Liquid Biopsy Analysis of FGFR3, TERT Promoter and STAG2 Hotspot Mutations for Disease Surveillance in Bladder Cancer

Patients with non-muscle invasive bladder cancer (NMIBC) are followed by frequent cystoscopies. Innovative approaches partly replacing cystoscopy (uncomfortable, expensive, low sensitive procedure) are demanded. The current study aims to establish a fast, reliable, non-invasive, and inexpensive procedure for NMIBC patient surveillance. Liquid biopsy is a reliable source of biomarkers for cancer patient monitoring. Urine is the most suitable biological liquid to search for bladder cancer biomarkers. Cell-free DNA in urine represents tumor-related mutations for several cancers, including the bladder. We investigated mutations in FGFR3, TERT promoter, and STAG2 as markers for diagnostics and follow-up in NMIBC. Digital PCR was used to detect mutations in urine-derived cell-free DNA. The sensitivity and specificity of the markers in relation to clinical outcomes served as criteria of the assay efficiency. The sensitivity with a single marker (TERT) reached 87%, with a specificity of 77%. Combining two biomarkers (TERT+FGFR3) increased the specificity of the assay to 100% with a sensitivity of 72%. Different mutational status of STAG2 can indicate NMIBC presence or recurrence. Therefore, applying the suggested combination of biomarkers with simple detection procedures to larger patient cohorts will allow developing procedures for BC detection and surveillance with optimal sensitivity and specificity. Based on the results of this proof-in-concept study, we conclude that this simple, fast and inexpensive assay can add diagnostic and prognostic value to cystoscopy/cytology analysis of NMIBC patients.