Castration-resistant Prostate Cancer Stage Research Articles

Investigating High-risk Factors, Precise Diagnosis, and Treatment of Castration- Resistant Prostate Cancer (CRPC).

The treatment of metastatic castration-resistant prostate cancer (mCRPC) in the actual world currently presents difficulties. In light of this, it is crucial to investigate high-risk factors for the progression of advanced prostate cancer and to identify methods for delaying the onset of CRPC. This study aimed to explore the high-risk factors that impact the progression of prostate cancer and emphasize the significance of precise diagnosis and treatment based on etiological classification in the clinical management of castration-resistant prostate cancer. A retrospective analysis was conducted on 277 newly diagnosed cases of PCa treated with endocrine therapy. A follow-up was done on prostate-specific antigen (PSA) levels and testosterone. Additionally, a prospective analysis was performed on the clinical data of 60 patients with CRPC. Following the principle of "4W1H", 30 patients were included in the precision treatment group for a second biopsy and related tests, while another 30 patients were included in the conventional treatment group. The therapeutic effect and prognosis of the two groups were observed. Distant metastasis (HR = 1.879, 95% CI: 1.311 ~ 2.694, P = 0.001), PSA nadir > 0.2 ng/mL (HR = 1.843, 95% CI: 1.338 ~ 2.540, P = 0.001), testosterone nadir > 20 ng/dL (HR = 1.403, 95% CI: 1.035 ~ 1.904, P = 0.029), and time to testosterone nadir > 6 months (HR = 1.919, 95% CI: 1.364 ~ 2.701, P = 0.001) were risk factors for the progression to CRPC. Patients in the CRPC group were treated with precision therapy and conventional therapy based on their molecular subtyping. The precision treatment group showed a significantly prolonged median PSA progression-free survival compared to the conventional treatment group (16.0 months vs. 13.0 months, P=0.025). The median radiographic progression-free survival was also significantly extended in the precision treatment group compared to the conventional treatment group (21.0 months vs. 16.0 months, P=0.042). Patients with prostate cancer diagnosed with distant metastasis at initial presentation require early intervention. Close monitoring of PSA and serum testosterone changes is necessary during the process of endocrine therapy. After entering the CRPC stage, the etiological classification precision treatment can improve the therapeutic effect and improve the prognosis of patients.

Lost opportunities: the underutilization of castrate-resistant prostate cancer treatment in real-world settings.

Various treatment regimens are now available for metastatic castrate-resistant prostate cancer (CRPC). This work evaluates the real-world prescription patterns of CRPC in a large tertiary care center and the factors influencing them. Health records of 330 patients with de novo metastatic hormone-sensitive prostate cancer (HSPC), treated and progressed to CRPC between 2016 and 2020, were reviewed from a prospective uro-oncological database. We studied their demographics, medical co-morbidities, treatment utilization patterns before and after progression to CRPC, and survival outcomes. The median age was 74 years [interquartile range (IQR), 67-80 years] at diagnosis of CRPC. At CRPC, beyond androgen deprivation therapy (ADT) monotherapy, 70.3% (n=232) of patients received at least one additional line, 21.5% (n=71) received two lines, and 5.5% (n=18) received three lines of systemic treatments. As first-line treatment, novel hormonal agents (NHAs) were the most prescribed at 57.6% (n=190). The likelihood of receiving treatment was associated with age <65 years [odds ratio (OR) 2.08, P=0.01, 95% confidence interval (CI): 1.22-3.57] and lower Charlson Comorbidity Index (CCI) score (OR: 2.62, P=0.04, 95% CI: 1.07-6.45), treatment intensification for HSPC (OR 2.45, P=0.04, 95% CI: 1.07-5.62) and primary physician being an oncologist (OR 1.59, P=0.04, 95% CI: 1.04-2.48). Patients who received additional treatment lines at CRPC had longer survival (median: 23 vs. 17 months, OR 1.72, P<0.01, 95% CI: 1.23-2.38). More than one in four patients do not receive any additional treatment line beyond ADT monotherapy and have worse survival outcomes. Health status, prescribing physician, and treatment at HSPC appear to affect prescription patterns at the CRPC stage.

Racial Differences in Androgen Receptor (AR) and AR Splice Variants (AR-SVs) Expression in Treatment-Naïve Androgen-Dependent Prostate Cancer.

