Overcoming persistent dependency on androgen signaling after progression to castration-resistant prostate cancer

[Therapy sequences and duration in mCRPC: a retrospective review of the Lübeck mCRPC cohort]

BACKGROUND

Prostate cancer is one of the most common cancers in men in Europe. Several classes of agents can be considered for the treatment of metastatic prostate carcinoma, and their use is supported by extensive guidelines. In the treatment of metastatic castration-resistant prostate cancer (mCRPC), it is currently unclear which sequence of systemic therapies is most effective. Currently approved system therapies in the castration-resistant setting generally include hormone-manipulating agents, taxane-based chemotherapies, radioactive agents, or inhibitiors of DNA repair mechanisms. This study aims to summarize real world data of mCRPC therapy.

METHODS

Retrospectively, 90 mCRPC patients undergoing treatment at the University Hospital Schleswig-Holstein, Lübeck Campus between February 2006 and March 2020 were identified. The patient data were analyzed for their treatment sequence and disease progression. Due to the inclusion period, the mCRPC therapy sequences studied were limited to: Abiraterone, Cabazitaxel, Docetaxel, Enzalutamide, Lutetium-177-PSMA and Radium-223. The analysis includes the therapy sequences and their duration, clinical information of the respective cohort, overall and cancer-specific survival (OS/CSS) as well as time to second-line therapy in relation to the respective first-line therapy.

RESULTS

Approximately two-thirds of patients underwent a true therapy sequence (at least two of the drugs listed above), with this proportion halving by the third line.The majority of patients received the sequence (first/second line) abiraterone/docetaxel (n=13), followed by docetaxel/abiraterone (n=12) and abiraterone/enzalutamid (n=10) and docetaxel/docetaxel (n=8).Within the different docetaxel sequences, first-line (mean 4.7 months ± SD 3.1; median 4.0) and rechallenge (mean 5.3 months ± SD 5.9; median 3.0) therapy durations were the longest. The subjective side effect rate of docetaxel was lower in the second line, so that a better tolerability can be assumed here.The abiraterone/docetaxel sequence was used mainly in patients with metachronous metastases. Among the different sequences of abiraterone, first-line (mean 10.8 months ± SD 10.2; median 9.0) and second-line (mean 10.6 months ± SD 9.0; median 7.0) therapy durations were the longest.The sequence abiraterone/enzalutamide was prescribed mainly to older patients with synchronous metastases. Among the different enzalutamide sequences first-line (mean 9.6 months ± SD 7.1; median 7.0) and rechallenge (mean 11.0 ± SD 0.0; median 11.0) therapy durations were the longest.In contrast, the sequence docetaxel/docetaxel was used mainly in younger patients with a high initial PSA.The evaluation shows a trend that both abiraterone and enzalutamide can account for a survival advantage in the first line.

CONCLUSION

Ultimately, an optimal treatment sequence cannot be confidently derived from these data.However, it was found that only a small proportion of patients underwent fourth- or even fifth-line treatment at all. Thus, the focus on first- and second-line in this study seems reasonable. It could be shown in a trend that docetaxel as first-line therapy seems to be disadvantegous regarding OS as well as CSS when compared to abiraterone or enzalutamide. However, due to the small number of patients in this study, a clear significance cannot be derived. Moreover, the subjectively better tolerability of docetaxel in the second-line setting could provide an impetus for treatment planning in multimorbid elderly patients in the future. The sequence abiraterone/docetaxel may offer a beneficial option for initial mCRPC therapy.

Discovery of novel biphenyl derivatives as androgen receptor degraders for the treatment of enzalutamide-resistant prostate cancer

Second-generation AR antagonists, such as enzalutamide, are the primary therapeutic agents for advanced prostate cancer. However, the development of both primary and secondary drug resistance leads to treatment failures and patient mortality. Bifunctional agents that simultaneously antagonize and degrade AR block the AR signaling pathway more completely and exhibit excellent antiproliferative activity against wild-type and drug-resistant prostate cancer cells. Here, we reported the discovery and optimization of a series of biphenyl derivatives as androgen receptor antagonists and degraders. These biphenyl derivatives exhibited potent antiproliferative activity against LNCaP and 22Rv1 cells. Our discoveries enrich the diversity of small molecule AR degraders and offer insights for the development of novel AR degraders for the treatment of enzalutamide-resistant prostate cancer.

Structure-Activity Relationship (SAR) Studies of Novel Monovalent AR/AR-V7 Dual Degraders with Potent Efficacy against Advanced Prostate Cancer

Androgen receptor (AR) has been extensively established as a potential therapeutic target for nearly all stages of prostate cancer (PCa). However, acquired resistance to AR-targeted drugs inevitably develops and severely limits their clinical efficacy. Particularly, there currently exists no efficient treatment for patients expressing the constitutively active AR splice variants, such as AR-V7. Herein, we report the structure-activity relationship studies of 55 N-heterocycle-substituted hydantoins, which identified the structural motifs required for AR/AR-V7 degradation. Among them, the most potent compound 27c exhibited selective AR/AR-V7 degradation over other hormone receptors and excellent antiproliferative activities in LNCaP and 22RV1 cells. RNA sequence analysis confirmed that 27c effectively suppressed transcriptional activity of the AR signaling pathway. Importantly, 27c demonstrated potent antitumor efficacy in an enzalutamide-resistant 22RV1 xenograft model. These results highlight the potential of 27c as a promising dual AR/AR-V7 degrader for overcoming drug resistance in advanced PCa expressing AR splice variants.

Combination of docetaxel versus nonsteroidal antiandrogen with androgen deprivation therapy for high-volume metastatic hormone-sensitive prostate cancer: a propensity score-matched analysis

PURPOSE

The aim of this study was to investigate the oncologic efficacy of combining docetaxel with androgen deprivation therapy (ADT) versus nonsteroidal antiandrogen (NSAA) with ADT in patients with high-volume metastatic hormone-sensitive prostate cancer (mHSPC) with focus on the effect of sequential therapy in a real-world clinical practice setting.

METHODS

The records of 382 patients who harbored high-volume mHSPC, based on the CHAARTED criteria, and had received ADT with either docetaxel (n = 92) or NSAA (bicalutamide) (n = 290) were retrospectively analyzed. The cohorts were matched by one-to-one propensity scores based on patient demographics. Overall survival (OS), cancer-specific survival (CSS), progression-free survival (PFS), including time to castration-resistant prostate cancer (CRPC), and time to second-line progression (PFS2) were compared. 2nd-line PFS defined as the time from CRPC diagnosis to progression after second-line therapy was also compared.

RESULTS

After matching, a total of 170 patients were retained: 85 patients treated with docetaxel + ADT and 85 patients treated with NSAA + ADT. The median OS and CSS for docetaxel + ADT versus NSAA + ADT were not reached (NR) vs. 49 months (p = 0.02) and NR vs. 55 months (p = 0.02), respectively. Median time to CRPC and PFS2 in patients treated with docetaxel + ADT was significantly longer compared to those treated with NSAA (22 vs. 12 months; p = 0.003 and, NR vs. 28 months; p < 0.001, respectively). There was no significant difference in 2nd-line PFS between the two groups.

CONCLUSIONS

Our analysis suggested that ADT with docetaxel significantly prolonged OS and CSS owing to a better time to CRPC and PFS2 in comparison to NSAA + ADT in high-volume mHSPC.

Discovery of a Novel Bifunctional Steroid Analog, YXG-158, as an Androgen Receptor Degrader and CYP17A1 Inhibitor for the Treatment of Enzalutamide-Resistant Prostate Cancer

The androgen/androgen receptor (AR) signaling pathway plays an important role in castration-resistant prostate cancer (CRPC). Bifunctional agents that simultaneously degrade AR and inhibit androgen synthesis are expected to block the androgen/AR signaling pathway more thoroughly, demonstrating the promising therapeutic potential for CRPC, even enzalutamide-resistant CRPC. Herein, a series of steroid analogs were designed, synthesized, and identified as selective AR degraders, among which YXG-158 (23-h) was the most potent antitumor compound with dual functions of AR degradation and CYP17A1 inhibition. In addition, 23-h abrogated the hERG inhibition and exhibited excellent PK profiles. In vivo, 23-h effectively inhibited the growth of hormone-sensitive organs in the Hershberger assay and exhibited robust antitumor efficacy both in enzalutamide-sensitive (LNCaP/AR) and enzalutamide-resistant (C4-2b-ENZ) xenograft models. Thus, 23-h was chosen as a preclinical candidate for the treatment of enzalutamide-resistant prostate cancer.

Discovery of thiohydantoin based antagonists of androgen receptor with efficient degradation for the treatment of prostate cancer

Prostate cancer (PC) is one of the most prevalent cancers in men worldwide, and androgen receptor (AR) is a well-validated drug target for the treatment of PC. However, PC often exhibits resistance to AR antagonists over time. Thus, it is urgent to identify novel and effective drugs for PC treatment. A series of novel thiohydantoin based AR antagonists with efficient degradation against AR were designed, synthesized, and evaluated. Based on our previous SAR and further structural optimization, a tool molecule 26h was discovered with dual mechanisms including improved antagonistic activity and potent degradation (AR-fl and AR-V7). Moreover, 26h can also effectively block AR nuclear translocation and inhibit AR/AR-V7 heterodimerization, thereby inhibiting downstream gene transcription. Importantly, 26h displayed potent robust efficacy in LNCaP (TGI: 70.70%) and 22Rv1 (TGI: 78.89%) xenograft models. This provides new design strategies and advantageous potential compounds for the treatment of prostate cancer.

