Castration-resistant metastatic prostate cancer: current status and treatment possibilities

The prognostic role of pan-immune inflammation value in patients with metastatic castration resistance prostate cancer treated with Lutetium-177 (177Lu)-PSMA-617

BACKGROUND

Pan-immune inflammation value (PIV) is a newly defined biomarker that includes whole cellular components that are indicators of systemic inflammation in complete blood count (CBC), easily accessible and has the potential to reflect both the body's immune response and systemic inflammation status. This study evaluated the pretreatment PIV for its prognostic impact on overall survival (OS) in patients with metastatic castration-resistant prostate cancer (mCRPC) treated with Lutetium-177 (177Lu)-PSMA-617.

METHODS

The PIV was based on the earliest CBC obtained within 1 month before treatment initiation. Patients were categorized into low and high PIV groups based on the median pretreatment PIV, and the relationship between OS and PIV groups was assessed by multivariable analysis.

RESULTS

A total of 43 patients with mCRPC treated with (177Lu)-PSMA-617 were included. The median OS was longer in the low PIV group (15.1 months [95% confidence interval [CI] 10.6-19.5]) than in the high PIV group (4.2 months [95% CI 1.7-6.6]) (p < 0.001). In multivariable analysis, high PIV (hazard ratio [HR]: 4.3, 95% CI 1.194-15.93, p = 0.026) and high Eastern Cooperative Oncology Group performance score (HR: 7.05, 95% CI 1.48-33.46, p = 0.014) were associated with shorter OS.

CONCLUSION

This study showed that pretreatment PIV might be a prognostic factor in patients with mCRPC treated with (177Lu)-PSMA-617.

The Evolving Role of 18F-FDG PET/CT in Diagnosis and Prognosis Prediction in Progressive Prostate Cancer

Positron emission tomography/computed tomography (PET/CT) is widely used in prostate cancer to evaluate the localized tumor burden and detect symptomatic metastatic lesions early. ¹⁸F-FDG is the most used tracer for oncologic imaging, but it has limitations in detecting early-stage prostate cancer. ⁶⁸Ga-PSMA is a new tracer that has high specificity and sensibility in detecting local and metastatic tumors. But with the progression of prostate cancer, the enhancement of glucose metabolism in progressive prostate cancer provides a chance for ¹⁸F-FDG. This review focuses on PET/CT in the detection and prognosis of prostate cancer, summarizing the literature on ¹⁸F-FDG and ⁶⁸Ga-PSMA in prostate cancer and highlighting that ¹⁸F-FDG has advantages in detecting local recurrence, visceral and lymph node metastases compared to ⁶⁸Ga-PSMA in partial progressive prostate cancer and castration-resistant prostate cancer patients. We emphasize ¹⁸F-FDG PET/CT can compensate for the weakness of ⁶⁸Ga-PSMA PET/CT in progressive prostate cancer.

Nanoparticles for Targeting of Prostate Cancer

Prostate cancer (PCa) is the leading cause of death by cancer in men. Because of the drastic decline in the survival rate of PCa patients with advanced/metastatic disease, early diagnosis of disease and therapy without toxic side effects is crucial. Chemotherapy is widely used to control the progression of PCa at the later stages; however, it is associated with off-target toxicities and severe adverse effects due to the lack of specificity. Delivery of therapeutic or diagnostic agents by using targeted nanoparticles is a promising strategy to enhance accuracy and sensitivity of diagnosis of PCa and to increase efficacy and specificity of therapeutic agents. Numerous efforts have been made in past decades to create nanoparticles with different architectural bases for specific delivery payloads to prostate tumors. Major PCa associated cell membrane protein markers identified as targets for such purposes include folate receptor, sigma receptors, transferrin receptor, gastrin-releasing peptide receptor, urokinase plasminogen activator receptor, and prostate specific membrane antigen. Among these markers, prostate specific membrane antigen has emerged as an extremely specific and sensitive targetable marker for designing targeted nanoparticle-based delivery systems for PCa. In this article, we review contemporary advances in design, specificity, and efficacy of nanoparticles functionalized against PCa. Whenever feasible, both diagnostic as well as therapeutic applications are discussed.

