The association between germline BRCA2 variants and sensitivity to platinum-based chemotherapy among men with metastatic prostate cancer

The Genomic and Molecular Pathology of Prostate Cancer: Clinical Implications for Diagnosis, Prognosis, and Therapy

Prostate cancer (PCa) is the most common noncutaneous malignancy affecting American men and the second most common cause of cancer death. The traditional risk classification schemes for PCa are limited due to the vast clinical and molecular heterogeneity of the disease. Fortunately, recent advancements in sequencing technologies have provided us with valuable insight into the genomics of PCa. To date, a wide array of recurrent genomic alterations in PCa have been identified. Incorporating these distinct molecular subtypes of PCa into prediction models provides opportunities for improved risk stratification and ultimately better patient outcomes. In this review, we summarize the key molecular subtypes of PCa and focus on those genomic alterations that have clinical implications for diagnosis, prognosis, and therapeutic response.

BRCA2 gene mutation and prostate cancer risk. Comprehensive review and update

The second most common type of tumor worldwide is prostate cancer (PCa). Certain genetic factors contribute to a risk of developing PCa of as much as 40%. BRCA1 and BRCA2 mutations have linked with an increased risk for breast, ovarian, and PCa. However, BRCA2 is the most common gene found altered in early-onset of PCa in males younger than 65. BRCA2 mutation has a higher chance of developing an advanced stage of the disease, resulting in short survival time. This review aimed to describe the genetic changes in BRCA2 that contribute to the risk of PCa, to define its role in the early diagnosis in a man with a strong family history, and to outline the purpose of genetic testing and counseling. Also, the review summarizes the impact of BRCA2 gene mutation in localized PCa, and the treatment strategies have used for PCa patients with a BRCA2 modification.

Towards precision oncology in advanced prostate cancer

Metastatic biopsy programmes combined with advances in genomic sequencing have provided new insights into the molecular landscape of castration-resistant prostate cancer (CRPC), identifying actionable targets, and emerging resistance mechanisms. The detection of DNA repair aberrations, such as mutation of BRCA2, could help select patients for poly(ADP-ribose) polymerase (PARP) inhibitor or platinum chemotherapy, and mismatch repair gene defects and microsatellite instability have been associated with responses to checkpoint inhibitor immunotherapy. Poor prognostic features, such as the presence of RB1 deletion, might help guide future therapeutic strategies. Our understanding of the molecular features of CRPC is now being translated into the clinic in the form of increased molecular testing for use of these agents and for clinical trial eligibility. Genomic testing offers opportunities for improving patient selection for systemic therapies and, ultimately, patient outcomes. However, challenges for precision oncology in advanced prostate cancer still remain, including the contribution of tumour heterogeneity, the timing and potential cooperation of multiple driver gene aberrations, and diverse resistant mechanisms. Defining the optimal use of molecular biomarkers in the clinic, including tissue-based and liquid biopsies, is a rapidly evolving field.

Effect of DNA damage response mutations on prostate cancer prognosis: a systematic review

The prognosis of men with prostate cancer (PC) with mutations in DNA damage response (DDR) genes undergoing different treatments is unclear. This systematic review compared clinical outcomes in PC patients with DDR mutations (DDR⁺) versus no mutations (DDR^-). 14 resources plus gray literature were searched for studies in PC and subgroups (castration-resistant PC, metastatic PC and metastatic castration-resistant PC) by DDR gene (ATM, ATR, BRCA1, BRCA2, CHEK2, FANCA, MLH1, MRE11A, NBN, PALB2, RAD51C) mutation status. From 11,648 records, 26 studies were included. For mCRPC, six studies reported comparative efficacy for key outcomes. Improvements in several clinical outcomes were observed for DDR⁺ (vs DDR^-) after PARP inhibitor therapy or immunotherapy. DDR⁺ PC patients may have improved outcomes depending on the treatment they undergo.

Contribution of Inherited DNA-Repair Gene Mutations to Hormone-Sensitive and Castrate-Resistant Metastatic Prostate Cancer and Implications for Clinical Outcome

PURPOSE

To compare the prevalence of germline mutations in metastatic hormone-sensitive prostate cancer (mHSPC) and metastatic castrate-resistant prostate cancer (mCRPC) and assess the impact of mutations on progression to castration resistance and overall survival.

METHODS

Targeted sequencing of germline DNA from 704 men (221 at the time of mHSPC and 483 at the time of mCRPC) enrolled in two advanced prostate cancer registries at Mayo Clinic between 2003 and 2013 was performed for 21 predisposition genes. Frequencies of pathogenic mutations were compared in patients and reference controls to identify genes enriched in metastatic prostate cancer. Multivariable Cox proportional hazards regression was used to identify predictors of progression to mCRPC and overall survival.

RESULTS

Sixty-eight germline mutations in 12 genes were identified in 66 men (9.4%). Mutations in ATM, BRCA2, CHEK2, FANCM, and TP53 were significantly enriched (odds ratio greater than 2.0) in the metastatic cohorts compared with reference controls. The frequency of germline mutations was similar for patients with mHSPC and mCRPC (11.8% v 8.3%; P = .16). The median time to progression from mHSPC to mCRPC was 23.1 and 32.5 months for patients with and without mutations, respectively (P = .96). Although older age at diagnosis, Gleason score greater than 7, elevated alkaline phosphatase level, and high volume of disease were associated with shorter duration of progression to mCRPC and poor overall survival, mutation status was not (progression to mCRPC hazard ratio, 0.81; 95% CI, 0.61 to 1.09; P = .17; overall survival hazard ratio, 1.00; 95% CI, 0.75 to 1.34; P = .98).

CONCLUSION

Similarly elevated rates of germline predisposition gene mutations in mHSPC and mCRPC suggest that germline genetic testing may help to guide medical management for all patients with advanced metastatic prostate cancer. Mutation status was not associated with shorter progression to mCRPC or poor overall survival.

