Organ-specific tumor response to enfortumab vedotin in metastatic urothelial carcinoma: a multicenter retrospective study

Background Despite advancements in treatment options for metastatic urothelial carcinoma (mUC), therapeutic choices remain limited for patients with disease refractory to platinum-based chemotherapy (PBC) and immune checkpoint inhibitors (ICIs). Enfortumab vedotin (EV) has demonstrated significant efficacy in later lines of therapy for mUC; however, its organ-specific responses remain uncertain.Methods We conducted a retrospective study of 69 patients with mUC who received EV following treatment with PBC and ICIs. Efficacy was assessed using Response Evaluation Criteria in Solid Tumors, with organ-specific response rates (OSRR) and organ-specific disease control rates (OSCR) calculated across different metastatic sites. Multivariate Cox regression analysis was performed to identify independent predictors of disease progression and survival.Results The median progression-free survival (PFS) was 8.3 months, whereas the median overall survival (OS) was 18.0 months. The objective response rate (ORR) was 53.6%, and the disease control rate (DCR) was 82.6%. OSCR was >= 70% across all metastatic sites, confirming the broad efficacy of EV. Liver metastases exhibited the highest OSRR at 66.7%, whereas bone metastases had the lowest OSRR at 12.5%. Tumor burden reduction was significantly lower in bone metastases compared to other metastatic sites. Disease progression was predominantly observed at target lesions, with a median time to progression of 3 months. Eastern Cooperative Oncology Group performance status and serum C-reactive protein levels were identified as significant independent predictors of PFS and OS.Conclusion EV exhibited favorable organ-specific tumor responses in mUC, with particularly high efficacy against liver metastasis. However, response rates were lower in bone metastases. No significant differences in organ-specific overall survival were observed. Enfortumab vedotin showed broad efficacy in metastatic urothelial carcinoma, with high response rates in liver metastasis but lower responses in bone metastases. Performance status and CRP were key survival predictors.