Antitumour activity of enzalutamide (MDV3100) in patients with metastatic castration-resistant prostate cancer (CRPC) pre-treated with docetaxel and abiraterone

Prostate Cancer: A Review

Importance

Prostate cancer is the most common nonskin cancer in men in the US, with an estimated 299 010 new cases and 35 250 deaths in 2024. Prostate cancer is the second most common cancer in men worldwide, with 1 466 680 new cases and 396 792 deaths in 2022.

Observations

The most common type of prostate cancer is adenocarcinoma (≥99%), and the median age at diagnosis is 67 years. More than 50% of prostate cancer risk is attributable to genetic factors; older age and Black race (annual incidence rate, 173.0 cases per 100 000 Black men vs 97.1 cases per 100 000 White men) are also strong risk factors. Recent guidelines encourage shared decision-making for prostate-specific antigen (PSA) screening. At diagnosis, approximately 75% of patients have cancer localized to the prostate, which is associated with a 5-year survival rate of nearly 100%. Based on risk stratification that incorporates life expectancy, tumor grade (Gleason score), tumor size, and PSA level, one-third of patients with localized prostate cancer are appropriate for active surveillance with serial PSA measurements, prostate biopsies, or magnetic resonance imaging, and initiation of treatment if the Gleason score or tumor stage increases. For patients with higher-risk disease, radiation therapy or radical prostatectomy are reasonable options; treatment decision-making should include consideration of adverse events and comorbidities. Despite definitive therapy, 2% to 56% of men with localized disease develop distant metastases, depending on tumor risk factors. At presentation, approximately 14% of patients have metastases to regional lymph nodes. An additional 10% of men have distant metastases that are associated with a 5-year survival rate of 37%. Treatment of metastatic prostate cancer primarily relies on androgen deprivation therapy, most commonly through medical castration with gonadotropin-releasing hormone agonists. For patients with newly diagnosed metastatic prostate cancer, the addition of androgen receptor pathway inhibitors (eg, darolutamide, abiraterone) improves survival. Use of abiraterone improved the median overall survival from 36.5 months to 53.3 months (hazard ratio, 0.66 [95% CI, 0.56-0.78]) compared with medical castration alone. Chemotherapy (docetaxel) may be considered, especially for patients with more extensive disease.

Conclusions and Relevance

Approximately 1.5 million new cases of prostate cancer are diagnosed annually worldwide. Approximately 75% of patients present with cancer localized to the prostate, which is associated with a 5-year survival rate of nearly 100%. Management includes active surveillance, prostatectomy, or radiation therapy, depending on risk of progression. Approximately 10% of patients present with metastatic prostate cancer, which has a 5-year survival rate of 37%. First-line therapies for metastatic prostate cancer include androgen deprivation and novel androgen receptor pathway inhibitors, and chemotherapy for appropriate patients.

Unveiling hormone-stimulated gene mechanisms in prostate cancer: A prognostic model, immune infiltration analysis, and drug sensitivity study

Hormones promote the progression of prostate cancer (PRCA) through the activation of a complex regulatory network. Inhibition of hormones or modulation of specific network nodes alone is insufficient to suppress the entire oncogenic network. Therefore, it is imperative to elucidate the mechanisms underlying the occurrence and development of PRCA in order to identify reliable diagnostic markers and therapeutic targets. To this end, we used publicly available data to analyze the potential mechanisms of hormone-stimulated genes in PRCA, construct a prognostic model, and assess immune infiltration and drug sensitivity. The single-cell RNA-sequencing data of PRCA were subjected to dimensionality reduction clustering and annotation, and the cells were categorized into two groups based on hormone stimulus-related scores. The differentially expressed genes between the two groups were screened and incorporated into the least absolute shrinkage and selection operator machine learning algorithm, and a prognostic model comprising six genes (ZNF862, YIF1A, USP22, TAF7, SRSF3, and SPARC) was constructed. The robustness of the model was validation through multiple methods. Immune infiltration scores in the two risk groups were calculated using three different algorithms. In addition, the relationship between the model genes and immune cell infiltration, and that between risk score and immune cell infiltration were analyzed. Drug sensitivity analysis was performed for the model genes and risk score using public databases to identify potential candidate drugs. Our findings provide novel insights into the mechanisms of hormone-stimulated genes in PRCA progression, prognosis, and drug screening.

IU1 and enzalutamide combination yields synergistic effects on castration-resistant prostate cancer

BACKGROUND

Androgen deprivation therapy (ADT) is one of the main treatment modalities for prostate cancer (PCa); however, almost all patients treated with ADT eventually progress into castration-resistant PCa (CRPC). Although second-generation androgen receptor (AR) antagonists, such as enzalutamide, have been approved for CRPC treatment, AR signaling in CRPC cells is reactivated through multiple mechanisms, resulting in resistance to treatment and tumor progression with a very poor prognosis. The present study aimed to explore the anticancer effect of a treatment combining AR antagonist enzalutamide with AR degrader IU1 on PCa cells.

METHODS

The joint effects of enzalutamide and IU1 on PCa cell proliferation and apoptosis and associated cell signaling were evaluated in vitro. Mechanistically, the ubiquitination level and half-life of AR were examined under the combination treatment. The binding of IU1 and enzalutamide to AR was further verified using cellular thermal shift analysis and isothermal dose-response curve fingerprinting.

RESULTS

The combination of IU1 and three AR antagonists showed synergistic effects in different prostate cell lines. IU1 and enzalutamide synergistically promoted the degradation of AR and AR-V7 proteins, as well as suppressed the expression levels of AR and AR-V7 downstream target genes at the transcriptional and protein levels. The combination also synergistically blocked the PCa cell cycle and promoted apoptosis in PCa cell lines. Mechanistically, the combination promoted increased levels of AR ubiquitination. In CRPC cell lines and in the presence of increased androgen concentrations, enzalutamide was still able to bind AR competitively with androgens, reducing the stability of AR and thus promoting the degradation effect of IU1 on AR, synergistically producing an inhibitory effect on PCa cells.

CONCLUSION

Taken together, our findings suggest that the combination of AR degrader and enzalutamide potentially represents a new therapeutic strategy for CRPC.

Establishing a Proteomics-Based Signature of AKR1C3-Related Genes for Predicting the Prognosis of Prostate Cancer

Aldo-keto reductase family 1 member C3 (AKR1C3) plays an important role in prostate cancer (PCa) progression, particularly in castration-resistant prostate cancer (CRPC). It is necessary to establish a genetic signature associated with AKR1C3 that can be used to predict the prognosis of PCa patients and provide important information for clinical treatment decisions. AKR1C3-related genes were identified via label-free quantitative proteomics of the AKR1C3-overexpressing LNCaP cell line. A risk model was constructed through the analysis of clinical data, PPI, and Cox-selected risk genes. Cox regression analysis, Kaplan-Meier (K-M) curves, and receiver operating characteristic (ROC) curves were used to verify the accuracy of the model, and two external datasets were used to verify the reliability of the results. Subsequently, the tumor microenvironment and drug sensitivity were explored. Moreover, the roles of AKR1C3 in the progression of PCa were verified in LNCaP cells. MTT, colony formation, and EdU assays were conducted to explore cell proliferation and drug sensitivity to enzalutamide. Migration and invasion abilities were measured using wound-healing and transwell assays, and qPCR was used to assess the expression levels of AR target genes and EMT genes. CDC20, SRSF3, UQCRH, INCENP, TIMM10, TIMM13, POLR2L, and NDUFAB1 were identified as AKR1C3-associated risk genes. These risk genes, established using the prognostic model, can effectively predict the recurrence status, immune microenvironment, and drug sensitivity of PCa. Tumor-infiltrating lymphocytes and several immune checkpoints that promote cancer progression were higher in high-risk groups. Furthermore, there was a close correlation between the sensitivity of PCa patients to bicalutamide and docetaxel and the expression levels of the eight risk genes. Moreover, through in vitro experiments, Western blotting confirmed that AKR1C3 enhanced SRSF3, CDC20, and INCENP expression. We found that PCa cells with a high expression of AKR1C3 have high proliferation ability and high migration ability and were insensitive to enzalutamide. AKR1C3-associated genes had a significant role in the process of PCa, immune responses, and drug sensitivity and offer the potential for a novel model for prognostic prediction in PCa.

Taxanes Versus Androgen Receptor Therapy as Second-Line Treatment for Castrate-Resistant Metastatic Prostate Cancer After First-Line Androgen Receptor Therapy

BACKGROUND

The optimal therapeutic sequence for metastatic castrate-resistance prostate cancer (mCRPC) is still debated. This study aimed to compare activity of taxanes (TAX) versus that of androgen-receptor therapy (ART) in men with mCRPC treated with first-line ART.

PATIENTS AND METHODS

This retrospective study included all consecutive chemo-naive mCRPC patients who have received first-line ART treatment. Progression-free survival (PFS) and overall survival (OS) were compared between patients treated with second-line ART or TAX.

