Genomic profiling of biliary tract carcinomas by their location.

Abstract

e16175 Background: Historically, biliary tract cancers have had a poor prognosis. Genomic profiling allows identification of alterations in genes with FDA-approved matched therapies either in these cancers ( FGFR2/3 fusions, certain IDH1 missense mutations), in all solid tumors (e.g. BRAF V600E mutations), or in other cancers (e.g. BRCA1/2 loss-of-function mutations) that could inform treatment. Here we examine the frequency of matched therapies in biliary tract carcinomas and the association with tumor location. Methods: All biliary tract carcinoma patient samples receiving the OncoExTra assay between April 2018 and November 2022 were included. The assay uses tumor-normal, whole-exome, whole-transcriptome sequencing to identify genomic alterations. Alterations in genes with FDA-approved matched therapies in any cancer, with matched clinical trials, or with evidence in cancer guidelines or the literature for possible matched therapies were recorded. Results: A total of 155 patient samples were processed: 92 intrahepatic CCA, 34 gall bladder carcinomas, 9 extrahepatic CCA, and 20 ampulla of Vater carcinomas. Targetable alterations were found in 153 (98.7%) samples; 31 (20.3%) had FDA-approved matched therapies, including 5 (3.3%) with microsatellite unstable and/or tumor mutational burden-high (eligible for immunotherapy) and 7 (4.6%) homologous recombinational repair deficient. Alterations of several genes showed a significant association with tumor type (Table). Cancers in the ampulla of Vater were enriched for KRAS, APC and ARID2 alterations; TP53 alterations were less frequent in biliary tract/intrahepatic cancers. Among the 15 FGFR1/2/3 alterations, there were 3 amplifications (1 FGFR1, 1 FGFR2, 1 FGFR3), 3 missense FGFR2 mutations, and 9 FGFR2 fusions. Conclusions: Comprehensive genomic profiling of biliary tract cancers identifies numerous targetable alterations. The distribution of altered genes varies, suggesting that appropriate therapies may differ by location, reflecting different lineage types. [Table: see text]