A systematic review and meta-analysis of germline BRCA mutations in pancreatic cancer patients identifies global and racial disparities in access to genetic testing

Clinical significance of germline breast cancer susceptibility gene (gBRCA) testing and olaparib as maintenance therapy for patients with pancreatic cancer

BACKGROUND

Germline breast cancer susceptibility gene (gBRCA) mutation in patients with pancreatic cancer (PC) is not common in clinical practice. Therefore, factors that efficiently show gBRCA mutations and the real-world outcomes of olaparib maintenance therapy have not been fully established. In the present study, we clarified the indicators for the effective detection of gBRCA mutation and the efficacy and safety of olaparib as maintenance therapy.

METHODS

We retrospectively analyzed 84 patients with PC who underwent gBRCA testing (BRACAnalysis, Myriad Genetics, Salt Lake City, UT, USA) at our institute between January 2021 and March 2022. For each patient, clinical data were extracted from medical records.

RESULTS

The median patient age was 64 y (29-85 y), and 41 patients (48.8%) were male. The gBRCA mutations were identified in 10 (11.9%) patients; two patients had BRCA1 mutation and eight had BRCA2 mutation. All patients with gBRCA mutation had a family history of any cancer, and eight of them had a family history of Hereditary Breast and Ovarian Cancer syndrome (HBOC)-related cancer. The gBRCA mutation rate was higher for patients with PC with a family history of HBOC-related cancer compared to that in patients with PC having a family history of other cancers and no family history of cancer (22.9% vs. 4.1%; P = 0.014). In our study, eight out of 10 patients with gBRCA-positive PC received olaparib after platinum-based chemotherapy. The best responses to platinum-based chemotherapy included a complete response in one patient (12.5%) and a partial response in seven patients (87.5%). The median duration of treatment with platinum-based chemotherapy plus olaparib was 17.5 months (8-87 months), and the duration of treatment with olaparib maintenance therapy was 11 months (1-30 months). During olaparib maintenance therapy, three patients showed no disease progression. One of these three patients underwent conversion surgery after receiving olaparib for 12 months.

CONCLUSIONS

The gBRCA testing should be considered proactively, especially in patients with PC with a family history of HBOC-related cancer.

Utilization and Outcomes of Multigene Panel Testing in Patients With Pancreatic Ductal Adenocarcinoma

PURPOSE

Guidelines recommend germline genetic testing (GT) for patients with pancreatic ductal adenocarcinoma (PDAC). This study aims to evaluate the utilization and outcomes of multigene panel GT in patients with PDAC.

METHODS

This retrospective, multisite study included patients with PDAC diagnosed between May 2018 and August 2020 at Mayo Clinic Arizona, Florida, and Minnesota. Discussion, uptake, and outcomes of GT were compared before (May 1, 2018-May 1, 2019) and after (August 1, 2019-August 1, 2020) the guideline update, accounting for a transition period.

RESULTS

The study identified 533 patients with PDAC, with 321 (60.2%) preguideline and 212 (39.8%) postguideline. Patient characteristics did not differ between the preguideline and postguideline periods. GT was discussed in 34.3% (110 of 321) of preguideline and 39.6% (84 of 212) of postguideline patients (odds ratio [OR], 1.26 [95% CI, 0.88 to 1.80]) and subsequently performed in 80.9% (89 of 110) of preguideline and 75.0% (63 of 84) of postguideline patients (OR, 1.10 [95% CI, 0.75 to 1.61]). Of 152 tested patients, 26 (17.1%) had a pathogenic variant (PV), of whom 17 (11.2%; 17 of 152) were PDAC-associated. Over the entire study period, GT was more likely in younger patients (65 v 70 years; P < .001), those seen by a medical oncologist (82.9% v 69.0%; P < .001), and those surviving more than 12 months from diagnosis (70.4% v 43.4%; P < .001). Demographics and personal/family cancer history were comparable between patients with and without a PDAC PV.

CONCLUSION

GT remains underutilized despite National Comprehensive Cancer Network guideline recommendations. Given the poor prognosis of PDAC and potential implications of GT, efforts to increase utilization are needed to provide surveillance and support to both patients with PDAC and at-risk family members.

Improving Access to Hereditary Testing in Pancreatic Ductal Carcinoma

PURPOSE

Approximately 5%-10% of patients with pancreatic ductal adenocarcinoma (PDAC) have an inherited basis, yet uptake of genetic testing remains low and subject to disparities. This study compared two genetic testing pathways available to patients referred to a provincial cancer center, BC Cancer: a traditional hereditary cancer clinic-initiated testing (HCT) pathway and a new oncology clinic-initiated testing (OCT) pathway.

METHODS

Study subjects were patients with confirmed PDAC referred for genetic testing through the HCT or OCT pathway between June 1, 2020, and February 1, 2022. Charts were retrospectively reviewed for patient characteristics and testing outcomes.

