Treatment Outcomes and Tumor Loss of Heterozygosity in Germline DNA Repair-deficient Prostate Cancer

Prognostic value of germline mutations in metastatic hormone-sensitive prostate cancer (mHSPC)

BACKGROUND

About 8% to 12% of patients presenting with mHSPC exhibit germline pathogenic variants (PV) in cancer predisposition genes. The aim of this study is to assess the presence of germline PV as a prognostic factor in the setting of mHSPC and to determine whether mutational status can predict rapid progression to castration resistance.

METHODS

Genetic analysis using a multigene next-generation sequencing (NGS) panel was performed on 34 patients diagnosed with mHSPC undergoing treatment. We assessed the prevalence of germline PV and examined differences based on clinical-pathological characteristics, family history (FH), prostate-specific antigen (PSA) response, impact on time to castration-resistant prostate cancer (TTCRPC), and overall survival (OS).

RESULTS

Germline PV were identified in 6 patients (17,6%). When comparing the clinical-pathological characteristics of PV carriers (n = 6) to noncarriers (n = 28), no significant associations were observed except for the presence of FH of hereditary breast and ovarian cancer (HBOC) syndrome and/or Lynch syndrome (P = 0.024). At a median follow-up of 33 months, significant differences in OS were observed based on the presence of PV (26 months in carriers vs. 74 months in noncarriers; P < 0.01). Patients who harbored a BRCA2 mutation (n = 3) showed a worse clinical outcome, presenting a shorter TTCRPC (7 months vs. 23 months; P = 0.005) and lower OS (7 months vs. 74 months; P < 0.001) compared to noncarriers (n = 31).

CONCLUSION

mHSPC germline PV carriers had a worse survival outcome. Furthermore, BRCA2 germline mutation was an independent poor prognostic factor for mHSPC disease, associated with earlier progression to castration-resistant prostate cancer, and shorter OS. These results highlight the importance of evaluating germline mutational status in patients with hormone-sensitive prostate cancer.

Novel insights into RB1 in prostate cancer lineage plasticity and drug resistance

Prostate cancer is the second most common malignancy among men in the world, posing a serious threat to men's health and lives. RB1 is the first human tumor suppressor gene to be described, and it is closely associated with the development, progression, and suppression of a variety of tumors. It was found that the loss of RB1 is an early event in prostate cancer development and is closely related to prostate cancer development, progression and treatment resistance. This paper reviews the current status of research on the relationship between RB1 and prostate cancer from three aspects: RB1 and prostate cell lineage plasticity; biological behavior; and therapeutic resistance. Providing a novel perspective for developing new therapeutic strategies for RB1-loss prostate cancer.

Impact of homologous recombination repair/BReast CAncer (BRCA) gene alterations on survival in a real-world setting of metastatic prostate cancer

OBJECTIVE

To investigate alterations of homologous recombination repair (HRR) and especially BReast CAncer 1/2 (BRCA1/2) gene on overall survival (OS). Moreover, to explore the effect of inhibition of poly(ADP-ribose)-polymerase (PARPi) as systemic therapy for metastatic castration-resistant prostate cancer (mCRPC).

PATIENTS AND METHODS

Of all HRR-screened patients with metastatic prostate cancer, baseline characteristics were sampled. Kaplan-Meier estimates and multivariable Cox regression models predicted the effect of HRR/BRCA1/2 alterations on OS.

RESULTS

Of 196 eligible patients, 61 (31%) harboured any HRR and 40 (20%) BRCA1/2 alterations. Of HRR alterations, 40 (66%) vs six (10%) vs five (8.2%) vs four (6.6%) vs two (3.3%) vs four (6.6%) were BRCA1/2 vs Ataxia-telangiectasia mutated kinase (ATM) vs checkpoint kinase 2 (CHEK2) vs cyclin-dependent kinase 12 (CDK12) vs Fanconi anaemia complementation Group A (FANCA) vs positive for other mutations. Of these, 30% received a PARPi. OS differed significantly between HRR-positive vs -negative patients. Specifically in hormone-sensitive prostate cancer, the median OS was 63 (HRR positive) vs 57 (BRCA1/2 positive) vs 113 months (HRR negative) (P ≤ 0.01). In mCRPC, OS was 42 (HRR positive) vs 41 (BRCA1/2 positive) vs 70 months (HRR negative) (P ≤ 0.01). HRR and BRCA1/2 alterations were associated with worse OS after multivariable adjustment. Finally, patients with mCRPC with BRCA1/2 mutation treated without PARPi harboured worse OS than patients with BRCA1/2 mutation and PARPi therapy (median OS: 33 vs 48 months, P < 0.03).

CONCLUSION

Incidence of HRR alteration in a clinical real-world setting is high when using blood- and tissue-based tests. Patients with HRR/BRCA alterations have worse outcomes resulting in significant OS differences between HRR/BRCA-positive patients with mCRPC with and without PARPi usage vs HRR/BRCA-negative patients.

TRIUMPH: phase II trial of rucaparib monotherapy in patients with metastatic hormone-sensitive prostate cancer harboring germline homologous recombination repair gene mutations

BACKGROUND

The activity of PARP inhibitors (PARPi) in patients with homologous recombination repair (HRR) mutations and metastatic castration-resistant prostate cancer has been established. We hypothesized that the benefit of PARPi can be maintained in the absence of androgen deprivation therapy (ADT) in an HRR-mutated population. We report the results of a phase II clinical trial of rucaparib monotherapy in patients with metastatic hormone-sensitive prostate cancer (mHSPC).

METHODS

This was a multi-center, single-arm phase II trial (NCT03413995) for patients with asymptomatic, mHSPC. Patients were required to have a pathogenic germline mutation in an HRR gene for eligibility. All patients received rucaparib 600 mg by mouth twice daily, without androgen deprivation. The primary endpoint was a confirmed PSA50 response rate.

RESULTS

Twelve patients were enrolled, 7 with a BRCA1/2 mutation and 5 with a CHEK2 mutation. The confirmed PSA50 response rate to rucaparib was 41.7% (N = 5/12, 95% CI: 15.2-72.3%, one-sided P = .81 against the 50% null), which did not meet the pre-specified efficacy boundary to enroll additional patients. In patients with measurable disease, the objective response rate was 60% (N = 3/5), all with a BRCA2 mutation. The median radiographic progression-free survival on rucaparib was estimated at 12.0 months (95% CI: 8.0-NR months). The majority of adverse events were grade ≤2, and expected.

CONCLUSION

Rucaparib can induce clinical responses in a biomarker-selected metastatic prostate cancer population without concurrent ADT. However, the pre-specified efficacy threshold was not met, and enrolment was truncated. Although durable responses were observed in a subset of patients, further study of PARPi treatment without ADT in mHSPC is unlikely to change clinical practice.

Advancing Prostate Cancer Care: Treatment Approaches to Precision Medicine, Biomarker Innovations, and Equitable Access

Genetic testing and molecular imaging have great promise in the accurate diagnosis and treatment of #prostate #cancer, but only if they can be developed and implemented to achieve equitable benefit for all men.

Therapeutic biomarkers in metastatic castration-resistant prostate cancer: does the state matter?

The treatment of metastatic castration-resistant prostate cancer (mCRPC) has been fundamentally transformed by our greater understanding of its complex biological mechanisms and its entrance into the era of precision oncology. A broad aim is to use the extreme heterogeneity of mCRPC by matching already approved or new targeted therapies to the correct tumor genotype. To achieve this, tumor DNA must be obtained, sequenced, and correctly interpreted, with individual aberrations explored for their druggability, taking into account the hierarchy of driving molecular pathways. Although tumor tissue sequencing is the gold standard, tumor tissue can be challenging to obtain, and a biopsy from one metastatic site or primary tumor may not provide an accurate representation of the current genetic underpinning. Sequencing of circulating tumor DNA (ctDNA) might catalyze precision oncology in mCRPC, as it enables real-time observation of genomic changes in tumors and allows for monitoring of treatment response and identification of resistance mechanisms. Moreover, ctDNA can be used to identify mutations that may not be detected in solitary metastatic lesions and can provide a more in-depth understanding of inter- and intra-tumor heterogeneity. Finally, ctDNA abundance can serve as a prognostic biomarker in patients with mCRPC.The androgen receptor (AR)-axis is a well-established therapeutical target for prostate cancer, and through ctDNA sequencing, insights have been obtained in (temporal) resistance mechanisms that develop through castration resistance. New third-generation AR-axis inhibitors are being developed to overcome some of these resistance mechanisms. The druggability of defects in the DNA damage repair machinery has impacted the treatment landscape of mCRPC in recent years. For patients with deleterious gene aberrations in genes linked to homologous recombination, particularly BRCA1 or BRCA2, PARP inhibitors have shown efficacy compared to the standard of care armamentarium, but platinum-based chemotherapy may be equally effective. A hierarchy exists in genes associated with homologous recombination, where, besides the canonical genes in this pathway, not every other gene aberration predicts the same likelihood of response. Moreover, evidence is emerging on cross-resistance between therapies such as PARP inhibitors, platinum-based chemotherapy and even radioligand therapy that target this genotype. Mismatch repair-deficient patients can experience a beneficial response to immune checkpoint inhibitors. Activation of other cellular signaling pathways such as PI3K, cell cycle, and MAPK have shown limited success with monotherapy, but there is potential in co-targeting these pathways with combination therapy, either already witnessed or anticipated. This review outlines precision medicine in mCRPC, zooming in on the role of ctDNA, to identify genomic biomarkers that may be used to tailor molecularly targeted therapies. The most common druggable pathways and outcomes of therapies matched to these pathways are discussed.

Treatment patterns and outcomes in metastatic castration-resistant prostate cancer patients with and without somatic or germline alterations in homologous recombination repair genes

BACKGROUND

Although germline BRCA mutations have been associated with adverse outcomes in prostate cancer (PC), understanding of the association between somatic/germline alterations in homologous recombination repair (HRR) genes and treatment outcomes in metastatic castration-resistant PC (mCRPC) is limited. The aim of this study was to investigate the prevalence and outcomes associated with somatic/germline HRR alterations, particularly BRCA1/2, in patients initiating first-line (1L) mCRPC treatment with androgen receptor signalling inhibitors (ARSi) or taxanes.