Androgen receptor splice variants (AR-SVs) contribute to the aggressive growth of castration-resistant prostate cancer (CRPC). AR-SVs, including AR-V7, are expressed in ~30% of CRPC, but minimally in treatment-naïve primary prostate cancer (PCa). Compared to Caucasian American (CA) men, African American (AA) men are more likely to be diagnosed with aggressive/potentially lethal PCa and have shorter disease-free survival. Expression of a truncated AR in an aggressively growing patient-derived xenograft developed with a primary PCa specimen from an AA patient led us to hypothesize that the expression of AR-SVs could be an indicator of aggressive growth both in PCa progression and at the CRPC stage in AA men. Tissue microarrays (TMAs) were created from formalin-fixed paraffin-embedded (FFPE) prostatectomy tumor blocks from 118 AA and 115 CA treatment-naïve PCa patients. TMAs were stained with AR-V7-speicifc antibody and with antibodies binding to the N-terminus domain (NTD) and ligand-binding domain (LBD) of the AR. Since over 20 AR-SVs have been identified, and most AR-SVs do not as yet have a specific antibody, we considered a 2.0-fold or greater difference in the NTD vs. LBD staining as indication of potential AR-SV expression. Two AA, but no CA, patient tumors stained positively for AR-V7. AR staining with NTD and LBD antibodies was robust in most patients, with 21% of patients staining at least 2-fold more for NTD than LBD, indicating that AR-SVs other than AR-V7 are expressed in primary treatment-naïve PCa. About 24% of the patients were AR-negative, and race differences in AR expression were not statistically significant. These results indicate that AR-SVs are not restricted to CRPC, but also are expressed in primary PCa at higher rate than previously reported. Future investigation of the relative expression of NTD vs. LBD AR-SVs could guide the use of newly developed treatments targeting the NTD earlier in the treatment paradigm.

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

The androgen receptor (AR) plays an essential role in prostate cancer progression and is a key target for prostate cancer treatment. However, patients with prostate cancer undergoing androgen deprivation therapy eventually experience biochemical relapse, with hormone-sensitive prostate cancer progressing into castration-resistant prostate cancer (CRPC). The widespread application of secondary antiandrogens, such as enzalutamide, indicates that targeting AR remains the most efficient method for CRPC treatment. Unfortunately, neither can block AR signaling thoroughly, leading to AR reactivation within several months. Here, we report an approach for suppressing reactivated AR signaling in the CRPC stage. A combination of the protein phosphatase 1 subunit α (PP1α)-specific inhibitor tautomycin and enzalutamide synergistically inhibited cell proliferation and AR signaling in LNCaP and C4-2 cells, as well as in AR variant-positive 22RV1 cells. Our results revealed that enzalutamide competed with residual androgens in CRPC, enhancing tautomycin-mediated AR degradation. In addition, the remaining competitive inhibitory role of enzalutamide on AR facilitated tautomycin-induced AR degradation in 22RV1 cells, further decreasing ARv7 levels via a full-length AR/ARv7 interaction. Taken together, our findings suggest that the combination of tautomycin and enzalutamide could achieve a more comprehensive inhibition of AR signaling in CRPC. AR degraders combined with AR antagonists may represent a new therapeutic strategy for CRPC.

Chronologically modified androgen receptor in recurrent castration-resistant prostate cancer and its therapeutic targeting.

Resistance to second-generation androgen receptor (AR) antagonists such as enzalutamide is an inevitable consequence in patients with castration-resistant prostate cancer (CRPC). There are no effective therapeutic options for this recurrent disease. The expression of truncated AR variant 7 (AR-V7) has been suggested to be one mechanism of resistance; however, its low frequency in patients with CRPC does not explain the almost universal acquisition of resistance. We noted that the ability of AR to translocate to nucleus in an enzalutamide-rich environment opens up the possibility of a posttranslational modification in AR that is refractory to enzalutamide binding. Chemical proteomics in enzalutamide-resistant CRPC cells revealed acetylation at Lys609 in the zinc finger DNA binding domain of AR (acK609-AR) that not only allowed AR translocation but also galvanized a distinct global transcription program, conferring enzalutamide insensitivity. Mechanistically, acK609-AR was recruited to the AR and ACK1/TNK2 enhancers, up-regulating their transcription. ACK1 kinase-mediated AR Y267 phosphorylation was a prerequisite for AR K609 acetylation, which spawned positive feedback loops at both the transcriptional and posttranslational level that regenerated and sustained high AR and ACK1 expression. Consistent with these findings, oral and subcutaneous treatment with ACK1 small-molecule inhibitor, (R)-9b, not only curbed AR Y267 phosphorylation and subsequent K609 acetylation but also compromised enzalutamide-resistant CRPC xenograft tumor growth in mice. Overall, these data uncover chronological modification events in AR that allows prostate cancer to evolve through progressive stages to reach the resilient recurrent CRPC stage, opening up a therapeutic vulnerability.

