Sequencing Treatment for Castration-Resistant Prostate Cancer

Based on network pharmacology and molecular docking to predict the mechanism of Huangqi in the treatment of castration-resistant prostate cancer

Background

As a kind of traditional Chinese medicine, HQ is widely mentioned in the treatment of cancerous diseases in China, which has been proven to have a therapeutic effect on cancerous diseases, such as prostate cancer. To predict the specific mechanism of HQ in the treatment of CRPC, we will conduct preliminary verification and discussion based on a comprehensive consideration of network pharmacology and molecular docking.

Methods

TCMSP was used to obtain the compounds and reach the effective targets of HQ. The targets of CRPC were reached based on GeneCards database and CTD database. GO and KEGG were utilized for the analysis of overlapping targets. The software of Openbabel was used to convert the formats of ligands and reporters. In addition, molecular docking studies were performed by using the software of Autodock Vina.

Result

It can be seen from the database results that there were 87 active compounds (20 key active compounds) in HQ, and 33 targets were screened out for CRPC treatment. GO and KEGG pathway enrichment analyses identified 81 significant GO terms and 24 significant KEGG pathways. There is a difference in terms of the expression of core protein between cancer patients and healthy people. The expression of core protein in patients also has an impact on the life cycle. The results of molecular docking showed that the docking activity of drug molecules and core proteins was better.

Conclusions

It is concluded from the results of this network pharmacology and molecular docking that HQ makes a multi-target and multi-biological process, and results in the multi-channel synergistic effect on the treatment of CRPC by regulating cell apoptosis, proliferation and metastasis, which still needs further verification by experimental research.

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.

Predicting toxicity-related docetaxel discontinuation and overall survival in metastatic castration-resistant prostate cancer: a pooled analysis of open phase 3 clinical trial data

BACKGROUND

Docetaxel is widely used in metastatic castration-resistant prostate cancer (mCRPC), however its optimal use remains unclear in the current treatment landscape. Biomarkers to predict Docetaxel toxicity may help optimize treatment selection. We aimed to create a predictive model for toxicity-related Docetaxel discontinuation (TRDD).

METHODS

Through Project Data Sphere, we accessed individual patient data from the control arms of three frontline mCRPC trials: ASCENT2, VENICE, and MAINSAIL. The inclusion criteria for these trials were all similar and included patients with chemotherapy-naïve mCRPC. The primary outcome was occurrence of TRDD. A competing risks regression (CRR) was used to predict TRDD, after accounting for the occurrence of competing events (death or progression). The output of the model was used as the dependent variable on a classification and regression tree (CART) to identify risk groups for TRDD.

RESULTS

Overall, 1568 patients were considered. Pooled CI of TRDD was 19% after accounting for competing events (death: 474; progression: 59) within 12 months of starting treatment. To build a risk calculator we relied on a CRR that ultimately included age, ECOG performance status, AST, bilirubin, use of analgesics, and presence of diabetes and chronic kidney disease. The CART analysis identified three risk groups that were named: low (model-derived TRDD risk ≤24%), intermediate (25-64%), and high (≥65%) risk group. In each risk group, probability of TRDD during treatment was 14%, 58%, and 79%, and median OS was 24 months, 20 months, and 13 months, respectively (p < 0.001).

CONCLUSIONS

Treatment selection in mCRPC remains a challenge. Our model can help clinicians balance Docetaxel toxicity and efficacy. The three risk categories that we identified correlated with OS and this is particularly useful for an optimal shared decision-making process.

Immune checkpoint B7-H3 protein expression is associated with poor outcome and androgen receptor status in prostate cancer

BACKGROUND

Novel immune checkpoint-based immunotherapies may benefit specific groups of prostate cancer patients who are resistant to other treatments.

METHODS

We analyzed by immunohistochemistry the expression of B7-H3, PD-L1/B7-H1, and androgen receptor (AR) in tissue samples from 120 prostate adenocarcinoma patients treated with radical prostatectomy in Spain, and from 206 prostate adenocarcinoma patients treated with radical prostatectomy in Norway.

RESULTS

B7-H3 expression correlated positively with AR expression and was associated with biochemical recurrence in the Spanish cohort, but PD-L1 expression correlated with neither of them. Findings for B7-H3 were validated in the Norwegian cohort, where B7-H3 expression correlated positively with Gleason grade, surgical margins, seminal vesicle invasion, and CAPRA-S risk group, and was associated with clinical recurrence. High B7-H3 expression in the Norwegian cohort was also consistent with positive AR expression.