Predictive factors for the effectiveness of novel androgen receptor axis-targeted agents in patients with metastatic prostate cancer

OBJECTIVE

Novel androgen receptor axis-targeted agents (ARATAs) have been developed for mCRPC and improved overall survival (OS). Here, we aimed to find predictors who will receive the greatest benefits from ARATAs.

METHODS

We previously performed a multicenter study to identify prognostic factors for metastatic hormone-sensitive prostate cancer (mHSPC, n = 148) and mCRPC (n = 99), and showed that the bone scan index (BSI) was one of the significant prognostic factors for 3-year OS (PROSTAT-BSI study). mHSPC progressed to mCRPC (n = 101), for which 69 patients were treated with (n = 39) or without ARATAs (n = 30, prior to the approval of ARATAs). The 69 patients were divided into two groups according to patient factors, and these cohorts were further divided into two subgroups by usage of ARATAs. OS was compared between subgroups in each group.

RESULTS

The predictors were age (<71.4 years), serum levels of C-reactive protein (≥0.16 ng/ml) and alkaline phosphatase (≥548 U/L), time to PSA progression after ADT (<8.9 months), the lowest PSA level (≥1 ng/ml) after ADT, and the rate of PSA decline 3 months after ADT (<0.987), whereas hemoglobin levels, PSA before ADT, Gleason scores, existence of visceral metastases, and BSI were not.

CONCLUSIONS

The present study identified predictors for the effectiveness of ARATAs. The number of bone metastases (≒BSI), existence of visceral metastases, and Gleason scores, which were identified as high-risk factors in the LATITUDE study and disease volume in CHAARTED criteria, did not appear to be useful for predicting effectiveness from ARATAs.

Efficacy and safety of therapies for advanced prostate cancer in Asia: Evidence from a systematic literature review

OBJECTIVES

Several therapies are available for the treatment of advanced/metastatic prostate cancer (PC). However, the systematic assessment of evidence pertaining to the use of these therapies in Asian patients is lacking.

METHODS

A systematic literature review (SLR) was conducted using PubMed/Medline search in May 2021 to identify the randomized/nonrandomized controlled trials (RCTs/non-RCTs) and real-world observational studies (prospective/retrospective). Only studies published as full manuscripts in English were included if reporting the efficacy, effectiveness, and/or safety of treatments in Asian patients with advanced/metastatic PC.

RESULTS

Of the 1,898 retrieved publications, 24 studies were included. These studies had patients with nonmetastatic castration-resistant PC (n = 2), metastatic castration-sensitive PC (n = 4), and metastatic castration-resistant PC (n = 18). Study designs included RCTs (n = 7), non-RCTs (n = 2), and real-world studies (n = 15). Treatments used in included studies were abiraterone acetate plus prednisone (AAP; n = 6), enzalutamide, lutetium-177 prostate-specific membrane antigen (177Lu-PSMA; n = 4 each), docetaxel (n = 3), apalutamide, radium-223 (n = 2 each), darolutamide, cabazitaxel, and pembrolizumab (n = 1 each). The evidence from RCTs (i.e., ARAMIS, SPARTAN, ARCHES, TITAN, LATITUDE, PREVAIL) demonstrated the clinical benefits of apalutamide, darolutamide, enzalutamide, and AAP in terms of overall, disease-free, and metastasis-free survival in Asian patients. These treatments were reported to be well tolerated, with no new safety signals identified in Asian population. The efficacy and safety profiles in Asian patients were consistent with the overall trial population. Data from real-world studies supported the effectiveness and tolerability of AAP, enzalutamide, radium-223, docetaxel, cabazitaxel, 177Lu-PSMA, and pembrolizumab in patients with advanced/metastatic PC.

CONCLUSIONS

This SLR of the Asian data on therapies for advanced PC from the pivotal and real-world studies confirms similar efficacy and safety outcomes, consistent with the results from the pivotal clinical trials. These findings will help clinicians make better treatment decisions in clinical practice for patients with advanced/metastatic PC.

Design, Synthesis, and Biological Evaluation of Androgen Receptor Degrading and Antagonizing Bifunctional Steroidal Analogs for the Treatment of Advanced Prostate Cancer

Metastatic castration-resistant prostate cancer (mCRPC) with high mortality has seriously threatened men's health. Bifunctional agents simultaneously degrade and antagonize androgen receptor (AR), display robust AR signaling pathway blockade, and show the therapeutic prospect for mCRPC. Herein, systemic structural modifications on the C-3, C-6, and C-17 positions of galeterone led to the discovery of 67-b with the dual functions of AR antagonism and degradation. In vitro, 67-b exhibited excellent antiproliferative activity and potent AR degradation activity in different PCa cells (LNCaP and 22RV1), as well as outstanding antagonistic activity against wild-type and mutant (W741L, T877A, and F876L) ARs. In vivo, 67-b effectively inhibited the growth of hormone-sensitive organs in the Hershberger assay and exhibited tumor regression in the enzalutamide-resistant (c4-2b-ENZ) xenograft model. These results confirmed 67-b to be a promising AR degrader and antagonist for the treatment of mCRPC patients.

Positive epigenetic regulation loop between AR and NSUN2 promotes prostate cancer progression

BACKGROUND

Prostate cancer (PCa) is a major type of cancer in man worldwide. Androgen deprivation therapy (ADT) and the next-generation androgen receptor (AR) pathway inhibitors have acquired great success in treating PCa. However, patients treated with ADT or AR targeted therapy are inevitably developing into castration-resistant prostate cancer (CRPC) or becoming drug resistance. The role of mRNA 5-methylcytosine (m5C) modification in cancers is largely unknown. This study aimed to explore the role of the m5C methyltransferase NSUN2 in Prostate cancer (PCa).

METHODS

The expression of NSUN2 and its clinicopathological impact were evaluated in PCa cohorts. The effect of NSUN2 on the biological characteristics of PCa cells was investigated on the basis of gain-offunction and loss-of-function analyses. Subcutaneous models further uncovered the role of NSUN2 in tumor growth. Epi-transcriptome assays with RNA bisulfite sequencing (RNA-BisSeq) analysis and in vitro enzyme reaction assays were performed to validate the targeted effect of NSUN2 on AR. AR-binding sites in the NSUN2 promoter were investigated by ChIP and luciferase assays to uncover the interplay between NSUN2 and AR signaling. RIP-qPCR and EMSA methods were performed to confirm that YBX1 binds to AR m5 C sites.

RESULTS

NSUN2 is highly expressed in PCa and predicts poor outcome. NSUN2 plays roles as a PCa oncogene both in vitro and in vivo. Depletion of NSUN2 results in decreased expression and activities of AR, including AR-V7. Mechanistically, NSUN2 posttranscriptionally stabilized AR by cluster m5 C modification in a m5CYBX1-dependent manner. Strikingly, treatment with enzalutamide, an effective AR inhibitor, reduces NSUN2 expression and decreases the m5C modification level in prostate cancer cells. Finally, we found that AR transcriptionally regulates NSUN2.

CONCLUSION

NSUN2 stabilizes AR mRNA through cluster 5-methylcytosine modification and activates a positive feedback loop to promote prostate cancer.

The Discovery of BMS-737 as a Potent, CYP17 Lyase-Selective Inhibitor for the Treatment of Castration-Resistant Prostate Cancer

We report herein, the discovery of BMS-737 (compound 33) as a potent, non-steroidal, reversible small molecule inhibitor demonstrating 11-fold selectivity for CYP17 lyase over CYP17 hydroxylase, as well as a clean xenobiotic CYP profile for the treatment of castration-resistant prostate cancer (CRPC). Extensive SAR studies on the initial lead 1 at three different regions of the molecule resulted in the identification of BMS-737, which demonstrated a robust 83% lowering of testosterone without any significant perturbation of the mineralocorticoid and glucocorticoid levels in cynomologous monkeys in a 1-day PK/PD study.

Abiraterone acetate versus nonsteroidal antiandrogen with androgen deprivation therapy for high-risk metastatic hormone-sensitive prostate cancer

BACKGROUND

Although prostate cancer is a very common form of malignancy in men, the clinical significance of androgen deprivation therapy (ADT) with abiraterone acetate versus the nonsteroidal antiandrogen bicalutamide has not yet been verified in patients with high-risk metastatic hormone-sensitive prostate cancer (mHSPC). The present study was designed to initiate this verification in real-world Japanese clinical practice.

METHODS

We retrospectively analyzed the records of 312 patients with high-risk mHSPC based on LATITUDE criteria and had received ADT with bicalutamide (n = 212) or abiraterone acetate (n = 100) between September 2015 and December 2020. Bicalutamide was given at 80 mg daily and abiraterone was given at 1000 mg daily as four 250-mg tablets plus prednisolone (5-10 mg daily). Overall survival (OS), cancer-specific survival (CSS), and time to castration-resistant prostate cancer (CRPC) were compared. The prognostic factor for time to CRPC was analyzed by Cox proportional hazard model.