RESULTS

Overall, 175 patients treated with first-line enzalutamide (ENZA, n = 75) or abiraterone (ABI, n = 100) were evaluated. Among them, 69 (39%) and 30 (17%) patients received second-line TAX and ART, respectively, while 76 (43%) patients did not receive further treatment. From the start of first-line therapy, the median PFS and OS were 13 months (95% CI: 11-15) and 34 months (95% CI: 29-39), respectively, without any significant difference between ENZA and ABI. From the start of second-line therapy, the median PFS and OS were 6 months (95% CI: 5-7) and 18 months (95% CI: 14-21), respectively. Compared with ART, docetaxel was associated with significantly higher prostate-specific antigen (PSA, ≥ 50%) (29% vs. 0%, P < .001) and radiological responses (21% vs. 0%, P < .001). PFS was longer in TAX than in ART (6.7 months vs. 4 months, HR: 0.63, 95% CI: 0.41-0.96, P = .034), but there was no significant difference in OS (19 months vs. 12 months, P = .1). After propensity score adjustment, PFS (P = .2) and OS (P = .1) were similar between second-line TAX and ART.

CONCLUSION

In the second-line setting, TAX provides higher PSA and radiological responses than does ART for mCRPC patients who received first-line ART, but the PFS and OS are similar. This study provides new elements to help deciding the best treatment sequence.

Lutetium Lu 177 vipivotide tetraxetan for metastatic castration-resistant prostate cancer

INTRODUCTION

¹⁷⁷Lu-vipivotide tetraxetan is a radiopharmaceutical that selectively targets prostate-specific membrane antigen (PSMA) and delivers beta-radiations to kill prostate cancer cells.

AREAS COVERED

Extensive experience outside the United States as well as randomized phase II and phase III data demonstrate that ¹⁷⁷Lu-vipivotide tetraxetan is a safe, generally well tolerated, and effective therapy for men with mCRPC. ¹⁷⁷Lu-vipivotide tetraxetan was approved by the FDA in March 2022 for the treatment of PSMA-positive metastatic castration-resistant prostate cancer (mCRPC) after androgen receptor pathway inhibition and taxane-based chemotherapy based on the results of the VISION trial.

EXPERT OPINION

This review discusses the development and studies leading to the approval of ¹⁷⁷Lu-vipivotide tetraxetan. In all, ¹⁷⁷Lu-vipivotide tetraxetan is an exciting new tool in the arsenal for men with mCRPC after novel androgen pathway inhibitors and at least one taxane chemotherapy. Optimal selection of patients, sequencing of ¹⁷⁷Lu-vipivotide tetraxetan with the other agents available to treat mCRPC, and the use of dosimetry are current areas of interest with great potential and opportunities for further individual patient optimization using the tools of theranostics.

An economic evaluation of cabazitaxel versus a second androgen receptor-targeted agent (ARTA) for patients with metastatic castration-resistant prostate cancer previously treated with docetaxel and an ARTA: the United States payer perspective

Background

Cabazitaxel significantly improves clinical outcomes compared with a second androgen receptor-targeted agent (ARTA) in patients with metastatic castration-resistant prostate cancer (mCRPC) previously treated with docetaxel and an ARTA (abiraterone or enzalutamide), as demonstrated in the CARD trial (NCT02485691). We aimed to estimate healthcare costs avoided with the use of cabazitaxel as a third-line (3 L) treatment versus a second ARTA from a US payer perspective.

Methods

Model inputs were based on the CARD trial, published sources, and estimates of typical clinical care patterns by genitourinary oncologists (n = 3). Assessed time points were 6, 12, 18, and 24 months. Outcomes included progression-free survival (PFS), radiographic PFS (rPFS), and overall survival (OS); hospitalization and intensive care unit (ICU) days; and costs (reported in 2020 US dollar [USD] and converted into Euro) to manage symptomatic skeletal events (SSEs), adverse events (AEs), and end-of-life care.

Results

At 18 months, in a cohort of 100 patients, the use of cabazitaxel was estimated to result in 9 more patients achieving rPFS, 2 more patients achieving PFS, and 17 more survivors versus a second ARTA. The costs of SSEs, AEs, and end-of-life care were $498,909 (€424,073), $276,198 (€234,768), and $808,785 (€687,468), respectively, for cabazitaxel and $627,569 (€533,434), $251,124 (€213,455), and $1,028,294 (€874,050), respectively, for a second ARTA. Cabazitaxel was estimated to be associated with a 21% reduction in both SSE management and end-of-life care costs. Hospitalization cost was $1,442,870 (€1,226,440) for cabazitaxel and $1,728,394 (€1,469,135) for a second ARTA, representing an estimated 17% reduction in these costs. Cabazitaxel, as compared with a second ARTA, was associated with 58 fewer hospitalization days and 2 fewer ICU days and was estimated to avoid $323,095 (€274,630, 17%) in total costs, driven by SSEs management and end-of-life care.

Conclusion

The use of cabazitaxel as a 3 L treatment after docetaxel and an ARTA in patients with mCRPC is estimated to result in clinical benefits (longer rPFS, PFS, and OS) and lower healthcare resource utilization (fewer hospitalization and ICU days), compared with a second ARTA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12913-022-08274-x.

Non-drug efflux function of ABCC5 promotes enzalutamide resistance in castration-resistant prostate cancer via upregulation of P65/AR-V7

Drug resistance is responsible for castration-resistant prostate cancer (CRPC)-associated mortality. While ATP binding cassette subfamily C member 5 (ABCC5) has been reported to regulate multiple drug resistance, its drug-efflux function may not be the main reason underlying resistance to enzalutamide, an androgen receptor inhibitor. Here, we aimed to determine whether the non-drug efflux function of ABCC5 affects enzalutamide resistance. The ABCC5 expression data in patients with prostate cancer (PCa) were retrieved from The Cancer Genome Atlas and Gene Expression Omnibus, and their correlation with disease prognosis was analyzed. Immunohistochemical staining was performed on a cohort of 80 patient samples. Proliferation of enzalutamide-resistant 22RV1 and C4-2B cells was investigated using CCK-8, EdU, and colony formation assays. The effect of ABCC5 silencing on enzalutamide resensitization was evaluated in vitro and in vivo. Functional assays indicated that ABCC5 depletion resensitized enzalutamide-resistant cells to inhibit cell growth and impeded xenograft tumor proliferation. Mechanistically, luciferase and ChIP assays confirmed that P65 regulated AR expression and activity by binding to its promoter, while ABCC5-mediated resistance effected by AR-V7 (one of the widely studied AR splicing variants that meditate AR antagonist resistance) upregulation could be reversed by P65 knockdown. Furthermore, activation of the NF-κB pathway reversed the effects of ABCC5 knockdown by extra AR-V7 expression. Thus, ABCC5 might be a novel target for enzalutamide-resistant CRPC treatment.

Clinical Applications of Liquid Biopsy in Prostate Cancer: From Screening to Predictive Biomarker

Prostate cancer (PC) remains the most common malignancy and the second most common cause of cancer death in men. As a result of highly variable biological behavior and development of resistance to available agents under therapeutic pressure, optimal management is often unclear. Traditional surgical biopsies, even when augmented by genomic studies, may fail to provide adequate guidance for clinical decisions as these can only provide a snapshot of a dynamic process. Additionally, surgical biopsies are cumbersome to perform repeatedly and often involve risk. Liquid biopsies (LB) are defined as the analysis of either corpuscular (circulating tumor cells, extracellular vesicles) or molecular (circulating DNA or RNA) tumor-derived material. LB could more precisely identify clinically relevant alterations that characterize the metastatic potential of tumors, predict response to specific treatments or actively monitor for the emergence of resistance. These tests can potentially be repeated as often as deemed necessary and can detect real-time response to treatment with minimal inconvenience to the patient. In the current review, we consider common clinical scenarios to describe available LB assays in PC as a platform to explore existing evidence for their use in guiding decision making and to discuss current limitations to their adoption in the clinic.

Comparative Effectiveness of Abiraterone and Enzalutamide in Patients With Metastatic Castration-Resistant Prostate Cancer in Taiwan

Background

Abiraterone and enzalutamide are widely used as first-line treatment for metastatic castration-resistant prostate cancer (mCRPC); however, their efficacy in mCRPC has been inconsistently demonstrated in other outcome studies from real-world databases. The aim of our study was to assess the comparative effectiveness of abiraterone and enzalutamide in patients with mCRPC using real-world data from Taiwan.

Methods

This retrospective cohort population-based study included patients identified in the Taiwan National Health Insurance Research Database who had been diagnosed with mCRPC and who had taken abiraterone or enzalutamide between December 2014 and August 2017. The study’s outcome evaluated the differences in overall survival (OS) and time to treatment failure (TTF) between abiraterone and enzalutamide over a 15-month follow-up period. The patients were followed from the index date to when the outcome occurred, to December 31, 2018, or to the patients’ withdrawal from the National Health Insurance program. The estimated relative treatment effects of abiraterone and enzalutamide on OS and TTF were adjusted by the inverse probability of treatment weighting (IPTW) using the Kaplan–Meier method and a Cox proportional hazards model.

