Targeted Gene Sequencing of Gallbladder Carcinoma Identifies High-impact Somatic and Rare Germline Mutations

Abstract

Abstract. Background: Gallbladder carcinoma (GBC) isGallbladder carcinoma (GBC) is a type of biliary tract cancer, characterized by rapid progression and high mortality. Significant risk factors for GBC include presence of gallstones, chronic inflammation, anomalous pancreatobiliary ductal junctions, advancing age and female gender (1).Incidence and prevalence of GBC exhibit remarkable ethnic and geographical variability. This variability has been attributed to genetic predisposition and lifestyle habits or environmental exposure. The high incidence of GBC in the Indo-Gangetic belt and its poorly characterized molecular pathology have resulted in its reputation as an enigmatic Indian carcinoma (2). Until 2010, the genomic studies of GBC were limited to scanning a few common mutations in wellknown cancer-associated genes such as tumor protein p53 (TP53) and KRAS proto-oncogene, GTPase (KRAS) (3-5). Advancements in massively parallel sequencing technology, or next-generation sequencing (NGS), have propelled the area of cancer genomics and have greatly improved the understanding of tumorigenesis and tumor evolution linked with disease progression (6, 7). Application of NGS provides a means of high-throughput identification of cancer drivers and other genes that may be clinically relevant and or actionable for precision medicine (6). During the past decade, several large-scale cancer mutational landscape studies have contributed to the understanding of the existence of clonal variability within and across tumors in various common cancer types (8). However, GBC remains one of the understudied cancer types, with only a few studies on a limited number of samples (9-11). These studies and previous candidate gene-sequencing investigations indicate that GBC tumors from patients from different geographic regions may have different genetic architectures, suggesting the need for mutation exploration using a high-throughput NGS approach from varied populations (5, 12).The current treatment for patients with GBC is operative resection. However, resection is limited to cases that present at an early stage. GBCs which have progressed are largely incurable and the treatment mostly relies on focal radiation therapy and/or generic chemotherapy (12). The overall survival rate for patients with advanced GBC (stage 3 and 4) is very poor, and fewer than 10% survive for 5 years post 495 This article is freely accessible online.

Current and New Biomarkers for Early Detection, Prognostic Stratification, and Management of Gallbladder Cancer Patients

“…Those studies have shown that the most frequently altered genes in GBC are TP53, CDKN2A/B, ARID1A, ERBB2, and PI3KCA [113][114][115][116][117]. Some series have also reported KRAS [113,115] and SMAD4 [115,118] as commonly mutated genes in this neoplasia. Recently, Wardell et al investigated somatic and germline mutations in 412 BTCs from Japanese and Italian populations, which included 66 gallbladder or cystic duct cancers.…”

Novel Two MRT Cell Lines Established from Multiple Sites of a Synchronous MRT Patient

“…The definition of RTPS specifies the presence of multiple Rhabdoid tumors and molecular identification of a germline heterozygous pathogenic variant allele, either SNF5 or SMARCA4 (Brg-1) (13). Thus, it has been indicated that significant genes for tumor development exist not only in somatic mutatiosn but also in germline mutations (37). In our patient, a point-mutation in exon 2 of the SNF5 gene (c.157 C>T) was identified as a germline mutation.…”

A Novel Approach for the Genetic Analysis of Biliary Tract Cancer Specimens Obtained Through Endoscopic Ultrasound-Guided Fine Needle Aspiration Using Targeted Amplicon Sequencing

“…We achieved deep sequencing coverage and identified pathogenic alterations in 95.2% (20/21) of the patients with BTC using EUS-FNA samples. Previous reports on BTC showed equal or inferior success rates (47.5%, 92.1%, and 90.1%) (16–18) in identifying somatic alterations in BTC specimens obtained through surgical resection or ETB. With regard to using Hotspot Cancer Panel with pulmonary and pancreatic tissue specimens obtained through EUS-FNA, previous reports have shown 61.7%, 50%, and 100% success rates for the analysis of somatic alterations using TAS (10,19,20).…”