PATIENTS AND METHODS

Data from 729 mCRPC patients were pooled for CAPTURE from four multicentre observational studies. Eligibility required 1L treatment with ARSi or taxanes, adequate tumour samples and biomarker panel results. Patients underwent paired normal and tumour DNA analyses by next-generation sequencing using a custom gene panel including ATM, BRCA1, BRCA2, BRIP1, CDK12, CHEK2, FANCA, HDAC2, PALB2, RAD51B and RAD54L. Patients were divided into subgroups based on somatic/germline alteration(s): with BRCA1/2 mutations (BRCA); with HRR mutations except BRCA1/2 (HRR non-BRCA); and without HRR alterations (non-HRR). Patients without BRCA1/2 mutations were classified as non-BRCA. Radiographic progression-free survival (rPFS), progression-free survival 2 (PFS2) and overall survival (OS) were assessed.

RESULTS

Of 729 patients, 96 (13.2%), 127 (17.4%) and 506 (69.4%) were in the BRCA, HRR non-BRCA and non-HRR subgroups, respectively. BRCA patients performed significantly worse for all outcomes than non-HRR or non-BRCA patients (P < 0.05), while PFS2 and OS were significantly shorter for BRCA than HRR non-BRCA patients (P < 0.05). HRR non-BRCA patients also had significantly worse rPFS, PFS2 and OS than non-HRR patients. Exploratory analyses suggested that for BRCA patients, there were no significant differences in outcomes associated with 1L treatment choice (ARSi or taxanes) or with the somatic/germline origin of the alterations.

CONCLUSIONS

Worse outcomes were observed for mCRPC patients in the BRCA subgroup compared with non-BRCA subgroups, either HRR non-BRCA or non-HRR. Despite its heterogeneity, the HRR non-BRCA subgroup presented worse outcomes than the non-HRR subgroup. Screening early for HRR mutations, especially BRCA1/2, is crucial in improving mCRPC patient prognosis.

Evaluating first-line therapeutic strategies for metastatic castration-resistant prostate cancer: a comprehensive network meta-analysis and systematic review

Objective

This study aimed to evaluate the relative efficacy and safety of first-line treatment options for metastatic castration-resistant prostate cancer (mCRPC).

Methods

We systematically searched electronic databases, including PubMed and Web of Science, for studies published from their inception to April 3rd, 2023. Inclusion criteria were: 1) Completed Phase III or IV randomized controlled trials (RCTs) registered on ClinicalTrials.gov; 2) Patients with a confirmed diagnosis of mCRPC who had not previously received chemotherapy or novel endocrine therapies. We conducted a network meta-analysis using R software (version 3.4.0). Network graphs and risk of bias graphs were generated using Stata 14.0 and RevMan 5.4, respectively. The primary outcome was overall survival (OS), and the secondary outcome was the incidence of severe adverse events (SAEs).

Results

Seven RCTs encompassing 6,641 patients were included. The network meta-analysis revealed that both docetaxel+prednisone (DP) and cabazitaxel+prednisone (CP) significantly improved OS compared to abiraterone. Compared to placebo, DP showed comparable results to both cabazitaxel 20 mg/m^2+prednisone (C20P) and cabazitaxel 25 mg/m^2+prednisone (C25P) in terms of OS. For SAEs, both DP and C20P were superior to C25P, with no statistical difference between C20P and DP. The probability ranking plots indicated that C25P ranked highest for OS, while DP ranked highest for SAEs.

Conclusions

Based on our network meta-analysis, we recommend cabazitaxel 20 mg/m^2+prednisone (C20P) as the primary choice for first-line management of mCRPC, followed by DP. Enzalutamide and abiraterone are suggested as subsequent options. Radium-223 may be considered for patients presenting with bone metastases.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42023443943.

Prevalence of germline BRCA1/2 pathogenic variants in Japanese patients treated with castration-resistant prostate cancer and efficacy of CRPC treatment in real-world clinical practice

OBJECTIVE

The companion diagnosis for olaparib, a poly (ADP-ribose) polymerase inhibitor for prostate cancer, aims to detect BRCA1/2 gene variants. In clinical practice, the frequency of germline BRCA1/2 variants in patients receiving castration-resistant prostate cancer treatment is unknown. We aimed to evaluate the prevalence of germline BRCA1/2 variants and their relationship to prognosis and treatment efficacy in castration-resistant prostate cancer.

METHODS

Between June 2021 and 2023, 92 patients receiving castration-resistant prostate cancer treatment were examined for germline BRCA1/2 variants using BRACAnalysis CDx®. Furthermore, the associations between BRCA1/2 pathogenic variants and clinical outcomes were assessed.

RESULTS

Of the 92 patients referred for genetic testing, 6 (6.5%) carried germline pathogenic variants in BRCA1/2. The BRCA2 variant was the most frequent (n = 5), followed by BRCA1 variant (n = 1). Among the five variants in BRCA2, the p.Asp427Thrfs*3 variant was identified for the first time in prostate cancer. Overall survival from castration-resistant prostate cancer for patients with BRCA1/2 variants was significantly shorter than for patients without BRCA1/2 variants (P = 0.043). Progression-free survival of androgen receptor signaling inhibitors for patients with BRCA1/2 variants was significantly shorter than for those without (P = 0.003). Progression-free survival of taxane chemotherapy was significantly shorter in patients with BRCA1/2 variants than in those without (P = 0.0149).

CONCLUSIONS

In clinical practice, 6.5% of patients treated with castration-resistant prostate cancer carried germline BRCA1/2 pathogenic variants. Japanese castration-resistant prostate cancer patients with germline BRCA1/2 mutants have a poor prognosis and may be less responsive to treatment with androgen receptor signaling inhibitors and taxane-based chemotherapy for castration-resistant prostate cancer.

Inherited Mutations in DNA Damage Repair Genes in Italian Men with Metastatic Prostate Cancer: Results from the Meet-URO 10 Study

Background

The prevalence of pathogenic germline mutations in DNA damage repair (gDDR) genes in the Italian population is unknown.

Objective

In this prospective multicenter cohort study, we evaluated the prevalence of gDDR alterations in the Italian population affected by metastatic prostate cancer (mPCa) and analyzed the impact on response to therapy, survival, and time to castration resistance.

Design setting and participants

In an observational prospective trial, 300 consecutive Italian mPCa patients, enrolled in the Meet-Uro-10 trial from three academic Italian centers, were recruited between 2017 and 2019 and were screened for gDDR mutations in 107 genes.

Outcome measurements and statistical analysis

The primary endpoint was to assess the prevalence of gDDR mutations in the Italian population of patients with mPCa. The secondary endpoints included the association of gDDR subgroups with metastatic onset, Gleason score, and time to castration resistance.

Results and limitations

We identified 297 valuable patients. Forty-six patients had a pathogenic/likely pathogenic variant (15.5%, 95% confidence interval: 11.4-19.6): the more frequent was gBRCA2 found in nine cases (3%), followed by gATM in five cases (1.7%). In patients without mutations, longer median overall survival was observed with the sequence docetaxel-androgen receptor signaling inhibitor (ARSI) than with the sequence ARSI-docetaxel (87.9 vs 42 mo, p = 0.0001). In a univariate analysis, the median time to castration resistance in gDDR mutated patients was 19.8 mo, versus 23.7 mo in no mutated patients (p = 0.024). There were no associations of gDDR subgroups with metastatic onset and Gleason score ≥8. In our cohort, variants of unknown significance in gDDR genes were found in 80 patients and might have a prognostic relevance.

Conclusions

The study reported the prevalence of gDDR in the Italian population. The presence of gBRCA2 mutations correlates with a shorter time to the onset of castration resistance disease.

Patient summary

The prevalence of gBRCA2 in the Italian population is 3%, which is similar to that in the Spanish population, identifying similarities between people of the Western Mediterranean area.

Feasibility of Next-generation Sequencing of Liquid Biopsy (Circulating Tumor DNA) Samples and Tumor Tissue from Patients with Metastatic Prostate Cancer in a Real-world Clinical Setting in Germany

BACKGROUND AND OBJECTIVE

With European Medicines Agency approval of PARP inhibitors in metastatic castration-resistant prostate cancer and ongoing trials in metastatic hormone-sensitive prostate cancer, detection of genetic alterations in BRCA1/2 and other homologous recombination repair genes has gained an important role. Our aim was to investigate the feasibility and comparability of comprehensive next-generation sequencing (NGS) of liquid biopsy (LB; circulating tumor DNA) and tumor tissue (TT) samples in a real-world clinical setting.

METHODS

The study cohort consisted of 50 patients with metastatic prostate cancer (mPC) who had TT NGS performed for BRCA1/2 alterations and consent for additional LB NGS. The Oncomine Comprehensive Assay v3 (Thermo Fisher Scientific, Waltham, MA, USA) was used for TT NGS. The Guardant360 83-gene assay (Guardant Health, Palo Alto, CA, USA) was used for LB NGS, including all types of somatic alterations, microsatellite instability, and blood tumor mutational burden. We calculated BRCA1/2 alteration rates and the negative percentage agreement (NPA) and positive percentage agreement (PPA) between TT and LB results.

KEY FINDINGS AND LIMITATIONS

TT NGS was successful in 44/50 patients (88%), with pathogenic BRCA1/2 alterations detected in four (9%). LB NGS was successful in all 50 patients (100%), with BRCA1/2 alterations detected in ten (20%). In a subgroup analysis for the 44 patients with successful TT NGS, NPA was 85% and PPA was 50%. The median time between TT sample collection and blood sampling for NGS was 132 wk (IQR 94-186). The limited sample size and differences in the time of NGS assessment are limitations.

CONCLUSIONS AND CLINICAL IMPLICATIONS

LB NGS resulted in a higher detection rate for BRCA1/2 alterations in comparison to conventional TT NGS (20% vs 9%). Ideally, BRCA1/2 testing should be based on both approaches to identify all patients with mPC eligible for PARP inhibitor therapy.