Results

The abiraterone and enzalutamide groups consisted of 1,046 and 118 patients, respectively. After IPTW adjustment, 1,164 patients in the abiraterone group and 1,158 in the enzalutamide group underwent an outcome evaluation. Enzalutamide showed a similar OS rate to that of abiraterone (57.58% vs. 49.51%, p = 0.095 by log-rank test). Enzalutamide significantly reduced the risk of death for mCRPC when compared with abiraterone [adjusted hazard ratio (aHR), 0.828; 95% CI 0.731–0.938]. However, similar results were not observed in the TTF outcomes (63.84% vs. 67.79%, p = 0.2651 by log-rank test; aHR, 0.902; 95% CI 0.812–1.002).

Conclusion

In conclusion, enzalutamide was associated with better OS for mCRPC than abiraterone in the Taiwan population. Our study showed that there was no statistically significant difference in TTF between enzalutamide and abiraterone. Studies with longer surveillance of enzalutamide and abiraterone using real-world databases are needed.

Abiraterone, Orteronel, Enzalutamide and Docetaxel: Sequential or Combined Therapy?

Objective: To summarize the current therapeutic status using chemotherapeutic agent docetaxel and endocrine therapeutic agents (ARAT, abiraterone, orteronel or enzalutamide) for the treatment of metastatic castration-resistant prostate cancer (mCRPC), including sequential therapy and combined therapy, to promote the consensus on the optimal regimen for achieving superior treatment efficacy.

Methods: Through literature search in PubMed, articles with the following relevant keywords were collected and anlyzed: CRPC, abiraterone, orteronel and enzalutamide, median survival, overall survival, prostate specific antigen (PSA), PSA response rate and median radiologic progression-free survival.

Results: Fifty-eight articles were obtained and analyzed in this review. These articles included androgen axis-targeting agents after docetaxel, docetaxel after androgen axis-targeting agents, Triple sequential and combination therapy, covering four current drugs for mCRPC treatment: docetaxel, abiraterone, orteronel, and enzalutamide. It was found that there may be some cross-resistance between androgen axis-targeting agents, which will reduce the efficacy of subsequent drug treatment. Although neither of the studies of using combination therapy showed serious drug toxicity, the efficacy of sequential therapy was not as good as expected. Most adverse reactions after treatment were reported to be level 1–2.

Conclusion: Based on the results of the current studies, abiraterone followed by enzalutamide treatment is the best sequential treatment for most docetaxel-naïve patients. This treatment achieves not only good OS, but also PFS and PSA response rates. In addition, for patients who have previously failed docetaxel treatment, enzalutamide is the best choice as the subsequent treatment.

[CARD study: relevance for the treatment of advanced prostate cancer]

BACKGROUND

 Various life-prolonging therapy options are available for the treatment of metastatic castration-resistant prostate cancer (mCRPC).

OBJECTIVE

 The optimal therapy sequence for mCRPC has been discussed for years. With the final results of the CARD study, important prospective data are available to enlighten the discussion about the therapy sequence.

MATERIAL AND METHOD

 CARD is a randomised phase IV trial in patients with mCRPC who were previously treated with docetaxel and an anti-androgen receptor (ARTA). The study showed significant efficacy benefits in favour of further treatment with cabazitaxel versus a second ARTA therapy. The study results are presented and discussed in the context of previous study data with regard to their importance for everyday clinical practice.

RESULTS

 The CARD study data confirm cabazitaxel as an effective therapy option for mCRPC patients previously treated with docetaxel and an ARTA. Cabazitaxel was safe to apply. The study results confirm the cross resistance between the two ARTAs Abiraterone and Enzalutamide.

CONCLUSION

In mCRPC patients eligible for chemotherapy, the therapy sequence should be chosen so that the patients also receive cabazitaxel. A direct therapy sequence with two ARTAs should be avoided or, at least, only considered if other substances are contraindicated.

Sequencing of Systemic Therapies in the Management of Advanced Prostate Cancer in India: a Delphi-Based Consensus

INTRODUCTION

With the availability of an increasing number of therapeutic options for advanced prostate cancer (APC), optimal sequencing and combination of therapies have emerged to be the areas of challenges. In the Indian context, there is a dearth of consensus recommendations to guide clinicians regarding optimal sequencing of therapy in APC management. A Delphi-based consensus regarding optimal therapy sequencing in APC management was developed by an expert panel of medical oncologists from across India.

METHODS

An expert scientific committee of 11 medical oncologists and an expert panel of 53 medical oncologists from India constituted the panel for the Delphi consensus. In the first phase, a questionnaire with 41 clinical statements was developed in several critical controversial areas in APC treatment. In the second phase, 29 clinical statements were reworked and sent to eight experts to obtain their opinions on best practices. The consensus ratings were based on a 9-point Likert scale. Based on the overall response, statements with a mean score of ≥ 7 with 1 outlier were considered as "consensus."

RESULTS

Degarelix was the preferred androgen deprivation therapy (ADT). While ADT plus docetaxel was the preferred option for metastatic castrate-sensitive/naïve prostate cancer patients with high-volume disease, ADT with abiraterone was the preferred choice for low-volume disease. Docetaxel was the preferred first-line treatment option in men who received ADT alone in the castrate-sensitive/naïve setting. For patients progressing on or after docetaxel for metastatic castrate-resistant prostate cancer (without prior abiraterone or enzalutamide), the experts reached a consensus on the use of enzalutamide as the preferred second-line treatment option. No consensus was reached for the third-line treatment options.

CONCLUSION

This article is intended to serve as a guide to help clinicians discuss with their patients as part of the shared and multidisciplinary decision-making for improved APC management in India.

The circRAB3IP Mediated by eIF4A3 and LEF1 Contributes to Enzalutamide Resistance in Prostate Cancer by Targeting miR-133a-3p/miR-133b/SGK1 Pathway

An increasing number of studies have shown that circRNAs are closely related to the carcinogenesis and development of prostate cancer (PCa). However, little is known about the effect of the biological functions of circRNAs on the enzalutamide resistance of PCa. Through bioinformatic analysis and experiments, we investigated the expression pattern of circRNAs in enzalutamide-resistant PCa cells. Quantitative real-time PCR was used to detect the expression of circRAB3IP, and plasmids that knock down or overexpress circRAB3IP were used to evaluate its effect on the enzalutamide sensitivity of PCa cells. Mechanistically, we explored the potential regulatory effects of eIF4A3 and LEF1 on the biogenesis of circRAB3IP. Our in vivo and in vitro data indicated that increased expression of circRAB3IP was found in enzalutamide-resistant PCa, and knockdown of circRAB3IP significantly enhanced enzalutamide sensitivity in PCa cells. However, upregulation of circRAB3IP resulted in the opposite effects. Further mechanistic research demonstrated that circRAB3IP could regulate the expression of serum and glucocorticoid-regulated kinase 1 (SGK1) by serving as a sponge that directly targets miR-133a-3p/miR-133b. Then, we showed that circRAB3IP partially exerted its biological functions via SGK1 signaling. Furthermore, we discovered that eIF4A3 and LEF1 might increase circRAB3IP expression in PCa.

Stereotactic body radiotherapy for oligoprogressive lesions in metastatic castration-resistant prostate cancer patients during abiraterone/enzalutamide treatment

BACKGROUND

Metastasis-directed therapy (MDT) utilizing stereotactic body radiotherapy (SBRT) for oligoprogressive lesions could provide a delay in next-line systemic treatment (NEST) change while undergoing androgen receptor-targeted agents (ARTA) treatment. We evaluated prognostic factors for prostate cancer-specific survival (PCSS) and progression-free survival (PFS) to characterize patients receiving treatment with ARTA who may benefit from MDT for oligoprogressive lesions. The impact of MDT on delaying NEST and the predictive factors for NEST-free survival (NEST-FS) were also assessed.

MATERIALS AND METHODS

The clinical data of 54 metastatic castration-resistant prostate cancer patients with 126 oligoprogressive lesions receiving abiraterone (1 g/day) or enzalutamide (160 mg/day) before or after systemic chemotherapy were analyzed. A median of three lesions (range: 1-5) were treated with MDT. The primary endpoints were PCSS and PFS. The secondary endpoints were time to switch to NEST and NEST-FS.

RESULTS

The median follow-up time was 19.1 months. Univariate analysis showed that the number of oligoprogressive lesions treated with SBRT and the time between the start of ARTA treatment and oligoprogression were significant prognostic factors for PCSS, and the timing of ARTA treatment (before or after chemotherapy) and the prostate-specific antigen (PSA) response after MDT were significant prognostic factors for PFS. Multivariate analysis showed that early MDT for oligoprogressive lesions delivered less than 6 months after the beginning of ARTA and higher PSA levels after MDT were significant predictors of worse PCSS and PFS. The median total duration of ARTA treatment was 13.8 months. The median time between the start of ARTA treatment and the start of MDT for oligoprogressive lesions was 5.2 months, and MDT extended the ARTA treatment by 8.6 months on average. Thirty-two (59.3%) patients continued ARTA treatment after MDT. ARTA treatment after chemotherapy, early oligoprogression requiring MDT, and lower radiation doses for MDT were independent predictors of NEST-FS in multivariate analysis.