RESULTS

Patients in the bicalutamide group were older, and more of them had poor performance status (≧2), than in the abiraterone group. Impaired liver function was noted in 2% of the bicalutamide group and 16% of the abiraterone group (p < 0.001). Median follow-up was 22.5 months for bicalutamide and 17 months for abiraterone (p < 0.001). Two-year OS and CSS for bicalutamide versus abiraterone was 77.8% versus 79.5% (p = 0.793) and 81.1% versus 82.5% (p = 0.698), respectively. Median time to CRPC was significantly longer in the abiraterone group than in the bicalutamide group (NA vs. 13 months, p < 0.001). In multivariate analysis, Gleason score ≧9, high alkaline phosphatase, high lactate dehydrogenase, liver metastasis, and bicalutamide were independent prognostic risk factors for time to CRPC. Abiraterone prolonged the time to CRPC in patients with each of these prognostic factors.

CONCLUSIONS

Despite limitations regarding the time-dependent bias, ADT with abiraterone acetate significantly prolonged the time to CRPC compared to bicalutamide in patients with high-risk mHSPC. However, further study with longer follow-up is needed.

Apalutamide plus abiraterone acetate and prednisone versus placebo plus abiraterone and prednisone in metastatic, castration-resistant prostate cancer (ACIS): a randomised, placebo-controlled, double-blind, multinational, phase 3 study

BACKGROUND

The majority of patients with metastatic castration-resistant prostate cancer (mCRPC) will have disease progression of a uniformly fatal disease. mCRPC is driven by both activated androgen receptors and elevated intratumoural androgens; however, the current standard of care is therapy that targets a single androgen signalling mechanism. We aimed to investigate the combination treatment using apalutamide plus abiraterone acetate, each of which suppresses the androgen signalling axis in a different way, versus standard care in mCRPC.

METHODS

ACIS was a randomised, placebo-controlled, double-blind, phase 3 study done at 167 hospitals in 17 countries in the USA, Canada, Mexico, Europe, the Asia-Pacific region, Africa, and South America. We included chemotherapy-naive men (aged ≥18 years) with mCRPC who had not been previously treated with androgen biosynthesis signalling inhibitors and were receiving ongoing androgen deprivation therapy, with an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, and a Brief Pain Inventory-Short Form question 3 (ie, worst pain in the past 24 h) score of 3 or lower. Patients were randomly assigned (1:1) via a centralised interactive web response system with a permuted block randomisation scheme (block size 4) to oral apalutamide 240 mg once daily plus oral abiraterone acetate 1000 mg once daily and oral prednisone 5 mg twice daily (apalutamide plus abiraterone-prednisone group) or placebo plus abiraterone acetate and prednisone (abiraterone-prednisone group), in 28-day treatment cycles. Randomisation was stratified by presence or absence of visceral metastases, ECOG performance status, and geographical region. Patients, the investigators, study team, and the sponsor were masked to group assignments. An independent data-monitoring committee continually monitored data to ensure ongoing patient safety, and reviewed efficacy data. The primary endpoint was radiographic progression-free survival assessed in the intention-to-treat population. Safety was reported for all patients who received at least one dose of study drug. This study is completed and no longer recruiting and is registered with ClinicalTrials.gov, number NCT02257736.

FINDINGS

982 men were enrolled and randomly assigned from Dec 10, 2014 to Aug 30, 2016 (492 to apalutamide plus abiraterone-prednisone; 490 to abiraterone-prednisone). At the primary analysis (median follow-up 25·7 months [IQR 23·0-28·9]), median radiographic progression-free survival was 22·6 months (95% CI 19·4-27·4) in the apalutamide plus abiraterone-prednisone group versus 16·6 months (13·9-19·3) in the abiraterone-prednisone group (hazard ratio [HR] 0·69, 95% CI 0·58-0·83; p<0·0001). At the updated analysis (final analysis for overall survival; median follow-up 54·8 months [IQR 51·5-58·4]), median radiographic progression-free survival was 24·0 months (95% CI 19·7-27·5) versus 16·6 months (13·9-19·3; HR 0·70, 95% CI 0·60-0·83; p<0·0001). The most common grade 3-4 treatment-emergent adverse event was hypertension (82 [17%] of 490 patients receiving apalutamide plus abiraterone-prednisone and 49 [10%] of 489 receiving abiraterone-prednisone). Serious treatment-emergent adverse events occurred in 195 (40%) patients receiving apalutamide plus abiraterone-prednisone and 181 (37%) patients receiving abiraterone-prednisone. Drug-related treatment-emergent adverse events with fatal outcomes occurred in three (1%) patients in the apalutamide plus abiraterone-prednisone group (2 pulmonary embolism, 1 cardiac failure) and five (1%) patients in the abiraterone-prednisone group (1 cardiac failure and 1 cardiac arrest, 1 mesenteric arterial occlusion, 1 seizure, and 1 sudden death).

INTERPRETATION

Despite the use of an active and established therapy as the comparator, apalutamide plus abiraterone-prednisone improved radiographic progression-free survival. Additional studies to identify subgroups of patients who might benefit the most from combination therapy are needed to further refine the treatment of mCRPC.

FUNDING

Janssen Research & Development.

Exploration and Biological Evaluation of Basic Heteromonocyclic Propanamide Derivatives as SARDs for the Treatment of Enzalutamide-Resistant Prostate Cancer

A series of propanamide derivatives were designed, synthesized, and pharmacologically characterized as selective androgen receptor degraders (SARDs) and pan-antagonists that exert a broad-scope androgen receptor (AR) antagonism. Incorporating different basic heteromonocyclic B-ring structural elements in the common A-ring-linkage-B-ring nonsteroidal antiandrogen general pharmacophore contributed to a novel scaffold of small molecules with SARD and pan-antagonist activities even compared to our recently published AF-1 binding SARDs such as UT-69 (11), UT-155 (12), and UT-34 (13). Compound 26f exhibited inhibitory and degradation effects in vitro in a wide array of wtAR, point mutant, and truncation mutant-driven prostate cancers (PCs). Further, 26f inhibited tumor cell growth in a xenograft model composed of enzalutamide-resistant (EnzR) LNCaP cells. These results demonstrate an advancement toward the development of novel SARDs and pan-antagonists with efficacy against EnzR prostate cancers.

Long-term outcomes of androgen deprivation therapy in prostate cancer among Japanese men over 80 years old

This study aimed to analyze the survival rate and to examine the risk of death from prostate cancer when accounting for competing risk of death, in men aged ≥80 y treated with primary androgen deprivation therapy (ADT). Data of patients with prostate cancer who had received ADT were extracted from a nationwide community‐based database established by the Japan Study Group for Prostate Cancer. Prognostic variables, including progression‐free survival, cancer‐specific survival, overall survival, and death rates were compared between men stratified by prostate cancer risk. Overall, 4760 patients older than 80 y were included. The proportion of low‐, intermediate‐, high‐, or very high‐risk, regional, and metastatic prostate cancer among super‐elderly men was 9.5%, 14.6%, 48.8%, 9.0%, 3.2%, and 24.9%, respectively. Survival rates decreased with increasing risk stratification. The cumulative 5‐y death rate by prostate cancer for low‐, intermediate‐, high‐, or very high‐risk, regional, and metastatic prostate cancer, was 0.92% (95% confidence interval [CI]: 0.2%‐3.6%), 1.6% (95% CI: 0.8%‐3.4%), 5.75% (95% CI: 4.25%‐7.75%), 15.6% (95% CI: 11.6%‐23.3%), 20.7% (95% CI: 13.1%‐31.7%), and 36.9% (95% CI: 32.8%‐41.4%), respectively. Our findings support that there is no need for immediate ADT for low‐ and intermediate‐risk groups. Conversely, in high‐ or very high‐risk, regional, and metastatic prostate cancer, more efforts for curative therapy and intensive therapy are needed in selected patients.

Apalutamide for metastatic, castration-sensitive prostate cancer in the Japanese population: A subgroup analysis of the randomized, double-blind, placebo-controlled phase 3 TITAN study

OBJECTIVE

To evaluate the efficacy and safety of apalutamide + androgen deprivation therapy versus androgen deprivation therapy alone in Japanese patients with metastatic castration-sensitive prostate cancer from the phase 3, randomized, global TITAN study.

METHODS

Men with metastatic castration-sensitive prostate cancer randomly (1:1) received 240 mg apalutamide + androgen deprivation therapy or matching placebo + androgen deprivation therapy. The primary efficacy endpoints were radiographic progression-free survival and overall survival. Secondary efficacy endpoints were time to cytotoxic chemotherapy, pain progression, chronic opioid use, and skeletal-related events. Safety was also assessed.

RESULTS

Of the 1052 patients included in the TITAN study, 51 (4.85%) were Japanese (apalutamide group, n = 28; placebo group, n = 23). In all, 81.8% of patients in the apalutamide and 71.8% in the placebo group did not experience radiographic progression or death, and the hazard ratio for radiographic progression-free survival favored treatment with apalutamide (hazard ratio 0.712, 95% confidence interval 0.205-2.466; P = 0.59). At 24 months, 85.7% of patients in the apalutamide group and 81.5% in the placebo group were alive, and the hazard ratio for overall survival favored apalutamide (hazard ratio 0.840, 95% confidence interval 0.210-3.361; P = 0.805). In the interim analysis, the median radiographic progression-free survival and overall survival were not reached in the apalutamide group and time to cytotoxic chemotherapy was delayed following apalutamide treatment. The safety profile of apalutamide in the Japanese subpopulation was comparable with that of the global population, except for skin rash.

