Novel non-AR therapeutic targets in castrate resistant prostate cancer

Castrate resistant prostate cancer (CRPC) remains a disease with significant morbidity and mortality. The recent approval of abiraterone and enzalutamide highlight the improvements which can be made targeting the androgen receptor (AR) axis. Nonetheless, resistance inevitably develops and there is continued interest in targeting alternate pathways which cause disease resistance and progression. Here, we review non-AR targets in CRPC, with an emphasis on novel agents now in development. This includes therapeutics which target the tumour microenvironment, the bone metastatic environment, microtubules, cellular energetics, angiogenesis, the stress response, survival proteins, intracellular signal transduction, DNA damage repair and dendritic cells. Understanding the hallmarks of prostate cancer resistance in CRPC has led to the identification and development of these new targets. We review the molecular rationale, as well at the clinical experience for each of these different classes of agents which are in clinical development.     

Urinary exosome-based androgen receptor-variant 7 detection in metastatic castration-resistant prostate cancer patients

BackgroundAndrogen receptor variant 7 (AR-V7) detection provides important information for the clinical management of abiraterone in metastatic castration-resistant prostate cancer (mCRPC). We performed a non-invasive urine-derived exosomal AR-V7 analysis of mCRPC patients.MethodsA total of 34 mCRPC patients were recruited including 16 patients treated with abiraterone (ABI) with stable prostate-specific antigen (PSA)/radiograph response (the ABI-Sta group) and 18 were resistant to abiraterone (the ABI-Res group). Urine was collected from patients and healthy control patients for the analysis. Exosomal ribonucleic acid was isolated from urine. Urinary exosome-based androgen receptor-variant 7 was detected by quantitative real-time polymerase chain reaction assay. Characteristics of patients and survival data were collected. The correlation between AR-V7 expression and the therapeutic effect/survival outcomes of abiraterone was analyzed.ResultsUrine is the ideal biological sample for exosome separation and AR full-length analysis. Positive urine-derived exosomal AR-V7 was detected in 32.4% (11 of 34) of the mCRPC patients’ urine samples. Positive AR-V7 was more common in the ABI-Res patients than the ABI-Sta patients (50.0% vs. 12.5%, respectively; P=0.009), and was associated with a higher PSA progression rate and poorer overall survival (OS) (P=0.0031, and P=0.0012, respectively).ConclusionsThe present study showed that the detection of urine-derived exosomal AR-V7 provides a sensitive and feasible clinical workflow. The predicting role of urine-derived exosomal AR-V7 in mCRPC patients should be further verified using studies with greater sample sizes.     

Androgen receptor gene mutation,rearrangement, polymorphism

Genetic aberrations of the androgen receptor (AR) caused by mutations, rearrangements, and polymorphisms result in a mutant receptor that has varied functions compared to wild type AR. To date, over 1,000 mutations have been reported in the AR with most of these being associated with androgen insensitivity syndrome (AIS). While mutations of AR associated with prostate cancer occur less often in early stage localized disease, mutations in castration-resistant prostate cancer (CRPC) patients treated with anti-androgens occur more frequently with 10-30% of these patients having some form of mutation in the AR. Resistance to anti-androgen therapy usually results from gain-of-function mutations in the LBD such as is seen with bicalutamide and more recently with enzalutamide (MDV3100). Thus, it is crucial to investigate these new AR mutations arising from drug resistance to anti-androgens and other small molecule pharmacological agents.     

A narrative review of the role of glucocorticoid receptors in prostate cancer: developments in last 5 years