Long noncoding RNA GAS5 interacts and suppresses androgen receptor activity in prostate cancer cells.

The androgen receptor (AR) plays an important role in the progression of prostate cancer and is the most important therapeutic target. However, androgen deprivation therapy will finally lead patients to progress to castration-resistant prostate cancer (CRPC). Here, we confirmed that GAS5, a long noncoding RNA, could interact and suppress AR transactivation in CRPC C4-2 cells. Knockdown GAS5 by short hairpin RNA would enhance the transcription of AR via promote AR recruitment to the promoter of its downstream target genes. Functionally, GAS5 overexpression inhibits cell proliferation partially through inhibiting AR transactivation in C4-2 cells. Moreover, knocking down GAS5 protects C4-2 cells from the docetaxel-induced cell apoptosis. In return, the suppressed AR was found to downregulate the GAS5 expression, which forms a feedback loop resulted in AR high transcription activity in CRPC. Collectively, our findings revealed the important role of GAS5 in AR axis activity regulation and CRPC progression. Targeting GAS5 to intervene the feedback loop might be a new potential therapeutic approach for the patients at CRPC stage.

Neuroendocrine differentiation in metastatic breast cancer following CDK 4/6 inhibitors.

e13029 Background: First-line treatment with a CDK4/6 inhibitor in combination with an aromatase inhibitor for HR+/HER2- postmenopausal metastatic breast cancer (mBC) is considered as a standard of care based on the compelling data across all landmark trials. Methods: We report our experience about two cases with metastatic breast cancer treated by CDK4/6 inhibitor in combination with an aromatase inhibitor, which develop neuroendocrine differentiation. After observing an unusual massive progression, a biopsy of the metastasis was performed in both patients. Both histological analysis confirmed a lobular breast cancer with small cell neuroendocrine features and a high proliferation index (KI 67 90%). An NGS (Next generation sequencing) profile was realized on primary and metastatic tumors to detect new acquired genomic alterations. Results: The comparative analysis of the NGS results of primary and metastatic tumors revealed the occurrence of several events in both patients under treatment. For one patient, we identified new mutations in the genes CDH1, FANCG, PIK3CA, PTEN and TP53, which did not exist initially. For the second patient, we found an amplification of the segment containing FGFR1, CCND1, FGF4, FGF3, FADD genes and the deletion of the segment containing RB1 andTP53 genes. Such events were not observed on the primary tumor. Conclusions: Prostate adenocarcinoma may develop neuroendocrine features in later stages of castration-resistant prostate cancer but neuroendocrine differentiation is atypical in breast carcinoma. In case of unusual rapidly progressive disease after CDK4/6 inhibitor, biopsy of new metastases should be recommanded to search neuroendocrine differentiation, or druggable mutations to guide the treatment.

MED12 Mutations Promote Castration Resistant Prostate Cancer Through Hyper‐activated SHH Signaling

Prostate cancer is the most common malignancy and the second leading cause of cancer associated deaths among US men. As an androgen-driven disease, prostate cancer is critically dependent upon androgen receptor (AR) signaling. Accordingly, most prostate cancer patients respond very well to androgen deprivation therapy. The current problem lies with the fact that nearly all patients progress to a lethal form of the disease after androgen deprivation therapy known as castration resistant prostate cancer (CRPC). Once patients reach the stage of CRPC, treatment options are frustratingly limited and average survival times range from two to three years only. Thus, there is a compelling need to develop effective treatments for patients suffering from CRPC. Sonic hedgehog (SHH) signaling is a stromal-epithelial interacting pathway that is critical for prostate development and cell growth. SHH signaling is induced by androgen deprivation thereby leading to re-activation of AR target genes to promote prostate cancer cell growth in the absence of androgens. Furthermore, AR interacts with GLI proteins, downstream effectors in the SHH pathway. Therefore, GLI3-dependent SHH signaling in androgen deprived cells could promote re-activation of AR target genes and consequently lead to CRPC. It is currently unknown how GLI3-dependent SHH signaling is induced in CRPC. Several studies have found that MED12, a subunit of Mediator, is commonly mutated in prostate cancer and, interestingly, MED12 has been shown to play a critical role in restricting GLI3-dependent SHH signaling. We therefore hypothesize that MED12 mutations promote GLI3-dependent SHH signaling in prostate cancer to drive progression towards CRPC. We generated stable MED12 knockdown cells, which likely recapitulates a MED12 mutant setting, followed by proliferation and qPCR assays in androgen replete and androgen deprived conditions to test our hypothesis. Our results show that MED12 knockdown promotes prostate cancer growth specifically in an androgen deprived setting and that this hyper-active growth is dependent upon GLI3. Furthermore, we also show that GLI3 target genes are sharply upregulated when MED12 expression is low and androgens are absent. The collective results of our study therefore indicate that prostate cancer patients with MED12 mutations could relapse to CRPC after androgen deprivation therapy by hyperactivating the GLI3 dependent SHH signaling pathway. Importantly, our results thus suggest that therapeutic agents that target the SHH signaling pathway could prove to be beneficial for MED12 mutant prostate cancer patients.