CONCLUSION

These results suggest distinct clinical relevance of the two immune checkpoint proteins PD-L1 and B7-H3 in prostate cancer. Our findings highlight B7-H3 as an actionable novel immune checkpoint protein in prostate cancer.

Treatment-Related Healthcare Costs of Metastatic Castration-Resistant Prostate Cancer in Germany: A Claims Data Study

PURPOSE

Treatments for patients with metastatic castration-resistant prostate cancer (mCRPC) have expanded rapidly. They include the chemotherapies docetaxel and cabazitaxel, hormonal drugs abiraterone and enzalutamide, and best supportive care (BSC). Cabazitaxel has proven to be the last life-prolonging option, associated with a significant risk of serious adverse events. Given the lack of real-world evidence, we aimed to compare healthcare resource utilization (HRU) and costs in patients with mCRPC treated with cabazitaxel, docetaxel, abiraterone, enzalutamide, and BSC.

METHODS

We used 2014-2017 claims data from a large German statutory health insurance fund, the Techniker Krankenkasse, to identify patients with mCRPC. Patient allocation to individual therapy regimens was based on clinical knowledge and included therapy cycles, duration of therapy, and continuous treatment. The study period lasted from the first claim until death, the end of data availability, a drug switch, or discontinuation of therapy, whichever came first. Multivariate regression models were used to compare monthly all-cause and mCRPC-related HRU and costs across cohorts by adjusting for baseline covariates (including age and comorbidities).

RESULTS

The 3944 identified patients with mCRPC initiated treatment with cabazitaxel (n = 240), docetaxel (n = 539), abiraterone (n = 486), enzalutamide (n = 351), or BSC (n = 2328). In most domains, HRU was highest in the cabazitaxel cohort and lowest in the BSC group. Accordingly, the highest all-cause and mCRPC-related costs per month, respectively, were observed in patients receiving cabazitaxel (€7631/€6343), followed by abiraterone (€5226/€4579), enzalutamide (€5079/€4416), docetaxel (€2392/€1580), and BSC (€959/€438). Cost variations were mostly attributable to drugs, inpatient treatment, and sick leave payments.

CONCLUSION

mCRPC treatment imposes a high economic burden on statutory health insurance. Cabazitaxel is associated with substantially higher expenses, resulting from higher drug costs and a greater need for inpatient treatment. As mCRPC continues to be incurable, decision makers and clinician leaders should carefully evaluate public access to innovative agents and optimal treatment strategies.

Resistance to second-generation androgen receptor antagonists in prostate cancer

The introduction of second-generation androgen receptor antagonists (SG-ARAs) has greatly impacted the treatment of metastatic prostate cancer, providing tolerable and efficacious alternatives to chemotherapy. SG-ARAs provide similar therapeutic benefit to abiraterone, a potent CYP17 inhibitor, and do not require the co-administration of prednisone. Despite considerable improvements in clinical outcomes in the settings of both castration sensitivity and castration resistance, the durability of clinical response to the SG-ARAs enzalutamide, apalutamide and darolutamide, similar to abiraterone, is limited by inevitable acquired resistance. Genomic aberrations that confer resistance to SG-ARAs or provide potential alternative treatment modalities have been identified in numerous studies, including alterations of the androgen receptor, DNA repair, cell cycle, PI3K-AKT-mTOR and Wnt-β-catenin pathways. To combat resistance, researchers have explored approaches to optimizing the utility of available treatments, as well as the use of alternative agents with a variety of targets, including AR-V7, AKT, EZH2 and HIF1α. Ongoing research to establish predictive biomarkers for the treatment of tumours with resistance to SG-ARAs led to the approval of the PARP inhibitors olaparib and rucaparib in pre-treated metastatic castration-resistant prostate cancer. The results of ongoing studies will help to shape precision medicine in prostate cancer and further optimize treatment paradigms to maximize clinical outcomes.

What Do Men with Metastatic Prostate Cancer Consider When Making Treatment Decisions? A Mixed-methods Study

OBJECTIVE

Metastatic prostate cancer (mPCa) patients often make complicated treatment decisions, yet decision aids to facilitate shared decision-making for mPCa are uncommon. To inform the development of patient-centered mPCa decision aids, we examined what mPCa survivors considered most important when making treatment decisions.

