Introduction: Clinical guidelines recommend neoadjuvant chemotherapy (NAC) for the treatment of muscle-invasive bladder cancer (MIBC). However, NAC prior to radical cystectomy (RC) is associated with treatment-related toxicity and confers a modest survival benefit. Here, we aimed to identify MIBC patients who may avoid NAC by combining circulating tumor cell status and molecular subtypes in a composite biomarker approach. Methods: TURBT tissue specimen were collected from clinical stage T2-T4aN0-N1M0 MIBC cases that were included within the CirGuidance study (NL3954), a prospective trial that analyzed circulating tumor cell (CTC) status in a patient’s blood sample using the CELLSEARCH system. For the present study, transcriptome-wide expression profiling was performed on 234 TURBT samples using an array-based approach. Molecular subtypes, long non-coding RNA (lncRNA) based FGFR3+ status and gene signatures were determined as described previously (de Jong et al., Genome Med. 2019). The primary endpoint of this study was cancer-specific mortality (CSM), calculated as the date of study inclusion till date of bladder cancer related death. Median follow-up was 28.8 (IQR: 16.6-40.2) months. Results: Of 234 patients, 21 (9%) were treated with NAC and RC, while 213 (91%) received RC alone. A CTC-negative status was observed in 172 (81%) of RC-only cases. Molecular subtyping identified 28 luminal FGFR3+ cases with high FGFR3, SHH and p53 pathway activity, and lower EMT hallmark scores. Adjusting for clinical risk factors, both CTC and FGFR3+ status were significant predictors for cancer specific mortality on MVA (P <0.05). Of interest, the subgroup of FGFR3+ cases that were CTC-negative (N=26) showed most favorable outcomes with only one CSM event after a median of 33.4 (IQR: 24.8-44.5) months of follow-up. Conclusions: Using a composite biomarker approach of blood-based CTC status and molecular subtyping, we identified a biologically distinct subgroup of MIBC with favorable prognosis after RC-only, validating the performance of a previously developed lncRNA based FGFR3+ classifier. Clinical trials which withhold NAC from CTC-negative, FGFR3+ MIBC patients are warranted. SOURCE OF Funding: Gene expression profiles were generated using the Decipher Bladder assay.
