Aims: Adjuvant chemotherapy after radical cystectomy can reduce the risk of recurrence and death in advanced muscle-invasive urothelial bladder cancer (MIBC). Molecular subtypes have been shown to be associated with survival. However, their predictive value to guide treatment decisions is controversial and data to use subtypes as guidance for adjuvant chemotherapy is sparse. We aimed to assess survival rates based on MIBC consensus molecular subtypes with and without adjuvant chemotherapy.
Methods: Gene expression profiles of 143 patients with MIBC undergoing radical cystectomy were determined from formalin-fixed, paraffin-embedded specimen to assign consensus molecular subtypes. Expression of programmed cell death ligand-1 (PD-L1) and immune cell infiltration were determined using multiplex immunofluorescence. Matched-pair analysis was performed to evaluate the effect of adjuvant chemotherapy on overall survival (OS) for molecular subtypes applying Kaplan-Meier and Cox regression survival analyses.
Results: Samples were luminal papillary: 9.1% (n=13), luminal non-specified: 6.3% (n=9), luminal unstable: 4.9% (n=7), stroma-rich: 27.9% (n=40), basal/squamous (Ba/Sq): 48.9% (n=70) and neuroendocrine-like (NE-like): 2.8% (n=4). Ba/Sq tumours had the highest concentration of PD-L1+ tumour and immune cells. Patients with luminal subtypes had better OS than those with NE-like (HR 0.2, 95% CI 0.1 to 0.7, p<0.05) and Ba/Sq (HR 0.5, 95% CI 0.2 to 0.9, p<0.05). No survival benefit with adjuvant chemotherapy was observed for luminal tumours, whereas Ba/Sq had significantly improved survival rates with adjuvant chemotherapy. Retrospective design and sample size are the main limitations.
Conclusion: Consensus molecular subtypes can be used to stratify patients with MIBC. Luminal tumours have the best prognosis and less benefit when receiving adjuvant chemotherapy compared with Ba/Sq tumours.
Keywords: Biomarkers, Tumor; CHEMOTHERAPY; MOLECULAR BIOLOGY; Medical Oncology; Urinary Bladder.
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