Real-world genetic testing patterns in metastatic castration-resistant prostate cancer

Practical Guidance on Establishing a Molecular Testing Pathway for Alterations in Homologous Recombination Repair Genes in Clinical Practice for Patients with Metastatic Prostate Cancer

CONTEXT

Prostate cancer is a molecularly heterogeneous disease that is amenable to diagnostic testing to identify patients potentially eligible for personalised treatments inform familial risk and provide relevant information about potential prognosis. Several guidelines support the integration of genomic testing in a shared decision-making framework so that both health care professionals (HCPs) and patients are involved in determining the best treatment approach.

OBJECTIVE

To review current guidelines on molecular diagnostic testing for homologous recombination repair (HRR) gene alterations in patients with metastatic prostate cancer, with the aim of providing practical considerations for effective guideline implementation and establishment of an appropriate pathway for molecular diagnostic testing.

EVIDENCE ACQUISITION

We undertook a nonsystematic narrative review of the literature using PubMed to identify current guidelines and recommendations on molecular diagnostic testing for BRCA and/or homologous recombination repair gene alterations (HRRm) in patients with prostate cancer. In addition, selected articles that included BRCA/HRRm testing in clinical trials in metastatic castration-resistant prostate cancer and real-world evidence were also evaluated. Websites for relevant societies were reviewed for molecular diagnostic guidelines not published on PubMed.

EVIDENCE SYNTHESIS

Our review of guidelines published by several international societies that include molecular testing in prostate cancer identified variations in molecular testing approaches. The review of testing approaches used in clinical trials and real-world settings also highlighted several aspects that require improvement. Therefore, we compiled practical guidance for establishing an appropriate BRCA/HRR mutation testing pathway.

CONCLUSIONS

While there are several challenges to molecular testing and interpretation of test results that require enhancement, a multidisciplinary team approach will empower HCPs and their institutions to improve on or initiate their own molecular testing pathways. This in turn will lead to improvements in management strategies for patients with metastatic prostate cancer, for whom better treatment outcomes is a significant unmet need.

PATIENT SUMMARY

Establishing a molecular testing pathway in clinical practice for patients with metastatic castration-resistant prostate cancer will lead to fairer and more equal access to personalised treatments. This should lead to better outcomes, particularly for patients whose disease has spread to other areas of the body.

Genetic Testing in Men With Metastatic Castration-Resistant Prostate Cancer

This cross-sectional study assesses homologous recombination repair mutation genetic testing and associated characteristics among men with metastatic castration-resistant prostate cancer (mCRPC).

Real-world prevalence of homologous recombination repair mutations in advanced prostate cancer: an analysis of two clinico-genomic databases

BACKGROUND

Homologous recombination repair mutation (HRRm) status may guide risk-stratification and treatment decisions, including polyadenosine diphosphate-ribose polymerase inhibitor use, in advanced prostate cancer. Although HRRm prevalence has been reported in single-institution studies or clinical trials, real-world HRRm prevalence in diverse populations is unknown. We describe HRRm in the clinical setting using two real-world clinicogenomic databases: the Flatiron Health and Foundation Medicine, Inc. Clinico-Genomic Database (CGDB), a national electronic health record-derived database, and the American Association for Cancer Research Project Genomics Evidence Neoplasia Information Exchange (GENIE).

METHODS

This cross-sectional analysis included 3757 individuals diagnosed with prostate cancer who had next generation sequencing (NGS) as standard of care. The CGDB included men with advanced/metastatic prostate cancer and genetic data included both germline and somatic pathogenic mutations. The GENIE analysis included men with prostate cancer whose received NGS as standard of care, but the data were filtered to include somatic mutations only. Due to key differences among databases, direct comparisons were not possible. Overall prevalence of HRRm was calculated and stratified by demographic and clinical characteristics.

RESULTS

HRRm prevalence (combined germline and somatic) in CGDB (n = 487) was 24.6% (95% CI 20.9-28.7%), with no major differences across demographic and disease characteristic subgroups. HRRm prevalence (somatic) in GENIE (n = 3270) was 11.0% (95% CI 10.0-12.1%), which varied between 9.5% and 18.4% across treatment centers.

CONCLUSIONS

Approximately one-quarter of patients with advanced/metastatic prostate cancer in the CGDB had germline and/or somatic HRRm, which is consistent with clinical trials such as the PROfound study that used a similar NGS platform and algorithm to define HRRm. In the GENIE database, HRRm prevalence varied by treatment center or NGS platform. More research is needed to understand real-world HRRm prevalence variations.