CONCLUSIONS

The results of the present analyses suggest that apalutamide + androgen deprivation therapy in Japanese patients had favorable efficacy compared with androgen deprivation therapy alone, and these findings are comparable to those in the overall population. Apalutamide + androgen deprivation therapy can be considered as one of the therapeutic options for a broad spectrum of metastatic castration-sensitive prostate cancer regardless of prior treatment and disease extent in Japanese patients.

Pyrazol-1-yl-propanamides as SARD and Pan-Antagonists for the Treatment of Enzalutamide-Resistant Prostate Cancer

We report herein the design, synthesis, and pharmacological characterization of a library of novel aryl pyrazol-1-yl-propanamides as selective androgen receptor degraders (SARDs) and pan-antagonists that exert broad-scope AR antagonism. Pharmacological evaluation demonstrated that introducing a pyrazole moiety as the B-ring structural element in the common A-ring-linkage-B-ring nonsteroidal antiandrogens' general pharmacophore allowed the development of a new scaffold of small molecules with unique SARD and pan-antagonist activities even compared to our recently published AF-1 binding SARDs such as UT-155 (9) and UT-34 (10). Novel B-ring pyrazoles exhibited potent AR antagonist activities, including promising distribution, metabolism, and pharmacokinetic properties, and broad-spectrum AR antagonist properties, including potent in vivo antitumor activity. 26a was able to induce an 80% tumor growth inhibition of xenografts derived from the enzalutamide-resistant (Enz-R) VCaP cell line. These results represent an advancement toward the development of novel AR antagonists for the treatment of Enz-R prostate cancer.

Anticancer Imidazoacridinone C-1311 is Effective in Androgen-Dependent and Androgen-Independent Prostate Cancer Cells

The androgen receptor (AR) plays a critical role in prostate cancer (PCa) development and metastasis. Thus, blocking AR activity and its downstream signaling constitutes a major strategy for PCa treatment. Here, we report on the potent anti-PCa activity of a small-molecule imidazoacridinone, C-1311. In AR-positive PCa cells, C-1311 was found to inhibit the transcriptional activity of AR, uncovering a novel mechanism that may be relevant for its anticancer effect. Mechanistically, C-1311 decreased the AR binding to the prostate-specific antigen (PSA) promoter, reduced the PSA protein level, and, as shown by transcriptome sequencing, downregulated numerous AR target genes. Importantly, AR-negative PCa cells were also sensitive to C-1311, suggesting a promising efficacy in the androgen-independent PCa sub-type. Irrespective of AR status, C-1311 induced DNA damage, arrested cell cycle progression, and induced apoptosis. RNA sequencing indicated significant differences in the transcriptional response to C-1311 between the PCa cells. Gene ontology analysis showed that in AR-dependent PCa cells, C-1311 mainly affected the DNA damage response pathways. In contrast, in AR-independent PCa cells, C-1311 targeted the cellular metabolism and inhibited the genes regulating glycolysis and gluconeogenesis. Together, these results indicate that C-1311 warrants further development for the treatment of PCa.

Efficacy and safety of apalutamide in Japanese patients with nonmetastatic castration-resistant prostate cancer: a subgroup analysis of a randomized, double-blind, placebo-controlled, Phase-3 study

Background

In the global Phase-3 Selective Prostate Androgen Receptor Targeting with ARN-509 study, apalutamide plus ongoing androgen deprivation therapy (ADT) significantly increased metastasis-free survival (MFS) and improved other clinical outcomes in men with nonmetastatic castration-resistant prostate cancer (nm-CRPC) who were at high risk of developing metastases. In this subpopulation analysis of Selective Prostate Androgen Receptor Targeting with ARN-509 study, the efficacy and safety of apalutamide plus ADT were evaluated in Japanese patients with nm-CRPC.

Methods

The primary efficacy end point was MFS. Secondary efficacy end points were time to metastasis, progression-free survival, symptomatic progression, initiation of cytotoxic chemotherapy, and overall survival. Safety and pharmacokinetic parameters were also assessed.

Results

Fifty-five Japanese patients with ongoing ADT were randomized (apalutamide: n = 34, placebo: n = 21). Median treatment duration was 5.7 months in the apalutamide group and 11.0 months in the placebo group. Median MFS was not reached in the apalutamide group (95% confidence interval: 10.97, not estimable) and was 18.23 months (95% confidence interval: 11.04, 18.50) in the placebo group. Secondary end points were improved in the apalutamide group. The safety profile of apalutamide with ADT was comparable with the global population, and no new safety signals were identified in this Japanese subpopulation. Although, apalutamide exposure tended to be higher in the Japanese subpopulation compared with the non-Japanese population, this was likely to be explained by body weight and considered not clinically meaningful.

Conclusion

In the Japanese subpopulation, treatment with apalutamide with ADT resulted in favorable efficacy outcomes with comparable benefit-risk profile to the global population with nm-CRPC who are at high-risk of developing metastases.

Androgen deprivation therapy with chemotherapy or abiraterone for patients with metastatic hormone-naive prostate cancer: a systematic review and meta-analysis

Patients with metastasis prostate cancer underwent androgen deprivation therapy (ADT) in the considering of the leading role of androgen receptor pathway. However, the resistance occurred within 1 year or more. The combination of cytotoxic chemotherapy and abiraterone for ADT therapy was performed in recent randomized controlled trials. The meta-analysis was focused on the treatment comparisons between additional treatment with ADT and ADT alone. A significant difference was observed that the overall survival benefit of early and active additional treatment with ADT in patients with hormone-sensitive metastatic prostate cancer. However, a great proportion of patients with metastatic disease have metastases after receiving ADT. It will be important to further improve the treatment options.

Suppressive Role of Androgen/Androgen Receptor Signaling via Chemokines on Prostate Cancer Cells

Androgen/androgen receptor (AR) signaling is a significant driver of prostate cancer progression, therefore androgen-deprivation therapy (ADT) is often used as a standard form of treatment for advanced and metastatic prostate cancer patients. However, after several years of ADT, prostate cancer progresses to castration-resistant prostate cancer (CRPC). Androgen/AR signaling is still considered an important factor for prostate cancer cell survival following CRPC progression, while recent studies have reported dichotomic roles for androgen/AR signaling. Androgen/AR signaling increases prostate cancer cell proliferation, while simultaneously inhibiting migration. As a result, ADT can induce prostate cancer metastasis. Several C-C motif ligand (CCL)-receptor (CCR) axes are involved in cancer cell migration related to blockade of androgen/AR signaling. The CCL2-CCR2 axis is negatively regulated by androgen/AR signaling, with the CCL22-CCR4 axis acting as a further downstream mediator, both of which promote prostate cancer cell migration. Furthermore, the CCL5-CCR5 axis inhibits androgen/AR signaling as an upstream mediator. CCL4 is involved in prostate carcinogenesis through macrophage AR signaling, while the CCL21-CCR7 axis in prostate cancer cells is activated by tumor necrotic factor, which is secreted when androgen/AR signaling is inhibited. Finally, the CCL2-CCR2 axis has recently been demonstrated to be a key contributor to cabazitaxel resistance in CRPC.

Phenotypes of circulating tumour cells predict time to castration resistance in metastatic castration-sensitive prostate cancer

OBJECTIVES

To identify biomarkers that predict the response to standard androgen deprivation therapy (ADT) of patients newly diagnosed with metastatic castration-sensitive prostate cancer (CSPC) in order to improve therapeutic decision-making, and to investigate whether the characterization of baseline circulating tumour cells (CTCs) would predict the effective period of standard ADT.

MATERIALS AND METHODS

The study included 108 patients newly diagnosed with high-volume metastatic CSPC. Enumeration and characterization of patients' baseline CTCs (CTCs+ and CTCs-, indicating detectable and undetectable CTCs, respectively) were performed using the CanPatrol technique, which detects markers of the epithelial to mesenchymal transition (EMT) in CTCs, and classifies CTCs into epithelial, biophenotypic and mesenchymal phenotypes.

RESULTS

After a median follow-up of 24 months, 90 patients (83.3%) progressed to castration-resistant prostate cancer (CRPC), 93 patients (86.1%) had detectable CTCs, and the median number of CTCs was 4. The rate of progression to CRPC was significantly higher for patients with mesenchymal CTCs+ than for patients with CTCs+/mesenchymal CTCs- and CTCs- (93.1% vs 71.4% and 73.3%; P = 0.013). The median time to CRPC for patients with mesenchymal CTCs+ was significantly shorter than for those with CTCs+/mesenchymal CTCs- and CTCs- (10.5 months vs 18.0 and 14.0 months; P = 0.003). Multivariate Cox regression analysis suggested that the CTC phenotype was the only independent prognostic factor influencing the progression of disease from CSPC to CRPC.

CONCLUSIONS

Characterization of baseline CTCs according to the EMT phenotype predicted the effective period of standard ADT for patients newly diagnosed with metastatic CSPC. These findings are important for counselling patients and designing clinical trials.

Role of the androgen signaling axis in genitourinary malignancies

As we learn more about the molecular biology of genitourinary malignancies, novel therapeutic strategies can be developed. This is especially crucial for prostate, renal, and bladder cancer, where mortality rates remain high especially in advanced disease states. The androgen signaling axis and the androgen receptor (AR) are areas that are actively being explored for their role in these diseases. Although long been associated with prostate cancer development and progression, the role of AR in renal cell carcinoma (RCC) and bladder cancer is becoming recognized as well. This review will highlight the current research into the role of the androgen signaling axis in genitourinary malignancies and how this pathway is being used to expand our therapeutic armamentarium.