RESULTS

The study population was 397 patients (HCT, n = 279 and OCT, n = 118). OCT patients were more likely to have non-European ethnicity compared with HCT patients (41.9% v 25.6%, P = .004), to have earlier-stage disease (P = .012), and to have better Eastern Cooperative Oncology Group performance status than the HCT group (P = .001). A total of 306 patients completed testing (77%). OCT patients had higher test completion rates than HCT patients (odds ratio, 3.74 [95% CI, 1.66 to 9.62]). Median time for results was shorter in OCT than in HCT (53 days [IQR, 44-76] v 107 days [IQR, 63.8-158.3]). Pancreatic cancer susceptibility pathogenic gene variants were identified in 8.5% (26/306).

CONCLUSION

The real-world observations in our study show that oncology clinic-initiated hereditary testing is more effective and faster than testing through hereditary cancer clinic referrals and reaches a more ethnically diverse population. This has important implications for publicly funded environments with limited resources for genetic counseling.

Selection of Germline Genetic Testing Panels in Patients With Cancer: ASCO Guideline

PURPOSE

To guide use of multigene panels for germline genetic testing for patients with cancer.

METHODS

An ASCO Expert Panel convened to develop recommendations on the basis of a systematic review of guidelines, consensus statements, and studies of germline and somatic genetic testing.

RESULTS

Fifty-two guidelines and consensus statements met eligibility criteria for the primary search; 14 studies were identified for Clinical Question 4.

RECOMMENDATIONS

Patients should have a family history taken and recorded that includes details of cancers in first- and second-degree relatives and the patient's ethnicity. When more than one gene is relevant based on personal and/or family history, multigene panel testing should be offered. When considering what genes to include in the panel, the minimal panel should include the more strongly recommended genes from Table 1 and may include those less strongly recommended. A broader panel may be ordered when the potential benefits are clearly identified, and the potential harms from uncertain results should be mitigated. Patients who meet criteria for germline genetic testing should be offered germline testing regardless of results from tumor testing. Patients who would not normally be offered germline genetic testing based on personal and/or family history criteria but who have a pathogenic or likely pathogenic variant identified by tumor testing in a gene listed in Table 2 under the outlined circumstances should be offered germline testing.Additional information is available at www.asco.org/molecular-testing-and-biomarkers-guidelines.

Disparate Rates of Germline Variants in Cancer Predisposition Genes in African American/Black Compared With Non-Hispanic White Individuals Between 2015 and 2022

PURPOSE

African American/Black (AA/B) individuals are under-represented in genomic databases and thus less likely to receive definitive information from germline genetic testing (GGT) than non-Hispanic White (NHW) individuals. With nearly 500,000 AA/B and NHW individuals having undergone multigene panel testing (MGPT) for hereditary cancer risk at a single commercial laboratory, to our knowledge, we present the largest study to date investigating cancer GGT results in AA/B and NHW individuals.

METHODS

MGPT results from a retrospective cohort of AA/B (n = 48,684) and NHW (n = 444,831) patients were evaluated. Frequencies of pathogenic germline variants (PGVs) and variants of uncertain significance (VUS) were compared between AA/B and NHW individuals. Changes in frequency of VUS over time were determined. Pearson's chi-squared test was used to compare categorical variables among groups. All significance tests were two-tailed, and P < .05 was considered statistically significant.

RESULTS

Between 2015 and 2022, rates of VUS decreased 2.3-fold in AA/B and 1.8-fold in NHW individuals; however, frequencies of VUS and PGV remained significantly higher (46% v 32%; P < .0001) and lower (9% v 13%; P < .0001) in AA/B compared with NHW individuals. Rates of VUS in ATM, BRCA1, BRCA2, PALB2, and PMS2 were significantly higher in AA/B compared with NHW individuals, whereas rates of PGV in BRCA1, BRCA2, and PALB2 were higher in AA/B compared with NHW individuals (P < .001).

CONCLUSION

Despite reductions in VUS frequencies over time, disparities in definitive GGT results persist. Increasing inclusion of AA/B populations in both testing and research will further increase knowledge of genetic variants across these racial groups.

Combination of mutations in genes controlling DNA repair and high mutational load plays a prognostic role in pancreatic ductal adenocarcinoma (PDAC): a retrospective real-life study in Sardinian population

BACKGROUND

Patients with pancreatic ductal adenocarcinoma (PDCA) carrying impaired mismatch repair mechanisms seem to have an outcome advantage under treatment with conventional chemotherapy, whereas the role for the tumor mutation burden on prognosis is controversial. In this study, we evaluated the prognostic role of the mutated genes involved in genome damage repair in a real-life series of PDAC patients in a hospital-based manner from the main Institution deputed to surgically treat such a disease in North Sardinia.

METHODS

A cohort of fifty-five consecutive PDAC patients with potentially resectable/border line resectable PDAC (stage IIB-III) or oligometastatic disease (stage IV) and tumor tissue availability underwent next-generation sequencing (NGS)-based analysis using a panel containing driver oncogenes and tumor suppressor genes as well as genes controlling DNA repair mechanisms.