Abstract 1836: ONC201 shows synergistic effect with the androgen receptor AR-inhibitor darotulamide in prostate cancer models

Abstract Prostate cancer (PC) is the most frequently diagnosed cancer among men in the United States and is the 3rd cause of cancer mortality. Despite advances in the treatment and understanding of pathogenesis, patients with metastatic PC invariably progress to a lethal stage of castration-resistant prostate cancer (CRPC). Inhibition of androgen signaling remains crucial for the treatment of CRPC, but novel treatment strategies are urgently needed. ONC201 is a first-in-class, selective inhibitor of dopamine receptor D2 that upregulates death-receptor 5 and induces apoptosis. ONC201 induced apoptosis in PC cell lines and showed synergy with enzalutamide, docetaxel and everolimus (Lev A Mol Cancer Res 2018). Darolutamide (DARO) is a novel androgen receptor (AR) antagonist approved for treatment of patients with non-metastatic CRPC. DARO has higher affinity to AR and preclinical activity against enzalutamide-resistant PC cell lines including AR variants associated with enzalutamide agonism (Borgmann H Eur Urol 2018). We treated human PC cell lines (LNCAP [castration sensitive, AR wild-type], 22Rv1 [castration-resistant cell line that expresses AR splice variant AR-V7], DU145 [AR negative], PC3 [AR negative]) with DARO alone and combined with ONC201. Single-agent DARO decreased PC cell viability in Cell-Titer-Glo assays (IC50s of 10 and 693 nM for LNCAP and DU145, respectively). ONC201 showed strong synergism with DARO in LNCAP cells (combination indices &amp;lt; 1 at concentrations of 156, 312, 625 nM, and 1.25 µM of DARO with 2.5 μM ONC201). ONC201 induced robust apoptosis in 22Rv1 as measured by PARP cleavage, which was partially amplified by DARO. PARP cleavage was also observed in LNCAP cells with less intensity and not potentiated by DARO. ONC201 reduced the expression of phospho-AR (p-AR) in both 22Rv1 and LNCAP. The combination of ONC201 and DARO had a significant additive effect in reducing p-AR in 22Rv1, but not in LNCAP. ONC201 reduced PSA protein levels in LNCAP cells while DARO alone did not cause any significant change in PSA. Immunofluorescence experiments showed that DARO caused significant reduction of AR nuclear translocation in both 22rV1 and LNCAP cells. The combination with ONC201 potentiated this inhibition of AR translocation in both cell lines. ONC201 showed strong antiproliferative activity against PC cells lines independent of AR status. Combination of ONC201 with DARO demonstrated synergy in enzalutamide resistant 22Rv1 cells expressing AR-V7 with marked reduction of nuclear localization of AR. Our studies provide preclinical rationale for combination of ONC201 with DARO as a novel therapy of PC. Citation Format: Fabio Tavora, Lanlan Zhou, Ali Amin, Safran Howard, Navaraj Arunasalam, Andre de Souza, Anthony Mega, Dragan Golijanin, Wafik El-Deiry, Benedito Carneiro. ONC201 shows synergistic effect with the androgen receptor AR-inhibitor darotulamide in prostate cancer models [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1836.

