disease, were enlarged breasts, muscle loss/deconditioning, inability to focus/mental slowing, body image perception, interference with work and lack of ambition/motivation.

CONCLUSIONS

Chemotherapy-naïve patients with metastatic castration-resistant prostate cancer experience a substantial burden from their condition. Furthermore, as castration-resistant prostate cancer progresses from the non-metastatic stage to the early metastatic (pre-chemotherapy) stage, certain symptoms become more common and disturb patients' lives to a greater extent. The resulting conceptual model for metastatic castration-resistant prostate cancer highlights areas that are not adequately assessed with current patient-reported outcome instruments.

Patient-reported outcomes following enzalutamide or placebo in men with non-metastatic, castration-resistant prostate cancer (PROSPER): a multicentre, randomised, double-blind, phase 3 trial

BACKGROUND

In the PROSPER trial, enzalutamide significantly improved metastasis-free survival in patients with non-metastatic, castration-resistant prostate cancer. Here, we report the results of patient-reported outcomes of this study.

METHODS

In the randomised, double-blind, placebo-controlled, phase 3 PROSPER trial, done at 254 study sites worldwide, patients aged 18 years or older with non-metastatic, castration-resistant prostate cancer and a prostate-specific antigen doubling time of up to 10 months were randomly assigned (2:1) via an interactive voice web recognition system to receive oral enzalutamide (160 mg per day) or placebo. Randomisation was stratified by prostate-specific antigen doubling time and baseline use of a bone-targeting agent. The primary endpoint was metastasis-free survival, reported elsewhere. Secondary efficacy endpoints, reported here, were pain progression (assessed by the Brief Pain Inventory Short Form [BPI-SF] questionnaire) and health-related quality of life (assessed with the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire [EORTC QLQ-PR25], the EuroQoL 5-Dimensions 5-Levels health questionnaire visual analogue scale [EQ-5D-FL, EQ-VAS], and the Functional Assessment of Cancer Therapy-Prostate [FACT-P] questionnaires). Patients completed questionnaires at baseline, week 17, and every 16 weeks thereafter until treatment discontinuation. We used predefined questionnaire thresholds to identify clinically meaningful changes. Enrolment for PROSPER is complete and follow-up continues. This trial is registered with ClinicalTrials.gov, number NCT02003924.

FINDINGS

Between Nov 26, 2013, and June 28, 2017, 1401 patients were enrolled and randomly assigned to receive enzalutamide (n=933) or placebo (n=468). Median follow-up was 18·5 months (IQR 10·7-29·2) in the enzalutamide group and 15·1 months (7·4-25·9) in the placebo group. Patient-reported outcome scores at baseline were similar between groups. Changes in least squares mean from baseline to week 97 favoured enzalutamide versus placebo for FACT-P social and family wellbeing (0·30 [95% CI -0·25 to 0·85] vs -0·64 [-1·51 to 0·24]; difference 0·94 [95% CI 0·02 to 1·85]; p=0·045) and disfavoured enzalutamide versus placebo for EORTC QLQ-PR25 hormonal treatment-related symptoms (1·55 [0·26 to 2·83) vs -1·83 [-3·86 to 0·20]; difference 3·38 [1·24 to 5·51]; p=0·0020); neither of these changes were clinically meaningful. No significant differences were observed between treatments for changes from baseline to week 97 in any other patient-reported outcome score. Time to clinically meaningful pain progression as assessed by BPI-SF pain severity was longer with enzalutamide than with placebo (median 36·83 months, [95% CI 34·69 to not reached [NR] vs NR; hazard ratio [HR] 0·75 [95% CI 0·57 to 0·97]; p=0·028); there was no significant difference for BPI-SF item 3 or pain interference. Time to clinically meaningful symptom worsening was longer with enzalutamide than with placebo for EORTC QLQ-PR25 urinary symptoms (median 36·86 months [95% CI 33·35 to NR] vs 25·86 [18·53 to 29·47]; HR 0·58 [95% CI 0·46 to 0·72]; p<0·0001) and bowel symptoms (33·15 [29·50 to NR] vs 25·89 [18·43 to 29·67]; 0·72 [0·59 to 0·89]; p=0·0018), and clinically meaningful health-related quality of life as assessed by FACT-P total score (22·11 [18·63 to 25·86] vs 18·43 [14·85-19·35]; 0·83 [0·69 to 0·99]; p=0·037), emotional wellbeing (36·73 [33·12 to 38·21] vs 29·47 [22·18 to 33·15]; 0·69 [0·55 to 0·86]; p=0·0008), and prostate cancer subscale (18·43 [14·85 to 18·66] vs 14·69 [11·07 to 16·20]; 0·79 [0·67 to 0·93]; p=0·0042), although there was no significant difference for other FACT-P scores. Time to clinically meaningful deterioration in EORTC QLQ-PR25 hormonal treatment-related symptoms was shorter with enzalutamide than with placebo (median 33·15 months [95% CI 29·60 to NR] vs 36·83 [29·47 to NR]; HR 1·29 [95% CI 1·02 to 1·63]; p=0·035). Time to deterioration of EQ-VAS was significantly longer for enzalutamide than for placebo (median 22·11 months [95% CI 18·46 to 25·66] vs 14·75 [11·07 to 18·17]; HR 0·75 [95% CI 0·63 to 0·90]; p=0·0013).

