Advances in the management of castration resistant prostate cancer

An insight into the diagnostic, prognostic, and taxanes resistance of double zinc finger and homeodomain factor's expression in naïve prostate cancer

Currently, clinical biomarkers are urgently needed to improve patient management to guide personal therapy for cancer. In this study, we investigate the deregulation of Zeb-1 in prostate cancer (PC) Tunisian patients. Expression patterns of the Zeb-1 were investigated in prostate adenocarcinoma and benign prostate biopsies using quantitative real-time reverse transcription-polymerase chain reaction (RT-qPCR) and 2-ΔΔCt method. Statistical analysis was used to identify differences across groups depending on gene expression level. Furthermore, we exploited a follow-up over 15 years to correlate Zeb-1 deregulation and clinical outcomes in PC patients. Based on ROC curve analyses, the AUC was found in discriminating PC patients from controls (AUC = 0.757; p < 0.001). In addition, the higher expression level was significantly associated with PSA, Digital Rectal Examination, Gleason score, tumor stage, and distant lymph node metastases. Moreover, Zeb-1 overexpression was correlated with shorter overall survival (OS) (p = 0.042), poor progression-free survival (PFS) (p = 0.007), and with resistance to taxanes (p = 0.012). Our data provide the aberrant expression of Zeb-1 in PC patients suggesting its potential diagnostic, prognostic, and theranostic role. Further functional studies are mandatory to strengthen these results and to uncover the molecular mechanism of this neoplasm.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-024-03941-8.

Racial disparity in the utilization of immunotherapy for advanced prostate cancer

PURPOSE

To identify whether there was a disparity in the utilization of immunotherapy in the treatment of black patients with metastatic castration resistant prostate cancer (mCRPC).

METHODS

Using the National Cancer Database, we identified patients between 2010- 2015 with likely minimally/asymptomatic mCRPC. We analyzed annual trends for chemotherapy and immunotherapy use and compared utilization by demographic and clinical features. Multivariable analysis was performed to determine predictors of receiving immunotherapy vs chemotherapy.

RESULTS

We identified 1301 patients with likely mCRPC. The majority were non Hispanic White (NHW - 63 %) and 23 % were non-Hispanic Black (NHB). Overall, there was increased utilization of immunotherapy in mCRPC from 2010 onwards, with the peak occurring in 2014 (4.6 %). Chemotherapy use increased significantly, peaking in 2014 to 26.1 %. However, the increased utilization of immunotherapy in the mCRPC was mainly seen in White patients: from 50 % to 74.2 % of the cohort. Conversely, there was a decrease in utilization of immunotherapy among Black mCPRC patients: from 50 % to 25.8 %. On multivariable analysis, there was no statistically significant difference between treatment types by race.

CONCLUSION

FDA approval of Sipuleucel-T for mCRPC led to increased utilization of immunotherapy shortly thereafter, but this was mainly noted in white patients. Black patients comparatively did not exhibit increased utilization of this novel agent after 2010. Further studies are necessary to help understand barriers to access to new treatment in mCRPC and eliminate the burden of disease in minority populations."

The key cellular senescence related molecule RRM2 regulates prostate cancer progression and resistance to docetaxel treatment

BACKGROUND

Prostate cancer is a leading cause of cancer-related deaths among men worldwide. Docetaxel chemotherapy has proven effective in improving overall survival in patients with castration-resistant prostate cancer (CRPC), but drug resistance remains a considerable clinical challenge.

METHODS

We explored the role of Ribonucleotide reductase subunit M2 (RRM2), a gene associated with senescence, in the sensitivity of prostate cancer to docetaxel. We evaluated the RRM2 expression, docetaxel resistance, and ANXA1 expression in prostate cancer cell lines and tumour xenografts models. In addition, We assessed the impact of RRM2 knockdown, ANXA1 over-expression, and PI3K/AKT pathway inhibition on the sensitivity of prostate cancer cells to docetaxel. Furthermore, we assessed the sensitivity of prostate cancer cells to the combination treatment of COH29 and docetaxel.

RESULTS

Our results demonstrated a positive association between RRM2 expression and docetaxel resistance in prostate cancer cell lines and tumor xenograft models. Knockdown of RRM2 increased the sensitivity of prostate cancer cells to docetaxel, suggesting its role in mediating resistance. Furthermore, we observed that RRM2 stabilizes the expression of ANXA1, which in turn activates the PI3K/AKT pathway and contributes to docetaxel resistance. Importantly, we found that the combination treatment of COH29 and docetaxel resulted in a synergistic effect, further augmenting the sensitivity of prostate cancer cells to docetaxel.

CONCLUSION

Our findings suggest that RRM2 regulates docetaxel resistance in prostate cancer by stabilizing ANXA1-mediated activation of the PI3K/AKT pathway. Targeting RRM2 or ANXA1 may offer a promising therapeutic strategy to overcome docetaxel resistance in prostate cancer.

An Aminosteroid Derivative Shows Higher In Vitro and In Vivo Potencies than Gold Standard Drugs in Androgen-Dependent Prostate Cancer Models

The aminosteroid derivative RM-581 blocks with high potency the growth of androgen-dependent (AR⁺) prostate cancer VCaP, 22Rv1, and LAPC-4 cells. Notably, RM-581 demonstrated superior antiproliferative activity in LAPC-4 cells compared to enzalutamide and abiraterone, two drugs that exhibited a synergistic effect in combination with RM-581. These findings suggest that RM-581 may have an action that is not directly associated with the hormonal pathway of androgens. Furthermore, RM-581 completely blocks tumor growth in LAPC-4 xenografts when given orally at 3, 10, and 30 mg/kg in non-castrated (intact) nude mice. During this study, an accumulation of RM-581 was observed in tumors compared to plasma (3.3-10 folds). Additionally, the level of fatty acids (FA) increased in the tumors and livers of mice treated with RM-581 but not in plasma. The increase was greater in unsaturated FA (21-28%) than in saturated FA (7-11%). The most affected FA were saturated palmitic acid (+16%), monounsaturated oleic acid (+34%), and di-unsaturated linoleic acid (+56%), i.e., the 3 most abundant FA, with a total of 55% of the 56 FA measured. For cholesterol levels, there was no significant difference in the tumor, liver, or plasma of mice treated or not with RM-581. Another important result was the innocuity of RM-581 in mice during a 28-day xenograft experiment and a 7-week dose-escalation study, suggesting a favorable safety window for this new promising drug candidate when given orally.

Sexual health and treatment-related sexual dysfunction in sexual and gender minorities with prostate cancer

Prostate cancer treatment has substantial effects on sexual health and function. Sexual function is a vital aspect of human health and a critical component of cancer survivorship, and understanding the potential effects of different treatment modalities on sexual health is crucial. Existing research has extensively described the effects of treatment on male erectile tissues necessary for heterosexual intercourse; however, evidence regarding their effects on sexual health and function in sexual and gender minority populations is minimal. These groups include sexual minority - gay and bisexual - men, and transgender women or trans feminine people in general. Such unique effects in these groups might include altered sexual function in relation to receptive anal and neovaginal intercourse and changes to patients' role-in-sex. Sexual dysfunctions following prostate cancer treatment affecting quality of life in sexual minority men include climacturia, anejaculation, decreased penile length, erectile dysfunction, and problematic receptive anal intercourse, including anodyspareunia and altered pleasurable sensation. Notably, clinical trials investigating sexual outcomes after prostate cancer treatment do not collect sexual orientation and gender identity demographic data or outcomes specific to members of these populations, which perpetuates the uncertainty regarding optimal management. Providing clinicians with a solid evidence base is essential to communicate recommendations and tailor interventions for sexual and gender minority patients with prostate cancer.

Human embryonic stem cells exert antitumor effects on prostate cancer cells in a co-culture microenvironment

Prostate cancer is currently the most common malignancy among men. Given the limitations of current conventional anticancer therapies, new high-risk treatments are urgently needed. Previous studies have shown that embryonic stem cells (ESCs) can reverse the tumorigenic phenotype of tumor cells. However, there are still challenges in using human ESCs (hESCs) directly in cancer treatment. To facilitate the practical application of hESCs, we established a co-culture system consisting of prostate cancer cell lines and hESCs and investigated the antitumor activity of the supernatant of the co-culture system (Co-Sp) in vitro and in vivo, as well as the underlying mechanisms involved. The Co-Sp decreased the viability of prostate cancer cells in a concentration-dependent manner, significantly inhibited colony formation, and induced cell cycle arrest at the G0/G1 phase of the cell cycle. In addition, Co-Sp promoted apoptosis of prostate cancer cells and inhibited cell migration and invasion. In vivo studies also revealed that Co-Sp inhibited tumor growth in the xenograft model. Mechanistic studies showed that Co-Sp reduced the expression of cyclin D1, cyclin E, CDK4, CDK2, MMP-9, MMP-1, and Bcl-2, and increased the expression of p21, cleaved caspase-9, cleaved caspase-3, cleaved PARP, and Bax in prostate cancer cells. Furthermore, the Co-Sp decreased the phosphorylation of PI3K, AKT, and mTOR in cells and tumor tissues. Taken together, our results indicated that the Co-Sp has potent antitumor activity and could directly inhibit tumor growth. Our findings provide a new and effective way for the application of hESCs in cancer therapy and contribute to a new strategy for clinical stem cell therapy.

