Next generation sequencing:profiling gallbladder cancer (GBC)

Background: Molecular profiling data of GBC is scant and it is often included with other biliary cancers for analysis, which may hinder advancing drug discovery. Methods: Archival formalin fixed paraffin embedded (FFPE) tissue of GBC from 2 research hospitals in Toronto (n=21) and Hong Kong (n=21) were analyzed by MassARRAY Sequenom panel (23 genes, 279 mutations), or by next general sequencing (NGS) using Proton or Illumina MiSeq TruSeq Amplicon Cancer Panel (48 genes, 212 amplicons, ≥500x coverage). Results of other biliary cancer and ampullary cancer from an ongoing profiling project were also reported. Results: Twelve biliary cancer samples first analyzed with Sequenom revealed no mutations. Reanalysis with NGS of these yielded mutations in 5. All subsequent samples were analyzed with NGS (n=57). Mutations were identified in 80% [53 mutations in 42 GBC, 8 mutations in 9 intrahepatic cholangiocarcinoma (IHC), 7 mutations in 6 hilar/distal bile duct cancers (DBD)]. The most frequent mutations in GBC were TP53 and SMAD4, and KRAS mutation was found in 7% (Table). PIK3CA mutation was found in 5% of GBC but not the other biliary cancers, and IDH1 mutation was exclusive for IHC, in agreement with published literature. TP53 mutations in GBC patients did not correlate with gender, tumor grade, survival, or treatment response to gemcitabine-based chemotherapy. There was no difference in mutation patterns in GBC between 2 institutions/countries. Conclusions: NGS can be utilized for molecular profiling of biliary cancer, detecting potentially actionable targets in the majority of cases. Our preliminary data suggests GBC may have its own molecular profile, deserving special consideration in trial design for biliary cancer. To our knowledge the current study is the biggest cohort of NGS analysis for GBC. NGS analysis. Cancer site (frequency of mutation %) GBC (n=42) DBD (n=6) IHC (n=9) Ampulla (n=6*) TP53 71 83 22 67 SMAD4 10 0 0 0 KRAS 7 33 22 67 NRAS 0 0 11 0 BRAF 0 0 11 33 MLH1 5 0 0 0 CTNNB1 5 0 0 0 PIK3CA 5 0 0 0 IDH1 0 0 22 0 * Included 3 cases analyzed by Sequenom.