Efficacy of National Comprehensive Cancer Network Guidelines in Identifying Pathogenic Germline Variants Among Unselected Patients with Prostate Cancer: The PROCLAIM Trial

BACKGROUND

Prostate cancer (PCa) patients with pathogenic/likely pathogenic germline variants (PGVs) in cancer predisposition genes may be eligible for U.S. Food and Drug Administration-approved targeted therapies, clinical trials, or enhanced screening. Studies suggest that eligible patients are missing genetics-informed care due to restrictive testing criteria.

OBJECTIVE

To establish the prevalence of actionable PGVs among prospectively accrued, unselected PCa patients, stratified by their guideline eligibility.

DESIGN, SETTING, AND PARTICIPANTS

Consecutive, unselected PCa patients were enrolled at 15 sites in the USA from October 2019 to August 2021, and had multigene cancer panel testing.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Correlates between the prevalence of PGVs and clinician-reported demographic and clinical characteristics were examined.

RESULTS AND LIMITATIONS

Among 958 patients (median [quartiles] age at diagnosis 65 [60, 71] yr), 627 (65%) had low- or intermediate-risk disease (grade group 1, 2, or 3). A total of 77 PGVs in 17 genes were identified in 74 patients (7.7%, 95% confidence interval [CI] 6.2-9.6%). No significant difference was found in the prevalence of PGVs among patients who met the 2019 National Comprehensive Cancer Network Prostate criteria (8.8%, 43/486, 95% CI 6.6-12%) versus those who did not (6.6%, 31/472, 95% CI 4.6-9.2%; odds ratio 1.38, 95% CI 0.85-2.23), indicating that these criteria would miss 42% of patients (31/74, 95% CI 31-53%) with PGVs. The criteria were less effective at predicting PGVs in patients from under-represented populations. Most PGVs (81%, 60/74) were potentially clinically actionable. Limitations include the inability to stratify analyses based on individual ethnicity due to low numbers of non-White patients with PGVs.

CONCLUSIONS

Our results indicate that almost half of PCa patients with PGVs are missed by current testing guidelines. Comprehensive germline genetic testing should be offered to all patients with PCa.

PATIENT SUMMARY

One in 13 patients with prostate cancer carries an inherited variant that may be actionable for the patient's current care or prevention of future cancer, and could benefit from expanded testing criteria.

Tumor testing and treatment patterns in veterans with metastatic castration-resistant prostate cancer

INTRODUCTION

In 2016, the Department of Veterans Affairs (VA) and Prostate Cancer Foundation (PCF) began a partnership to improve access to testing. The primary objective of this analysis was to describe the use of tumor testing and treatment patterns in Veterans who progressed to metastatic castration-resistant prostate cancer (mCRPC) from 2016 to 2021. Secondary objectives including identifying factors associated with receipt of tumor testing, and reporting HRR mutation results among a subset who were tested.

METHODS AND MATERIALS

Natural language processing algorithms were applied to VA electronic health record data to identify a nationwide cohort of veterans with mCRPC. Tumor testing over time and by region were reported, alongside first-, second-, and third-line treatment patterns. Factors associated with receipt of tumor testing were identified using generalized linear mixed models with binomial distributions and logit links to account for clustering by VA facility.

RESULTS

Of the 9,852 veterans analyzed, 1,972 (20%) received tumor testing, with 73% of testing occurring in 2020-2021. Factors associated with tumor testing included younger age, later diagnosis year, being treated in the Midwest, or Puerto Rico or other compared to the South, and being treated at a PCF-VA Center of Excellence. Fifteen percent of tests were positive for a pathogenic HRR mutation. Seventy-six percent of the study cohort received first-line treatment, and among those, a subsequent 52% received second-line treatment. A subsequent 46% received third-line treatment.

CONCLUSION

After the VA-PCF partnership, one-fifth of veterans with mCRPC received tumor testing, with most tests occurring in 2020-2021.

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.

Comparison of Germline Genetic Testing Before and After a Medical Policy Covering Universal Testing Among Patients With Colorectal Cancer

IMPORTANCE

In 2020, some health insurance plans updated their medical policy to cover germline genetic testing for all patients diagnosed with colorectal cancer (CRC). Guidelines for universal tumor screening via microsatellite instability and/or immunohistochemistry (MSI/IHC) for mismatch repair protein expression for patients with CRC have been in place since 2009.

OBJECTIVES

To examine whether uptake of MSI/IHC screening and germline genetic testing in patients with CRC has improved under these policies and to identify actionable findings and management implications for patients referred for germline genetic testing.