Trigred motif 36 regulates neuroendocrine differentiation of prostate cancer via HK2 ubiquitination and GPx4 deficiency

Neuroendocrine prostate cancer (NEPC), the most lethal subtype of castration-resistant prostate cancer (PCa), may evolve from the neuroendocrine differentiation (NED) of PCa cells. However, the molecular mechanism that triggers NED is unknown. Trigred motif 36 (TRIM36), a member of the TRIM protein family, exhibits oncogenic or anti-oncogenic roles in various cancers. We have previously reported that TRIM36 is highly expressed to inhibit the invasion and proliferation of PCa. In the present study, we first found that TRIM36 was lowly expressed in NEPC and its overexpression suppressed the NED of PCa. Next, based on proteomic analysis, we found that TRIM36 inhibited the glycolysis pathway through suppressing hexokinase 2 (HK2), a crucial glycolytic enzyme catalyzing the conversion of glucose to glucose-6-phosphate. TRIM36 specifically bound to HK2 through lysine 48 (lys48)-mediated ubiquitination of HK2. Moreover, TRIM36-mediated ubiquitination degradation of HK2 downregulated the level of glutathione peroxidase 4 (GPx4), a process that contributed to ferroptosis. In conclusion, TRIM36 can inhibit glycolysis via lys48-mediated HK2 ubiquitination to reduce GPX4 expression and activate ferroptosis, thereby inhibiting the NED in PCa. Targeting TRIM36 might be a promising approach to retard NED and treat NEPC.

Cancer-Associated Fibroblast Heterogeneity, Activation and Function: Implications for Prostate Cancer

The continuous remodeling of the tumor microenvironment (TME) during prostate tumorigenesis is emerging as a critical event that facilitates cancer growth, progression and drug-resistance. Recent advances have identified extensive communication networks that enable tumor-stroma cross-talk, and emphasized the functional importance of diverse, heterogeneous stromal fibroblast populations during malignant growth. Cancer-associated fibroblasts (CAFs) are a vital component of the TME, which mediate key oncogenic events including angiogenesis, immunosuppression, metastatic progression and therapeutic resistance, thus presenting an attractive therapeutic target. Nevertheless, how fibroblast heterogeneity, recruitment, cell-of-origin and differential functions contribute to prostate cancer remains to be fully delineated. Developing our molecular understanding of these processes is fundamental to developing new therapies and biomarkers that can ultimately improve clinical outcomes. In this review, we explore the current challenges surrounding fibroblast identification, discuss new mechanistic insights into fibroblast functions during normal prostate tissue homeostasis and tumorigenesis, and illustrate the diverse nature of fibroblast recruitment and CAF generation. We also highlight the promise of CAF-targeted therapies for the treatment of prostate cancer.

Complexities of Prostate Cancer

Prostate cancer has a long disease history and a wide variety and uncertainty in individual patients' clinical progress. In recent years, we have seen a revolutionary advance in both prostate cancer patient care and in the research field. The power of deep sequencing has provided cistromic and transcriptomic knowledge of prostate cancer that has not discovered before. Our understanding of prostate cancer biology, from bedside and molecular imaging techniques, has also been greatly advanced. It is important that our current theragnostic schemes, including our diagnostic modalities, therapeutic responses, and the drugs available to target non-AR signaling should be improved. This review article discusses the current progress in the understanding of prostate cancer biology and the recent advances in diagnostic and therapeutic strategies.

High dose androgen suppresses natural killer cytotoxicity of castration-resistant prostate cancer cells via altering AR/circFKBP5/miRNA-513a-5p/PD-L1 signals

Most advanced prostate cancer (PCa) patients initially respond well to androgen deprivation therapy, but almost all eventually develop castration-resistant prostate cancer (CRPC). Early studies indicated the bipolar androgen therapy via a cycling of high dose and low dose of androgen to suppress PCa growth might be effective in a select patient population. The detailed mechanisms, however, remain unclear. Here we found the capacity of natural killer (NK) cells to suppress the CRPC cells could be suppressed by a high dose of dihydrotestosterone (DHT). Mechanism dissection indicates that transactivated AR can increase circularRNA-FKBP5 (circFKBP5) expression, which could sponge/inhibit miR-513a-5p that suppresses the PD-L1 expression via direct binding to its 3'UTR to negatively impact immune surveillance from NK cells. Preclinical data from in vitro cell lines and an in vivo mouse model indicate that targeting PD-L1 with sh-RNA or anti-PD-L1 antibody can enhance the high dose DHT effect to better suppress CRPC cell growth. These findings may help us to develop novel therapies via combination of high dose androgen with PD-1/PD-L1 checkpoint inhibitors to better suppress CRPC progression.

Developing New Treatment Options for Castration-Resistant Prostate Cancer and Recurrent Disease

Prostate cancer (PCa) is a major diagnosed cancer among men globally, and about 20% of patients develop metastatic prostate cancer (mPCa) in the initial diagnosis. PCa is a typical androgen-dependent disease; thus, hormonal therapy is commonly used as a standard care for mPCa by inhibiting androgen receptor (AR) activities, or androgen metabolism. Inevitably, almost all PCa will acquire resistance and become castration-resistant PCa (CRPC) that is associated with AR gene mutations or amplification, the presence of AR variants, loss of AR expression toward neuroendocrine phenotype, or other hormonal receptors. Treating CRPC poses a great challenge to clinicians. Research efforts in the last decade have come up with several new anti-androgen agents to prolong overall survival of CRPC patients. In addition, many potential targeting agents have been at the stage of being able to translate many preclinical discoveries into clinical practices. At this juncture, it is important to highlight the emerging strategies including small-molecule inhibitors to AR variants, DNA repair enzymes, cell survival pathway, neuroendocrine differentiation pathway, radiotherapy, CRPC-specific theranostics and immune therapy that are underway or have recently been completed.

hsa_circ_0092339 acts as a molecular sponge in castration-resistant prostate cancer via the hsa-mir-940/C-MYC axis

Aims: We aimed to determine whether intronic circRNA acts as a molecular sponge in castration-resistant prostate cancer (CRPC). Materials & methods: A gene chip technique was used to conduct sequencing. A qPCR experiment was performed to verify the result. Radioimmunoprecipitation, RNA pull-down and dual-luciferase reporter assays were performed to particularly expound its function. Verification of downstream effects was carried out through qPCR and western blot, and a xenograft assay was performed in vivo for verification. Results: Intronic circRNA hsa_circ_0092339 in the nucleus was highly expressed in CRPC cell lines. hsa_circ_0092339 did not regulate the expression of its parental gene. hsa_circ_0092339 functions like a molecular sponge, preventing degradation of C-MYC mRNA by absorbing hsa-mir-940. Conclusion: hsa_circ_0092339 plays a critical role in CRPC through targeting C-MYC indirectly by absorbing hsa-mir-940.

Real-world experience of abiraterone acetate plus prednisone in chemotherapy-naive patients with metastatic castration-resistant prostate cancer: long-term results of the prospective ABItude study

Background

Limited real-world data exist on the effectiveness and safety of abiraterone acetate plus prednisone (abiraterone hereafter) in the treatment of patients with metastatic castration-resistant prostate cancer (mCRPC) naive to chemotherapy. Most of the few available studies had a retrospective design and included a small number of patients. In the interim analysis of the ABItude study, abiraterone showed good clinical effectiveness and safety profile in the chemotherapy-naive setting over a median follow-up of 18 months.

Patients and methods

We evaluated clinical and patient-reported outcomes (PROs) of chemotherapy-naive mCRPC patients treated with abiraterone as for clinical practice in the Italian, observational, prospective, multicentric ABItude study. mCRPC patients were enrolled at abiraterone start (February 2016-June 2017) and followed up for 3 years; clinical endpoints and PROs, including quality of life (QoL) and pain, were prospectively collected. Kaplan–Meier curves were estimated.

Results

Of the 481 patients enrolled, 454 were assessable for final study analyses. At abiraterone start, the median age was 77 years, with 58.6% elderly patients and 69% having at least one comorbidity (57.5% cardiovascular diseases). Visceral metastases were present in 8.4% of patients. Over a median follow-up of 24.8 months, median progression-free survival (any progression reported by the investigators), time to abiraterone discontinuation, and overall survival were, respectively, 17.3 months [95% confidence interval (CI) 14.1-19.4 months], 16.0 months (95% CI 13.1-18.2 months), and 37.3 months (95% CI 36.5 months-not estimable); 64.2% of patients achieved ≥50% reduction in prostate-specific antigen. QoL assessed by Functional Assessment of Cancer Therapy—Prostate, the European Quality of Life 5 Dimensions 3 Level, and European Quality of Life Visual Analog Scale remained stable during treatment. Median time to pain progression according to Brief Pain Inventory data was 31.1 months (95% CI 24.8 months-not estimable). Sixty-two patients (13.1%) had at least one adverse drug reaction (ADR) and 8 (1.7%) one serious ADR.