Cabazitaxel plus carboplatin for the treatment of men with metastatic castration-resistant prostate cancers: a randomised, open-label, phase 1-2 trial

BACKGROUND

Taxane-platinum combinations have shown promising activity in metastatic castration-resistant prostate cancers in single-group clinical studies but not in randomised trials. Distinct biological subsets of the disease might derive the greatest benefit from the addition of platinum. We aimed to determine whether adding carboplatin to cabazitaxel would improve the outcomes of men with metastatic castration-resistant prostate cancer.

METHODS

We did a phase 1-2, open label, randomised study at two centres in men with progressive metastatic castration-resistant prostate cancer. In phase 1, patients received intravenous cabazitaxel 20-25 mg/m² and intravenous carboplatin area under the curve (AUC) 3-4 mg/mL per min every 21 days. The maximum tolerated dose was defined as the highest dose cohort studied in which one of six or fewer patients experienced a dose-limiting toxicity. In phase 2, patients were randomly assigned (1:1) centrally by a computerised algorithm to intravenous cabazitaxel 25 mg/m² with or without intravenous carboplatin AUC 4 mg/mL per min. All patients received growth factor support and oral prednisone 10 mg daily. The primary endpoints were the maximum tolerated dose of the combination in phase 1 and investigator-assessed progression-free survival in phase 2. This trial is registered at ClinicalTrials.gov, number NCT01505868.

FINDINGS

Between Aug 17, 2012, and May 11, 2015, nine patients completed phase 1 as planned, and 160 were randomly assigned to cabazitaxel (n=79) or cabazitaxel plus carboplatin (n=81) in phase 2. During phase I, grade 3 adverse events were anaemia (n=2), fatigue (n=1), thrombocytopenia (n=1), hypomagnesaemia (n=1), diarrhoea (n=1), hypokalaemia (n=1), anorexia (n=1), and dehydration (n=1), and no grade 4 adverse events occurred. No dose-limiting toxicities were observed, therefore, a maximum tolerated dose of cabazitaxel of 25 mg/m² and carboplatin of AUC 4 mg/mL per min was selected for phase 2. At a median follow-up of 31·0 months (IQR 20·5-37·1), the combination improved the median progression-free survival from 4·5 months (95% CI 3·5-5·7) to 7·3 months (95% CI 5·5-8·2; hazard ratio 0·69, 95% CI 0·50-0·95, p=0·018). In the phase 2 study, the most common grade 3-5 adverse events were fatigue (7 [9%] of 79 in the cabazitaxel group vs 16 [20%] of 81 in the combination group), anaemia (3 [4%] vs 19 [23%]), neutropenia (3 [4%] vs 13 [16%]), and thrombocytopenia (1 [1%] vs 11 [14%]). There were no treatment-related deaths.

INTERPRETATION

Carboplatin added to cabazitaxel showed improved clinical efficacy compared with cabazitaxel alone for men with metastatic castration-resistant prostate cancer. Although adverse events were more common with the combination, the treatment was safe and generally well tolerated. Our data suggest that taxane-platinum combinations have a clinically beneficial role in advanced prostate cancer and a randomised phase 3 study is planned.

FUNDING

Sanofi Genzyme, University of Texas MD Anderson Cancer Center Prostate Cancer Moon Shot Program, and Solon Scott III Prostate Cancer Research Fund.

Emerging therapeutic agents for genitourinary cancers

The treatment of genitourinary malignancies has dramatically evolved over recent years. Renal cell carcinoma, urothelial carcinoma of the bladder, and prostate adenocarcinoma are the most commonly encountered genitourinary malignancies and represent a heterogeneous population of cancers, in both histology and approach to treatment. However, all three cancers have undergone paradigm shifts in their respective therapeutic landscapes due to a greater understanding of their underlying molecular mechanisms and oncogenic drivers. The advance that has gained the most recent traction has been the advent of immunotherapies, particularly immune checkpoint inhibitors. Immunotherapy has increased overall survival and even provided durable responses in the metastatic setting in some patients. The early success of immune checkpoint inhibitors has led to further drug development with the emergence of novel agents which modulate the immune system within the tumor microenvironment. Notwithstanding immunotherapy, investigators are also developing novel agents tailored to a variety of targets including small-molecule tyrosine kinase inhibitors, mTOR inhibitors, and novel fusion proteins to name a few. Erdafitinib has become the first targeted therapy approved for metastatic bladder cancer. Moreover, the combination therapy of immune checkpoint inhibitors with targeted agents such as pembrolizumab or avelumab with axitinib has demonstrated both safety and efficacy and just received FDA approval for their use. We are in an era of rapid progression in drug development with multiple exciting trials and ongoing pre-clinical studies. We highlight many of the promising new emerging therapies that will likely continue to improve outcomes in patients with genitourinary malignancies.

A systematic review of the prevalence of DNA damage response gene mutations in prostate cancer