DESIGN, SETTING, AND PARTICIPANTS

The multicenter, retrospective cohort study comprised 2 analyses of patients 18 years or older who were diagnosed with CRC between January 1, 2017, and December 31, 2020. The first analysis used an insurance claims data set to examine use of MSI/IHC screening and germline genetic testing for patients diagnosed with CRC between 2017 and 2020 and treated with systemic therapy. The second comprised patients with CRC who had germline genetic testing performed in 2020 that was billed under a universal testing policy.

MAIN OUTCOMES AND MEASURES

Patient demographic characteristics, clinical information, and use of MSI/IHC screening and germline genetic testing were analyzed.

RESULTS

For 9066 patients with newly diagnosed CRC (mean [SD] age, 64.2 [12.7] years; 4964 [54.8%] male), administrative claims data indicated that MSI/IHC was performed in 6645 eligible patients (73.3%) during the study period, with 2288 (25.2%) not receiving MSI/IHC despite being eligible for coverage. Analysis of a second cohort of 55 595 patients with CRC diagnosed in 2020 and covered by insurance found that only 1675 (3.0%) received germline genetic testing. In a subset of patients for whom germline genetic testing results were available, 1 in 6 patients had pathogenic or likely pathogenic variants, with most of these patients having variants with established clinical actionability.

CONCLUSIONS AND RELEVANCE

This nationwide cohort study found suboptimal rates of MSI/IHC screening and germline genetic testing uptake, resulting in clinically actionable genetic data being unavailable to patients diagnosed with CRC, despite universal eligibility. Effective strategies are required to address barriers to implementation of evidence-based universal testing policies that support precision treatment and optimal care management for patients with CRC.

Alignment of health plan coverage policies for somatic multigene panel testing with clinical guidelines in select solid tumors

Aim: Commercial plan coverage policies for multigene panel tests may vary and could result in geographic variation in coverage due to the fragmented nature of the commercial insurance market. This study aimed to characterize the alignment of multigene panel tests coverage policies to that of clinical guidelines, overall and by state. Materials & methods: We reviewed NCCN Guidelines^® for four tumors. Public coverage policies were identified via web search. Payer policies included those with the largest or second largest number of commercial lives in each state. Policies were classified as 'more restrictive' or 'consistent' with the guidelines. Results: Of 38 plans/policies reviewed, 71% were classified as 'more restrictive' than the guidelines, with variation in the number of commercial lives by state. Among these, 52% restricted on panel size and 63% restricted in all or select tumors. Conclusion: Most coverage policies were more restrictive. Clinical guideline clarity and state policies may improve alignment to guidelines and geographic variations.

Real-world homologous recombination repair mutation testing in metastatic castration-resistant prostate cancer in the USA, Europe and Japan

Aim: To assess homologous recombination repair mutation (HRRm) testing patterns in metastatic castration-resistant prostate cancer. Methods: A point-in-time, international survey conducted January–August 2020. Results: Three-quarters of physicians (oncologists, urologists, specialist surgeons) globally reported access to genetic/genomic testing and just over half were HRRm testers. Surveyed physicians reported HRRm testing and positivity rates for 1913 patients, which were 18.1% and 33.7%, respectively. Of patients tested (n = 347), the most common HRR genes tested were BRCA (91.6%) and ATM (47.3%). Conclusion: Overall testing rates were low, with physicians mostly testing patients they considered higher risk. Increased awareness and education are needed to encourage broader testing, to understand familial risk and to identify patients with worse outcomes or those eligible for life-prolonging treatments.

Genetics in prostate cancer: implications for clinical practice

PURPOSE OF REVIEW

Recent advances in our understanding of prostate cancer genetics have transformed the field. However, challenges in implementation and clinical application remain. The aim of this review is to discuss recent noteworthy publications in prostate cancer germline testing, genetically informed treatment, and polygenetic risk.

RECENT FINDINGS

The recent U.S. Food and Drug Administration approval of two poly adenosine diphosphate-ribose inhibitors (olaparib and rucaparib) for the treatment of men with metastatic castration-resistant prostate cancer with mutations in DNA damage repair genes and updates to the National Cancer Center Network testing guidelines that expand the eligibility criteria for germline and somatic genetic testing in men with prostate cancer provide an opportunity for a larger portion of the prostate cancer population to access genetic testing and targeted therapies. Due to this, clinicians have needed to rapidly adapt their clinical workflows. Further, the field has renewed efforts to evaluate polygenetic risk profiles to better understand the complex genetic landscape beyond single genes.

SUMMARY

This review highlights advances in the understanding of prostate cancer genetics, and areas that remain less well defined. Collaboration between multidisciplinary team members is necessary to move this field forward and provide quality, optimal care.