PATIENT SUMMARY

Our study shows that genetic tests for both tumor tissue and blood samples results in higher rates of detection of BRCA1/2 gene alterations in patients with metastatic prostate cancer.

Development of PARP inhibitors in advanced prostate cancer

The relatively high prevalence of alterations in the homologous recombination repair (HRR) pathway described in advanced prostate cancer provides a unique opportunity to develop therapeutic strategies that take advantage of the decreased tumor ability to repair DNA damage. Poly ADP-ribose polymerase (PARP) inhibitors have been demonstrated to improve the outcomes of metastatic castration-resistant prostate cancer (mCRPC) patients with HRR defects, particularly in those with BRCA1/2 alterations. To expand the benefit of PARPi to patients without detectable HRR alterations, multiple studies are addressing potential synergies between PARP inhibition (PARPi) and androgen receptor pathway inhibitors (ARSi), radiation, radioligand therapy, chemotherapy, or immunotherapy, and these strategies are also being evaluated in the hormone-sensitive setting. In this review, we summarize the development of PARPi in prostate cancer, the potential synergies, and combinations being investigated as well as the future directions of PARPi for the management of the disease.

Synthetic Lethality by Co-Inhibition of Androgen Receptor and Polyadenosine Diphosphate-Ribose in Metastatic Prostate Cancer

Androgen receptor pathway inhibitors (ARPI) and polyadenosine diphosphate-ribose inhibitors (PARPi) are part of the standard of care in patients with metastatic castration-resistant prostate cancer (mCRPC). There is biological evidence that the association of ARPI and PARPi could have a synergistic effect; therefore, several ongoing clinical trials are investigating the efficacy of this combination with preliminary results that are not perfectly concordant in identifying patients who can obtain the most benefit from this therapeutic option. The purpose of this review is to describe the PARPi mechanisms of action and to analyze the biological mechanisms behind the interplay between the androgen receptor and the PARPi system to better understand the rationale of the ARPI + PARPi combinations. Furthermore, we will summarize the preliminary results of the ongoing studies on these combinations, trying to understand in which patients to apply. Finally, we will discuss the clinical implications of this combination and its possible future perspectives.

Therapeutic sensitivity to standard treatments in BRCA positive metastatic castration-resistant prostate cancer patients-a systematic review and meta-analysis

BACKGROUND

Recent oncology guidelines recommend BRCA1/2 testing for a wide range of prostate cancer (PCa) patients. In addition, PARP inhibitors are available for mutation-positive metastatic castration-resistant PCa (mCRPC) patients following prior treatment with abiraterone, enzalutamide or docetaxel. However, the question of which of these standard treatments is the most effective for BRCA1/2 positive mCRPC patients remains to be answered. The aim of this meta-analysis was to assess the efficacy of abiraterone, enzalutamide and docetaxel in BRCA1/2 mutation-positive mCRPC patients in terms of PSA-response (PSA50), progression-free survival (PFS) and overall survival (OS).

METHODS

As no interventional trials are available on this topic, we performed the data synthesis of BRCA1/2 positive mCRPC patients by using both proportional and individual patient data. For PSA50 evaluation, we pooled event rates with 95% confidence intervals (CI), while for time-to-event (PFS, OS) analyses we used individual patient data with random effect Cox regression calculations.

RESULTS

Our meta-analysis included 16 eligible studies with 348 BRCA1/2 positive mCRPC patients. In the first treatment line, response rates for abiraterone, enzalutamide and docetaxel were 52% (CI: 25-79%), 64% (CI: 43-80%) and 55% (CI: 36-73%), respectively. Analyses of individual patient data revealed a PFS (HR: 0.47, CI: 0.26-0.83, p = 0.010) but no OS (HR: 1.41, CI: 0.82-2.42, p = 0.210) benefit for enzalutamide compared to abiraterone-treated patients.

CONCLUSIONS

Our PSA50 analyses revealed that all the three first-line treatments have therapeutic effect in BRCA1/2 positive mCRPC; although, based on the results of PSA50 and PFS analyses, BRCA positive mCRPC patients might better respond to enzalutamide treatment. However, molecular marker-driven interventional studies directly comparing these agents are crucial for providing higher-level evidence.

Impact of germline DNA repair gene variants on prognosis and treatment of men with advanced prostate cancer

The clinical importance of germline variants in DNA repair genes (DRGs) is becoming increasingly recognized, but their impact on advanced prostate cancer prognosis remains unclear. A cohort of 221 newly diagnosed metastatic castration-resistant prostate cancer (mCRPC) patients were screened for pathogenic germline variants in 114 DRGs. The primary endpoint was progression-free survival (PFS) on first-line androgen signaling inhibitor (ARSI) treatment for mCRPC. Secondary endpoints were time to mCRPC progression on initial androgen deprivation therapy (ADT) and overall survival (OS). Twenty-seven patients (12.2%) carried a germline DRG variant. DRG carrier status was independently associated with shorter PFS on first-line ARSI [HR 1.72 (1.06-2.81), P = 0.029]. At initiation of ADT, DRG carrier status was independently associated with shorter progression time to mCRPC [HR 1.56, (1.02-2.39), P = 0.04] and shorter OS [HR 1.99, (1.12-3.52), P = 0.02]. Investigating the contributions of individual germline DRG variants on PFS and OS revealed CHEK2 variants to have little effect. Furthermore, prior taxane treatment was associated with worse PFS on first-line ARSI for DRG carriers excluding CHEK2 (P = 0.0001), but not for noncarriers. In conclusion, germline DRG carrier status holds independent prognostic value for predicting advanced prostate cancer patient outcomes and may potentially inform on optimal treatment sequencing already at the hormone-sensitive stage.

BRCA-deficient metastatic prostate cancer has an adverse prognosis and distinct genomic phenotype

BACKGROUND

Genomic alterations in DNA damage response (DDR) genes are common in metastatic castration-resistant prostate cancer (mCRPC). Understanding how these genomic events impact prognosis and/or treatment response is vital for optimising clinical outcomes.

METHODS

Targeted sequencing was performed on 407 plasma samples from 375 men with mCRPC. Using the CLIA-certified PredicineCARE™ cell-free DNA (cfDNA) assay, pathogenic alterations in 152 key genes (including 27 DDR-related genes) were assessed, as was the presence and mechanisms of biallelic loss in BRCA2.

FINDINGS

At least one DDR alteration was present in 34.5% (129/375) of patients (including monoallelic alterations). The most frequently altered DDR genes were BRCA2 (19%), ATM (13%), FANCA (5%), CHEK2 (5%) and BRCA1 (3%). Patients with BRCA alterations, especially BRCA2, had significantly worse progression-free survival (PFS) (Hazard ratio (HR) 3.3 [95% CI 1.9-6.0]; Cox regression p < 0.001), overall survival (HR 2.2 [95% CI 1.1-4.5]; Cox regression p = 0.02) and PSA response rates to androgen receptor (AR) pathway inhibitors (32% vs 60%, chi-square p = 0.02). BRCA-deficient tumours were also enriched for alterations within multiple genes including in the AR and PI3K pathways. Zygosity of BRCA2 alterations had no discernible impact on clinical outcomes, with similarly poor PFS for monoallelic vs biallelic loss (median 3.9 months vs 3.4 months vs copy neutral 9.8 months).

INTERPRETATION

These data emphasise that the BRCA genes, in particular BRCA2, are key prognostic biomarkers in mCRPC. The clinical utility of BRCA2 as a marker of poor outcomes may, at least in cfDNA assays, be independent of the zygosity state detected. Enrichment of actionable genomic alterations in cfDNA from BRCA-deficient mCRPC may support rational co-targeting strategies in future clinical trials.

FUNDING

Several funding sources have supported this study. A full list is provided in the Acknowledgments. No funding was received from Predicine, Inc. during the conduct of the study.

Is It Time to Anticipate the Use of PARP Inhibition in Prostate Cancer Patients?

The increasing diffusion of genetic analysis regarding the pathogenetic variants (PVs) of genes involved in DNA Damage Repair (DDR) mechanisms and the development of Poly ADP ribose polymerase (PARP) inhibitors (PARPis) led to the first valid precision medicine option tailored toward metastatic prostate cancer (mPC). The concept of anticipation in the systemic treatment of mPC was initially adopted for androgen receptor signaling inhibitors (ARSIs) to describe the expansion of their indications, from the setting of the late-stage second-line treatment of metastatic castration-resistant prostate cancer (mCRPC) to first-line therapy in selected cases. There is already mounting evidence in favor of the anticipation of PARPis in the first line of mCRPC therapy, and further evidence in favor of mHSPC is emerging. Many studies have demonstrated the synergism between ARSIs and PARP inhibitors. Recent discoveries regarding the crosstalk between the androgen receptor (AR) and DNA repair mechanisms are disconnecting the use of PARPis from genetic analysis. The new message emerging is that the combination of PARPis with ARSIs may work independently of DDR mutational status. As a matter of fact, most of the recent trials analyzing the combination of PARPis with abiraterone or enzalutamide as a first-line therapy enrolled mCRPC patients irrespective of their mutational status. The PROPEL trial concluded that the advantage of the combination was independent of PV status, despite a higher advantage being reported in the BRCA1/2 mutated subgroup. The MAGNITUDE trial, however, showed a significant advantage only in the DDR mutated subgroup, and the DDR non-mutated cohort was closed for further enrollment. The combination of PARPis with ARSIs represents a significant strategy with a view to the anticipation and intensification of care in mPC. However, it should not nullify the advantages of precision medicine linked to the genetic analysis of DDR genes.

Performance of clinical risk scores and prediction models to identify pathogenic germline variants in patients with advanced prostate cancer

PURPOSE

Determining the frequency and distribution of pathogenic germline variants (PGVs) in Austrian prostate cancer (PCa) patients and to assess the accuracy of different clinical risk scores to correctly predict PGVs.

METHODS

This cross-sectional study included 313 men with advanced PCa. A comprehensive personal and family history was obtained based on predefined questionnaires. Germline DNA sequencing was performed between 2019 and 2021 irrespective of family history, metastatic or castration status or age at diagnosis. Clinical risk scores for hereditary cancer syndromes were evaluated and a PCa-specific score was developed to assess the presence of PGVs.

