Risk Prediction Tools Available for Germline BRCA1/2 Mutations Underperform in Prostate Cancer Patients

BRCA1, BRCA2, and Associated Cancer Risks and Management for Male Patients: A Review

Importance

Half of all carriers of inherited cancer-predisposing variants in BRCA1 and BRCA2 are male, but the implications for their health are underrecognized compared to female individuals. Germline variants in BRCA1 and BRCA2 (also known as pathogenic or likely pathogenic variants, referred to here as BRCA1/2 PVs) are well known to significantly increase the risk of breast and ovarian cancers in female carriers, and knowledge of BRCA1/2 PVs informs established cancer screening and options for risk reduction. While risks to male carriers of BRCA1/2 PVs are less characterized, there is convincing evidence of increased risk for prostate cancer, pancreatic cancer, and breast cancer in males. There has also been a rapid expansion of US Food and Drug Administration-approved targeted cancer therapies, including poly ADP ribose polymerase (PARP) inhibitors, for breast, pancreatic, and prostate cancers associated with BRCA1/2 PVs.

Observations

This narrative review summarized the data that inform cancer risks, targeted cancer therapy options, and guidelines for early cancer detection. It also highlighted areas of emerging research and clinical trial opportunities for male BRCA1/2 PV carriers. These developments, along with the continued relevance to family cancer risk and reproductive options, have informed changes to guideline recommendations for genetic testing and strengthened the case for increased genetic testing for males.

Conclusions and Relevance

Despite increasing clinical actionability for male carriers of BRCA1/2 PVs, far fewer males than female individuals undergo cancer genetic testing. Oncologists, internists, and primary care clinicians should be vigilant about offering appropriate genetic testing to males. Identifying more male carriers of BRCA1/2 PVs will maximize opportunities for cancer early detection, targeted risk management, and cancer treatment for males, along with facilitating opportunities for risk reduction and prevention in their family members, thereby decreasing the burden of hereditary cancer.

The 5-WS of targeting DNA-damage repair (DDR) pathways in prostate cancer

DNA-damage repair (DDR) pathways alterations, a growing area of interest in oncology, are detected in about 20% of patient with prostate cancer and are associated with improved sensitivity to poly(ADP ribose) polymerases (PARP) inhibitors. In May 2020, the Food and Drug Administration (FDA) approved two PARP inhibitors (olaparib and rucaparib) for prostate cancer treatment. Moreover, germline aberrations in DDR pathways genes have also been related to familial or hereditary prostate cancer, requiring tailored health-care programs. These emerging scenarios are rapidly changing diagnostic, prognostic and therapeutic approaches in prostate cancer management. The aim of this review is to highlight the five W-points of DDR pathways in prostate cancer: why targeting DDR pathways in prostate cancer; what we should test for genomic profiling in prostate cancer; "where" testing genetic assessment in prostate cancer (germline or somatic, solid or liquid biopsy); when genetic testing is appropriate in prostate cancer; who could get benefit from PARP inhibitors; how improve patients outcome with combinations strategies.

Lineage Plasticity and Stemness Phenotypes in Prostate Cancer: Harnessing the Power of Integrated "Omics" Approaches to Explore Measurable Metrics

Prostate cancer (PCa), the most frequent and second most lethal cancer type in men in developed countries, is a highly heterogeneous disease. PCa heterogeneity, therapy resistance, stemness, and lethal progression have been attributed to lineage plasticity, which refers to the ability of neoplastic cells to undergo phenotypic changes under microenvironmental pressures by switching between developmental cell states. What remains to be elucidated is how to identify measurements of lineage plasticity, how to implement them to inform preclinical and clinical research, and, further, how to classify patients and inform therapeutic strategies in the clinic. Recent research has highlighted the crucial role of next-generation sequencing technologies in identifying potential biomarkers associated with lineage plasticity. Here, we review the genomic, transcriptomic, and epigenetic events that have been described in PCa and highlight those with significance for lineage plasticity. We further focus on their relevance in PCa research and their benefits in PCa patient classification. Finally, we explore ways in which bioinformatic analyses can be used to determine lineage plasticity based on large omics analyses and algorithms that can shed light on upstream and downstream events. Most importantly, an integrated multiomics approach may soon allow for the identification of a lineage plasticity signature, which would revolutionize the molecular classification of PCa patients.