Screening of Drug Repositioning Candidates for Castration Resistant Prostate Cancer

Purpose: Most prostate cancers (PCs) initially respond to androgen deprivation therapy (ADT), but eventually many PC patients develop castration resistant PC (CRPC). Currently, available drugs that have been approved for the treatment of CRPC patients are limited. Computational drug repositioning methods using public databases represent a promising and efficient tool for discovering new uses for existing drugs. The purpose of the present study is to predict drug candidates that can treat CRPC using a computational method that integrates publicly available gene expression data of tumors from CRPC patients, drug-induced gene expression data and drug response activity data. Methods: Gene expression data from tumoral and normal or benign prostate tissue samples in CRPC patients were downloaded from the Gene Expression Omnibus (GEO) and differentially expressed genes (DEGs) in CRPC were determined with a meta-signature analysis by a metaDE R package. Additionally, drug activity data were downloaded from the ChEMBL database. Furthermore, the drug-induced gene expression data were downloaded from the LINCS database. The reversal relationship between the CRPC and drug gene expression signatures as the Reverse Gene Expression Scores (RGES) were computed. Drug candidates to treat CRPC were predicted using summarized scores (sRGES). Additionally, synergic effects of drug combinations were predicted with a Target Inhibition interaction using the Minimization and Maximization Averaging (TIMMA) algorithm. Results: The drug candidates of sorafenib, olaparib, elesclomol, tanespimycin, and ponatinib were predicted to be active for the treatment of CRPC. Meanwhile, CRPC-related genes, in this case MYL9, E2F2, APOE, and ZFP36, were identified as having gene expression data that can be reversed by these drugs. Additionally, lenalidomide in combination with pazopanib was predicted to be most potent for CRPC. Conclusion: These findings support the use of a computational reversal gene expression approach to identify new drug and drug combination candidates that can be used to treat CRPC.

miR-221-5p regulates proliferation and migration in human prostate cancer cells and reduces tumor growth in vivo

Background

Despite latest advances in prostate cancer (PCa) therapy, PCa remains the third-leading cause of cancer-related death in European men. Dysregulation of microRNAs (miRNAs), small non-coding RNA molecules with gene expression regulatory function, has been reported in all types of epithelial and haematological cancers. In particular, miR-221-5p alterations have been reported in PCa.

Methods

miRNA expression data was retrieved from a comprehensive publicly available dataset of 218 PCa patients (GSE21036) and miR-221-5p expression levels were analysed. The functional role of miR-221-5p was characterised in androgen- dependent and androgen- independent PCa cell line models (C4–2 and PC-3M-Pro4 cells) by miR-221-5p overexpression and knock-down experiments. The metastatic potential of highly aggressive PC-3M-Pro4 cells overexpressing miR-221-5p was determined by studying extravasation in a zebrafish model. Finally, the effect of miR-221-5p overexpression on the growth of PC-3M-Pro4luc2 cells in vivo was studied by orthotopic implantation in male Balb/cByJ nude mice and assessment of tumor growth.

Results

Analysis of microRNA expression dataset for human primary and metastatic PCa samples and control normal adjacent benign prostate revealed miR-221-5p to be significantly downregulated in PCa compared to normal prostate tissue and in metastasis compared to primary PCa. Our in vitro data suggest that miR-221-5p overexpression reduced PCa cell proliferation and colony formation. Furthermore, miR-221-5p overexpression dramatically reduced migration of PCa cells, which was associated with differential expression of selected EMT markers. The functional changes of miR-221-5p overexpression were reversible by the loss of miR-221-5p levels, indicating that the tumor suppressive effects were specific to miR-221-5p. Additionally, miR-221-5p overexpression significantly reduced PC-3M-Pro4 cell extravasation and metastasis formation in a zebrafish model and decreased tumor burden in an orthotopic mouse model of PCa.