CONCLUSIONS

MDT for oligoprogressive lesions is effective and may provide several benefits compared to switching from ARTA treatment to NEST. Patients with early progression while on ARTAs and inadequate PSA responses after MDT have a greater risk of rapid disease progression and poor survival, which necessitates intensified treatment.

Cross-resistance and drug sequence in prostate cancer

The treatment landscape of advanced prostate cancer has widely expanded over the past years with androgen receptor signaling inhibitors (ARSIs) and taxane chemotherapy moving to earlier disease stages in the treatment of prostate cancer. With the increasing use of ARSIs in earlier disease stages, cross-resistance between treatments has emerged, which is a dominant impediment in current clinical practice. To overcome cross-resistance in the treatment of prostate cancer, it is of paramount importance to decipher the mechanisms of cross-resistance between ARSIs and between ARSIs and chemotherapy. Here, molecular mechanisms of resistance to the available therapies including androgen receptor (AR) splice variants, AR overexpression, AR mutations and glucocorticoid receptor upregulation are described. Based on these underlying mechanisms, clinical data of cross-resistance between ARSIs and chemotherapy have been reported. Only recently these data have been confirmed in prospective randomized trials. From these studies, it has become clear that sequential ARSI treatment has no place in the treatment of advanced prostate cancer due to emerging drug resistance. In addition, based on prospective evidence, we argue that it is worth considering an early switch to cabazitaxel treatment in case of lack of benefit on docetaxel regimen after an ARSI treatment. Based on these new insights from randomized trials, several recommendations for treatment sequence are proposed.

Cross-Resistance to Abiraterone and Enzalutamide in Castration Resistance Prostate Cancer Cellular Models Is Mediated by AR Transcriptional Reactivation

Androgen deprivation therapy (ADT) and novel hormonal agents (NHAs) (Abiraterone and Enzalutamide) are the goal standard for metastatic prostate cancer (PCa) treatment. Although ADT is initially effective, a subsequent castration resistance status (CRPC) is commonly developed. The expression of androgen receptor (AR) alternative splicing isoforms (AR-V7 and AR-V9) has been associated to CRPC. However, resistance mechanisms to novel NHAs are not yet well understood. Androgen-dependent PCa cell lines were used to generate resistant models to ADT only or in combination with Abiraterone and/or Enzalutamide (concomitant models). Functional and genetic analyses were performed for each resistance model by real-time cell monitoring assays, flow cytometry and RT-qPCR. In androgen-dependent PCa cells, the administration of Abiraterone and/or Enzalutamide as first-line treatment involved a critical inhibition of AR activity associated with a significant cell growth inhibition. Genetic analyses on ADT-resistant PCa cell lines showed that the CRPC phenotype was accompanied by overexpression of AR full-length and AR target genes, but not necessarily AR-V7 and/or AR-V9 isoforms. These ADT resistant cell lines showed higher proliferation rates, migration and invasion abilities. Importantly, ADT resistance induced cross-resistance to Abiraterone and/or Enzalutamide. Similarly, concomitant models possessed an elevated expression of AR full-length and proliferation rates and acquired cross-resistance to its alternative NHA as second-line treatment.

NCCN Guidelines Insights: Prostate Cancer, Version 1.2021

The NCCN Guidelines for Prostate Cancer address staging and risk assessment after a prostate cancer diagnosis and include management options for localized, regional, and metastatic disease. Recommendations for disease monitoring and treatment of recurrent disease are also included. The NCCN Prostate Cancer Panel meets annually to reevaluate and update their recommendations based on new clinical data and input from within NCCN Member Institutions and from external entities. This article summarizes the panel’s discussions for the 2021 update of the guidelines with regard to systemic therapy for metastatic castration-resistant prostate cancer.

Optimal treatment sequencing of abiraterone acetate plus prednisone and enzalutamide in patients with castration-resistant metastatic prostate cancer: A systematic review and meta-analysis

PURPOSE

To evaluate the impact of the hormonal treatment sequencing including abiraterone acetate plus prednisone (AAP) and enzalutamide (ENZ) in mCRPC, and determine which sequence provides more benefits for patients.

METHODS

Studies published in English between 1 January 2013 and 30 September 2017 were identified in PubMed and EMBASE electronic databases. Studies assessing the efficacy of treatment sequences, based on AAP and ENZ, in mCRPC patients, were eligible for analysis.

RESULTS

Seventeen studies met the inclusion criteria. Two assessed both treatment sequences AAP → ENZ and ENZ → AAP; it was found that sequence of AAP → ENZ showed a statistically significantly longer PSA-PFS than the observed in ENZ → AAP (pooled HR: 0,54; 95% CI; 0,36-0,82; p < 0,05). The nine studies analysing Doc → AAP → ENZ sequence, revealed favourable results in terms of PFS. The 5 studies which analysed AAP → ENZ sequence, show a decrease in PSA levels ≥ 50% in 11-41% of patients treated with enzalutamide after previous treatment with AAP. In the two studies that analysed the Doc → ENZ → AAP sequence, PSA response rates were much lower than those reported with Doc → AAP → ENZ, with decreases in PSA ≥ 30 of 3-18% and PSA ≥ 50 of 8-11%.

CONCLUSION

Significant clinical efficacy of AAP administered as the first-line treatment in mCRPC patients followed by enzalutamide, delaying disease progression, compared with the ENZ → AAP sequence. However, more studies and randomized trials are needed, to validate the best treatment sequencing.

[Advanced prostate cancer: sequence of androgen receptor-targeted substances and chemotherapy determines long-term survival]

The treatment of advanced prostate cancer is changing. New study data and the resulting new therapeutic options have led to increasingly differentiated treatment decisions. Despite the changing therapy landscape, taxane-based chemotherapy-being a life-prolonging treatment-remains an indispensable therapeutic component for chemotherapy-fit patients in the metastatic setting. The current results of the randomized study CARD show that cabazitaxel has a higher oncological effectiveness, including a significant survival benefit and no negative impact on quality of life parameters, compared to a second androgen receptor targeted agent (ARTA) in patients with metastatic castration-resistant prostate cancer (mCRPC) who progressed after treatment with docetaxel and an androgen receptor-targeted agent (ARTA). In mCNPC the combination therapies of ADT (androgen deprivation therapy) plus docetaxel or of ADT plus ARTA have been established. In addition, three ARTAs tested in recent phase III studies in a clinical setting for patients with nonmetastatic castration-resistant prostate cancer (nmCRPC) showed that their use significantly prolongs metastasis-free survival and overall survival. The potential early use of ARTAs also has implications for the treatment of mCNPC. The aim of this publication is to provide guidance for clinical routine and to develop criteria for individual therapy decisions with a special focus on the use of chemotherapy.

The clinical benefit of sequential therapy with androgen receptor axis-targeted agents alone in patients with castration-resistant prostate cancer: A propensity score-matched comparison study

BACKGROUND

The optimal sequential therapy for castration-resistant prostate cancer (CRPC) remains unknown. In recent years, some doubts have emerged regarding the clinical benefit of sequential therapy with androgen receptor axis-targeted agents (ART) such as abiraterone (ABI) or enzalutamide (ENZ) for patients with CRPC. We compared the effect of ART-to-ART (AA) sequential therapy after castration resistance with that of docetaxel (DTX)-combined sequential therapy (ART to DTX or DTX to ART) in patients with CRPC.

METHODS

We retrospectively identified and analyzed the data of 315 patients with CRPC treated in our seven affiliated institutions between 2009 and 2019. All patients received either DTX or ART (ABI or ENZ) as the first- or second-line therapy after castration resistance. We compared the overall survival (OS) and the second progression-free survival (PFS2), calculated from the initiation of first-line therapy after castration resistance, between the AA sequence group and the DTX-combined sequence group. PFS2 was defined as the period from the start of first-line treatment after castration resistance to progression on second-line treatment. To minimize selection bias from possible confounders, we performed propensity score matching using one-to-one nearest neighbor matching without replacement.

RESULTS

Overall, 106 and 209 patients were administered the AA sequential therapy and DTX-combined sequential therapy, respectively. The clinicopathological variables of patients were well balanced after propensity score matching, and there were no significant differences between the two groups. In the propensity score-matched cohort, OS was not significantly different between the two groups (median, 37.9 vs. 45.4 months; hazard ratio [HR], 1.10; 95% confidence interval [CI], 0.68-1.79; p = .701), while PFS2 was significantly shorter in the AA group than in the DTX-combined group (median, 12.9 vs. 21.6 months; HR, 1.70; 95% CI, 1.16-2.48; p = .007).

CONCLUSIONS

Certain patients with CRPC can benefit from ART-to-ART sequential therapy in a daily clinical setting.

Circulating-tumor DNA as predictor of enzalutamide response post-abiraterone treatment in metastatic castration-resistant prostate cancer

BACKGROUND

The crossover from abiraterone acetate (AA) to enzalutamide (ENZA) is a frequent approach in clinical practice. Our aim was to explore the role of genomic alterations as putative biomarkers of response to sequential AA followed by ENZA in mCRPC and their association with clinical outcomes.