Several ongoing international prostate cancer (PC) clinical trials are exploring therapies that target the DNA damage response (DDR) pathway. This systematic review summarizes the prevalence of DDR mutation carriers in the unselected (general) PC and familial PC populations. A total of 11 electronic databases, 10 conference proceedings, and grey literature sources were searched from their inception to December 2017. Studies reporting the prevalence of somatic and/or germline DDR mutations were summarized. Metastatic PC (mPC), castration‑resistant PC (CRPC) and metastatic CRPC (mCRPC) subgroups were included. A total of 11,648 records were retrieved, and 80 studies (103 records) across all PC populations were included; 59 records were of unselected PC and 13 records of familial PC. Most data were available for DDR panels (n=12 studies), ataxia telangiectasia mutated (ATM; n=13), breast cancer susceptibility gene (BRCA)1 (n=14) and BRCA2 (n=20). ATM, BRCA2 and partner and localizer of BRCA2 (PALB2) had the highest mutation rates (≥4%). Median prevalence rates for DDR germline mutations were 18.6% in PC (range, 17.2‑19%; three studies, n=1,712), 11.6% in mPC (range, 11.4‑11.8%; two studies, n=1,261) and 8.3% in mCRPC (range, 7.5‑9.1%; two studies, n=738). Median prevalence rates for DDR somatic mutations were 10.7% in PC (range, 4.9‑22%; three studies, n=680), 13.2% in mPC (range, 10‑16.4%; two studies, n=105) and not reported (NR) in mCRPC. The prevalence of DDR germline and/or somatic mutations was 27% in PC (one study, n=221), 22.67% in mCRPC (one study, n=150) and NR in mPC. In familial PC, median mutation prevalence was 12.1% (range, 7.3‑16.9%) for germline DDR (two studies, n=315) and 3.7% (range, 1.3‑7.9%) for BRCA2 (six studies, n=945). In total, 88% of studies were at a high risk of bias. The prevalence of DDR gene mutations in PC varied widely within somatic subgroups depending on study size, genetic screening techniques, DDR mutation definition and PC diagnosis; somatic and/or germline DDR mutation prevalence was in the range of 23‑27% in PC. These findings support DDR mutation testing for all patients with PC (including those with mCRPC). With the advent of the latest clinical practice PC guidelines highlighting the importance of DDR mutation screening, and ongoing mCRPC clinical trials evaluating DDR mutation‑targeted drugs, future larger epidemiological studies are warranted to further quantify the international burden of DDR mutations in PC.

Multi-omics analysis reveals the BRCA1 mutation and mismatch repair gene signatures associated with survival, protein expression, and copy number alterations in prostate cancer

BACKGROUND

Recent genomic analysis reveals that DNA repair gene mutations can be detected in 15-30% of patients in metastatic castration resistant prostate cancer depending on the population and clinical setting when comparing to a very small fraction in those with indolent localized diseases. The discovery and characterization of function associated with DNA repair gene mutations in prostate cancer patients may increase therapeutic options and lead to improved clinical outcomes.

METHODS

To understand the role of DNA repair genes associated with other genomic alteration and signaling pathway, we applied an integrative analysis of multi-omics to The Cancer Genome Atlas (TCGA) prostate cancer dataset which contains 498 patients. We concurrently analyzed gene expression profiles, reverse phase protein lysate microarray (RPPA) data, and copy number alterations to examine the potential genomic mechanisms.

RESULTS

We identified the signature of "chromosome condensation", "BRCA1 mutation", and "mismatch repair" were associated with disease-free survival in prostate cancer. Through the concurrent analysis of gene expression profiles, reverse RPPA data, and copy number alterations, we found the three signatures are associated with cell cycle and DNA repair pathway and also most events of copy number gains.

CONCLUSIONS

This study presents a unique extension from DNA mutations to expressional functions, proteomic activities, and copy numbers of DNA repair genes in prostate cancer. Our findings revealed crucial prognostic markers and candidates for further biological and clinical investigations.

Molecular Testing Identifies Determinants of Exceptional Response and Guides Precision Therapy in a Patient with Lethal, Treatment-emergent Neuroendocrine Prostate Cancer

Nearly all prostate cancers start out as adenocarcinomas driven by the androgen receptor (AR). Neuroendocrine prostate cancer (NEPC) is a rare, AR-independent subtype with a poor prognosis and limited treatment options. Importantly, because of the widespread use of novel AR-targeting agents, the incidence of treatment-emergent (t)-NEPC is increasing in frequency. Molecular features commonly found in prostate adenocarcinomas are now well-recognized, including defects in homologous recombination (HR) genes, like breast cancer type 2 susceptibility protein (BRCA2), leading to increased sensitivity to deoxyribonucleic acid (DNA)-damaging agents (e.g., platinum chemotherapy or poly adenosine diphosphate-ribose polymerase (PARP) inhibitors). However, our own prior work demonstrates that HR gene defects are uncommon in t-NEPC. Herein, we describe a patient who originally presented with adenocarcinoma but who subsequently developed t-NEPC. Molecular testing determined that his t-NEPC tumor (but not his original adenocarcinoma) harbored complete copy number loss of BRCA2, as well as copy number loss of another HR gene - ataxia telangiectasia, mutated (ATM). Uncharacteristically for t-NEPC, the patient achieved a complete response to platinum chemotherapy. Based on emerging data for the role of maintenance PARP inhibitor therapy in ovarian cancer patients whose tumors harbor BRCA1/2 defects, we treated him with PARP inhibitor maintenance after chemotherapy. At nine months follow-up, the patient was still in complete remission. This report demonstrates the importance of molecular testing to clarify the biology of exceptional responders and to direct treatment. Our results also suggest that clinical trials of PARP inhibitor maintenance may be warranted in select patients with advanced prostate cancer, including those with t-NEPC, whose tumors harbor HR defects.

Targeting the androgen receptor and overcoming resistance in prostate cancer

PURPOSE OF REVIEW

Prostate cancer (PCa) is diagnosed in one out of every nine men and is the second leading cause of cancer death among men. Although therapies targeting the androgen receptor (AR) are highly effective, development of resistance is universal and remains a major therapeutic challenge. Nonetheless, signaling via AR is frequently maintained despite standard androgen-signaling inhibition. We review the current understanding of mechanisms of resistance as well as therapeutic approaches to improving treatment of PCa via targeting of the AR.

RECENT FINDINGS

Resistance to AR-targeting therapies may be mediated by several mechanisms, including amplification, mutation, and alternative splicing of AR; intratumoral androgen synthesis; activation of alternative signaling pathways; and in a minority of cases, emergence of AR-independent phenotypes. Recent trials demonstrate that intensification of androgen blockade in metastatic castration-sensitive PCa can significantly improve survival. Similar strategies are being explored in earlier disease states. In addition, several other cellular signaling pathways have been identified as mechanisms of resistance, offering opportunities for cotargeted therapy. Finally, immune-based approaches are in development to complement AR-targeted therapies.

SUMMARY

Targeting the AR remains a critical focus in the treatment of PCa.

