Current and Emerging Therapies for Metastatic Castration-Resistant Prostate Cancer (mCRPC)

Prostate-Specific Membrane Antigen-Targeted Antibody-Drug Conjugates: A Promising Approach for Metastatic Castration-Resistant Prostate Cancer

Prostate cancer (PCa), especially metastatic castration-resistant prostate cancer (mCRPC), is a significant cancer characterized by its poor prognosis and limited treatment options. Prostate-specific membrane antigen (PSMA) has emerged as a diagnostic and therapeutic target for PCa due to its restricted expression in malignant prostate tissues. In this case, several PSMA-targeting molecules were developed for radiotherapy and immunotherapy. Antibody-drug conjugates (ADCs) are a novel therapeutic approach for various carcinomas that can selectively target PSMA-positive tumor cells and minimize off-target toxicity. ADCs have made great progress in the treatment of breast and bladder cancers, and some have received FDA approval for target therapy. However, studies on PSMA ADCs are limited, and most clinical trials are at stage I or II. Therefore, this study reviewed trials about PSMA-targeting ADCs for the treatment of PCa. Clinical trials have reported a favorable pharmacokinetic profile and antitumor activity. Toxicity studies have revealed manageable adverse effects, with no significant off-target toxicity in PSMA-negative tissues. This study highlights the therapeutic potential of PSMA ADCs for the treatment of mCRPC. However, it also emphasizes the necessity of further clinical investigation to optimize efficacy, safety, and patient outcomes.

A PSMA-Targeted Tri-Specific Killer Engager Enhances NK Cell Cytotoxicity against Prostate Cancer

NK cell tumor infiltration is associated with good prognosis in patients with metastatic castration-resistant prostate cancer (mCRPC). NK cells recognize and kill targets by a process called natural cytotoxicity. We hypothesized that promoting an antigen-specific synapse with coactivation may enhance NK cell function in mCRPC. We describe a tri-specific killer engager (TriKE) construct that engages with the activating receptor CD16 on NK cells and prostate-specific membrane antigen (PSMA) on mCRPC cells and has an IL15 moiety that is essential for NK cell survival, proliferation, and priming. We show that the PSMA TriKE specifically binds to PSMA-expressing cells and significantly enhances expansion, degranulation, and cytokine production of NK cells derived from healthy donors or patients with prostate cancer. Bystander killing of PSMA-negative tumor cells was also achieved with PSMA TriKE treatment when cocultured with PSMA-positive cells, suggesting potential PSMA TriKE benefit in controlling tumor antigen escape. When tested under physiologic conditions recapitulating the mCRPC tumor microenvironment, NK cells treated with PSMA TriKE and prolonged exposure to hypoxia or myeloid-derived suppressor cells maintained their potent function whereas IL15-treated NK cells showed greatly impaired cytotoxicity. Finally, in vivo testing of PSMA TriKE showed improved tumor control and survival of mice as compared with IL15-treated and untreated control groups. In conclusion, PSMA TriKE demonstrates potential as a new therapy for advanced prostate cancer by providing additional signals to NK cells to maximize their antitumor potential in prostate cancer, especially in the setting of a hostile tumor microenvironment.

DNA Repair Capacity and Clinicopathological Characteristics in Puerto Rican Hispanic/Latino Patients with Metastatic Castration-Resistant Prostate Cancer

BACKGROUND

Prostate cancer (PCa) accounts for 22% of the new cases diagnosed in Hispanic/Latino (H/L) men in the US. PCa has the highest incidence (38.3%) and mortality (16.4%) among all types of cancer diagnosed in Puerto Rico. We previously showed that PCa patients (n = 41) have a significant reduction of 59% in their levels of DNA repair capacity (DRC) when compared to controls (n = 14). This study aimed to evaluate DRC levels through the nucleotide excision repair (NER) pathway for the first time in 16 Puerto Rican H/L men with metastatic castration-resistant PCa (mCRPCa) while establishing comparisons with controls and PCa patients with indolent and aggressive disease.

METHODS

Blood samples and clinicopathological data from PCa cases (n = 71) and controls (n = 25) were evaluated. PCa cases were stratified into mCRPCa (n = 16), aggressive (n = 31), and indolent (n = 24). DRC levels through NER were measured in lymphocytes with the CometChip assay. The stratification by Gleason score (GS) was GS6 (n = 7), GS7 (n = 23), GS ≥ 8 (n = 20), and mCRPCa patients (n = 16).

RESULTS

Significant statistical differences were found when comparing the DRC values of the controls with any other of the four PCa patient groups. mCRPCa patients had the lowest mean DRC level of all four patient groups studied. The mean DRC level of mCRPCa patients was 6.65%, and compared to the controls, this represented a statistically significant reduction of 62% (p < 0.0001). Further analysis was performed to evaluate the contributions of age, anthropometric measurements, and prostate-specific antigen (PSA) levels to the DRC. Kaplan-Meier curves of mCRPCa revealed that survival probability decreased by approximately 50% by 30 months. This pilot study uses a blood-based phenotypic assay to present the first report of mCRPCa in Puerto Rican men and at a global level of DRC levels of mCRPCa patients.

CONCLUSIONS

This study evaluated DRC levels through the NER pathway for the first time in 16 Puerto Rican H/L men with mCRPCa. Significant differences in DRC values were found between the controls and the three PCa patient groups. Kaplan-Meier curves revealed that survival probability decreased by approximately 50% by 30 months, and only 20% of the cohort was alive at 50 months, confirming the lethality of mCRPCa in this H/L population. This pilot study represents the first report of metastatic PCa in Puerto Rican men at a global level of DRC levels of mCRPCa patients using a blood-based phenotypic assay.

Identifying MTHFD1 and LGALS4 as Potential Therapeutic Targets in Prostate Cancer Through Multi-Omics Mendelian Randomization Analysis

Background: Prostate cancer remains one of the leading causes of cancer-related mortality in men worldwide. The treatment of it is currently based on surgical removal, radiotherapy, and hormone therapy. It is crucial to improve therapeutic prospects for the diagnosis and treatment of prostate cancer via drug target screening. Methods: We integrated eQTL data from the eQTLGen Consortium and pQTL data from UK Biobank Proteome Plasma Proteins (UKB-PPP) and deCODE health datasets. MR analyses (SMR, heterogeneity in dependent instruments (HEIDI), IVW, Wald ratio, weighted median, and MR-Egger) were used to screen candidate genes associated with prostate adenocarcinoma (PRAD) risk. Candidate genes were further verified through TCGA-based gene expression profile, survival analysis, and immune microenvironment evaluations. TIDE analysis was utilized to investigate gene immunotherapy response. Single-cell RNA sequencing data from the GSE176031 dataset were used to investigate the gene expression patterns. The Drug Bank, Therapeutic Target Database and Drug Signatures Database were utilized to predict targeted drugs for candidate genes. Results: MTHFD1 and LGALS4 were identified as promising therapeutic targets for PRAD, with evidence provided at multi-omics levels. LGALS4 was predominantly expressed in malignant cells and was correlated with enhanced immune checkpoint pathways, increased TIDE scores, and immunotherapy resistance. In contrast, MTHFD1was expressed in both tumor and microenvironmental cells and was associated with poor survival. Drug target prediction suggested that there are no currently approved drugs specifically targeting MTHFD1 and LGALS4. Conclusions: Our study identified MTHFD1 and LGALS4 as potential preventive targets for PRAD. However, future experiments are warranted to assess the utility and effectiveness of these candidate proteins.

Bone health management in endocrine-treated patients with prostate cancer: a summary of evidence

OBJECTIVE

This study aimed to gather and assess the most reliable evidence on bone health management in patients undergoing endocrine therapy for prostate cancer, with the goal of informing clinical practice.

DESIGN AND METHODS

Utilizing the '6S' evidence model, a comprehensive literature search was conducted across various sources such as computerized decision support systems, national and international guideline networks, society websites, and databases encompassing clinical decision-making, guidelines, systematic reviews, evidence summaries, and expert consensus. The search spanned from April 2014 to April 2024, with two researchers independently evaluating the quality of the identified literature.

RESULTS

A total of 12 articles were included, comprising 6 clinical guidelines, 5 expert consensus papers, and 1 systematic evaluation. The findings were categorized into risk assessment, prevention, and interventions for osteoporosis and fractures, yielding 26 pieces of best evidence.

CONCLUSION

This study synthesized key evidence on bone health management for prostate cancer patients undergoing endocrine therapy, emphasizing the importance of healthcare professionals utilizing this evidence to develop and implement effective bone health management strategies to mitigate the risk of osteoporosis and fractures.

Prognostic value of baseline alkaline phosphatase of 177Lu-PSMA radioligand therapy in metastatic castration-resistant prostate cancer: A systematic review and meta-analysis

BACKGROUND

Current studies have shown inconsistent results regarding the impact of baseline alkaline phosphatase (ALP) levels on the prognosis of metastatic castration-resistant prostate cancer (mCRPC) patients who undergo 177Lu-prostate-specific membrane antigen (PSMA) radioligand therapy (PRLT). Therefore, a comprehensive meta-analysis is needed to clarify the implications.

