The nascent role of circulating tumour <scp>DNA</scp> in the management of non‐muscle‐invasive bladder cancer

We have recently published data demonstrating that 11% of patients with treatment-naïve high-grade pT1 urothelial bladder carcinoma harbour detectable circulating tumour DNA (ctDNA) at the time of diagnosis [1]; ctDNA-positivity was associated with significantly worse progression-free survival, disease-specific survival, and overall survival (OS) compared to those patients who were ctDNA-negative [1]. The cohort comprised a near 50/50 mix of European Association of Urology (EAU) high-risk (HR) and very HR non-muscle-invasive bladder cancer (NMIBC), with no difference in OS between these two clinical risk groups [1]. The ctDNA detection assay was based upon the GALEAS™ Bladder gene panel (Nonacus Ltd, Birmingham, UK), which we developed for the urine-based diagnosis of bladder cancer [2], using data from accompanying tissue or urine samples to inform the detection of ctDNA at a limit of detection (LoD) of 0.04% variant allele frequency (VAF). We initially presented these data at the 40th Annual EAU Congress in Madrid in 2025; at the same congress, Ben David et al. [3] presented data from 49 patients with NMIBC who underwent ctDNA testing prior to cystectomy. With the Signatera ctDNA assay (LoD 0.01% VAF), 20 of these patients (41%) were ctDNA-positive pre-cystectomy, with ctDNA-positivity associated with upstaging to T2+ disease in 90% and lymph node metastases in 50% [3]. Hence, most of these patients with NMIBC were under-staged by transurethral resection of bladder tumour (TURBT)/re-TURBT and/or imaging.; however, two of the 21 patients classified as pT1 after cystectomy (9.5%) had been ctDNA-positive before cystectomy. Hence, ctDNA-positive NMIBC is a genuine phenomenon that requires careful consideration by the urological oncology community – ctDNA shedding appears to indicate more aggressive disease with a higher risk of dissemination at an early stage. Conceptually, these findings align with the Stein et al. [4] cystectomy series in which 6.7% of cystectomy-staged T1 patients had lymph-node positive disease. In the setting of MIBC, ctDNA positivity permits the early detection of metastatic relapse and predicts prognosis, and so ctDNA monitoring before, during and after treatment is becoming an important clinical tool in disease management, highlighted by the IMvigor011 (ClinicalTrials.gov identifier: NCT04660344) [5] and TOMBOLA (NCT04138628) [6] studies. These roles in MIBC provide an initial roadmap for the utilisation of ctDNA monitoring in NMIBC. The NMIBC ctDNA data from us and others are particularly relevant to clinical trials for both BCG-naïve and BCG-exposed patients with HR NMIBC. Should ctDNA status now become an important factor in the interpretation of outcomes from immune checkpoint inhibitor studies in these settings, perhaps demonstrating relationships that echo IMvigor010 (NCT02450331) [7]? Should ctDNA status become a stratification factor for randomisation and/or for determining whether patients are eligible for intravesical therapies or not? One could also argue that longitudinal ctDNA monitoring is essential so as to escalate treatment in trial patients who may be developing or harbouring occult metastatic disease, with ctDNA status potentially representing an additional trial endpoint. However, in parallel to answering these questions, the urological oncology community also has to consider how to treat ctDNA-positive HR-NMIBC and, possibly, what advanced imaging modalities may be required to inform treatment strategies – both are considerations that we very much encourage. Furthermore, with a low prevalence of ctDNA-positivity in patients with NMIBC compared to MIBC and the very high cost of existing commercially-available tests, can we better select who to test or can we develop less expensive tests? For the former, there may be associations with gene expression-based NMIBC molecular subtypes that could be leveraged and we plan to investigate this. For the latter, we contend that the GALEAS Bladder panel represents the basis of a cost-effective test that could be utilised in this setting using existing infrastructure [1], especially if patients have already undergone GALEAS Bladder urine testing during their diagnostic evaluation [2]. Cost becomes a key factor if more frequent monitoring is more important than the use of ultrasensitive assays for the early detection of molecular relapse [8]. In summary, the role of ctDNA in the management of patients with NMIBC is nascent with several important questions to resolve. To accumulate the insight that we need for clinical implementation, we recommend that the urological oncology community leverages the biospecimens already collected by large clinical trials in the HR-NMIBC setting (e.g., POTOMAC trial, NCT03528694) and those to be collected by trials in set-up (e.g., TRAIN trial, NCT07268339) to: (i) validate our published findings regarding baseline ctDNA status and outcomes [1], and (ii) gain understanding of subsequent ctDNA dynamics during and after bladder-sparing therapies. Biospecimens from cystectomy studies (e.g., iROC trial, NCT03049410) would permit the assessment of associations between NMIBC ctDNA status and established prognostic clinico-pathological factors, such as tumour size, lymphovascular invasion, and lymph node status. Clearly, the costs of existing commercially-available tests will make such research challenging for investigators and funders. Notwithstanding, the role of ctDNA in patients with NMIBC will likely be just as valuable as the role that is now emerging and expanding for ctDNA in patients with MIBC. We anticipate that within the next decade, all patients with HR-NMIBC and MIBC will routinely undergo ctDNA testing. Richard Bryan is an unpaid charity trustee for Action Bladder Cancer UK (UK), an advisory board member for Nonacus Limited (UK), and receives consultancy fees from Cystotech ApS (Denmark) and Nonacus Limited (UK). Richard Bryan and Douglas Ward co-developed the GALEAS™ Bladder test with Nonacus Limited (UK).