Survival in men diagnosed with castration resistant prostate cancer: A population-based observational study in Sweden.

e16555 Background: Data focusing on the castration resistant phase of prostate cancer (PC) outside clinical trial settings are scarce. This study aims to investigate PC-specific and overall survival (OS) in men with castration resistant prostate cancer (CRPC) on a population level. Methods: The STHLM-0 cohort (n = 400 000) with data on all prostate specific antigen (PSA) values and prostate biopsies taken in Stockholm, Sweden, from 2003 to 2015 were linked to other population registries. All men with a PC diagnosis and rising PSA after three months consecutive use of gonadotropin-releasing hormone or surgical castration were defined as CRPC (n = 1712). Kaplan-Meier was used to estimate median time-to-event and 95% confidence intervals (CI). Patients were stratified by metastasis status at PC diagnosis and multivariable Cox regression was used to adjust for clinical subgroups, including Gleason, age, T stage and calendar period (2006-2011 vs 2012-2015). Results: Metastasis at PC diagnosis was associated with shorter OS from castration resistance. From CRPC onset the median OS was 22.8 months (95% CI 21.2-25.5) and 13.1 (95% CI 11.5-14.2) months for patients without and with metastasis at PC diagnosis, respectively. The median PC-specific survival from CRPC was 30.7 (95% CI 27.9-34.7) months and 13.5 (95% CI 12.3-16.1) months for patients without and with metastasis at PC diagnosis, respectively. For patients with metastasis at PC diagnosis, factors influencing OS from CRPC were; entering CRPC stage in the later vs earlier calendar period (HR 0.61 95% CI 0.48-0.78, p &lt; 0.001), age &gt; 80 vs &lt; 70 (HR 1.46, 95% CI 1.05-2.02, p &lt; 0.02), T4 vs T1 stage (HR 1.56, 95% CI:1.02-2.37, p &lt; 004). For patients without metastasis at PC diagnosis, developing CRPC in the later vs the earlier calendar period was associated with superior survival from CRPC (HR 0.78 95% CI 0.65-0.92, p &lt; 0.004). Conclusions: Metastasis at PC diagnosis was associated with worse survival outcomes in CRPC patients. Individuals who became castration resistant in the later calendar period survived longer compared to those in the same stage in the earlier calendar period, most likely due to the introduction of novel agents for CRPC patients and more accurate staging methods.

Abstract 1918: Patient-derived hormone-naive prostate cancer xenograft models reveal GRB10 as an AR-repressed gene driving the development of castration-resistant prostate cancer

Abstract Prostate cancer is the most commonly diagnosed noncutaneous cancer and the leading cause of cancer-related death in North American men. Although androgen-deprivation therapy is initially effective in controlling the growth of hormone-naive prostate cancers (HNPC) in patients, currently incurable castration-resistant prostate cancer (CRPC) inevitably develops. Thus, we aim to identify CRPC driver genes that may provide new targets to enhance CRPC therapy. In this study, patient-derived xenografts (PDXs) of HNPCs that develop CRPC following host castration were examined for changes in expression of genes at various time points after castration using transcriptome profiling analysis; particular attention was given to pre-CRPC changes in expression indicative of genes acting as potential CRPC drivers. Eighty genes were found to be significantly upregulated at the CRPC stage while 7 of them also showed elevated expression prior to CRPC development. Among the latter, Growth Factor Receptor Bound Protein 10 (GRB10) was the most significantly and consistently upregulated gene. Moreover, we found GRB10 expression was elevated in clinical CRPC compared to HNPC in several clinical cohorts. Further investigation suggests that GRB10 is transcriptionally regulated by androgen receptor through an androgen-responsive element located in GRB10's intron. Functionally, we found that GRB10 knockdown markedly reduced prostate cancer cell proliferation and activity of AKT, a well-established CRPC mediator. Also, a positive correlation between AKT activity and GRB10 expression was found in clinical cohorts. In conclusion, GRB10 acts as a driver of CRPC and sensitizes AR pathway inhibitors, and hence GRB10-targeting provides a novel therapeutic strategy for the disease. Citation Format: Jun Hao, Xinpei Ci, Hui Xue, Rebecca Wu, Xin Dong, Fang Zhang, Sifeng Qu, Fan Zhang, Anne M. Haegert, Peter W. Gout, Colin Collins, Martin E. Gleave, Dong Lin, Yuzhuo Wang. Patient-derived hormone-naive prostate cancer xenograft models reveal GRB10 as an AR-repressed gene driving the development of castration-resistant prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1918.

Neuroendocrine Differentiation in Prostate Cancer: Emerging Biology, Models, and Therapies.

Although a de novo clinical presentation of small cell neuroendocrine carcinoma of the prostate is rare, a subset of patients previously diagnosed with prostate adenocarcinoma may develop neuroendocrine features in later stages of castration-resistant prostate cancer (CRPC) progression as a result of treatment resistance. Despite sharing clinical, histologic, and some molecular features with other neuroendocrine carcinomas, including small cell lung cancer, castration-resistant neuroendocrine prostate cancer (CRPC-NE) is clonally derived from prostate adenocarcinoma. CRPC-NE therefore retains early prostate cancer genomic alterations and acquires new molecular changes making them resistant to traditional CRPC therapies. This review focuses on recent advances in our understanding of CRPC-NE biology, the transdifferentiation/plasticity process, and development and characterization of relevant CRPC-NE preclinical models.