METHODS

This study was carried out in full compliance with the PRISMA protocol 2020, and a comprehensive search was conducted through PubMed, Web of Science, and Embase for published literature up to April 1st, 2024. Random-effects models were used to assess the correlation between baseline ALP and overall survival (OS) or progression-free survival (PFS) of mCRPC patients treated with 177Lu-PRLT, with a significance level set at α = 0.05.

RESULTS

A total of 12 articles were included in this study. The pooled effect estimates for baseline ALP and OS were 1.134 (95% CI: 1.035-1.245), I2 = 78.7%, P < 0.05. Regarding baseline ALP and PFS, the pooled effect estimate was found to be 2.14 (95% CI: 1.232-3.718), I2 = 93.3%, P < 0.05. Subgroup analysis revealed minimal heterogeneity among articles using a cut-off value ≥220U/L when examining the association between baseline ALP and OS; whereas for baseline ALP and PFS, there was also minimal heterogeneity observed among articles that adjusted for confounders.

CONCLUSION

This meta-analysis demonstrates a significant association between elevated baseline ALP levels in mCRPC patients prior to 177Lu-PRLT treatment and inferior OS and PFS. Timely monitoring of baseline ALP levels can provide valuable insights for clinical decision-making and patient counseling.

Highly efficient nucleic acid encapsulation method for targeted gene therapy using antibody conjugation system

Gene therapy has surfaced as a promising avenue for treating cancers, offering the advantage of deliberate adjustment of targeted genes. Nonetheless, the swift degradation of nucleic acids in the bloodstream necessitates an effective and secure delivery system. The widespread utilization of poly(lactic-co-glycolic acid) (PLGA) nanoparticles as drug delivery systems has highlighted challenges in controlling particle size and release properties. Moreover, the encapsulation of nucleic acids exacerbates these difficulties due to the negatively charged surface of PLGA nanoparticles. In this study, we aimed to improve the encapsulation efficiency of nucleic acids by employing negatively charged microbeads and optimizing the timing of the specific formulation steps. Furthermore, by conjugating PSMA-617, a ligand for the prostate-specific membrane antigen (PSMA), with PLGA nanoparticles, we assessed the antitumor effects and the efficacy of a nucleic acid delivery system on a prostate cancer model. The employed technique within the nucleic acid encapsulation system represents a novel approach that could be adapted to encapsulate various kinds of nucleic acids. Moreover, it enables the attachment of targeting moieties to different cell membrane proteins, thereby unveiling new prospects for precise therapeutics in cancer therapy.

Real-world efficacy and safety of combined first-line treatment with PARP inhibitors and novel hormonal therapy in mCRPC patients with HRR gene mutations

Objective

This study evaluated the real-world efficacy and safety of combining PARP inhibitors with novel hormonal therapy (NHT) as a first-line treatment in Chinese patients with metastatic castration-resistant prostate cancer (mCRPC) harboring homologous recombination repair (HRR) gene mutations.

Methods

We enrolled 41 mCRPC patients who received at least 1 month of combined treatment with PARP inhibitors and NHT. Patients were divided into two groups: Cohort A (mutations in BRCA1, BRCA2, or ATM genes) and Cohort B (mutations in other HRR genes). The primary endpoint was imaging-based progression-free survival (PFS), with secondary endpoints including objective response rate (ORR), disease control rate (DCR), overall survival (OS), PSA50 response, and adverse events (AEs). To ensure accurate research results and control confounding factors, we will employ multivariate Cox proportional hazards models to evaluate key variables affecting mCRPC patient survival outcomes.

Results

This study enrolled 41 patients, 22 in Cohort A and 19 in Cohort B. The median PFS for all patients was 21.8 months, and the median OS had yet to be reached. The overall ORR was 48.8%, and the DCR was 61.0%. Specifically, the median PFS for Cohort A was 21.8 months compared to 14.5 months for Cohort B. The median OS had yet to be reached for either cohort. Regarding efficacy, 81.8% of patients in Cohort A and 73.7% in Cohort B achieved a PSA50 response. Imaging assessments showed ORRs of 54.6% for Cohort A and 42.1% for Cohort B, with DCRs of 72.7% and 47.4%, respectively. 85.4% of patients experienced grade 1 or 2 adverse events, and 51.2% encountered grade 3 or 4. In the multivariate Cox regression analysis focusing on PFS, the Gleason score was identified as a significant predictor (HR = 5.8, 95% CI: 1.65-20.2, p = 0.006).

Conclusion

Combined first-line treatment with PARP inhibitors and NHT is effective and well-tolerated in mCRPC patients with HRR gene mutations, particularly those with BRCA1, BRCA2, or ATM mutations. These findings underscore the potential of this therapeutic combination in managing mCRPC in the Chinese population, suggesting a favorable outcome for those with specific genetic backgrounds.

Progression-directed Therapy in Oligoprogressive Castration-resistant Prostate Cancer: Final Results from the Prospective, Single-arm, Phase 2 MEDCARE Trial

BACKGROUND AND OBJECTIVE

Next-line systemic treatment (NEST) is the standard of care for patients presenting with progressive metastatic castration-resistant prostate cancer (mCRPC). Progression-directed therapy (PDT), defined as a lesion-directed approach in patients with a limited number of progressive and/or new lesions, could postpone the need for NEST in these patients with so-called oligoprogressive mCRPC. Our aim was to investigate the feasibility of postponing NEST initiation in oligoprogressive mCRPC by using PDT.

METHODS

MEDCARE was a prospective, single-arm, nonrandomized phase 2 trial. Eligible patients had oligoprogressive mCRPC and were treated with PDT while their ongoing systemic therapy was continued. The primary endpoint was NEST-free survival (NEST-FS). Secondary endpoints were prostate-specific antigen response, clinical progression-free survival (cPFS), prostate cancer-specific survival (PCSS), overall survival (OS), and PDT-induced toxicity.

KEY FINDINGS AND LIMITATIONS

Twenty patients underwent PDT for 38 oligoprogressive lesions. At median follow-up of 28 mo, median NEST-FS was 17 mo and the 2-yr NEST-FS rate was 35%. Median PCSS and median OS were not reached. The PCSS and OS rates at 2 yr were 80% and 70%, respectively. The 2-yr local control rate was 95%. No patient experienced early or late grade ≥3 toxicity. NEST-FS was longer for patients who received PDT to all lesions visible on 18F-PSMA positron emission tomography/computed tomography (30 vs 13 mo; p = 0.002).

CONCLUSIONS AND CLINICAL IMPLICATIONS

This single-center, single-arm, phase 2 trial demonstrated that PDT in oligoprogressive mCRPC resulted in median NEST-FS of 17 mo without any early or late grade ≥3 toxicity.

PATIENT SUMMARY

For patients with metastatic prostate cancer no longer responding to hormone therapy, we investigated radiotherapy targeted at progressive cancer lesions while continuing their ongoing systemic treatment. The results show that this targeted therapy had very low toxicity and delayed the need to start a new line of systemic treatment by 17 months.

Efficacy and Safety of Combination AKT and Androgen Receptor Signaling Inhibition in Metastatic Castration-Resistant Prostate Cancer: Systematic Review and Meta-Analysis

BACKGROUND

Metastatic castration-resistant prostate cancer (mCRPC) has a poor prognosis with current treatment options including chemotherapy and androgen receptor signaling inhibitor (ARSI) medications. Poly-ADP ribose polymerase (PARP) inhibitors alone and in combination with ARSI has recently been incorporated in management for mCRPC deficient in BRCA1/2 genes. However, downregulating androgen-receptor signaling using ARSIs can upregulate the PI3K/AKT/mTOR pathway, promoting tumor cell survival. This creates a rationale for co-targeting both these pathways. This systematic review aimed to investigate AKT inhibitors and ARSI combination therapy.

METHODS

EMBASE, MEDLINE, and Scopus were searched from database inception to July 2023. Primary outcomes included objective response rate (ORR), prostate-specific antigen (PSA) response rate, adverse events (AEs), overall survival (OS), and radiographic progression-free survival (rPFS). Quality was assessed using the risk of bias tool (ROB2) and certainty of evidence with GRADE.