RESULTS

PGV presence was associated with metastasis (p = 0.047) and castration resistance (p = 0.011), but not with personal cancer history or with relatives with any type of cancer. Clinical risk scores (Manchester score, PREMM5 score, Amsterdam II criteria or Johns Hopkins criteria) showed low sensitivities (3.3-20%) for assessing the probability of PGV presence. A score specifically designed for PCa patients stratifying patients into low- or high-risk regarding PGV probability, correctly classified all PGV carriers as high-risk, whereas a third of PCa patients without PGVs was classified as low risk of the presence of PGVs.

CONCLUSION

Application of common clinical risk scores based on family history are not suitable to identify PCa patients with high PGV probabilities. A PCa-specific score stratified PCa patients into low- or high-risk of PGV presence with sufficient accuracy, and germline DNA sequencing may be omitted in patients with a low score. Further studies are needed to evaluate the score.

Impact of DNA damage repair alterations on prostate cancer progression and metastasis

Prostate cancer is among the most common diseases worldwide. Despite recent progress with treatments, patients with advanced prostate cancer have poor outcomes and there is a high unmet need in this population. Understanding molecular determinants underlying prostate cancer and the aggressive phenotype of disease can help with design of better clinical trials and improve treatments for these patients. One of the pathways often altered in advanced prostate cancer is DNA damage response (DDR), including alterations in BRCA1/2 and other homologous recombination repair (HRR) genes. Alterations in the DDR pathway are particularly prevalent in metastatic prostate cancer. In this review, we summarise the prevalence of DDR alterations in primary and advanced prostate cancer and discuss the impact of alterations in the DDR pathway on aggressive disease phenotype, prognosis and the association of germline pathogenic alterations in DDR genes with risk of developing prostate cancer.

Niraparib and Abiraterone Acetate for Metastatic Castration-Resistant Prostate Cancer

PURPOSE

Metastatic castration-resistant prostate cancer (mCRPC) remains a lethal disease with current standard-of-care therapies. Homologous recombination repair (HRR) gene alterations, including BRCA1/2 alterations, can sensitize cancer cells to poly (ADP-ribose) polymerase inhibition, which may improve outcomes in treatment-naïve mCRPC when combined with androgen receptor signaling inhibition.

METHODS

MAGNITUDE (ClinicalTrials.gov identifier: NCT03748641) is a phase III, randomized, double-blinded study that evaluates niraparib and abiraterone acetate plus prednisone (niraparib + AAP) in patients with (HRR+, n = 423) or without (HRR-, n = 247) HRR-associated gene alterations, as prospectively determined by tissue/plasma-based assays. Patients were assigned 1:1 to receive niraparib + AAP or placebo + AAP. The primary end point, radiographic progression-free survival (rPFS) assessed by central review, was evaluated first in the BRCA1/2 subgroup and then in the full HRR+ cohort, with secondary end points analyzed for the full HRR+ cohort if rPFS was statistically significant. A futility analysis was preplanned in the HRR- cohort.

RESULTS

Median rPFS in the BRCA1/2 subgroup was significantly longer in the niraparib + AAP group compared with the placebo + AAP group (16.6 v 10.9 months; hazard ratio [HR], 0.53; 95% CI, 0.36 to 0.79; P = .001). In the overall HRR+ cohort, rPFS was significantly longer in the niraparib + AAP group compared with the placebo + AAP group (16.5 v 13.7 months; HR, 0.73; 95% CI, 0.56 to 0.96; P = .022). These findings were supported by improvement in the secondary end points of time to symptomatic progression and time to initiation of cytotoxic chemotherapy. In the HRR- cohort, futility was declared per the prespecified criteria. Treatment with niraparib + AAP was tolerable, with anemia and hypertension as the most reported grade ≥ 3 adverse events.

CONCLUSION

Combination treatment with niraparib + AAP significantly lengthened rPFS in patients with HRR+ mCRPC compared with standard-of-care AAP.

[Media: see text].

Genetic and Genomic Testing for Prostate Cancer: Beyond DNA Repair

Significant progress has been made in genetic and genomic testing for prostate cancer across the disease spectrum. Molecular profiling is increasingly relevant for routine clinical management, fueled in part by advancements in testing technology and integration of biomarkers into clinical trials. In metastatic prostate cancer, defects in DNA damage response genes are now established predictors of benefit to US Food and Drug Administration-approved poly (ADP-ribose) polymerase inhibitors and immune checkpoint inhibitors, and trials are actively investigating these and other targeted treatment strategies in earlier disease states. Excitingly, opportunities for molecularly informed management beyond DNA damage response genes are also maturing. Germline genetic variants (eg, BRCA2 or MSH2/6) and polygenic germline risk scores are being investigated to inform cancer screening and active surveillance in at-risk carriers. RNA expression tests have recently gained traction in localized prostate cancer, enabling patient risk stratification and tailored treatment intensification via radiotherapy and/or androgen deprivation therapy for localized or salvage treatment. Finally, emerging minimally invasive circulating tumor DNA technology promises to enhance biomarker testing in advanced disease pending additional methodological and clinical validation. Collectively, genetic and genomic tests are rapidly becoming indispensable tools for informing the optimal clinical management of prostate cancer.

Urinary DNA as a Tool for Germline and Somatic Mutation Detection in Castration-Resistant Prostate Cancer Patients

(1) Background: DNA damage response (DDR) pathway gene mutations are detectable in a significant number of patients with metastatic castration-resistant prostate cancer (mCRPC). The study aimed at identification of germline and/or somatic DDR mutations in blood and urine samples from patients with mCRPC for correlation with responses to entire sequence of systemic treatment and survival outcomes. (2) Methods: DDR gene mutations were assessed prospectively in DNA samples from leukocytes and urine sediments from 149 mCRPC patients using five-gene panel targeted sequencing. The impact of DDR status on progression-free survival, as well as treatment-specific and overall survival, was evaluated using Kaplan–Meier curves and Cox regression. (3) Results: DDR mutations were detected in 16.6% of urine and 15.4% of blood samples. BRCA1, BRCA2, CHEK2, ATM and NBN mutations were associated with significantly shorter PFS in response to conventional androgen deprivation therapy and first-line mCRPC therapy with abiraterone acetate. Additionally, BRCA1 and BRCA2 mutation-bearing patients had a significantly worse response to radium-223. However, DDR mutation status was predictive for the favourable effect of second-line abiraterone acetate after previous taxane-based chemotherapy. (4) Conclusions: Our data confirm the benefit of non-invasive urine-based genetic testing for timely identification of high-risk prostate cancer cases for treatment personalization.

Impact of concurrent tumor events on the prostate cancer outcomes of germline BRCA2 mutation carriers

BACKGROUND

Several studies have reported the association of germline BRCA2 (gBRCA2) mutations with poor clinical outcomes in prostate cancer (PCa), but the impact of concurrent somatic events on gBRCA2 carriers survival and disease progression is unknown.

PATIENTS AND METHODS

To ascertain the role of frequent somatic genomic alterations and histology subtypes in the outcomes of gBRCA2 mutation carriers and non-carriers, we correlated the tumour characteristics and clinical outcomes of 73 gBRCA2 and 127 non-carriers. Fluorescent in-situ hybridisation and next-generation sequencing were used to detect copy number variations in BRCA2, RB1, MYC and PTEN. Presence of intraductal and cribriform subtypes was also assessed. The independent impact of these events on cause-specific survival (CSS), metastasis-free survival and time to castration-resistant disease was assessed using cox-regression models.

RESULTS

Somatic BRCA2-RB1 co-deletion (41% versus 12%, p < 0.001) and MYC amplification (53.4% versus 18.8%, p < 0.001) were enriched in gBRCA2 compared to sporadic tumours. Median CSS from diagnosis of PCa was 9.1 versus 17.6 years in gBRCA2 carriers and non-carriers, respectively (HR 2.12; p = 0.002), Median CSS in gBRCA2 carriers increased to 11.3 and 13.4 years in the absence of BRCA2-RB1 deletion or MYC amplification, respectively. Median CSS of non-carriers decreased to 8 and 2.6 years if BRCA2-RB1 deletion or MYC amplification were detected.

CONCLUSIONS

gBRCA2-related prostate tumours are enriched for aggressive genomic features, such as BRCA2-RB1 co-deletion and MYC amplification. The presence or absence of these events modify the outcomes of gBRCA2 carriers.

The prevalence of gene mutations in homologous recombination repair pathways in Japanese patients with metastatic castration-resistant prostate cancer in real-world clinical practice: The multi-institutional observational ZENSHIN study

BACKGROUND

Metastatic castration-resistant prostate cancer (mCRPC) is a genetically heterogeneous disease with a poor prognosis. The prevalence of mutations in homologous recombination repair (HRR) pathway genes, including BRCA1/2, as well as treatment patterns and clinical outcomes, are not well characterized among Japanese men with mCRPC.

METHODS

This multicenter, noninterventional cohort study enrolled Japanese men with mCRPC from 24 institutions between 2014 and 2018. Mutations in the 15 HRR-related genes were assessed using archival primary or metastatic tumor samples. Patterns of sequential therapies for mCRPC were investigated. Patients were followed up for survival evaluation including prostate-specific antigen progression-free survival (PSA-PFS) and overall survival (OS).

RESULTS

Of the 143 patients analyzed, HRR-related mutations were detected in 51 patients (35.7%). The most frequently mutated genes were CDK12 (N = 19, 13.3%), followed by BRCA2 (N = 18, 12.6%), ATM (N = 8, 5.6%), and CHEK2 (N = 3, 2.1%). The most common type of first-line therapy for mCRPC was next-generation hormonal agents (NHA, 44.4%), followed by first-generation antiandrogens (FGA, 30.3%), and taxanes (22.5%). Commonly prescribed first-/second-line sequential regimens included FGA/NHA (17.6%), NHA/NHA (15.5%), and NHA/taxanes (14.1%). The median PSA-PFS and OS for the entire cohort were 5.6 and 26.1 months, respectively. Patients carrying BRCA1/2 mutations had numerically shorter PSA-PFS (median 3.3 vs. 5.9 months) and OS (median 20.7 vs. 27.3 months) than those without mutations.