Conclusion

With longer follow-up, abiraterone therapy remains safe, well tolerated, and active in a large unselected population.

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A prospective real-life study of abiraterone acetate in mCRPC patients.

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In 481 chemotherapy-naive mCRPC patients (median follow-up: 25 months), abiraterone plus prednisone was effective and safe.

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QoL, measured with various tools, remained stable during treatment with abiraterone plus prednisone.

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The median time to pain progression was 31.1 months.

The central role of Sphingosine kinase 1 in the development of neuroendocrine prostate cancer (NEPC): A new targeted therapy of NEPC

Background

Neuroendocrine prostate cancer (NEPC) is often diagnosed as a sub‐type from the castration‐resistant prostate cancer (CRPC) recurred from the second generation of anti‐androgen treatment and is a rapidly progressive fatal disease. The molecular mechanisms underlying the trans‐differentiation from CRPC to NEPC are not fully characterized, which hampers the development of effective targeted therapy.

Methods

Bioinformatic analyses were conducted to determine the clinical correlation of sphingosine kinase 1 (SphK1) in CRPC progression. To investigate the transcriptional regulation SphK1 and neuroendocrine (NE) transcription factor genes, both chromosome immunoprecipitation and luciferase reporter gene assays were performed. To demonstrate the role of SphK1 in NEPC development, neurosphere assay was carried out along with several biomarkers determined by quantitative PCR and western blot. Furthermore, in vivo NEPC xenograft models and patient‐derived xenograft (PDX) model were employed to determine the effect of SphK1 inhibitors and target validation.

Results

Significant prevalence of SphK1 in NEPC development is observed from clinical datasets. SphK1 is transcriptionally repressed by androgen receptor‐RE1‐silencing transcription factor (REST) complex. Furthermore, sphingosine 1‐phosphate produced by SphK1 can modulate REST protein turnover via MAPK signaling pathway. Also, decreased REST protein levels enhance the expression of NE markers in CRPC, enabling the transition to NEPC. Finally, specific SphK1 inhibitors can effectively inhibit the growth of NEPC tumors and block the REST protein degradation in PDX.

Conclusions

SphK1 plays a central role in NEPC development, which offers a new target for this lethal cancer using clinically approved SphK1 inhibitors.

PP2A promotes apoptosis and facilitates docetaxel sensitivity via the PP2A/p‑eIF4B/XIAP signaling pathway in prostate cancer

Serine/threonine protein phosphatase 2A (PP2A) is a protein that has a wide range of biological functions. As prostate cancer progresses from hormone-sensitive prostate cancer to castration-resistant prostate cancer (CRPC), the expression level of PP2A has been found to decrease. The present study aimed to determine the roles that PP2A may play in prostate cancer and its association with the downstream factor, X-linked inhibitor of apoptosis (XIAP). First, the mRNA and protein expression levels of PP2A in LNCaP, DU145 and PC-3 prostate cancer cell lines were measured. Next, the population of PP2A heterodimers was increased using a PP2A agonist, DT061, in the DU145 and PC-3 cell lines. PP2A expression was then knocked down in the LNCaP cell line. Western blot analysis was performed to determine the association between PP2A, phosphorylated (p)-eukaryotic initiation factor 4B (eIF4B) and XIAP. The results revealed that following the increase in PP2A expression, the DU145 and PC-3 cell lines were more sensitive to docetaxel according to Cell Counting Kit-8 assays and had an increased apoptotic rate as assessed by flow cytometry. Conversely, following the transfection of small interfering (si)PP2A into the LNCaP cell line, the sensitivity to docetaxel decreased, as well as the apoptotic rate. In addition, following treatment with the PP2A agonist, DT061, PP2A expression was found to be significantly upregulated, while p-eIF4B and XIAP protein expression levels were significantly downregulated. By contrast, following the transfection of siPP2A into the LNCaP cell line, PP2A protein expression levels were found to be downregulated, while p-eIF4B and XIAP expression levels were significantly upregulated. In conclusion, by affecting the downstream factor XIAP, PP2A may play a key role in promoting apoptosis and facilitating docetaxel sensitivity in prostate cancer cell lines.

A combined signature of glycolysis and immune landscape predicts prognosis and therapeutic response in prostate cancer

Prostate cancer (PCa) is a common malignancy that poses a major threat to the health of men. Prostate-specific antigen (PSA) and its derivatives, as FDA-approved detection assays, are insufficient to serve as optimal markers for patient prognosis and clinical decision-making. It is widely acknowledged that aberrant glycolytic metabolism in PCa is related to tumor progression and acidifies the tumor microenvironment (TME). Considering the non-negligible impacts of glycolysis and immune functions on PCa, we developed a combined classifier in prostate cancer. The Glycolysis Score containing 19 genes and TME Score including three immune cells were created, using the univariate and multivariate Cox proportional hazards model, log-rank test, least absolute shrinkage and selection operator (LASSO) regression analysis and the bootstrap approach. Combining the glycolysis and immunological landscape, the Glycolysis-TME Classifier was then constructed. It was observed that the classifier was more accurate in predicting the prognosis of patients than the current biomarkers. Notably, there were significant differences in metabolic activity, signaling pathways, mutational landscape, immunotherapeutic response, and drug sensitivity among the Glycolysis^high/TME^low, Mixed group and Glycolysis^low/TME^high identified by this classifier. Overall, due to the significant prognostic value and potential therapeutic guidance of the Glycolysis-TME Classifier, we anticipate that this classifier will be clinically beneficial in the management of patients with PCa.

FOXO3a and Its Regulators in Prostate Cancer

Forkhead box O3 (FOXO3a) is a member of a subfamily of forkhead transcription factors involved in the basic processes within a cell, including proliferation, apoptosis, cell cycle regulation, and DNA damage. As a transcription factor, FOXO3a is involved in the response to cellular stress, UV radiation, or oxidative stress. Its regulation is based on the modification of proteins as well as regulation by other proteins, e.g., growth factors. FOXO3a is commonly deregulated in cancer cells, and its inactivation is associated with initiation and progression of tumorigenesis, suggesting its role as a tumor suppressor; however, its role is still disputed and seems to be dependent on upstream signaling. Nevertheless, FOXO3a serves as an interesting potential target in therapies as it is regulated during treatment with very common anti-cancer drugs such as paclitaxel, cisplatin, docetaxel, and doxorubicin. This review aims to update the reported role of FOXO3a in prostate cancer (PCa), with a focus on its regulators that might serve as potential therapeutic agents in PCa therapy.

Impact of Serum γ-Glutamyltransferase on Overall Survival in Men with Metastatic Castration-Resistant Prostate Cancer Treated with Docetaxel

Simple Summary

γ-Glutamyltransferase (GGT) is a biomarker of oxidative stress and its elevation in the serum is linked to poor survival in various malignancies; however, reports on metastatic castration-resistant prostate cancer (mCRPC) are scarce. Moreover, the source of serum GGT in men with mCRPC is largely unknown. The aims of this study were to determine the impact of serum GGT on overall survival in men with mCRPC receiving docetaxel therapy, and to examine the association between systemic and local GGT levels using immunohistochemistry. Of note, high serum GGT was associated with adverse overall survival as were low hemoglobin and high prostate-specific antigen levels. Additionally, tissue GGT expression status in prostate specimens was moderately positively associated with serum GGT. We demonstrated that pre-therapeutic serum GGT was an independent prognosticator in men with mCRPC receiving docetaxel therapy, and that overexpression of GGT in cancer cells might be responsible for the elevation of serum GGT.

Abstract

Background: Reports on the prognostic significance of serum γ-glutamyltransferase (GGT) in men with metastatic castration-resistant prostate cancer (mCRPC) are limited. In addition, GGT expression status in cancer tissues has not been well characterized regardless of cancer types. Methods: This retrospective study included 107 consecutive men with mCRPC receiving docetaxel therapy. The primary endpoints were associations of serum GGT with overall survival (OS) and prostate-specific antigen (PSA) response. The secondary endpoint was an association of serum GGT with progression-free survival (PFS). Additionally, GGT expression status was immunohistochemically semi-quantified using tissue microarrays. Results: A total of 67 (63%) men died during follow-up periods (median 22.5 months for survivors). On multivariable analysis, high Log GGT was independently associated with adverse OS (HR 1.49, p = 0.006) as were low hemoglobin (HR 0.79, p = 0.002) and high PSA (HR 1.40, p < 0.001). In contrast, serum GGT was not significantly associated with PSA response or PFS. Moreover, incorporation of serum GGT into established prognostic models (i.e., Halabi and Smaletz models) increased their C-indices for predicting OS from 0.772 to 0.787 (p = 0.066) and from 0.777 to 0.785 (p = 0.118), respectively. Furthermore, there was a positive correlation between serum and tissue GGT levels (ρ = 0.53, p = 0.003). Conclusions: Serum GGT may be a prognostic biomarker in men with mCRPC receiving docetaxel therapy. GGT overexpression by prostate cancer cells appears to be responsible for the elevation of GGT in the serum.

