DNA-Repair Defects and Olaparib in Metastatic Prostate Cancer

Empowering PARP inhibition through rational combination: Mechanisms of PARP inhibitors and combinations with a focus on the treatment of metastatic castration-resistant prostate cancer

Poly (ADP-ribose) polymerase (PARP) inhibitors have revolutionized the treatment of many cancers. Metastatic castration-resistant prostate cancer (mCRPC) is an area where PARP inhibitors are intensively studied; the efficacy with PARP inhibitor monotherapy in patients with homologous recombination repair mutations following novel hormonal therapy have prompted the investigation of combination therapy, with adding an androgen receptor pathway inhibitor (ARPI) being one focus of research. Data on PARP inhibitor monotherapy and combination therapy for mCRPC are accumulating, and it is important to navigate through the complex data to inform treatment decision. Here we review the mechanisms of action of PARP inhibitors, their pharmacological properties, the synergistic activity of PARP inhibitors plus other drug classes, and the clinical evidence on monotherapy and combination therapy in patients with mCRPC. We propose key considerations in the selection of agents and treatment sequence for mCRPC, such as efficacy, toxicity profiles, biomarkers, and interactions with concomitant medications.

Expert Opinion on Current Treatment Alternatives for Patients With Prostate Cancer Progressing From the Metastatic Hormone-Sensitive Stage to the Castration-Resistant Stage After Receiving Early Treatment Intensification

For patients with castration-sensitive prostate cancer (mCSPC), treatment intensification with androgen deprivation therapy (ADT) plus new androgen receptor pathway inhibitors (ARPIs) has opened a scenario where no guidance exists to indicate the best treatment after progression to metastatic castration-resistant prostate cancer (mCRPC). Clinical decision-making has become even more complex, with the proven benefit for selected patients of triplet therapy with abiraterone or darolutamide added to the double combination therapy of ADT plus docetaxel. The profile of patients for whom triple therapy would be more beneficial is being defined beyond metastatic disease presentation and volume (eg, poor prognosis features). In October 2023 and October 2024, a panel of eight Spanish medical oncologists with expertise in the management of prostate cancer met to discuss the challenges in treating mCRPC. The scientific evidence was reviewed during this meeting, knowledge and experience were shared, and controversies were discussed until a consensus was reached. This information was collected and turned into a manuscript aimed at helping clinicians determine the optimal treatment sequence after disease progression based on scientific evidence and experts' opinions and consensus. To this end, the profile of mCSPC patients who may have received double or triplet therapy is analyzed, current treatment options are reviewed, and treatment algorithms are proposed. New and expected advancements in this field are also presented.

Urolithins: Emerging natural compound targeting castration-resistant prostate cancer (CRPC)

Castration-resistant prostate cancer (CRPC) presents a significant challenge due to its resistance to conventional androgen deprivation therapies. Urolithins, bioactive metabolites derived from ellagitannins, have recently emerged as promising therapeutic agents for CRPC. Urolithins not only inhibit androgen receptor (AR) signaling, a crucial factor in the progression of CRPC, but also play a key role in regulating oxidative stress by their antioxidant properties, thereby inhibiting increased reactive oxygen species, a common feature of the aggressive nature of CRPC. Research has shown that urolithins induce apoptosis and diminish pro-survival signaling, leading to tumor inhibition. This review delves into the intricate mechanisms through which urolithins exert their therapeutic effects, focusing on both AR-dependent and AR-independent pathways. It also explores the exciting potential of combining urolithins with androgen ablation therapy, opening new avenues for CRPC treatment.

A qualitative study of the experiences of patients with prostate cancer when receiving negative genetic results: "I still don't have a grasp of what it all means"

Germline genetic testing has been increasingly conducted for treatment implications in patients with prostate cancer due to the expansion of testing eligibility. Understanding patients' comprehension of genetic results is crucial for establishing effective result disclosure practices. This importance has grown due to the increasing prevalence of negative genetic results being conveyed via electronic communication and by providers without a genetics specialization. This study explores patients with prostate cancer's perceptions of genetic results communication. We analyzed 24 qualitative, semi-structured interviews with patients with prostate cancer at an urban safety-net hospital who had genetic results documented in their medical records. Interview questions focused on patient experiences with genetic referrals, genetic counseling, and genetic result disclosure. Audio recordings were professionally transcribed and analyzed by the study team utilizing an inductive thematic approach to generate themes from recurring codes. Of those who participated, 18 were interviewed in English, 5 in Spanish, and 1 in Haitian Creole. No participants reported having a pathogenic variant identified with genetic testing. Study participants identified a number of gaps in results communication which led to misconceptions regarding hereditary cancer risk. Three themes were generated: (1) Patients desired clear communication about the next steps after genetic testing, (2) Patients commonly experienced cognitive dissonance with negative genetic results given personal and family history of cancer, and (3) Patients felt reassurance from negative genetic results. This research suggests that maintaining conversations between patients and healthcare providers alongside the delivery of negative results assists in patient comprehension. Additionally, it is essential to evaluate the accessibility and appropriateness of notes and results sent to patients. Ultimately, understanding communication barriers in genetic results return is imperative in order to provide high-quality genetic care.

Synergistic targeting strategies for prostate cancer

Prostate cancer is the second most commonly diagnosed cancer and the fifth leading cause of death among men worldwide. Androgen deprivation therapy is a common prostate cancer treatment, but its efficacy is often hindered by the development of resistance, which results in reducing survival benefits. Immunotherapy showed great promise in treating solid tumours; however, clinically significant improvements have not been demonstrated for patients with prostate cancer, highlighting specific drawbacks of this therapeutic modality. Hence, exploring novel strategies to synergistically enhance the efficacy of prostate cancer immunotherapy is imperative. Clinical investigations have focused on the combined use of targeted or gene therapy and immunotherapy for prostate cancer. Notably, tumour-specific antigens and inflammatory mediators are released from tumour cells after targeted or gene therapy, and the recruitment and infiltration of immune cells, including CD8+ T cells and natural killer cells activated by immunotherapy, are further augmented, markedly improving the efficacy and prognosis of prostate cancer. Thus, immunotherapy, targeted therapy and gene therapy could have reciprocal synergistic effects in prostate cancer in combination, resulting in a proposed synergistic model encompassing these three therapeutic modalities, presenting novel potential treatment strategies for prostate cancer.

Exploring the Potential of Homologous Recombination Protein PALB2 in Synthetic Lethal Combinations

Cells with defective homologous recombination (HR) are highly sensitive to poly(ADP-ribose) polymerase (PARP) inhibition. Current therapeutic approaches leverage this vulnerability by using PARP inhibitors in cells with genetically compromised HR. However, if HR factors in cancer cells could be inhibited or degraded pharmacologically, it might reveal other opportunities for synergistic combinations. In this study, we developed a model system that recapitulates PARP/HR synthetic lethality by integrating a small-molecule responsive zinc-finger degron into the HR factor Partner and Localizer of BRCA2 (PALB2). We further tested a series of peptide ligands for PALB2 based on its natural binding partners, which led to the discovery of a high affinity peptide that will support future work on PALB2 and HR. Together, our findings validate PALB2 as a promising drug target and provide the tools and starting points for developing molecules with therapeutic applications.

Whole-exome sequencing provides assessment of homologous recombination deficiency for identification of PARPi-responsive ovarian tumors

BACKGROUND/OBJECTIVES

Homologous recombination repair deficiency (HRD) is frequently detected in gynecological cancers and is associated with sensitivity to poly-ADP ribose polymerase inhibition (PARPi). BRCA1/2 mutations have been approved as biomarkers for PARPi therapy, along with genomic patterns such as genomic loss of heterozygosity (gLOH) and large-scale transitions (LSTs). Clinical applications of various HRD assays are still under investigation. Here we validate the performance of a novel HRD assay based on whole-exome sequencing (WES).

METHODS

WES was used to evaluate gLOH, LST, and BRCA mutations and this data was compared to standard assays. An optimized genomic scar score (GSS) was based on combined gLOH and LST. A comprehensive HRD score was then developed, combining GSS and BRCA status. Survival data from 1661 PARPi-treated ovarian cancer patients was queried to optimize GSS and HRD scores associated with PARPi response.

RESULTS

A comparison of WES results to the OncoScan CNV assay and Myriad MyChoice assay showed high concordance for LOH values and GSS values, respectively. Median overall survival in PARPi-treated patients was 50.8 months for GSS-high, BRCA1/2-mut, 42.7 months for GSS-high, BRCA1/2-WT, and 36.6 months for GSS-low, BRCA1/2-WT patients with significant differences between each group. Combining the BRCA1/2-mut and WT GSS-high groups resulted in a median OS value of 47.8 months, significantly higher than the GSS-low BRCA1/2-WT group.

CONCLUSIONS

The use of a WES assay to assess BRCA results, along with a GSS method incorporating gLOH and LST, produced a HRD test that is predictive for PARPi therapy.

Niraparib and Abiraterone Acetate plus Prednisone in Metastatic Castration-resistant Prostate Cancer: Final Overall Survival Analysis for the Phase 3 MAGNITUDE Trial

BACKGROUND AND OBJECTIVE

The phase 3 MAGNITUDE trial previously met its primary endpoint of an improvement in radiographic progression-free survival with niraparib + abiraterone acetate and prednisone (AAP) versus placebo + AAP in patients with metastatic castration-resistant prostate cancer (mCRPC) and alterations in genes involved in DNA homologous recombination repair (HRR+), particularly in BRCA1/2.

METHODS

Patients were prospectively screened for HRR alterations and randomized 1:1 to niraparib + AAP (n = 212) or placebo + AAP (n = 211). We report results from the prespecified, event-driven, final analysis of secondary efficacy endpoints.

KEY FINDINGS AND LIMITATIONS

Final analysis at median follow-up of 37.3 mo revealed no difference in overall survival (OS) between niraparib + AAP and placebo + AAP in the HRR+ population (hazard ratio [HR] 0.931, 95% confidence interval [CI] 0.720-1.203; p = 0.585) or the subgroup with BRCA1/2 alterations (HR 0.788, 95% CI 0.554-1.120; nominal p = 0.183). Prespecified multivariate analyses adjusted for baseline prognostic factors showed a trend toward longer OS with niraparib + AAP over placebo + AAP in the HRR+ population (HR 0.785, 95% CI 0.606-1.016; nominal p = 0.066) and the BRCA1/2 subgroup (HR 0.663, 95% CI 0.464-0.947; nominal p = 0.024). Niraparib + AAP led to a statistically significant, clinically meaningful improvement in time to symptomatic progression in both the HRR+ population (HR 0.547, 95% CI 0.396-0.754; p = 0.006) and the BRCA1/2 subgroup (HR 0.562, 95% CI 0.371-0.849; nominal p = 0.006), and a clinically meaningful improvement in time to cytotoxic chemotherapy in the HRR+ population (HR 0.688, 95% CI 0.499-0.950; p = 0.022) and the BRCA1/2 subgroup (HR 0.598, 95% CI 0.387-0.924; nominal p = 0.019) in comparison to placebo + AAP. The niraparib + AAP safety profile remains unchanged at longer follow-up; adverse events were primarily hematologic and manageable.