CONCLUSIONS

In conclusion, approximately one-third of Japanese patients with mCRPC carried mutations in HRR-related genes in this study. The real-world outcomes of mCRPC are poor with conventional therapy, warranting an expansion of treatment options based on genetic abnormalities of the disease.

Prognostic value of genomic mutations in metastatic prostate cancer

Metastatic prostate cancer (mPC) has a poor prognosis, and new treatment strategies are currently being offered for patients in clinical practice, but mPC is still incurable. A considerable proportion of patients with mPC harbor homologous recombination repair (HRR) mutations, which may be more sensitive to poly (ADP-ribose) polymerase inhibitors (PARPis). We retrospectively included genomic and clinical data from 147 patients with mPC from a single clinical center, with a total of 102 circulating tumor DNA (ctDNA) samples and 60 tissue samples. The frequency of genomic mutations was analyzed and compared with that in Western cohorts. Cox analysis was used to assess progression-free survival (PFS) and prognostic factors related to prostate-specific antigen (PSA) after standard systemic therapy for mPC. The most frequently mutated gene in the HRR pathway was CDK12 (18.3%), followed by ATM (13.7%) and BRCA2 (13.0%). The remaining common ones were TP53 (31.3%), PTEN (12.2%), and PIK3CA (11.5%). The frequency of BRCA2 mutation was close to that of the SU2C-PCF cohort (13.3%), but the frequency of CDK12, ATM, and PIK3CA mutations was significantly higher than that in the SU2C-PCF cohort: 4.7%, 7.3%, and 5.3%, respectively. CDK12 mutation were less responsive to androgen receptor signaling inhibitors (ARSIs), docetaxel, and PARPi. BRCA2 mutation helps predict PARPi efficacy. Additionally, androgen receptor (AR)-amplified patients do not respond well to ARSIs, and PTEN mutation are associated with poorer docetaxel response. These findings support the genetic profiling of patients with mPC after diagnosis to guide treatment stratification to customize personalized treatment.

Exploring new frontiers in prostate cancer research: Report from the 2022 Coffey-Holden prostate cancer academy meeting

INTRODUCTION

The 2022 Coffey-Holden Prostate Cancer Academy (CHPCA) Meeting, "Exploring New Frontiers in Prostate Cancer Research," was held from June 23 to 26, 2022, at the University of California, Los Angeles, Luskin Conference Center, in Los Angeles, CA.

METHODS

The CHPCA Meeting is an annual discussion-oriented scientific conference organized by the Prostate Cancer Foundation, that focuses on emerging and next-step topics deemed critical for making the next major advances in prostate cancer research and clinical care. The 2022 CHPCA Meeting included 35 talks over 10 sessions and was attended by 73 academic investigators.

RESULTS

Major topic areas discussed at the meeting included: prostate cancer diversity and disparities, the impact of social determinants on research and patient outcomes, leveraging real-world and retrospective data, development of artificial intelligence biomarkers, androgen receptor (AR) signaling biology and new strategies for targeting AR, features of homologous recombination deficient prostate cancer, and future directions in immunotherapy and nuclear theranostics.

DISCUSSION

This article summarizes the scientific presentations from the 2022 CHPCA Meeting, with the goal that dissemination of this knowledge will contribute to furthering global prostate cancer research efforts.

Analysis of BRCA2 Copy Number Loss and Genomic Instability in Circulating Tumor Cells from Patients with Metastatic Castration-resistant Prostate Cancer

BACKGROUND

BRCA2 alterations predict for a response to poly-ADP-ribose polymerase inhibition in metastatic castration-resistant prostate cancer (mCRPC). However, detection is hindered by insufficient tumor tissue and low sensitivity of cell-free DNA for detecting copy number loss.

OBJECTIVE

To evaluate the BRCA2 loss detection using single-cell, shallow whole-genome sequencing (sWGS) of circulating tumor cells (CTCs) in patients with mCRPC.

DESIGN, SETTING, AND PARTICIPANTS

We analyzed CTC samples collected concurrently with tumor biopsies intended for clinical sequencing in patients with progressing mCRPC.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Differences in proportions were evaluated using the chi-square test. Correlations between assays were analyzed in linear regression models. Associations between alterations and genomic instability were assessed on the single-cell level using mixed-effect negative binomial models.

RESULTS AND LIMITATIONS

We identified 138 patients with concurrent CTC and biopsy samples. CTC sWGS generated copy number profiles in a similar proportion of patients to biopsy samples (83% vs 78%, p = 0.23), but was more effective than bone biopsies (79% vs 50%; p = 0.009). CTC sWGS detected BRCA2 loss in more patients than tissue at the ≥1 (42% vs 16%; p < 0.001) and ≥2 (27% vs 16%; p = 0.028) CTC thresholds. The overall prevalence of BRCA2 loss was not increased in CTCs using sample-level composite z scores (p = 0.4), but was significantly increased compared with a lower-than-expected prevalence in bone samples (21% vs 3%, p = 0.014). Positive/negative predictive values for CTC BRCA2 loss were 89%/96% using the ≥1 CTC threshold and 67%/92% using the composite z score. CTC BRCA2 loss was associated with higher genomic instability in univariate (1.4-fold large-scale transition difference, 95% confidence interval [CI]: 1.2-1.6; p < 0.001) and multivariable analysis (1.4-fold difference, 95% CI: 1.2-1.6; p < 0.001).

CONCLUSIONS

Copy number profiles can reliably be generated using CTC sWGS, which detected a majority of tissue-confirmed BRCA2 loss and "CTC-only" losses. BRCA2 losses were supported by increases in genomic instability.

PATIENT SUMMARY

Current testing strategies have limitations in their ability to detect BRCA2 loss, a relatively common alteration in prostate cancer that is used to identify patients who may benefit from targeted therapy. In this paper, we evaluated whether we could detect BRCA2 loss in individual tumor cells isolated from patient blood samples and found this method to be suitable for further analysis.

Differential responses to taxanes and PARP inhibitors in ATM- versus BRCA2-mutated metastatic castrate-resistant prostate cancer

BACKGROUND

PARP (poly(ADP-ribose) polymerase) inhibitors (PARPi) are now standard of care in metastatic castrate-resistant prostate cancer (mCRPC) patients with select mutations in DNA damage repair (DDR) pathways, but patients with ATM- and BRCA2 mutations may respond differently to PARPi. We hypothesized that differences may also exist in response to taxanes, which may inform treatment sequencing decisions.

METHODS

mCRPC patients (N = 158) with deleterious ATM or BRCA2 mutations who received taxanes, PARPi, or both were retrospectively identified from 11 US academic centers. Demographic, treatment, and survival data were collected. Kaplan-Meier analyses were performed and Cox hazard ratios (HR) were calculated for progression-free survival (PFS) as well as overall survival (OS), from time of first taxane or PARPi therapy.

RESULTS

Fifty-eight patients with ATM mutations and 100 with BRCA2 mutations were identified. Fourty-four (76%) patients with ATM mutations received taxane only or taxane before PARPi, while 14 (24%) received PARPi only or PARPi before taxane. Patients with ATM mutations had longer PFS when taxane was given first versus PARPi given first (HR: 0.74 [95% confidence interval [CI]: 0.37-1.50]; p = 0.40). Similarly, OS was longer in patients with ATM mutations who received taxane first (HR: 0.56 [CI: 0.20-1.54]; p = 0.26). Among patients with BRCA2 mutations, 51 (51%) received taxane first and 49 (49%) received PARPi first. In contrast, patients with BRCA2 mutations had longer PFS when PARPi was given first versus taxane given first (HR: 0.85 [CI: 0.54-1.35]; p = 0.49). Similarly, OS was longer in patients with BRCA2 mutations who received PARPi first (HR: 0.75 [CI: 0.41-1.37]; p = 0.35).

CONCLUSIONS

Our retrospective data suggest differential response between ATM and BRCA2 mutated prostate cancers in terms of response to PARPi and to taxane chemotherapy. When considering the sequence of PARPi versus taxane chemotherapy for mCRPC with DDR mutations, ATM, and BRCA2 mutation status may be helpful in guiding choice of initial therapy.

Estimating copy number to determine BRCA2 deletion status and to expect prognosis in localized prostate cancer

BACKGROUND

The significance of BRCA alterations has been implicated in the development of metastatic castration-resistant prostate cancer (PC). The details of the frequency and significance of BRCA alterations in localized PC remain unknown. In this study, we investigated the frequency and clinical significance of BRCA alterations in localized PCs using an in-house next-generation sequencer (NGS) system.

METHODS

DNA was extracted from formalin-fixed paraffin-embedded tissues of surgical specimens from 126 patients with clinically localized PC who underwent radical prostatectomy. The mutation information of 164 cancer genes was analyzed using the PleSSision-Rapid test. Both copy number (CN) variation and loss of heterozygosity of various genes, such as BRCA1 and BRCA2, were estimated and reported.

RESULTS

Next-generation sequencer analyses revealed that the BRCA2 CN was decreased in 17 patients (13.5%) and the BRCA1 CN in six (4.8%) patients. NGS-based CN values were shown to be highly correlated with droplet digital PCR-based CN values. Tissue-specific BRCA expression investigated using the Human Protein Atlas showed that the decreased CN of BRCA2, but not BRCA1, is responsible for the decreased BRCA activity in PC. Ten of the 22 patients with decreased BRCA2 CN were presumed to have somatic heterozygous deletion. There were no observed associations between the heterozygous deletion of BRCA2 and various clinicopathological parameters. Furthermore, three of 10 patients developed biochemical recurrence within 3 months after surgery. Multivariate analyses revealed that the initial prostate-specific antigen levels and BRCA2 CN were independent factors for biochemical recurrence.

CONCLUSION

Our results suggest that a decrease in BRCA2 CN may be used as a biomarker for predicting recurrence after surgery in localized PC. Early screening for somatic alterations in BRCA2 using NGS may help to broadly predict the risk of PC progression.