BRCA1 Interacting Protein COBRA1 Facilitates Adaptation to Castrate-Resistant Growth Conditions

COBRA1 (co-factor of BRCA1) is one of the four subunits of the negative elongation factor originally identified as a BRCA1-interacting protein. Here, we provide first-time evidence for the oncogenic role of COBRA1 in prostate pathogenesis. COBRA1 is aberrantly expressed in prostate tumors. It positively influences androgen receptor (AR) target gene expression and promoter activity. Depletion of COBRA1 leads to decreased cell viability, proliferation, and anchorage-independent growth in prostate cancer cell lines. Conversely, overexpression of COBRA1 significantly increases cell viability, proliferation, and anchorage-independent growth over the higher basal levels. Remarkably, AR-positive androgen dependent (LNCaP) cells overexpressing COBRA1 survive under androgen-deprivation conditions. Remarkably, treatment of prostate cancer cells with well-studied antitumorigenic agent, 2-methoxyestradiol (2-ME₂), caused significant DNA methylation changes in 3255 genes including COBRA1. Furthermore, treatment of prostate cancer cells with 2-ME₂ downregulates COBRA1 and inhibition of prostate tumors in TRAMP (transgenic adenocarcinomas of mouse prostate) animals with 2-ME₂ was also associated with decreased COBRA1 levels. These observations implicate a novel role for COBRA1 in progression to CRPC and suggest that COBRA1 downregulation has therapeutic potential.

Exploring the Interaction Mechanism Between Cyclopeptide DC3 and Androgen Receptor Using Molecular Dynamics Simulations and Free Energy Calculations

Androgen receptor (AR) is a key target in the discovery of anti-PCa (Prostate Cancer) drugs. Recently, a novel cyclopeptide Diffusa Cyclotide-3 (DC3), isolated from Hedyotisdiffusa, has been experimentally demonstrated to inhibit the survival and growth of LNCap cells, which typically express T877A-mutated AR, the most frequently detected point mutation of AR in castration-resistant prostate cancer (CRPC). But the interaction mechanism between DC3 and AR is not clear. Here in this study we aim to explore the possible binding mode of DC3 to T877A-mutated AR from molecular perspective. Firstly, homology modeling was employed to construct the three-dimensional structure of the cyclopeptide DC3 using 2kux.1.A as the template. Then molecular docking, molecular dynamics (MD) simulations, and molecular mechanics/generalized Born surface area (MM-GBSA) methods were performed to determine the bind site and explore the detailed interaction mechanism of DC3-AR complex. The obtained results suggested that the site formed by H11, loop888-893, and H12 (site 2) was the most possible position of DC3 binding to AR. Besides, hydrogen bonds, hydrophobic, and electrostatic interactions play dominant roles in the recognition and combination of DC3-AR complex. The essential residues dominant in each interaction were specifically revealed. This work facilitates our understanding of the interaction mechanism of DC3 binding to AR at the molecular level and contributes to the rational cyclopeptide drug design for prostate cancer.

Germline Variant in HSD3B1 (1245 A > C) and Response to Abiraterone Acetate Plus Prednisone in Men With New-Onset Metastatic Castration-Resistant Prostate Cancer

BACKGROUND

The HSD3B1 gene encodes the enzyme 3β-hydroxysteroid dehydrogenase-1 (3βHSD1), which catalyzes adrenal androgen precursors into dihydrotestosterone, the most potent androgen. Recently, the HSD3B1 (1245C) variant was shown to predict shorter duration of response to androgen deprivation therapy with medical or surgical castration in the setting of castration-sensitive prostate cancer (CSPC). The HSD3B1 (1245C) variant also predicts longer duration of response to ketoconazole in men with castration-resistant prostate cancer (CRPC). We hypothesized that the HSD3B1 (1245C) variant predicts response to treatment with abiraterone acetate (AA) and can help personalize treatment in men with advanced prostate cancer.

METHODS

Clinical data and samples were from a prospectively maintained prostate cancer registry at the University of Utah. Genotyping was performed. The primary study end point was progression-free survival in first-line AA in men with metastatic CRPC. We performed prespecified multivariate analyses to assess the independent predictive value of HSD3B1 genotype on progression-free survival on AA.

RESULTS

Seventy-six men with metastatic CRPC treated with first-line AA were included. In multivariate analysis, the HSD3B1 (1245C) variant did not predict response to first-line AA.

CONCLUSION

The HSD3B1 (1245C) variant does not predict response to first-line AA in metastatic CRPC. This finding could be due to the ability of AA metabolites to act as both agonist (3-keto-5α-abiraterone) and antagonist (Δ4-abiraterone) on androgen signaling.

Comparison of Abiraterone Acetate and Docetaxel with Androgen Deprivation Therapy in High-risk and Metastatic Hormone-naïve Prostate Cancer: A Systematic Review and Network Meta-analysis

CONTEXT

Randomized clinical trials have recently examined the benefit of adding docetaxel or abiraterone to androgen deprivation therapy (ADT) in hormone-naïve advanced prostate cancer (PCa).

OBJECTIVE

To perform a systematic review and network meta-analysis of randomized clinical trials, indirectly evaluating overall survival (OS) for men treated with abiraterone acetate plus prednisone/prednisolone with ADT (Abi-ADT) versus docetaxel with ADT (Doce-ADT) in hormone-naïve high-risk and metastatic PCa.

EVIDENCE ACQUISITION

Medline, Embase, Web of Science, Scopus, and Clinicaltrials.gov databases were searched in August 2017. We pooled results using the inverse variance technique and random-effects models. The Bucher technique for indirect treatment comparison was used to compare Abi-ADT with Doce-ADT. A priori subgroup and sensitivity analyses were performed.

EVIDENCE SYNTHESIS

Overall, 6067 patients from five trials were included: 1181 (19.5%) patients who received Doce-ADT, 1557 (25.7%) patients who received Abi-ADT, and 3329 (54.9%) patients who received ADT-alone. There was a total of 1921 deaths: 391 in the Doce-ADT group, 353 in the Abi-ADT group, and 1177 in the ADT-only group. The pooled hazard ratio (HR) for OS was 0.75 (95% confidence interval [CI]: 0.63-0.91, I²=51%, 3 trials, 2951 patients) for Doce-ADT versus ADT-alone and 0.63 (95% CI: 0.55-0.72, I²=0%, 2 trials, 3116 patients) for Abi-ADT versus ADT-alone. The indirect comparison of Abi-ADT to Doce-ADT demonstrated no statistically significant difference in OS between these approaches (HR: 0.84, 95% CI: 0.67-1.06). Findings were similar in various a priori subset analyses, including patients with metastatic disease. Bayesian analyses demonstrated comparable results (HR: 0.83, 95% CI: 0.63-1.16). Despite the lack of statistical significance, Surface Under the Cumulative Ranking Analysis demonstrated an 89% probability that Abi-ADT was preferred.

CONCLUSIONS

We did not identify a significant difference in OS between Abi-ADT and Doce-ADT for men with hormone-naïve high-risk or metastatic PCa, although Bayesian analysis demonstrates a high likelihood that Abi-ADT was preferred.

PATIENT SUMMARY

We synthesized the evidence available from studies examining the administration of docetaxel or abiraterone in combination with hormonal therapy for patients with newly diagnosed, advanced prostate cancer. While these studies did not directly compare these agents, we used methodological techniques to indirectly compare them and found no significant difference in overall survival.

Abiraterone plus Prednisone in Metastatic, Castration-Sensitive Prostate Cancer

BACKGROUND

Abiraterone acetate, a drug that blocks endogenous androgen synthesis, plus prednisone is indicated for metastatic castration-resistant prostate cancer. We evaluated the clinical benefit of abiraterone acetate plus prednisone with androgen-deprivation therapy in patients with newly diagnosed, metastatic, castration-sensitive prostate cancer.

METHODS

In this double-blind, placebo-controlled, phase 3 trial, we randomly assigned 1199 patients to receive either androgen-deprivation therapy plus abiraterone acetate (1000 mg daily, given once daily as four 250-mg tablets) plus prednisone (5 mg daily) (the abiraterone group) or androgen-deprivation therapy plus dual placebos (the placebo group). The two primary end points were overall survival and radiographic progression-free survival.

RESULTS

After a median follow-up of 30.4 months at a planned interim analysis (after 406 patients had died), the median overall survival was significantly longer in the abiraterone group than in the placebo group (not reached vs. 34.7 months) (hazard ratio for death, 0.62; 95% confidence interval [CI], 0.51 to 0.76; P<0.001). The median length of radiographic progression-free survival was 33.0 months in the abiraterone group and 14.8 months in the placebo group (hazard ratio for disease progression or death, 0.47; 95% CI, 0.39 to 0.55; P<0.001). Significantly better outcomes in all secondary end points were observed in the abiraterone group, including the time until pain progression, next subsequent therapy for prostate cancer, initiation of chemotherapy, and prostate-specific antigen progression (P<0.001 for all comparisons), along with next symptomatic skeletal events (P=0.009). These findings led to the unanimous recommendation by the independent data and safety monitoring committee that the trial be unblinded and crossover be allowed for patients in the placebo group to receive abiraterone. Rates of grade 3 hypertension and hypokalemia were higher in the abiraterone group.