RESULTS

Six clinical trials with 3 Phase I, 1 Phase II, 1 Phase III were included with 771 patients and a median age ranging from 67 years to 70 years. The pooled ORR was 30% (n = 5 studies, 95% CI, 3%-84%) and PSA response rate was 43% (n = 5 studies, 95% CI, 15%-77%). The median duration of rPFS ranged from 8.2 to 19.2 months in the intervention compared with 6.4 to 16.6 months in the placebo group. A 16% reduction in radiographic progression or death was reported in patients receiving dual therapy compared with those receiving placebo. This reduction was greater by PTEN-loss status, ranging from 23% to 61%. The median OS ranged from 15.6 to 18.9 months. No significant difference was reported in survival relative to placebo. 98.8% (767/776) of patients experienced AEs of any grade, with GRADE ≥3 AEs occurring in 65.9% (512/776) of patients. The most common AE and GRADE ≥3 AEs were diarrhoea (pooled prevalence = 70%, 95% CI, 57%-81%), and hyperglycaemia (pooled prevalence = 12%, 95% CI, 6%-20%), respectively.

CONCLUSION

Combined therapy reduced the risk of rPFS, with the response higher in PTEN-loss subgroup, with a modest but not significant increase in OS. Our AE estimates showed consistency with other studies. AEs of any grade were common with the majority experiencing at least 1 AE. (PROSPERO Registration Number: CRD420202352583).

An evaluation of talazoparib plus enzalutamide for the treatment of metastatic castration-resistant prostate cancer

INTRODUCTION

Prostate cancer (PCa) is the second most common cancer diagnosis among men worldwide, with poor prognosis in its advanced stage. Treatment strategies have evolved, including the use of androgen receptor pathway inhibitors (ARPIs) and poly (ADP-ribose) polymerase inhibitors (PARPis).

AREAS COVERED

This review evaluates the clinical efficacy, safety, and future potential of combining talazoparib, a potent PARPi, with enzalutamide, a strong androgen receptor (AR) antagonist. The combination of these two drugs was evaluated by the TALAPRO-2 trial, demonstrating significant improvement in radiographic progression-free survival (rPFS) in metastatic castration-resistant prostate cancer (mCRPC) patients, particularly those with Homologous Recombination Repair (HRR) gene mutations such as BRCA1/2.

EXPERT OPINION

Emerging biomarkers like TMPRSS2-ERG and RB1 gene mutations have been recently reported as potential predictors of clinical outcome in the TALAPRO-2 all-comers population. Genomic markers for homologous recombination deficiency (HRD) are other potential drivers of response to PARPi/ARPI combination. Further investigation is needed to refine treatment strategies, including targeting non-HRR mutations, and to expand the role of this combination therapy in earlier stages of prostate cancer.

A Prostate-Specific Membrane Antigen-Targeting Small Molecule-Drug Conjugate Strategy to Overcome the Hematological Toxicity of Olaparib

PARP inhibitors have gained attention in the treatment of metastatic castration-resistant prostate cancer, but approximately half of patients have to abort treatment due to severe hematological toxicity. Herein, we proposed a prostate-specific membrane antigen (PSMA)-targeting small molecule-drug conjugate (SMDC) strategy to address this issue. This led to CQ-16, which achieved its targeting to prostate tumor cells through binding to PSMA. Also, CQ-16 retained the PARP inhibitory activity and exhibited highly selective antiproliferative activities between PSMA-positive and PSMA-negative prostate cells. Moreover, the hematological toxicity observed in Olaparib was not showing in the group of CQ-16 even at a high dose of 390 mg/kg. Moreover, oral administration of CQ-16 exerted significant tumor growth inhibition in the 22Rv1 xenograft mouse model. These above findings not only highlight the potential of CQ-16 to overcome the hematological toxicity associated with PARP inhibitors but also provide a strategy to develop an SMDC with enhanced safety profiles.

Performance Status and End-of-Life Outcomes in Patients With Metastatic Castration-resistant Prostate Cancer Treated With Androgen Receptor Targeted Therapy

OBJECTIVES

Androgen receptor targeted therapies (ARTs) are widely preferred over taxane chemotherapy due to their good tolerability and similar efficacy. However, there is a paucity of data that support the use of ART therapy or describe end-of-life (EOL) outcomes in patients with metastatic castration-resistant prostate cancer (mCRPC) with reduced performance status (PS) (European Cooperative Oncology Group [ECOG] ≥2).

METHODS

We performed a retrospective, single-institution study of 142 patients with mCRPC who received ART therapy between 2010 and 2021. We assessed each record for baseline demographic and clinical information, ART treatment course, and survival and EOL outcomes. Our primary aim was to compare overall survival (OS) between the two groups (ECOG ≥2 vs 0 to 1), and our secondary aim was to describe EOL outcomes. Fisher exact tests and Wilcoxon signed-rank tests were used to compare baseline characteristics. Cox regression was used to compare OS for patients with ECOG ≥2 at the start of treatment with those who had an ECOG of 0 or 1. Descriptive analyses were performed to assess EOL outcomes between the groups.

RESULTS

Patients with mCRPC and decreased PS experienced shorter OS on ART compared with those with higher PS. Moreover, when examining EOL outcomes, a near majority of these patients died in the hospital, with a greater percentage among those with an ECOG ≥2.

CONCLUSION

These findings highlight the need for continual assessment of PS, improved shared decision-making in ART treatment, and additional research exploring the association between PS and EOL outcomes.

Pharmacokinetics, Mass Balance, and Biotransformation of [14C]tinengotinib, A Novel Multi-target Kinase Inhibitor, in Healthy Subjects

BACKGROUND AND OBJECTIVE

Tinengotinib, a novel multi-target small molecule kinase inhibitor, is currently undergoing phase II clinical trial in the USA and China. The purpose of this open-label study was to investigate the absorption, metabolism, and excretion of [14C]tinengotinib following a single oral dose in healthy subjects.

METHODS

Six healthy male subjects received a single oral dose of [14C]tinengotinib capsules at 10 mg/100 µCi, and blood, urine, and feces samples were collected. Phenotyping experiments were further conducted to confirm the enzymes involved in its metabolism.

RESULTS

Tinengotinib was rapidly absorbed in plasma with a time to peak drug concentration (Tmax) of 1.0-4.0 h post-dose and a long terminal half-life (t½) of 23.7 h. Blood-to-plasma radioactivity concentration ratios across timepoints ranged from 0.780 to 0.827, which indicated minimal association of radioactivity with blood cells. The mean cumulative excreted radioactivity was 99.57% of the dose, including 92.46% (68.65% as unchanged) in feces and 7.11% (0.28% as unchanged) in urine. In addition to unchanged tinengotinib, a total of 11 radioactive metabolites were identified in plasma, urine, and feces. The most abundant circulating radioactivity was the parent drug in plasma, which comprised 88.23% of the total radioactivity area under the concentration-time curve (AUC). Metabolite M410-3 was a major circulating metabolite, accounting for 5.38% of the parent drug exposure and 4.75% of the total drug-related exposure, respectively. All excreted metabolites accounted for less than 5.10% and 1.82% of the dose in feces and urine, respectively. In addition, no unique metabolites were observed in humans. Tinengotinib was metabolized mainly via CYP3A4.

CONCLUSIONS

Overall, tinengotinib demonstrated a complete mass balance with limited renal excretion, no disproportionate blood metabolism, and slow elimination, primarily through the fecal route. The results of this study provide evidence to support the rational use of tinengotinib as a pharmacotherapeutic agent.

REGISTRATION

ChinadrugTrials.org.cn identifier: CTR20212852.

Adjustment for imbalances in baseline characteristics in the MAGNITUDE phase 3 study confirms the clinical benefit of niraparib in combination with abiraterone acetate plus prednisone in patients with metastatic prostate cancer

BACKGROUND

MAGNITUDE (NCT03748641) demonstrated favourable outcomes with niraparib plus abiraterone acetate plus prednisone (+AAP) versus placebo+AAP in patients with BRCA1/2-altered metastatic castration-resistant prostate cancer (mCRPC). Imbalances in prognostic variables were reported between arms, which impacts estimation of both the clinical benefit and cost‑effectiveness of niraparib+AAP for healthcare systems. A pre-specified multivariable analysis (MVA) demonstrated improved overall survival (OS) with niraparib+AAP. Here, we used an inverse probability of treatment weighting (IPTW) model to adjust for covariate imbalances and assess time-to-event outcomes.

METHODS

IPTW analysis of time-to-event outcomes was conducted using data from patients with BRCA1/2-altered mCRPC (N = 225) in MAGNITUDE. Patients received niraparib+AAP or placebo+AAP. OS, radiographic progression-free survival, time to symptomatic progression, time to initiation of cytotoxic chemotherapy and time to prostate-specific antigen progression were assessed. Weighted Kaplan-Meier curves were generated for each endpoint, and adjusted hazard ratios (HR) were obtained from a weighted Cox model.

RESULTS

Improvements in survival outcomes were estimated for niraparib+AAP versus placebo+AAP: unadjusted median OS was 30.4 months versus 28.6 months, respectively (HR: 0.79; 95 % confidence interval [CI]: 0.55, 1.12; p = 0.183). Following IPTW, median OS increased to 34.1 months with niraparib+AAP versus a decrease to 27.4 with placebo (HR: 0.65; 95 % CI: 0.46, 0.93; p = 0.017). Similar improvements were observed for other time-to-event endpoints.