Conclusions

Together these data strongly support a tumor suppressive role of miR-221-5p in the context of PCa and its potential as therapeutic target.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5819-6) contains supplementary material, which is available to authorized users.

Clinical response to radium-223 dichloride in men with metastatic castrate-resistant prostate cancer

PURPOSE/OBJECTIVE

Radium-223 prolongs survival and decreases symptomatic skeletal events in men with metastatic castrate-resistant prostate cancer and is indicated in patients with painful bone metastases. However, pain responses are rarely reported and often asked about by patients. Further, patients and their physicians are concerned about a lack of pain response portending a poor treatment response and may be inclined to change systemic therapies before completing 6 cycles. We evaluated the likelihood and time course of pain response, potential predictors of response, and its prognostic value in patients receiving radium-223.

MATERIALS AND METHODS

We reviewed the charts of patients who received radium-223 in our department. All patients were planned for 6 cycles with a prescribed dose of 50-55 kBq/kg at each administration. Pain scores, subjective response to pain, analgesic use, treatment toxicities, and laboratory values were recorded at each visit. Symptomatic skeletal events and survival were also recorded.

RESULTS

48 patients received at least one cycle of radium-223 and 27 (56%) received all 6 planned cycles. Median survival from first treatment was 16.0 months (95% CI 8.9 to 19.2 months). 33% experienced at least one symptomatic skeletal event during or after treatment. 62.5% of men reported a decrease in pain from pre-treatment baseline. Of men with improved pain, 96% experienced an improvement before the third cycle. Pain relief was not associated with a decrease in ALK-P or PSA or improved survival.

CONCLUSIONS

Approximately two-thirds of patients who undergo treatment with radium-223 will experience an improvement in pain and, if it occurs, it will most likely occur within the first two cycles. Patients should be counseled about this timeline and, if pain improvement isn't achieved, palliative radiation and oral analgesic readjustment should be considered. Pain response is not associated with survival and should not be used to evaluate the effectiveness of treatment.

Treatment of Metastatic Prostate Cancer in Older Adults

The aging of the population, along with rising life expectancy, means that increasing numbers of older men will be diagnosed with prostate cancer, and a large proportion of these men will present with metastatic disease. In this paper, we discuss recent advances in prostate cancer treatment. In particular, we review management approaches for older patients with metastatic prostate cancer based on the decision tree developed by the International Society of Geriatric Oncology, which categorized older men as "fit," "vulnerable," and "frail" according to comprehensive geriatric assessment.

Platycodin D induces tumor growth arrest by activating FOXO3a expression in prostate cancer in vitro and in vivo

Platycodin D (PD), a major saponin derived from Platycodin grandiflorum, exerted cytotoxicity against prostate cancer cell lines (PC3, DU145 and LNCaP cells) with IC₅₀ values in the range of 11.17 to 26.13μmol/L, whereas RWPE-1cells (a non-malignant human prostate epithelial cell line) were not significantly affected. A further study in these cell lines showed that PD could potently affect cell proliferation (indicated by the bromodeoxyuridine assay), induce cell apoptosis (determined by Annexin V-FITC flow cytometry) and cause cell cycle arrest (indicated by PI staining). After being treated with PD for 48 hours, DU145 and LNCaP cells were arrested in the G0 /G1 phase, and PC3 cells were arrested in the G2/M phase. A Western blotting analysis indicated that PD increased the expression of the FOXO3a transcription factor, decreased the expression of p-FOXO3a and MDM2 and increased the expression of FOXO-responsive genes, p21 and p27. MDM2 silencing (transiently by siRNA-MDM2) increased the PD-induced FOXO3a protein expression, while MDM2 overexpression (in cells transiently transfected with a pcDNA3-MDM2 plasmid) decreased the PD-induced expression of the FOXO3a protein. Moreover, PD dose-dependently inhibited the growth of PC3 xenograft tumors in BALB/c nude mice. A Western blotting analysis of the excised xenograft tumors indicated that similar changes in protein expression also occurred in vivo. These results suggest that PD exhibits significant activity against prostate cancer in vitro and in vivo. The FOXO3a transcription factor appears to be involved in the activity of PD. Together, all of these findings provide a basis for the future development of this agent for human prostate cancer therapy.