CONCLUSIONS AND CLINICAL IMPLICATIONS

The MAGNITUDE final analysis showed that patients with HRR+ mCRPC, including those with the approved indication of BRCA-altered mCRPC, generally continue to benefit from first-line treatment with niraparib + AAP in comparison to placebo + AAP.

FOXA1-dependent NSUN2 facilitates the advancement of prostate cancer by preserving TRIM28 mRNA stability in a m5C-dependent manner

RNA epigenetics is gaining increased attention for its role in the initiation, metastasis, and drug resistance of tumors. These studies have primarily focused on m6A modification. However, despite being the second most abundant modification found in RNA, the role of m5C modification in prostate cancer remains largely unexplored. Here, we predict an RNA m5C methyltransferase, NSUN2, as a potential therapeutic target for prostate cancer using various bioinformatics approaches, and verify the potential of NSUN2 as a target through multiple preclinical models. Mechanistically, NSUN2 enhances the stability of TRIM28 mRNA by adding m5C modification, promoting the expression of TRIM28. Concurrently, FOXA1, a prostate cancer lineage-specific transcription factor, transcriptionally activates the expression of NSUN2. Our study confirms the clinical potential of targeting RNA epigenetics for the treatment of prostate cancer and elucidates, mechanistically, how RNA epigenetics participates in the complex biological activities within tumors via the FOXA1-NSUN2-TRIM28 axis.

The deubiquitination-PARylation positive feedback loop of the USP10-PARP1 axis promotes DNA damage repair and affects therapeutic efficacy of PARP1 inhibitor

PARP1 initiates DNA repair pathways including single-strand break repair (SSBR) by recruiting multiple DNA repair factors via poly ADP-ribosylation (PARylation) of target proteins. However, how PARP1 is stabilized and activated to promote DNA damage repair remains unclear. Here we report that DNA damage generates a ROS signal, which triggers USP10 to interact with and stabilize PARP1 by deubiquitinating the K418 site in an ATM-dependent manner. In turn, PARP1 mediates PARylation of USP10 at amino acid residues D634, D645, and E648, which further promotes the deubiquitination activity of USP10 and DNA damage response to form a positive feedback loop. PARP1 is highly expressed in breast cancer tissues and positively correlates with USP10 protein levels. Moreover, breast cancer cells treated with a USP10 inhibitor show increased sensitivity to PARP1 inhibitor both in vivo and in vitro. Overall, our results unravel that the deubiquitination-PARylation positive feedback loop of the USP10-PARP1 axis promotes DNA damage repair, which might contribute to the improvement of PARP1 inhibitor efficacy in breast cancer treatment.

Factors Affecting Genomic Testing in Prostate Cancer: Results From the Decision-Making, Experience, and Confidence In Determining Genomic Evaluation (DECIDE) Survey

PURPOSE

Genomic testing for prostate cancer (PCa) clinical management and hereditary cancer assessment has grown in clinical impact; however, challenges remain regarding optimal implementation and end-user confidence. The Decision-making, Experience, and Confidence In Determining Genomic Evaluation (DECIDE) survey was designed to collect information regarding utility and understanding of genomic testing from PCa health care providers, researchers, and stakeholders.

METHODS

The DECIDE survey was administered online from October 2022 to January 2023 with 18 multiple-response questions. Survey domains included self-confidence with ordering and interpreting germline and somatic genomic tests, process of testing and use of results, decision-making factors, and barriers to testing. Data were summarized by evaluating counts and percentages of responses, and the results were presented by descriptive statistics.

RESULTS

One hundred twenty-two participants completed the survey. The majority were medical oncologists (70%) and at academic medical centers (89%). Self-confidence was high in knowing indications for genomic testing (82% respondents) but lower in interpretation of results, especially from circulating tumor DNA (52%). Confidence varied in interpreting pathogenic variants (65% high confidence), variants of unknown significance (47%), and incidental findings from genomic tests (35%). Common barriers to testing were difficulty obtaining tissue (71%) and cost (35%). Testing utility was sometimes limited by inability to obtain the recommended treatment (33%). Most of the respondents (55%) agreed that lack of education and training of health care professionals regarding genomic testing is impeding clinical translation.

CONCLUSION

The DECIDE survey provided critical insights into challenges with genomic testing, from provider confidence in interpretating results to testing and practice barriers. The results inform next steps to further educate PCa providers and to collectively improve testing and result reporting for enhanced implementation of PCa genomic testing.

SETD1A-dependent EME1 transcription drives PARPi sensitivity in HR deficient tumour cells

BACKGROUND

Cells deficient in DNA repair factors breast cancer susceptibility 1/2 (BRCA1/2) or ataxia-telangiectasia mutated (ATM) are sensitive to poly-ADP ribose polymerase (PARP) inhibitors. Building on our previous findings, we asked how the lysine methyltransferase SETD1A contributed to PARP inhibitor-mediated cell death in these contexts and determined the mechanisms responsible.

METHODS

We used cervical, breast, lung and ovarian cancer cells bearing mutations in BRCA1 or ATM and depleted SETD1A using siRNA or CRISPR/Cas9. We assessed the effects of the PARPi Olaparib on cell viability, homologous recombination, and DNA repair. We assessed underlying transcriptional perturbations using RNAseq. We used The Cancer Genomics Atlas (TCGA) and DepMap to investigate patient survival and cancer cell characteristics.

RESULTS

Loss of SETD1A from both BRCA1-deficient and ATM-deficient cancer cells was associated with resistance to Olaparib, explained by partial restoration of homologous recombination. Mechanistically, SETD1A-dependent transcription of the crossover junction endonuclease EME1 correlated with sensitivity to Olaparib in these cells. Accordingly, when SETD1A or EME1 was lost, BRCA1 or ATM-mutated cells became resistant to Olaparib, and homologous recombination was partially restored.

CONCLUSIONS

Loss of SETD1A or EME1 drives cellular resistance to Olaparib in certain genetic contexts and may help explain why patients develop resistance to PARP inhibitors in the clinic.

DNA damage response deficiency enhances neuroblastoma progression and sensitivity to combination PARP and ATR inhibition

Sequencing of neuroblastoma (NB) tumors has revealed genetic alterations in genes involved in DNA damage response (DDR) pathways. However, roles for specific alterations of DDR genes in pediatric solid tumors remain poorly understood. To address this, mutations in the DDR pathway including Brca2, Atm, and Palb2 were incorporated into an established zebrafish MYCN transgenic model (Tg(dbh:EGFP-MYCN)). These mutations enhance NB formation and metastasis and result in upregulation of cell-cycle checkpoint and DNA damage repair signatures, revealing molecular vulnerabilities in DDR-deficient NB. DDR gene knockdown in zebrafish and human NB cells increases sensitivity to the poly(ADP-ribose) polymerase (PARP) inhibitor olaparib, and this effect is enhanced by inhibition of the ataxia telangiectasia and rad3-related (ATR) kinase. This work provides in vivo evidence demonstrating that alterations in certain DDR-pathway genes promote aggressive NB and supports combination PARP + ATR inhibitor therapy for NB patients with tumors harboring specific genetic alterations in DDR.

The Impact of Uncommon HRR Alterations as Predictors of Efficacy of PARP Inhibitors in Metastatic Castration-Resistant Prostate Cancer: A Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Metastatic castration-resistant prostate cancer (mCRPC) patients with BRCA1/2 mutations show significant responses to poly-ADP ribose polymerase inhibitors (PARPi), while the efficacy of these agents in patients with homologous recombination repair (HRR) gene alterations other than BRCA remains unclear.

OBJECTIVE

This meta-analysis aimed at assessing the efficacy of PARPi in mCRPC harboring alterations in four rare HRR genes (i.e. CDK12, PALB2, ATM, and CHEK2).

PATIENTS AND METHODS

Five randomised phase III trials (PROfound, PROpel, MAGNITUDE, TALAPRO-2, TRITON3) were selected through searching the Medline/PubMed, Cochrane Library, and ASCO Meeting abstracts. Data extraction followed the PRISMA statement. The primary endpoints, radiographic progression-free survival (rPFS) and overall survival (OS) with the relative 95% CI, were calculated using fixed- or random-effects methods, depending on the studies' heterogeneity. RevMan software for meta-analysis (v.5.2.3) was used.

RESULTS

PARPi significantly improved rPFS in mCRPC patients with CDK12 alterations (hazard ratio (HR) = 0.65; p = 0.02) without OS benefit. In patients with ATM, CHEK2, or PALB2 alterations, no significant benefit was observed in rPFS or OS. Due to the low incidence of these rare mutations, we grouped them into gene panels, revealing a significant rPFS advantage when CDK12+PALB2 (HR = 0.63; p = 0.009) were combined, and a similar benefit when including CHEK2 in the gene panel (HR = 0.69; p = 0.01).

CONCLUSION

CDK12 alterations could be considered as a predictive biomarker of rPFS benefit with PARPi. A gene panel grouping CDK12 and PALB2 with or without CHEK2 mutations could also enable prediction of rPFS benefit with PARPi.

Deep targeted sequencing of circulating tumor DNA to inform treatment in patients with metastatic castration-resistant prostate cancer

BACKGROUND

Intrinsic and acquired resistance to second-generation anti-androgens pose a significant clinical challenge in the treatment of metastatic castration-resistant prostate cancer (mCRPC). Novel biomarkers to predict treatment response and inform alternative treatment options are urgently needed.

METHODS

Deep targeted sequencing, with a prostate cancer-specific gene panel, was performed on circulating tumor DNA (ctDNA) and germline DNA from blood of mCRPC patients recruited in Denmark (n = 53), prior to starting first-line treatment with enzalutamide or abiraterone acetate, and for a subset of patients also at progression (n = 18). Likely clonal hematopoietic variants were filtered out. Genomic findings were correlated to clinical outcomes (PSA progression-free survival (PFS), overall survival (OS)). Intrinsic resistance candidate biomarkers were considered by enrichment analysis of nonresponders vs. responders. Genomic alterations at progression were considered as possible drivers of acquired resistance. Clinical actionability was assessed based on OncoKB and ESCAT.

