The genetics of castration-resistant prostate cancer: what can the germline tell us?

Embryologic and hormonal contributors to prostate cancer in transgender women

Transgender women, who were assigned male at birth but identify as women, may take several steps to merge their physical and psychological identities, including gender-affirming surgeries and hormone therapy. With the presence of the mature prostate gland there persists a risk for malignant transformation in this population. The recognition by the medical community and society at large that transgender women are at risk of developing prostate cancer has recently been supported by investigative efforts. The slowly emerging clinical evidence suggests that the disease is likely to be more aggressive than in cisgender men, with 6 of 9 published cases discussing metastasis reporting metastatic disease on presentation. Currently the overall prevalence appears low, pointing to evolving awareness, educational status, socioeconomic status, and late presentation. This commentary focuses on exploring the factors contributing to the incidence of prostate cancer and the biochemical and endocrine mechanisms that lead to aggressive prostate tumor development in transgender women.

Meta-analysis of CDKN2A methylation to find its role in prostate cancer development and progression, and also to find the effect of CDKN2A expression on disease-free survival (PRISMA)

BACKGROUND

Reduction of cyclin-dependent kinase inhibitor 2A (CDKN2A) (p16 and p14) expression through DNA methylation has been reported in prostate cancer (PCa). This meta-analysis was conducted to assess the difference of p16 and p14 methylation between PCa and different histological types of nonmalignant controls and the correlation of p16 or p14 methylation with clinicopathological features of PCa.

METHODS

According to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement criteria, articles were searched in PubMed, Embase, EBSCO, Wanfang, and CNKI databases. The strength of correlation was calculated by the pooled odds ratios (ORs) and their corresponding 95% confidence intervals (95% CIs). Trial sequential analysis (TSA) was used to estimate the required population information for significant results.

RESULTS

A total of 20 studies published from 1997 to 2017 were identified in this meta-analysis, including 1140 PCa patients and 530 cases without cancer. Only p16 methylation in PCa was significantly higher than in benign prostatic lesions (OR = 4.72, P = .011), but had a similar level in PCa and adjacent tissues or high-grade prostatic intraepithelial neoplasias (HGPIN). TSA revealed that this analysis on p16 methylation is a false positive result in cancer versus benign prostatic lesions (the estimated required information size of 5116 participants). p16 methylation was not correlated with PCa in the urine and blood. Besides, p16 methylation was not linked to clinical stage, prostate-specific antigen (PSA) level, and Gleason score (GS) of patients with PCa. p14 methylation was not correlated with PCa in tissue and urine samples. No correlation was observed between p14 methylation and clinical stage or GS. CDKN2A mutation and copy number alteration were not associated with prognosis of PCa in overall survival and disease-free survival. CDKN2A expression was not correlated with the prognosis of PCa in overall survival (492 cases) (P > .1), while CDKN2A expression was significantly associated with a poor disease-free survival (P < .01).

CONCLUSION

CDKN2A methylation may not be significantly associated with the development, progression of PCa. Although CDKN2A expression had an unfavorable prognosis in disease-free survival. More studies are needed to confirm our results.

Survival Outcomes of Concurrent Treatment with Docetaxel and Androgen Deprivation Therapy in Metastatic Castration-Resistant Prostate Cancer

PURPOSE

Docetaxel-based chemotherapy (DTX) improves overall survival (OS) of men with metastatic castration-resistant prostate cancer (mCRPC). Considering the potential existence of androgen receptors that remain active at this stage, we aimed to assess the impact of the combined use of androgen deprivation therapy (ADT) with DTX for mCRPC.

MATERIALS AND METHODS

We performed a single-institutional retrospective analysis of patients with mCRPC who received either DTX alone (DTX group, n=21) or concurrent DTX and ADT (DTX+ADT group, n=26) between August 2006 and February 2014. All patients received DTX doses of 75 mg/m² every three weeks for at least three cycles. In the DTX+ADT group, all patients used luteinizing hormone releasing hormone agonist continuously as a concurrent ADT.