METHODS

Using an exploratory sequential approach, we conducted three focus groups with 14 advanced prostate cancer survivors (n=5, n=3, n=6 in each group) to identify considerations for making treatment decisions. Focus groups were audio-recorded and transcribed, and we identified qualitative themes. We then developed a quantitative survey to assess the importance of each theme and administered the survey to mPCa survivors (N=100). We used relative frequencies to determine the most strongly endorsed items and chi-squared and Fisher's exact tests to assess associations with participant characteristics.

RESULTS

Focus groups yielded 11 themes, and the resulting survey included 20 items. The most strongly endorsed mPCa treatment considerations were: relying on physician's treatment recommendations (79% strongly agree); wanting to feel well enough to spend quality time with loved ones (72% strongly agree); the importance of dying in a manner consistent with one's wishes (70% strongly agree); hoping to eliminate cancer completely (68% strongly agree); and optimizing treatment efficacy (65% strongly agree). Age, race, marital status, employment status, and self-reported health were related to how strongly men endorsed various considerations for mPCa treatment decision-making.

CONCLUSION

We identified multiple considerations that mPCa survivors appraised when making treatment decisions. These data may inform the development of patient-centered decision aids for mPCa.

Decreased biochemical progression in patients with castration-resistant prostate cancer using a novel mefenamic acid anti-inflammatory therapy: A randomized controlled trial

Prostate cancer (PCa) is the second most common non-dermatological cancer in men and is a growing public health problem. Castration-resistant disease (CRD) is the most advanced stage of the disease and is difficult to control. Patients with CRD may no longer accept conventional therapies as they are not in appropriate clinical conditions or they refuse to receive it. Given that inflammation is an essential component of CRD origin and progression, anti-inflammatory agents could be a therapeutic option with fenamates as one of the proposed choices. A prospective, randomized, double-blinded, 2-arm, parallel group, phase II-III clinical trial was performed involving 20 patients with CRD-PCa (with a prostate specific antigen level <100 ng/ml) that were undergoing androgen deprivation therapy (ADT) and did not accept any established treatment for that disease stage. In addition to ADT, 10 patients received placebo and 10 received mefenamic acid (500 mg orally every 12 h) for 6 months. The primary endpoint was the change in serum prostate-specific antigen (PSA) at 6 months. The PSA levels decreased significantly with mefenamic acid (an average 42% decrease), whereas there was an average 55% increase in the placebo group (P=0.024). In the patients treated with the placebo, 70% had biochemical disease progression (an increase of ≥25% in PSA levels), which did not occur in any of the patients treated with mefenamic acid (relative risk=0.12; 95% confidence interval, 0.01-0.85; P=0.033). There was a significant increase in quality of life (EQ-5D-5L score) and body mass index (BMI) with the experimental treatment. In conclusion, mefenamic acid administration decreased biochemical progression in patients with castration resistant PCa, improved their quality of life and increased their BMI. Future studies are required in order to strengthen the findings of the present clinical trial. Trial registration, Cuban Public Registry of Clinical Trials Database RPCEC00000248, August 2017.

Monitoring dynamic cytotoxic chemotherapy response in castration-resistant prostate cancer using plasma cell-free DNA (cfDNA)

Objective

Cell-free DNA (cfDNA) is an attractive cancer biomarker, as it is thought to reflect a component of the underlying genetic makeup of the tumor and is readily accessible in serial fashion. Because chemotherapy regimens are expected to act rapidly on cancer and cfDNA is cleared from the blood within minutes, we hypothesized that cfDNA would reflect immediate effects of treatment. Here, we developed a method for monitoring long cfDNA fragments, and report dynamic changes in response to cytotoxic chemotherapy.

Results

Peripheral blood was obtained from 15 patients with metastatic castration-resistant prostate cancer (CRPC) immediately before and after cytotoxic chemotherapy infusion. cfDNA was extracted and quantified for long interspersed nuclear elements (LINE1; 297 bp) using qPCR. Targeted deep sequencing was performed to quantify the frequency of mutations in exon 8 of the androgen receptor (AR), a mutational hotspot region in CRPC. Single nucleotide mutations in AR exon 8 were found in 6 subjects (6/15 = 40%). Analytical variability was minimized by pooling independent PCR reactions for each library. In 5 patients, tumor-derived long cfDNA levels were found to change immediately after infusion. Detailed analysis of one subject suggests that cytotoxic chemotherapy can produce rapidly observable effects on cfDNA.