RESULTS

Somatic alterations in PTEN, cell cycle regulators (CCND1, CDKN1B, CDKN2A, and RB1) and chromatin modulators (CHD1, ARID1A) were associated with significantly shorter PFS and OS, also after adjusting for ctDNA% in multivariate Cox regression analysis. The associations with poorer outcomes for alterations in PTEN and chromatin modulators were validated in an external dataset. Patients with primary resistance to enzalutamide/abiraterone had enrichment for BRAF amplification and CHD1 loss, while responders had enrichment for TMPRSS2 fusions. AR resistance mutations emerged in 22% of patients at progression. These were mutually exclusive with other alterations that may confer resistance (i.e., activating CTNNB1 mutations, combined TP53/RB1 loss). Clinically actionable alterations, primarily in homologous recombination repair genes, were found in 54.7% and 49.0% of patients (OncoKB and ESCAT, respectively), with few additional alterations detected at progression. Level I alterations were identified in 41.5% of patients employing OncoKB, however only in 13.2% based on ESCAT.

CONCLUSIONS

Our study identifies known and novel prognostic and predictive biomarker candidates in patients with mCRPC undergoing first-line treatment with enzalutamide or abiraterone acetate. It further provides real-world evidence of the significant potential of genomic profiling of ctDNA to inform treatment in this setting. Clinical trials are warranted to advance the implementation of ctDNA-based biomarkers into clinical practice.

Video Education Is an Acceptable Alternative to Pretest Genetic Counseling for Patients With Breast, Ovarian, Pancreatic, and Metastatic Prostate Cancer: Results From a Randomized Study

PURPOSE

With increased demand for cancer genetic testing (GT), providers are exploring alternative service delivery models such as video education (VE). We compare the uptake of GT among 250 patients with breast, ovarian, pancreatic, or metastatic prostate cancer randomly assigned to receive either pretest VE or a pretest visit with a genetic counselor (GC).

MATERIALS AND METHODS

Using a 3:1 ratio, 187 patients were randomly assigned to the VE arm and 63 patients to the GC arm. GT was arranged after participants either watched an informative video (VE arm) or met with a GC (GC arm). Satisfaction, knowledge, distress, decisional regret, and family communication were assessed as secondary study end points.

RESULTS

Participants were age 39-88 years with no significant demographic differences between the two arms. In the VE arm, 170 (90.95%) participants completed GT versus 49 (77.8%) in the GC arm (P = .01). The dropout rate before the pretest visit was higher in the GC arm compared with the VE arm: 10 (15.9%) versus 9 (4.8%). In the GC arm, 97.4% of participants felt all questions and concerns had been addressed compared with 66.9% of the VE arm (P < .0001). Of the 219 participants tested, 29 (13.2%) had a pathogenic or likely pathogenic variant.

CONCLUSION

In this study, there was high acceptance of VE and it led to better GT uptake compared with the GC arm. However, it will be important for programs using VE to build-in more opportunities for patients to ask questions. Pretest VE is a viable option for patients with cancer who need their germline genetic test results to help guide surgical and medical decisions.

5hmC-profiles in Puerto Rican Hispanic/Latino men with aggressive prostate cancer

Introduction

Puerto Rican (PR) Hispanic/Latino (H/L) men are an understudied population that has the highest prostate cancer (PCa) specific mortality among other Hispanic populations. Little information is known about the higher mortality in PR H/L men. It is thought that epigenetic changes in key genes may play a critical role in aggressive tumors.

Methods

We aimed to identify key 5-hydroxymethylcytosine (5hmC) changes in PR H/L men with aggressive PCa. We performed sequencing analysis using the 5hmC-enriched DNA from 22 prostate tumors and 24 adjacent normal FFPE samples.

Results

We identified 808 differentially methylated genes (DMGs) in tumors compared to adjacent normal tissues. These genes suggest key mechanisms, including upregulated signatures of negative Androgen Receptor (AR) regulation, Wnt/β-catenin pathway activation, and downregulation of tumor suppressor genes. Pathway analysis of DMGs demonstrated that DNA repair pathway was most upregulated in tumors. Since 5hmC abundance positively correlates with gene expression levels, we further investigated 808 DMGs in TCGA PCa gene expression data. Further, we identified 59 DMGs with significant gene expression changes in the same direction. Additionally, we identified 111 aggressiveness-related DMGs, of which, two hypomethylated genes (CCDC122, NUDT15) and four hypermethylated genes (PVT1, RPL30, TRMT12, UBR5) were found to be altered at transcriptomic level in a concordant manner in PR H/L PCa patients. Aberrant 5hmC and GE changes in these six genes were also associated with progression-free survival in the mixed PCa population.

Discussion

The 5hmC modifications and associated gene expression changes in these six genes could be linked to the highest prostate cancer (PCa)-specific mortality in PR H/L men. In conclusion, our study identified 59 DMGs showing concordant epigenetic and transcriptomic changes in tumor tissues and 111 DMGs showing association with aggressive PCa among PR H/L men. Our findings have significant implications for understanding these key genes' molecular mechanisms, which may drive PCa progression and mortality in this population. This will help in developing potential biomarkers or therapeutic targets for personalized treatment strategies in this high-risk subgroup. Future research will explore how these genes contribute to PCa-specific mortality through molecular analyses, with plans to validate them in a larger validation cohort.

PARP1: A comprehensive review of its mechanisms, therapeutic implications and emerging cancer treatments

The Poly (ADP-ribose) polymerase-1 (PARP1) enzyme is involved in several signalling pathways related to homologous repair (HR), base excision repair (BER), and non-homologous end joining (NHEJ). Studies demonstrated that the deregulation of PARP1 function and control mechanisms can lead to cancer emergence. On the other side, PARP1 can be a therapeutic target to maximize cancer treatment. This is done by molecules that can modulate radiation effects, such as DNA repair inhibitors (PARPi). With this approach, tumour cell viability can be undermined by targeting DNA repair mechanisms. Thus, treatment using PARPi represents a new era for cancer therapy, and even new horizons can be attained by coupling these molecules with a nano-delivery system. For this, drug delivery systems such as liposomes encompass all the required features due to its excellent biocompatibility, biodegradability, and low toxicity. This review presents a comprehensive overview of PARP1 biological features and mechanisms, its role in cancer development, therapeutic implications, and emerging cancer treatments by PARPi-mediated therapies. Although there are a vast number of studies regarding PARP1 biological function, some PARP1 mechanisms are not clear yet, and full-length PARP1 structure is missing. Nevertheless, literature reports demonstrate already the high usefulness and vast possibilities offered by combined PARPi cancer therapy.

Real-world treatment patterns and genetic testing in a metastatic castration-resistant prostate cancer setting in Europe

AIM

This study described treatment patterns, reasons for treatment, and homologous recombination repair mutation (HRRm) testing patterns in a real-world metastatic castration-resistant prostate cancer (mCRPC) population in Europe.

METHODS

Data were drawn from the Adelphi Prostate Cancer Disease Specific Programme™, a cross-sectional survey of physicians and patients conducted in France, Germany, Italy, Spain, and the United Kingdom, November 2022-May 2023. Physicians provided clinical characteristics, treatment and HRRm testing patterns, and reasons for treatment for eight consecutive patients with mCRPC. Most analyses were descriptive; treatment reasons were compared using Fisher's Exact test.

RESULTS

Physicians provided data for 1,737 mCRPC patients. Most patients (73%) were androgen receptor pathway inhibitor (ARPi)-naïve at first-line (1 L) mCRPC. Here, at 1 L mCRPC, 60% of patients received ARPi and 24% chemotherapy. Of those who received ARPi prior to mCRPC (n = 291), 60% received chemotherapy at mCRPC and 21% ARPi. Overall, 37% were HRRm tested. Treatment patterns, sequencing, reasons, and HRRm testing varied by country, physician specialty, and practice setting.

CONCLUSIONS

Treatment patterns generally followed guidelines. ARPi prescriptions prior to mCRPC were numerically higher than previously reported, however HRRm testing rates were still low meaning mCRPC patients may miss out on more effective targeted treatments.

Population Pharmacokinetics of Niraparib/Abiraterone Acetate Administered as Single-Agent Combination and Dual-Acting Tablets Plus Prednisone for Metastatic Castration-Resistant Prostate Cancer

INTRODUCTION

Use of niraparib and abiraterone acetate (AA; abiraterone prodrug) in patients with metastatic castration-resistant prostate cancer (mCRPC) targets two oncogenic drivers: homologous recombination repair (HRR) gene alterations and the androgen-receptor axis. Fixed-dose niraparib/AA combination is available as regular-strength dual-action tablets (RS-DAT; 200 mg/1000 mg) and low-strength DAT (LS-DAT; 100 mg/1000 mg, enabling niraparib dose reduction). We characterized the population pharmacokinetics (PPK) of niraparib and abiraterone, administered alone or in combination, in patients with mCRPC.

METHODS

PPK modeling and covariate analysis using a non-linear mixed-effect modeling approach were conducted using pooled PK data from patients with mCRPC enrolled in the BEDIVERE (NCT02924766), GALAHAD (NCT02854436), QUEST (NCT03431350), and MAGNITUDE (NCT03748641) studies and in a study of relative bioavailability for LS-DAT and bioequivalence for RS-DAT. In all but GALAHAD (niraparib monotherapy), AA + prednisone was given alone or with niraparib. Overall, 9935 and 6289 niraparib and abiraterone plasma PK samples from 916 and 954 patients, respectively, were available.

RESULTS

Niraparib and abiraterone PK were adequately described by an open two-compartment disposition model with linear elimination, with a zero-order rate of drug release into the depot compartment followed by first-order absorption (via two transit compartments for abiraterone) into the central compartment. For niraparib, identified covariates were creatinine clearance on apparent oral clearance; LS-DAT on zero-order drug-release duration and apparent oral bioavailability; HRR status on apparent oral clearance; race on first-order absorption-rate constant, intercompartmental clearance, and peripheral compartment volume of distribution. Covariate effects had no clinically relevant impact on niraparib exposure, warranting no dose adjustments. For abiraterone, RS-DAT was the only newly identified covariate on apparent oral bioavailability, first-order absorption-rate constant, and zero-order drug-release duration; however, effect magnitude was deemed not clinically relevant.

CONCLUSION

PPK analyses support the selected clinical dosage of RS-DAT (200-mg niraparib/1000-mg AA) plus 10-mg prednisone daily for treating patients with mCRPC and HRR gene alterations.