Background and ObjectiveGlucocorticoids, secreted from the adrenal gland, are commonly used in the treatment of castration-resistant prostate cancer (CRPC) because of their anti-inflammatory and anti-toxic effects. However, glucocorticoids have been reported to have the opposite effects within the course of treatment. Many studies have shown that glucocorticoid receptors (GRs) are involved in the establishment of a dominant population of androgen-independent malignant cells, which may result in CRPC. In this review, we summarized the mechanisms of GRs in CRPC and the clinical application of glucocorticoids based on the present evidence.MethodsWe summarized the isoforms of GRs and the mechanisms involved in CRPC. An updated literature search was performed from the ClinicalTrials database, the National Center for Biotechnology Information database and European Union Drug Regulating Authorities Clinical Trials database. The focus was on the timeframe from 2017 to 2022. At least one primary or secondary outcome [prostate-specific antigen (PSA) response rate, progression-free survival (PFS) or overall survival (OS) and median time to PSA progression] according to studies should be included.Key Content and FindingsThe molecular structures and applications of the isoforms of GR have been intensively researched in the past 60 years. In recent years, researchers have pointed out that GRs may be involved in the development of CRPC via genomic and non-genomic effects. Clinical trials in the past 5 years have focused on the efficacy of drugs regarding CRPC. The use of glucocorticoids during treatments of CRPC follows the guidelines (e.g., NCCN Guidelines^®, guidelines of CSCO, etc.). Based on the collected data, prednisone appears to be the most widely used steroid hormone, followed by dexamethasone. Comparisons of the PSA response rate and the median time to PSA progression revealed that the efficacy of the 2 hormones is similar; however, further research on the effect of steroid hormone in CRPC is still required.ConclusionsVarious GR isoforms may play an important part in the development of CRPC, whose mechanism remains unclear. Most clinical trials have focused on the use of prednisone in the last 5 years. The efficacy of prednisone and dexamethasone is similar.     

Management of patients with advanced prostate cancer in Japan: ‘real-world’ consideration of the results from the Advanced Prostate Cancer Consensus Conference

A multidisciplinary approach is necessary to manage advanced prostate cancer. The Advanced Prostate Cancer Consensus Conference (APCCC) in 2019 provided a practical guide to help clinicians consider therapeutic options in controversial areas, but healthcare systems vary across the world. At the 109th annual meeting of the Japanese Urological Association in December 2021, Japanese urologists voted on the questions in the APCCC 2019 guidelines regarding prostate-specific membrane antigen-positron emission tomography (PSMA-PET), management of oligometastatic prostate cancer, management of nonmetastatic castration-resistant prostate cancer (CRPC), management of a primary tumor in metastatic settings, systemic treatment of newly diagnosed metastatic castration-sensitive prostate cancer (CSPC), management of metastatic CRPC (mCRPC), and tumor genomic testing. We summarize the “real-world” status of the management of advanced prostate cancer in Japan. Several differences were noted in the management of advanced prostate cancer between Japanese urologists and the APCCC 2019 guidelines. Many Japanese urologists chose conventional imaging modalities for detecting metastasis instead of PSMA-PET. More Japanese urologists prefer androgen-deprivation therapy (ADT) alone in the management of low-volume metastatic CSPC than the APCCC panelists do, In the management of M0 CRPC, darolutamide and enzalutamide were chosen more by Japanese urologists than by the voters at the APCCC 2019. Bicalutamide remains one of the options for the management of mCRPC in Japan. More Japanese urologists do not recommend microsatellite instability (MSI) and BRCA1/2 tests than the voters at the APCCC 2019. Clinical evidence in Japan should be collected to address these discrepancies     

The role of microRNA in castration-resistant prostate cancer

IntroductionCastration-resistant prostate cancer (CRPC) has a historically low median survival rate, but recent advances and discoveries in microRNAs (miRNAs) have opened the potential for new prognostication modalities to enhance therapeutic success. As new chemotherapies and immunotherapies are developed, there is an increasing need for precision and stratification of CRPC to allow for optimization and personalization of therapy.MethodsA systematic literature review was conducted via electronic database resulting in the selection of 42 articles based on title, abstract, study format, and content by a consensus of all participating authors. Most selected articles were published between 2002 and 2013. In this review, we discuss the robustness of miRNAs as a biomarker platform, miRNAs associated with prostate cancer, and recent discoveries of miRNA associations with CRPC.ResultsThe associations discovered have been of interest owing to the ability to differentiate between CRPC and localized prostate cancer. With the evaluation of multiple miRNAs, it is possible to provide a profile regarding tumor characteristics. Furthermore, actions of miRNAs on CRPC tumor cells have the ability to suppress metastatic phenotypes.ConclusionmiRNAs may have a growing role in CRPC prognostication and may potentially transform into a therapeutic potential.     