PATIENTS AND METHODS

This was a multi-center, retrospective analysis of mCRPC patients with circulating-tumor DNA (ctDNA) post-AA and prior to ENZA treatment. Objectives of this analysis were to assess PSA response, time to PSA progression (TTP) and overall survival (OS) in mCRPC patients treated with ENZA following progression on AA with respect to genomic aberrations detected by ctDNA.

RESULTS

A total of 28 patients with mCRPC were identified. Median time between AA and ENZA was 3.1 months and median initial PSA prior to ENZA was 35.0 ng/mL. Nine patients (32.1%) achieved PSA responses to ENZA. Most patients (79.0%) achieved confirmed PSA progression with median TTP of 1.6 months (95% CI, 0.7-2.4). Somatic alterations in AR genes were detected in 36.0% of patients with other common alterations detected including 39.0% TP53, 11.0% DNA repair, and 11.0% PTEN. A lack of AR alterations was associated with better PSA response to ENZA (p = 0.04).

CONCLUSION

While lack of AR alterations in ctDNA was associated with more favorable outcomes, the present dataset is insufficient to recommend the use of ctDNA to impact clinical decision-making in this setting. Further understanding of the implications of the genomic phenotype in ctDNA of castration-resistant tumors and the potential therapeutic implications is required.

Pharmacotherapeutic strategies for castrate-resistant prostate cancer

INTRODUCTION

Metastatic castration-resistant prostate cancer (CRPC) is a potentially symptomatic disease with an eventual lethal outcome. Novel pharmaceutical agents are continuously studied with encouraging results in CRPC.

AREAS COVERED

In this perspective, the authors present established and promising pharmacotherapeutic strategies for the management of CRPC; both with and without metastases. Apart from the different treatment strategies, the authors present the relevant sequence of treatment through disease progression.

EXPERT OPINION

Usually, docetaxel should be considered the first line treatment in mCRPC. Abiraterone acetate (AA) plus prednisone or enzalutamide (ENZ) could be alternative treatments in chemotherapy naïve patients. Sipuleucel-T has been approved for the treatment of asymptomatic or minimally symptomatic mCRPC. Ra-223 has been approved for patients with mCRPC with symptomatic bone metastases (not visceral metastases). Cabazitaxel has been approved as the second line treatment to docetaxel in mCRPC. No differences in the overall survival has been observed between sequences starting with docetaxel versus AA/ENZ. Between AA-to-ENZ and ENZ-to-AA sequence, the AA-to-ENZ sequence appeared to be more favorable than the ENZ-to-AA regarding progression-free survival but not overall survival. Carbazitaxel seemed to retain its activity regardless of the treatment sequence. Of note, ENZ and apalutamide have been approved in non-metastatic CRPC.

Cross-Resistance Among Next-Generation Antiandrogen Drugs Through the AKR1C3/AR-V7 Axis in Advanced Prostate Cancer

The next-generation antiandrogen drugs, XTANDI (enzalutamide), ZYTIGA (abiraterone acetate), ERLEADA (apalutamide) and NUBEQA (darolutamide) extend survival times and improve quality of life in patients with advanced prostate cancer. Despite these advances, resistance occurs frequently and there is currently no definitive cure for castration-resistant prostate cancer. Our previous studies identified that similar mechanisms of resistance to enzalutamide or abiraterone occur following treatment and cross-resistance exists between these therapies in advanced prostate cancer. Here, we show that enzalutamide- and abiraterone-resistant prostate cancer cells are further cross-resistant to apalutamide and darolutamide. Mechanistically, we have determined that the AKR1C3/AR-V7 axis confers this cross-resistance. Knockdown of AR-V7 in enzalutamide-resistant cells resensitize cells to apalutamide and darolutamide treatment. Furthermore, targeting AKR1C3 resensitizes resistant cells to apalutamide and darolutamide treatment through AR-V7 inhibition. Chronic apalutamide treatment in C4-2B cells activates the steroid hormone biosynthesis pathway and increases AKR1C3 expression, which confers resistance to enzalutamide, abiraterone, and darolutamide. In conclusion, our results suggest that apalutamide and darolutamide share similar resistant mechanisms with enzalutamide and abiraterone. The AKR1C3/AR-V7 complex confers cross-resistance to second-generation androgen receptor-targeted therapies in advanced prostate cancer.

Role of CYP3A5 in Modulating Androgen Receptor Signaling and Its Relevance to African American Men with Prostate Cancer

Androgen receptor signaling is crucial for prostate cancer growth and is positively regulated in part by intratumoral CYP3A5. As African American (AA) men often carry the wild type CYP3A5 and express high levels of CYP3A5 protein, we blocked the wild type CYP3A5 in AA origin prostate cancer cells and tested its effect on androgen receptor signaling. q-PCR based profiler assay identified several AR regulated genes known to regulate AR nuclear translocation, cell cycle progression, and cell growth. CYP3A5 processes several commonly prescribed drugs and many of these are CYP3A5 inducers or inhibitors. In this study, we test the effect of these commonly prescribed CYP3A5 inducers/inhibitors on AR signaling. The results show that the CYP3A5 inducers promoted AR nuclear translocation, downstream signaling, and cell growth, whereas CYP3A5 inhibitors abrogated them. The observed changes in AR activity is specific to alterations in CYP3A5 activity as the effects are reduced in the CYP3A5 knockout background. Both the inducers tested demonstrated increased cell growth of prostate cancer cells, whereas the inhibitors showed reduced cell growth. Further, characterization and utilization of the observation that CYP3A5 inducers and inhibitors alter AR signaling may provide guidance to physicians prescribing CYP3A5 modulating drugs to treat comorbidities in elderly patients undergoing ADT, particularly AA.

Comprehensive Analysis of AR Alterations in Circulating Tumor DNA from Patients with Advanced Prostate Cancer

BACKGROUND

Somatic alterations in circulating tumor DNA (ctDNA) may be associated with treatment response or prognosis in prostate cancer (PCa). The goal was to characterize androgen receptor gene (AR) amplifications and mutations detected in ctDNA from patients with PCa and to further understand the somatic genetic heterogeneity of advanced prostate cancer.

PATIENTS AND METHODS

This study included a heterogeneous group of 892 patients with advanced PCa (predominantly castrate-resistant prostate cancer) with AR alterations detected in ctDNA that underwent next-generation sequencing of 54 to 73 genes via Guardant360 testing (Guardant Health, Inc., Redwood City, CA). Distribution and summary of AR alterations detected, the association of AR alterations with other genes, and a pathway analysis are reported.

RESULTS

The median absolute plasma copy number of AR amplifications was 3.3 (range, 1.2-165.2). Many patients had multiple AR mutations; a total of 112 unique mutations were identified in AR, including L702H (25%), T878A (14%), H875Y (11%), W742C (8%), W742L (4%), F877L (2%), and T878S (2%). Other ctDNA gene alterations in the Guardant assays included TP53 (50%), MYC (34%), BRAF (32%), PIK3CA (29%), MET (25%), CDK6 (26%), EGFR (24%), FGFR1 (21%), and APC (12%). Many of these non-AR alterations are not tissue verified in other studies. AR amplification cosegregated with alterations in MYC (p < .001), BRAF (p < .001), PIK3CA (p < .001), MET (p < .001), CDK6 (p < .001), EGFR (p < .001), FGFR1 (p = .391), and more. Alterations in APC were significantly associated with mutations in AR (p < .001).

CONCLUSION

Several AR alterations and concomitant non-AR alterations that associate with drug resistance were detected. These findings provide additional insights into the heterogeneity of advanced prostate cancer.

IMPLICATIONS FOR PRACTICE

The goal was to characterize androgen receptor gene (AR) amplifications and mutations detected in circulating tumor DNA (ctDNA) from patients with prostate cancer in relation to non-AR gene alterations detected in the ctDNA landscape. The study included 892 patients with prostate cancer with AR alterations in ctDNA. AR alterations were significantly associated with other gene alterations detected in ctDNA. The common AR mutations found are linked to resistance to abiraterone, enzalutamide, or bicalutamide. Characterization of the circulating AR landscape and gene alterations provides potential additional insight into the somatic genetic heterogeneity of advanced prostate cancer.

Intravenous delivery of enzalutamide based on high drug loading multifunctional graphene oxide nanoparticles for castration-resistant prostate cancer therapy

BACKGROUND

Enzalutamide (Enz) has shown limited bioavailability via oral administration. Castration-resistant prostate cancer (CRPC) is frequent among patients receiving 18-24 months of androgen deprivation therapy. The nonsteroidal anti-androgen enzalutamide (Enz) used in the treatment of prostate cancer has shown limited bioavailability via oral administration. Therefore, we developed a multifunctional enzalutamide-loaded graphene oxide nanosystem (TP-GQDss/Enz) for CRPC intravenous treatment, with high drug loading efficiency.