Deciphering the mechanisms of PARP inhibitor resistance in prostate cancer: Implications for precision medicine

Prostate cancer is a leading malignancy among men. While early-stage prostate cancer can be effectively managed, metastatic prostate cancer remains incurable, with a median survival of 3-5 years. The primary treatment for advanced prostate cancer is androgen deprivation therapy (ADT), but resistance to ADT often leads to castrationresistant prostate cancer (CRPC), presenting a significant therapeutic challenge. The advent of precision medicine has introduced promising new treatments, including PARP inhibitors (PARPi), which target defects in DNA repair mechanisms in cancer cells. PARPi have shown efficacy in treating advanced prostate cancer, especially in patients with metastatic CRPC (mCRPC) harboring homologous recombination (HR)-associated gene mutations. Despite these advancements, resistance to PARPi remains a critical issue. Here, we explored the primary mechanisms of PARPi resistance in prostate cancer. Key resistance mechanisms include homologous recombination recovery through reverse mutations in BRCA genes, BRCA promoter demethylation, and non-degradation of mutated BRCA proteins. The tumor microenvironment and overactivation of the base excision repair pathway also play significant roles in bypassing PARPi-induced synthetic lethality. In addition, we explored the clinical implications and therapeutic strategies to overcome resistance,emphasizing the need for precision medicine approaches. Our findings highlight the need for comprehensive strategies to improve PARPi sensitivity and effectiveness,ultimately aiming to extend patient survival and improve the quality of life for those with advanced prostate cancer. As our understanding of PARPi resistance evolves, more diverse and effective individualized treatment regimens will emerge.

Off-label use of olaparib in uncommon tumor locations in patients with impaired homologous recombination genes

OBJECTIVE

To describe the effectiveness and safety of olaparib off-label indications in patients with impaired homologous recombination genes and solid tumors different than those authorized.

METHODS

A single-center, observational and retrospective study including patients treated with olaparib for off-label use. The main variables were patient characteristics, prior therapies, response to therapy, progression-free survival, overall survival and adverse events.

RESULTS

A total of 6 patients were included. All patients had metastases and received 3 or more lines of prior treatment. The primary tumor locations and mutations were partner and localizer of BRCA2 (PALB2) intrahepatic cholangiocarcinoma, ataxia telangiectasia mutated (ATM) non-small cell lung adenocarcinoma, somatic breast cancer gene (sBRCA2) colorectal cancer, germinal breast cancer gene 2 (gBRCA2) breast neuroendocrine tumor, gBRCA2 ampullary cancer and gBRCA2 pancreatic neuroendocrine tumor. At the end of the study, one patient was still receiving olaparib showing more than 25 months of sustained stable disease response. No novel toxicities were observed besides those included in the product information.

CONCLUSIONS

There is limited published evidence on the use of olaparib in patients harboring pathogenic variants other than breast cancer genes, like PALB2 and ATM and conditions different than those authorized such as digestive tract, neuroendocrine and lung tumors. Further research is to assess the efficacy of olaparib in these patients.

Next-generation sequencing for guiding matched targeted therapies in people with relapsed or metastatic cancer

BACKGROUND

Matched targeted therapies (MTT) given alone or in combination with systemic anti-cancer therapies have delivered proven survival benefit for many people with newly diagnosed cancer. However, there is little evidence of their effectiveness in the recurrent or late-stage setting. With this uncertainty, alongside the perception that late-stage cancers are too genetically heterogenous or too mutationally diverse to benefit from matched targeted therapies, next-generation sequencing (NGS) of tumours in people with refractory cancer remains a low priority. As a result, next-generation sequencing testing of recurrent or late-stage disease is discouraged. We lack evidence to support the utility of next generation sequencing in guiding matched targeted therapies in this setting.

OBJECTIVES

To evaluate the benefits and harms of matched targeted therapies in people with advanced cancers in randomised controlled trials.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, ClinicalTrials.gov, and the World Health Organisation International Clinical Trials Registry Platform (WHO-ICTRP) search portal up to 30th October 2024. We also screened reference lists of included studies and also the publications that cited these studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that had enroled participants with advanced/refractory solid or haematological cancers who had progressed through at least one line of standard anti-cancer systemic therapy. To be eligible, all participants should have received matched targeted therapy based on next-generation sequencing carried out on their tumour (tumour tissue, blood or bone marrow).

DATA COLLECTION AND ANALYSIS

We systematically searched medical databases (e.g. MEDLINE, Embase) and trial registers for randomised controlled trials (RCTs). Outcomes of interest were progression-free survival (PFS), overall survival (OS), overall response rates (ORR), serious (grade 3 or 4) adverse events (AEs) and quality of life (QOL). We used a random-effects model to pool outcomes across studies and compared predefined subgroups using interaction tests. Grading of Recommendations Assessment, Development and Evaluation (GRADE) assessment of certainty was used to evaluate the quality of evidence.

MAIN RESULTS

We identified a total of 37 studies, out of which 35 studies (including 9819 participants) were included in the meta-analysis. All included studies compared a matched targeted therapy intervention to standard-of-care treatment, non-matched targeted therapies or no treatment (best supportive care): Matched targeted therapy versus standard-of-care treatment Matched targeted therapy (MTT) compared with standard systematic therapy probably reduces the risk of disease progression by 34% (hazard ratio (HR) = 0.66, 95% confidence interval (CI) 0.59 to 0.74; 14 studies, 3848 participants; moderate-certainty evidence). However, MTT might have little to no difference in risk of death (HR = 0.85, 95% CI 0.75 to 0.97; 14 studies, 3848 participants; low-certainty evidence) and may increase overall response rates (low-certainty evidence). There was no clear evidence of a difference in severe (grade 3/4) adverse events between matched targeted therapy and standard-of-care treatment (low-certainty evidence). There was limited evidence of a difference in quality of life between groups (very low-certainty of evidence). Matched targeted therapy in combination with standard-of-care treatment versus standard-of-care treatment alone Matched targeted therapy in combination with standard-of-care treatment compared with standard-of-care treatment alone probably reduces the risk of disease progression by 39% (HR = 0.61, 95% CI 0.53-0.70, 14 studies, 2,637 participants; moderate-certainty evidence) and risk of death by 21% (HR = 0.79, 95% CI 0.70 to 0.89; 11 studies, 2575 participants, moderate-certainty evidence). The combination of MTT and standard-of-care treatment may also increase overall response rates (low-certainty evidence). There was limited evidence of a difference in the incidence of severe adverse events (very low-certainty evidence) and quality of life between the groups (very low-certainty of evidence). Matched targeted therapy versus non-matched targeted therapy Matched targeted therapy compared with non-matched targeted therapy probably reduces the risk of disease progression by 24% (HR = 0.76, 95% CI 0.64 to 0.89; 3 studies, 1568 participants; moderate-certainty evidence) and may reduce the risk of death by 25% (HR = 0.75, 95% CI 0.65 to 0.86, 1307 participants; low-certainty evidence). There was little to no effect on overall response rates between MTT and non-MTT. There was no clear evidence of a difference in overall response rates (low-certainty evidence) and severe adverse events between MTT and non-MTT (low-certainty evidence). None of the studies comparing MTT and non-MTT reported quality of life. Matched targeted therapy versus best supportive care Matched targeted therapy compared with the best supportive care (BSC) i.e. no active treatment probably reduces the risk of disease progression by 63% (HR 0.37, 95% CI 0.28 to 0.50; 4 studies, 858 participants; moderate-certainty evidence). There was no clear evidence of a difference in overall survival between groups (HR = 0.88, 95% CI 0.73 to 1.06, 3 studies, 783 participants; low-certainty evidence). There was no clear evidence of a difference in overall response rates (very low-certainty of evidence) and incidence of severe adverse events (very low-certainty of evidence) between the groups. Quality of life was reported in a single study but did not provide composite scores. Risk of bias The overall risk of bias was judged low for eight studies, unclear for two studies, and the remaining 27 studies were high risk.

AUTHORS' CONCLUSIONS

Matched targeted therapies guided by next-generation sequencing in people with advanced cancer prolongs the time before cancer progresses compared to standard therapies. However, there is limited evidence to suggest that it prolongs overall survival, improves the quality of life or increases adverse events. Importantly, this review supports equitable access to next-generation sequencing technology for all people with advanced cancer and offers them the opportunity to access genotype-matched targeted therapies.

The combination of poly(ADP-ribose) polymerase inhibitor and statin inhibits the proliferation of human castration-resistant and taxane-resistant prostate cancer cells in vitro and in vivo

BACKGROUND

Olaparib exhibits antitumor effects in castration-resistant prostate cancer patients with germline mutations in DNA repair genes. We previously reported that simvastatin reduced the expression of DNA repair genes in PC-3 cells. The efficacy of combination therapy using olaparib and simvastatin as "BRCAness" in castration-resistant and taxane-resistant prostate cancers was evaluated in this study.

METHODS

PC-3, LNCaP, and 22Rv1 human prostate cancer cell lines were used to develop androgen-independent LNCaP cells (LNCaP-LA). mRNA and protein expression levels were evaluated by quantitative real-time polymerase chain reaction and western blot analysis, respectively. Cell viability was determined using the MTS assay and cell counts. All evaluations were performed on cells treated with simvastatin with or without olaparib.

RESULTS

The mRNA levels of BRCA1, BRCA2, RAD51, FANCD2, FANCG, FANCA, BARD1, RFC3, RFC4, and RFC5, which are known DNA repair genes, were downregulated by simvastatin in androgen-independent prostate cancer cells, such as PC-3, LNCaP-LA, and 22Rv1 cells. In contrast, the expression of all these genes remained unchanged in androgen-dependent LNCaP cells following treatment with simvastatin. Furthermore, simvastatin increased the expression of above stated genes in normal prostate stromal cells (PrSC). The reduction in BRCA1 and BRCA2 expression following siRNA transfection increased the cytocidal effects of Olaparib in PC-3 and LNCaP-LA cells. The combination of olaparib and simvastatin further inhibited cell proliferation compared to monotherapy with either drug in PC-3, 22Rv1, and LNCaP-LA cells but not in PrSC cells. In a 22Rv1-derived mouse xenograft model, the combination of olaparib and simvastatin enhanced the inhibition of cell proliferation. Moreover, we established a 22Rv1 cell line with acquired resistance to Cabazitaxel (22Rv1-CR). In 22Rv1-CR cells, simvastatin also decreased the expression of BRCA1, BRCA2, and FANCA, and the combination of olaparib and simvastatin further enhanced the inhibition of cell proliferation compared with treatment with either of the drugs alone.

CONCLUSIONS

Simvastatin altered the expression of several genes associated with DNA repair in castration-resistant and taxane-resistant prostate cancer cells. The combination of poly (ADP-ribose) polymerase inhibitors and drugs that decrease DNA repair gene expression can potentially affect castration-resistant and taxane-resistant prostate cancer growth.