RESULTS

The median follow-up period was 24.0 months (interquartile range 12.0-37.0) for the entire cohort. The median radiographic progression-free survival (rPFS) was 9.0 months and 6.0 months in the DTX+ADT and DTX groups, respectively (log-rank p=0.036). On multivariable Cox regression analysis, concurrent administration of ADT was the only significant predictor of rPFS [hazard ratio (HR)=0.525, 95% confidence intervals (CI) 0.284-0.970, p=0.040]. The median OS was 42.0 and 38.0 months in the DTX+ADT and DTX groups, respectively (log-rank p=0.796). On multivariable analysis, hemoglobin level at the time of DTX initiation was associated with OS (HR=0.532, 95% CI 0.381-0.744, p<0.001).

CONCLUSION

In chemotherapy-naive patients with mCRPC, the combined use of ADT with DTX improved rPFS. Our result suggests that the concurrent administration of ADT and DTX is superior to DTX alone.

Real-World Treatment Patterns in Men with Castration- Resistant Prostate Cancer Receiving Docetaxel

Background: Docetaxel has been a standard of care for castration-resistant prostate cancer (CRPC) in the United States since 2004, yet little has been reported on its patterns of use in routine practice. To help understand these patterns, a retrospective study was conducted and is reported here. Methods: Medical records from 394 patients treated in the United States were reviewed. Data were collected by 48 physicians from oncology (patient N=344) and 8 physicians from urology (patient N=50) practices. Inclusion criteria were: CRPC diagnosed between 2004 and 2010; received docetaxel; discontinued docetaxel due to rising prostate-specific antigen (PSA), progression of bone lesions, or progression of nodal or visceral metastases. Data were collected from physicians using an internet-based case report form. We evaluated patient demographics, characteristics of the docetaxel regimen, and other treatments used until docetaxel discontinuation. Results: Patients had a mean [±SD] age of 66.5 [8.9] years, the majority (63%) were white, and geographic dispersion was similar to the US population. The majority of patients initiated docetaxel between 2008 and 2010. After CRPC diagnosis, 8% of patients had initiated another cancer-directed therapy before starting docetaxel. Most (78.9%) patients initiated docetaxel with prednisone, while 18.5% initiated docetaxel alone and 2.6% initiated with other medications. Half of patients initiated docetaxel within 1 month after CRPC diagnosis, while 25% started ≥6 months later. Other non-chemotherapy treatments used with docetaxel were hormonal therapy (22.8%), radiotherapy (17.3%), and surgery (4.1%). Most patients (75%) received ≥4 docetaxel cycles, half received ≥6 cycles, 25% received ≥8 cycles and 10% received ≥10 cycles. Increased tumor mass, with/without new bone lesions or rising PSA, was the most common reason for docetaxel discontinuation (74% of patients). Conclusions: Concordant with guidelines, docetaxel and prednisone was the preferred first-line chemotherapy regimen in CRPC patients reviewed for this study. However, one quarter of patients did not initiate docetaxel until ≥6 months after CRPC diagnosis and total exposure varied considerably, with only 10% receiving ≥10 cycles. Future studies are needed to describe specific reasons explaining timing of docetaxel initiation and duration of exposure in some CRPC patients.

Distinct cancer-specific survival in metastatic prostate cancer patients classified by a panel of single nucleotide polymorphisms of cancer-associated genes

Individual genetic variations may have a significant influence on the survival of metastatic prostate cancer (PCa) patients. We aimed to identify target genes and their variations involved in the survival of PCa patients using a single nucleotide polymorphism (SNP) panel. A total of 185 PCa patients with bone metastasis at the initial diagnosis were analyzed. Germline DNA in each patient was genotyped using a cancer SNP panel that contained 1,421 SNPs in 408 cancer-related genes. SNPs associated with survival were screened by a log-rank test. Fourteen SNPs in 6 genes, XRCC4, PMS1, GATA3, IL13, CASP8, and IGF1, were identified to have a statistically significant association with cancer-specific survival. The cancer-specific survival times of patients grouped according to the number of risk genotypes of 6 SNPs selected from the 14 SNPs differed significantly (0-1 v. 2-3 v. 4-6 risk genotypes; P = 7.20 × 10(-8)). The high-risk group was independently associated with survival in a multivariate analysis that included conventional clinicopathological variables (P = 0.0060). We identified 14 candidate SNPs in 6 cancer-related genes, which were associated with poor survival in patients with metastatic PCa. A panel of SNPs may help predict the survival of those patients.