METHODS

Aminated graphene quantum dots (GQDs) were first cross-linked via disulfide bonds into a graphene quantum dot derivative of approximately 200 nm (GQDss), which was further functionalized with a tumour-targeting peptide and PEG to form TP-GQDss. Enz was loaded into TP-GQDss for in vitro and in vivo study.

RESULTS

The results showed that high drug-loading efficiency was achieved by TP-GQDss via π-π electron interaction. TP-GQDss could be rapidly internalized by CRPC cells via endocytosis. Moreover, Enz in TP-GQDss could inhibit the growth of C4-2B and LNCaP prostate cancer cell lines in vitro. Further, TP-GQDss exhibited an enhanced cancer-targeting ability and alleviated the side effects of Enz in vivo.

CONCLUSIONS

The multifunctional nanocarrier constructed here could accomplish controlled Enz release and serve as an intravenous therapy platform for CRPC.

Comparison of Oncologic Outcomes Between Two Alternative Sequences with Abiraterone Acetate and Enzalutamide in Patients with Metastatic Castration-Resistant Prostate Cancer: A Systematic Review and Meta-Analysis

Sequential treatment of androgen receptor axis targeted agents (ARAT), abiraterone acetate (ABI) and enzalutamide (ENZA), in metastatic castration-resistant prostate cancer (mCRPC) demonstrated some positive effects, but cross-resistances between ABI and ENZA that reduce activity have been suggested. Therefore, we conducted a meta-analysis to compare oncologic outcomes between the treatment sequences of ABI-ENZA and ENZA-ABI in patients with mCRPC. The primary endpoint was a combined progression-free survival (PFS), and the secondary endpoint was overall survival (OS). A total of five trials on 553 patients were included in this study. Each of the included studies was retrospective. In two studies including both chemo-naïve and post-chemotherapy mCRPC patients, for ABI-ENZA compared with ENZA-ABI, pooled hazard ratios (HRs) for PFS and OS were 0.37 (p < 0.0001; 95% confidence intervals (CIs), 0.23–0.60) and 0.64 (p = 0.10; 95% CIs, 0.37–1.10), respectively. In three studies with chemo-naïve mCRPC patients only, for ABI-ENZA compared with ENZA-ABI, pooled HRs for PFS and OS were 0.57 (p = 0.02; 95% CIs, 0.35–0.92) and 0.86 (p = 0.39; 95% CIs, 0.61–1.21), respectively. The current meta-analysis revealed that ABI-ENZA had a significantly more favorable oncological outcome, but the level of evidence was low. Therefore, large-scale randomized trials may be needed.

Facile regiodivergent synthesis of spiro pyrrole-substituted pseudothiohydantoins and thiohydantoins via reaction of [e]-fused 1H-pyrrole-2,3-diones with thiourea

A highly divergent synthesis of regioisomeric thiohydantoins and pseudothiohydantoins spiro-fused to a pharmacologically valuable pyrrole-2-one fragment involving the reaction of [e]-fused 1H-pyrrole-2,3-diones with thioureas was developed. The obtained spiro pseudothiohydantoin derivatives were found to undergo a pseudothiohydantoin–thiohydantoin rearrangement. The reactions were shown to proceed under catalyst-free conditions in good yields, and the products were isolated without applying preparative chromatography methods.

Survival Outcomes From a Cumulative Analysis of Worldwide Observational Studies on Sequential Use of New Agents in Metastatic Castration-Resistant Prostate Cancer

INTRODUCTION

The sequential use of a number of new agents (NAs) have improved the overall survival (OS) of patients with metastatic castration-resistant prostate cancer whose disease progresses after docetaxel (DOC) treatment. The aim of this study was to assess the cumulative survival outcomes of different sequencing strategies by evaluating the individual data from published studies of patients treated with a post-DOC treatment sequence of 2 NAs.

PATIENTS AND METHODS

The patients' individual data were analyzed to investigate whether different sequencing strategies lead to differences in OS.

RESULTS

We analyzed the data of 1099 evaluable patients. Among the patients treated with a second-line new hormone agent (NHA), median OS from the start of third-line treatment was significantly longer in the patients treated with cabazitaxel (CABA) than in those treated with abiraterone acetate or enzalutamide. Median cumulative OS (cumOS) from the start of second-line treatment was 21.1 months in the patients who received NHA then NHA, 22.1 months in those who received NHA then CABA, and 21.0 months in those who received CABA then NHA. Among the patients with a second-line progression-free survival of ≥6 months, median cumOS was significantly longer in patients who received CABA-including sequences than in those treated with NHA then NHA sequences (29.5 vs. 24.8 months; P = .03).

CONCLUSION

Our findings suggest that the sequential use of NAs with different mechanisms of action improves cumOS regardless of the order in which they are administered, thus supporting the hypothesis of cross-resistance between the 2 NHAs.

Sequencing strategies in the new treatment landscape of prostate cancer

Over the last 10 years, a number of new agents approved for the treatment of metastatic castration-resistant prostate cancer have led to a significant improvement in overall survival. The addition of new agents to androgen deprivation therapy has also allowed a paradigmatic change in the treatment of metastatic hormone-sensitive prostate cancer by improving overall survival in comparison with androgen deprivation therapy alone. Furthermore, recent data concerning the efficacy of three different androgen receptor-targeting agents in patients with nonmetastatic castration-resistant prostate cancer have opened up new scenarios for future patients' management. Defining the best sequencing strategies for men with prostate cancer is a currently unmet medical need, and choosing treatment is often challenging for clinicians because of the lack of direct comparisons of the available agents. The aim of this paper is to provide a comprehensive review of the literature concerning current sequencing strategies for prostate cancer patients.

NOTCH signaling is activated in and contributes to resistance in enzalutamide-resistant prostate cancer cells

Prostate cancer is the second leading cause of cancer death among men in the United States. The androgen receptor (AR) antagonist enzalutamide is a Food and Drug Administration-approved drug for treatment of patients with late-stage prostate cancer and is currently under clinical study for early-stage prostate cancer treatment. After a short positive response period, tumors will develop drug resistance. In this study using RNA-Seq and bioinformatics analyses, we observed that NOTCH signaling is a deregulated pathway in enzalutamide-resistant cells. NOTCH2 and c-MYC gene expression positively correlated with AR expression in samples from patient with hormone refractory disease in which AR expression levels correspond to those typically observed in enzalutamide resistance. Cleaved NOTCH1, HES1 (Hes family BHLH transcription factor 1), and c-MYC protein expression levels are elevated in two enzalutamide-resistant cell lines, MR49F and C4-2R, indicating NOTCH signaling activation. Moreover, inhibition of the overexpressed ADAM metallopeptidase domain 10 (ADAM10) in the resistant cells induces an exclusive reduction in cleaved NOTCH1 expression. Furthermore, exposure of enzalutamide-resistant cells to both PF-03084014 and enzalutamide increased cell death, decreased colony formation ability, and resensitized cells to enzalutamide. Knockdown of NOTCH1 in C4-2R increased enzalutamide sensitivity by decreasing cell proliferation and increasing cleaved PARP expression. In a 22RV1 xenograft model, PF-03084014 and enzalutamide decreased tumor growth through reducing cell proliferation and increasing apoptosis. These results indicate that NOTCH1 signaling may contribute to enzalutamide resistance in prostate cancer, and inhibition of NOTCH signaling can resensitize resistant cells to enzalutamide.

Targeting AR-Beclin 1 complex-modulated growth factor signaling increases the antiandrogen Enzalutamide sensitivity to better suppress the castration-resistant prostate cancer growth

While the recently developed antiandrogen Enzalutamide (Enz) can extend survival for 4.8 months in castration-resistant prostate cancer (CRPC) patients, eventually most of these CRPC patients may develop resistance to the Enz without a clear mechanism. Here we found the expression of Beclin 1 was decreased in both Enz-resistant (EnzR) cell lines (EnzR1-C4-2 and EnzR2-C4-2B) as compared to their parental Enz-sensitive (EnzS) (EnzS1-C4-2 and EnzS2-C4-2B) cells, and targeting the Beclin 1 could lead to increase the Enz-sensitivity in these two CRPC cell lines. Mechanism dissection revealed that Enz might function via altering the interaction between Beclin 1 and the androgen receptor (AR) to decrease the activity of Beclin 1/Vps15/Vps34 complex thus increasing the ERK-mediated growth factor signaling to alter the Enz sensitivity. Interrupting the AR-Beclin 1/ERK signaling with ectopic BECN1 or ERK inhibitor led to alter the Enz sensitivity in both EnzR1-C4-2 and EnzR2-C4-2B cells compared to EnzS1-C4-2 and EnzS2-C4-2B cells, respectively. Together, these results suggest that targeting this newly identified AR-Beclin 1 complex-mediated ERK growth factor signaling with small molecule ERK inhibitor may help potentially develop new therapies to better suppress the EnzR CRPC.

