Genomic characterization and identification of actionable variants in patients with locally advanced or metastatic urothelial carcinoma (mUC).

Abstract

562 Background: Next generation sequencing (NGS)-based molecular profiling has been widely used across various tumor types including genitourinary malignancies to better understand and potentially predict tumor behavior. The goal of this study was to determine the feasibility of using NGS to characterize mUC and to identify potentially actionable variants. Methods: Patients with locally advanced or metastatic urothelial carcinoma (mUC) treated at the Princess Margaret Cancer Center were prospectively recruited for the OCTANE study, which collects archival tumor samples to provide genomic characterization through NGS with a custom hybridization capture DNA-based panel (555 genes) or a targeted DNA/RNA amplicon panel (Oncomine Comprehensive Assay v3, 161 driver gene panel). Variants were annotated using a somatic variant scheme [PMID: 25880439] or the oncoKB database. Comprehensive clinical information including patient, disease and treatment characteristics was collected using electronic patient records. Kaplan-Meier and cox regression were used for survival analysis. Results: Of the 73 patients, median age was 65 (23-83), majority were men (69%), most had lower tract disease (80%) and 41% had de novo metastatic disease. NGS was deemed feasible, based on availability of tumor samples, and performed in 67 (92%) patients. Overall, 61 (91%) had at least one oncogenic variant, including 34 (56%) with a potentially "druggable" target. The most frequent genomic alterations found were TP53 (44%), FGFR (18%), TERT (18%), ARID1A (18%) and PIK3CA (16%), all classified as "pathogenic/likely pathogenic". Only 2 patients received targeted treatment, one as part of clinical trial and one as standard of care. mOS was numerically longer among patients with genomic mutations compared to the ones without: 55 vs 31 months (HR: 0.87, CI 95% 0.3-2.4; p:0.7). No specific mutation was shown to significantly impact survival (table). Conclusions: Use of NGS technology in characterizing the genomic profile of patients with locally advanced or metastatic UC was feasible in most cases. Oncogenic variants were detected in the majority of patients, and more than half of them harbored a potentially "druggable" target, which may lead to future therapeutic advances.[Table: see text]