Radium-223 dichloride: a review of its use in patients with castration-resistant prostate cancer with symptomatic bone metastases

Radium-223 dichloride (Xofigo®; formerly Alpharadin™) [hereafter referred to as radium-223] is a first-in-class alpha particle-emitting radiopharmaceutical that has recently been approved for the treatment of patients with castration-resistant prostate cancer (CRPC) with symptomatic bone metastases and no known visceral metastatic disease. Radium-223 is a calcium mimetic, which targets bone, delivering cytotoxic radiation to the sites of bone metastases. In the recently reported Alpharadin™ in Symptomatic Prostate Cancer (ALSYMPCA) phase III study, radium-223 was associated with significantly improved overall survival compared with placebo, making it the first bone-targeted CRPC therapy for which an overall survival benefit has been demonstrated. The ALSYMPCA study also demonstrated the beneficial effects of radium-223 on disease-related symptomatic skeletal events, pain and health-related quality of life. Radium-223 was generally well tolerated, being associated with low rates of myelosuppression and generally mild gastrointestinal adverse events. Thus, radium-223 is a valuable addition to the treatment options for this poor-prognosis population.

Targeting the relaxin hormonal pathway in prostate cancer

Targeting the androgen signalling pathway has long been the hallmark of anti-hormonal therapy for prostate cancer. However, development of androgen-independent prostate cancer is an inevitable outcome to therapies targeting this pathway, in part, owing to the shift from cancer dependence on androgen signalling for growth in favor of augmentation of other cellular pathways that provide proliferation-, survival- and angiogenesis-promoting signals. This review focuses on the role of the hormone relaxin in the development and progression of prostate cancer, prior to and after the onset of androgen independence, as well as its role in cancers of other reproductive tissues. As the body of literature expands, examining relaxin expression in cancerous tissues and its role in a growing number of in vitro and in vivo cancer models, our understanding of the important involvement of this hormone in cancer biology is becoming clearer. Specifically, the pleiotropic functions of relaxin affecting cell growth, angiogenesis, blood flow, cell migration and extracellular matrix remodeling are examined in the context of cancer progression. The interactions and intercepts of the intracellular signalling pathways of relaxin with the androgen pathway are explored in the context of progression of castration-resistant and androgen-independent prostate cancers. We provide an overview of current anti-hormonal therapeutic treatment options for prostate cancer and delve into therapeutic approaches and development of agents aimed at specifically antagonizing relaxin signalling to curb tumor growth. We also discuss the rationale and challenges utilizing such agents as novel anti-hormonals in the clinic, and their potential to supplement current therapeutic modalities.

Relaxin receptor antagonist AT-001 synergizes with docetaxel in androgen-independent prostate xenografts

Androgen hormones and the androgen receptor (AR) pathway are the main targets of anti-hormonal therapies for prostate cancer. However, resistance inevitably develops to treatments aimed at the AR pathway resulting in androgen-independent or hormone-refractory prostate cancer (HRPC). Therefore, there is a significant unmet need for new, non-androgen anti-hormonal strategies for the management of prostate cancer. We demonstrate that a relaxin hormone receptor antagonist, AT-001, an analog of human H2 relaxin, represents a first-in-class anti-hormonal candidate treatment designed to significantly curtail the growth of androgen-independent human prostate tumor xenografts. Chemically synthesized AT-001, administered subcutaneously, suppressed PC3 xenograft growth by up to 60%. AT-001 also synergized with docetaxel, standard first-line chemotherapy for HRPC, to suppress tumor growth by more than 98% in PC3 xenografts via a mechanism involving the downregulation of hypoxia-inducible factor 1 alpha and the hypoxia-induced response. Our data support developing AT-001 for clinical use as an anti-relaxin hormonal therapy for advanced prostate cancer.