Electronic supplementary material

The online version of this article (10.1186/s13104-019-4312-2) contains supplementary material, which is available to authorized users.

Stereotactic ablative radiation therapy for oligometastatic prostate cancer delays time-to-next systemic treatment

PURPOSE

Local ablative treatment to oligometastatic patients can result in long-term disease-free survival in some cancer patients. The importance of this treatment paradigm in prostate cancer is a rapidly evolving field. Herein, we report on the safety and preliminary clinical outcomes of a modern cohort of oligometastatic prostate cancer (OPC) patients treated with consolidative stereotactic ablative radiation (SABR).

METHODS

Records of men with OPC who underwent consolidative SABR at our institution were reviewed. SABR was delivered in 1-5 fractions of 5-18 Gray. Kaplan-Meier estimates of local progression-free survival (LPFS), biochemical progression-free survival (bPFS; PSA nadir + 2), distant progression-free survival (DPFS), and time-to-next intervention (TTNI) were calculated.

RESULTS

In total, 66 OPC patients were identified with consolidative SABR delivered to 134 metastases: 89 bone, 40 nodal, and 5 viscera. The majority of men (49/66) had hormone-sensitive prostate cancer (HSPC). Crude grade 1 and 2 acute toxicities were 36% and 11%, respectively, with no ≥ grade 3 toxicity. At 1 year, LPFS was 92% and bPFS and DPFS were 69%. Of the 18 men with HSPC who had deferred hormone therapy , 11 (56%) remain disease free following SABR (1-year ADT-FS was 78%). In 17 castration-resistant men, 11 had > 50% prostate-specific antigen (PSA) declines with 1-year TTNI of 30%.

CONCLUSIONS

Consolidative SABR in OPC is feasible and well tolerated. The heterogeneity and small size of our series limit extrapolation of clinically meaningful outcomes following consolidative SABR in OPC, but our preliminary data suggest that this approach warrants continued prospective study.

Castration-Resistant Prostate Cancer: Sequencing Oral and Infusion Agents

PURPOSE OF REVIEW

To update treatment options and considerations for castration-resistant prostate cancer with specific attention to sequencing of agents based on available evidence and treatment rationale.

RECENT FINDINGS

The newest research developments over the last several years include multicenter studies that address the sequencing of therapies to improve the treatment of metastatic castration-resistant prostate cancer. Chemotherapy agents, as well as androgen receptor antagonists, are evolving, and there are new tests available to define which patients are more likely to benefit. In addition, there have been some additional trials looking into the safety and efficacy of combination treatment and new therapies. There are multiple factors that should be considered to determine the sequence and/or combinations of therapies for metastatic castration-resistant prostate cancer that can improve quality of life and survival. Promising novel agents in combination with personalized medicine will likely continue to improve treatment of these patients.

Intra versus Inter Cross-resistance Determines Treatment Sequence between Taxane and AR-Targeting Therapies in Advanced Prostate Cancer

Current treatments for castration resistant prostate cancer (CRPC) largely fall into two classes: androgen receptor (AR)-targeted therapies such as the next-generation antiandrogen therapies (NGAT), enzalutamide and abiraterone, and taxanes such as docetaxel and cabazitaxel. Despite improvements in outcomes, patients still succumb to the disease due to the development of resistance. Further complicating the situation is lack of a well-defined treatment sequence and potential for cross-resistance between therapies. We have developed several models representing CRPC with acquired therapeutic resistance. Here, we utilized these models to assess putative cross-resistance between treatments. We find that resistance to enzalutamide induces resistance to abiraterone and vice versa, but resistance to neither alters sensitivity to taxanes. Acquired resistance to docetaxel induces cross-resistance to cabazitaxel but not to enzalutamide or abiraterone. Correlating responses with known mechanisms of resistance indicates that AR variants are associated with resistance to NGATs, whereas the membrane efflux protein ABCB1 is associated with taxane resistance. Mechanistic studies show that AR variant-7 (AR-v7) is involved in NGAT resistance but not resistance to taxanes. Our findings suggest the existence of intra cross-resistance within a drug class (i.e., within NGATs or within taxanes), whereas inter cross-resistance between drug classes does not develop. Furthermore, our data suggest that resistance mechanisms differ between drug classes. These results may have clinical implications by showing that treatments of one class can be sequenced with those of another, but caution should be taken when sequencing similar classed drugs. In addition, the development and use of biomarkers indicating resistance will improve patient stratification for treatment. Mol Cancer Ther; 17(10); 2197-205. ©2018 AACR.