Germline and Somatic Mutations in Prostate Cancer for the Clinician

It is increasingly important for clinicians involved in the management of prostate cancer to understand the relevance of heritable (germline) mutations that, for select patients, affect prostate cancer risk and cancer biology, and acquired (somatic) mutations that occur in prostate cancer cells. In the advanced disease setting, mutations in homologous recombination repair genes (eg, BRCA1, BRCA2, ATM, CHEK2, PALB2) suggest candidacy for platinum chemotherapy and PARP inhibitor trials. Similarly, microsatellite instability and mismatch repair deficiency, which may arise in the setting of MLH1, MSH2, MSH6, and PMS2 mutations, suggest potential vulnerability to PD-1 inhibitors. Germline genetic testing has potential importance in the treatment and assessment of familial risk, and tumor-directed somatic sequencing may guide treatment decision-making. This review provides clinicians with knowledge of basic genetic terminology, awareness of the importance of family history of cancer (not limited to prostate cancer), contrasts between the different but potentially related objectives of germline versus somatic testing of tumor tissue, and indications for genetic counseling. Specific clinical scenarios, objectives of testing, and nature of the assays are reviewed. Germline and somatic mutations of known and potential relevance to prostate cancer are discussed in the context of treatment options, and algorithms to assist clinicians in approaching this area are proposed.

Outcomes of universal germline testing for men with prostate cancer in an Australian tertiary center

AIM

The role of germline testing in prostate cancer is evolving and knowledge of an individual's genetic profile may be used to guide not only an assessment of their familial risk but also have prognostic and therapeutic implications. Although international guidelines have incorporated recommendations for germline testing in prostate cancer, there is little Australian data to guide referrals. The aim of this study is to review the frequency of relevant pathogenic mutations in an Australian center, their associated clinical factors and clinical impact.

METHODS

We conducted a single-center retrospective review of men with prostate cancer that undertook prospective germline testing using a targeted next generation sequencing panel.

RESULTS

Results for 100 men were analyzed. Median age at diagnosis was 62 years (range 43-84); 92% had metastatic disease at referral. A pathogenic mutation was confirmed in 9%, a likely pathogenic variant in 2% and a variant of uncertain significance in 15%. Age ≤60 years was associated with an increased risk for a pathogenic germline variant (P = 0.0096). Two of the nine (22%) with pathogenic variants went on to receive targeted treatment.

CONCLUSIONS

In this single center study, the incidence of germline mutations in genes associated with DNA-repair was consistent with rates seen previously published international series of men with metastatic disease. A pathogenic variant was only seen in one patient >60 years of age and no man referred solely on the basis of age or high-risk localized disease had a relevant finding.

Prevalence of Germline Variants in Prostate Cancer and Implications for Current Genetic Testing Guidelines

IMPORTANCE

Prostate cancer is the third leading cause of cancer-related death in men in the United States. Although serious, most of these diagnoses are not terminal. Inherited risk for prostate cancer is associated with aggressive disease and poorer outcomes, indicating a critical need for increased genetic screening to identify disease-causing variants that can pinpoint individuals at increased risk for metastatic castration-resistant prostate cancer.

OBJECTIVE

To identify positive (pathogenic, likely pathogenic, and increased risk) germline variants in a large prostate cancer cohort and to evaluate the usefulness of current practice guidelines in recognizing individuals at increased risk for prostate cancer who would benefit from diagnostic genetic testing.

DESIGN, SETTING, AND PARTICIPANTS

Cross-sectional study of data from 3607 men with a personal history of prostate cancer who underwent germline genetic testing between 2013 and 2018 and were unselected for family history, stage of disease, or age at diagnosis. Referral-based testing was performed at a Clinical Laboratory Improvement Amendments/College of American Pathologists-certified diagnostic laboratory. All analysis took place between February 2017 and August 2018.

MAIN OUTCOMES AND MEASURES

The frequency and distribution of positive germline variants, and the percentage of individuals with prostate cancer who met National Comprehensive Cancer Network (NCCN) guidelines for germline genetic testing.

RESULTS

Of 3607 men (mean [SD] age at testing, 67 [9.51] years; mean age at diagnosis, 60 [9.05] years) with a personal diagnosis of prostate cancer who were referred for genetic testing, 620 (17.2%) had positive germline variants, of which only 30.7% were variants in BRCA1/2. Positive variants in HOXB13, a gene associated only with prostate cancer risk, were identified in 30 patients (4.5%). DNA mismatch repair variants with substantial known therapeutic implications were detected in 1.74% of variants in the total population tested. Examination of self-reported family histories indicated that 229 individuals (37%) with positive variants in this cohort would not have been approved for genetic testing using the NCCN genetic/familial breast and ovarian guidelines for patients with prostate cancer.

CONCLUSIONS AND RELEVANCE

Current NCCN guidelines and Gleason scores cannot reliably stratify patients with prostate cancer for the presence or absence of pathogenic germline variants. Most positive genetic test results identified in this study have important management implications for patients and their families, which underscores the need to revisit current guidelines.

BRCA2 and Other DDR Genes in Prostate Cancer

Germline and somatic aberrations in DNA damage repair (DDR) genes are more prevalent in prostate cancer than previously recognized, with BRCA2 as the most commonly altered gene. Germline mutations in BRCA2 have been linked to poor prognosis when patients are managed under the protocols currently approved for prostate cancer. The impact of germline mutations in other DDR genes beyond BRCA2 remain unclear. Importantly, a quarter of prostate cancer patients identified as germline mutation carriers lack a family history of cancer. The clinical implications of somatic DDR defects are yet to be elucidated. Poly ADP-ribose polymerase (PARP) inhibitors and platinum-based chemotherapy have proven to be effective in the treatment of other tumor types linked to BRCA1 and BRCA2 alterations and several trials are currently evaluating their efficacy in prostate cancer. Here, we summarize the available evidence regarding the prevalence of somatic and germline DDR defects in prostate cancer; their association with clinical outcomes; the trials assessing the efficacy of new therapies that exploit DDR defects in prostate cancer and briefly discuss some uncertainties about the most appropriate management for these patients.

