55P Integrative genomic analysis identified primary cilium-associated genes by as novel key genes in biliary tract cancer (BTC)

Abstract

Background: FGFR2 fusions and rearrangements occurring in 10e16% of patients with intrahepatic cholangiocarcinoma (ICC) reported in published scientific literature. Pemigatinib, a selective FGFR inhibitor, has demonstrated the high therapeutic potentials for ICC patients with FGFR2 fusions or rearrangements, according to the results of FIGHT 202 study. Whereas in Chinese population, the epidemiological data of FGFR2 fusions and rearrangements is still insufficient with limited sample sizes, and partner genes in FGFR2 fusion are still unknown.Methods: A total of 728 pathologically confirmed ICC samples (including surgical and biopsy samples from 728 patients aged over 18 years) were collected and tested FGFR2 fusion or rearrangement using fluorescence in situ hybridization (FISH) with break-apart probes. Thirty samples with known FGFR2 fusion or rearrangement were tested with next generation sequence (NGS) to identify the partner genes of FGFR2.Results: As of October 31, 2020, 728 patients were included and their samples were tested for FGFR2 gene fusion or rearrangement, 717 samples had readout. Forty-four samples (44/717, 6.14%) were tested FGFR2 gene fusion or rearrangement positive. Regionally, the highest positive rate (10.5%) was found in Southwest China (Sichuan and Yunnan province), and the lowest positive rate (5%) was in South China (Guangdong and Guangxi province). Twenty-six different FGFR2 fusion partner genes were identified in 30 samples, 22 (84.6%) of which were unique to individual patients. The most common partner was FGFR2-WAC (3/30, 10%).Conclusions: Based on a large sample size, the rate of FGFR2 gene fusion or rearrangement in Chinese ICC patients was 6.14%, and the FGFR2 partner genes were highly heterogeneous.Clinical trial identification: NCT04256980.