PARP inhibitors for homologous recombination-deficient prostate cancer

INTRODUCTION

Prostate adenocarcinoma represents a leading cause of cancer-related mortality. Increased emphasis on understanding the molecular basis of prostate cancer has identified a substantial burden of homologous recombination (HR) pathway mutations, which are enriched in castrate-resistant disease. This discovery has yielded novel therapeutic opportunities. Areas covered: We will discuss the treatment of castrate-resistant prostate cancer (CRPC), with a focus on the use of poly (ADP-ribose) polymerase (PARP) inhibitors in this space. Evidence for use in HR-deficient patients will be outlined with discussion of the mechanism of action for this drug class, pathways of resistance, and approaches for expanding PARP inhibitor use to non-HR-deficient prostate cancer subgroups. Expert opinion: PARP inhibition represents an exciting tool for management of HR-inactivated CRPC. With rapid adoption of next-generation sequencing technologies and other molecular techniques, the number of patients in this category is likely to increase. Ongoing and future investigations will be critical for improved understanding of the promise and appropriate treatment sequencing of PARP inhibition and optimal options for HR-proficient and -deficient prostate cancer populations. Questions remain about the clinical significance of monoallelic vs. biallelic HR mutations, the relevance of germline vs. somatic-only mutations, and the importance of mutations in non-canonical HR genes.

CTC-derived AR-V7 detection as a prognostic and predictive biomarker in advanced prostate cancer

INTRODUCTION

Prostate cancer is a highly heterogeneous disease, with remarkably different prognosis across all stages. Increased circulating tumor cell (CTC) count (≥ 5) using the CellSearch assay has been identified as one of the markers that can be used to predict survival, with added value beyond currently available prognostic factors. Recently, androgen receptor splice variant 7 (AR-V7) detection has been associated with worse outcomes for patients with castration-resistant prostate cancer (CRPC) treated with novel androgen receptor-signaling (ARS) inhibitors such as abiraterone and enzalutamide but not taxane chemotherapies. Areas covered: In this manuscript, the authors review the available biomarkers in CRPC and discuss emerging data on the value of CTC-derived AR-V7 status to assess prognosis and its potential role to guide treatment selection for patients with advanced prostate cancer. Expert commentary: Current evidence supports AR-V7 status as a prognostic biomarker and also as a potential predictive biomarker for patients with mCRPC. The authors expect that the incorporation of AR-V7 status and other biomarkers (e.g. AR mutations) in the sequential assessment of patients with advanced prostate cancer will lead to a more rational use of available and future therapies, with significant improvements in outcomes for our patients.

Current approaches to incorporation of radium-223 in clinical practice

Background

Treatment options for metastatic castration-resistant prostate cancer (mCRPC) have expanded in recent years and include cytotoxic agents (e.g., docetaxel and cabazitaxel), immunotherapy (e.g., sipuleucel-T), oral hormonal therapies targeting the androgen receptor axis (e.g., enzalutamide and abiraterone), and targeted alpha therapy (e.g., radium-223 dichloride (radium-223)). Although treatment guidelines have been updated to reflect the availability of new agents, it is not easy to apply them in daily clinical practice because recommendations vary depending on patient comorbidities and disease characteristics. Furthermore, therapeutic accessibility, clinical judgment, and experience affect the selection of treatment options.

Methods

In this review, we provide practical guidance for the integration of radium-223 into the management of patients with mCRPC based on our collective clinical experience, as well as the available clinical trial data.

Results

Radium-223 is a targeted alpha therapy; as a bone-seeking calcium mimetic, it accumulates in hydroxyapatite areas surrounding tumor lesions and selectively binds to the areas of increased bone turnover. Radium-223 prolongs overall survival and delays time to the first symptomatic skeletal events in men with mCRPC, and is indicated for the treatment of patients with CRPC, symptomatic bone metastases, and no known visceral metastases. We review its clinical efficacy and safety, practical guidance on identifying the appropriate patient, and recommendations for how best to educate and inform prospective patients regarding their treatment decision making. In addition, we review recent evidence for sequential and combination therapies with radium-223, provide our experiences with these treatment approaches, and discuss their implications for the future treatment of patients with mCRPC.

