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.