Induction of Endoplasmic Reticulum Stress-Mediated Apoptosis by Aminosteroid RM-581 Efficiently Blocks the Growth of PC-3 Cancer Cells and Tumors Resistant or Not to Docetaxel

Aminosteroid derivative RM-581 was previously identified as an endoplasmic-reticulum (ER) stress inducer with potent in vitro and in vivo anticancer activities. We report its evaluation in androgen-independent prostate cancer (PC-3) cells. RM-581 efficiently blocks PC-3 cell proliferation with stronger activity than that of a selection of known antineoplastic agents. This later also showed a synergistic effect with docetaxel, able to block the proliferation of docetaxel-resistant PC-3 cells and, contrary to docetaxel, did not induce cell resistance. RM-581 induced an increase in the expression level of ER stress-related markers of apoptosis, potentially triggered by the presence of RM-581 in the ER of PC-3 cells. These in vitro results were then successfully translated in vivo in a PC-3 xenograft tumor model in nude mice, showing superior blockade than that of docetaxel. RM-581 was also able to stop the progression of PC-3 cells when they had become resistant to docetaxel treatment. Concomitantly, we observed a decrease in gene markers of mevalonate and fatty acid pathways, and intratumoral levels of cholesterol by 19% and fatty acids by 22%. Overall, this work demonstrates the potential of an ER stress inducer as an anticancer agent for the treatment of prostate cancers that are refractory to commonly used chemotherapy treatments.

Molecular Basis of Prostate Cancer and Natural Products as Potential Chemotherapeutic and Chemopreventive Agents

Prostate cancer is the second most common malignant cancer in males. It involves a complex process driven by diverse molecular pathways that closely related to the survival, apoptosis, metabolic and metastatic characteristics of aggressive cancer. Prostate cancer can be categorized into androgen dependent prostate cancer and castration-resistant prostate cancer and cure remains elusive due to the developed resistance of the disease. Natural compounds represent an extraordinary resource of structural scaffolds with high diversity that can offer promising chemical agents for making prostate cancer less devastating and curable. Herein, those natural compounds of different origins and structures with potential cytotoxicity and/or in vivo anti-tumor activities against prostate cancer are critically reviewed and summarized according to the cellular signaling pathways they interfere. Moreover, the anti-prostate cancer efficacy of many nutrients, medicinal plant extracts and Chinese medical formulations were presented, and the future prospects for the application of these compounds and extracts were discussed. Although the failure of conventional chemotherapy as well as involved serious side effects makes natural products ideal candidates for the treatment of prostate cancer, more investigations of preclinical and even clinical studies are necessary to make use of these medical substances reasonably. Therefore, the elucidation of structure-activity relationship and precise mechanism of action, identification of novel potential molecular targets, and optimization of drug combination are essential in natural medicine research and development.

Real world treatment utilization patterns in patients with castration-resistant prostate cancer

BACKGROUND

Studies describing treatment utilization for castration-resistant prostate cancer (CRPC) are limited. We aimed to describe the treatment utilization of a contemporary population-based CRPC cohort between 2006 and 2016.

METHODS

We identified 1699 men with a PC diagnosis between 2005 and 2015, who developed CRPC between 2006 and 2015 in the Stockholm region of Sweden. Demographic information, stage and grade at PC diagnosis, stage at CRPC, prostate-specific antigen (PSA) nadir, PSA doubling time, treatment utilization rate within 1 year of CRPC diagnosis, reason for stopping therapy, treatment sequence trajectory, overall and PC specific survival was described.

RESULTS

Treatment for men with de novo metastatic disease (n = 463) was 32%, treatment for men with progressive metastatic disease after PC diagnosis (n = 66) was 44%, treatment for men with nonmetastatic CRPC (n = 113) was 34% and treatment for those with an unknown stage at time of CRPC diagnosis (n = 857) was 12%. Docetaxel was used in 39%, abiraterone acetate plus prednisone in 15%, enzalutamide in 13%, cabazitaxel in 11% and radium-223 in 5% of treatments. Treatment increased from 22% in 2006-2009 for metastatic cancer to 50% in 2013-2015 (p < .001). Factors associated with treatment were an unknown stage at diagnosis (OR: 0.3, 95% CI: 0.2-0.4), age ≥75 years (OR: 0.2, 95% CI: 0.1 - 0.3), PSA doubling time >3 months (OR: 0.4, 95% CI: 0.3 - 0.6) and a diagnosis between 2013 and 2015 (OR: 3.4, 95% CI: 2.0 - 5.8).

CONCLUSIONS

Despite treatment availability, in this large real-world cohort we found treatment utilization to remain low.

Suppressing BCL-XL increased the high dose androgens therapeutic effect to better induce the Enzalutamide-resistant prostate cancer autophagic cell death

Most patients with advanced prostate cancer (PCa) initially respond well to androgen deprivation therapy (ADT) with antiandrogens, but most of them eventually become resistant to ADT. Here, we found that the antiandrogen Enzalutamide-resistant (EnzR) PCa cells can be suppressed by hyper-physiological doses of the androgen DHT. Mechanism dissection indicates that while androgens/androgen receptor (AR) can decrease BCL-2 expression to induce cell death, yet they can also simultaneously increase anti-apoptosis BCL-XL protein expression via decreasing its potential E3 ubiquitin ligase, PARK2, through transcriptionally increasing the miR-493-3p expression to target PARK2. Thus, targeting the high dose DHT/AR/miR-493-3p/PARK2/BCL-XL signaling with BCL-XL-shRNA can increase high-dose-DHT effect to better suppress EnzR cell growth via increasing the autophagic cell death. A preclinical study using in vivo mouse model also validated that suppressing BCL-XL led to enhance high dose DHT effect to induce PCa cell death. The success of human clinical trials in the future may help us to develop a novel therapy using high dose androgens to better suppress CRPC progression.

Neutropenia Prevention in the Treatment of Post-docetaxel Metastatic, Castration-resistant Prostate Cancer With Cabazitaxel and Prednisone: A Multicenter, Open-label, Single-arm Phase IV Study

INTRODUCTION

Severe neutropenia is a dose-limiting factor that occurs in up to 82% of patients with metastatic castration-resistant prostate cancer (mCRPC) treated with cabazitaxel. This study evaluated the effectiveness of granulocyte colony-stimulating factor (G-CSF) plus ciprofloxacin as prophylaxis in post-docetaxel patients with mCRPC treated with cabazitaxel and at high risk for neutropenia.

PATIENTS AND METHODS

This was a phase IV, multicenter, open-label, single-arm interventional study with men aged ≥ 65 years (or < 65 years and ≥ 25% irradiated bone marrow), presenting with mCRPC after docetaxel failure, performance status ≤ 1, and life expectancy > 12 weeks. Cabazitaxel 25 mg/m² and prednisone were given on day 1, every 21 days. G-CSF was administered on days 2 to 8 of each cycle or until an absolute neutrophil count > 2000/mm³, and ciprofloxacin 1000 mg was given orally on days 5 to 12. The rate of neutropenia grade ≥ 3 during the first cycle (primary endpoint), and frequency of neutropenia grade ≥ 3, febrile neutropenia, diarrhea grade ≥ 3, prostate-specific antigen response, and quality of life during treatment (secondary end points) were estimated.

RESULTS

We included 46 patients. The mean number of cabazitaxel cycles was 9.5. During the first cycle, 40.0% of patients had neutropenia grade ≥ 3, and 42.2% had at least 1 episode of neutropenia during treatment. Febrile neutropenia and diarrhea grade ≥ 3 occurred in 1 patient each. Twenty-nine (64.4%) patients achieved prostate-specific antigen response, and 77.2% improved quality of life scores in at least 1 visit.

CONCLUSIONS

Prophylactic G-CSF was effective in preventing neutropenia grade ≥ 3 and other hematologic complications during treatment with cabazitaxel 25 mg/m² in post-docetaxel patients with mCRPC at high risk for neutropenia. The role of prophyclatic ciprofloxacin to prevent febrile neutropenia in this setting is still unclear and needs to be further evaluated.

Assessment of a Clinical Trial-Derived Survival Model in Patients With Metastatic Castration-Resistant Prostate Cancer

IMPORTANCE

Randomized clinical trials (RCTs) are considered the criterion standard for clinical evidence. Despite their many benefits, RCTs have limitations, such as costliness, that may reduce the generalizability of their findings among diverse populations and routine care settings.