Patient-derived Hormone-naive Prostate Cancer Xenograft Models Reveal Growth Factor Receptor Bound Protein 10 as an Androgen Receptor-repressed Gene Driving the Development of Castration-resistant Prostate Cancer

BackgroundAlthough androgen deprivation therapy is initially effective in controlling growth of hormone-naive prostate cancers (HNPCs) in patients, currently incurable castration-resistant prostate cancer (CRPC) inevitably develops. ObjectiveTo identify CRPC driver genes that may provide new targets to enhance CRPC therapy. Design, setting, and participantsPatient-derived xenografts (PDXs) of HNPCs that develop CRPC following host castration were examined for changes in expression of genes at various time points after castration using transcriptome profiling analysis; particular attention was given to pre-CRPC changes in expression indicative of genes acting as potential CRPC drivers. Outcome measurements and statistical analysisThe functionality of a potential CRPC driver was validated via its knockdown in cultured prostate cancer cells; its clinical relevance was established using data from prostate cancer patient databases. Results and limitationsEighty genes were found to be significantly upregulated at the CRPC stage, while seven of them also showed elevated expression prior to CRPC development. Among the latter, growth factor receptor bound protein 10 (GRB10) was the most significantly and consistently upregulated gene. Moreover, elevated GRB10 expression in clinical prostate cancer samples correlated with more aggressive tumor types and poorer patient treatment outcome. GRB10 knockdown markedly reduced prostate cancer cell proliferation and activity of AKT, a well-established CRPC mediator. A positive correlation between AKT activity and GRB10 expression was also found in clinical cohorts. ConclusionsGRB10 acts as a driver of CRPC and sensitizes androgen receptor pathway inhibitors, and hence GRB10 targeting provides a novel therapeutic strategy for the disease. Patient summaryDevelopment of castration-resistant prostate cancer (CRPC) is a major problem in the management of the disease. Using state-of-the-art patient-derived hormone-naive prostate cancer xenograft models, we found and validated the growth factor receptor bound protein 10 gene as a driver of CRPC, indicating that it may be used as a new molecular target to enhance current CRPC therapy.

Androgen receptor mediated epigenetic regulation of CRISP3 promoter in prostate cancer cells

Cysteine-rich secretory protein 3 (CRISP3) is one of the most upregulated genes in prostate cancer. Androgen receptor (AR) plays an important role not only in initial stages of prostate cancer development but also in the advanced stage of castration-resistant prostate cancer (CRPC). Role of AR in regulation of CRISP3 expression is not yet known. In order to understand the regulation of CRISP3 expression, various overlapping fragments of CRISP3 promoter were cloned in pGL3 luciferase reporter vector. All constructs were transiently and stably transfected in PC3 (CRISP3 negative) and LNCaP (CRISP3 positive) cell lines and promoter activity was measured by luciferase assay. Promoter activity of LNCaP stable clones was significantly higher than PC3 stable clones. Further in CRISP3 negative PC3 and RWPE-1 cells, CRISP3 promoter was shown to be silenced by histone deacetylation. Treatment of LNCaP cells with DHT resulted in increase in levels of CRISP3 transcript and protein. AR dependency of CRISP3 promoter was also evaluated in LNCaP stable clones by luciferase assay. To provide molecular evidence of epigenetic regulation of CRISP3 promoter and its response to DHT, ChIP PCR was performed in PC3 and LNCaP cells. Our results demonstrate that CRISP3 expression in prostate cancer cells is androgen dependent and in AR positive cells, CRISP3 promoter is epigenetically regulated by AR.

Multicenter prospective study of switching from GnRH agonists to GnRH antagonist for patients with early stage of castration resistant prostate cancer as a second-line hormonal therapy.