Clinical implications of homologous recombination repair mutations in prostate cancer

Prostate cancer is a disease with significant interpatient genomics, with a proportion of patients presenting mutations in key homologous recombination repair (HRR) gene aberrations, particularly in late-stage disease. A better understanding of the genomic landscape of prostate cancer and the prognostic and predictive value of HRR mutations could lead to more precise care for prostate cancer patients. BRCA1/2 mutations are associated with a more aggressive disease course and higher risk of developing lethal prostate cancer, but also identify patients who could benefit from directed therapeutic strategies with PARP inhibitors. Other HRR mutations are also frequent but their prognostic and predictive value for prostate cancer patients is less clear. Moreover, a proportion of these mutations are associated with inherited germline defects, being relevant for the patients' risk of second malignancies but also to inform their relatives' risk of cancer through cascade testing. In this manuscript, we review current knowledge of the prognostic and predictive value for different HHR alterations across the different prostate cancer disease states. Additionally, we assess the challenges to implement genomic testing in clinical practice for prostate cancer patients.

DNA damage repair gene mutation testing and genetic counseling in men with/without prostate cancer: a systematic review

Background: Ongoing clinical trials are investigating PARP inhibitors to target the DNA damage repair (DDR) pathway in prostate cancer. DDR mutation screening will guide treatment strategy and assess eligibility for clinical trials. Materials & methods: This systematic review estimated the rate of DDR mutation testing or genetic counseling among men with or at risk of prostate cancer. Results: From 6856 records, one study fulfilled the inclusion criteria and described men undiagnosed with prostate cancer with a family history of BRCA1/2 mutation who received DDR mutation testing. Conclusion: With only one study included in this first systematic review of DDR mutation testing or genetic counseling in men with or at risk of prostate cancer, more research is warranted.

Genetic aberrations in DNA repair pathways: a cornerstone of precision oncology in prostate cancer

Over the past years, several studies have demonstrated that defects in DNA damage response and repair (DDR) genes are present in a significant proportion of patients with prostate cancer. These alterations, particularly mutations in BRCA2, are known to be associated with an increased risk of developing prostate cancer and more aggressive forms of the disease. There is growing evidence that certain DDR gene aberrations confer sensitivity to poly-(ADP ribose) polymerase inhibitors and/or platinum chemotherapy, while other defects might identify cases that are more likely to benefit from immune checkpoint inhibition. The potential prognostic impact and relevance for treatment selection together with the decreasing costs and broader accessibility to next-generation sequencing have already resulted in the increased frequency of genetic profiling of prostate tumours. Remarkably, almost half of all DDR genetic defects can occur in the germline, and prostate cancer patients identified as mutation carriers, as well as their families, will require appropriate genetic counselling. In this review, we summarise the current knowledge regarding the biology and clinical implications of DDR defects in prostate cancer, and outline how this evidence is prompting a change in the treatment landscape of the disease.

Performance of Three Inherited Risk Measures for Predicting Prostate Cancer Incidence and Mortality: A Population-based Prospective Analysis

BACKGROUND

Single nucleotide polymorphism-based genetic risk score (GRS) has been developed and validated for prostate cancer (PCa) risk assessment. As GRS is population standardized, its value can be interpreted as a relative risk to the general population.

OBJECTIVE

To compare the performance of GRS with two guideline-recommended inherited risk measures, family history (FH) and rare pathogenic mutations (RPMs), for predicting PCa incidence and mortality.

