Longitudinal circulating tumour DNA identifies patients at high risk of upstaging and recurrence in non-muscle-invasive bladder cancer.

Abstract

To evaluate whether longitudinal tumour-informed circulating tumour DNA (ctDNA) testing identifies patients at increased risk of upstaging and recurrence in high-risk non-muscle-invasive bladder cancer (NMIBC). A cohort of 52 patients with high-risk NMIBC underwent serial plasma ctDNA testing using a personalised tumour-informed assay. The ctDNA was obtained at initial presentation and at approximately 3-month surveillance intervals during appropriate routine clinical NMIBC therapy and follow-up. A subset of tumours underwent tumour-normal whole-exome sequencing to evaluate genomic alterations associated with ctDNA detection and clinical progression. Circulating tumour DNA was detectable in 17 of 52 patients (33%), including eight of 29 who were Bacillus Calmette-Guérin (BCG)-naïve (28%) and nine of 23 who were BCG-exposed/BCG-unresponsive patients (39%). Most patients received intravesical therapy, including BCG or salvage intravesical chemotherapy, and a subset underwent radical cystectomy. Clinical upstaging occurred in 10 of 17 ctDNA-positive patients vs five of 35 ctDNA-negative patients (59% vs 14%, P = 0.002). Among the 21 patients undergoing cystectomy, pathological upstaging occurred in seven of nine ctDNA-positive patients and one of 12 ctDNA-negative patients (78% vs 8%, P = 0.002). Distant recurrence occurred in three of 17 (18%) ctDNA-positive patients and in none of ctDNA-negative patients. TP53 alterations were enriched in ctDNA-positive tumours, whereas fibroblast growth factor receptor (FGFR3) alterations were more frequent in ctDNA-negative tumours. Limitations include the small cohort and limited follow-up. Longitudinal ctDNA testing in high-risk NMIBC identifies a subgroup with higher risk of clinical and pathological upstaging and distant recurrence, often without corresponding cystoscopic or radiographic evidence. ctDNA-positivity reflects aggressive tumour biology and may help identify patients unlikely to benefit from continued intravesical salvage therapy. These findings support further evaluation of ctDNA as a potential risk stratification tool and motivate prospective studies of ctDNA-guided management.