INTERPRETATION

Patients with non-metastatic, castration-resistant prostate cancer receiving enzalutamide had longer metastasis-free survival than did those who received placebo, while maintaining low pain levels and prostate cancer symptom burden and high health-related quality of life. Enzalutamide showed a clinical benefit by delaying pain progression, symptom worsening, and decrease in functional status, compared with placebo. These findings suggest that enzalutamide is a treatment option that should be discussed with patients presenting with high-risk, non- metastatic, castration-resistant prostate cancer.

FUNDING

Astellas Pharma Inc, Medivation LLC (a Pfizer Company).

Impact of age, comorbidity, and PSA doubling time on long-term competing risks for mortality among men with non-metastatic castration-resistant prostate cancer

BACKGROUND

Understanding competing risks for mortality is critical in determining prognosis among men with non-metastatic castration-resistant prostate cancer (nmCRPC), a disease state that often affects older men and has substantial heterogeneity in risk of cancer mortality. We sought to determine the impact of age, comorbidity, and PSA doubling time (PSADT) on competing risks for mortality in men with nmCRPC.

METHODS

We conducted a retrospective analysis of 1238 patients diagnosed with nmCRPC in 2000-2015 in the SEARCH database. Multivariable Cox proportional hazards and competing risks regression were used to determine the hazards of overall, prostate cancer-specific (PCSM), and other-cause mortality (OCM) across age, Charlson comorbidity index (CCI), and PSADT subgroups.

RESULTS

Men with nmCRPC were elderly (median age 77) and had substantial comorbidity burdens (CCI > 1 n = 701, 57%). Multivariable Cox analysis showed higher CCI was associated with higher hazard of OCM, while slower PSADT was associated with lower hazard of PCSM across all age subgroups. Among those with CCI ≥ 3 (vs. CCI0), the hazard ratio of OCM was 2.7 (95% CI 1.1-6.3), 2.0 (95% CI 1.1-3.6), and 2.5 (95% CI 1.5-4.0) for those aged <70, 70-79, and ≥80, respectively. Among those with PSADT ≥ 9 months (vs. < 9 months), the hazard ratios for PCSM were 0.5 (95% CI 0.3-0.9), 0.6 (95% CI 0.4-0.9), and 0.6 (95% CI 0.4-0.9) for those aged <70, 70-79, and ≥80. Competing risks curves revealed PCSM was the predominant cause of death for those with PSADT < 9 months across all age and comorbidity groups. PCSM and OCM were relatively equal competitors for mortality among those with PSADT≥9 months except those aged > 80 with CCI ≥ 3, in whom OCM was the predominant cause of death.

