Co-mutations of KRAS/BRAF and TP53 or the high tumor mutation burden to predict survival in patients with biliary tract carcinoma.

Abstract

e16650 Background: Biliary tract carcinoma (BTC), including cholangiocarcinoma and gallbladder carcinoma, is the second most common type of hepatobiliary cancer. Patients with BTC always show poor prognosis, here we revealed the molecular landscape of BTC in the Chinese population and evaluated the role of different mutations in informing prognosis. Methods: Formalin-Fixed Paraffin-Embedded (FFPE) or freshly-sampled tumor tissues from 59 BTC patients were conducted next-generation sequencing of 620 genes related to oncogenesis. Tumor mutation burden (TMB) value represents the number of non-synonymous mutations per mega base pairs in each sample. Kaplan-Meier survival curves were generated and compared using the log-rank test. Results: Altogether, 59 patients have mutations mainly in TP53, Ras/Raf, PI3K, CDK signaling pathways and SWI/SNF complex. The most frequently mutated gene was TP53(53%), followed by KRAS(23%), ARID1A(17%), ATM(12%), CDKN2A(10%), SMAD4(8%), BRCA2(8%), STK11(7%), BRAF(5%), IDH1(5%) and FGFR3 (3%). Noticeably, only one patient with FGFR2 fusion was detected. The Median TMB of these patients is 2.80 Muts/Mbp (0-36.52 Muts/Mbp). Existing data showed that KRAS/BRAF alterations were associated with a worse overall survival (OS) (median OS 166d vs. 294d, p= 0.063). Further analysis indicated that RAS/BRAF mutations were often co-current with TP53 alternations. And patients with coaltered RAS/BRAF and TP53 demonstrated the worst prognosis (media OS 123d vs. 294d, p= 0.087). In addition, a higher TMB ( > 2.80 Muts/Mb) was also associated with a worse survival (median OS 174d vs. 355d, p= 0.085). Conclusions: We identified KRAS/BRAF, or co-mutations with TP53 and high TMB could predict poor prognosis in BTC patients. These findings will be useful for clinical decision making in patients with refractory biliary tract cancer and for risk stratification of patients in future clinical studies.