OBJECTIVE

To assess the performance of an RCT-derived prognostic model that predicts survival among patients with metastatic castration-resistant prostate cancer (CRPC) when the model is applied to real-world data from electronic health records (EHRs).

DESIGN, SETTING, AND PARTICIPANTS

The RCT-trained model and patient data from the RCTs were obtained from the Dialogue for Reverse Engineering Assessments and Methods (DREAM) challenge for prostate cancer, which occurred from March 16 to July 27, 2015. This challenge included 4 phase 3 clinical trials of patients with metastatic CRPC. Real-world data were obtained from the EHRs of a tertiary care academic medical center that includes a comprehensive cancer center. In this study, the DREAM challenge RCT-trained model was applied to real-world data from January 1, 2008, to December 31, 2019; the model was then retrained using EHR data with optimized feature selection. Patients with metastatic CRPC were divided into RCT and EHR cohorts based on data source. Data were analyzed from March 23, 2018, to October 22, 2020.

EXPOSURES

Patients who received treatment for metastatic CRPC.

MAIN OUTCOMES AND MEASURES

The primary outcome was the performance of an RCT-derived prognostic model that predicts survival among patients with metastatic CRPC when the model is applied to real-world data. Model performance was compared using 10-fold cross-validation according to time-dependent integrated area under the curve (iAUC) statistics.

RESULTS

Among 2113 participants with metastatic CRPC, 1600 participants were included in the RCT cohort, and 513 participants were included in the EHR cohort. The RCT cohort comprised a larger proportion of White participants (1390 patients [86.9%] vs 337 patients [65.7%]) and a smaller proportion of Hispanic participants (14 patients [0.9%] vs 42 patients [8.2%]), Asian participants (41 patients [2.6%] vs 88 patients [17.2%]), and participants older than 75 years (388 patients [24.3%] vs 191 patients [37.2%]) compared with the EHR cohort. Participants in the RCT cohort also had fewer comorbidities (mean [SD], 1.6 [1.8] comorbidities vs 2.5 [2.6] comorbidities, respectively) compared with those in the EHR cohort. Of the 101 variables used in the RCT-derived model, 10 were not available in the EHR data set, 3 of which were among the top 10 features in the DREAM challenge RCT model. The best-performing EHR-trained model included only 25 of the 101 variables included in the RCT-trained model. The performance of the RCT-trained and EHR-trained models was adequate in the EHR cohort (mean [SD] iAUC, 0.722 [0.118] and 0.762 [0.106], respectively); model optimization was associated with improved performance of the best-performing EHR model (mean [SD] iAUC, 0.792 [0.097]). The EHR-trained model classified 256 patients as having a high risk of mortality and 256 patients as having a low risk of mortality (hazard ratio, 2.7; 95% CI, 2.0-3.7; log-rank P < .001).

CONCLUSIONS AND RELEVANCE

In this study, although the RCT-trained models did not perform well when applied to real-world EHR data, retraining the models using real-world EHR data and optimizing variable selection was beneficial for model performance. As clinical evidence evolves to include more real-world data, both industry and academia will likely search for ways to balance model optimization with generalizability. This study provides a pragmatic approach to applying RCT-trained models to real-world data.

CMTM5-v1 inhibits cell proliferation and migration by downregulating oncogenic EGFR signaling in prostate cancer cells

Anomalous epidermal growth factor receptor (EGFR) signaling plays an important role in the progression of prostate cancer (PCa) and the transformation to castration-resistant PCa (CRPC). A novel tumor suppressor CKLF-like MARVEL transmembrane domain-containing member 5(CMTM5) has a MARVEL domain and may regulate transmembrane signaling. Thus, we postulated that CMTM5 could regulate EGFR and its downstream molecules to affect the biological behaviors of PCa cells. In this study, we found that CMTM5 was expressed in benign prostatic hyperplasia (BPH) tissues but was undetectable in PCa cells. However, the EGFR was upregulated in PCa cells, especially in two metastatic CRPC cell lines, PC3 and DU145. Furthermore, ectopic expression of CMTM5-v1 suppressed cell proliferation and migration and p-EGFR levels. Further investigation revealed that restoration of CMTM5-v1 inhibited not only EGF-mediated proliferation but also chemotactic migration by EGF in PC3 and DU145 cells. Moreover, mechanistic studies showed that CMTM5-v1 attenuated EGF-induced receptor signaling by repressing EGFR and Akt phosphorylation in PCa cells, which were essential for malignant features. Finally, CMTM5-v1can promote the sensitivity of PC3 cells to Gefetinib, a tyrosine kinase inhibitor (TKI) targeting the EGFR. These observations indicate that CMTM5-v1 suppressed PCa cells through EGFR signaling. The loss of CMTM5 may participate in the progression of PCa resulting from deregulated EGFR, and CMTM5 might be associated with the efficacy of TKIs in terms of their potent inhibition of EGFR and human epidermal growth factor-2 (HER2) activation.

PSMA ADC monotherapy in patients with progressive metastatic castration-resistant prostate cancer following abiraterone and/or enzalutamide: Efficacy and safety in open-label single-arm phase 2 study

BACKGROUND

Prostate-specific membrane antigen (PSMA) is a well-established therapeutic and diagnostic target overexpressed in both primary and metastatic prostate cancers. PSMA antibody-drug conjugate (PSMA ADC) is a fully human immunoglobulin G1 anti-PSMA monoclonal antibody conjugated to monomethylauristatin E, which binds to PSMA-positive cells and induces cytotoxicity. In a phase 1 study, PSMA ADC was well tolerated and demonstrated activity as measured by reductions in serum prostate-specific antigen (PSA) and circulating tumor cells (CTCs). To further assess PSMA ADC, we conducted a phase 2 trial in metastatic castration-resistant prostate cancer (mCRPC) subjects who progressed following abiraterone/enzalutamide (abi/enz) therapy.

METHODS

A total of 119 (84 chemotherapy-experienced and 35 chemotherapy-naïve) subjects were administered PSMA ADC 2.5 or 2.3 mg/kg IV q3w for up to eight cycles. Antitumor activity (best percentage declines in PSA and CTCs from baseline and tumor responses through radiological imaging), exploratory biomarkers, and safety (monitoring of adverse events [AEs], clinical laboratory tests, and Eastern Cooperative Oncology Group performance status) were assessed.

RESULTS

PSA declines ≥50% occurred in 14% of all treated (n = 113) and 21% of chemotherapy-naïve subjects (n = 34). CTC declines ≥50% were seen in 78% of all treated (n = 77; number of subjects with ≥5 CTCs at baseline and a posttreatment result) and 89% of chemotherapy-naïve subjects (n = 19); 47% of all treated and 53% of chemotherapy-naïve subjects had a transition from ≥5 to less than 5 CTCs/7.5 mL blood at some point during the study. PSA and CTC reductions were associated with high PSMA expression (CTCs or tumor tissue) and low neuroendocrine serum markers. In the chemotherapy-experienced group, the best overall radiologic response to PSMA ADC treatment was stable disease in 51 (60.7%) subjects; 5.7% of subjects in the chemotherapy-naïve group had partial responses. The most common treatment-related AEs ≥Common Terminology Criteria for AE (CTCAE) grade 3 were neutropenia, fatigue, electrolyte imbalance, anemia, and neuropathy. The most common serious AEs were dehydration, hyponatremia, febrile neutropenia, and constipation. Two subjects who received 2.5 mg/kg died of sepsis.

CONCLUSIONS

PSMA ADC demonstrated some activity with respect to PSA declines, CTC conversions/reductions, and radiologic assessments in abi/enz treated mCRPC subjects. Clinically significant treatment-related AEs included neutropenia and neuropathy.

Gene Expression Alterations during Development of Castration-Resistant Prostate Cancer Are Detected in Circulating Tumor Cells

Development of castration-resistant prostate cancer (CRPC) is associated with alterations in gene expression involved in steroidogenesis and androgen signaling. This study investigates whether gene expression changes related to CRPC development can be identified in circulating tumor cells (CTCs). Gene expression in paired CTC samples from 29 patients, before androgen deprivation therapy (ADT) and at CRPC relapse, was compared using a panel including 47 genes related to prostate cancer progression on a qPCR platform. Fourteen genes displayed significantly changed gene expression in CTCs at CRPC relapse compared to before start of ADT. The genes with increased expression at CRPC relapse were related to steroidogenesis, AR-signaling, and anti-apoptosis. In contrast, expression of prostate markers was downregulated at CRPC. We also show that midkine (MDK) expression in CTCs from metastatic hormone-sensitive prostate cancer (mHSPC) was associated to short cancer-specific survival (CSS). In conclusion, this study shows that gene expression patterns in CTCs reflect the development of CRPC, and that MDK expression levels in CTCs are prognostic for cancer-specific survival in mHSPC. This study emphasizes the role of CTCs in exploring mechanisms of therapy resistance, as well as a promising biomarker for prognostic and treatment-predictive purposes in advanced mHSPC.