CONCLUSIONS

The addition of abiraterone acetate and prednisone to androgen-deprivation therapy significantly increased overall survival and radiographic progression-free survival in men with newly diagnosed, metastatic, castration-sensitive prostate cancer. (Funded by Janssen Research and Development; LATITUDE ClinicalTrials.gov number, NCT01715285 .).

Inactivation of ID4 promotes a CRPC phenotype with constitutive AR activation through FKBP52

Castration-resistant prostate cancer (CRPC) is the emergence of prostate cancer cells that have adapted to the androgen-depleted environment of the prostate. In recent years, targeting multiple chaperones and co-chaperones (e.g., Hsp27, FKBP52) that promote androgen receptor (AR) signaling and/or novel AR regulatory mechanisms have emerged as promising alternative treatments for CRPC. We have shown that inactivation of inhibitor of differentiation 4 (ID4), a dominant-negative helix loop helix protein, promotes de novo steroidogenesis and CRPC with a gene expression signature that resembles constitutive AR activity in castrated mice. In this study, we investigated the underlying mechanism through which loss of ID4 potentiates AR signaling. Proteomic analysis between prostate cancer cell line LNCaP (L+ns) and LNCaP lacking ID4 (L(-)ID4) revealed elevated levels of Hsp27 and FKBP52, suggesting a role for these AR-associated co-chaperones in promoting constitutively active AR signaling in L(-)ID4 cells. Interestingly, protein interaction studies demonstrated a direct interaction between ID4 and the 52-kDa FK506-binding protein (FKBP52) in vitro, but not with AR. An increase in FKBP52-dependent AR transcriptional activity was observed in L(-)ID4 cells. Moreover, pharmacological inhibition of FKBP52-AR signaling, by treatment with MJC13, attenuated the tumor growth, weight, and volume in L(-)ID4 xenografts. Together, our results demonstrate that ID4 selectively regulates AR activity through direct interaction with FKBP52, and its loss, promotes CRPC through FKBP52-mediated AR signaling.

Crosstalk of the Androgen Receptor with Transcriptional Collaborators: Potential Therapeutic Targets for Castration-Resistant Prostate Cancer

Prostate cancer is the second leading cause of death from cancer among males in Western countries. It is also the most commonly diagnosed male cancer in Japan. The progression of prostate cancer is mainly influenced by androgens and the androgen receptor (AR). Androgen deprivation therapy is an established therapy for advanced prostate cancer; however, prostate cancers frequently develop resistance to low testosterone levels and progress to the fatal stage called castration-resistant prostate cancer (CRPC). Surprisingly, AR and the AR signaling pathway are still activated in most CRPC cases. To overcome this problem, abiraterone acetate and enzalutamide were introduced for the treatment of CRPC. Despite the impact of these drugs on prolonged survival, CRPC acquires further resistance to keep the AR pathway activated. Functional molecular studies have shown that some of the AR collaborative transcription factors (TFs), including octamer transcription factor (OCT1), GATA binding protein 2 (GATA2) and forkhead box A1 (FOXA1), still stimulate AR activity in the castration-resistant state. Therefore, elucidating the crosstalk between the AR and collaborative TFs on the AR pathway is critical for developing new strategies for the treatment of CRPC. Recently, many compounds targeting this pathway have been developed for treating CRPC. In this review, we summarize the AR signaling pathway in terms of AR collaborators and focus on pyrrole-imidazole (PI) polyamide as a candidate compound for the treatment of prostate cancer.

Review: Placental adaptations to the presence of maternal asthma during pregnancy

Asthma is a highly prevalent chronic medical condition affecting an estimated 12% of pregnant, women each year, with prevalence of asthma greatest (up to 16%) among the socially disadvantaged. Maternal asthma is associated with significant perinatal morbidity and mortality including preterm births, neonatal hospitalisations and low birthweight outcomes each year. We have identified that the placenta adapts to the presence of chronic, maternal asthma during pregnancy in a sex specific manner that may confer sex differences in fetal outcome. The male fetus was at greater risk of a poor outcome than a female fetus in the presence of maternal asthma and an acute inflammatory event such as an asthma exacerbation. This review will examine the role of sex specific differences in placental function on fetal growth and survival.

Androgen receptor variation affects prostate cancer progression and drug resistance

Significant therapeutic progress has been made in treating prostate cancer in recent years. Drugs such as enzalutamide, abiraterone, and cabazitaxel have expanded the treatment armamentarium, although it is not completely clear which of these drugs are the most-effective option for individual patients. Moreover, such advances have been tempered by the development of therapeutic resistance. The purpose of this review is to summarize the current literature pertaining to the biochemical effects of AR variants and their consequences on prostate cancer therapies at both the molecular level and in clinical treatment. We address how these AR splice variants and mutations affect tumor progression and therapeutic resistance and discuss potential novel therapeutic strategies under development. It is hoped that these therapies can be administered with increasing precision as tumor genotyping methods become more sophisticated, thereby lending clinicians a better understanding of the underlying biology of prostate tumors in individual patients.

Design and evaluation of novel oxadiazole derivatives as potential prostate cancer agents

Various 1,3,4-oxadiazole derivatives have been synthesized and their antiproliferative properties have been studied. The in vitro screening was performed against androgen dependent (LNCaP) and androgen independent (PC-3) prostate cancer cell lines. Most of the compounds showed promising activity. Among them, compounds 2d (IC50=0.22 and 1.3μM) and 2a (IC50=8.34 and 2,5μM) have shown significant activities on PC-3 and LNCaP cell lines respectively. To investigate the mechanism of cell death we performed cell apoptosis staining and cell cycle arrest assay on more sensitive PC-3 cell lines on 2d. The results demonstrated that 2d induced apoptosis and shifted the cells to the sub G0/G1 and S phase. Our study evidently identified the potency of compound 2d as potential anti-prostate cancer agent.

The importance of non-nuclear AR signaling in prostate cancer progression and therapeutic resistance

The androgen receptor (AR) remains the major oncogenic driver of prostate cancer, as evidenced by the efficacy of androgen deprivation therapy (ADT) in naïve patients, and the continued effectiveness of second generation ADTs in castration resistant disease. However, current ADTs are limited to interfering with AR ligand binding, either through suppression of androgen production or the use of competitive antagonists. Recent studies demonstrate 1) the expression of constitutively active AR splice variants that no longer depend on androgen, and 2) the ability of AR to signal in the cytoplasm independently of its transcriptional activity (non-genomic); thus highlighting the need to consider other ways to target AR. Herein, we review canonical AR signaling, but focus on AR non-genomic signaling, some of its downstream targets and how these effectors contribute to prostate cancer cell behavior. The goals of this review are to 1) re-highlight the continued importance of AR in prostate cancer as the primary driver, 2) discuss the limitations in continuing to use ligand binding as the sole targeting mechanism, 3) discuss the implications of AR non-genomic signaling in cancer progression and therapeutic resistance, and 4) address the need to consider non-genomic AR signaling mechanisms and pathways as a viable targeting strategy in combination with current therapies.

Gene interference strategies as a new tool for the treatment of prostate cancer

Prostate cancer (PCa) is one of the most common cancer in men. It affects older men and the incidence increases with age; the median age at diagnosis is 67 years. The diagnosis of PCa is essentially based on three tools: digital rectal exam, serum concentration of prostate specific antigen, and transrectal ultrasound-guided biopsy. Currently, the therapeutic treatments of this cancer are different and range from the prostatectomy to hormonal therapy, to radiation therapy, to immunotherapy, and to chemotherapy. However, additional efforts are required in order to find new weapons for the treatment of metastatic setting of disease. The purpose of this review is to highlight new therapeutic strategies based on gene interference; in fact, numerous siRNA and miRNA in the therapeutic treatment of PCa are reported below.

The FKBP52 Cochaperone Acts in Synergy with β-Catenin to Potentiate Androgen Receptor Signaling

FKBP52 and β-catenin have emerged in recent years as attractive targets for prostate cancer treatment. β-catenin interacts directly with the androgen receptor (AR) and has been characterized as a co-activator of AR-mediated transcription. FKBP52 is a positive regulator of AR in cellular and whole animal models and is required for the development of androgen-dependent tissues. We previously characterized an AR inhibitor termed MJC13 that putatively targets the AR BF3 surface to specifically inhibit FKBP52-regulated AR signaling. Predictive modeling suggests that β-catenin interacts with the AR hormone binding domain on a surface that overlaps with BF3. Here we demonstrate that FKBP52 and β-catenin interact directly in vitro and act in concert to promote a synergistic up-regulation of both hormone-independent and -dependent AR signaling. Our data demonstrate that FKBP52 promotes β-catenin interaction with AR and is required for β-catenin co-activation of AR activity in prostate cancer cells. MJC13 effectively blocks β-catenin interaction with the AR LBD and the synergistic up-regulation of AR by FKBP52 and β-catenin. Our data suggest that co-regulation of AR by FKBP52 and β-catenin does not require FKBP52 PPIase catalytic activity, nor FKBP52 binding to Hsp90. However, the FKBP52 proline-rich loop that overhangs the PPIase pocket is critical for synergy.

Enzalutamide: a new prostate cancer targeted therapy against the androgen receptor

Enzalutamide (MDV3100), an androgen receptor-signalling inhibitor, represents the most recent compound added to the therapeutic armamentarium for the treatment of metastatic castration-resistant prostate cancer (mCRPC) who progressed to docetaxel. The anti-tumour activity and safety of enzalutamide has been demonstrated in a phase III clinical trial, showing a benefit in overall survival, which was the primary endpoint. There are no head-to-head studies comparing the different treatment options in this subset of patients. In this article, most relevant data published in the literature have been reviewed, with special attention to the therapeutic alternatives currently available for postdocexatel mCRPC patients, emphasising the mechanisms of action of the different drugs, efficacy and quality of life-related aspects.