Prevalence of DNA repair gene mutations in localized prostate cancer according to clinical and pathologic features: association of Gleason score and tumor stage

BACKGROUND

DNA repair gene mutations are present in 8-10% of localized prostate cancers. It is unknown whether this is influenced by clinicopathologic factors.

METHODS

We interrogated localized prostate adenocarcinomas with tumor DNA sequencing information from the TCGA validated (n = 333) and Nature Genetics (n = 377) datasets. Homologous recombination repair genes included in our analysis were: ATM, BRCA1/2, CDK12, CHEK1/2, FANCA, FANCD2, FANCL, GEN1, NBN, PALB2, RAD51, and RAD51C. Proportions of cases with pathogenic DNA repair mutations (and in ATM/BRCA1/2 specifically) were reported by Gleason grade group, clinical T, pathologic T, and pathologic N stage. Odds ratios and Fisher's exact tests were used to compare proportions between categories.

RESULTS

Patients with Gleason grade groups 3 and higher were 2.2 times more likely to harbor any DNA repair mutation (95% CI: 1.2-4.2; 10.3% versus 5.0%) and were 2.7 times more likely to have BRCA1/2 or ATM mutations (95% CI: 1.3-6.6; 7.0% versus 2.7%) compared to those in Gleason grade groups 1-2. Patients with pathologic T3 and T4 stage (pT3/pT4) were 2.6 times more likely to have any DNA repair mutation (95% CI: 1.3-6.6; 13.0% versus 5.5%) and were 3.2 times more likely to have BRCA1/2 or ATM mutations (95% CI: 1.2-11.3; 9.5% versus 3.1%) compared to those with pT2 disease. There was no difference by clinical tumor or nodal stage. Among men with Gleason grade group ≥ 3 and clinical stage ≥ cT3, 21.3% (1 in 5) had a DNA repair mutation in any gene and 11.7% (1 in 9) had a mutation in ATM/BRCA1/2.

CONCLUSIONS

The prevalence of pathogenic DNA repair gene alterations is enriched in men with advanced tumor stages and higher Gleason grade groups, with maximal enrichment observed in those with Gleason grade group ≥ 3 and clinical stage ≥ cT3 disease. This information can be used to guide eligibility criteria for genomically targeted clinical trials in the neoadjuvant/adjuvant settings.

PROREPAIR-B: A Prospective Cohort Study of the Impact of Germline DNA Repair Mutations on the Outcomes of Patients With Metastatic Castration-Resistant Prostate Cancer

PURPOSE

Germline mutations in DNA damage repair (DDR) genes are identified in a significant proportion of patients with metastatic prostate cancer, but the clinical implications of these genes remain unclear. This prospective multicenter cohort study evaluated the prevalence and effect of germline DDR (gDDR) mutations on metastatic castration-resistance prostate cancer (mCRPC) outcomes.

PATIENTS AND METHODS

Unselected patients were enrolled at diagnosis of mCRPC and were screened for gDDR mutations in 107 genes. The primary aim was to assess the impact of ATM/BRCA1/BRCA2/ PALB2 germline mutations on cause-specific survival (CSS) from diagnosis of mCRPC. Secondary aims included the association of gDDR subgroups with response outcomes for mCRPC treatments. Combined progression-free survival from the first systemic therapy (PFS) until progression on the second systemic therapy (PFS2) was also explored.

RESULTS

We identified 68 carriers (16.2%) of 419 eligible patients, including 14 with BRCA2, eight with ATM, four with BRCA1, and none with PALB2 mutations. The study did not reach its primary end point, because the difference in CSS between ATM/BRCA1/BRCA2/PALB2 carriers and noncarriers was not statistically significant (23.3 v 33.2 months; P = .264). CSS was halved in germline BRCA2 (g BRCA2) carriers (17.4 v 33.2 months; P = .027), and g BRCA2 mutations were identified as an independent prognostic factor for CCS (hazard ratio [HR], 2.11; P = .033). Significant interactions between g BRCA2 status and treatment type (androgen signaling inhibitor v taxane therapy) were observed (CSS adjusted P = .014; PFS2 adjusted P = .005). CSS (24.0 v 17.0 months) and PFS2 (18.9 v 8.6 months) were greater in g BRCA2 carriers treated in first line with abiraterone or enzalutamide compared with taxanes. Clinical outcomes did not differ by treatment type in noncarriers.

CONCLUSION

g BRCA2 mutations have a deleterious impact on mCRPC outcomes that may be affected by the first line of treatment used. Determination of g BRCA2 status may be of assistance for the selection of the initial treatment in mCRPC. Nonetheless, confirmatory studies are required before these results can support a change in clinical practice.

Germline and Somatic Defects in DNA Repair Pathways in Prostate Cancer

Recent studies have provided a better understanding of the molecular underpinnings of prostate cancer. Alterations in genes encoding for proteins involved in the different pathways in charge of preserving genomic integrity and repairing DNA damage are common in prostate cancer, particularly in late-stage disease. Generally, these alterations would confer a survival advantage for tumors, resulting in a more aggressive phenotype. However, DNA repair defects can also represent a vulnerability for tumors that can be exploited therapeutically, offering the possibility of precision medicine strategies. Moreover, many of these mutations are linked to hereditary risk for cancers; hence, identification of DNA repair mutations could also be relevant for cancer prevention and screening in healthy individuals, including relatives of prostate cancer patients. In this chapter, we summarize current knowledge about the prevalence of different DNA repair gene alterations across different stages of prostate cancer and review the clinical relevance of such events in terms of prognosis and treatment stratification.

Genitourinary Pathology Reporting Parameters Most Relevant to the Medical Oncologist

Pathologic variables play an important role in prognostication in urologic malignancies. Histologic subtype, histologic grade, and anatomic extent of disease (pathologic tumor and nodal staging) influence treatment decisions in both the adjuvant and metastatic settings. This article discusses treatment paradigms for the most common urologic malignancies, followed by the evidence base to support the relationship between pathologic assessment and decision making by the medical oncologist.

