The genomic landscape of Chinese patients with upper tract urothelial carcinoma.

Abstract

e16583 Background: Upper tract urothelial carcinoma (UTUC) is known to have a distinct aggressive clinical phenotype and its genomic characterization is poorly understood, especially in Asian population. In this study, we aimed to characterize the genomic landscape of Chinese UTUC patients and explore the clinical relevance, which is the largest cohort of UTUC to date. Methods: Overall, 122 Chinese patients with UTUC were enrolled. Tumor and germline DNA from patients were analyzed using a targeted next-generation sequencing assay to identify somatic mutations in 520 cancer associated genes. Mutations like deletion, amplification and gene fusion were included. Tumor mutational burden (TMB) and microsatellite instability (MSI) status were also evaluated. The frequency of genomic alterations in patients with UTUC was compared with that of the Western counterpart from previous studies. Results: In total, 13 low-grade and 109 high-grade UTUC patients were included in this study. The most frequent genomic alterations were identified in genes like TERT (50.0%; 61.5% low-grade vs 48.6% high-grade), KMT2D (48.4%; 61.5% vs 46.8%), FGFR3 (41.0%; 69.2% vs 37.6%), TP53 (37.7%; 7.7% vs 41.3%), CDKN2A (22.1%; 23.1% vs 22.0%), KDM6A (20.5%; 15.4% vs 21.1%) with different mutation frequencies in the two subgroups of patients. Despite the overall similarity (including FGFR3, ARID1A and CDKN2A), the comparison between our cohort and the two Western UTUC cohorts (n = 119, 24 low-grade and 95 high-grade) revealed significant differences in mutation frequencies of KMT2D (48.4% vs 36.1%), TERT (50.0% vs 26.9%), TP53 (37.7% vs 21.9%) and KDM6A (20.5% vs 32.8%) . Chi-square analysis revealed that patients with history of other cancers (4/17 vs. 3/105, P = 0.001) were more likely to have a MSI-high status. In addition, females (9/44 vs. 6/78, P = 0.039) and patients with cancer history (6/17 vs. 9/105, P = 0.002) were more likely to have high TMB (≥20 mutations/Mb; median: 6.48 mutations/Mb). At last, the frequency of germline P/LP variants were also similar but different in the spectrum between our cohort and the Western UTUC population. Differences in mutation frequency of APC (0 vs 2.6%), BRAC2 (2.6% vs 0.9%), CHEK2 (0.3% vs 1.8%), MSH2 (2.6% vs 5.3%) and MSH6 (0 vs 1.8%) were significant. Conclusions: This study revealed that Chinese UTUC patients had a similar frequency of genomic alterations with western patients. However, there were significant differences in the prevalence of several mutated genes including KMT2D, TERT, TP53 and KDM6A, suggesting the ethnicity differences between the two populations. Our findings laid the foundation of a deeper understanding of UTUC biology and will provide potential targets for the development of precision therapies in UTUC.