CONCLUSIONS

Among men with nmCRPC, age, comorbidity, and PSADT are associated with risk and cause of death and may assist clinicians in counseling patients regarding cancer prognosis.

Pharmacokinetic/pharmacodynamic drug evaluation of enzalutamide for treating prostate cancer

INTRODUCTION

Enzalutamide is the first approved second-generation androgen receptor (AR) antagonist in the treatment of metastatic castration-resistant prostate cancer (mCRPC) with or without docetaxel-based chemotherapy. Over the past 5 years, a number of attempts were made to determine the efficacy of enzalutamide in the different clinical settings. Areas covered: A literature search was performed at the PubMed, Embase, and Web of Science database to collect the most relevant and impactful studies, including basic science investigations, clinical trials, and reviews. This article focuses on the pharmacology, efficacy, tolerability, and future perspective of enzalutamide. Expert opinion: The treatment paradigm of CRPC has been dramatically challenged of late. Enzalutamide are in wide use because of its favorable efficacy and safety, but primary or acquired resistance to the drug will eventually develop. Further studies are thus necessary to identify appropriate patients who can achieve apparent benefits from enzalutamide alone or in combination with other drugs.

Dual targeting of androgen receptor and mTORC1 by salinomycin in prostate cancer

Androgen receptor (AR) and PI3K/AKT/mTORC1 are major survival signals that drive prostate cancer to a lethal disease. Reciprocal activation of these oncogenic pathways from negative cross talks contributes to low/limited success of pathway-selective inhibitors in curbing prostate cancer progression. We report that the antibiotic salinomycin, a cancer stem cell blocker, is a dual-acting AR and mTORC1 inhibitor, inhibiting PTEN-deficient castration-sensitive and castration-resistant prostate cancer in culture and xenograft tumors. AR expression, its transcriptional activity, and androgen biosynthesis regulating enzymes CYP17A1, HSD3β1 were reduced by sub-micro molar salinomycin. Estrogen receptor-α expression was unchanged. Loss of phosphorylated AR at serine-81, which is an index for nuclear AR activity, preceded total AR reduction. Rapamycin enhanced the AR protein level without altering phosphoAR-Ser81 and CYP17A1. Inactivation of mTORC1, evident from reduced phosphorylation of mTOR and downstream effectors, as well as AMPK activation led to robust autophagy induction. Apoptosis increased modestly, albeit significantly, by sub-micro molar salinomycin. Enhanced stimulatory TSC2 phosphorylation at Ser-1387 by AMPK, and reduced inhibitory TSC2 phosphorylation at Ser-939/Thr-1462 catalyzed by AKT augmented TSC2/TSC1 activity, which led to mTORC1 inhibition. AMPK-mediated raptor phosphorylation further reduced mTOR's kinase function and mTORC1 activity. Our novel finding on dual inhibition of AR and mTORC1 suggests that salinomycin is potentially active as monotherapy against advanced prostate cancer.

Symptoms and Impacts in Non-Metastatic Castration-Resistant Prostate Cancer: Qualitative Study Findings

OBJECTIVES

We developed a conceptual model to define key concepts associated with patients' experiences with the signs, symptoms, and impacts of non-metastatic castration-resistant prostate cancer (M0-CRPC).

METHODS

A targeted review of peer-reviewed literature, and other publicly available information, identified and categorized symptoms and impacts related to early-stage prostate cancer. Semi-structured interviews with five clinical experts helped determine the most relevant and important concepts for patients with M0-CRPC. Qualitative interviews with 17 patients with M0-CRPC identified the most frequently experienced symptoms and impacts, and their degree of interference with patients' lives. The findings from these three lines of evidence were summarized in a conceptual model.