183 Background: It was reported that GnRH antagonist could extend progression free survival for prostate cancer patients significantly longer than GnRH agonist in a first line hormonal therapy. However, the usefulness of switching from GnRH agonist to GnRH antagonist as a second hormonal therapy remains obscure. We performed a multicentral prospective study to investigate whether the switching from GnRH agonist to GnRH antagonist (degalerix) for patients with castration resistant prostate cancer (CRPC) as the 2nd line hormonal therapy was effective. Methods: 37 patients who were pathologically diagnosed as prostatic adenocarcinoma and developed CRPC after 1st line hormonal therapy with GnRH agonist plus anti-androgens were enrolled. After confirming anti-androgen withdrawal syndrome, they were treated with switching from GnRH agonists to degalerix. The primary endpoint was PSA response (PSA decline or up to 10% over baseline PSA). Secondary endpoints were the time to 25% PSA increase from the baseline (PSA response time), PSA progression free survival (PPFS), the time to treatment failure, cancer specific survival, radiographic PFS (rPFS), and safety. Results: Mean age was 76 years old, super high risk; 20 cases (54.1%), high risk; 11 cases (29.7%), intermediate risk; 5 cases (13.5%), low risk; one case (2.7%). PSA responder rate was 24.3% (9 cases). In responders, the median PSA response time was 5.75 months, the median PPFS was 1.77 months, and rPFS rate at 3 months was 96%. Regarding safety, only 2 cases (5.4%) showed G3 of AE. The PSA response had no relationship with the change of serum testosterone, LH nor FSH. Conclusions: The effectiveness of switching from GnRH agonist to GnRH antagonist showed to be limited. Although no predictive factor of the switching was recognized, some long-term responders were seen. We expect the possibility of switching to GnRH antagonist for patients in the early stage of CRPC, especially non-metastatic status. Clinical trial information: UNKNOWN.

Prognostic impact of DNA repair germline variants in hormone sensitive prostate cancer stage.

262 Background: Inherited and somatic aberrations in DNA repair genes in castrate resistant prostate cancer (CRPC) are associated with poor prognosis, but respond well to poly ADP ribose polymerase (PARP) inhibitors. We evaluated the prevalence and prognostic impact of harboring germline DNA repair variants in hormone sensitive prostate cancer (HSPC). Methods: Germline DNA from buffy coat was sequenced on HiSeq4000 with a median coverage of 200X for DNA repair variants in 20 genes in HSPC and CRPC patients (pts) enrolled in a hospital registry. Pts were divided into two groups; Group A: pts enrolled at the time of CRPC stage; Group B: treatment naïve HSPC stage pts. The primary endpoints were to determine any impact of harboring DNA repair variants on time to progression from HSPC to CRPC and, from CRPC to death. Group A pts were retrospectively analyzed for time to progression from HSPC to CRPC while Group B patients were followed prospectively for outcomes. Statistical analysis included Cox proportional hazard models and Wilcoxon Rank sum test with significance at p≤0.05. Results: In Group A, 51/562 CRPC pts (9.07%) had variants in the 20 genes (most frequently in BRCA2; n = 15). 44/51 pts with variants and 399/511 without variants had died. Median time of progression from HSPC to CRPC with/without variants was 22.1 vs. 25.1 months (mths); p-value = 0.679. Median time from CRPC to death with/without variants was 32.2 Vs. 27.7 mths (p = 0.6). In HSPC Group B, 14/100 pts were identified with germline variants in ATM (n = 5), CHEK2 (n = 3), BRCA1 (n = 2), BRCA2 (n = 2), RAD50 (n = 1), and MSH2 (n = 1). 31/100 have died and median time to progression from HSPC to CRPC with/without variants was 15.6 vs.11.8 mths, p-value = 0.76. Conclusions: Pts with germline DNA repair variants detected in HSPC stage were not associated with poor prognosis. Presence of additional somatic DNA repair gene aberrations in cell-free DNA, not investigated in this cohort may add to the prevalence of DNA repair gene variations in HSPC and together impact prognosis adversely so as to provide a rationale for PARP inhibitor therapy in select HSPC stage pts.

Bone and calcium metabolism associated with malignancy. Treatment of radium-223 dichloride for bone metastasis in castration resistant prostate cancer patients.

In patients with castration resistant prostate cancer(CRPC), the most frequent site of metastases is bone particularly with osteoblastic change, which accounts for 90% at the late stage of CRPC and is accompanied by symptomatic skeletal symptoms(SSEs)such as bone pain or pathological fractures. Radium-223(Ra-223)dichloride emits α particles and has been proven to improve overall survival(OS)and QOL by reducing SSEs in metastatic CRPC patients. Although hemotoxic adverse events(AEs)of Ra-223 treatment including anemia, neutropenia and thrombocytopenia, and non-hemotoxic AEs including nausea, diarrhea and bone pain have been reported, they were mild and well tolerated. The completion of 6 injections of Ra-223 is important for prolonging OS. The optimal time of Ra-223 administration is recommended the duration when PSA is increasing regardless of abiraterone or enzalutamide treatment prior to chemotherapy.

