Complete Response as an Intermediate End Point in Patients Receiving Salvage Systemic Therapy for Urothelial Carcinoma

BACKGROUND: The complete remission (CR) rate with salvage systemic therapy for urothelial carcinoma (UC) is unclear, and its value as an intermediate end point and association with survival are unknown. MATERIALS AND METHODS: Data from phase II trials of salvage chemotherapy and/or biologic agents were pooled. Data regarding response, overall survival (OS), progression-free survival (PFS), time from prior chemotherapy, hemoglobin, performance status, and liver metastasis status were collected. Cox proportional hazards regression was used to evaluate the association of CR and other prognostic factors with outcomes. RESULTS: A total of 789 of 818 patients enrolled in 12 phase II trials had evaluable data. CR and partial response were seen in 14 (1.8%) and 109 (13.8%) patients. Median (95% confidence interval) OS for those with a CR was 21.5 (14.2-34.3) months, compared with 6.7 (6.0-7.0) months in those without a CR (P < .001). Median (95% confidence interval) PFS for those with a CR was 15.7 (8.2-27.1) months, compared with 2.6 (2.4-2.8) months for those without a CR (P < .001). Prior cisplatin and time from prior chemotherapy of ≥ 3 months were associated with CR (P < .05). The presence of poor prognostic factors and suboptimal response to prior therapy did not preclude CR. CONCLUSION: CR occurs in 1.8% of patients receiving salvage therapy for advanced UC and is strongly associated with durable OS and PFS. CR warrants validation as an intermediate end point and may help select agents for further investigation and tumors for molecular interrogation.