Cell-based evidence regarding the role of FSH in prostate cancer

INTRODUCTION

Conversion of androgen-responsive prostate cancer (CaP) to castration-resistant CaP is associated with an acceleration of the disease that often requires treatment modalities other than androgen deprivation therapy only. Recently, follicle-stimulating hormone (FSH) has been shown to play a role in CaP growth, and clinical data showed that high serum concentration of FSH in chemically castrated CaP patients was associated with a shorter time of progression to castration-resistant CaP. In this study, we sought to investigate if FSH could have direct effects on CaP cells, possibly through the androgen receptor and androgen receptor regulated genes, such as prostate-specific antigen (PSA).

MATERIALS AND METHODS

The human CaP cell lines PC-3, LNCaP and C4-2, and nonmalignant PNT1A cells, were utilized to investigate the effects of FSH. qPCR, Western blotting analysis, and 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymetoxyphenyl)-2-(4-sulfophenyl)-2H tetrazolium assays were performed in order to analyze the FSH effects.

RESULTS

The FSH receptor was present in all cell lines except PNT1A. FSH significantly increased PSA mRNA (P < 0.01) and protein (P < 0.03) levels in C4-2 cells in a dose-dependent manner. In LNCaP cells, FSH also increased PSA protein level, although to a lesser extent than in C4-2 cells, and the expression was reduced by the antiandrogen enzalutamide. In PC-3 cells, FSH was shown to increase their proliferation (P < 0.03) and β-catenin expression.

CONCLUSION

These findings demonstrate that FSH may have a direct effect in CaP in an androgen-depleted environment. However, further research is needed to understand the significance of direct FSH action in the maintenance of CaP growth at the different phases of transition from androgen dependence to androgen independence.

Enzalutamide therapy for advanced prostate cancer: efficacy, resistance and beyond

The androgen receptor drives the growth of metastatic castration-resistant prostate cancer. This has led to the development of multiple novel drugs targeting this hormone-regulated transcription factor, such as enzalutamide – a potent androgen receptor antagonist. Despite the plethora of possible treatment options, the absolute survival benefit of each treatment separately is limited to a few months. Therefore, current research efforts are directed to determine the optimal sequence of therapies, discover novel drugs effective in metastatic castration-resistant prostate cancer and define patient subpopulations that ultimately benefit from these treatments. Molecular studies provide evidence on which pathways mediate treatment resistance and may lead to improved treatment for metastatic castration-resistant prostate cancer. This review provides, firstly a concise overview of the clinical development, use and effectiveness of enzalutamide in the treatment of advanced prostate cancer, secondly it describes translational research addressing enzalutamide response vs resistance and lastly highlights novel potential treatment strategies in the enzalutamide-resistant setting.

Current therapeutic options in metastatic castration-resistant prostate cancer

BACKGROUND

The tumors of many patients with prostate cancer eventually become refractory to androgen deprivation therapy with progression to metastatic castration-resistant disease. Significant advances in the treatment of metastatic castration-resistant prostate cancer (mCRPC) have been made in recent years, and new treatment strategies have recently been made available. The aim of this report was to schematically review all the approved pharmacologic treatment options for patients with mCRPC through 2018, analyzing the efficacy and possible side effects of each therapy to assist clinicians in reaching an appropriate treatment decision. New biomarkers potentially of aid in the choice of treatment in this setting are also briefly reviewed.

METHODS

We performed a literature search of clinical trials of new drugs and treatments for patients diagnosed with mCRPC published through 2018.

RESULTS

Two new hormonal drugs, abiraterone acetate and enzalutamide have been approved by FDA in 2011 and 2012, respectively for the treatment of patients with mCRPC and have undergone extensive testing. While these treatments have shown a benefit in progression-free and overall survival, the appropriate sequencing must still be determined so that treatment decisions can be made based on their specific clinical profile. Cabazitaxel has been shown to be an efficient therapeutic option in a postdocetaxel setting, while its role in chemotherapy-naïve patients must still be determined. Sipuleucel-T and radium-223 have been studied in patients without visceral metastases and have achieved overall survival benefits with good safety profiles. The feasibility and efficacy of combinations of new treatments with other known therapies such as chemotherapy are currently under investigation.

CONCLUSIONS

Drug development efforts continue to attempt to prolong survival and improve quality of life in the mCRPC setting, with several therapeutic options available. Ongoing and future trials are needed to further assess the efficacy and safety of these new drugs and their interactions, along with the most appropriate sequencing.

Abiraterone Alone or in Combination With Enzalutamide in Metastatic Castration-Resistant Prostate Cancer With Rising Prostate-Specific Antigen During Enzalutamide Treatment

Purpose Enzalutamide resistance could result from raised androgens and be overcome by combination with abiraterone acetate. PLATO ( ClinicalTrials.gov identifier: NCT01995513) interrogated this hypothesis using a randomized, double-blind, placebo-controlled design. Patients and Methods In period one, men with chemotherapy-naïve metastatic castration-resistant prostate cancer received open-label enzalutamide 160 mg daily. Men with no prostate-specific antigen (PSA) increase at weeks 13 and 21 were treated until PSA progression (≥ 25% increase and ≥ 2 ng/mL above nadir), then randomly assigned at a one-to-one ratio in period two to abiraterone acetate 1,000 mg daily and prednisone 5 mg twice daily with either enzalutamide or placebo (combination or control group, respectively) until disease progression as defined by the primary end point: progression-free survival (radiographic or unequivocal clinical progression or death during study). Secondary end points included time to PSA progression and PSA response in period two. Results Of 509 patients enrolled in period one, 251 were randomly assigned in period two. Median progression-free survival was 5.7 months in the combination group and 5.6 months in the control group (hazard ratio, 0.83; 95% CI, 0.61 to 1.12; P = .22). There was no difference in the secondary end points. Grade 3 hypertension (10% v 2%) and increased ALT (6% v 2%) or AST (2% v 0%) were more frequent in the combination than the control group. Conclusion Combining enzalutamide with abiraterone acetate and prednisone is not indicated after PSA progression during treatment with enzalutamide alone; hypertension and elevated liver enzymes are more frequent with combination therapy.

Evaluation of Response to Enzalutamide Consecutively After Abiraterone Acetate/Prednisone Failure in Patients With Metastatic Castration-resistant Prostate Cancer

INTRODUCTION

Treatment of metastatic castration-resistant prostate cancer (mCRPC) has evolved significantly during the past decade, and the preferred combination and/or sequence of these treatments remains controversial. In this retrospective study, we explored clinical and pathologic factors that could predict response to consecutive treatment with enzalutamide (ENZA) after disease progression (PD) on abiraterone acetate and prednisone (AA/P).

PATIENTS AND METHODS

Data were collected from 40 consecutive patients with mCRPC who were treated with ENZA without other interim therapy after progression on AA/P.

RESULTS

The median time from prostate cancer initial diagnosis to AA/P treatment was 6.2 (range, 0.9-16.3) years. The median prostate-specific antigen (PSA) progression-free survival (PSA-PFS) from treatment initiation was 8.5 months (95% confidence interval [CI], 7.1-10.1 months) and 2.3 months (95% CI, 1.8-3.4 months) on AA/P and ENZA, respectively. The median time to PD from treatment initiation was 9.7 months (95% CI, 7.1-12.4 months) and 3 months (95% CI, 2.3-4.1 months) on AA/P and ENZA, respectively. The correlations were weak between the best percent change in PSA on ENZA and time from diagnosis to AA/P initiation, best absolute or percentage change in PSA on AA/P, time to PSA progression or PD on AA/P. Patients with longer than the median duration of treatment with AA/P (11.73 months) had longer PSA-PFS on ENZA (median 2.8 vs. 1.9 months; P = .035).

CONCLUSIONS

In this retrospective analysis, we did not find any clinical or pathologic factors associated with response to ENZA administered consecutively after AA/P. Patients with longer than median AA/P treatment duration had longer PSA-PFS on ENZA. Further evaluations and validation are greatly needed.

Evaluating the Benefits of New Drugs in Health Technology Assessment Using Multiple Criteria Decision Analysis: A Case Study on Metastatic Prostate Cancer With the Dental and Pharmaceuticals Benefits Agency (TLV) in Sweden

Background. Multiple criteria decision analysis (MCDA) has been identified as a prospective methodology for assisting decision makers in evaluating the benefits of new medicines in health technology assessment (HTA); however, limited empirical evidence exists from real-world applications. Objective. To test in practice a recently developed MCDA methodological framework for HTA, the Advance Value Framework, in a proof-of-concept case study with decision makers. Methods. A multi-attribute value theory methodology was adopted applying the MACBETH questioning protocol through a facilitated decision-analysis modelling approach as part of a decision conference with four experts. Settings. The remit of the Swedish Dental and Pharmaceutical Benefits Agency (Tandvårds- och läkemedelsförmånsverket [TLV]) was adopted but in addition supplementary value dimensions were considered. Patients. Metastatic castrate-resistant prostate cancer patients were considered having received prior chemotherapy. Interventions. Abiraterone, cabazitaxel, and enzalutamide were evaluated as third-line treatments. Measurements. Participants’ value preferences were elicited involving criteria selection, options scoring, criteria weighting, and their aggregation. Results. Eight criteria attributes were finally included in the model relating to therapeutic impact, safety profile, socioeconomic impact, and innovation level with relative importance weights 44.5%, 33.3%, 14.8%, and 7.4% per cluster, respectively. Enzalutamide scored the highest overall weighted preference value score, followed by abiraterone and cabazitaxel. Dividing treatments’ overall weighted preference value scores by their costs derived “costs per unit of value” for ranking the treatments based on value-for-money grounds. Limitations. Study limitations included lack of comparative clinical effects across treatments and the small sample of participants. Conclusion. The Advance Value Framework has the prospects of facilitating the evaluation process in HTA and health care decision making; additional research is recommended to address technical challenges and optimize the use of MCDA for policy making.