DNA repair defects in prostate cancer: impact for screening, prognostication and treatment

Failure of effective DNA damage repair is a hallmark of cancer, but was previously underappreciated as a driver of aggressive prostate cancer. However, recent international sequencing efforts have revealed that both germline and somatic alterations within the homologous recombination and mismatch repair pathways are relatively common in lethal metastatic disease. BRCA2 gene alterations are particularly prevalent and are linked to poor prognosis as well as poor responses to systemic therapy for castration-resistant prostate cancer, although there is conflicting support for the latter. Defective DNA repair contributes to tumour heterogeneity, evolution and progression, but there are high hopes that management of this aggressive subset will be transformed by biomarker-driven use of poly-ADP ribose polymerase (PARP) inhibitors and platinum-based chemotherapy. In this review, we detail the relationship between DNA repair defects and prostate cancer, highlighting the prevalence of mutations in key genes and their controversial association with clinical outcomes.

Developments in urologic oncology "OncoForum": The best of 2017

OBJECTIVE

To put forth new findings of urologic oncology with impact on clinical practice presented during 2017 in the main annual meetings.

METHODS

This document reviews abstracts on prostate, kidney and bladder cancer presented at the congresses of 2016 (EAU, AUA, ASCO, ESMO and ASTRO) and publications with the highest impact in this period valued with the highest scores by the OncoForum committee.

RESULTS

Among patients at high risk of recurrent renal cell carcinoma after nephrectomy, adjuvant sunitinib compared to placebo showed a benefit in patients at higher risk of recurrence. In cisplatin-ineligible advanced urothelial cancer, pembrolizumab elicits clinically meaningful, durable responses. Among patients with localized prostate cancer, treatment for disease progression was less frequent (absolute difference, 26.2 percentage pontis) and adverse events was more frequent with surgery than with observation. Among patients with locally advanced or merastatic prostate cancer, androgen-deprivation therapy plus abiraterone and prednisolone resulted in fewer deaths and fewer treatment-failure events (P<.001). Among patients with metastatic castration-resistant prostate cancer previously treated with abiraterone acetate, enzalutamide median radiographic progression free survival was 8,1 months and enzalutamide median overall survival was not reached.

CONCLUSIONS

Among patients at high risk of recurrent renal cell carcinoma after nephrectomy, adjuvant sunitinib showed a benefit across subgroups including patients at higher risk of recurrence. Among patients with localized prostate cancer, surgery was not associated with significantly lower all-cause or porstate-cancer mortality than observation. Among patients with locally advanced or merastatic prostate cancer, androgen-deprivation therapy plus abiraterone and prednisolone was associated with significantly higher rates of overall and failure-free survival than androgen-deprivation therapy alone. In patients with metastatic castration-resistant prostate cancer previously treated with abiraterone enzalutamide remained active.

Aberrations of DNA Repair Pathways in Prostate Cancer: Future Implications for Clinical Practice?

Patients who are carriers of inherited mutations in essential component of DNA repair pathways have a significantly higher lifetime risk for developing cancer compared to the population of reference. Recent advances in DNA next-generation sequencing technology have allowed screening for carriers of those mutations, allowing development of promising risk-reduction strategies and providing the rationale to personalize the therapeutic approach for these patients. New intriguing scenarios are opening nowadays for the management of prostate cancer in patients with germline or somatic mutations in components of DNA repair pathways (e.g., BRCA1 and BRCA2 genes), such as specific screening policies and new therapeutic strategies involving PARP inhibitors or platinum-based chemotherapy.

A PDX/Organoid Biobank of Advanced Prostate Cancers Captures Genomic and Phenotypic Heterogeneity for Disease Modeling and Therapeutic Screening

Purpose: Prostate cancer translational research has been hampered by the lack of comprehensive and tractable models that represent the genomic landscape of clinical disease. Metastatic castrate-resistant prostate cancer (mCRPC) patient-derived xenografts (PDXs) recapitulate the genetic and phenotypic diversity of the disease. We sought to establish a representative, preclinical platform of PDX-derived organoids that is experimentally facile for high-throughput and mechanistic analysis.Experimental Design: Using 20 models from the LuCaP mCRPC PDX cohort, including adenocarcinoma and neuroendocrine lineages, we systematically tested >20 modifications to prostate organoid conditions. Organoids were evaluated for genomic and phenotypic stability and continued reliance on the AR signaling pathway. The utility of the platform as a genotype-dependent model of drug sensitivity was tested with olaparib and carboplatin.Results: All PDX models proliferated as organoids in culture. Greater than 50% could be continuously cultured long-term in modified conditions; however, none of the PDXs could be established long-term as organoids under previously reported conditions. In addition, the modified conditions improved the establishment of patient biopsies over current methods. The genomic heterogeneity of the PDXs was conserved in organoids. Lineage markers and transcriptomes were maintained between PDXs and organoids. Dependence on AR signaling was preserved in adenocarcinoma organoids, replicating a dominant characteristic of CRPC. Finally, we observed maximum cytotoxicity to the PARP inhibitor olaparib in BRCA2-/- organoids, similar to responses observed in patients.Conclusions: The LuCaP PDX/organoid models provide an expansive, genetically characterized platform to investigate the mechanisms of pathogenesis as well as therapeutic responses and their molecular correlates in mCRPC. Clin Cancer Res; 24(17); 4332-45. ©2018 AACR.

Evolving Intersection Between Inherited Cancer Genetics and Therapeutic Clinical Trials in Prostate Cancer: A White Paper From the Germline Genetics Working Group of the Prostate Cancer Clinical Trials Consortium

Purpose

Advances in germline genetics, and related therapeutic opportunities, present new opportunities and challenges in prostate cancer. The Prostate Cancer Clinical Trials Consortium Germline Genetics Working Group was established to address genetic testing for men with prostate cancer, especially those with advanced disease undergoing testing for treatment-related objectives and clinical trials.

