Whole-genome sequencing of 20 cholangiocarcinoma cases reveals unique profiles in patients with cirrhosis and primary sclerosing cholangitis.

BACKGROUND

Cholangiocarcinoma (CCA) is a molecularly heterogenous disease that is often fatal. Whole genome sequencing (WGS) can provide additional knowledge of mutational spectra compared with panel sequencing. We describe the molecular landscape of CCA using whole-genome sequencing and compare the mutational landscape between short-term and long-term survivors.

METHODS

We explored molecular differences between short-term and long-term survivors by performing WGS on 20 patient samples from our biliary tract cancer database. Short-term survivors were enriched for cases with underlying primary sclerosing cholangitis (PSC) and patients with cirrhosis. All samples underwent tumour epithelial enrichment using laser capture microdissection (LCM).

RESULTS

Dominant single base substitution (SBS) signatures across the cohort included SBS1 and SBS5, with the latter more prevalent in long-term survivors. SBS17 was evident in 3 cases, all of whom had underlying ulcerative colitis (UC) with PSC. Additional rare signatures included SBS3 in a patient treated for prior mantle cell lymphoma and SBS26/SBS6 in a patient with a tumor mutational burden of 33 mutations/Mb and a pathogenic germline mutation. Somatic inactivating mutations were present in 8/10 (80%) short-term survivors and in none of the long-term survivors. Additional mutations occurred in , and chromatin remodelling genes. The long-term survivor group harboured predicted fusions in (n=2) and pathogenic mutations in and (n=2).

CONCLUSIONS

alterations are associated with poor outcomes in patients with CCA. Patients with underlying inflammatory/autoimmune conditions may be enriched for unique tumour mutational signatures.