DESIGN, SETTING, AND PARTICIPANTS

A prospective cohort was derived from the UK Biobank where 208 685 PCa diagnosis-free participants at recruitment were followed via the UK cancer and death registries.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Rate ratios (RRs) of PCa incidence and mortality for FH (positive vs negative), RPMs (carriers vs noncarriers), and GRS (top vs bottom quartile) were measured.

RESULTS AND LIMITATIONS

After a median follow-up of 9.67 yr, 6890 incident PCa cases (419 died of PCa) were identified. Each of the three measures was significantly associated with PCa incidence in univariate analyses; RR (95 % confidence interval [CI]) values were 1.88 (1.75-2.01) for FH, 2.89 (1.89-4.25) for RPMs, and 1.97(1.87-2.07) for GRS (all p < 0.001). The associations were independent in multivariable analyses. While FH and RPMs identified 11 % of men at higher PCa risk, addition of GRS identified an additional 22 % of men at higher PCa risk, and increases in C-statistic from 0.58 to 0.67 for differentiating incidence (p < 0.001) and from 0.65 to 0.71 for differentiating mortality (p = 0.002). Limitations were a small number of minority patients and short mortality follow-up.

CONCLUSIONS

This population-based prospective study suggests that GRS complements two guideline-recommended inherited risk measures (FH and RPMs) for stratifying the risk of PCa incidence and mortality.

PATIENT SUMMARY

In a large population-based prostate cancer (PCa) prospective study derived from UK Biobank, genetic risk score (GRS) complements two guideline-recommended inherited risk measures (family history and rare pathogenic mutations) in predicting PCa incidence and mortality. These results provide critical data for including GRS in PCa risk assessment.

Rare Germline Pathogenic Mutations of DNA Repair Genes Are Most Strongly Associated with Grade Group 5 Prostate Cancer

BACKGROUND

Rare germline mutations in several genes, primarily DNA repair genes, have been proposed to predict worse prognosis of prostate cancer (PCa).

OBJECTIVE

To compare the frequency of germline pathogenic mutations in commonly assayed PCa genes between high- and low-grade PCa in patients initially presenting with clinically localized disease.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective case-case study of 1694 PCa patients who underwent radical prostatectomy at Johns Hopkins Hospital, including 706 patients with high-grade (grade group [GG] 4 and GG5) and 988 patients with low-grade (GG1) disease. Germline DNA was sequenced for 13 candidate PCa genes using a targeted next-generation sequencing assay by Ambry Genetics.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Carrier rates of pathogenic mutations were compared between high- and low-grade PCa patients using the Fisher's exact test.

RESULTS AND LIMITATIONS

Overall, the carrier rate of germline pathogenic mutations in the 13 genes was significantly higher in high-grade patients (8.64%) than in low-grade patients (3.54%, p = 9.98 × 10^-6). Individually, significantly higher carrier rates for patients with high- versus low-grade PCa were found for three genes: ATM (2.12% and 0.20%, respectively, p = 9.35 × 10^-5), BRCA2 (2.55% and 0.20%, respectively, p = 8.99 × 10^-6), and MSH2 (0.57% and 0%, respectively, p = 0.03). The mutation carrier rate was significantly higher in patients with GG5 than in patients with GG1 disease for the 13 genes overall (13.07% and 3.54%, respectively, p = 1.27 × 10^-9); for the three genes ATM, BRCA2, and MSH2 (7.73% and 0.40%, respectively, p = 3.20 × 10^-13); and for the remaining nine DNA repair genes (5.07% and 2.43%, respectively, p = 0.02).

CONCLUSIONS

In men undergoing treatment for clinically localized disease, pathogenic mutations in 13 commonly assayed genes, especially ATM, BRCA2, and MSH2, are most strongly associated with GG5 PCa. These findings emphasize the importance of genetic testing in men with high-grade PCa, particularly GG5 disease, to inform both treatment decisions and familial risk assessment.

PATIENT SUMMARY

Prostate cancer in men with inherited mutations in 13 commonly assayed susceptibility genes is more likely to be high-grade, high-risk disease.