Exploring therapeutic applications of PTEN, TMPRSS2:ERG fusion, and tumour molecular subtypes in prostate cancer management

Background

Prostate cancer is defined by the suppression of genes that suppress tumours and the activation of proto-oncogenes. These are the hallmarks of prostate cancer, and they have been linked to numerous genomic variations, which lead to unfavourable treatment outcomes. Prostate cancer can be categorised into various risk groups of tumour molecular subtypes grounded in the idea of genomic structural variations connected to TMPRSS2:ERG fusion and loss of PTEN. Research suggests that certain genomic alterations may be more prevalent or exhibit different patterns in prostate cancer tumours across populations. Studies have reported a higher frequency of PTEN loss and TMPRSS2:ERG fusion in prostate tumours of Black/African American men, which may contribute to the more aggressive nature of the disease in this population. Thus, therapeutically important information can be obtained from these structural variations, including correlations with poor prognosis and disease severity.

Methods

Peer-reviewed articles from 1998 to 2024 were sourced from PubMed and Google Scholar. During the review process, the following search terms were employed: "Tumour suppressor genes OR variations OR alterations OR oncogenes OR diagnostics OR ethnicity OR biomarkers OR prostate cancer genomics OR prostate cancer structural variations OR tumour and molecular subtypes OR therapeutic implications OR immunotherapy OR immunogenetics."

Results

There was a total of 13,012 results for our search query: 5,903 publications from Google Scholar with the patent and citation unchecked filer options, and 7127 articles from PubMed with the abstract, free full text, and full-text options selected. Unpublished works were not involved. Except for four articles published between 1998 and 1999, all other selected articles published in 2000 and later were considered. However, papers with irrelevant information or redundant or duplicate content were not chosen for this review. Thus, 134 met the inclusion criteria and were ultimately retained for this review.

Conclusion

This review extracted 134 relevant articles about genomic structure variations in prostate cancer. Our findings demonstrate the importance of PTEN and TMPRSS2:ERG fusion and tumour molecular subtyping in prostate cancer precision medicine.

"Hope at a better chance": perspectives on genetic counseling and testing among black individuals with prostate cancer

Black individuals have the highest prostate cancer (PCa) incidence and mortality rates of any racial or ethnic group. Racial disparities persist in the understanding and uptake of genetics services, while the perspectives of Black individuals with PCa regarding genetic counseling and germline genetic testing for inherited cancer risk (GC/GT) remains understudied. This qualitative study explored attitudes, facilitators, and barriers to awareness, interest, and uptake of GC/GT among Black individuals with PCa. Eight individuals who self-identified as African American and/or Black with a personal history of PCa participated in individual telephone interviews using a semi-structured interview guide. Interview transcripts were analyzed using both an inductive and deductive coding approach, constant comparison, and selective coding. Five major themes were identified: (1) uncertainty surrounding personal relevance of GC/GT, (2) family influence and impact of GC/GT, (3) healthcare providers and institutions as gatekeepers of GC/GT, (4) community identity, influence, and impact of GC/GT, and (5) systemic barriers to GC/GT exemplify larger structural constraints. A key finding was the influence of community, a collective identity among Black individuals and a desire to benefit the Black community, in motivating research participation and pursuit of GC/GT to lessen racial disparities in PCa. Individual, interpersonal, institutional, community, and structural factors are both barriers and facilitators to awareness, interest, and uptake of GC/GT. Multilevel interventions such as communicating personal, familial, and community implications of GC/GT, improving patient-provider relationships and genetics education, and addressing systemic barriers are necessary to increase efficacy, utility, and equity in GC/GT.

Predictive biomarkers for the efficacy of PARP inhibitors in ovarian cancer: an updated systematic review

BACKGROUND

PARP inhibitors are effective in treating ovarian cancer, especially for BRCA1/2 pathogenic variant carriers and those with HRD (homologous recombination deficiency). Concerns over toxicity and costs have led to the search for predictive biomarkers. We present an updated systematic review, expanding on a previous ESMO review on PARP inhibitor biomarkers.

METHODS

Following ESMO's 2020 review protocol, we extended our search to March 31, 2023, including PubMed and clinical trial data. We also reviewed the reference lists of review articles. We conducted a meta-analysis using a random-effects model to evaluate hazard ratios and assess the predictive potential of biomarkers and the effectiveness of PARP inhibitors in survival.

RESULTS

We found 375 articles, 103 of which were included after screening (62 primary research, 41 reviews). HRD remained the primary biomarker (95%), particularly BRCA1/2 variants (77%). In the non-HRD category, six articles (10%) introduced innovative biomarkers, including ADP-ribosylation, HOXA9 promoter methylation, patient-derived organoids, KELIM, and SLFN11.

DISCUSSION

Prospective assessment of real-time homologous recombination repair via nuclear RAD51 levels shows promise but needs validation. Emerging biomarkers like ADP-ribosylation, HOXA9 promoter methylation, patient-derived organoids, KELIM, and SLFN11 offer potential but require large-scale validation.

Multi-gene risk score for prediction of clinical outcomes in treatment-naïve metastatic castrate-resistant prostate cancer

BACKGROUND

To determine the performance of a multi-gene copy number variation (MG-CNV) risk score in metastatic tissue and plasma biospecimens from treatment-naïve metastatic castration-resistant prostate cancer (mCRPC) patients for prediction of clinical outcomes.

METHODS

The mCRPC tissue and plasma cell-free DNA (cfDNA) biospecimen sequencing results obtained from publicly accessed cohorts in dbGaP, cBioPortal, and an institutional mCRPC cohort were used to develop a MG-CNV risk score derived from gains in AR, MYC, COL22A1, PIK3CA, PIK3CB, NOTCH1 and losses in TMPRSS2, NCOR1, ZBTB16, TP53, NKX3-1 in independent cohorts for determining overall survival (OS), progression-free survival (PFS) to first-line androgen receptor pathway inhibitors (ARPIs). The range of the risk scores for each cohort was dichotomized into "high-risk" and "low-risk" groups and association with OS/PFS determined. Univariate and multivariable Cox proportional hazards regressions were applied for survival analyses (P < .05 for statistical significance).

RESULTS

Of 1137 metastatic tissue-plasma biospecimens across all cohorts, 699/1137 were treatment-naive mCRPC (235/699 metastatic tissue; 464/699 plasma-cfDNA), and 311/1137 were matched tissue-cfDNA pairs. In multivariable analysis, the MG-CNV risk score derived from metastatic tissue or in cfDNA was statistically significantly associated with OS with high score associated with short survival (hazard ratio = 2.65, confidence interval = 1.99 to 3.51; P = 1.35-11) and shorter PFS to ARPIs (median PFS of 7.8 months) compared with 14 months in patients with low-risk score.

CONCLUSIONS

A molecular risk score in treatment-naïve mCRPC state obtained either in metastatic tissue or cfDNA predicts clinical survival outcomes and offers a tumor biology-based tool to design biomarker-based enrichment clinical trials.

Germline genetic testing for prostate cancer: Ordering trends in the era of expanded hereditary cancer screening recommendations

PURPOSE

The availability of targeted therapies for advanced prostate cancer led to the expansion of national guidelines recommending germline genetic testing. The aim of this study was to describe recent trends in germline test ordering patterns for patients with prostate cancer.

MATERIALS AND METHODS

A retrospective cohort analysis of patients with prostate cancer who underwent germline testing through a single commercial laboratory (Invitae Corporation) between 2015-2020 was performed. Ordering trends between provider medical specialties were compared. Our primary hypothesis was that the proportion of tests ordered by urologists would increase over time.

RESULTS

In total, 17,256 prostate cancer patients underwent germline genetic testing; 14,400 patients had an ordering provider with an associated medical specialty and were included in the final comparison cohort. Total prostate cancer patients undergoing germline testing increased quarterly from 21 in Q2 of 2015 to 1,509 in Q3 of 2020. The proportion of tests ordered by urologists increased from 0% in Q2 2015 to 8.3% in Q3 2020 (P < 0.001). Compared to medical genetics, medical oncology, and other specialties, urology ordered more tests for patients under 70 years old (66% vs 51%-55%, P <0.004) and for patients who reported negative family history (25% vs 12%-20%, P = 0.012).

CONCLUSIONS

As awareness and indications for germline testing continue to expand, aggregate ordering volume is increasing, and urologists are becoming more involved in facilitating testing. This highlights the continued importance of educating urologists on the indications for and implications of germline genetic testing, as well as providing tools to support implementation.

Increased Synthetic Cytotoxicity of Combinatorial Chemoradiation Therapy in Homologous Recombination Deficient Tumors

PURPOSE

Homologous recombination deficient (HRD) tumors are exquisitely sensitive to platinum-based chemotherapy and when combined with radiation therapy (RT), leads to improved overall survival in multiple cancer types. Whether a subset of tumors with distinct molecular characteristics demonstrate increased benefit from cisplatin and RT (c-RT) is unclear. We hypothesized that HRD tumors, whether associated with BRCA mutations or genomic scars of HRD, exhibit exquisite sensitivity to c-RT, and that HRD may be a significant driver of c-RT benefit.

METHODS AND MATERIALS

Sensitivity to c-RT was examined using isogenic and sporadic breast cancer cell lines. HRD was assessed using 4 assays: RT-induced Rad51 foci, a DR-GFP reporter assay, a genomic scar score (large-scale state transitions [LST]), and clonogenic survival assays. Whole-genome sequencing of 4 breast tumors from a phase 2 clinical trial of neoadjuvant c-RT in triple-negative breast cancer was performed and HRD was defined using HRDetect.

RESULTS

BRCA1/2 deficient cell lines displayed functional HRD based on the Rad51 functional assay, with c-RT to RT or cisplatin interaction ratios (IR) of 1.11 and 26.84 for the BRCA1 isogenic pair at 2 μM cisplatin and 6 Gy, respectively. The highest LST lines demonstrated HRD and synthetic cytotoxicity to c-RT with IR at 2 Gy and cisplatin 20 μM of 7.50, and the lowest LST line with IR of 0.65. Of 4 evaluable patients in the phase 2 trial, one achieved a pathologic complete response with corresponding HRD based on multiple genomic scar scores including HRDetect and LST scores, compared with patients without a pathologic complete response.

CONCLUSIONS

HRD breast cancers, whether identified by BRCA1/2 mutation status, functional tests, or mutational signatures, appear to be significantly more sensitive to c-RT compared with isogenic controls or tumors without HRD mutational signatures. HRD tumors may be exquisitely sensitive to c-RT which warrants further clinical investigation to guide a precision oncology approach.

Germline and Somatic Genomic Testing for Metastatic Prostate Cancer: ASCO Guideline

PURPOSE

To evaluate evidence on germline and somatic genomic testing for patients with metastatic prostate cancer and provide recommendations.