Conclusions

Based on our clinical experience, radium-223 should be considered relatively early in the treatment course in patients with mCRPC with bone metastases. Coordination of care among multidisciplinary team members, patients, and caregivers is essential for optimizing safe and effective treatment with all CRPC therapies.

Loco-regional treatment for castration-resistant prostate cancer: Is there any rationale? A critical review from the AFU-GETUG

Emerging evidence from population-based and retrospective series suggests a potential improvement of clinical outcomes in metastatic prostate cancer. Moreover, metastasis-directed treatment has shown encouraging results in this setting. There is an increasing interest in exploring the potential of local therapies in advanced prostate cancer, but this has rarely been specifically addressed in the castration-resistant state, whether non-metastatic or metastatic. A review of relevant articles was performed on the oncologic benefit of local treatment of the primary tumor or metastasis-targeted treatment in castration-resistant prostate cancer patients. The main goal of this strategy is to delay introduction of a new systemic agent to maintain quality of life and potentially to limit resistance. Further investigation is required to provide high-level evidence for the oncologic benefit of this treatment modality.

Sipuleucel-T for the treatment of prostate cancer: novel insights and future directions

Sipuleucel-T, an autologous cellular immunotherapy manufactured from antigen-presenting cells primed to recognize prostatic acid phosphatase, was the first immunotherapy product approved by the US FDA. It was approved for men with asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer after it was shown to provide a survival advantage. Additional studies have examined its use in other clinical settings and in combination with other approved and investigational immunotherapy agents. This review will discuss the pivotal trials leading to approval, will outline some of the biomarkers associated with its efficacy and will review some of the ongoing combination strategies. Maximizing the efficacy of sipuleucel-T through better patient selection or through combination approaches remains the challenge of the future.

ABCB1 Mediates Cabazitaxel-Docetaxel Cross-Resistance in Advanced Prostate Cancer

Advancements in research have added several new therapies for castration-resistant prostate cancer (CRPC), greatly augmenting our ability to treat patients. However, CRPC remains an incurable disease due to the development of therapeutic resistance and the existence of cross-resistance between available therapies. Understanding the interplay between different treatments will lead to improved sequencing and the creation of combinations that overcome resistance and prolong survival. Whether there exists cross-resistance between docetaxel and the next-generation taxane cabazitaxel is poorly understood. In this study, we use C4-2B and DU145 derived docetaxel-resistant cell lines to test response to cabazitaxel. Our results demonstrate that docetaxel resistance confers cross-resistance to cabazitaxel. We show that increased ABCB1 expression is responsible for cross-resistance to cabazitaxel and that inhibition of ABCB1 function through the small-molecule inhibitor elacridar resensitizes taxane-resistant cells to treatment. In addition, the antiandrogens bicalutamide and enzalutamide, previously demonstrated to be able to resensitize taxane-resistant cells to docetaxel through inhibition of ABCB1 ATPase activity, are also able to resensitize resistant cells to cabazitaxel treatment. Finally, we show that resensitization using an antiandrogen is far more effective in combination with cabazitaxel than docetaxel. Collectively, these results address key concerns in the field, including that of cross-resistance between taxanes and highlighting a mechanism of cabazitaxel resistance involving ABCB1. Furthermore, these preclinical studies suggest the potential in using combinations of antiandrogens with cabazitaxel for increased effect in treating advanced CRPC. Mol Cancer Ther; 16(10); 2257-66. ©2017 AACR.

Prognostic and predictive biomarkers in prostate cancer: latest evidence and clinical implications

Advances in our understanding of the mechanisms driving castration-resistant prostate cancer have promoted the development of several new drugs including androgen receptor-directed therapy and chemotherapy. Concomitant docetaxel treatment at the beginning of hormonal therapy for metastatic prostate cancer has resulted in longer overall survival than with hormonal therapy alone. Elucidating an appropriate treatment sequence using these therapies is important for maximizing clinical benefit in castration-sensitive and castration-resistant prostate cancer patients. The development of advanced high-throughput ‘omics’ technology has enabled the use of novel markers to guide prognosis and treatment of this disease. In this review, we outline the genomic landscape of prostate cancer and the molecular mechanisms of castration-resistant progression, and how these affect the development of new drugs, and their clinical implications for selecting treatment sequence. We also discuss many of the potential tissue-based or liquid biomarkers that may soon enter clinical use, with the hope that several of these prognostic or predictive markers will guide precision medicine for prostate cancer patients in the near future.