Challenges to improved therapeutics for metastatic castrate resistant prostate cancer: from recent successes and failures

Men with metastatic castration-resistant prostate cancer (mCRPC) carry poor prognosis despite the use of docetaxel-based regimens which has modest survival benefit shown by randomized clinical trials. Significant progress in the discovery of novel therapeutic agents has been made in the past few years. While sipuleucel-T, cabazitaxel, and abiraterone gained regulatory approval in 2010 and 2011, several highly promising candidates/regimens have failed in large scale clinical trials. Challenges remain to optimize the design and interpretation of clinical trial results and develop more effective strategies for mCRPC. In this review, we examined the positive and negative clinical trials in mCRPC in the past and discussed the various aspects of clinical trial design including selection of targets and appropriate outcome measures, biomarker development and implementation, and strategies for combination therapy.

Castration-resistant prostate cancer: new science and therapeutic prospects

There is a growing number of new therapies targeting different pathways that will revolutionize patient management strategies in castration-resistant prostate cancer (CRPC) patients. Today there are more clinical trial options for CRPC treatment than ever before, and there are many promising agents in late-stage clinical testing. The hypothesis that CRPC frequently remains driven by a ligand-activated androgen receptor (AR) and that CRPC tissues exhibit substantial residual androgen levels despite gonadotropin-releasing hormone therapy, has led to the evaluation of new oral compounds such as abiraterone and MDV 3100. Their results, coupled with promising recent findings in immunotherapy (eg sipuleucel-T) and with agents targeting angiogenesis (while awaiting the final results of the CALGB trial 90401) will most probably impact the management of patients with CRPC in the near future. Other new promising agents need further development. With our increased understanding of the biology of this disease, further trial design should incorporate improved patient selection so that patient populations are those who may be most likely to benefit from treatment.

Current treatment strategies for castration-resistant prostate cancer

Prostate cancer is the most common cancer in men in United States and the fifth most common cancer in men in Korea. Although the majority of patients with metastatic prostate cancer initially respond to androgen deprivation therapy, almost all patients will eventually progress to develop castration-resistant prostate cancer (CRPC). Treatment options for CRPC remain limited. Prostate cancer was considered unresponsive to chemotherapy until the mid-1990s, when mitoxantrone combined with prednisone was shown to play a role in the palliative treatment of patients with CRPC. In 2004, two large randomized clinical trials demonstrated for the first time a small but significant survival advantage of docetaxel-based chemotherapy compared with mitoxantrone in patients with metastatic CRPC. Recently, cabazitaxel was shown to improve survival in patients with metastatic CRPC who progressed after docetaxel-based chemotherapy. Sipuleucel-T was also demonstrated to improve overall survival in patients with asymptomatic or minimally symptomatic metastatic CRPC. Along with mitoxantrone and docetaxel, cabazitaxel and sipuleucel-T are now approved for use in metastatic CRPC by the US Food and Drug Administration. There have been multiple early-phase clinical trials of various agents for the treatment of CRPC, and some are in phase III development. This review focuses on the key clinical trials of various treatment options of CRPC currently in use and under investigation.

The evolving role of familial history for prostate cancer

BACKGROUND

family history of prostate cancer is a risk factor for prostate cancer occurrence. Differently from other neoplasms no major predisposing gene has been identified.

MATERIAL AND METHODS

this review article presents the controversial results of studies about the prognostic and predictive role of family history in prostate cancer, reports the discovered predisposing genes, and biologic and pathologic findings.

RESULTS

mortality from PC remains a significant health care problem, but no trial investigated if it changed in presence of positive family history. The largest family study yet published concluded that men with family history are diagnosed and die at earlier ages than men without it. However, it failed to stress the prognostic value of family history. Genome-wide association studies of prostate cancer have identified a number of genetic variants at different loci in different populations. Prostate neoplasms of patients with positive family history exhibit a different pattern of expression of genes related with estrogen and androgen metabolism within the tumor. High-penetrance and low-penetrance genes in diagnosis and prognosis of prostate cancer, difficulties to define a classification and to quantify relative risks of single genes, documented gene-environment interactions are discussed.