Methods

The Prostate Cancer Clinical Trials Consortium Germline Genetics Working Group met monthly to discuss the current state of genetic testing of men with prostate cancer for therapeutic or clinical trial purposes. We assessed current institutional practices, developed a framework to address unique challenges in this population, and identified areas of future research.

Results

Genetic testing practices in men with prostate cancer vary across institutions; however, there were several areas of agreement. The group recognized the clinical benefits of expanding germline genetic testing, beyond cancer risk assessment, for the goal of treatment selection or clinical trial eligibility determination. Genetic testing for treatment selection should ensure patients receive appropriate pretest education and consent and occur under auspices of a research study whenever feasible. Providers offering genetic testing should be able to interpret results and recommend post-test genetic counseling for patients. When performing tumor (somatic) genomic profiling, providers should discuss the potential for uncovering germline mutations and recommend appropriate genetic counseling. In addition, family members may benefit from cascade testing and early cancer screening and prevention strategies.

Conclusion

As germline genetic testing is incorporated into practice, further development is needed in establishing prompt testing for time-sensitive treatment decisions, integrating cascade testing for family, ensuring equitable access to testing, and elucidating the role of less-characterized germline DNA damage repair genes, individual gene-level biologic consequences, and treatment response prediction in advanced disease.

Structural Alterations Driving Castration-Resistant Prostate Cancer Revealed by Linked-Read Genome Sequencing

Nearly all prostate cancer deaths are from metastatic castration-resistant prostate cancer (mCRPC), but there have been few whole-genome sequencing (WGS) studies of this disease state. We performed linked-read WGS on 23 mCRPC biopsy specimens and analyzed cell-free DNA sequencing data from 86 patients with mCRPC. In addition to frequent rearrangements affecting known prostate cancer genes, we observed complex rearrangements of the AR locus in most cases. Unexpectedly, these rearrangements include highly recurrent tandem duplications involving an upstream enhancer of AR in 70%-87% of cases compared with <2% of primary prostate cancers. A subset of cases displayed AR or MYC enhancer duplication in the context of a genome-wide tandem duplicator phenotype associated with CDK12 inactivation. Our findings highlight the complex genomic structure of mCRPC, nominate alterations that may inform prostate cancer treatment, and suggest that additional recurrent events in the non-coding mCRPC genome remain to be discovered.

Practical Methods for Integrating Genetic Testing Into Clinical Practice for Advanced Prostate Cancer

Recent advances clearly demonstrate the potential clinical relevance of germline genetic testing and somatic genomic profiling in identifying possible therapeutic and/or clinical trial options, particularly in advanced prostate cancer. In addition, if a germline genetic mutation/pathogenic variant is identified, there may be important family implications and possible life-saving changes to healthcare management. However, there is substantial debate and uncertainty about how best to offer genetic testing services, which tests to use, which patients to test, what sequence of testing, what timing, by whom, and with what kind of follow-up. To help address this new area of potential benefit and confusion, we provide a practical overview of recent advances, discuss options and considerations for both germline and somatic testing, and offer practical advice on what providers should understand before referring and/or ordering testing, key discussion points for patients and families, and available genetics resources.

Prostate cancer in the era of "Omic" medicine: recognizing the importance of DNA damage repair pathways

Data from recent high-throughput studies analyzing local and advanced prostate cancer have revealed an incredible amount of biological diversity, which has led to the classification of distinct molecular tumor subtypes. While integrating prostate cancer genomics with clinical medicine is still at its infancy, new approaches to treat prostate cancer are well underway and being studied. With the recognition that DNA damage repair (DDR) mutations play an important role in the pathogenesis of this disease, clinicians can begin to utilize genomic information in complex treatment decisions for prostate cancer patients. In this Review, we discuss the role of DDR mutations in prostate cancer, including deficiencies in homologous repair and mismatch repair (MMR), and how this information is revolutionizing the treatment landscape. In addition, we highlight the potential resistance mechanisms that may result as we begin to target these pathways in isolation and discuss potential combinatorial approaches that may delay or overcome resistance.

The resounding effect of DNA repair deficiency in prostate cancer

An estimated one-fifth or more of metastatic castration-resistant prostate cancer (mCRPC) harbor defects in genes involved in DNA repair pathway (e.g., BRCA2, BRCA1, and others). Early evidence suggests these alterations may be predictive of therapeutic response to PARP inhibitors and platinum chemotherapy, thought to reflect principles of synthetic lethality and are currently being investigated in an increasing number of prospective clinical trials. Other studies have examined these alterations as prognostic biomarkers and in association with response to currently available treatments. A smaller fraction of men (5%-10%) with mCRPC have evidence of microsatellite instability and defects in the DNA mismatch repair pathway, which may predict therapeutic response to immune checkpoint inhibitors. Loss of function of these 2 critical DNA repair pathways serves as new candidate predictive biomarkers for treatment strategies that represent net gains in the treatment toolbox for prostate cancer. Additionally, more than one-tenth of men with mCRPC carry genetic alterations of DNA repair in their germline DNA, which may indicate high- to moderate-penetrance heritable cancer risk and have important implications for family members. Cascade genetic testing of family can, in some cases, direct modified strategies for screening and prevention of multiple cancers. Further study in each of these arenas is ongoing, although the potential for resounding effect is clear.

Germline DNA-repair Gene Mutations and Outcomes in Men with Metastatic Castration-resistant Prostate Cancer Receiving First-line Abiraterone and Enzalutamide

BACKGROUND

Inherited DNA-repair gene mutations are more prevalent in men with advanced prostate cancer than previously thought, but their clinical implications are not fully understood.

OBJECTIVE

To investigate the clinical significance of germline DNA-repair gene alterations in men with metastatic castration-resistant prostate cancer (mCRPC) receiving next-generation hormonal therapy (NHT), with a particular emphasis on BRCA/ATM mutations.

