Abstract A025: Integrating genomic alterations and histopathological features for enhanced risk stratification in non-muscle invasive bladder cancer

Abstract Urothelial carcinoma is the most prevalent type of bladder cancer, where non-muscle invasive bladder cancer (NMIBC) accounts for about 75% of the initial diagnosis. Recognizing the limitations of current WHO04/16 grading and TNM staging systems, this study investigates genomic alterations, mitotic activity index (MAI) and immunohistochemical (IHC) markers CK20, p53, and CD25 to identify better prognostic biomarkers in NMIBC. In this retrospective population-based study of NMIBC patients (n=287), a targeted next-generation sequencing (NGS) panel analysis was performed using Oncomine™ Focus Assay on Ion GeneStudio S5 platform to identify genomic changes, including single nucleotide variations (SNVs) and copy number variations (CNVs) across 52 genes. The results revealed that the most frequent gene variants were identified in FGFR3 (n=183, 45%) and PIK3CA (n=98, 24%), while AKT1 (n=39, 20%), ERBB2 (n=24, 12%), MYCN (n=23, 12%) and CCND1 (n=22, 11%) were among the most amplified genes. Distinct genetic associations were observed among Ta, T1, low-grade (LG), and high-grade (HG) tumors. Ta tumors were significantly associated with FGFR3 and PIK3CA mutations, while T1 tumors were linked to ERBB2 mutations (p0. 001). Additionally, LG tumors were enriched with FGFR3 mutations, while HG tumors were significantly associated with FGFR1, CCND1, and ERBB2 mutations (p0. 001). In the analysis of tumor recurrence, patients with FGFR3 mutations had significantly shorter recurrence-free survival (RFS) (p=0. 033). Analysis of stage progression revealed a significant association between FGFR3 mutations and improved PFS (p0. 001), while MYC, ERBB2 (p0. 001), and MYCN (p=0. 011) were linked to shorter PFS. In gene set enrichment analysis, gene sets like PIK3CA and ERBB2 (p=0. 003), and PIK3CA and MYC (p=0. 005), were inversely associated with progression-free survival (PFS). In the multivariate Cox regression analysis, MAI was the strongest predictor for PFS (p0. 001). The study emphasizes the potential of combining genomic alterations with histopathological features for enhanced risk stratification in NMIBC patients. Citation Format: Melinda Lillesand, Vebjørn Kvikstad, Einar Gudlaugsson, Ivar Skaland, Aida Slewa Johannessen, Almaz Nigatu Tesfahun, Sigmund Vegard Sperstad, Emiel A. M. Janssen, Marie Austdal. Integrating genomic alterations and histopathological features for enhanced risk stratification in non-muscle invasive bladder cancer abstract. In: Proceedings of the AACR Special Conference on Bladder Cancer: Transforming the Field; 2024 May 17-20; Charlotte, NC. Philadelphia (PA): AACR; Clin Cancer Res 2024;30 (10Suppl): Abstract nr A025.