Intrahepatic Cholangiocarcinoma: Genomic Heterogeneity Between Eastern and Western Patients

Intrahepatic cholangiocarcinoma (IHCCA), a global health problem, is increasing in incidence and has differing etiologies worldwide. Next-generation sequencing (NGS) is rapidly being incorporated into the clinical management of biliary cancers. IHCCA is enriched with actionable mutations, and there are several promising targeted therapies under development. NGS data from Asia, where IHCCA is most prevalent, are limited.

Comprehensive genomic profiling of formalin-fixed paraffin-embedded tumor tissue from 164 Asian and 283 Western patients with IHCCA was performed using NGS. We measured the distribution of DNA repair genetic aberrations (GAs) in IHCCA, along with actionable mutations. Also, we evaluated the association between DNA repair GAs and tumor mutation burden (TMB). Based on the TMB status, patients were distinguished into 3 levels: low (< 6 mut/Mb), intermediate (6-10 mut/Mb), and high (TMB-H; ≥ 10 mut/Mb).

Seventy-two percent of Asian patients had ≥ 1 actionable GA, with a significantly higher frequency in KMT2C , BRCA1/2, and DDR2 compared with Western patients (P = .02, .003, and .003, respectively); 60.9% of Western patients had ≥ 1 actionable GA and higher frequency of CDKN2A/B and IDH1/2 GAs (P = .0004 and < .001, respectively). GAs in nuclear factor kappa B pathway regulators and DNA repair genes occurred more frequently in Asian patients (P = .006 and .001, respectively). There was a higher frequency of TMB-H in Asian compared with the Western cohort (12.2% v 5.9%; P = .07).

A higher burden of DNA repair mutations and frequency of patients with TMB-H in the Asian IHCCA cohort compared with the Western patients suggests a potential role for DNA repair and immune checkpoint inhibitors in the Asian population. Future clinical trials should account for this genetic heterogeneity.