How the Analysis of the Pathogenetic Variants of DDR Genes Will Change the Management of Prostate Cancer Patients

Herein, we analyze answers achieved, open questions, and future perspectives regarding the analysis of the pathogenetic variants (PV) of DNA damage response (and repair) (DDR) genes in prostate cancer (PC) patients. The incidence of PVs in homologous recombination repair (HRR) genes among men with metastatic PC varied between 11% and 33%, which was significantly higher than that in non-metastatic PC, and BRCA2 mutations were more frequent when compared to other DDR genes. The determination of the somatic or germline PVs of BRCA2 was able to define a tailored therapy using PARP inhibitors in metastatic castration-resistant prostate cancer (mCRPC) progression after first-line therapy, with significant improvements in the radiologic progression-free survival (rPFS) and overall survival (OS) rates. We propose testing all metastatic PC patients for somatic and germline HRR mutations. Somatic determination on the primary site or on historic paraffin preparations with a temporal distance of no longer than 5 years should be preferred over metastatic site biopsies. The prognostic use of DDR PVs will also be used in selected high-risk cases with non-metastatic stages to better arrange controls and therapeutic primary options. We anticipate that the use of poly-ADP-ribose polymerase (PARP) inhibitors in hormone-sensitive prostate cancer (HSPC) and in combination with androgen receptor signaling inhibitors (ARSI) will be new strategies.

The Prognostic Significance of Homologous Recombination Repair Pathway Alterations in Metastatic Hormone Sensitive Prostate Cancer

INTRODUCTION

The homologous recombination repair (HRR) pathway is a frequently mutated pathway in advanced prostate cancer. The clinical course of patients with HRR gene alterations who have metastatic hormone sensitive prostate cancer (mHSPC) has not been fully characterized. Here, we examine the outcomes of men with mHSPC with HRR alterations.

METHODS

We conducted a single-center retrospective analysis of men with mHSPC who underwent next generation sequencing. The primary objective was to assess the time from diagnosis of mHSPC to metastatic castrate resistance prostate cancer (mCRPC) in patients with pathogenic HRR alterations compared to individuals lacking these alterations. Key secondary objectives included time to mCRPC in prespecified cohorts, PSA response, and overall survival.

RESULTS

151 men with mHSPC were identified for the study. 24% (N = 37) had pathogenic HRR gene alterations detected with the most common alterations found in BRCA2 (n = 15), ATM (n = 10), and CDK12 (n = 7). Time to mCRPC was significantly decreased in patients with HRR gene alterations versus those without such alterations (12.7 vs. 16.1 months, HR 1.95, P = .02). In multivariate analysis, the effect of HRR gene alterations on time to CRPC remained significant when adjusting for age, mHSPC therapy, the volume of disease, the presence of visceral metastases, and PSA (adjusted HR 1.69, P = .02). Stratified by specific HRR gene alteration, patients with BRCA2 or CDK12 had significantly decreased time to mCRPC compared to other HRR alterations.

CONCLUSION

HRR gene alterations are associated with the worse outcomes in mHSPC with significantly shorter time to mCRPC. Given the established role of Poly (ADP-ribose) Polymerase (PARP) inhibitors in mCRPC, these data highlight an opportunity to examine PARP inhibitors earlier in the clinical course for prostate cancer patients. Ongoing prospective studies will further validate the role of PARP inhibitors in mHSPC patients.

Germline Variants in DNA Damage Repair Genes and HOXB13 Among Black Patients With Early-Onset Prostate Cancer

PURPOSE

Genetic studies of prostate cancer susceptibility have predominantly focused on non-Hispanic White men, despite the observation that Black men are more likely to develop prostate cancer and die from the disease. Therefore, we sought to identify genetic variants in Black patients diagnosed with early-onset prostate cancer.

METHODS

Whole-exome sequencing of germline DNA from a population-based cohort of Black men diagnosed with prostate cancer at age 62 years or younger was performed. Analysis was focused on a panel of DNA damage repair (DDR) genes and HOXB13. All discovered variants were ranked according to their pathogenic potential based upon REVEL score, evidence from existing literature, and prevalence in the cohort. Logistic regression was used to investigate associations between mutation status and relevant clinical characteristics.

RESULTS

Among 743 Black prostate cancer patients, we identified 26 unique pathogenic (P) or likely pathogenic (LP) variants in 14 genes (including HOXB13, BRCA1/2, BRIP1, ATM, CHEK2, and PALB2) among 30 men, or approximately 4.0% of the patient population. We also identified 33 unique variants of unknown significance in 16 genes among 39 men. Because of the rarity of these variants in the population, most associations between clinical characteristics did not achieve statistical significance. However, our results suggest that carriers for P or LP (P/LP) variants were more likely to have a first-degree relative diagnosed with DDR gene-associated cancer, have a higher prostate-specific antigen at time of diagnosis, and be diagnosed with metastatic disease.

CONCLUSION

Variants in DDR genes and HOXB13 may be important cancer risk factors for Black men diagnosed with early-onset prostate cancer, and are more frequently observed in men with a family history of cancer.

Impact of family history on clinicopathological variables and disease progression in Japanese prostate cancer patients undergoing robotic-assisted radical prostatectomy

OBJECTIVE

We evaluated whether a first-degree family history (FH) of prostate cancer (PCa) in Japanese patients undergoing robotic-assisted radical prostatectomy (RP) is correlated with clinicopathological variables and disease progression.

METHODS

We reviewed consecutive 392 localized PCa patients undergoing robotic-assisted RP at our institution between 2015 and 2020. Information on FH was obtained via a self-administered questionnaire. A positive FH was defined as having a first-degree FH: a father and/or one or more brothers with PCa prior to diagnosis. All patients had clinically localized PCa treated by robotic-assisted RP. We evaluated the relationship between clinical characteristics, pathological findings, and biochemical progression-free survival (bPFS) according to first-degree FH status.

RESULTS

Median follow-up was 20.8 months. FH was identified in 42 (10.7%) patients. Patients in the FH group (median, 64.8 years) were diagnosed at a significantly younger age than patients in the non-FH (NFH) group (patients without FH) (median, 67.7 years) (p = 0.003). The 5-year bPFS in the FH and NFH groups was 72.0% and 78.1%, respectively (p = 0.90). A subgroup analysis revealed a significant difference in prostate-specific antigen (PSA) density between the FH group (median, 0.51 ng/ml/cm³ ) and the NFH group (median, 0.29 ng/ml/cm³ ) in patients younger than 60 years (p = 0.033).

CONCLUSIONS

In this RP population, FH of PCa was not associated with worse clinical characteristics, pathological findings, or disease progression. Patients with a FH underwent surgery at a significantly younger age, and among patients <60 years, patients with a FH had significantly higher PSA density compared with patients without a FH.

Prognostic significance of pathogenic variants in BRCA1, BRCA2, ATM and PALB2 genes in men undergoing hormonal therapy for advanced prostate cancer

BACKGROUND

The prognostic significance of germline variants in homologous recombination repair genes in advanced prostate cancer (PCa), especially with regard to hormonal therapy, remains controversial.

METHODS

Germline DNA from 549 Japanese men with metastatic and/or castration-resistant PCa was sequenced for 27 cancer-predisposing genes. The associations between pathogenic variants and clinical outcomes were examined. Further, for comparison, DNA from prostate biopsy tissue samples from 80 independent patients with metastatic PCa were analysed.

RESULTS

Forty-four (8%) patients carried germline pathogenic variants in one of the analysed genes. BRCA2 was most frequently altered (n = 19), followed by HOXB13 (n = 9), PALB2 (n = 5) and ATM (n = 5). Further, the BRCA1, BRCA2, PALB2 and ATM variants showed significant association with a short time to castration resistance and overall survival (hazard ratio = 1.99 and 2.36; 95% CI, 1.15-3.44 and 1.23-4.51, respectively), independent of other clinical variables. Based on log-rank tests, the time to castration resistance was also significantly short in patients with BRCA1, BRCA2, PALB2 or ATM somatic mutations and TP53 mutations.

CONCLUSIONS

Germline variants in BRCA1, BRCA2, PALB2 or ATM are independent prognostic factors of the short duration of response to hormonal therapy in advanced PCa.

Prognostic Role of DNA Damage Response Genes Mutations and their Association With the Sensitivity of Olaparib in Prostate Cancer Patients

Objective

Evidence shows that gene mutation is a significant proportion of genetic factors associated with prostate cancer. The DNA damage response (DDR) is a signal cascade network that aims to maintain genomic integrity in cells. This comprehensive study was performed to determine the link between different DNA damage response gene mutations and prostate cancer.

Materials and methods

A systematic literature search was performed using PubMed, Web of Science, and Embase. Papers published up to February 1, 2022 were retrieved. The DDR gene mutations associated with prostate cancer were identified by referring to relevant research and review articles. Data of prostate cancer patients from multiple PCa cohorts were obtained from cBioPortal. The OR or HR and 95% CIs were calculated using both fixed-effects models (FEMs) and random-effects models (REMs).

Results

Seventy-four studies were included in this research, and the frequency of 13 DDR genes was examined. Through the analysis of 33 articles that focused on the risk estimates of DDR genes between normal people and PCa patients, DDR genes were found to be more common in prostate cancer patients (OR = 3.6293 95% CI [2.4992; 5.2705]). Also, patients in the mutated group had a worse OS and DFS outcome than those in the unmutated group (P < .05). Of the 13 DDR genes, the frequency of 9 DDR genes in prostate cancer was less than 1%, and despite differences in race, BRCA2 was the potential gene with the highest frequency (REM Frequency = .0400, 95% CI .0324 - .0541). The findings suggest that mutations in genes such as ATR, BLM, and MLH1 in PCa patients may increase the sensitivity of Olaparib, a PARP inhibitor.

Conclusion

These results demonstrate that mutation in any DDR pathway results in a poor prognosis for PCa patients. Furthermore, mutations in ATR, BLM, and MLH1 or the expression of POLR2L, PMS1, FANCE, and other genes significantly influence Olaparib sensitivity, which may be underlying therapeutic targets in the future.