EpCAM expression in the prostate cancer makes the difference in the response to growth factors

INTRODUCTION

Epithelial cell adhesion molecule (EpCAM) is expressed in tumors with an epithelial cell of origin, in a heterogeneous manner. Prostate cancer stem-like cells highly express EpCAM. However, little is known about how EpCAM is involved in the ability of cells to adapt to micro-environmental changes in available growth factors, which is one of the essential biological phenotypes of cancer stem-like cells (CSCs).

METHODS

EpCAM-high and EpCAM-low subpopulations of cells were established from the prostate cancer cell line PC-3. Signal transductions in response to serum starvation, and on the exposure to EGF ligand or the specific inhibitor were analyzed in terms. Furthermore, we analyzed the expression level of amino acid transporters which contribute to the activation of mTOR signal between the two subgroups.

RESULTS

EpCAM-high and EpCAM-low PC-3 subpopulations showed markedly different responses to serum starvation. EpCAM expression was positively correlated with activation of the mTOR and epithelial growth factor receptor (EGFR) signaling pathways. Furthermore, AMP-activated protein kinase (AMPK) was gradually de-activated in EpCAM-low PC-3 cells in the absence of serum.

CONCLUSIONS

EpCAM regulates the AMPK signaling pathway, essential for the response to growth factors characterized by EGF. LAT1, the amino acid transporter stabilized at the cellular membrane by EpCAM, is likely to be responsible for the difference in the susceptibility to EGF between EpCAM-high and EpCAM-low PC-3 cells.

Inhibition of stromal PlGF suppresses the growth of prostate cancer xenografts

The growth and vascularization of prostate cancer is dependent on interactions between cancer cells and supporting stromal cells. The primary stromal cell type found in prostate tumors is the carcinoma-associated fibroblast, which produces placental growth factor (PlGF). PlGF is a member of the vascular endothelial growth factor (VEGF) family of angiogenic molecules and PlGF mRNA levels increase after androgen deprivation therapy in prostate cancer. In this study, we show that PlGF has a direct dose-dependent proliferative effect on human PC-3 prostate cancer cells in vitro and fibroblast-derived PlGF increases PC-3 proliferation in co-culture. In xenograft tumor models, intratumoral administration of murine PlGF siRNA reduced stromal-derived PlGF expression, reduced tumor burden and decreased the number of Ki-67 positive proliferating cells associated with reduced vascular density. These data show that targeting stromal PlGF expression may represent a therapeutic target for the treatment of prostate cancer.

Sonoporation by low-frequency and low-power ultrasound enhances chemotherapeutic efficacy in prostate cancer cells in vitro

Combination therapy is used to optimize anticancer efficacy and reduce the toxicity and side-effects of drugs upon systemic administration. Ultrasound (US) combined with micro-bubbles (UM) enhances the intracellular uptake of cytotoxic drugs by tumor cells, particularly drug-resistant cells. In the present study, low-frequency and low-energy US (US irradiation conditions: frequency, 21 kHz; power density, 0.113 W/cm²; exposure time, 2 min at a duty cycle of 70%; and valid treatment time, 84 sec) were used in combination with microbubbles (100 μl/ml) to deliver mitoxantrone HCl (MIT) to DU145 cells. The results showed that UM did not change the cell viability in the short- or long-term. However, UM statistically enhanced the therapeutic effects and up to 31.26±3.34% of the cells exposed to UM were permeabilized compared with 9.74±2.55% of cells in the control, when using calcein (MW, 622.53) as a fluorogenic marker. Notably, UM affected the migration capability of the DU145 cells at 6 h post-treatment. In conclusion, the ultrasonic parameters used in the present study enhanced the chemotherapeutic effect and reduced the unwanted side-effects of MIT.