CONCLUSION

family history stands for both shared genetic and environmental factors and their interaction. The availability of prostate-specific antigen test could explain partly the high familial risk, among brothers or shortly after the diagnosis of prostate cancer. Polymorphisms in genes associated with prostate cancer probably represent the most part of familial prostate cancer burden. An increasing knowledge of disregulated cellular pathways of lethal prostate cancer could define which of all genetic alterations have a role in defining new preventive and therapeutic strategies.

Src kinase inhibitors: an emerging therapeutic treatment option for prostate cancer

IMPORTANCE OF THE FIELD

Once prostate cancer becomes castration-resistant, bone metastases are a significant problem and treatment options are limited. As a result, there is a need for more effective therapies that have antitumor and anti-bone metastatic effects. Because Src and Src-family kinases (SFKs) are involved in multiple signaling pathways central to prostate cancer development, progression, and metastasis, in addition to normal and pathologic osteoclast activities, Src inhibition represents a valid therapeutic strategy for investigation.

AREAS COVERED IN THIS REVIEW

Here, current treatment options for advanced prostate cancer, the preclinical rationale behind using Src inhibitors, emerging data from clinical trials of Src inhibitors in prostate cancer, and future therapeutic directions are described. Data published in peer-reviewed journals within the last 20 years or presented at recent European or American Society of Clinical Oncology conferences have been reviewed.

WHAT THE READER WILL GAIN

Readers will gain an insight into the development of therapeutic Src inhibitors, including dasatinib and saracatinib; an understanding of their effects on prostate cancer cells and the bone microenvironment; and emerging clinical data.

TAKE HOME MESSAGE

Src is implicated in prostate cancer progression and metastasis, therefore treatment with Src inhibitors warrants further investigation.

Androgen receptor expression is associated with prostate cancer-specific survival in castrate patients with metastatic disease

OBJECTIVE

To investigate whether baseline (before treatment) clinical variables and tumour specimen characteristics (including the androgen receptor, AR) from patients with castrate-resistant metastatic prostate cancer can be used to predict the time to prostate cancer-specific mortality and overall survival, as AR levels in prostate cancer have been associated with disease progression, including prostate-specific antigen (PSA) recurrence and systemic metastasis.

PATIENTS AND METHODS

Haematoxylin and eosin (H&E) slides/blocks and outcome data from a 104 castrate patients with metastatic disease (43 prostatectomy and 61 prostate needle biopsy samples), were independently reviewed; H&E morphometry and quantitative immunofluorescence were used to assess the samples. Sections were analysed with a multiplex quantitative immunofluorescence (IF) assay for cytokeratin-18 (epithelial cells), 4',6-diamidino-2-phenylindole (nuclei), p63/high molecular weight keratin (basal cells), AR and alpha-methyl CoA-racemase. Images were acquired with spectral imaging software and processed for quantification with IF algorithms.

RESULTS

The median follow-up was 12 years from diagnosis; 49 men (47%) baseline PSA levels of > or = 20 ng/mL, 55 (53%) had a Gleason sum of 8, 63 (60%) died from the disease and 40% were alive (censored). In all, 66 patients had evaluable IF features, and the association with outcome was evaluated by univariate Cox modelling and support-vector regression. PSA was the only clinical variable associated with outcome (concordance index, CoI, 0.41; P < 0.05, log-rank test). The amount of AR present within tumour nuclei (regardless of tissue provenance and primary treatment) significantly correlated with a greater risk of a shorter time to prostate cancer-specific mortality (CoI 0.36; P < 0.05 log-rank test). There were no H&E features that correlated with mortality.

CONCLUSION

By univariate analysis, increased nuclear AR expression in either the diagnostic biopsy and/or radical prostatectomy specimen, from patients with advanced disease, was associated with a reduced time to prostate cancer-specific mortality.