Two cases of CRPC with BRCA mutation treated by olaparib after favorable response to cisplatin

Introduction

Several prostate cancers carry homologous recombination repair mutations that respond to olaparib. Because of the mechanism, the efficacy of platinum-based therapy can be used to predict the efficacy of poly(adenosine diphosphate-ribose) polymerase inhibitors such as olaparib.

Case presentation

We experienced two neuroendocrine prostate cancer patients who achieved a response duration of more than 1 year with platinum-based therapy. Case 1 had a BRCA2 mutation in the germline and case 2 had a BRCA2 mutation in a somatic chromosome only. Both patients responded well to olaparib.

Conclusion

Cisplatin and olaparib may overlap in response due to their medicinal action. It may be useful to consider genetic testing in some CRPC patients who have responded to cisplatin.

PARP Inhibitors in Advanced Prostate Cancer in Tumors with DNA Damage Signatures

Simple Summary

This review paper seeks to summarize the current literature on the role of PARP Inhibitors in Advanced Prostate Cancer in tumors with defects in genes associated with DNA damage repair. It will give particular attention to the role of PARPi in tumors with non-BRCA DNA damage repair genes. The aim of this review is to summarize the literature on PARPi and their activity treating BRCA and non BRCA tumors with DNA damage signatures.

Abstract

Since 2010, significant progress has been made in the treatment of metastatic castrate resistant prostate cancer (mCRPC). While these advancements have improved survival, mCRPC remains a lethal disease, with a precision medicine framework that is lagging behind compared to other cancers. Poly (ADP-ribose) polymerase (PARP) inhibitor (PARPi) studies in prostate cancer (PCa) have focused primarily on the homologous recombination repair (HRR) genes, specifically BRCA1 and BRCA2. While homologous recombination deficiency (HRD) can be prompted by germline or somatic BRCA1/2 genetic mutations, it can also exist in tumors with intact BRCA1/BRCA2 genes. While the sensitivity of PARPi in tumors with non-BRCA DNA damage signatures is not as well established, it has been suggested that genomic alterations in DNA damage repair (DDR) genes other than BRCA may confer synthetic lethality with PARPI in mCRPC. The aim of this review is to summarize the literature on PARPi and their activity treating BRCA and non BRCA tumors with DNA damage signatures.

Whole-exome sequencing reveals a comprehensive germline mutation landscape and identifies twelve novel predisposition genes in Chinese prostate cancer patients

Prostate cancer is the most inheritable cancer with approximately 42% of disease risk attributed to inherited factors by studies of twins, indicating the importance of additional genetic screening to identify predisposition variants. However, only DNA damage repair (DDR) genes have been investigated thoroughly in prostate cancer. To determine the comprehensive germline mutation landscape in Chinese prostate cancer patients, we performed whole exome sequencing in 100 Han Chinese patients with prostate cancer in Hong Kong and identified deleterious germline mutations. A total of 36 deleterious germline variants in 25 genes were identified in 29% patients. Variants were found in eight pathways, including DNA methylation, DDR, and tyrosine-protein kinase. These findings were validated in an independent Chinese cohort of 167 patients with prostate cancer in Shanghai. Seven common deleterious-variant-containing genes were found in discovery cohort (7/25, 28%) and validation cohort (7/28, 25%) with three genes not described before (LDLR, MYH7 and SUGCT) and four genes previously reported (FANCI, ITGA6, PABPC1 and RAD54B). When comparing with that of a cohort of East Asian healthy individuals, 12 non-DDR novel potential predisposition genes (ADGRG1, CHD4, DNMT3A, ERBB3, GRHL1, HMBS, LDLR, MYH7, MYO6, NT5C2, NUP98 and SUGCT) were identified using the discovery and validation cohorts, which have not been previously reported in prostate cancer patients in all ethnic groups. Taken together, this study reveals a comprehensive germline mutation landscape in Chinese prostate cancer patients and discovers 12 novel non-DDR predisposition genes to lay the groundwork for the optimization of genetic screening.

Prostate cancer is the most inheritable cancer with about 42% of disease risk attributed to inherited factors, indicating the importance of additional genetic screening to identify predisposition variants. However, only DNA damage repair (DDR) genes have been studied thoroughly in prostate cancer. To determine the comprehensive germline mutation landscape in Chinese prostate cancer patients, we performed whole exome sequencing in 100 Han Chinese patients with prostate cancer in Hong Kong and identified deleterious germline mutations. A total of 36 deleterious germline variants in 25 genes were identified in 29% patients. Variants were found in eight pathways, including DNA methylation, DDR, and tyrosine-protein kinase. These findings were validated in an independent Chinese cohort of 167 patients with prostate cancer in Shanghai. Seven common deleterious-variant-containing genes were found in discovery cohort and validation cohort with three genes not described before (LDLR, MYH7 and SUGCT) and four genes previously reported. When comparing with that of a cohort of East Asian healthy individuals, 12 non-DDR novel potential predisposition genes were identified using the discovery and validation cohorts, which have not been previously reported in prostate cancer patients in all ethnic groups.

Overcoming Obstacles in Liquid Biopsy Developments for Prostate Cancer

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

DNA damage repair gene germline profiling for metastatic prostate cancer patients of different ancestries

BACKGROUND

Germline and somatic mutations in DNA damage repair genes (DDRg) are now recognized as new biomarkers for the management of metastatic prostate cancers (mPC). We evaluate the frequency of germline DDRg mutations among French mPC patients of European and African ancestries.

METHODS

Targeted next-generation sequencing of 21 DDRg was performed on germline DNA from 557 mPC patients, including 15.1% of cases with an African origin.

RESULTS

Forty-seven germline mutations in 11 DDR genes were identified in 46 patients of the total cohort (8.3%). BRCA2 (4.1%) and ATM (2.0%) were the most frequently mutated genes. There was no difference in DDRg mutation frequency between mPC patients of European ancestry and those of African origin. Germline mutations of BRCA2 were associated with a positive family history of breast cancer (p = 0.02). The mean age at metastatic stage (59.7 vs. 67.0; p = 0.0003) and the mean age at death (65.2 vs. 73.9; p = 0.0003) were significantly earlier for carriers of BRCA2 mutation than for non-carriers. Moreover, the Cox model showed that BRCA2 positive status was statistically associated with poorer survival (hazard ratio: 0.29; 95% confidence interval 0.18-0.48; p < 0.0001).

CONCLUSION

We showed that, in France, BRCA2 and ATM are the main predisposing DDR genes in mPC patients, with a particular aggressiveness for BRCA2 leading to early metastatic stage and death.

Germline genetics of prostate cancer

BACKGROUND

An important fraction (>/~10%) of men with high-risk, localized prostate cancer and metastatic prostate cancer carry germline (heritable) pathogenic and likely pathogenic variants (also known as mutations) in DNA repair genes. These can represent known or suspected autosomal dominant cancer predisposition syndromes. Growing evidence suggests that pathogenic variants in key genes involved in homologous recombination and mismatch DNA repair are important in prostate cancer initiation and/or the development of metastases.

AIMS

Here we provide a comprehensive review regarding individual genes and available literature regarding risks for developing prostate cancer, and discuss current national guidelines for germline genetic testing in the prostate cancer population and treatment implications.

RESULTS

The association with prostate cancer risk and treatment implications is best understood for those with germline mutations of BRCA2, with emerging data supporting associations with ATM, CHEK2, BRCA1, HOXB13, MSH2, MSH6, PALB2, TP53 and NBN. Treatment implications in the metastatic castration resistant prostate cancer setting include rucaparib and olaparib, and pembrolizumab with potential clinical trial opportunities in earlier disease settings.

DISCUSSION

The data summarized in this review has led to the expansion of national guidelines for germline genetic testing in prostate cancer. We review these guidelines, and discuss the importance of cascade genetic testing of relatives, diverse populations with attention to inclusion, as well as prostate cancer screening updates and clinical trial opportunities for men who carry genetic risk factors for prostate cancer.

PARP Inhibition, a New Therapeutic Avenue in Patients with Prostate Cancer

Up to 25% of patients with metastatic prostate cancer present with germline or somatic DNA damage repair alterations, some of which are associated with aggressive disease and poor outcomes. New data have brought poly(ADP-ribose) polymerase (PARP) inhibitors into sharp focus in the treatment of metastatic castrate-resistant prostate cancer (mCRPC). Olaparib improved survival after at least one new hormonal therapy (NHT) in a cohort of patients harboring BRCA1, BRCA2 or ATM mutations in the PROfound trial, while rucaparib, talazoparib and niraparib demonstrated compelling activity in phase II trials. While patients with prostate cancer and BRCA1 or BRCA2 mutations may derive greatest benefit of PARP inhibition, the magnitude of benefit seems much lower in the context of most other homologous recombination gene mutations. Several PARP inhibitors are currently developed in combination with conventional therapy, including chemotherapy, NHT, and alpha-particle emitters, at different disease stages. Herein, we review the rationale for PARP inhibition in patients with prostate cancer, discuss the impact of PARP inhibitors on outcomes, and explore underlying challenges for future developments.

Implications of DNA damage repair alterations for the management of prostate cancer

PURPOSE OF REVIEW

In this review, we summarize the prevalence of alterations in DNA damage repair (DDR) genes in prostate cancer, their clinical significance, the therapeutic strategies developed to take advantage of the impaired tumour ability to repair DNA and the diagnostic approaches available to identify patients likely to benefit from DDR-targeting agents.

RECENT FINDINGS

DDR alterations are more frequent in metastatic than in localized prostate cancer and some of them associate with aggressive disease whereas the significance of others remain unclear. The most appropriate management approach for DDR-defective prostate cancer patients is unknown. Clinical trials have demonstrated the efficacy of different poly-ADP ribose polymerase inhibitors (PARPi) to treat metastatic castration-resistant prostate cancer patients with BRCA1/2 alterations, although there may be other DDR alterations that sensitize patients to these drugs. Multiple strategies to target DDR defects are being investigated, including PARPi in combination, platinum-based chemotherapy and immunotherapy, both in earlier and late disease stages. Optimization of molecular testing is paramount for the implementation of precision oncology in prostate cancer.

SUMMARY

Certain DDR defects present in prostate cancer have prognostic and therapeutic implications whereas the significance of other DDR alterations is yet to be elucidated.