DESIGN, SETTING, AND PARTICIPANTS

We interrogated 50 genes for pathogenic or likely pathogenic germline mutations using leukocyte DNA from 172 mCRPC patients beginning treatment with first-line NHT with abiraterone or enzalutamide.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

We assessed the impact of germline DNA-repair gene mutation status on ≥50% and ≥90% PSA responses, PSA progression-free survival (PSA-PFS), clinical/radiologic progression-free survival (PFS), and overall survival (OS). Survival outcomes were adjusted using propensity score-weighted multivariable Cox regression analyses.

RESULTS AND LIMITATIONS

Among 172 mCRPC patients included, germline mutations (in any DNA-repair gene) were found in 12% (22/172) of men, and germline BRCA/ATM mutations specifically in 5% (9/172) of men. In unadjusted analyses, outcomes to first-line NHT were better in men with germline BRCA/ATM mutations (vs no mutations) with respect to PSA-PFS (hazard ratio [HR] 0.47; p=0.061), PFS (HR 0.50; p=0.090), and OS (HR 0.28; p=0.059). In propensity score-weighted multivariable analyses, outcomes were superior in men with germline BRCA/ATM mutations with respect to PSA-PFS (HR 0.48, 95% confidence interval [CI] 0.25-0.92; p=0.027), PFS (HR 0.52, 95% CI 0.28-0.98; p=0.044), and OS (HR 0.34, 95% CI 0.12-0.99; p=0.048), but not in men with non-BRCA/ATM germline mutations (all p>0.10). These results require prospective validation, and our conclusions are limited by the small number of patients (n=9) with BRCA/ATM mutations.

CONCLUSIONS

Outcomes to first-line NHT appear better in mCRPC patients harboring germline BRCA/ATM mutations (vs no mutations), but not for patients with other non-BRCA/ATM germline mutations.

PATIENT SUMMARY

Patients with metastatic castration-resistant prostate cancer and harboring germline mutations in BRCA1/2 and ATM benefit from treatment with abiraterone and enzalutamide.

CTC-derived AR-V7 detection as a prognostic and predictive biomarker in advanced prostate cancer

INTRODUCTION

Prostate cancer is a highly heterogeneous disease, with remarkably different prognosis across all stages. Increased circulating tumor cell (CTC) count (≥ 5) using the CellSearch assay has been identified as one of the markers that can be used to predict survival, with added value beyond currently available prognostic factors. Recently, androgen receptor splice variant 7 (AR-V7) detection has been associated with worse outcomes for patients with castration-resistant prostate cancer (CRPC) treated with novel androgen receptor-signaling (ARS) inhibitors such as abiraterone and enzalutamide but not taxane chemotherapies. Areas covered: In this manuscript, the authors review the available biomarkers in CRPC and discuss emerging data on the value of CTC-derived AR-V7 status to assess prognosis and its potential role to guide treatment selection for patients with advanced prostate cancer. Expert commentary: Current evidence supports AR-V7 status as a prognostic biomarker and also as a potential predictive biomarker for patients with mCRPC. The authors expect that the incorporation of AR-V7 status and other biomarkers (e.g. AR mutations) in the sequential assessment of patients with advanced prostate cancer will lead to a more rational use of available and future therapies, with significant improvements in outcomes for our patients.

Platinum sensitivity in metastatic prostate cancer: does histology matter?

BACKGROUND

Platinum-based chemotherapy is effective in men with neuroendocrine prostate cancer (NEPC), but it is unclear whether histology (adenocarcinoma vs. non-adenocarcinoma NEPC variants) is predictive of platinum sensitivity. Given that NEPC exists as a spectrum, there may be men with adenocarcinoma who might benefit from platinum chemotherapy, particularly those men with DNA repair defects.

METHODS

This was a retrospective study of all of the men seen at Duke University since 2005 who had metastatic castration-resistant prostate cancer (mCRPC) and were treated with a platinum agent. Data surrounding clinical features, histology, imaging, safety, and neuroendocrine transformation were collected. Scans were re-reviewed using RECIST v1.1 criteria to estimate responses as well as calculate radiographic progression-free survival (rPFS).

RESULTS

A database search identified 73 men with mCRPC treated with cisplatin, carboplatin, or oxaliplatin. There were three men with primary NEPC and small cell prostate cancer, and 14 with a NEPC transformation. In the first-line setting, 10 (63%) men with NEPC had a partial response (PR) compared with 14 (29%) of the men with adenocarcinoma (p = 0.017), with a median rPFS of 5.1 mo (3.1-7.8) and 4.3 mo (3.0-5.2 mo), respectively. The median overall survival was 8.5 mo (6.4-20.1 mo) for men with NEPC compared to 10.0 mo (8.0-14.4) in men with adenocarcinoma. Prostate-specific antigen (PSA) declines meeting >30%, >50%, and >90% criteria from baseline were observed in 64/57/29% of NEPC patients (n = 14) treated with platinum chemotherapy vs. 48/30/14% of men with prostate adenocarcinoma (n = 50), respectively.

CONCLUSIONS

This study suggests that NEPC histology enriches for platinum sensitivity, but that an important minority group (20-30%) of men with adenocarcinoma have a clinical benefit with platinum-based chemotherapy. Molecular predictors, such as germline or somatic mutations in DNA repair enzymes, should be evaluated for platinum responsiveness.

SEOM clinical guidelines for the treatment of metastatic prostate cancer (2017)

Androgen deprivation treatment was the only treatment available for metastatic prostate cancer until recently, with docetaxel as the only treatment with a proven survival benefit in castration-resistant prostate cancer (CRPC). Several drugs have been approved in the castration-resistant disease (sipuleucel-T, cabazitaxel, abiraterone, enzalutamide, radium-223). More recently, docetaxel and abiraterone have been moved to the hormone-sensitive disease setting, achieving better patient survival. The purpose of this article is to define the state of the art in the treatment of prostate carcinoma.