Organ-specific Tumor Response to Avelumab Maintenance Therapy for Advanced Urothelial Carcinoma: A Multicenter Retrospective Study.

Background/aim: The organ-specific therapeutic effects of avelumab for the maintenance treatment of advanced urothelial carcinoma (UC) are unclear.

Patients And Methods: Patients who received avelumab for advanced UC that had not progressed with first-line platinum-based chemotherapy and who had measurable disease were retrospectively analyzed. The organ-specific response was evaluated, and progression-free survival (PFS) and overall survival (OS) were estimated.

Results: We analyzed 42 patients (male, n=31; median age, 72 years). The overall response rate [complete response (CR)+ partial response (PR)] and disease control rate (CR+PR+stable disease) were 2.4% and 47.6%, respectively. In total, 27, 11, 8 and 5 patients had measurable lymph node [organ-specific response rate (OSRR) 7.4%, organ-specific disease control rate (OSDCR) 59.3%], lung (OSRR 18.2%, OSDCR 36.4%), primary tumor organ (OSRR 0%, OSDCR 100%) and liver (OSRR 0%, OSDCR 100%) disease, respectively. The median PFS and OS was 3.8 months and 20.2 months, respectively. Regarding organ-specific PFS, a log-rank test confirmed significant differences between patients with and without primary tumor organ disease (p=0.009) and patients with and without liver metastasis (p=0.015). Regarding organ-specific OS, a log-rank test revealed no significant differences between patients with and without metastatic disease for all organs (lung: p=0.835; lymph node: p=0.914; bone: p=0.257; primary tumor: p=0.057; liver: p=0.893).

Conclusion: In patients receiving avelumab maintenance therapy, no significant differences in OS were observed between patients with and without metastasis to any organ, including the primary organ, although metastases and the primary tumor organ disease showed different responses.