Outcomes of Patients with Metastatic Castration-Resistant Prostate Cancer According to Somatic Damage DNA Repair Gene Alterations

(1) Background: In literature, approximately 20% of mCRPC present somatic DNA damage repair (DDR) gene mutations, and their relationship with response to standard therapies in mCRPC is not well understood. The objective was to evaluate outcomes of mCRPC patients treated with standard therapies according to somatic DDR status. (2) Methods: Eighty-three patients were recruited at Caen Cancer Center (France). Progression-free survival (PFS) after first-line treatment was analyzed according to somatic DDR mutation as primary endpoint. PFS according to first exposure to taxane chemotherapy and PFS2 (time to second event of disease progression) depending on therapeutic sequences were also analyzed. (3) Results: Median first-line PFS was 9.7 months in 33 mutated patients and 8.4 months in 50 non-mutated patients (p = 0.9). PFS of first exposure to taxanes was 8.1 months in mutated patients and 5.7 months in non-mutated patients (p = 0.32) and significantly longer among patients with ATM/BRCA1/BRCA2 mutations compared to the others (10.6 months vs. 5.5 months, p = 0.04). PFS2 was 16.5 months in mutated patients, whatever the sequence, and 11.7 months in non-mutated patients (p = 0.07). The mutated patients treated with chemotherapy followed by NHT had a long median PFS2 (49.8 months). (4) Conclusions: mCRPC patients with BRCA1/2 and ATM benefit from standard therapies, with a long response to taxanes.

Implementation of a prostate cancer-specific targeted sequencing panel for credentialing of patient-derived cell lines and genomic characterization of patient samples

BACKGROUND

Primary and metastatic prostate cancers have low mutation rates and recurrent alterations in a small set of genes, enabling targeted sequencing of prostate cancer-associated genes as an efficient approach to characterizing patient samples (compared to whole-exome and whole-genome sequencing). For example, targeted sequencing provides a flexible, rapid, and cost-effective method for genomic assessment of patient-derived cell lines to evaluate fidelity to initial patient tumor samples.

METHODS

We developed a prostate cancer-specific targeted next-generation sequencing (NGS) panel to detect alterations in 62 prostate cancer-associated genes as well as recurring gene fusions with ETS family members, representing the majority of common alterations in prostate cancer. We tested this panel on primary prostate cancer tissues and blood biopsies from patients with metastatic prostate cancer. We generated patient-derived cell lines from primary prostate cancers using conditional reprogramming methods and applied targeted sequencing to evaluate the fidelity of these cell lines to the original patient tumors.

RESULTS

The prostate cancer-specific panel identified biologically and clinically relevant alterations, including point mutations in driver oncogenes and ETS family fusion genes, in tumor tissues from 29 radical prostatectomy samples. The targeted panel also identified genomic alterations in cell-free DNA and circulating tumor cells (CTCs) from patients with metastatic prostate cancer, and in standard prostate cancer cell lines. We used the targeted panel to sequence our set of patient-derived cell lines; however, no prostate cancer-specific mutations were identified in the tumor-derived cell lines, suggesting preferential outgrowth of normal prostate epithelial cells.

CONCLUSIONS

We evaluated a prostate cancer-specific targeted NGS panel to detect common and clinically relevant alterations (including ETS family gene fusions) in prostate cancer. The panel detected driver mutations in a diverse set of clinical samples of prostate cancer, including fresh-frozen tumors, cell-free DNA, CTCs, and cell lines. Targeted sequencing of patient-derived cell lines highlights the challenge of deriving cell lines from primary prostate cancers and the importance of genomic characterization to credential candidate cell lines. Our study supports that a prostate cancer-specific targeted sequencing panel provides an efficient, clinically feasible approach to identify genetic alterations across a spectrum of prostate cancer samples and cell lines.

Past, Current, and Future Strategies to Target ERG Fusion-Positive Prostate Cancer

Simple Summary

In addition to its role in development and in the vascular and hematopoietic systems, ERG plays a central role in prostate cancer. Approximately 40–50% of prostate cancer cases are characterized by ERG gene fusions, which lead to ERG overexpression. Importantly, inhibition of ERG activity in prostate cancer cells decreases their viability. Therefore, inhibiting ERG might represent an important step to improve treatment efficacy for patients with ERG-positive prostate tumors. Here, we summarize the attempts made over the past years to repress ERG activity, the current use of ERG fusion detection and the strategies that might be utilized in the future to treat ERG fusion-positive tumors.

Abstract

The ETS family member ERG is a transcription factor with physiological roles during development and in the vascular and hematopoietic systems. ERG oncogenic activity characterizes several malignancies, including Ewing’s sarcoma, leukemia and prostate cancer (PCa). In PCa, ERG rearrangements with androgen-regulated genes—mostly TMPRSS2—characterize a large subset of patients across disease progression and result in androgen receptor (AR)-mediated overexpression of ERG in the prostate cells. Importantly, PCa cells overexpressing ERG are dependent on ERG activity for survival, further highlighting its therapeutic potential. Here, we review the current understanding of the role of ERG and its partners in PCa. We discuss the strategies developed in recent years to inhibit ERG activity, the current therapeutic utility of ERG fusion detection in PCa patients, and the possible future approaches to target ERG fusion-positive tumors.

Clinical Management of Prostate Cancer in High-Risk Genetic Mutation Carriers

Simple Summary

Men with certain genetic differences are at much higher risks of developing metastatic and lethal prostate cancer. With the recent introduction of a new class of medications specifically targeted to these gene repair pathways (PARP inhibitors), it is critical to review the state of the literature surrounding the management of men with prostate cancer who have these genetic differences. We review the existing literature to address common clinical questions pertaining to this population. There is an urgent need for further research regarding clinical management in these scenarios as patients are increasingly seeking out genetic testing and consulting healthcare professionals for guidance.

Abstract

Background: Prostate cancer is a leading cause of death. Approximately one in eight men who are diagnosed with prostate cancer will die of it. Since there is a large difference in mortality between low- and high-risk prostate cancers, it is critical to identify individuals who are at high-risk for disease progression and death. Germline genetic differences are increasingly recognized as contributing to risk of lethal prostate cancer. The objective of this paper is to review prostate cancer management options for men with high-risk germline mutations. Methods: We performed a review of the literature to identify articles regarding management of prostate cancer in individuals with high-risk germline genetic mutations. Results: We identified numerous publications regarding the management of prostate cancer among high-risk germline carriers, but the overall quality of the evidence is low. Conclusions: We performed a review of the literature and compiled clinical considerations for the management of individuals with high-risk germline mutations when they develop prostate cancer. The quality of the evidence is low, and there is an immediate need for further research and the development of consensus guidelines to guide clinical practice for these individuals.

Clinical Significance of Gene Mutations and Polymorphic Variants and their Association with Prostate Cancer Risk in Polish Men

Objectives: We tested the association of germline variants in BRCA1, BRCA2, CHEK2, CDKN2A, CYP1B1, HOXB13, MLH1, NBS1, NOD2 andPALB2 genes, as well as in 8q24 region, with prostate cancer (PC) risk and estimated their impact on disease clinical course, including overall survival time in Polish men with localized PC qualified for radical treatment.Materials and Methods: DNA of 110 patients with localized prostate cancer treated with radical prostatectomy (RP), from each age group and with different stages of the disease. DNA samples of the control group consisted of 111 men, volunteers, without PC (age-matched to study group). Sanger sequencing, AS-PCR, RFLP-PCR, and multiplex-PCR were used for  variants detection.Results: The percentage of men with ≥1 germline variant was higher in PC group (52.7%) than in healthy men (37.8%) (P = .03). The presence of ≥2 variants was associated with shorter survival than the presence of one or no variant in the PC group (P = .14, trend). The HOXB13 G84E was detected in 2.9% of PC men and in no healthy men (P = .19, trend, OR = 7.21). A CHEK2 truncating mutation (1100delC or IVS2+1G>A) was detected in 2/110 (1.8%) PC patients and in no healthy men (P = .29, OR=5.14). The NBS1 I171V was detected in 2/110 (1.8%) PC patients and in no men from the control group (OR=5.14, P = .29, NS).Conclusions: We conclude that the presence of more than 2 germline variants was probably associated with shorter survival of patients with localized prostate cancer qualified for radical treatment. The HOXB13 (G84E), CHEK2 (1100delC or IVS2+1G>A) truncating variants and NBS1 (I171V) are associated with PC and hereditary form of the disease. The HOXB13 (G84E) and NOD2 (3020insC) single variants are associated with shorter and CYP1B1 (48CC, 119GG) single genotypes with longer overall survival.

Genetics of prostate cancer and its utility in treatment and screening

Prostate cancer heritability is attributed to a combination of rare, moderate to highly penetrant genetic variants as well as commonly occurring variants conferring modest risks [single nucleotide polymorphisms (SNPs)]. Some of the former type of variants (e.g., BRCA2 mutations) predispose particularly to aggressive prostate cancer and confer poorer prognoses compared to men who do not carry mutations. Molecularly targeted treatments such as PARP inhibitors have improved outcomes in men carrying somatic and/or germline DNA repair gene mutations. Ongoing clinical trials are exploring other molecular targeted approaches based on prostate cancer somatic alterations. Genome wide association studies have identified >250 loci that associate with prostate cancer risk. Multi-ancestry analyses have identified shared as well as population specific risk SNPs. Prostate cancer risk SNPs can be used to estimate a polygenic risk score (PRS) to determine an individual's genetic risk of prostate cancer. The odds ratio of prostate cancer development in men whose PRS lies in the top 1% of the risk profile ranges from 9 to 11. Ongoing studies are investigating the utility of a prostate cancer PRS to target population screening to those at highest risk. With the advent of personalized medicine and development of DNA sequencing technologies, access to clinical genetic testing is increasing, and oncology guidelines from bodies such as NCCN and ESMO have been updated to provide criteria for germline testing of "at risk" healthy men as well as those with prostate cancer. Both germline and somatic prostate cancer research have significantly evolved in the past decade and will lead to further development of precision medicine approaches to prostate cancer treatment as well as potentially developing precision population screening models.