CONCLUSIONS

IPTW adjustment provided a more precise estimate of the clinical benefit of niraparib+AAP versus placebo+AAP in patients with BRCA1/2-altered mCRPC. Results were consistent with the pre-specified MVA, and further demonstrated the value of adjusting for baseline imbalances, particularly in smaller studies.

TRIAL REGISTRATION

NCT03748641 (MAGNITUDE).

Cancer-associated fibroblasts and prostate cancer stem cells: crosstalk mechanisms and implications for disease progression

The functional heterogeneity and ecological niche of prostate cancer stem cells (PCSCs), which are major drivers of prostate cancer development and treatment resistance, have attracted considerable research attention. Cancer-associated fibroblasts (CAFs), which are crucial components of the tumor microenvironment (TME), substantially affect PCSC stemness. Additionally, CAFs promote PCSC growth and survival by releasing signaling molecules and modifying the surrounding environment. Conversely, PCSCs may affect the characteristics and behavior of CAFs by producing various molecules. This crosstalk mechanism is potentially crucial for prostate cancer progression and the development of treatment resistance. Using organoids to model the TME enables an in-depth study of CAF-PCSC interactions, providing a valuable preclinical tool to accurately evaluate potential target genes and design novel treatment strategies for prostate cancer. The objective of this review is to discuss the current research on the multilevel and multitarget regulatory mechanisms underlying CAF-PCSC interactions and crosstalk, aiming to inform therapeutic approaches that address challenges in prostate cancer treatment.

Metastatic Castration-Resistant Prostate Cancer: Advances in Treatment and Symptom Management

OPINION STATEMENT

The management of metastatic castrate-resistant prostate cancer (mCRPC) has evolved in the past decade due to substantial advances in understanding the genomic landscape and biology underpinning this form of prostate cancer. The implementation of various therapeutic agents has improved overall survival but despite the promising advances in therapeutic options, mCRPC remains incurable. The focus of treatment should be not only to improve survival but also to preserve the patient's quality of life (QoL) and ameliorate cancer-related symptoms such as pain. The choice and sequence of therapy for mCRPC patients are complex and influenced by various factors, such as side effects, disease burden, treatment history, comorbidities, patient preference and, more recently, the presence of actionable genomic alterations or biomarkers. Docetaxel is the first-line treatment for chemo-naïve patients with good performance status and those who have yet to progress on docetaxel in the castration-sensitive setting. Novel androgen agents (NHAs), such as abiraterone and enzalutamide, are effective treatment options that are utilized as second-line options. These medications can be considered upfront in frail patients or patients who are NHA naïve. Current guidelines recommend genetic testing in mCRPC for mutations in DNA repair deficiency genes to inform treatment decisions, as for example in breast cancer gene mutation testing. Other potential biomarkers being investigated include phosphatase and tensin homologues and homologous recombination repair genes. Despite a growing number of studies incorporating biomarkers in their trial designs, to date, only olaparib in the PROFOUND study and lutetium-177 in the VISION trial have improved survival. This is an unmet need, and future trials should focus on biomarker-guided treatment strategies. The advent of novel noncytotoxic agents has enhanced targeted drug delivery and improved treatment responses with favourable toxicity profiling. Trials should continue to incorporate and report health-related QoL scores and functional assessments into their trial designs.

Pentagalloyl Glucose (PGG) Exhibits Anti-Cancer Activity against Aggressive Prostate Cancer by Modulating the ROR1 Mediated AKT-GSK3β Pathway

Androgen-receptor-negative, androgen-independent (ARneg-AI) prostate cancer aggressively proliferates and metastasizes, which makes treatment difficult. Hence, it is necessary to continue exploring cancer-associated markers, such as oncofetal Receptor Tyrosine Kinase like Orphan Receptor 1 (ROR1), which may serve as a form of targeted prostate cancer therapy. In this study, we identify that Penta-O-galloyl-β-D-glucose (PGG), a plant-derived gallotannin small molecule inhibitor, modulates ROR1-mediated oncogenic signaling and mitigates prostate cancer phenotypes. Results indicate that ROR1 protein levels were elevated in the highly aggressive ARneg-AI PC3 cancer cell line. PGG was selectively cytotoxic to PC3 cells and induced apoptosis of PC3 (IC50 of 31.64 µM) in comparison to normal prostate epithelial RWPE-1 cells (IC50 of 74.55 µM). PGG was found to suppress ROR1 and downstream oncogenic pathways in PC3 cells. These molecular phenomena were corroborated by reduced migration, invasion, and cell cycle progression of PC3 cells. PGG minimally and moderately affected RWPE-1 and ARneg-AI DU145, respectively, which may be due to these cells having lower levels of ROR1 expression in comparison to PC3 cells. Additionally, PGG acted synergistically with the standard chemotherapeutic agent docetaxel to lower the IC50 of both compounds about five-fold (combination index = 0.402) in PC3 cells. These results suggest that ROR1 is a key oncogenic driver and a promising target in aggressive prostate cancers that lack a targetable androgen receptor. Furthermore, PGG may be a selective and potent anti-cancer agent capable of treating ROR1-expressing prostate cancers.

From Despair to Hope: First Arabic Experience of 177Lu-PSMA and 161Tb-PSMA Therapy for Metastatic Castration-Resistant Prostate Cancer

The objective of this retrospective study is to assess the effectiveness and safety of two beta-emitting prostate-specific membrane antigen (PSMA) radioligands, [177Lu]Lu and [161Tb]Tb, in heavily treated patients with metastatic castration-resistant prostate cancer (mCRPC). A total of 148 cycles of beta-emitting PSMA radioligand therapy were given to 53 patients at a specialized cancer care center in Amman, Jordan. This treatment was offered following the exhaustion of all prior treatment modalities. Approximately half of the cases (n = 26) demonstrated an initial partial response to PSMA radioligand therapy. Moreover, roughly one-fourth of the patients (n = 13) exhibited a sustained satisfactory biochemical response, which qualified them to receive a total of six PSMA radioligand therapy cycles and maintain continued follow-up for additional treatment cycles. This was reflected by an adequate prostate-specific antigen (PSA) decline and a concomitant partial response evident on [68Ga]Ga-PSMA positron emission tomography/computed tomography imaging. A minority of patients (n= 18; 34%) experienced side effects. Generally, these were low-grade and self-limiting toxicities. This study endorses previous research evidence about PSMA radioligand therapy's safety and efficacy. It also provides the first clinical insight from patients of Arab ethnicity. This should facilitate and promote further evidence, both regionally and internationally.

Nanocarrier - Mediated Salinomycin Delivery Induces Apoptosis and Alters EMT Phenomenon in Prostate Adenocarcinoma

Salinomycin (Sal) has been recently discovered as a novel chemotherapeutic agent against various cancers including prostate cancer which is one of the most commonly diagnosed cancers affecting male populations worldwide. Herein we designed salinomycin nanocarrier (Sal-NPs) to extend its systemic circulation and to increase its anticancer potential. Prepared nanoform showed high encapsulation and sustained release profile for salinomycin. The present study elucidated the cytotoxicity and mechanism of apoptotic cell death of Sal-NPs against prostate cancer both in vitro and in vivo. At all measured concentrations, Sal-NPs showed more significant cytotoxicity to DU145 and PC3 cells than Sal alone. This effect was mediated by apoptosis, as confirmed by ROS generation, loss of MMP and cell cycle arrest at the G1 phase in both cells. Sal-NPs efficiently inhibited migration of PC3 and DU145 cells via effectively downregulating the epithelial mesenchymal transition. Also, the results confirmed that Sal-NPs can effectively inhibit the induction of Prostate adenocarcinoma in male Wistar rats. Sal-NPs treatment exhibited a decrease in tumour sizes, a reduction in prostate weight, and an increase in body weight, which suggests that Sal-NPs is more effective than salinomycin alone. Our results suggest that the molecular mechanism underlying the Sal-NPs anticancer effect may lead to the development of a potential therapeutic strategy for treating prostate adenocarcinoma.

First-line combination treatment with PARP and androgen receptor-signaling inhibitors in HRR-deficient mCRPC: Applying clinical study findings to clinical practice in the United States

INTRODUCTION

Metastatic castration-resistant prostate cancer (mCRPC) remains incurable and develops from biochemically recurrent PC treated with androgen deprivation therapy (ADT) following definitive therapy for localized PC, or from metastatic castration-sensitive PC (mCSPC). In the mCSPC setting, treatment intensification of ADT plus androgen receptor (AR)-signaling inhibitors (ARSIs), with or without chemotherapy, improves outcomes vs ADT alone. Despite multiple phase 3 trials demonstrating a survival benefit of treatment intensification in PC, there remains high use of ADT monotherapy in real-world clinical practice. Prior studies indicate that co-inhibition of AR and poly(ADP-ribose) polymerase (PARP) may result in enhanced benefit in treating tumors regardless of alterations in DNA damage response genes involved either directly or indirectly in homologous recombination repair (HRR). Three recent phase 3 studies evaluated the combination of a PARP inhibitor (PARPi) with an ARSI as first-line treatment for mCRPC: TALAPRO-2, talazoparib plus enzalutamide; PROpel, olaparib plus abiraterone acetate and prednisone (AAP); and MAGNITUDE, niraparib plus AAP. Results from these studies have led to the recent approval in the United States of talazoparib plus enzalutamide for the treatment of mCRPC with any HRR alteration, and of both olaparib and niraparib indicated in combination with AAP for the treatment of mCRPC with BRCA alterations.