RESULTS

Literature searches identified mainly urinary, intestinal, and sexual symptoms. Experts noted the symptoms most frequently mentioned by patients include erectile dysfunction, loss of sexual desire or interest, incontinence/leaking, urgency, and hot flashes. Patient interviews confirmed the high frequency of erectile dysfunction, loss of libido, urinary urgency, and incontinence. The most frequently mentioned impacts expressed by patients were the need to monitor/plan for urinary frequency, interference with/restriction of daily activities, and frustration or anxiety over diagnosis, symptoms, or treatment. Symptoms and impacts most frequently experienced by patients were typically not those with the greatest effects on their lives; rather, those with the greatest consequences were related to treatment.

CONCLUSIONS

The leading concerns associated with M0-CRPC were related to voiding and sexual dysfunction. The most relevant symptoms and impacts expressed by patients may be a consequence of therapy rather than of the disease.

Treatment of metastatic castration-resistant prostate cancer (mCRPC) with enzalutamide

Prostate cancer is initially responsive to androgen deprivation therapy, but most patients eventually develop castration-resistant disease. Enzalutamide is an androgen receptor (AR) inhibitor that targets several steps in the AR signaling pathway and has shown significant efficacy in the treatment of metastatic castration-resistant prostate cancer in patients with or without prior chemotherapy. To provide optimal treatment, it is important to understand the implications of enzalutamide use in the context of other therapies, as recent findings have suggested cross-resistance occurs between and within drug classes. Mutations and splice variants of AR also impact the course of prostate cancer. Future strategies involving enzalutamide should account for previous exposure to taxanes or antiandrogen therapies and the presence of AR variants that could affect efficacy.

Enzalutamide Versus Bicalutamide in Castration-Resistant Prostate Cancer: The STRIVE Trial

PURPOSE

Enzalutamide, a potent oral androgen receptor inhibitor, improves survival in men with metastatic castration-resistant prostate cancer (CRPC) before and after chemotherapy. Bicalutamide, a nonsteroidal antiandrogen, is widely used to treat men with nonmetastatic or metastatic CRPC. The efficacy and safety of these drugs were compared in this randomized, double-blind, phase II study of men with CRPC.

PATIENTS AND METHODS

A total of 396 men with nonmetastatic (n = 139) or metastatic (n = 257) CRPC were randomly assigned to enzalutamide 160 mg per day (n = 198) or bicalutamide 50 mg per day (n = 198). Androgen deprivation therapy was continued in both arms. The primary end point was progression-free survival (PFS).

RESULTS

Enzalutamide reduced the risk of progression or death by 76% compared with bicalutamide (hazard ratio [HR], 0.24; 95% CI, 0.18 to 0.32; P < .001). Median PFS was 19.4 months with enzalutamide versus 5.7 months with bicalutamide. Enzalutamide resulted in significant improvements in all key secondary end points: time to prostate-specific antigen progression (HR, 0.19; 95% CI, 0.14 to 0.26; P < .001); proportion of patients with a ≥ 50% prostate-specific antigen response (81% v 31%; P < .001); and radiographic PFS in metastatic patients (HR, 0.32; 95% CI, 0.21 to 0.50; P < .001). Beneficial effects with enzalutamide were observed in both nonmetastatic and metastatic subgroups. The observed adverse event profile was consistent with that from phase III enzalutamide trials.

CONCLUSION

Enzalutamide significantly reduced risk of prostate cancer progression or death compared with bicalutamide in patients with nonmetastatic or metastatic CRPC.

ODM-201: a new-generation androgen receptor inhibitor in castration-resistant prostate cancer

Androgen deprivation therapy is the standard of care for patients with advanced hormone-sensitive prostate cancer. Despite an initial response, most patients progress to castration-resistant prostate cancer (CRPC). The realization that CRPC remains driven by androgen receptor (AR) signaling has formed the basis for a new generation of agents targeting the AR axis. Two of these agents, abiraterone acetate and enzalutamide, have been shown to prolong overall survival in patients with CRPC. Several other AR inhibitors are currently in development for the treatment of CRPC. The present article reviews ODM-201, a new-generation AR inhibitor with a unique molecular structure, in the treatment of CRPC. The design of an ongoing Phase III trial (ARAMIS) of ODM-201 in men with non-metastatic CRPC is also discussed, at a disease stage for which there is currently no approved treatment.