IL-23 secreted by myeloid cells drives castration-resistant prostate cancer

Patients with prostate cancer frequently show resistance to androgen-deprivation therapy, a condition known as castration-resistant prostate cancer (CRPC). Acquiring a better understanding of the mechanisms that control the development of CRPC remains an unmet clinical need. The well-established dependency of cancer cells on the tumour microenvironment indicates that the microenvironment might control the emergence of CRPC. Here we identify IL-23 produced by myeloid-derived suppressor cells (MDSCs) as a driver of CRPC in mice and patients with CRPC. Mechanistically, IL-23 secreted by MDSCs can activate the androgen receptor pathway in prostate tumour cells, promoting cell survival and proliferation in androgen-deprived conditions. Intra-tumour MDSC infiltration and IL-23 concentration are increased in blood and tumour samples from patients with CRPC. Antibody-mediated inactivation of IL-23 restored sensitivity to androgen-deprivation therapy in mice. Taken together, these results reveal that MDSCs promote CRPC by acting in a non-cell autonomous manner. Treatments that block IL-23 can oppose MDSC-mediated resistance to castration in prostate cancer and synergize with standard therapies.

Recent advances on the progressive mechanism and therapy in castration-resistant prostate cancer

Background

Although there have been great advances in mechanisms and therapeutic methods of prostate cancer, the mortality rate of prostate cancer remains high. The castration-resistant prostate cancer (CRPC), which develops from hormone-sensitive prostate cancer, foreshadows a more dismal outcome. Concomitant with the researches in the mechanism of CRPC and therapy for CRPC, more and more landmark progress has been made in recent years.

Methods

A number of clinical and experimental studies were reviewed to indicate the novel advancement in the progressive mechanism and therapy of CRPC.

Results

The androgen receptor (AR) is still a vital driver in the progression of CRPC, while other multiple mechanisms also contribute to this progression, such as tumor immunity, cancer stem cells, epithelial–mesenchymal transition and DNA repair disorder. In terms of the therapeutic methods of CRPC, chemotherapy with drugs, such as docetaxel, has been the first-line therapy for CRPC for many years. Besides, newer agents, which target some of the above mechanisms, show additional overall survival benefits for CRPC patients. These therapies include drugs targeting the androgen axis pathway (androgen synthesis, androgen receptor splice variants, coactivators of AR and so on), PI3K-AKT pathway, WNT pathway, DNA repair, rearrangement of ETS gene, novel chemotherapy and immunotherapy, bone metastasis therapy and so on. Understanding these novel findings on the mechanisms of CRPC and the latest potential CRPC therapies will direct us for further exploration of CRPC.

Conclusion

Through comprehensive consideration, the predominant mechanism of CRPC might be the AR signal axis concomitant with tumor microenvironment, stress, immunity, tumor microenvironment and so on. For CRPC therapy, targeting the AR axis pathway and chemotherapy are the first-line treatments at present. However, with the advancements in CRPC therapy made by the researchers, other novel potential methods will occupy more and more important position in the treatment of CRPC, especially the therapies targeting the tumor microenviroment, tumor immunity and DNA repair and so on.

Radium-223 in the therapeutic sequence of metastatic castration-resistant prostate cancer

CONTEXT

Radium-223 is an □ -particle transmitter with specific action on bone metastases. The Alpharadin in Symptomatic Prostate Cancer Patients (ALSYMPCA) study showed that radium-223 extended overall survival and delayed the onset of bone events in patients with symptomatic castration-resistant prostate cancer with bone metastases (mCRPC) and without visceral metastases, with a good safety profile.

OBJECTIVE

To review the new scientific evidence on radium-223 based on prespecified and post-hoc analyses of the ALSYMPCA study and on early-access programs after the publication of the ALSYMPCA study, thereby providing new data on the management of patients with mCRPC.

ACQUISITION OF EVIDENCE

We searched for evidence on PubMed and in the abstracts of international urology and oncology congresses, as well as ongoing clinical trials (ClinicalTrials.gov).

SYNTHESIS OF THE EVIDENCE

The results of the reviewed studies offer promising results that will broaden the therapeutic benefits of radium-223 to patients with mild symptoms and those with no symptoms. The results also provide preliminary evidence on the benefit of radium-223 treatment after the failure of docetaxel, enzalutamide or abiraterone or the combination of radium-223 with these agents or other therapeutic agents such as bone-targeted agents and immunotherapy.

CONCLUSION

Radium-223 can be a treatment option for patients with mild symptoms and can provide a therapeutic benefit after failure of currently available treatments or in combination with these treatments. This evidence should be corroborated in clinical trials before being added to clinical practice.

Efficacy and safety of different interventions in castration resistant prostate cancer progressing after docetaxel-based chemotherapy: Bayesian network analysis of randomized controlled trials

Background: Most patients receiving docetaxel-based chemotherapy for castration resistant prostate cancer (CRPC) will eventually progress, and the optimal interventions for these patients are controversial. The objective of our study is to evaluate the clinical efficacy and safety of pharmacological interventions for CRPC patients progressing after docetaxel-based chemotherapy.

Methods: A systematic review and Bayesian network meta-analysis of the literature was carried out according to standard methods. Major electronic databases including PubMed, Web of Science and Embase were searched until Jan 2017. Hazard ratios (HRs) and odds ratios (ORs) with corresponding 95% credible intervals (CrIs) were used to estimate the association.

Results: 17 Randomized Controlled Trials (RCTs) comprising 14 different interventions with 12347 patients were enrolled. Compared with control arms, Abiraterone Acetate (HR: 0.70, 95%CrI: 0.63-0.79), Cabazitaxel (HR: 0.70, 95%CrI: 0.51-0.95) and Enzalutamide (HR: 0.63, 95%CrI: 0.53-0.75) presented similar benefits in term of OS. Enzalutamide showed superiority over PFS and PSA response with a highest probability to rank 1. Moreover, sensitivity analysis showed that Abiraterone Acetate (HR: 0.71, 95%CrI: 0.63-0.78) exhibited the most efficacious intervention of being rank 1 in term of OS compared with control arms, followed by Cabazitaxel and Cetuximab. On the other hand, Abiraterone Acetate (OR: 0.86, 95%CrI: 0.35-2.03) presented no significant toxicities compared with control arms.

Conclusions: Our results demonstrated that Abiraterone Acetate might be the optimal intervention for CRPC patients after docetaxel failure with acceptable tolerability. Future well-designed RCTs and systematic reviews are needed to validate these findings.

Platelets harbor prostate cancer biomarkers and the ability to predict therapeutic response to abiraterone in castration resistant patients

BACKGROUND

Novel therapies for castration resistant prostate cancer (CRPC) have been introduced in the clinic with possibilities for individualized treatment plans. Best practice of those expensive drugs requires predictive biomarker monitoring. This study used circulating biomarker analysis to follow cancer-derived transcripts implicated in therapy resistance.

METHOD

The isolated platelet population of blood samples and digital-PCR were used to identify selected biomarker transcripts in patients with CRPC prior chemo- or androgen synthesis inhibiting therapy.

RESULTS

Fifty patients received either docetaxel (n = 24) or abiraterone (n = 26) therapy, with therapy response rates of 54% and 48%, respectively. Transcripts for the PC-associated biomarkers kallikrein-related peptidase-2 and -3 (KLK2, KLK3), folate hydrolase 1 (FOLH1), and neuropeptide-Y (NPY) were uniquely present within the platelet fraction of cancer patients and not detected in healthy controls (n = 15). In the abiraterone treated cohort, the biomarkers provided information on therapy outcome, demonstrating an association between detectable biomarkers and short progression free survival (PFS) (FOLH1, P < 0.01; KLK3, P < 0.05; and NPY, P < 0.05). Patients with biomarker-negative platelets had the best outcome, while FOLH1 (P < 0.05) and NPY (P = 0.05) biomarkers provided independent predictive information in a multivariate analysis regarding PFS. KLK2 (P < 0.01), KLK3 (P < 0.001), and FOLH1 (P < 0.05) biomarkers were associated with short overall survival (OS). Combining three biomarkers in a panel (KLK3, FOLH1, and NPY) made it possible to separate long-term responders from short-term responders with 87% sensitivity and 82% specificity.

CONCLUSION

Analyzing tumor-derived biomarkers in platelets of CRPC patients enabled prediction of the outcome after abiraterone therapy with higher accuracy than baseline serum PSA or PSA response.