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.
Keywords: Bladder cancer; Long-term followup; Response rate; Surrogate marker; immüne checkpoint inhibitors.
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