SUMMARY

Here, we review the newly approved PARPi plus ARSI treatments within the context of the mCRPC treatment landscape, provide an overview of practical considerations for the combinations in clinical practice, highlight the importance of HRR testing, and discuss the benefits of treatment intensification for patients with mCRPC.

Cardiovascular events among patients with prostate cancer treated with abiraterone and enzalutamide

BACKGROUND AND PURPOSE

There is growing concern about the adverse metabolic and cardiovascular effects of abiraterone acetate (AA) and enzalutamide (ENZ), two standard hormonal therapies for prostate cancer. We analysed the risk of cardiovascular adverse events among patients treated with AA and ENZ.

PATIENTS AND METHODS

We used Kythera Medicare data from January 2019 to June 2023 to identify patients with at least one pharmacy claim for AA or ENZ. The index date was the first prescription claim date. Patients were required to have 1 year of data pre- and post-index date. New users excluded those with prior AA or ENZ claims and pre-existing cardiovascular comorbidities. Demographic and clinical variables, including age, socioeconomic status (SES), comorbidity score, prostate-specific comorbidities, and healthcare costs, were analysed . Propensity score matching was employed for risk adjustment.

RESULTS

Of the 8,929 and 8,624 patients in the AA and ENZ cohorts, respectively, 7,647 were matched after adjusting for age, sociodemographic, and clinical factors. Between the matched cohorts (15.54% vs. 14.83%, p < 0.05), there were no statistically significant differences in any cardiovascular event after adjusting for these factors. The most common cardiovascular event in both cohorts was heart failure (5.20% vs. 4.49%), followed by atrial fibrillation (4.42% vs. 3.60%) and hypotension (2.93% vs. 2.48%).

INTERPRETATION

This study provides real-world evidence of the cardiovascular risk of AA and ENZ that may not appear in clinical trial settings. Adjusting for age, baseline comorbidities, and SES, the likelihood of a cardiovascular event did not differ between treatment groups.

A phase 2 study of AZD4635 in combination with durvalumab or oleclumab in patients with metastatic castration-resistant prostate cancer

BACKGROUND

Inhibition of the adenosine 2A receptor (A2AR) diminishes the immunosuppressive effects of adenosine and may complement immune-targeting drugs. This phase 2 study evaluated the A2AR antagonist AZD4635 in combination with durvalumab or oleclumab in patients with metastatic castration-resistant prostate cancer.

METHODS

Patients with histologically/cytologically confirmed disease progressing within 6 months on ≥ 2 therapy lines were randomly assigned to either Module 1 (AZD4635 + durvalumab) or Module 2 (AZD4635 + oleclumab). Primary endpoints were objective response rate per RECIST v1.1 and prostate-specific antigen (PSA) response rate. Secondary endpoints included radiological progression-free survival (rPFS), overall survival, safety, and pharmacokinetics.

RESULTS

Fifty-nine patients were treated (Module 1, n = 29; Module 2, n = 30). Median number of prior therapies was 4. One confirmed complete response by RECIST (Module 1) and 2 confirmed PSA responses (1 per module) were observed. The most frequent adverse events (AEs) possibly related to AZD4635 were nausea (37.9%), fatigue (20.7%), and decreased appetite (17.2%) in Module 1; nausea (50%), fatigue (30%), and vomiting (23.3%) in Module 2. No dose-limiting toxicities or treatment-related serious AEs were observed. In Module 1, AZD4635 geometric mean trough concentration was 124.9 ng/mL (geometric CV% 69.84; n = 22); exposures were similar in Module 2. In Modules 1 and 2, median (95% CI) rPFS was 2.3 (1.6 -3.8) and 1.5 (1.3- 4.0) months, respectively. Median PFS was 1.7 versus 2.3 months for patients with high versus low blood-based adenosine signature.

CONCLUSION

In this heavily pretreated population, AZD4635 with durvalumab or oleclumab demonstrated minimal antitumor activity with a manageable safety profile.

CLINICAL TRIAL

gov identifier: NCT04089553.

Preparation, Optimization, and In-Vitro Evaluation of Brusatol- and Docetaxel-Loaded Nanoparticles for the Treatment of Prostate Cancer

Challenges to docetaxel use in prostate cancer treatment include several resistance mechanisms as well as toxicity. To overcome these challenges and to improve the therapeutic efficacy in heterogeneous prostate cancer, the use of multiple agents that can destroy different subpopulations of the tumor is required. Brusatol, a multitarget inhibitor, has been shown to exhibit potent anticancer activity and play an important role in drug response and chemoresistance. Thus, the combination of brusatol and docetaxel in a nanoparticle platform for the treatment of prostate cancer is expected to produce synergistic effects. In this study, we reported the development of polymeric nanoparticles for the delivery of brusatol and docetaxel in the treatment of prostate cancer. The one-factor-at-a-time method was used to screen for formulation and process variables that impacted particle size. Subsequently, factors that had modifiable effects on particle size were evaluated using a 24 full factorial statistical experimental design followed by the optimization of drug loading. The optimization of blank nanoparticles gave a formulation with a mean size of 169.1 nm ± 4.8 nm, in agreement with the predicted size of 168.333 nm. Transmission electron microscopy showed smooth spherical nanoparticles. The drug release profile showed that the encapsulated drugs were released over 24 h. Combination index data showed a synergistic interaction between the drugs. Cell cycle analysis and the evaluation of caspase activity showed differences in PC-3 and LNCaP prostate cancer cell responses to the agents. Additionally, immunoblots showed differences in survivin expression in LNCaP cells after treatment with the different agents and formulations for 24 h and 72 h. Therefore, the nanoparticles are potentially suitable for the treatment of advanced prostate cancer.

A Rare Case of Neuroendocrine Prostate Cancer Detected on 68Ga - DOTANOC Positron Emission Tomography/Computed Tomography (PET/CT)

Prostate cancer is one of the most common malignancies affecting elderly men worldwide and the fifth leading cause of cancer death in men. Prostate cancer includes many histological variants with the prostatic acinar adenocarcinoma variant accounting for the majority of the diagnosed cases. Other less common histological variants are broadly classified as non-acinar carcinomas. One of the non-acinar carcinoma variants is neuroendocrine prostate cancer (NEPC). NEPC can emerge as a mechanism of treatment resistance in castration-resistant conventional prostate cancer and can also rarely be seen as a primary histological form at the time of initial diagnosis. Like other non-acinar carcinoma variants of prostate cancer, NEPC is also an aggressive variant with associated poor prognosis. Neuroendocrine tumors (NETs) are characterized by the expression of somatostatin receptors (SSTRs). Positron emission tomography/computed tomography (PET/CT) using radiolabeled somatostatin analogs like DOTANOC have been used to detect and stage these NETs. These radiolabeled somatostatin analogs also provide the option of treatment of these tumors and have been used in peptide receptor radionuclide therapy of these tumors. NEPC being a neuroendocrine malignancy also expresses SSTRs and hence can be detected with PET/CT radiotracers like 68Gallium-labeled somatostatin analogs. We here report a case of metastatic treatment-emergent NEPC detected on 68Ga - DOTANOC PET/CT.

Receptor tyrosine kinase-like orphan receptor 1 inhibitor strictinin exhibits anti-cancer properties against highly aggressive androgen-independent prostate cancer

Aim

It is important to identify anti-cancer compounds that can inhibit specific molecular targets to eradicate androgen-receptor negative (ARneg), androgen-independent (AI) prostate cancer, which is an aggressive form of prostate cancer with limited treatment options. The goal of this study was to selectively target prostate cancer cells that have high levels of oncogenic protein Receptor tyrosine kinase-like orphan receptor 1 (ROR1) by using strictinin, a small molecule ROR1 inhibitor.

Methods

The methods performed in this study include western blots, methyl thiazolyl tetrazolium (MTT) proliferation assays, phosphatidylserine apoptosis assays, apoptosis flow cytometry (Annexin V, caspase 3/7), migration scratch assays, Boyden chamber invasion assays, and cell cycle flow cytometry.

