Association between somatic mutation pathways and treatment response in patients with biliary tract cancers (BTCs).

Abstract

e16196 Background: Comprehensive somatic genomic profiling has become the standard of care for patients with BTCs, serving to identify targetable mutations and aiding in prognostication. While previous studies have identified individual somatic mutations such as TP53, CDKN1A, and KRAS as negative prognostic markers, little is known about their role as predictive biomarkers. This study aimed to investigate the predictive potential of somatic mutations and pathways using commercially available next-generation sequencing. Methods: We conducted a retrospective cohort study at Beth Israel Deaconess Medical Center (BIDMC) from January 2016 to January 2023, with data censoring in January 2024. Patient characteristics, including age, gender, race, stage, site of metastasis, performance status, and survival status, were collected. Somatic genomic alterations data were extracted from FoundationOneCDx, a commercially available NGS platform designed to capture 324 genetic alterations validated for therapy targets or unambiguous drivers of oncogenesis. Genetic alterations were classified into 14 oncogenic pathways constructed based on the TCGA and Reactome databases. Multivariate Cox proportional hazards regression analysis was performed between pathway alterations, progression-free survival and overall survival, accounting for selected covariates with p < 0.05 or potential known confounders. Results: Among 97 BTCs, 90 were successfully sequenced. Among these, 40 patients received gemcitabine and cisplatin, and 28 received fluorouracil and oxaliplatin (FOLFOX) therapy. Intrahepatic cholangiocarcinoma was present in 70% of cases, perihilar or distal cholangiocarcinoma in 27%, and gallbladder carcinoma in 3%. At presentation, 18% had stage I disease, and 44% had stage IV. The median follow-up time was 15 months. A total of 339 genomic alterations were identified, with 8% of samples harboring FGFR fusion or mutation, 9% IDH1 mutation, 6 % HER2 amplification, 30% KRAS mutation, and 32% with TP53 mutation. The most affected pathways were the cell cycle (66%) and DNA repair (50%). In multivariate regression analysis accounting for age, ECOG, and anatomical location, TP53 mutation was associated with shorter progression-free survival on gemcitabine and cisplatin treatment (n = 11, 2 vs. 6 months, HR 4.19, 95% CI 1.51 – 11.7, p < 0.01), whereas cell cycle pathway mutation was associated with longer progression-free survival (n = 14, 6 vs. 5 months, HR = 0.43, 95% CI 0.19-0.96, p < 0.05). No association was found between oncogenic pathways and treatment response to FOLFOX therapy. Conclusions: TP53 mutation is associated with a worse response, whereas cell cycle pathway mutations are associated with an improved response to gemcitabine and cisplatin therapy in patients with BTCs. Further research is needed to understand the mechanisms contributing to these observed effects.