The tumour-associated stroma correlates with poor clinical outcomes and immunoevasive contexture in patients with upper tract urothelial carcinoma: results from a multicenter real-world study (TSU-01 Study)

BACKGROUND:In this real-world study, we aimed to elucidate the predictive value of tumour-associated stroma for clinical prognostic and therapeutic response in upper tract urothelial carcinoma (UTUC) by reviewing the clinicopathologic characteristics of 1015 UTUC patients through a nationwide multicenter analysis. METHODS:The tumour-stroma ratio (TSR) was assessed based on tissue sections stained for hematoxylin and eosin (H&E), and patients were further stratified into stroma-high (>50% stroma) and stroma-low group (≤50% stroma). Kaplan-Meier curve and Cox regression hazard analysis were conducted to assess the survival outcomes of UTUC patients. Bioinformatics analysis and immunostaining analysis were applied to portray the tumour microenvironment (TME). RESULTS:Stroma-high UTUC was significantly associated with poorer survival outcomes and inferior chemotherapeutic responsiveness. Our established nomogram achieved a high prognostic accuracy in predicting overall survival and cancer-specific survival in both of the discovery cohort (area under the curve [AUC] 0.663 and 0.712) and the validation cohort (AUC 0.741 and 0.747). Moreover, stroma-high UTUC was correlated with immunoevasive TME accompanied by increased cancer-associated fibroblasts, tumour-associated macrophages and, conspicuously a cluster of highly exhausted CD8+ T cells. CONCLUSION:Our results showed stroma-high UTUC was associated with an inferior prognosis and an immunoevasive TME with exhausted CD8+ T cells in UTUC patients. Our TSR-based nomogram could be used to refine prognosis and inform treatment decisions of patients with UTUC.