Results

Strictinin was most lethal against PC3 [half-maximal drug inhibitory concentration (IC50) of 277.2 µmol/L], an ARneg-AI cell type that expresses the highest levels of ROR1. Strictinin inhibited ROR1 expression, downstream phosphatidylinositol 3-kinase (PI3K)-protein kinase B (AKT)-glycogen synthase kinase 3beta (GSK3β) pro-survival signaling, and epithelial-to-mesenchymal transition markers in PC3 cells. Additionally, strictinin decreased PC3 cell migration and invasion, while increasing S-phase cell cycle arrest. In ARneg-AI DU145 cells, strictinin inhibited ROR1 expression and modulated downstream AKT-GSK3β signaling. Furthermore, strictinin exhibited anti-migratory, anti-invasive, but minimal pro-apoptotic effects in DU145 cells likely due to DU145 having less ROR1 expression in comparison to PC3 cells. Throughout the study, strictinin minimally impacted the phenotype of normal prostatic epithelial cells RWPE-1 (IC50 of 658.5 µmol/L). Strictinin was further identified as synergistic with docetaxel [combination index (CI) = 0.311] and the combination therapy was found to reduce the IC50 of strictinin to 38.71 µmol/L in PC3 cells.

Conclusions

ROR1 is an emerging molecular target that can be utilized for treating prostate cancer. The data from this study establishes strictinin as a potential therapeutic agent that targets ARneg-AI prostate cancer with elevated ROR1 expression to reduce the migration, invasion, cell cycle progression, and survival of prostate cancer.

Discovery of dolutegravir-1,2,3-triazole derivatives against prostate cancer via inducing DNA damage

Prostate cancer (PCa) is the second most frequently diagnosed cancer among men, causing a huge number of deaths each year. Traditional chemotherapy for PCa mostly focused on targeting androgen receptors. However, some of the patients would develop resistance to hormonal therapy. In these cases, it is suggested for these patients to administer treatments in combination with other chemotherapeutics. Current chemotherapeutics for metastatic castration-resistant PCa could hardly reach satisfying effects, therefore it is crucial to explore novel agents with low cytotoxicity. Herein, a common drug against the human immunodeficiency virus (HIV), the dolutegravir (DTG) was modified to become a series of dolutegravir-1,2,3-triazole derivatives. Among these compounds, the 4d and 4q derivatives were verified with high anti-tumor efficiency, suppressing the proliferation of the prostate cancer cells PC3 and DU145. These compounds function by binding to the poly (adenosine diphosphate-ribose) polymerase (PARP), inactivating the PARP and inducing DNA damage in cancer cells. It is noteworthy that the 4d and 4q derivatives showed almost no impact on normal cells and mice. Thereby, the results reveal that these dolutegravir-1,2,3-triazole compounds are potential chemotherapeutics for PCa treatment.

Prostate cancer patient stratification by molecular signatures in the Veterans Precision Oncology Data Commons

Veterans are at an increased risk for prostate cancer, a disease with extraordinary clinical and molecular heterogeneity, compared with the general population. However, little is known about the underlying molecular heterogeneity within the veteran population and its impact on patient management and treatment. Using clinical and targeted tumor sequencing data from the National Veterans Affairs health system, we conducted a retrospective cohort study on 45 patients with advanced prostate cancer in the Veterans Precision Oncology Data Commons (VPODC), most of whom were metastatic castration-resistant. We characterized the mutational burden in this cohort and conducted unsupervised clustering analysis to stratify patients by molecular alterations. Veterans with prostate cancer exhibited a mutational landscape broadly similar to prior studies, including KMT2A and NOTCH1 mutations associated with neuroendocrine prostate cancer phenotype, previously reported to be enriched in veterans. We also identified several potential novel mutations in PTEN, MSH6, VHL, SMO, and ABL1 Hierarchical clustering analysis revealed two subgroups containing therapeutically targetable molecular features with novel mutational signatures distinct from those reported in the Catalogue of Somatic Mutations in Cancer database. The clustering approach presented in this study can potentially be used to clinically stratify patients based on their distinct mutational profiles and identify actionable somatic mutations for precision oncology.

Addition of Olaparib to the New Hormonal Agent Regimen for Metastatic Castration-Resistant Prostate Cancer: A Systematic Review and Meta-Analysis

Background

The emergence of olaparib, a poly (adenosine diphosphate (ADP)-ribose) polymerase (PARP) inhibitor to treat metastatic castration-resistant prostate cancer (mCRPC), created a measurable clinical question on whether the agent positively influences the treatment outcomes and acceptable safety factors. The objective was to elaborate on the efficacy and safety of olaparib-added regimens in treating mCRPC patients as compared to the established guideline.

Methods

The literature search was performed on several scientific databases, e.g., PubMed, Cochrane, and ScienceDirect, by applying the Boolean Term method. Statistical and risk of bias (RoB) analyses were calculated through RevMan 5.4.1. to investigate our outcomes, i.e., progression-free survival (PFS) and overall survival (OS) with the reported adverse effects (AEs). These outcomes were presented in hazard ratio (HR) and risk ratio (RR).

Results

Three trials consisting of 1,325 individuals with comparable baseline characteristics were investigated. The meta-analysis showed that introducing olaparib into the regimens significantly improved the PFS (HR 0.59 (0.48 - 0.73); P < 0.05), which disclosed even better outcomes among mutated homologous recombinant repair (HRR) and ataxia-telangiectasia mutated (ATM) gene (HR 0.43 (0.30 - 0.62); P < 0.05) in 95% confidence interval (CI). Furthermore, similar outcomes were observed in OS analysis (HR 0.81 (0.67 - 0.99); P < 0.05), despite olaparib group disclosed higher AEs rate with insignificant difference in mortality rate.

Conclusion

The efficacy and safety of olaparib-added regimens in mCRPC patients need to be explored more extensively in trials because they are beneficial, particularly among HRR-mutated individuals.

Gene Expression and DNA Methylation as Prognostic Markers in Metastatic Castration-Resistant Prostate Cancer: Analysis of Circulating Tumor Cells and Paired Plasma-Derived Exosomes

Prostate cancer (PCa) is the most prevalent cancer among men and is the second leading cause of cancer-related death in the United States [...].

OCT4‑positive circulating tumor cells may predict a poor prognosis in patients with metastatic castration‑resistant prostate cancer treated with abiraterone plus prednisone therapy

Octamer-binding transcription factor 4 (OCT4) and circulating tumor cells (CTCs) are key factors associated with tumor metastasis and drug resistance in cancer. The present prospective study aimed to investigate the prevalence of OCT4-positive (OCT4+) CTCs and the potential association with the clinical features and survival of patients with metastatic castration-resistant prostate cancer (mCRPC) treated with abiraterone + prednisone. In total, 70 patients with mCRPC treated with abiraterone + prednisone were enrolled in the present study and peripheral blood samples were collected prior to treatment initiation to determine CTC count via a Canpatrol system. RNA in situ hybridization was performed for OCT4+ CTC quantification. Lactate dehydrogenase (LDH) was detected by automatic biochemical analyzer (AU54000, OLYMPUS). Results demonstrated that 34 (48.6%), 21 (30.0%) and 15 (21.4%) patients harbored OCT4+ (CTC+/OCT4+) or OCT4-negative CTCs (CTC+/OCT4-) or were CTC-negative (CTC-), respectively. Notably, CTC+/OCT4+ occurrence was associated with visceral metastasis and high levels of LDH. In addition, radiographic progression-free survival [rPFS; median, 15.0, 95% confidence interval (CI), 9.6-20.4 vs. not reached vs. median, 29.5, 95% CI, 18.6-40.4 months; P=0.001] and overall survival (OS) were significantly decreased (median, 27.3, 95% CI, 20.1-34.5 vs. not reached vs. not reached; P=0.016) in CTC+/OCT4+ compared with CTC+/OCT4- and CTC- patients. Subsequently, the adjustment was performed by multivariate Cox regression models, which revealed that CTC+/OCT4+ (vs. CTC+/OCT4- or CTC-) was independently associated with decreased rPFS [hazard ratio (HR), 3.833; P<0.001] and OS (HR, 3.938; P=0.008). In conclusion, OCT4+ CTCs were highly prevalent in patients with mCRPC and associated with visceral metastasis and increased levels of LDH. Thus, the presence of OCT4+ CTCs may serve as an independent prognostic factor for patients with mCRPC treated with abiraterone + prednisone.

Treatment landscape and burden of disease in metastatic castration-resistant prostate cancer: systematic and structured literature reviews

Purpose

Metastatic castration-resistant prostate cancer (mCRPC) is a lethal disease that imposes a major burden on patients and healthcare systems. Three structured literature reviews (treatment guidelines, treatment landscape, and human/clinical/patient burden) and one systematic literature review (economic burden) were conducted to better understand the disease burden and unmet needs for patients with late-stage mCRPC, for whom optimal treatment options are unclear.

Methods

Embase®, MEDLINE®, MEDLINE® In-Process, the CENTRAL database (structured and systematic reviews), and the Centre for Reviews and Dissemination database (systematic review only) were searched for English-language records from 2009 to 2021 to identify mCRPC treatment guidelines and studies related to the treatment landscape and the humanistic/economic burden of mCRPC in adult men (aged ≥18 years) of any ethnicity.

