Objective Response Rate is a Surrogate Marker for Long-Term Overall Survival in Metastatic Urothelial Carcinoma Patients Treated With Immune Checkpoint Inhibitors.

BACKGROUND

This study aimed to evaluate the utility of RECIST criteria-based objective response rate (ORR) as a potential surrogate endpoint for long-term overall survival (OS) in patients with metastatic urothelial carcinoma who were treated with immune checkpoint inhibitors (ICIs).

METHODS

The primary endpoint was overall ORR and OS, duration of treatment (DoR) with ICIs. ORR was analyzed using Fisher's exact test. Median follow-up and OS were estimated by using the Kaplan-Meier method.

RESULTS

The median follow-up was 58 (1.15-71) months. Progression developed in 94 (47%) patients during the first 3 months of ICIs therapy. The treatment response to ICIs included complete response (CR), partial response (PR) and stable disease in 10% (n = 20), 23% (n = 46), and 20% (n = 41) of patients, respectively. The responder and nonresponder groups differed in terms of certain baseline characteristics, such as Bellmunt risk factors, and neutrophil-to-lymphocyte ratio (NLR). The 5-year OS rates for patients with CR and PR were 73% and 23%, respectively. The median DoR for CR, PR, and SD were 51.8 months (44.5-59.1), 20.7 months (16.7-24.6), and 8.8 months (5.5-12.1), respectively. Overall, 16(80%) patients with CR and 14(30%) patients with PR had an ongoing response at the time of the analysis. In the univariate analysis, NLR > 3, liver metastases, ECOG PS ≥ 1, and hemoglobin levels < 10 mg/dl, as well as the PR and CR, were all significantly associated with OS. In multivariate analysis, presence of liver metastases (HR 2.3; 95% CI, 1.3-4.2; P < .004) was found to be an independent determinant of short OS, while PR (HR 0.3; 95% CI, 0.15-0.5; P < .001) and CR (HR 0.06; 95% CI, 0.014-0.27; P < .001) were associated with improved OS.

CONCLUSIONS

In conclusion, this 5-year analysis of real-world data in the setting of metastatic urothelial cancer indicated a significant correlation between ORR, especially CR, and OS in patients who received ICIs. Therefore, identifying a potential surrogate marker for survival in patients treated with ICIs would represent an important advance in the early identification of patients' response or resistance to ICIs.