RESULTS

Genes involved in the both genome damage repair (DR) and DNA mismatch repair (MMR) were found mutated in 17 (31%) and 15 (27%) cases, respectively. One fourth of PDAC cases (14/55; 25.5%) carried tumors presenting a combination of mutations in repair genes (DR and MMR) and the highest mutation load rates (MLR-H). After correction for confounders (surgery, adjuvant therapy, stage T, and metastasis), multivariate Cox regression analysis indicated that mutations in DR genes (HR = 3.0126, 95% CI 1.0707 to 8.4764, p = 0.0367) and the MLR (HR = 1.0018, 95%CI 1.0005 to 1.0032, p = 0.009) were significantly related to worse survival.

CONCLUSIONS

The combination of mutated repair genes and MLR-H, which is associated with a worse survival in our series of PDAC patients treated with conventional chemotherapy protocols, might become a predictive biomarker of response to immunotherapy in addition to its prognostic role in predicting survival.

Germline BRCA testing in pancreatic cancer: improving awareness, timing, turnaround, and uptake

Prognosis is generally poor for patients with pancreatic ductal adenocarcinoma. However, patients with germline BRCA1 or BRCA2 mutations (gBRCAm) may benefit from first-line platinum-based chemotherapy and maintenance therapy with the poly(adenosine diphosphate-ribose) polymerase inhibitor olaparib following at least 16 weeks of first-line platinum-based chemotherapy without disease progression. Germline breast cancer gene (BRCA) testing is therefore important to ensure that patients receive the most effective treatment. In addition, testing for other DNA damage response gene mutations beyond gBRCAm may also guide treatment decisions. However, clinical pathways for genetic testing are often suboptimal, leading to delays in treatment initiation or missed opportunities for personalized therapy. Barriers to testing include low rates of referral and uptake, delays to referral and slow result turnaround times, cost, and biopsy and assay limitations if somatic testing is performed, leading to the requirement for subsequent dedicated germline testing. Low rates of referral may result from lack of awareness among physicians of the clinical value of testing, coupled with low confidence in interpreting test results and poor availability of genetic counseling services. Among patients, barriers to uptake may include similar lack of awareness of the clinical value of testing, anxiety regarding the implications of test results, lack of insurance coverage, fear of negative insurance implications, and socioeconomic factors. Potential solutions include innovative approaches to testing pathways, including 'mainstreaming' of testing in which BRCA tests are routinely arranged by the treating oncologist, with the involvement of genetic counselors if a patient is found to have a gBRCAm. More recently, the utility of multigene panel analyses has also been explored. Access to genetic counseling may also be improved through initiatives such as having a genetic counseling appointment for all new patient visits and telemedicine approaches, including the use of telephone consultations or DVD-assisted counseling. Educational programs will also be beneficial, and cost effectiveness is likely to improve as the number of targeted treatments increases and when the earlier detection of tumors in family members following cascade testing is considered.

Racial, Ethnic, and Sex-based Disparities among High-risk Individuals Undergoing Pancreatic Cancer Surveillance

Since its inception two years ago, the international, multicenter Pancreatic Cancer Early Detection (PRECEDE) Consortium has enrolled high-risk individuals (HRI) undergoing pancreatic ductal adenocarcinoma (PDAC) surveillance. Herein we aim to evaluate enrollment disparities in PRECEDE. Data on HRIs enrolled between May 2020 and March 2022 were collected, with HRIs defined as participants enrolled in PRECEDE meeting guideline-based criteria for PDAC surveillance. Of 1,273 HRIs enrolled, 1,113 were eligible for inclusion, with 47.2% meeting familial pancreatic cancer criteria without a known pathogenic variant (PV) and the remainder having a pathogenic variant in a PDAC-risk gene (CDKN2A, STK11, PRSS1, BRCA1, BRCA2, PALB2, ATM, MLH1, MSH2, MSH6, PMS2, or EPCAM). Study participants were predominantly from the United States (82.7%), the most common age range at enrollment was 60-69 years (37.4%), and a non-PDAC cancer was present in 32.4%. There were racial/ethnic- and sex-based disparities among enrolled subjects, as the majority of participants were female (65.9%) and self-reported white (87.7%), with only 2.9% having Hispanic ethnicity. While more than 97% of participants consented to utilize imaging data and biosamples for research, there was no difference in rate of consent based on race/ethnicity, sex, or age, thereby demonstrating uniform participation in research activities among all subgroups after enrollment. Ensuring that diversity of HRIs in PDAC surveillance programs mirrors the communities served by participating centers is important. Substantial racial/ethnic- and sex-based disparities persist among recently enrolled HRIs undergoing PDAC surveillance, and therefore reducing these disparities will be a major focus of the PRECEDE Consortium moving forward.

PREVENTION RELEVANCE

Pancreatic cancer surveillance is critical to decreasing pancreatic cancer mortality; therefore, it is important that pancreatic cancer surveillance studies enroll diverse patients. We demonstrate that substantial racial/ethnic- and sex-based disparities exist amongst enrollment in the international PRECEDE consortium, highlighting the dire need for future efforts to reduce these disparities. See related Spotlight, p. 305.