Results

In total, six records were included for the treatment patterns review, 14 records for humanistic burden, nine records for economic burden, three records (two studies) for efficacy, and eight records for safety. Real-world treatment patterns were broadly aligned with treatment guidelines and provided no optimal treatment sequencing beyond second line other than palliative care. Current post-docetaxel treatments in mCRPC are associated with adverse events that cause relatively high rates of treatment discontinuation or disruption. The humanistic and economic burdens associated with mCRPC are high.

Conclusion

The findings highlight a lack of treatment options with novel mechanisms of action and more tolerable safety profiles that satisfy a risk-to-benefit ratio aligned with patient needs and preferences for patients with late-stage mCRPC. Treatment approaches that improve survival and health-related quality of life are needed, ideally while simultaneously reducing costs and healthcare resource utilization.

Niraparib plus abiraterone acetate with prednisone in patients with metastatic castration-resistant prostate cancer and homologous recombination repair gene alterations: second interim analysis of the randomized phase III MAGNITUDE trial

BACKGROUND

Patients with metastatic castration-resistant prostate cancer (mCRPC) and BRCA alterations have poor outcomes. MAGNITUDE found patients with homologous recombination repair gene alterations (HRR+), particularly BRCA1/2, benefit from first-line therapy with niraparib plus abiraterone acetate and prednisone (AAP). Here we report longer follow-up from the second prespecified interim analysis (IA2).

PATIENTS AND METHODS

Patients with mCRPC were prospectively identified as HRR+ with/without BRCA1/2 alterations and randomized 1 : 1 to niraparib (200 mg orally) plus AAP (1000 mg/10 mg orally) or placebo plus AAP. At IA2, secondary endpoints [time to symptomatic progression, time to initiation of cytotoxic chemotherapy, overall survival (OS)] were assessed.

RESULTS

Overall, 212 HRR+ patients received niraparib plus AAP (BRCA1/2 subgroup, n = 113). At IA2 with 24.8 months of median follow-up in the BRCA1/2 subgroup, niraparib plus AAP significantly prolonged radiographic progression-free survival {rPFS; blinded independent central review; median rPFS 19.5 versus 10.9 months; hazard ratio (HR) = 0.55 [95% confidence interval (CI) 0.39-0.78]; nominal P = 0.0007} consistent with the first prespecified interim analysis. rPFS was also prolonged in the total HRR+ population [HR = 0.76 (95% CI 0.60-0.97); nominal P = 0.0280; median follow-up 26.8 months]. Improvements in time to symptomatic progression and time to initiation of cytotoxic chemotherapy were observed with niraparib plus AAP. In the BRCA1/2 subgroup, the analysis of OS with niraparib plus AAP demonstrated an HR of 0.88 (95% CI 0.58-1.34; nominal P = 0.5505); the prespecified inverse probability censoring weighting analysis of OS, accounting for imbalances in subsequent use of poly adenosine diphosphate-ribose polymerase inhibitors and other life-prolonging therapies, demonstrated an HR of 0.54 (95% CI 0.33-0.90; nominal P = 0.0181). No new safety signals were observed.

CONCLUSIONS

MAGNITUDE, enrolling the largest BRCA1/2 cohort in first-line mCRPC to date, demonstrated improved rPFS and other clinically relevant outcomes with niraparib plus AAP in patients with BRCA1/2-altered mCRPC, emphasizing the importance of identifying this molecular subset of patients.

Frailty and survival among veterans treated with abiraterone or enzalutamide for metastatic castration-resistant prostate cancer

INTRODUCTION

Abiraterone and enzalutamide are treatments for metastatic castration-resistant prostate cancer (mCRPC). Due to a lack of head-to-head trials, they are prescribed interchangeably. However, the drugs have different pharmacokinetics and thus may have differing efficacy and adverse effects influenced by patient functional status and comorbid diseases. Additionally, mCRPC mainly affects older adults and since the prevalence of frailty increases with age, frailty is an important patient factor to consider in personalizing drug selection.

MATERIALS AND METHODS

We conducted a retrospective observational study of US veterans treated with abiraterone or enzalutamide for mCRPC from September 2014 to June 2017. Frailty was assessed using the Veterans Affairs Frailty Index (VA-FI), which utilizes administrative codes to assign a standardized frailty score. Patients were categorized as frail if VA-FI scores were > 0.2. The primary outcome was difference in overall survival (OS) between the two treatment groups. Cox regression modeling and propensity score matching was used to compare between abiraterone and enzalutamide treatments.

RESULTS

We identified 5,822 veterans, 57% of whom were initially treated with abiraterone and 43% with enzalutamide. Frail patients (n = 2,314; 39.7%) were older, with a mean age of 76.1 versus 74.9 years in the non-frail group (n = 3,508; 60.3%, p < 0.001) and had shorter OS compared to non-frail patients regardless of treatment group (18.5 vs. 26.6 months, p < 0.001). Among non-frail patients there was no significant difference in OS between abiraterone and enzalutamide treatment (27.7 vs 26.1 months, p = 0.07). However, frail patients treated with enzalutamide versus abiraterone had improved OS (20.7 vs 17.2 months, p < 0.001). In a propensity score matched analysis of frail patients (n = 2,070), enzalutamide was associated with greater median OS (24.1 vs 20.9 months, p < 0.001). In patients with dementia, enzalutamide was associated with longer OS (19.4 vs. 16.6 months, p = 0.003).

DISCUSSION

In this study of 5822 US veterans with mCRPC, treatment with enzalutamide was associated with improved OS compared to abiraterone among frail veterans and veterans with dementia, but not among non-frail veterans. Future studies should evaluate interactions between frailty and cancer treatments to optimize selection of therapy among frail adults.

Engineered anti-prostate cancer CAR-neutrophils from human pluripotent stem cells

Immunotherapy is a powerful technique where immune cells are modified to improve cytotoxicity against cancerous cells to treat cancers that do not respond to surgery, chemotherapy, or radiotherapy. Expressing chimeric antigen receptor (CAR) in immune cells, typically T lymphocytes, is a practical modification that drives an immune response against cancerous tissue. CAR-T efficacy is suboptimal in solid tumors due to the tumor microenvironment (TME) that limits T lymphocyte cytotoxicity. In this study, we demonstrate that neutrophils differentiated from human pluripotent stem cells modified with AAVS1-inserted CAR constructs showed a robust cytotoxic effect against prostate-specific membrane antigen (PSMA) expressing LNCaP cells as a model for prostate cancer in vitro. Our results suggest that engineered CAR can significantly enhance the neutrophil anti-tumor effect, providing a new avenue in treating prostate cancers.

Elevated labile iron in castration-resistant prostate cancer is targetable with ferrous iron-activatable antiandrogen therapy

Clinical responses to second generation androgen signaling inhibitors (e.g., enzalutamide) in metastatic castration-resistant prostate cancer (mCRPC) are variable and transient, and are associated with dose limiting toxicities, including rare but severe CNS effects. We hypothesized that changes to iron metabolism coincident with more advanced disease might be leveraged for tumor-selective delivery of antiandrogen therapy. Using the recently described chemical probes SiRhoNox and 18F-TRX in mCRPC models, we found elevated Fe2+ to be a common feature of mCRPC in vitro and in vivo. We next synthesized ferrous-iron activatable drug conjugates of second and third-generation antiandrogens and found these conjugates possessed comparable or enhanced antiproliferative activity across mCRPC cell line models. Mouse pharmacokinetic studies showed that these prototype antiandrogen conjugates are stable in vivo and limited exposure to conjugate or free antiandrogen in the brain. Our results reveal elevated Fe2+ to be a feature of mCRPC that might be leveraged to improve the tolerability and efficacy of antiandrogen therapy.

Calcium phosphate-based nanomedicine mediated CRISPR/Cas9 delivery for prostate cancer therapy

Introduction: Erythropoietin producing hepatocyte receptor A2 (EphA2) is widely presented in the tumor cells, closely related to tumor cell migration, not cell apoptosis and proliferation. Based on its high expression in castration-resistant prostate cancer (CRPC), we herein develop a CRISPR-Cas9-based genome-editing nanomedicine to target erythropoietin producing hepatocyte receptor A2 for the treatment of castration-resistant prostate cancer. Methods: To this end, TAT was designed to stabilize the distribution of calcium, and then bound to ribonucleoprotein (RNP) to form nanoparticles RNP@CaP-TAT. Results: This nanoparticle has a simple synthesis process with good biocompatible, to achieve the knockout of tumor cells (PC-3) targeting erythropoietin producing hepatocyte receptor A2 gene and to effectively suppress the migration of tumor cells. Discussion: This delivery genome editing system provides a promising gene therapy strategy for the treatment of castration-resistant prostate cancer, showing good potential against castration-resistant prostate cancer tumor metastasis. In addition, it can be extended to other types of cancer with highly heterogeneous gene expression.