Reactivation of androgen receptor-regulated lipid biosynthesis drives the progression of castration-resistant prostate cancer

Androgen receptor (AR) is a transcriptional activator that, in prostate cells, stimulates gene expression required for various cellular functions, including metabolisms and proliferation. AR signaling is also essential for the development of hormone-dependent prostate cancer (PCa) and its activity can be blocked by androgen-deprivation therapies (ADTs). Although PCa patients initially respond well to ADTs, the cancer inevitably relapses and progresses to lethal castration-resistant prostate cancer (CRPC). Although AR activity is generally restored in CRPC despite the castrate level of androgens, it is unclear whether AR signaling is significantly reprogrammed. In this study, we examined the AR cistrome in a PCa cell line-derived CRPC model using integrated bioinformatical analyses. Significantly, we found that the AR cistrome is largely retained in the CRPC stage. In particular, AR-mediated lipid biosynthesis is highly conserved and reactivated during the progression to CRPC, and increased level of lipid synthesis is associated with poor prognosis. The restoration of lipid biosynthetic pathways is partially due to the increased expression of AR splice variants. Blocking lipid/cholesterol synthesis in AR variants-expressing CRPC cell line and xenograft models markedly reduces tumor growth through inhibition of mTOR pathway. Silencing the expression of a fatty acid elongase, ELOVL7, also leads to the regression of CRPC xenograft tumors. These results demonstrate the importance of reactivation of AR-regulated lipid biosynthetic pathways in driving CRPC progression, and suggest that ADTs may be therapeutically enhanced by blocking lipid biosynthetic pathways.

Morphologic Variants of Epithelial and Neuroendocrine Tumors of the Prostate. The Pathologist's Point of View

Abstract More than 95% of all carcinomas of the prostate are referred to as acinar, microacinar, usual, or conventional type. A minority have been classified as variants. Variants can vary in histologic appearance and divergent differentiation compared with usual acinar adenocarcinoma. Some variants constitute different types of carcinoma and are not adenocarcinomas. Variants that represent a challenge to diagnose include the deceptively benign-looking atrophic, pseudohyperplastic, microcystic, and foamy gland variants. The signet ring-like, pleomorphic giant cell, and sarcomatoid variants have worse prognosis than usual acinar adenocarcinoma. Some variants can occur after therapy, such endocrine and radiation therapy: squamous neoplasms, neuroendocrine tumors, sarcomatoid carcinoma (ie, carcinosarcoma), and pleomorphic giant cell variant. Neuroendocrine prostate cancer is an aggressive variant of prostate cancer that often arises in later stages of castration-resistant prostate cancer.

The association of JAK2 polymorphisms with prognosis in castration-resistant prostate cancer (CRPC).

313 Background: We evaluated variation in candidate genes implicated in either initiation or progression of prostate cancer with survival in CRPC stage. Methods: Germline DNA was extracted from peripheral blood mononuclear cells of CRPC patients enrolled in a clinically annotated registry. Fourteen candidate genes were tagged using single nucleotide polymorphisms (SNPs) from HapMap with minor allele frequency of &gt; 5%. The primary endpoint was overall survival (OS), defined as time from development of CRPC to death. Principal component analysis was used for gene levels tests of significance. For SNP level results the per allele hazard ratios (HR) and 95% confidence intervals (CI) under the additive allele model using Cox regression adjusted for age at CRCP and Gleason score (GS) were used. Results: Two hundred and forty five CRPC patients who met the criteria of having adequate DNA were genotyped (14 genes, 84 SNPs). The median age of the cohort was 69 years (range 43-93). The GS distribution was 55% with GS≥8, 32% with GS = 7 and 13% with GS &lt; 7 or unknown. Median time from castration resistance to death for the cohort was 2.67 years (IQ range: 1.6-4.07, 144 deaths). At the gene level JAK2 was detected to be associated with OS. Six of 18 JAK2 SNPs were associated with OS after adjustment for age and GS as well as pruning of SNPs in high linkage disequilibrium with each other (see table). In our multivariate model including age, GS, rs2149556, and rs4372063, the adjusted HRs for rs2149556 and rs4372063 were 0.67 (95% CI 0.38-1.18) and 2.17 (95% CI 1.25-3.76), respectively. The protective effect of rs2149556 appears after adjusting for the presence of minor alleles for rs4372063 in this dataset. Conclusions: Germline variation in the JAK2gene is associated with survival in CRPC stage and warrants further validation as a potential prognostic biomarker. [Table: see text]