Limited in vitro efficacy of CYP17A1 inhibition on human castration resistant prostate cancer

Although accumulating evidence indicates high expression of CYP17A1(P45017A1) allows castration resistant prostate cancer (CRPC) to maintain high intratumoral androgen levels, the potential P45017A1 activity has not been characterized yet. The aim of this study was to examine the potential CYP17A1 activity including 17α-hydroxylase and 17,20-lyase activities in human CRPC and the effect of a CYP17A inhibitor. We used three human CRPC cell lines: C4-2 and C4-2AT6 which was established from C4-2 under androgen ablation conditions for 6months, and PC3. To ascertain the potential CYP17A1 activity, we cultured with the steroid precursors: (13)C-[2,3,4]-progesterone (13C-Prog), and analyzed the sequential biosynthesis (13)C-[2,3,4]-17-hydroxyprogesterone (13C-17OHP) and (13)C-[2,3,4]-androstenedione(13C-Adione) by liquid chromatography/mass spectrometry (LC/MS/MS).The C4-2AT6 cells showed significantly higher CYP17A1 expression than C4-2 cells (p<0.001). LC/MS/MS analysis enabled us to detect the 13C-17-OHP and 13C-A-dione in these cell lines. The concentration ratio of 13C-Adione/13C-17OHP (Adione-17OHP ratio), which is thought to reflect the differences between 17-hydroxylase and 17,20-lyase activities, was then determined. The Adione-17OHP ratio in C4-2AT6 cells was significantly higher than that of C4-2 cells (p<0.001). Abiraterone were able to inhibit the CYP17A activities, although abiraterone did not have anti-proliferative effects on C4-2 and C4-2AT6 cells at clinically achievable concentrations of <1000nM in vitro. The present study clearly demonstrates CRPC have the dual activities of CYP17A1 mediated by 17-hydroxylase activity and 17,20-lyase activity. Abiraterone doesn't have an in vitro anti-proliferative efficacy in CRPC cells, suggesting limited efficacy in vitro.

Review of novel therapeutic medicines targeting androgen signaling in castration-resistant prostate cancer

Prostate cancer is the most common male malignant neoplasm. Androgens and the androgen receptor (AR) play a key role in the onset and progression of prostate cancer. The expression of the AR is still preserved in the majority of patients with castration-resistant prostate cancer (CRPC). CRPC is considered to be induced by the following mechanisms: (1) sustained AR activation by enhancing intracellular conversion of adrenal androgens to dehydrotestosterone via a de novo route; (2) AR hypersensitivity; (3) promiscuous activation of AR signaling; and (4) outlaw pathways. Recent advances in the treatment of CRPC include novel medicines targeting AR signaling pathways. In addition, functional molecular studies have shown that some of the AR-regulated genes and AR coregulators are prognostic markers and potential therapeutic targets for prostate cancer, particularly in the castration-resistant state. Therefore, identification of the AR signaling pathways responsible for establishment of CRPC is critical for developing new strategies for the treatment of CRPC.

Phase-1 study of abiraterone acetate in chemotherapy-naïve Japanese patients with castration-resistant prostate cancer

Persistent androgen synthesis under castration status in adrenal gland, testes and tumor cells is thought to be one of the major causes of development and progression of castration-resistant prostate cancer (CRPC). Abiraterone acetate (AA), the prodrug of abiraterone, which is an inhibitor of androgen synthesis enzymes, was evaluated for pharmacokinetics, pharmacodynamics, preliminary efficacy and safety in Japanese patients with CRPC in a phase-1, open-label and dose-escalation study. Chemotherapy-naïve Japanese CRPC patients (N = 27) received one of four AA daily doses (250 mg [n = 9], 500 mg [n = 6], 1000 [1 h premeal] mg [n = 6] and 1000 [2 h postmeal] mg [n = 6]) continuously through 28-day treatment cycles. In the first cycle, AA monotherapy was given on days 1–7 for pharmacokinetics, and AA plus prednisone (5 mg twice daily) from days 8 to 28. Of 27 patients, 9 continued treatment with AA until the data cut-off date (18 July 2013). Over the evaluated dose range, plasma abiraterone concentrations increased with dose, with median t_max 2–3 h. At each dose level, mean serum corticosterone concentrations increased, while testosterone and dehydroepiandrosterone sulfate concentrations rapidly decreased following a single AA dose and were further reduced to near the quantification limit on day 8 regardless of the dose. At least 3 patients from each dose-group experienced ≥50% prostate-specific antigen reduction, suggesting clinical benefit from AA in Japanese CRPC patients. AA was generally well-tolerated, and, therefore, the recommended AA dosage regimen in Japanese CRPC patients is 1000 mg oral dose under modified fasting conditions (at least 1 h premeal or 2 h postmeal). This study is registered at ClinicalTrials.gov: NCT01186484.

Abiraterone acetate: a review of its use in patients with metastatic castration-resistant prostate cancer

Abiraterone acetate (Zytiga(®)) is an orally administered, selective inhibitor of the 17α-hydroxylase and C17,20-lyase enzymatic activities of cytochrome P450 (CYP) 17. CYP17 is required for androgen biosynthesis, with androgen receptor signalling crucial in the progression from primary to metastatic prostate cancer. Abiraterone acetate is approved in the European Union and the US, in combination with prednisone or prednisolone, for the treatment of men with metastatic castration-resistant prostate cancer (CRPC). When administered in combination with prednisone in a placebo-controlled, multinational phase III study, abiraterone acetate significantly prolonged overall survival and radiographic progression-free survival (rPFS) in men with metastatic CRPC who had previously received docetaxel. In men with metastatic CRPC who had not previously received chemotherapy participating in a placebo-controlled, multinational phase III study, there was a strong trend towards an overall survival benefit, a significant prolongation in rPFS and significant delays in clinical decline, the need for chemotherapy and the onset of pain observed. Given the nature of the therapy, the overall tolerability profile of abiraterone acetate, in combination with prednisone, was acceptable in men with metastatic CRPC. Abiraterone acetate is associated with hypokalaemia, hypertension, and fluid retention or oedema, secondary to its mechanism of action, and with cardiac adverse events and hepatotoxicity; however, in the phase III studies the incidences of the most frequently reported grade 3 or 4 adverse events of special interest were relatively low. Although the final overall survival data in men with metastatic CRPC who have not previously received chemotherapy are awaited, current evidence indicates that abiraterone acetate is a useful option for the treatment of metastatic CRPC.

Androgen synthesis inhibitors in the treatment of castration-resistant prostate cancer

Suppression of gonadal testosterone synthesis represents the standard first line therapy for treatment of metastatic prostate cancer. However, in the majority of patients who develop castration-resistant prostate cancer (CRPC), it is possible to detect persistent activation of the androgen receptor (AR) through androgens produced in the adrenal gland or within the tumor itself. Abiraterone acetate was developed as an irreversible inhibitor of the dual functional cytochrome P450 enzyme CYP17 with activity as a 17α-hydroxylase and 17,20-lyase. CYP17 is necessary for production of nongonadal androgens from cholesterol. Regulatory approval of abiraterone in 2011, based on a phase III trial showing a significant improvement in overall survival (OS) with abiraterone and prednisone versus prednisone, represented proof of principle that targeting AR is essential for improving outcomes in men with CRPC. Inhibition of 17α-hydroxylase by abiraterone results in accumulation of upstream mineralocorticoids due to loss of cortisol-mediated suppression of pituitary adrenocorticotropic hormone (ACTH), providing a rationale for development of CYP17 inhibitors with increased specificity for 17,20-lyase (orteronel, galeterone and VT-464) that can potentially be administered without exogenous corticosteroids. In this article, we review the development of abiraterone and other CYP17 inhibitors; recent studies with abiraterone that inform our understanding of clinical parameters such as drug effects on quality-of-life, potential early predictors of response, and optimal sequencing of abiraterone with respect to other agents; and results of translational studies providing insights into resistance mechanisms to CYP17 inhibitors leading to clinical trials with drug combinations designed to prolong abiraterone benefit or restore abiraterone activity.

Nrf1 and Nrf2 transcription factors regulate androgen receptor transactivation in prostate cancer cells

Despite androgen deprivation therapy (ADT), persistent androgen receptor (AR) signaling enables outgrowth of castration resistant prostate cancer (CRPC). In prostate cancer (PCa) cells, ADT may enhance AR activity through induction of oxidative stress. Herein, we investigated the roles of Nrf1 and Nrf2, transcription factors that regulate antioxidant gene expression, on hormone-mediated AR transactivation using a syngeneic in vitro model of androgen dependent (LNCaP) and castration resistant (C4-2B) PCa cells. Dihydrotestosterone (DHT) stimulated transactivation of the androgen response element (ARE) was significantly greater in C4-2B cells than in LNCaP cells. DHT-induced AR transactivation was coupled with higher nuclear translocation of p65-Nrf1 in C4-2B cells, as compared to LNCaP cells. Conversely, DHT stimulation suppressed total Nrf2 levels in C4-2B cells but elevated total Nrf2 levels in LNCaP cells. Interestingly, siRNA mediated silencing of Nrf1 attenuated AR transactivation while p65-Nrf1 overexpression enhanced AR transactivation. Subsequent studies showed that Nrf1 physically interacts with AR and enhances AR’s DNA-binding activity, suggesting that the p65-Nrf1 isoform is a potential AR coactivator. In contrast, Nrf2 suppressed AR-mediated transactivation by stimulating the nuclear accumulation of the p120-Nrf1 which suppressed AR transactivation. Quantitative RT-PCR studies further validated the inductive effects of p65-Nrf1 isoform on the androgen regulated genes, PSA and TMPRSS2. Therefore, our findings implicate differential roles of Nrf1 and Nrf2 in regulating AR transactivation in PCa cells. Our findings also indicate that the DHT-stimulated increase in p65-Nrf1 and the simultaneous suppression of both Nrf2 and p120-Nrf1 ultimately facilitates AR transactivation in CRPC cells.