Targeting mTOR Complex 2 in Castration-Resistant Prostate Cancer with Acquired Docetaxel Resistance

PURPOSE

Mammalian Target of rapamycin (mTOR) plays a central role in regulating cell growth, proliferation, and cell cycle. The key component of mTORC2 is highly expressed in docetaxel-resistant prostate cells. However, the underlying molecular effects on prostate cells remain unclear.

METHODS

A docetaxel-resistant human prostate cell line (PC-3/DTX) was constructed to investigate the role of mTORC2 in docetaxel resistance. The lentivirus was transfected into cells to knock down the expression of Rictor, and cell viability was measured by Cell Counting Kit 8 (CCK-8). Flow cytometry was used to analyze the cell cycle, and the changes in related signal cascades were assessed by immunohistochemistry (IHC) staining and Western blot.

RESULTS

Docetaxel showed the lowest IC50 (50% inhibitory concentration) in PC-3/DTX cells with sh-RNA. Decreased Rictor expression resulted in a larger proportion of arrested cells in the G0/G1 phase in PC-3/DTX cells. The IC50 values of the AZD8055 group were lower than in the Rapamycin group when treated with docetaxel again. Furthermore, a larger proportion of PC-3/DTX cells were arrested in the G0/G1 phase in the AZD8055 group compared to the Rapamycin group. The IHC results of the prostate cancer tissues from a CRPC patient revealed the over expression of Rictor only, while Raptor expression was unaffected.

CONCLUSION

We investigated the role of mTORC2 signaling on the acquired docetaxel -resistant PC-3 cells to identify potential methods for clinical treatment. MTORC2 expression is essential for docetaxel drug resistance of PC-3 cells. The mTORC1/2 inhibitor AZD8055 caused more significant disruption of mTORC2 kinase activity than the mTORC1 inhibitor Rapamycin, which lead to decreased docetaxel-mediated resistance. Therefore, reversing docetaxel resistance, may become a therapeutic option in the treatment of mCRPC patients.

Oncolyic Virotherapy for Prostate Cancer: Lighting a Fire in Winter

As the most common cancer of the genitourinary system, prostate cancer (PCa) is a global men's health problem whose treatments are an urgent research issue. Treatment options for PCa include active surveillance (AS), surgery, endocrine therapy, chemotherapy, radiation therapy, immunotherapy, etc. However, as the cancer progresses, the effectiveness of treatment options gradually decreases, especially in metastatic castration-resistant prostate cancer (mCRPC), for which there are fewer therapeutic options and which have a shorter survival period and worse prognosis. For this reason, oncolytic viral therapy (PV), with its exceptional properties of selective tumor killing, relatively good safety in humans, and potential for transgenic delivery, has attracted increasing attention as a new form of anti-tumor strategy for PCa. There is growing evidence that OV not only kills tumor cells directly by lysis but can also activate anticancer immunity by acting on the tumor microenvironment (TME), thereby preventing tumor growth. In fact, evidence of the efficacy of this strategy has been observed since the late 19th century. However, subsequently, interest waned. The renewed interest in this therapy was due to advances in biotechnological methods and innovations at the end of the 20th century, which was also the beginning of PCa therapy with OV. Moreover, in combination with chemotherapy, radiotherapy, gene therapy or immunotherapy, OV viruses can have a wide range of applications and can provide an effective therapeutic result in the treatment of PCa.

Overcoming Obstacles in Liquid Biopsy Developments for Prostate Cancer

Prostate cancer is one of the most common malignancies in men. Over time, it can metastasize and become lethal once it exhausts hormonal therapies and transitions into castration-resistant prostate cancer (CRPC). Several therapies have been recently approved for advanced prostate cancer, but identifying biomarkers for current treatments and searching for more effective treatments are urgently needed. Liquid biopsy is a powerful tool for isolating genetic material, proteins, and whole tumor cells from the blood. In recent decades, this technology has rapidly advanced, allowing for better insights into the pathogenesis and treatment response in different stages of prostate cancer. In this review, we summarize important clinical studies involving liquid biopsies in prostate cancer with a focus on advanced disease, notably regarding circulating tumor DNA, circulating tumor cells, and exosomes. We highlight the progress and the challenges that still exist for these technologies. Finally, we discuss promising avenues that will further expand the importance of liquid biopsy in the care for prostate cancer patients.

PARP Inhibitors: A New Horizon for Patients with Prostate Cancer

The introduction of PARP inhibitors (PARPi) in prostate cancer is a milestone and provides a pathway to hope in fighting this disease. It is the first time that drugs, based on the concept of synthetic lethality, have been approved for prostate cancer. In addition, it is also the first time that genetic mutation tests have been included in the therapeutic algorithm of this disease, representing a significant step forward for precision and personalized treatment of prostate cancer. The objectives of this review are: (1) understanding the mechanism of action of PARPi in monotherapy and combinations; (2) gaining insights on patient selection for PARPi; (3) exposing the pivotal studies that have allowed its approval, and; (4) offering an overview of the ongoing trials. Nevertheless, many unsolved questions remain, such as the number of patients who could potentially benefit from PARPi, whether to use PARPi in monotherapy or in combination, and when is the best time to use them in advanced or localized disease. To answer these and other questions, many clinical trials are underway. Some of them have recently demonstrated promising results that may favor the introduction of new combinations in metastatic castration-resistant prostate cancer.

Prospective assessment of AR splice variant and multi-biomarker expression on circulating tumor cells of mCRPC patients undergoing androgen receptor targeted agents: interim analysis of PRIMERA trial (NCT04188275)

Circulating tumor cells detection and ARV7 expression are associated with worse clinical outcomes in metastatic Castration-Resistant Prostate Cancer (mCRPC) undergoing Androgen Receptor Targeted Agents. ARFL, PSMA and PSA may help to refine prognostic models. In our institution, a prospective observational trial testing CTC detection in mCPRC undergoing I line ARTA therapy terminated the planned enrollment in 2020. Here, we present a pre-planned interim analysis with 18 months of median follow-up. RT-qPCR was used to determine the CTC expression of PSA, PSMA, AR and ARV7 before starting ARTA. PSA-drop, Progression-Free and Overall Survival (PFS and OS) and their correlation with CTC detection were reported. Forty-four patients were included. CTC were detected in 43.2% of patients, of whom 8.94% expressed PSA, 15.78% showed ARV7, 63.15% and 73.68% displayed ARFL and PSMA, respectively. Biochemical response was significantly improved in CTC + vs CTC- patients, with median PSA-drop of 18.5 vs 2.5 ng/ml (p = 0.03). After a median follow-up of 18 months, 50% of patients progressed. PFS was significantly longer in CTC- patients (NR vs 16 months). Eight (18.2%) patients died, a non-significant trend in terms of OS was detected in favor of CTC- patients (NR vs 29 months, p = 0.05). AR, PSA and PSMA expression in CTC + had no significant impact on PSA-drop, PFS or OS. PRIMERA-trial confirmed the CTC detection predictive importance in mCRPC patients.

Identification of a Gene Signature to Aid Treatment Decisions by Integrated Analysis of Mutated Genes Between Primary and Metastatic Prostate Cancer

Prostate cancer is one of the most common malignancies in males. Despite the recent development of advanced diagnostic platforms and treatment, patients with metastatic disease still have a poor five-year survival rate. Cancer metastasis is correlated with the characteristics of the tumor microenvironment and is significantly associated with patient prognosis. In this study, we obtained mutated genes with significant differences between primary and metastatic prostate cancer from the COSMIC database. Unsupervised consensus clustering was used based on the 1,051 genes obtained, and two PCa clusters were identified, which exhibited different prognostic outcomes and immune characteristics. Next, we generated a scoring system and evaluated the prognostic value of riskscore and its potential to aid treatment decisions in clinical practice. The riskscore could be applied to predict patients’ response to immunotherapy and sensitivity to Docetaxel. In conclusion, this study performed an integrated analysis of mutated genes between primary and metastatic prostate cancer and provides a novel assessment scheme to precisely select treatment strategies.

Advances in the role of heat shock protein 90 in prostate cancer

Prostate cancer is one of the most common tumours in adult men and heat shock proteins play an important biological function in prostate cancer as molecular chaperones involved in the pathogenesis, diagnosis, treatment and prognosis of a wide range of tumours. Among them, increased expression of HSP90, a member of the heat shock protein family, is associated with resistance to prostate cancer denervation and can promote tumour resistance, invasion and bone metastasis, thus making prostate cancer more difficult to treat. Therefore, targeting HSP90 in prostate cancer could be a promising strategy for oncology treatment. This paper reviews the structure and function of HSP90, HSP90-mediated denudation resistance in prostate cancer and HSP90-targeted antitumor therapy, with the aim of providing a new theoretical basis for prostate cancer treatment options in the clinical setting.