METHODS

A systematic review by a multidisciplinary panel with patient representation was conducted. The PubMed database was searched from January 2018 to May 2024. Articles were selected for inclusion if they reported on patients with metastatic prostate cancer who received a germline or somatic genomic test and/or made comparisons between those tests, reported detection rates, prognostic information, or treatment implications.

RESULTS

A total of 1,713 papers were identified in the literature search. After applying the eligibility criteria, 14 remained: eight systematic reviews and six clinical trials.

RECOMMENDATIONS

Patients with metastatic prostate cancer should undergo both germline and somatic DNA sequencing using panel-based assays. These tests can guide the use of poly(ADP-ribose) polymerase inhibitors, which have a survival benefit in metastatic castration-resistant prostate cancer. In addition, germline testing may have screening implications for additional cancers for patients and cascade testing implications for family members. The data supporting when to perform repeat testing and optimal tissue type to use (eg, primary tumor v metastatic biopsy versus circulating tumor DNA [ctDNA] testing) are more limited, but this panel recommends considering retesting in patients whose results were previously negative or uninformative, and to consider either a metastatic biopsy or ctDNA when a significant change in clinical status occurs. Next-generation genomic sequencing findings that are associated with prognostic only (and not predictive) value should not be used to guide treatment outside of a clinical trial.Additional information is available at www.asco.org/genitourinary-cancer-guidelines.

Ancestry-Specific DNA Damage Repair Gene Mutations and Prostate Cancer

This review is intended to reflect the currently available literature on both clinically significant germline mutations in DNA damage repair (DDR) genes as well as the importance of ancestral diversity in the pathogenesis of prostate cancer (PCa). The second most prevalent cancer worldwide in men is PCa, causing significant morbidity and mortality in its advanced stage. Emerging data highlight the substantial role of germline mutations of DDR genes in PCa pathogenesis, especially in progression to aggressive forms of the disease. Germline genetic testing is recognized as a necessary tool for efficient, individualized patient care. NCCR guidelines recommend inquiring about the family history of PCa and known germline variants and, if indicated, proceeding with germline multigene testing followed by post-test genetic counseling. Depending on the germline mutations in HR repair genes or in MMR genes, specific treatment options may provide clinical benefit. We will discuss specific germline mutations that are involved in PCa progression and prognosis in racially diverse populations.

Homologous recombination repair status in metastatic prostate cancer by next-generation sequencing and functional immunofluorescence

Metastatic prostate cancer (mPC) is enriched for homologous recombination repair (HRR) gene alterations, which have prognostic and predictive value. Routine clinical implementation of next-generation sequencing (NGS) is still limited. We investigated the association between genomic and functional loss of HRR, using NGS and RAD51 immunofluorescence (RAD51-IF) in 219 primary or metastatic biopsies from 187 patients with stage IV prostate cancer. NGS showed frequent genomic alterations in TP53 (40%), AR (15%), PTEN (14%), FOXA1 (12%), MYC (10%), BRCA2 (9%), ATM (8%), and BRCA1 (2%). We pursued RAD51-IF in 206 samples; of those, 139/206 (67%) were evaluable. 21% of samples had RAD51-low score compatible with HRR deficiency (HRD). RAD51-IF showed high sensitivity (71%) and specificity (86%) for BRCA1/2 alterations. Patients with RAD51-low scores experienced longer progression-free survival (PFS) on poly(ADP-ribose) polymerase inhibitors (PARPi) or platinum chemotherapy. RAD51-IF is feasible in routine clinical samples from patients with mPC and is associated with clinically relevant HRR gene alterations.

Prevalence of Somatic BReast CAncer Gene (BRCA) 1 and 2 Pathogenic Variants in Portuguese Metastatic Prostate Cancer Patients

Currently, poly adenosine diphosphate ribose polymerase inhibitors are used to treat metastatic prostate cancer (mPC) patients with somatic or germline pathogenic variants in genes related to homologous recombination repair deficiency. Testing for these variants is thus advisable, as test results can have implications for systemic treatment. Of those genes, the most relevant in clinical practice are BReast CAncer gene (BRCA) 1and 2. Despite no published data regarding the prevalence of germline and somatic variants in mPC Portuguese patients, practitioners have long felt that the prevalence of somatic BRCA1/2 variants in these patients is much lower than in previously studied populations. To estimate the prevalence of pathogenic BRCA1/2 variants, we fit a Bayesian hierarchical model with data from metastatic patients subject to universal testing and data from international cohorts. All 42 patients tested were negative for somatic BRCA1/2 pathogenic variants. This posterior estimate for the prevalence is 3.1% (95% credibility interval 0.3-10.3%), and we found a large dispersion between the prevalences of different populations. This estimate is much lower than the estimates in other published cohorts. We believe that testing recommendations should be tailored to country-specific prevalence. As such, we will continue to perform universal testing in an investigational context to decrease the uncertainty in our estimates and better establish the role of universal somatic testing in the Portuguese population.

Novel Intraprostatic Magnetic Resonance-Guided Implantation of Multidrug-Eluting Microdevice for Testing of Systemic Therapy Agents In Situ: Proof of Concept in Intermediate-Risk and High-Risk Prostate Cancer

PURPOSE

The purpose of this study was to assess safety and feasibility of percutaneous magnetic resonance-guided placement of an implantable microdevice (IMD) to evaluate in situ intratumor response to multiple pharmacologic agents in men with intermediate-risk and high-risk localized prostate cancer.

MATERIALS AND METHODS

Biocompatible IMDs measuring 750 µm in diameter and 5 mm in length were prepared with 20 reservoirs containing candidate drug and drug combinations including second-generation androgen inhibitors, PARP inhibitors, PD-1 inhibitors, and conventional chemotherapy. Men with intermediate-risk or high-risk localized prostate cancer and MRI-visible lesions were enrolled. Up to 4 IMDs were placed using a transperineal approach into MRI-visible tumors 2 days before planned radical prostatectomy. After radical prostatectomy, the IMDs and a small segment of surrounding tumor tissue were removed and sectioned, stained, and analyzed for tissue drug response by a variety of pharmacodynamic markers.

RESULTS

Fourteen patients were enrolled: 7 (50%) with intermediate-risk and 7 (50%) with high-risk localized prostate cancer. A total of 53 IMDs were implanted (mean 3.8 per patient), and 49 IMDs (92%) were successfully retrieved. All men underwent uncomplicated robotic-assisted radical prostatectomy and bilateral pelvic lymph node dissection 2 days after IMD placement. There were no severe adverse events. Pathological examination of the tissues adjacent to the IMDs demonstrated differential drug response within patients and between patients. Limitations include small sample size.

CONCLUSIONS

A multidrug IMD can be safely placed percutaneously into MRI-visible lesions before radical prostatectomy, enabling assessment of tumor-specific local response to multiple agents simultaneously within the tumor's normal stromal environment to guide targeted systemic therapy.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT04399876.

Protein kinase D1 mitigation against etoposide induced DNA damage in prostate cancer is associated with increased α-Catenin

BACKGROUND

The E-cadherin, α- and β-Catenin interaction at the cell adherens junction plays a key role in cell adhesion; alteration in the expression and function of these genes are associated with disease progression in several solid tumors including prostate cancer. The membranous β-Catenin is dynamically linked to the cellular cytoskeleton through interaction with α-Catenin at amino acid positions threonine 120 (T120) to 151 of β-Catenin. Nuclear presence of α-Catenin modulates the sensitivity of cells to DNA damage. The objective of this study is to determine the role of α-Catenin and protein kinase D1 (PrKD1) in DNA damage response.

METHODS

Prostate cancer cells; LNCaP, LNCaP (Sh-PrKD1; silenced PrKD1), C4-2 and C4-2 PrKD1 were used for various sets of experiments to determine the role of DNA damage in PrKD1 overexpression and silencing cells. These cells were treated with compound-10 (100 nM) and Etoposide (30 µM), total cell lysates, cytosolic and nuclear fractions were prepared to observe various protein expressions. We performed single cell gel electrophoresis (COMET assay) to determine the etoposide induce DNA damage in C4-2 and C4-2 PrKD1 cells. The animal experiments were carried out to determine the tolerability of compound-10 by mice and generate preliminary data on efficacy of compound-10 in modulating the α-Catenin and PrKD1 expressions in inhibiting tumor progression.

RESULTS

PrKD1, a novel serine threonine kinase, phosphorylates β-Catenin T120. In silico analysis, confirmed that T120 phosphorylation alters β- to α-Catenin binding. Forced expression of PrKD1 in prostate cancer cells increased β- and α-Catenin protein levels associated with reduced etoposide induced DNA damage. Downregulation of α-Catenin abrogates the PrKD1 mitigation of DNA damage. The in vitro results were corroborated in vivo using mouse prostate cancer patient derived xenograft model by inhibition of PrKD1 kinase activity with compound-10, a selective PrKD inhibitor, demonstrating decreased total β- and α-Catenin protein levels, and β-Catenin T120 phosphorylation.

CONCLUSIONS

Alteration in DNA damage response pathways play major role in prostate cancer progression. The study identifies a novel mechanism of α-Catenin dependent DNA damage mitigation role for PrKD1 in prostate cancer.

First-In-Human Dose Finding Study of Venadaparib (IDX-1197), a Potent and Selective PARP Inhibitor, in Patients With Advanced Solid Tumors

BACKGROUND

Venadaparib, a novel poly (ADP-ribose) polymerase (PARP) inhibitor, has demonstrated high PARP-1/2 selectivity over other PARP family members and exhibited strong PARP-trapping activity, effectively inhibiting tumor growth in homologous recombination deficient (HRD) cancer in vitro and in vivo.

METHODS

This phase 1, dose-finding study evaluated the safety, tolerability, pharmacokinetics, pharmacodynamics and anticancer efficacy of venadaparib as monotherapy in patients with advanced solid tumors that progressed after standard-of-care therapy. The study employed a conventional 3+3 design, with doses ranging from 2 mg/d to 240 mg/d.

RESULTS

Among the 32 enrolled patients, the most common tumor types were breast (16 patients) and ovarian (12 patients) cancers. No dose-limiting toxicities (DLTs) were observed up to 240 mg/d. The most frequent grade 3 or 4 adverse events were anemia (50%), neutropenia (22%) and thrombocytopenia (6%). Tumor shrinkage by Response Evaluation Criteria in Solid Tumours (RECIST) was observed at doses ≥ 40 mg/d, regardless of BRCA mutation status.Two partial responses out of four ovarian cancer patients receiving venadaparib ≥ 40 mg/d were reported. Clinical benefit, defined as stable disease or partial response, was observed at the lowest tested dose. Venadaparib exhibited ≥ 90% PAR inhibitory effect in pharmacodynamic analysis from 10 mg/d based on tumor samples. The recommended phase 2 dose (RP2D) was defined as 160 mg once daily.

