Characteristics of breast cancer patients tested for germline BRCA1/2 mutations by next-generation sequencing in Ramathibodi Hospital, Mahidol University

INTRODUCTION

Germline mutations in BRCA1/2 are the most common cause of hereditary breast and ovarian cancer (HBOC) syndrome. Few studies published during the past decade reported the prevalence of germline BRCA mutations in Asian patients with breast cancer. We aimed to assess the prevalence and characteristics of Thai patients with breast cancer with germline BRCA1/2 mutations.

METHODS

We retrospectively reviewed all breast cancer patients who were tested for germline BRCA1/2 mutations during 2014-2018. BRCA mutations were detected using next-generation sequencing and confirmed using Sanger sequencing. We analyzed the characteristics of patients with or without BRCA mutations. Disease-free survival (DFS) and the associated factors were determined.

RESULTS

Among 67 patients, 12 (18%) were BRCA1/2 carriers (6 each), 4 (6%) harbored variants of uncertain significance, and 51 (76%) were non-carriers. We discovered two novel BRCA2 frameshift mutations (c.2380delA and c.8855dupT). Mean ages at breast cancer diagnosis of BRCA1, BRCA2, and non-carriers were 39.8, 46.2, and 42.0 years, respectively. The 12 tumors of BRCA carriers were mainly the luminal-B subtype. Two of these tumors were HER2-positive luminal-B, and the triple-negative subtype was not detected. After adjusting for stages and luminal subtypes, BRCA carriers experienced worse 3-year DFS than non-carriers (81.5% vs. 90.3%, HR 2.04 [0.64-6.49], p = .229). The stage at diagnosis was the sole factor significantly associated with 3-year DFS (100%, 84.8%, and 72.7%; stages I, II, and III, respectively).

CONCLUSION

Thai patients with breast cancer with BRCA1/2 mutations were mainly the luminal-B subtypes with worse prognosis than those without mutations.

Molecular alterations, tumor microenvironment and clinical correlations in Thai cholangiocarcinoma patients

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Background: The systemic treatment option of unresectable and advanced cholangiocarcinoma (CCA) is limited. The mainstay of treatment is gemcitabine and 5-FU based chemotherapy. Recently, there is the role of promising immunotherapy in MSI-HI CCA. This research aims to study molecular alterations and tumor microenvironment in Thai CCA patients in order to explore the novel treatment and the clinical correlations. Methods: Thirty-six CCA patients in Ramathibodi Hospital between year of 2018 and 2020 with adequate tissue were enrolled. NGS by ThermoFisher (comprehensive panel) for molecular profile and immunohistochemistry (IHC) staining for tumor microenvironment protein expression (CD3, CD4, CD8, CD20, CD138, CD163, FOXP3), and PD-L1 were performed. Clinical data was retrieved from electronic medical record. Survival analysis, univariate and multivariate analysis were performed by Cox-regression analysis. Stata version 16.0 was used for statistical analysis. Results: Intrahepatic CCA was the most common type of CCA in our population (81%). The top 10 common mutations were TP53 (69%), KMT2D 58%), KMT2B (52%), ARID1A (50%), FAT1 (50%), NOTCH3 (44%), FANCA (42%), SMAD4 (42%), EPHA2 (39%), and ARID1B (39%). We also found the interesting targetable genes in our CCA patients, such as, KRAS (33%), MTOR (33%), HER2 (31%), EGFR (31%), FGFR2 (28%), BRCA2 (25%), PIK3CA (22%), NTRK1 (19%), BRCA1 (17%), NTRK3 (11%), and BRAF (8%). Three patients had ALK fusion gene, 1 patient had NTRK1 fusion and the other one had NTRK3 fusion gene. Twelve out of 36 patients (33%) had MSI-HI and 56% of patients had TMB ≥ 10 mutations/megabase. The clinical factors significantly correlated with poor overall survival (OS) were unresectable disease, stage IV, bilirubin > 1.2, and CEA ≥ 22.5. The NF1, MTOR, HER2 mutations, and FOXP3-negative in stromal cells were significantly associated with longer OS, whereas EGFR, APC, FGFR2, and BRCA1 mutations might correlated with better OS. Conclusions: Our study demonstrated the unique molecular profile of Thai CCA patients. We found high prevalence of MSI-HI and high TMB in our population, together with the promising potential of targetable genes for developing targeted therapy in the future. FOXP3 expression was probably one of potential predictive biomarker for immunotherapy. Larger cohort should be explored.