Castrate-resistant prostate cancer: postdocetaxel management

PURPOSE OF REVIEW

Prior to 2010, docetaxel was the only treatment shown to prolong survival in metastatic castrate-resistant prostate cancer (CRPC). In the past 3 years, several therapeutic agents have demonstrated survival improvements for CRPC after the receipt of prior docetaxel, leading to multiple approvals by the US Food and Drug Administration.

RECENT FINDINGS

The development of these novel agents, each with a distinct mechanism of action, is the fruition of sedulous preclinical research and well designed clinical trials. Cabazitaxel, a next generation taxane, was the first Food and Drug Administration-approved drug for the postdocetaxel setting. The recognition of sustained androgen dependence of CRPC has led to the identification of more potent and selective inhibitors of androgen synthesis and androgen-receptor signaling, such as abiraterone and enzalutamide, respectively. Radium-223, an α-emitting radionuclide still under regulatory review, recently showed a significant survival benefit for CRPC. Finally, sipuleucel-T, a form of immunotherapy, may benefit a subset of patients in the postdocetaxel setting.

SUMMARY

Post-docetaxel management of CRPC has undergone a dramatic yet welcome paradigm change in the past 3 years. With multiple life-prolonging agents available, it now becomes imperative to coordinate how and when these new therapies should be used and sequenced to achieve optimal patient outcomes.

Targeting the adrenal gland in castration-resistant prostate cancer: a case for orteronel, a selective CYP-17 17,20-lyase inhibitor

Androgen and the androgen receptor (AR) pathway remain the key targets for emerging new therapies against castration-resistant prostate cancer (CRPC). Adrenal androgens and intratumoral testosterone production appear to be sufficient to activate AR in the castration-resistant setting. This process re-engages AR and allows it to continue to be the primary target responsible for prostate cancer progression. Adrenal androgen production can be blocked by inhibiting cytochrome P450 17α-hydroxylase/17,20-lyase (CYP17), a key enzyme for androgen synthesis in adrenal glands and peripheral tissues. Therapeutic CYP17 inhibition by ketoconazole or by the recently approved adrenal inhibitor abiraterone acetate is the only available choice to target this pathway in CRPC. A new CYP17 inhibitor, with more selective inhibition of 17,20-lyase over 17α-hydroxylase, orteronel (TAK-700), is currently undergoing phase III clinical trials in pre- and postchemotherapy CRPC. In a completed phase II trial in CRPC patients, orteronel demonstrated its efficacy by lowering the levels of circulating androgens, reducing prostate-specific antigen (PSA) levels, and decreasing the levels of circulating tumor cells. Ongoing studies evaluating orteronel in CRPC will further define its safety and role in the management of this disease.

Human castration resistant prostate cancer rather prefer to decreased 5α-reductase activity

Physiologically relevant steroid 5α-reductase (SRD5A) activity that is essential for dihydrotestosterone (DHT) biosynthesis in human castration-resistant prostate cancer (CRPC) has not been fully characterized yet. In this study to ascertain the potential SRD5A activity, we cultured two human CRPC cell lines, C4-2 and C4-2AT6, with the steroid precursor: ¹³C-[2,3,4]-androstenedione (13C-Adione), and analyzed the sequential biosynthesis of ¹³C-[2,3,4]-testosterone (13C-T) and ¹³C-[2,3,4]-DHT (13C-DHT) by liquid chromatography/mass spectrometry (LC/MS/MS). The 13C-DHT/13C-T concentration ratio detected by LC/MS/MS in C4-2AT6 cells appeared to reflect the SRD5A activity. The ratio in C4-2AT6 was significantly lower than that in C4-2. An increased concentration of DHT did not have a positive effect on cell proliferation, rather it exhibited inhibitory effects. 5α-reductase inhibitors did not have any inhibitory effect at clinically achievable concentrations. These results indicate that CRPC cells may have an unknown regulation system to protect themselves from an androgenic suppressive effect mediated by SRD5A activity.

Targeting the androgen receptor with siRNA promotes prostate cancer metastasis through enhanced macrophage recruitment via CCL2/CCR2-induced STAT3 activation

Increased CCL2 expression in prostate cancer (PCa) cells enhanced metastasis via macrophage recruitment. However, its linkage to androgen receptor (AR)-mediated PCa progression remains unclear. Here, we identified a previously unrecognized regulation: targeting AR with siRNA in PCa cells increased macrophage recruitment via CCL2 up-regulation, which might then result in enhancing PCa invasiveness. Molecular mechanism dissection revealed that targeting PCa AR with siRNA promoted PCa cell migration/invasion via CCL2-dependent STAT3 activation and epithelial–mesenchymal transition (EMT) pathways. Importantly, pharmacologic interruption of the CCL2/CCR2-STAT3 axis suppressed EMT and PCa cell migration, providing a new mechanism linking CCL2 and EMT. Simultaneously targeting PCa AR with siRNA and the CCL2/CCR2-STAT3 axis resulted in better suppression of PCa growth and metastasis in a xenograft PCa mouse model. Human PCa tissue microarray analysis suggests that increased CCL2 expression may be potentially associated with poor prognosis of PCa patients. Together, these results may provide a novel therapeutic approach to better battle PCa progression and metastasis at the castration resistant stage via the combination of targeting AR with siRNA and anti-CCL2/CCR2-STAT3 signalling.

A co-clinical approach identifies mechanisms and potential therapies for androgen deprivation resistance in prostate cancer

Here we report an integrated analysis that leverages data from treatment of genetic mouse models of prostate cancer along with clinical data from patients to elucidate new mechanisms of castration resistance. We show that castration counteracts tumor progression in a Pten-loss driven mouse model of prostate cancer through the induction of apoptosis and proliferation block. Conversely, this response is bypassed upon deletion of either Trp53 or Lrf together with Pten, leading to the development of castration resistant prostate cancer (CRPC). Mechanistically, the integrated acquisition of data from mouse models and patients identifies the expression patterns of XAF1-XIAP/SRD5A1 as a predictive and actionable signature for CRPC. Importantly, we show that combined inhibition of XIAP, SRD5A1, and AR pathways overcomes castration resistance. Thus, our co-clinical approach facilitates stratification of patients and the development of tailored and innovative therapeutic treatments.

Effect of a novel 17,20-lyase inhibitor, orteronel (TAK-700), on androgen synthesis in male rats

Endogenous androgens play a role in the development and progression of prostate cancer (PC), thus androgen suppression may offer an effective therapeutic strategy for this disease. Orteronel (TAK-700), 6-[(7S)-7-hydroxy-6,7-dihydro-5H-pyrrolo[1,2-c]imidazol-7-yl]-N-methyl-2-naphthamide, is a novel, non-steroidal, selective inhibitor of the 17,20-lyase activity of CYP17A--a key enzyme in the production of steroidal hormones--and is being developed as a therapy for PC. The purpose of this study was to elucidate the inhibitory activity of orteronel, in particular its specificity for androgen synthesis enzymes, in male rats--an androgen-synthesis model that largely reflects this pathway in humans. Orteronel inhibited 17,20-lyase activity in rats with an IC(50) of 1200 nM but did not inhibit 17α-hydroxylase or 11β-hydroxylase (CYP11B1) activity in rats at concentrations up to 10 μM. In cellular steroidogenesis assays using rat testicular cells, orteronel suppressed testosterone and androstenedione production with an IC(50) of 640 nM and 210 nM, respectively, but did not suppress either corticosterone or aldosterone production in rat adrenal cells at concentrations up to 30 μM. In addition, serum testosterone and androstenedione levels in human chorionic gonadotropin-injected hypophysectomized rats were significantly reduced by single oral administration of orteronel at a dose of 30 mg/kg (both p ≤ 0.01); serum corticosterone and aldosterone levels in ACTH-injected hypophysectomized rats did not result in significant differences compared with controls, following orteronel administration at doses up to 300 mg/kg. Serum testosterone levels in intact male rats were significantly reduced by orteronel 4h after dosing at 100mg/kg (p ≤ 0.01); testosterone levels showed a tendency to recover afterward. In intact male rats, the weight of the prostate glands and seminal vesicles was decreased in a dose-dependent manner following multiple doses of orteronel at 37.5, 150, and 600 mg/kg, TID for 4 days. The reversibility of orteronel was further confirmed using a human adrenocortical tumor cell line. In summary, orteronel is a selective and reversible 17,20-lyase inhibitor, and decreases the weight of androgen-dependent organs in male rats. Our data suggests that orteronel would therefore be effective for androgen-dependent disorders such as PC.