Androgens and prostate cancer

Over 60 years ago Huggins and Hodges demonstrated the importance of androgens and prostate cancer. Since then, significant research has revealed that this relationship is multi-faceted and is interwoven with different signaling cascades and protein coactivators. The complex interrelationship between hormone and cancer is best exemplified by the recurrence and progression of prostate cancer after hormonal therapy to a lethally resistant phenotype despite initially encouraging therapeutic responses. If we are to significantly improve survival with novel therapies, further understanding of the emergence of this resistant phenotype is essential. The purpose of this article is to review the mechanisms of androgen action and its relation to hormonal therapy and mechanisms of hormonal resistance.     

The role of mRNA splicing in prostate cancer

Alternative splicing （AS） is a crucial step in gene expression. It is subject to intricate regulation, and its deregulation in cancer can lead to a wide array of neoplastic phenotypes. A large body of evidence implicates splice isoforms in most if not all hallmarks of cancer, including growth, apoptosis, invasion and metastasis, angiogenesis, and metabolism. AS has important clinical implications since it can be manipulated therapeutically to treat cancer and represents a mechanism of resistance to therapy. In prostate cancer （PCa） AS also plays a prominent role and this review will summarize the current knowledge of alternatively spliced genes with important functional consequences. We will highlight accumulating evidence on AS of the components of the two critical pathways in PCa： androgen receptor （AR） and phosphoinositide 3-kinase （PI3K）. These observations together with data on dysregulation of splice factors in PCa suggest that AR and PI3K pathways may be interconnected with previously unappreciated splicing regulatory networks. In addition, we will discuss several lines of evidence implicating splicing regulation in the development of the castration resistance.     

6种microRNAs在前列腺癌组织中的表达

目的:研究表明miRNAs在人类恶性肿瘤的发生发展过程中起着重要作用,本研究检测6种miRNAs:miR-98、let-7d、let-7g、miR-96、miR-182及miR-183在前列腺癌组织中的表达情况及其临床意义。方法:采用原位分子杂交方法,结合组织芯片技术分别检测38例BPH和52例前列腺癌中6种miRNAs的表达情况。并对前列腺癌组织中6种miRNA与Gleason评分,临床分期及6种miRNA间进行相关分析。结果:6种miRNAs中,与BPH组织相比,在前列腺癌组织中表达降低的为miR-98、let-7d、let-7g;而表达升高的为miR-96、miR-182及miR-183,差异均有统计学意义(P<0.05)。6种miRNAs的表达与前列腺癌的Gleason评分均相关(P<0.05),但与患者的年龄及血清PSA水平均无明显相关性(P>0.05)。其中miR-96和miR-182的表达与前列腺癌的临床分期均有相关性(P<0.05),miR-98和miR-96的表达均与肿瘤累及前列腺的叶数存在相关性(P<0.05)。另外,前列腺癌组织中,miR-96、miR-182及miR-183的表达彼此之间呈正相关(P<0.01,r分别为0.41,0.44),let-7d与let-7g的表达之间呈正相关(P<0.01,r=0.46),miR-98与let-7d及let-7g的表达之间呈正相关(P<0.05,r分别为0.31,0.34)。结论:miR-98、let-7d、let-7g、miR-96、miR-182及miR-183构成的miRNA表达谱在一定程度上反映了前列腺癌的生物学行为,可能作为前列腺癌早期诊断和预后评估的重要生物标记物。     

去势抵抗性前列腺癌新型内分泌治疗耐药机制研究进展

前列腺癌是男性泌尿生殖系统最常见的恶性肿瘤之一,雄激素在其发生发展中都扮演着重要角色。经去势治疗(ADT)后绝大多数前列腺癌都会进展成为去势抵抗性前列腺癌(CRPC)。肾上腺来源的雄激素和(或)雄激素受体(AR)的改变(包括AR基因扩增)驱动了瘤内雄激素的合成,进而重新雄激素轴信号通路。目前,阿比特龙、恩扎鲁胺等抗雄激素治疗药物都是CRPC患者的一线治疗用药。但是,治疗一段时间后患者仍然会出现耐药和疾病进展。因此,明确CRPC患者抗雄激素治疗耐药机制可以为克服CRPC治疗耐药和改善CRPC患者的预后提供契机。