Identification of key regulators in prostate cancer from gene expression datasets of patients

Identification of key regulators and regulatory pathways is an important step in the discovery of genes involved in cancer. Here, we propose a method to identify key regulators in prostate cancer (PCa) from a network constructed from gene expression datasets of PCa patients. Overexpressed genes were identified using BioXpress, having a mutational status according to COSMIC, followed by the construction of PCa Interactome network using the curated genes. The topological parameters of the network exhibited power law nature indicating hierarchical scale-free properties and five levels of organization. Highest degree hubs (k ≥ 65) were selected from the PCa network, traced, and 19 of them was identified as novel key regulators, as they participated at all network levels serving as backbone. Of the 19 hubs, some have been reported in literature to be associated with PCa and other cancers. Based on participation coefficient values most of these are connector or kinless hubs suggesting significant roles in modular linkage. The observation of non-monotonicity in the rich club formation suggested the importance of intermediate hubs in network integration, and they may play crucial roles in network stabilization. The network was self-organized as evident from fractal nature in topological parameters of it and lacked a central control mechanism.

PREVALENCE OF FATIGUE AND IMPACT ON QUALITY OF LIFE IN CASTRATION-RESISTANT PROSTATE CANCER PATIENTS: the VITAL study

Background

Fatigue is one of the most prevalent symptoms among cancer patients. Specifically, in metastatic castration-resistant prostate cancer (mCRPC) patients, fatigue is the most common adverse event associated with current treatments. The purpose of this study is to describe the prevalence of fatigue and its impact on quality of life (QoL) in patients with CRPC in routine clinical practice.

Methods

This was a cross-sectional, multicentre study. Male chemo-naïve adults with high-risk non-metastatic (M0) CRPC and metastatic (M1) CRPC (mCRPC) were eligible. Fatigue was measured using the Brief Fatigue Inventory (BFI) and QoL was assessed using the Functional Assessment of Cancer Therapy questionnaire for patients with prostate cancer (FACT-P) and the FACT-General (FACT-G) questionnaire. Data were analysed using Mann-Whitney or Kruskal-Wallis tests (non-parametric distribution), a T-test or an ANOVA (parametric distribution) and the Fisher or chi-squared tests (categorical variables).

Results

A total of 235 eligible patients were included in the study (74 [31.5%] with M0; and 161 [68.5%] with M1). Fatigue was present in 74%, with 38.5% of patients reporting moderate-to-severe fatigue. Mean FACT-G and FACT-P overall scores were 77.6 ± 16.3 and 108.7 ± 21.4, respectively, with no differences between the CRPC M0 and CRPC M1 subgroups. Fatigue intensity was associated with decreased FACT-G/P scores, with no differences between groups. Among 151 mCRPC patients with available treatment data, those treated with abiraterone-prednisone ≥3 months showed a significant reduction in fatigue intensity (p = 0.043) and interference (p = 0.04) compared to those on traditional hormone therapy (HT). Patients on abiraterone-prednisone ≥3 months showed significantly better FACT-G/P scores than patients on HT (p = 0.046 and 0.018, respectively).

Conclusion

Our data show a high prevalence and intensity of fatigue and its impact on QoL in chemo-naïve CRPC patients. There is an association between greater fatigue and less QoL, irrespective of the presence or absence of metastasis. Chemo-naïve mCRPC patients receiving more than 3 months of abiraterone acetate plus prednisone showed an improvement of fatigue and QoL when compared to those on traditional HT.

Trial registration

Not applicable since it is not an interventional study.

A Novel Small Molecule Inhibits Tumor Growth and Synergizes Effects of Enzalutamide on Prostate Cancer

Prostate cancer (PCa) is the second leading cause of cancer-related death for men in the United States. Approximately 35% of PCa recurs and is often transformed to castration-resistant prostate cancer (CRPCa), the most deadly and aggressive form of PCa. However, the CRPCa standard-of-care treatment (enzalutamide with abiraterone) usually has limited efficacy. Herein, we report a novel molecule (PAWI-2) that inhibits cellular proliferation of androgen-sensitive and androgen-insensitive cells (LNCaP and PC-3, respectively). In vivo studies in a PC-3 xenograft model showed that PAWI-2 (20 mg/kg per day i.p., 21 days) inhibited tumor growth by 49% compared with vehicle-treated mice. PAWI-2 synergized currently clinically used enzalutamide in in vitro inhibition of PCa cell viability and resensitized inhibition of in vivo PC-3 tumor growth. Compared with vehicle-treated mice, PC-3 xenograft studies also showed that PAWI-2 (20 mg/kg per day i.p., 21 days) and enzalutamide (5 mg/kg per day i.p., 21 days) inhibited tumor growth by 63%. Synergism was mainly controlled by the imbalance of prosurvival factors (e.g., Bcl-2, Bcl-xL, Mcl-1) and antisurvival factors (e.g., Bax, Bak) induced by affecting mitochondrial membrane potential/mitochondria dynamics. Thus, PAWI-2 utilizes a distinct mechanism of action to inhibit PCa growth independently of androgen receptor signaling and overcomes enzalutamide-resistant CRPCa. SIGNIFICANCE STATEMENT: Castration-resistant prostate cancer (CRPCa) is the most aggressive human prostate cancer (PCa) but standard chemotherapies for CRPCa are largely ineffective. PAWI-2 potently inhibits PCa proliferation in vitro and in vivo regardless of androgen receptor status and uses a distinct mechanism of action. PAWI-2 has greater utility in treating CRPCa than standard-of-care therapy. PAWI-2 possesses promising therapeutic potency in low-dose combination therapy with a clinically used drug (e.g., enzalutamide). This study describes a new approach to address the overarching challenge in clinical treatment of CRPCa.

The role of ketoconazole in current prostate cancer care

Ketoconazole is a nonselective steroid 17α-hydroxylase/17,20 lyase (CYP17A1) inhibitor that has been used, off-label, as a second-line therapy for castration-resistant prostate cancer (CRPC). The drug has shown clinical efficacy without survival benefit. Despite not improving survival, ketoconazole has beneficial characteristics, such as its low cost, a relatively favourable toxicity profile compared with chemotherapy, and its efficacy both before and after chemotherapy. The approval of several new, highly effective treatments, including abiraterone acetate, enzalutamide, and apalutamide, warrants re-evaluation of the role of ketoconazole and other classic agents in achieving the optimal timing and sequencing of available agents to prolong survival and maintain patients' quality of life. In the current CRPC treatment landscape, we believe that ketoconazole can be considered in patients with nonmetastatic CRPC and in those with metastatic CRPC who do not respond to, tolerate, or have access to chemotherapy and other standard therapeutic options.

Identification of biomarker microRNA-mRNA regulatory pairs for predicting the docetaxel resistance in prostate cancer

Background: Docetaxel resistance is a cursing problem with adverse effects on the therapeutic efficacy of prostate cancer (PCa), involving interactions among multiple molecular components. Single or limited molecules are not strong enough as prediction biomarkers of drug resistance. Network biomarkers are considered to outperform individual markers in disease characterization.

Methods: In this study, key microRNAs (miRNAs) as biomarkers were identified from the PubMed citations and miRNA expression profiles. Targets of miRNAs were predicted and enriched by biological function analysis. Key target mRNAs of the biomarker miRNAs were screened from protein-protein interaction network and gene expression profiles, respectively. The results were validated by the assessment of their predictive power and system biological analysis.

Results: With this approach, we identified 13 miRNAs and 31 target mRNAs with 66 interactions in the constructed network. Integrative functional enrichment analysis and literature exploration further confirmed that the network biomarkers were highly associated with the development of docetaxel resistance.

Conclusions: The findings from our results demonstrated that the identified network biomarkers provide a useful tool for predicting the docetaxel resistance and may be helpful for serving as prediction biomarkers and therapeutic targets. However, it is necessary to conduct biological experiments for further investigating their roles in the development of docetaxel resistance.

Efficacy and safety of abiraterone acetate plus prednisone vs. cabazitaxel as a subsequent treatment after first-line docetaxel in metastatic castration-resistant prostate cancer: results from a prospective observational study (CAPRO)

BACKGROUND

To describe the patterns of second-line treatment of patients with metastatic castration-resistant prostate cancer (mCRPC) after docetaxel treatment in a Spanish population, to identify the factors associated with those patterns, and to compare the efficacy and safety of the treatments most frequently administered.

METHODS

Observational, prospective study conducted in patients with histologically or cytologically confirmed prostate adenocarcinoma; documented metastatic castration-resistant disease; progression after first-line, docetaxel-based chemotherapy with or without other agents.