Potential utility of cancer-specific biomarkers for assessing response to hormonal treatments in metastatic prostate cancer

Prostate cancer is the second leading cause of cancer death in men and there is an urgent clinical need to improve its detection and treatment. The introduction of prostate-specific antigen (PSA) as a biomarker for prostate cancer several decades ago represented an important step forward in our ability to diagnose this disease and offers the potential for earlier and more effective treatment. PSA measurements are now routinely conducted alongside digital rectal examination, with raised PSA levels leading to biopsy. PSA is also used to monitor disease and assess therapeutic response. However, there are some important limitations to its use, not least its lack of specificity for prostate cancer, and increased PSA screening may have resulted in overdiagnosis and overtreatment of early, low-risk prostate cancer. Therefore, there is a need for more specific and sensitive biomarkers for the diagnosis and monitoring of prostate cancer and treatment response; in particular, biomarkers of response to hormonal treatments in prostate cancer and predictive biomarkers to identify who is most likely to respond to these treatments. Here we review the current utilization of PSA and data on potentially more specific and sensitive biomarkers for the diagnosis and monitoring of prostate cancer: prostate cancer antigen 3 (PCA3) and the TMPRSS2-ERG fusion gene. A description of the design of an ongoing study of the 6-month extended release formulation of leuprorelin acetate (Eligard(®) 45 mg) will provide preliminary data on the potential utility of these new biomarkers for detecting therapeutic response after hormonal therapy.

Nonmetastatic castration-resistant prostate cancer

After the introduction of prostate cancer screening with the prostate-specific antigen (PSA) test, we have witnessed a dramatic stage migration. As a result, an increasing number of patients are diagnosed at earlier stages and receive local treatments including surgery or radiation. When these local treatments fail by the definition of increasing PSA levels, patients are usually treated with androgen-deprivation therapy. A fraction of these patients will finally reach a state of castration-resistant prostate cancer (CRPC) even without radiological evidence of metastasis, which is referred to as nonmetastatic CRPC (NM-CRPC). Most men with advanced or metastatic prostate cancer initially respond to various types of androgen ablation, but a considerable portion of them eventually progress to NM-CRPC. Among patients with NM-CPRC, about one-third will develop bone metastasis within 2 years. In these patients, PSA kinetics is the most powerful indicator of progression and is usually used to trigger further imaging studies and enrollment in clinical trials. Although CRPC remains largely driven by the androgen receptor, the benefit of second-line hormonal manipulations, including first-generation antiandrogens, adrenal synthesis inhibitors, and steroids, has not been investigated in men with NM-CRPC. To date, denosumab is the only agent that has been shown to delay the onset of bone metastasis. However, overall survival did not differ. In treating NM-CRPC patients, physicians should recognize the heterogeneity of the disease and acknowledge that the recently approved second-line treatments have been studied only in advanced stages of the disease.

Progress in the treatment of advanced prostate cancer

The androgen receptor (AR) is the most significant target for patients with metastatic castration-resistant prostate cancer (mCRPC). There is now irrefutable evidence that the AR axis is functional in most patients throughout the history of prostate cancer, is crucial from diagnosis to death, even in patients who have received hormonal manipulation, and represents a relevant therapeutic target in all phases of the disease. The potential mechanisms of tumor escape after castration are multifold, with each mechanism today representing a therapeutic opportunity. Phase III trials have been able to demonstrate improved overall survival (OS), improved quality of life, decreased skeletal-related events, and other important clinical benefits in young and elderly patients. After the initial positive results with docetaxel chemotherapy in improving OS, further research has resulted in five new treatments in the past few years. Immunotherapy with sipuleucel-T, cabazitaxel chemotherapy, the androgen biosynthesis inhibitor abiraterone acetate, the antiandrogen enzalutamide, and the radioisotope radium-223 have all been shown to improve OS in large-scale, well-conducted clinical trials. Proper understanding of mechanisms of resistance and of cross-resistance among these agents, sequencing, and combinations is now a priority.