Integrative whole exome, transcriptome, and clinical profiling of biliary tract cancers (BTCs).

Abstract

279 Background: BTC is clinically and genomically heterogeneous and next generation sequencing may identify disease subsets with distinct prognostic and therapeutic implications. Methods: Patients (pts) with BTC underwent whole exome and transcriptome sequencing via the Michigan Oncology Sequencing (MI-ONCOSEQ) platform between 09/2011 and 07/2017. Results: 53 pts (47.2% female) with median age 60 (range 17-72) years had 38 intrahepatic, 6 perihilar, and 4 extrahepatic distal cholangiocarcinoma (CCA) while 3 had gallbladder and 2 mixed CCA/hepatocellular carcinoma. Forty-one pts (77.3%) had advanced BTC at diagnosis and 40 (75.5%) received platinum doublet as first line therapy. The most frequent somatic mutations were TP53 (35.8%), BAP1 (18.9%), KRAS (17.0%), IDH1 (15.1%), PBRM1 (13.2%), ARID1A (11.3%), and SMAD4 (11.3%). Median overall survival (OS) in 8 pts with IDH1 mutation was 16.8 months (none received IDH1 inhibitor). Putative pathogenic germline variants were noted in 6 (11.3%) pts of which 4 were biallelic (MSH2, BRCA1, BRCA2 and MUTYH) and 2 monoallelic (ATM and FH). Germline mutation in FH has not been reported in BTC. Biallelic DNA damage repair pathway mutations were noted in 14 (26.4%; 11 somatic, 3 germline) pts and their median OS was 16.8 months. Of these 9 pts with advanced BTC received 1st line platinum therapy and had a median PFS of 9.3 months (4 PR, 3 SD). Nine (17%) pts had FGFR2 fusion (6 partners); median OS not yet reached (6 alive; 5 received FGFR inhibitor). Potentially targetable molecular alterations (IDH1, MSH2, BRCA1/2, PALB2, ATM, FGFR2, ERBB2) were identified in 27 (50.9%) pts. Copy number profile shows frequent loss of chr1p, chr3p, chr4, chr6q, chr8p, chr9, and gain of chr1q, chr7, and chr8q. Immune profiling & pathway analysis of BTCs with clinical correlation is ongoing. Conclusions: Integrative sequencing of BTCs with clinical profiling will lead to more precise treatment of pts with BTCs.