RESULTS

Of the 150 patients recruited into the study, 100 patients were prescribed abiraterone acetate plus prednisone (AAP), 44 patients received cabazitaxel plus prednisone (CP), and 6 patients received other treatments. Age (odds ratio [OR] 1.06, 95% [confidence interval] CI 1.01 to 1.11) and not elevated lactate dehydrogenase (LDH) levels (OR 0.33, 95% CI 0.14 to 0.76) were independently associated with the administration of AAP. Treatment with AAP was associated with significantly longer clinical/radiographic progression-free survival (hazard ratio [HR] 0.57, 95% CI 0.38 to 0.85) and overall survival (OS; HR 0.40, 95% CI 0.21 to 0.76) compared to CP, while no significant differences between the treatments were found regarding biochemical progression-free survival (PFS; HR 0.78 [95% CI 0.49 to 1.24]). However, in a post-hoc Cox regression analysis adjusted for potential confounders there were not differences between AAP and CP in any of the time-to-event outcomes, including overall survival. We observed no new safety signals related to either regimen.

CONCLUSION

Second-line AAP for patients with mCRPC is the most common treatment strategy after progression with a docetaxel-based regimen. When controlling for potential confounders, patients receiving this treatment showed no differences in PFS and OS in comparison to those receiving CP, although these latter results should be confirmed in randomized controlled trials.

Genomic analysis of Korean patients with advanced prostate cancer by use of a comprehensive next-generation sequencing panel and low-coverage, whole-genome sequencing

Purpose

To analyze the characteristics of somatic mutations and copy number alterations (CNAs) in Korean patients with advanced prostate cancer (PCa) by use of the Oncomine Comprehensive Panel (ThermoFisher Scientific) and low-coverage, whole-genome sequencing (LC-WGS).

Materials and Methods

We retrospectively analyzed PCa tissues obtained from 14 patients with advanced PCa (metastatic tumor, 12 [85.7%]; nonmetastatic castration-resistant PCa, 1 [7.1%]; pT3b, 1 [7.1%]) from 2009 to 2017. The Oncomine Comprehensive Panel included a total of 143 genes. Moreover, LC-WGS was performed to detect CNAs of the entire genome. Two plasma samples matched with tumor tissues were analyzed using LC-WGS to compare the chromosomal aberration patterns between circulating tumor DNA and tumor tissue.

Results

Genetic alterations were most frequently observed in the androgen receptor (AR) (42.9%, n=6/14), TP53 (14.3%, n=2/14), and PTEN (14.3%, n=2/14) genes in the Oncomine panel. AR amplification was the most common CNA (35.7%, n=5/14). As a result of LC-WGS, CNAs were confirmed in about 92.9% (n=13/14) of the samples in regions Xq12, 8q24.21, and 11q13.3 (gains) and in regions 6q16.1, 8p23.1, 10q25.1, 16q24.2, 18q12.3, Xq25, and Xq26.3 (losses). All CNAs identified in the Oncomine panel matched the results of LC-WGS. Additionally, LC-WGS of two plasma samples that matched tumor tissues revealed that CNA patterns of plasma samples (circulating tumor DNA) were very similar to those detected in tumor samples.

Conclusions

Our data showed that the characteristics of mutations and CNAs in Korean patients with advanced PCa were similar to those observed in previous studies.

Phase 1 study of PSMA ADC, an antibody-drug conjugate targeting prostate-specific membrane antigen, in chemotherapy-refractory prostate cancer

BACKGROUND

Prostate-specific membrane antigen (PSMA) is a well-characterized target that is overexpressed selectively on prostate cancer cells. PSMA antibody-drug conjugate (ADC) is a fully human IgG1 monoclonal antibody conjugated to the microtubule disrupting agent monomethyl auristatin E (MMAE), which is designed to specifically bind PSMA-positive cells, internalize, and then release its cytotoxic payload into the cells. PSMA ADC has demonstrated potent and selective antitumor activity in preclinical models of advanced prostate cancer. A Phase 1 study was conducted to assess the safety, pharmacokinetics, and preliminary antitumor effects of PSMA ADC in subjects with treatment-refractory prostate cancer.

METHODS

In this first-in-man dose-escalation study, PSMA ADC was administered by intravenous infusion every three weeks to subjects with progressive metastatic castration-resistant prostate cancer (mCRPC) who were previously treated with docetaxel chemotherapy. The primary endpoint was to establish a maximum tolerated dose (MTD). The study also examined the pharmacokinetics of the study drug, total antibody, and free MMAE. Antitumor effects were assessed by measuring changes in serum prostate-specific antigen (PSA), circulating tumor cells (CTCs), and radiologic imaging.

RESULTS

Fifty-two subjects were administered doses ranging from 0.4 to 2.8 mg/kg. Subjects had a median of two prior chemotherapy regimens and prior treatment with abiraterone and/or enzalutamide. Neutropenia and peripheral neuropathy were identified as important first-cycle and late dose-limiting toxicities, respectively. The dose of 2.5 mg/kg was determined to be the MTD. Pharmacokinetics were approximately dose-proportional with minimal drug accumulation. Reductions in PSA and CTCs in subjects treated with doses of ≥1.8 mg/kg were durable and often concurrent.

CONCLUSIONS

In an extensively pretreated mCRPC population, PSMA ADC demonstrated acceptable toxicity. Antitumor activity was observed over dose ranges up to and including 2.5 mg/kg. The observed anti-tumor activity supported further evaluation of this novel agent for the treatment of advanced metastatic prostate cancer.

HTA and innovative treatments evaluation: the case of metastatic castration-resistant prostate cancer

Purpose: To investigate the implications of the introduction of two hormonal therapies, abiraterone acetate + prednisone (AA+P) and enzalutamide (ENZA), for the treatment of naïve patients with metastatic castration-resistant prostate cancer (mCRPC) in the Italian setting.

Methods: In 2017–2018, a Health Technology Assessment was conducted in Italy, considering the National Healthcare Service (NHS) perspective. Data were retrieved from literature evidence, economic evaluations, and qualitative questionnaires, considering the 9 EUnetHTA dimensions, and a final multi-criteria approach.

Results: On the basis of mCRPC prevalence and incidence rates in Italy, the analysis considered 11,212 males eligible to either AA+P or ENZA treatments. Both drugs led to an improvement of the patients' overall survival, with respect to the standard of care, composed of docetaxel chemotherapy. However, AA+P showed a higher rate of drug-related moderate adverse events and a monitoring activities incidence superior to ENZA (+70%, p-value=0.00), which led to a major resources absorption (€ 1,056.02 vs € 316.25, p-value=0.00), whereas ENZA showed a better cost-effectiveness average value (CEV: 54,586.12 vs 57,624.15). Economic savings ranging from 1.46% to 1.61% emerged for the NHS, as well as organizational advantages, with fewer minutes required for the mCRPC management (AA+P: 815 mins vs ENZA: 500 mins). According to experts’ perceptions, based on a 7-item Likert scale (ranging from −3 to +3), similar results emerged on ethical and social impact (ENZA: 1.35 vs AA+P: 1.48, p-value>0.05), and on legal dimension (ENZA: 0.67 vs AA+P: 0.67, p-value>0.05), since both drugs improved the patients’ quality of life and received approval for use. High-level perceptions related to ENZA adoption emerged with regard to equity (ENZA: 0.69 vs AA+P: 0.25, p-value<0.05), since it is cortisone-free. Multi-criteria approach analysis highlighted a higher score of ENZA than comparator (0.79 vs 0.60, p-value=0.00).

Conclusion: The evidence-based information underlined the advantages of ENZA and AA+P treatments as therapeutic options for mCRPC patients. In the appraisal phase, the higher score than the comparator suggested ENZA as the preferred treatment for mCRPC.

Cell division cycle 20 (CDC20) drives prostate cancer progression via stabilization of β-catenin in cancer stem-like cells

Background

Cell division cycle 20 (CDC20) is frequently overexpressed in malignant tumours and involved in the differentiation process of hematopoietic stem cells. However, the role of CDC20 in prostate cancer stem-like cells (CSCs) remains poorly understood.

Methods

The expression of CDC20, CD44, β-catenin were examined in prostate cancer specimens by immunohistochemistry assay, the role of CDC20 on the stem-like properties of prostate CSCs was accessed by real-time quantitive PCR, spheroid formation, in vitro and in vivo limiting dilution assay.

Finding

CDC20 was associated with malignant progression of prostate cancer, the patients with both high expression CDC20 and CD44 or β-catenin were associated with more aggressive clinicopathological features and poor prognosis. CDC20 was usually enriched in CD44⁺ prostate CSCs. Knockdown of CDC20 could inhibit the expression of stemness-related genes, self-renewal ability, chemo-resistance, invasion capability and tumorigenicity of CD44⁺ prostate CSCs. Mechanistically, CDC20 promoted degradation of Axin1, the core member of β-catenin destruction complex, sequentially reduced the phosphorylation of β-catenin, promoting the latter into the nucleus, thereby enhancing the self-renewal capacity of CD44⁺ prostate CSCs.

