Incidental germline findings during molecular profiling of tumor tissues for precision oncology: molecular survey and methodological obstacles

Untapped Potential of Poly(ADP-Ribose) Polymerase Inhibitors: Lessons Learned From the Real-World Clinical Homologous Recombination Repair Mutation Testing

Background

Testing for homologous recombination deficiency (HRD) mutations is pivotal to assess individual risk, to proact preventive measures in healthy carriers and to tailor treatments for cancer patients. Increasing prominence of poly(ADP-ribose) polymerase (PARP) inhibitors with remarkable impact on molecular-selected patient survival across diverse nosologies, ingrains testing for BRCA genes and beyond in clinical practice. Nevertheless, testing strategies remain a question of debate. While several pathogenic BRCA1/2 gene variants have been described as founder pathogenic mutations frequently found in patients from Russia, other homologous recombination repair (HRR) genes have not been sufficiently explored. In this study, we present real-world data of routine HRR gene testing in Russia.

Methods

We evaluated clinical and sequencing data from cancer patients who had germline/somatic next-generation sequencing (NGS) HRR gene testing in Russia (BRCA1/2/ATM/CHEK2, or 15 HRR genes). The primary objectives of this study were to evaluate the frequency of BRCA1/2 and non-BRCA gene mutations in real-world unselected patients from Russia, and to determine whether testing beyond BRCA1/2 is feasible.

Results

Data of 2,032 patients were collected from February 2021 to February 2023. Most had breast (n = 715, 35.2%), ovarian (n = 259, 12.7%), pancreatic (n = 85, 4.2%), or prostate cancer (n = 58, 2.9%). We observed 586 variants of uncertain significance (VUS) and 372 deleterious variants (DVs) across 487 patients, with 17.6% HRR-mutation positivity. HRR testing identified 120 (11.8%) BRCA1/2-positive, and 172 (16.9%) HRR-positive patients. With 51 DVs identified in 242 formalin-fixed paraffin-embedded (FFPE), testing for variant origin clarification was required in one case (0.4%). Most BRCA1/2 germline variants were DV (121 DVs, 26 VUS); in non-BRCA1/2 genes, VUS were ubiquitous (53 DVs, 132 VUS). In silico prediction identified additional 4.9% HRR and 1.2% BRCA1/2/ATM/CHEK2 mutation patients.

Conclusions

Our study represents one of the first reports about the incidence of DV and VUS in HRR genes, including genes beyond BRCA1/2, identified in cancer patients from Russia, assessed by NGS. In silico predictions of the observed HRR gene variants suggest that non-BRCA gene testing is likely to result in higher frequency of patients who are candidates for PARP inhibitor therapy. Continuing sequencing efforts should clarify interpretation of frequently observed non-BRCA VUS.

Current status and issues related to secondary findings in the first public insurance covered tumor genomic profiling in Japan: multi-site questionnaire survey

In June 2019, the Japanese National Health Insurance (NHI) system introduced coverage for two types of tumor genomic profiling (TGP): FoundationOne^Ⓡ CDx (F1) and OncoGuide™ NCC OncoPanel System (NCCOP). TGP sometimes reveals germline variants that are potentially pathogenic as secondary findings (SFs). We conducted a questionnaire-based survey to find out the operational statuses of F1 and NCCOP at institutions where TGP was performed to elucidate issues related to SFs. Responses were received from 97 of 112 institutions (86.6%). As of May 31, 2020, 88 (90.7%) and 78 (80.4%) institutions started performing F1 and NCCOP, respectively. Since F1 only examines tumor samples, germline confirmatory testing is necessary to determine whether they are actually germline pathogenic variants (GPVs). When physicians are obtaining informed consent all but 2.3% of the patients requested SF disclosure. Conversely, when presumed germline pathogenic variants (PGPVs) were detected, 46.2% were not willing to receive confirmatory tests as they wanted to prioritize cancer treatment over SFs investigation, while only 23.3% underwent confirmatory tests. Problems in cancer genomic medicine reported by clinical genetics departments included short-staffing (n = 10), insufficient interdepartmental cooperation (n = 9), inconsistent understanding of genetics among healthcare professionals (n = 8), and low utilization rate of SFs due to lack of insurance coverage for confirmatory tests and post-test health checkups (n = 8). Solutions include; determining the appropriate timing to confirm patient intent on SF disclosure, covering confirmatory tests for PGPVs by the NHI, and establishing cooperation between the oncology and clinical genetics departments.