CONCLUSIONS

Further studies are warranted to explore efficacy and safety of venadaparib in other tumor types and in combination with various agents, as well as to explore relevant biomarkers. (ClinicalTrials.gov ID: NCT03317743).

Incidence and Risk of Thromboembolic and Cardiovascular Adverse Events with PARP Inhibitor Treatment in Patients with Metastatic Castration-resistant Prostate Cancer: A Systematic Review and Safety Meta-analysis

Background and objective

PARP inhibitor (PARPi) treatment is an effective option for patients with metastatic castration-resistant prostate cancer (mCRPC). There are few data on the cardiovascular and thromboembolic safety of these agents in mCRPC, as cardiovascular and thromboembolic adverse events (AEs) are uncommon. Our aim was to analyze the incidence and risk of major adverse cardiovascular events (MACEs), thromboembolic events, and hypertension with PARPi therapy in mCRPC.

Methods

We conducted a systematic review and meta-analysis in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. We systematically searched the PubMed, EMBASE, and Cochrane databases and the American Society of Clinical Oncology and European Society of Medical Oncology meeting abstracts for clinical trials on PARPi use in mCRPC up to March 31, 2024. We analyzed the pooled incidence of all-grade and high-grade MACEs, thromboembolic events, and hypertension, and calculated risk ratios (RRs) for PARPi versus non-PARPi treatment.

Key findings and limitations

We included 11 phase 2 or 3 trials in our meta-analysis. Hypertension was the most common AE for both any-grade (17.2%) and high-grade (9.3%) events. In comparison to other treatments, PARPi was associated with significantly higher risk of high-grade MACEs (RR 2.03; p = 0.03) and thromboembolic events (RR 2.15; p = 0.002), especially venous thromboembolism (VTE; RR 2.13; p = 0.004) and pulmonary embolism (RR 3.60; p = 0.001). The risk of hypertension, any-grade MACEs, and thromboembolic AEs was not significantly higher, apart from VTE (RR 2.17; p = 0.01).

Conclusions and clinical implications

There is higher risk of high-grade cardiovascular and thromboembolic toxicity with PARPi use in comparison to other treatments in mCRPC, although these toxicities are rare. Clinicians should be aware of this risk, especially in a population that often has comorbidities and concomitant treatments, for correct monitoring and management of these AEs.

Patient summary

Drugs called PARP inhibitors are very effective in the treatment of metastatic prostate cancer that does not respond to hormone treatment. However, their use is associated with some cardiovascular adverse events, although these are rare. Our study shows that these events seem to be more frequent with PARP inhibitors than with other treatments, especially for severe grades. Doctors and patients should be aware of this risk to help in preventing, recognizing, and managing the occurrence of these rare complications.

The Phase 3 KEYLYNK-006 Study of Pembrolizumab Plus Olaparib Versus Pembrolizumab Plus Pemetrexed as Maintenance Therapy for Metastatic Nonsquamous NSCLC

INTRODUCTION

Poly (adenosine diphosphate-ribose) inhibitors, including olaparib, upregulate programmed cell death ligand 1, which may increase the efficacy of anti-programmed cell death protein 1 and anti-programmed cell death ligand 1 therapies.

METHODS

In the phase 3 KEYLYNK-006 trial (NCT03976323), eligible adults with previously untreated metastatic nonsquamous NSCLC without targetable genetic alterations who had complete response, partial response, or stable disease after induction therapy with four cycles of pembrolizumab 200 mg every three weeks, pemetrexed 500 mg/m2, and carboplatin area under the concentration-time curve 5 mg/mL/min or cisplatin 75 mg/m2 were randomized in a one-to-one ratio to olaparib 300 mg orally twice daily or pemetrexed every three weeks, both given with up to 31 cycles of pembrolizumab every three weeks. Dual primary endpoints were progression-free survival (PFS) and overall survival (OS). Progression-free survival was tested at interim analysis 2 (i.e., final PFS analysis) and OS at final analysis (FA).

RESULTS

Of 1003 patients who received induction therapy, 672 (67.0%) were randomized to pembrolizumab plus olaparib (n = 337) or pembrolizumab plus pemetrexed (n = 335) in the intention-to-treat population. Median follow-up at FA was 39.9 (range: 28.1-51.5) months. At interim analysis 2, the median (95% confidence interval [CI]) PFS was 7.1 (5.6-8.7) months versus 8.3 (6.9-11.5) months in the olaparib versus pemetrexed groups (hazard ratio = 1.12, 95% CI: 0.92-1.36, p = 0.87). At FA, the median (95% CI) OS was 20.7 (18.0-24.8) months versus 23.0 (19.0-26.4) months (hazard ratio = 1.04, 95% CI: 0.87-1.25, p = 0.6649). Grade 3 to 5 maintenance treatment-related adverse events occurred in 26.1% versus 30.1% of patients, respectively.

CONCLUSION

Pembrolizumab plus maintenance olaparib did not improve PFS or OS versus pembrolizumab plus pemetrexed in previously untreated metastatic nonsquamous NSCLC without targetable genetic alterations.

Integrating BRCA testing into routine prostate cancer care: a multidisciplinary approach by SIUrO and other Italian Scientific Societies

Prostate cancer (PCa) ranks among the most prevalent malignancies in men, with notable associations to Hereditary Breast and Ovarian Cancer Syndrome (HBOC) and Lynch Syndrome, both linked to germline likely pathogenetic variant/pathogenetic variant (LPV/PV) in genes involved in DNA repair. Among these genes, BRCA2 in PCa patients is the most frequently altered. Despite progresses, challenges in BRCA carriers detection persist, with a quarter of PCa cases lacking family history.To address these challenges, a multidisciplinary expert panel from six Italian Scientific Societies, formulated a care pathway to integrate BRCA testing into routine clinical practice in different Italian geographical areas.The development process, promoted by the Italian Society of Uro-Oncology (SIUrO), involved three key stages. A preliminary meeting convened teams from different Italian regions to establish minimal requirements for a mini-counseling program (defined as a pre-test consultation carried out by clinicians responsible of patients' management) and propose care pathway models. At the same time, a comprehensive survey was launched to highlight regional variations in BRCA testing and identify eventual obstacles to testing activities. A subsequent meeting synthesized care pathway proposals and formulated a unified framework, acknowledging regional legislative variations as enriching factors. Lastly, implementation of the unified framework was promoted by the project faculty and identified regional team leaders.Survey results revealed significant regional disparities in BRCA testing, reimbursement policies, and access to genetic counseling. The proposed mini-counseling program outlined essential steps for patient identification, information provision, and multidisciplinary review, aiming to streamline BRCA testing processes.Expert recommendations emphasized offering tumor genetic testing to metastatic PCa patients eligible for PARP-i treatment and outlined criteria for genetic counseling and germline testing. Key considerations included family history and tumor characteristics.In conclusion, the proposed care pathway represents a critical step towards integrating BRCA testing into routine PCa care, aiming to optimize patient management and familial risk assessment within the constraints of the Italian healthcare system.

Heterogeneity of the Treatment Effect with PARP Inhibitors in Metastatic Castration-resistant Prostate Cancer: A Living Interactive Systematic Review and Meta-analysis

BACKGROUND AND OBJECTIVE

Selection of patients harboring mutations in homologous recombination repair (HRR) genes for treatment with a PARP inhibitor (PARPi) is challenging in metastatic castration-resistant prostate cancer (mCRPC). To gain further insight, we quantitatively assessed the differential efficacy of PARPi therapy among patients with mCRPC and different HRR gene mutations.

METHODS

This living meta-analysis (LMA) was conducted using the Living Interactive Evidence synthesis framework. We included clinical trials assessing PARPi as monotherapy in pretreated mCRPC or in combination with an androgen receptor pathway inhibitor (ARPI) in treatment-naïve patients. Random-effects meta-analyses were performed for a priori subgroups stratified by HRR status, BRCA status, and each gene.

KEY FINDINGS AND LIMITATIONS

This first report for our LMA includes 13 trials (4278 patients). Among patients with pretreated mCRPC receiving PARPi monotherapy, the tumor response rate per 100 person-months was numerically higher for patients with BRCA2 (50% prostate-specific antigen response [PSA50%] 3.3; objective response rate [ORR] 3.3), BRCA1 (PSA50% 1.2; ORR 2.0), or PALB2 (PSA50% 3.3; ORR 1.4) alterations than for patients with ATM (PSA50% 0.4; ORR 0.3), CDK12 (PSA50% 0.2; ORR 0.2), or CHEK2 (PSA50% 1.0; ORR 0.7) alterations. Among patients receiving PARPi + ARPI, a significant radiographic progression-free survival benefit was observed in those with BRCA (hazard ratio [HR] 0.28, 95% confidence interval [CI] 0.13-0.62) or CDK12 (HR 0.58, 95% CI 0.35-0.95) alterations, but not in patients with PALB2 (HR 0.53, 95% CI 0.21-1.32), ATM (HR 0.93, 95% CI 0.57-1.53), or CHEK2 (HR 0.92, 95% CI 0.53-1.61) alterations. An overall survival benefit was observed for patients with BRCA alterations (HR 0.47, 95% CI 0.31-0.71) after adjustment for crossover and subsequent therapy, but not for patients with PALB2 (HR 0.33, 95% CI 0.10-1.16), ATM (HR 0.97, 95% CI 0.57-1.67), CDK12 (HR 0.80, 95% CI 0.36-1.78), or CHEK2 (HR 0.81, 95% CI 0.37-1.75) alterations.

CONCLUSIONS AND CLINICAL IMPLICATIONS

Our LMA delivers information on the effect of PARPi therapy in relation to specific gene alterations in mCRPC via an interactive web platform. The evidence suggests the greatest PARPi benefit in patients with BRCA alterations, a strong signal of benefit in patients with PALB2 or CDK12 alterations, and no benefit in patients with ATM or CHEK2 alterations.