Interpretation

Our results indicated that CDC20 maintains the self-renewal ability of CD44⁺ prostate CSCs by promoting nuclear translocation and trans-activation of β-catenin. In addition, CDC20 combined with CD44 or β-catenin can serve as an important indicator for prognosis of patients with prostate cancer.

Mitochondrial localization, import, and mitochondrial function of the androgen receptor

Nuclear localization of androgen receptor (AR) directs transcriptional regulation of a host of genes, referred to as genomic signaling. Additionally, nonnuclear or nongenomic activities of the AR have long been described, but understanding of these activities remains elusive. Here, we report that AR is imported into and localizes to mitochondria and has a novel role in regulating multiple mitochondrial processes. Employing complementary experimental approaches of AR knockdown in AR-expressing cells and ectopic AR expression in AR-deficient cells, we demonstrate an inverse relationship between AR expression and mitochondrial DNA (mtDNA) content and transcription factor A, mitochondrial (TFAM), a regulator of mtDNA content. We show that AR localizes to mitochondria in prostate tissues and cell lines and is imported into mitochondria in vitro We also found that AR contains a 36-amino-acid-long mitochondrial localization sequence (MLS) capable of targeting a passenger protein (GFP) to the mitochondria and that deletion of the MLS abolishes the import of AR into the mitochondria. Ectopic AR expression reduced the expression of oxidative phosphorylation (OXPHOS) subunits. Interestingly, AR also controlled translation of mtDNA-encoded genes by regulating expression of multiple nuclear DNA-encoded mitochondrial ribosomal proteins. Consistent with these observations, OXPHOS supercomplexes were destabilized, and OXPHOS enzymatic activities were reduced in AR-expressing cells and restored upon AR knockdown. Moreover, mitochondrial impairment induced AR expression and increased its translocation into mitochondria. We conclude that AR localizes to mitochondria, where it controls multiple mitochondrial functions and mitonuclear communication. Our studies also suggest that mitochondria are novel players in nongenomic activities of AR.

DNA Damage Response in Prostate Cancer

Prostatic adenocarcinoma (PCa) remains a significant health concern. Although localized PCa can be effectively treated, disseminated disease remains uniformly fatal. PCa is reliant on androgen receptor (AR); as such, first-line therapy for metastatic PCa entails suppression of AR signaling. Although initially effective, recurrent tumors reactivate AR function, leading to a lethal stage of disease termed castration-resistant PCa (CRPC). Recent findings implicate AR signaling in control of DNA repair and show that alterations in DNA damage repair pathways are strongly associated with disease progression and poor outcome. This review will address the DNA repair alterations observed in the clinical setting, explore the anticipated molecular and cellular consequence of DNA repair dysfunction, and consider clinical strategies for targeting tumors with altered DNA repair.

Prostate cancer in Asia: design of a patient registry to inform real-world treatments, outcomes, and quality of life

Background

The incidence of prostate cancer (PC) in Asian countries is increasing for reasons that are not clear. Data describing how PC is diagnosed and treated are fragmented across Asia, with marked intercountry and intracountry differences in outcome and knowledge gaps in clinical diagnostic and treatment practices. To address these knowledge gaps, we have established a PC disease registry with the aim of providing a comprehensive picture of PC diagnosis, prognosis, treatment and outcome, population characteristics, and comorbidities in real-world clinical practice in Asia.

Methods

This is a multinational, multicenter, longitudinal, and observational registry of PC patients presenting to participating tertiary-care hospitals in eight Asian countries (www.clinicaltrials.gov NCT02546908. Registry Identifier: NOPRODPCR4001). Approximately 3500-4000 eligible patients with existing or newly diagnosed high-risk localized PC (cohort 1), nonmetastatic biochemically recurrent PC (cohort 2), or metastatic PC (cohort 3) will be consecutively enrolled and followed-up for 5 years. An enrollment cap of 600 patients each will be applied to cohorts 1 and 2. Disease status is collected at enrollment, and outcome variables captured at 3-monthly intervals include diagnostic/staging, treatments including reason for change, laboratory results, comorbidities, and concomitant medications. Treatments and survival outcomes will be captured real time until study end. Patient-reported quality-of-life will be measured every 6 months, and medical resource utilization summarized at study end. Data analysis will include exploratory analyses of potential associations between multiple risk factors and socioeconomic variables with disease progression and evaluation of various treatments for PC including novel therapies on clinical outcome and health-related quality-of-life outcomes.

Results

3636 men with PC were enrolled until July 2018; 416 in cohort 1, 399 in cohort 2 and 2821 in cohort 3.

Discussion

A total of 3636 patients were enrolled until July 2018. The prospective disease registry will provide comprehensive and wide-ranging real-world information on how PC is diagnosed and treated in Asia. Such information can be used to inform policy development for best practice and direct clinical study design evaluating new treatments.

Potent Anti-Cancer Properties of Phthalimide-Based Curcumin Derivatives on Prostate Tumor Cells

Metastatic castration-resistant prostate cancer is commonly treated with chemotherapy, whose effect is less than satisfactory. This raised the need for novel agents for the treatment of prostate cancer. In the present study, five phthalimide-based curcumin derivatives were synthesized and completely characterized to assess improved stability, pharmacodynamics, and radical scavenging ability. To investigate the potential application in anti-cancer therapy, the anti-proliferative activity of the synthesized molecules was determined on aggressive prostate tumor cells. We demonstrated that the K3F21 derivative has increased potency compared to curcumin, in terms of GI50, anti-proliferative and anti-migrating activities. K3F21 inhibits anchorage-dependent and -independent growth of prostate cancer cells by altering the expression of key genes controlling cell proliferation, such as Cylins D1, B1 and B2, and apoptosis, among which Puma, Noxa, and Bcl-2 family members. Finally, the anti-cancer activity of K3F21 was demonstrated by the analysis of cancer-associated PI3K/AKT, ERK, and p38 signaling pathways.

Human ex vivo 3D bone model recapitulates osteocyte response to metastatic prostate cancer

Prostate cancer (PCa) is the second leading cause of cancer deaths among American men. Unfortunately, there is no cure once the tumor is established within the bone niche. Although osteocytes are master regulators of bone homeostasis and remodeling, their role in supporting PCa metastases remains poorly defined. This is largely due to a lack of suitable ex vivo models capable of recapitulating the physiological behavior of primary osteocytes. To address this need, we integrated an engineered bone tissue model formed by 3D-networked primary human osteocytes, with conditionally reprogrammed (CR) primary human PCa cells. CR PCa cells induced a significant increase in the expression of fibroblast growth factor 23 (FGF23) by osteocytes. The expression of the Wnt inhibitors sclerostin and dickkopf-1 (Dkk-1), exhibited contrasting trends, where sclerostin decreased while Dkk-1 increased. Furthermore, alkaline phosphatase (ALP) was induced with a concomitant increase in mineralization, consistent with the predominantly osteoblastic PCa-bone metastasis niche seen in patients. Lastly, we confirmed that traditional 2D culture failed to reproduce these key responses, making the use of our ex vivo engineered human 3D bone tissue an ideal platform for modeling PCa-bone interactions.

Corosolic acid, a natural triterpenoid, induces ER stress-dependent apoptosis in human castration resistant prostate cancer cells via activation of IRE-1/JNK, PERK/CHOP and TRIB3

Background

The development of potent non-toxic chemotherapeutic drugs against castration resistant prostate cancer (CRPC) remains a major challenge. Corosolic acid (CA), a natural triterpenoid, has anti-cancer activity with limited side effects. However, CA anti-prostate cancer activities and mechanisms, particularly in CRPC, are not clearly understood. In this study, we investigated CA anti-tumor ability against human CRPC and its mechanism of action.

Methods

The cell apoptosis and proliferation effects were evaluated via MTT detection, colony formation assay and flow cytometry. Western blot, gene transfection and immunofluorescence assay were applied to investigate related protein expression of Endoplasmic reticulum stress. A xenograft tumor model was established to investigate the inhibitory effect of CA on castration resistant prostate cancer in vivo.

Results

The results showed that CA inhibited cell growth and induced apoptosis in human prostate cancer cell (PCa) line PC-3 and DU145, as well as retarded tumor growth in a xenograft model, exerting a limited toxicity to normal cells and tissues. Importantly, CA activated endoplasmic reticulum (ER) stress-associated two pro-apoptotic signaling pathways, as evidenced by increased protein levels of typical ER stress markers including IRE-1/ASK1/JNK and PERK/eIF2α/ATF4/CHOP. IRE-1, PERK or CHOP knockdown partially attenuated CA cytotoxicity against PCa cells. Meanwhile, CHOP induced expression increased Tribbles 3 (TRIB3) level, which lead to AKT inactivation and PCa cell death. CHOP silencing resulted in PCa cells sensitive to CA-induced apoptosis.

Conclusion

Our data demonstrated, for the first time, that CA might represent a novel drug candidate for the development of an anti-CRPC therapy.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0889-x) contains supplementary material, which is available to authorized users.