BRCA Mutation Testing in Men with Metastatic Castration-Resistant Prostate Cancer: Practical Guidance for Australian Clinical Practice

Some patients with metastatic castration-resistant prostate cancer (mCRPC) possess germline or acquired defects in the DNA damage repair (DDR) genes BRCA1 and BRCA2. Tumors with BRCA mutations exhibit sensitivity to poly-ADP ribose polymerase inhibitors (PARPi) such as olaparib and rucaparib. As a result, molecular diagnostic testing to identify patients with BRCA mutations eligible for the PARPi therapy has become an integral component of managing patients with mCRPC. There are practical challenges in the current molecular testing pathway in Australia that can compromise testing success. Testing success is often contingent on quality of tissue handling and laboratory processing techniques to minimize DNA degradation and suboptimal sequencing data quality. Greater adoption of best testing practices in Australia can be facilitated with education and greater awareness of expert recommendations. Here, we provide expert recommendations on how to optimize BRCA molecular diagnostic testing in patients with mCRPC. Optimization and standardization of molecular diagnostic testing will support health care providers and institutes in establishing more efficient testing pathways, enabling access to targeted therapies such as PARPi, and improving patient outcomes.

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.

PARP inhibitor-based treatment in metastatic, castration-resistant prostate cancer (mCRPC): A systematic review and meta-analysis

Background

We present a systematic review and meta-analysis of randomized clinical trials (RCTs) with PARPi either as monotherapy or in combination with an androgen receptor-targeted agent (ARTA) in first- and second-line settings.

Methods

Primary endpoints are radiographic progression free survival (rPFS) and overall survival (OS) in patients with mCRPC and either unselected, homologous recombination repair wild-type (HRR-), homologous recombination repair mutated (HRR+) or with BRCA1, BRCA2, or ATM mutation. The effect of PARPi + ARTA in the second-line setting is also explored. Safety is a secondary end-point.

Results

A total of five phase III (first line: MAGNITUDE, PROpel, TALAPRO-2; second line: PROfound, TRITON3) and two phase II RCTs (second line: NCT01972217, NCT01576172) were selected. In the first-line setting, rPFS was significantly improved in PARPi + ARTA arm in all comers (HR 0.70, p < 0.00001), HRR- (HR 0.76, p = 0.005), HRR+ (HR 0.57, p = 0.0003), and BRCA1/2-mutated patients (HR: 0.33, p < 0.00001). OS was improved in the population with HRR+ status (HR 0.76, p = 0.02) but not statistically significant in BRCA1/2-mutated patients (HR 0.57, 95% CI 0.30-1.08, p = 0.08). In the second line, PARPi improves rPFS (HR for BRCA2 0.31, p = 0.002) and OS (HR for BRCA1/2 0.71, p = 0.01) only in such patients. In this setting, no advantage was reported by adding a PARPi to an ARTA. The arm with PARPi either as monotherapy or in combination with ARTA showed a significantly higher toxicity profile.

Conclusions

PARPi-based therapy represents a compelling treatment option for HRR+ mCRPC, mainly BRCA1/2-mutated patients. However, further biomarker analysis are needed in order to identify other responsive patients across the different disease settings.

Novel astatine (211At)-labelled prostate-specific membrane antigen ligand with a neopentyl-glycol structure: evaluation of stability, efficacy, and safety using a prostate cancer xenograft model

PURPOSE

Prostate-specific membrane antigen (PSMA)-targeted alpha therapy is considered a promising alternative treatment for metastatic castration-resistant prostate cancer (mCRPC). Though astatine-211 (211At) is potentially useful alpha-emitter producible by cyclotrons, its clinical application has been limited by instability and a tendency to deastatination in vivo. To overcome these challenges, we developed [211At]At-NpG-PSMA, a novel PSMA ligand with a neopentyl-glycol structure that enhances in vivo stability against deastatination. This study aimed to evaluate the stability, anti-tumour effect, and safety of [211At]At-NpG-PSMA in mice.

METHODS

Xenograft models were prepared by subcutaneous transplantation of PSMA-positive PC-3 PIP cells into BALB/c nu/nu mice. [211At]At-NpG-PSMA was administered to assess biodistribution, and the anti-tumour effect was evaluated at doses of 0.32, 1.00 and 1.93 MBq in comparison with saline. Histopathological examinations were performed to evaluate damage to normal organs.

RESULTS

[211At]At-NpG-PSMA demonstrated high tumour uptake (42.0 ± 13.1%ID/g at 3 h) with minimal uptake in non-target tissues, including thyroid, stomach and salivary grands (0.28 ± 0.20%ID, 0.71 ± 0.12%ID/g and 0.88 ± 0.10%ID/g at 3 h, respectively). A dose-dependent anti-tumour effect was observed, with tumour volumes increasing by 796.0 ± 437.6% in the control versus 161.0 ± 213.4%, -76.4 ± 19.2% and - 59.5 ± 41.6% in the 0.32, 1.00 and 1.93 MBq groups, respectively, by day 15. Mild renal tubule regeneration was noted in the 1.00 MBq group.

CONCLUSION

[211At]At-NpG-PSMA demonstrated significant stability in vivo and anti-tumour effects with minimal side effects, indicating its potential as a new therapeutic drug for PSMA-targeted alpha therapy in mCRPC.

Olaparib: A Chemosensitizer for the Treatment of Glioblastoma

Glioblastoma (GBM) is the most prevalent and deadly primary brain tumor. The current treatment for GBM includes adjuvant chemotherapy with temozolomide (TMZ), radiation therapy, and surgical tumor excision. There is still an issue because 50% of patients with GBM who get TMZ have low survival rates due to TMZ resistance. The activation of several DNA repair mechanisms, such as Base Excision Repair (BER), DNA Mismatch Repair (MMR), and O-6- Methylguanine-DNA Methyltransferase (MGMT), is the main mechanism via which TMZ resistance develops. The zinc-finger DNA-binding enzyme poly (ADP-ribose) polymerase-1 (PARP1), which is activated by binding to DNA breaks, affects the activation of the MGMT, BER, and MMR pathway deficiency, which results in TMZ resistance in GBM. PARP inhibitors have been studied recently as sensitizing medications to increase TMZ potency. The first member of the PARP inhibitor family to be identified was Olaparib. It inhibits PARP1 and PARP2, which causes apoptosis in cancer cells and DNA strand break. Olaparib is currently investigated as a radio- and/or chemo-sensitizer in addition to being used as a single agent because it may increase the cytotoxic effects of other treatments. This review addresses Olaparib and its significance in treating TMZ resistance in GBM.

Management of individuals with heterozygous germline pathogenic variants in ATM: A clinical practice resource of the American College of Medical Genetics and Genomics (ACMG)

PURPOSE

ATM germline pathogenic variants (GPVs) are associated with a moderately increased risk of female breast cancer, pancreatic cancer, and prostate cancer. Resources for managing ATM heterozygotes in clinical practice are limited.

METHODS

An international workgroup developed a clinical practice resource to guide management of ATM heterozygotes using peer-reviewed publications and expert opinion.

RESULTS

Although ATM is a moderate (intermediate) penetrance gene, cancer risks may be considered as a continuous variable, influenced by family history and other modifiers. ATM GPV heterozygotes should generally be offered enhanced breast surveillance according to their personalized risk estimate and country-specific guidelines and, generally, risk-reducing mastectomy is not recommended. Prostate cancer surveillance should be considered. Pancreatic cancer surveillance should be considered based on assessment of family history, ideally as part of a clinical trial, with existence of country-specific guidelines. For ATM GPV heterozygotes who develop cancer, radiation therapy decisions should not be influenced by the genetic result. Although poly-adenosine diphosphate ribose polymerase inhibitors are licensed for use in metastatic castration-resistant prostate cancer and ATM GPVs, the evidence-base is currently weak.

CONCLUSION

Systematic prospective data collection is needed to establish the spectrum of ATM-associated cancer and determine the outlines of surveillance, response to cancer treatment, and survival.

Detection of Germline Variants in Patients With Localized and Metastatic Prostate Cancer Through Guideline-Based Testing

INTRODUCTION

There is increasing awareness that patients with prostate cancer frequently harbor germline variants that may carry important implications for them and their family members. Given the variable clinical guidelines, there remains a need to better understand which patients with prostate cancer are likely to harbor pathogenic or likely pathogenic (P/LP) germline variants. We sought to understand factors associated with P/LP germline variants in patients with metastatic or localized prostate cancer qualifying for National Comprehensive Cancer Network genetic testing criteria.

METHODS

Patients diagnosed with prostate cancer were offered genetic testing in accordance with National Comprehensive Cancer Network guidelines. Patient-level factors, including demographic, clinical, and pathologic data, were tracked in a prospectively collected registry. The association of the presence of a P/LP variant in germline testing results with patient-level factors was assessed using univariate and multivariate logistic regression. Variables were tested for overall significance with χ2 tests.

RESULTS

Five hundred five patients underwent germline testing and had clinical data available. Rates of P/LP germline variants were 7.6% (20/264) in patients with metastatic disease and 11.2% (27/241) in patients with localized disease. The most prevalent P/LP variants were CHEK2 (34%), BRCA2 (22%), ATM (10%), and HOXB13 (10%).

CONCLUSIONS

In this cohort of patients undergoing guideline-informed germline testing, P/LP germline variants were found in similar proportions across all age ranges and clinical characteristics. Only age at genetic testing for patients with metastatic disease was demonstrated to be predictive of the presence of a P/LP germline variant, highlighting the challenges associated with refining current clinical testing guidelines.

Bipolar androgen therapy for treatment of metastatic castration-resistant prostate cancer: A case series

INTRODUCTION

Advanced prostate cancer treatment has improved with androgen receptor signaling inhibitors (ARPI), yet many patients develop metastatic castration-resistant prostate cancer (mCRPC), characterized by sustained androgen receptor (AR) signaling. Bipolar androgen therapy (BAT) introduces supraphysiologic testosterone levels to inhibit tumor growth, offering novel treatment for mCRPC by exploiting AR-dependent mechanisms.

CASE PRESENTATIONS

Case 1: A 53-year-old man with mCRPC, post multiple systemic therapies, initiated BAT and pembrolizumab, achieving PSA reduction and improved quality of life before progression. The patient exhibited AR amplification, which may have contributed to favorable response to BAT. Case 2: A 73-year-old man with recurrent prostate cancer, stable on ADT and abiraterone, experienced PSA decline with BAT to an undetectable level, maintaining stability post-therapy discontinuation. Case 3: A 73-year-old man with metastatic prostate cancer, initially resistant to enzalutamide, achieved clinical benefit and disease control with BAT, although he did not meet PSA response criteria, patient had remarkable response upon enzalutamide rechallenge. Case 4: A 90-year-old man with localized prostate cancer, refractory to multiple treatments, experienced symptom relief and PSA reduction with BAT before progression.

CONCLUSION

BAT represents a promising treatment strategy for mCRPC. This case series underscores BAT's potential to induce significant clinical and biochemical responses, resensitize tumors to ARPIs, and improve patients' quality of life. Despite eventual progression in some cases, BAT offers a period of disease control. Further research is needed to optimize patient selection and understand the molecular determinants of BAT responsiveness.