Sodium Levels and Outcomes in Patients With Metastatic Renal Cell Carcinoma Receiving Nivolumab

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IMPORTANCE Low sodium levels have been associated with negative outcomes among patients with metastatic renal cell carcinoma (mRCC) receiving therapies other than immune checkpoint inhibitors (ICIs). OBJECTIVE To investigate the role of natremia in patients with mRCC receiving nivolumab as a second-line or subsequent therapy. DESIGN, SETTING, AND PARTICIPANTS In this retrospective cohort study, the clinical and biochemical data of patients with mRCC receiving nivolumab were collected from October 2015 to November 2019 as part of a multicenter Italian study. Data analysis was performed from February to March 2023. EXPOSURE Nivolumab was administered intravenously at a dose of 3 mg/kg every 2 weeks and, since May 2018, at a fixed dose of 240 mg every 2 weeks or 480 mg every 4 weeks. Patients were divided into 2 groups according to their median serum sodium value (<140 or ≥140 mEq/L). MAIN OUTCOMES AND MEASURES The primary outcomes were the associations of pre-ICI and post-ICI sodium levels with overall survival (OS), progression-free survival (PFS), objective response rate, and disease control rate (DCR). The Kaplan-Meier method was used to estimate PFS and OS, and differences between groups were compared using the log-rank test. RESULTS A total of 401 patients with mRCC receiving nivolumab as second-line therapy were evaluated, and 355 eligible patients (median [range] age, 76 [44-84] years; 258 male patients [72.7%]) were included in the final cohort. Among patients with pre-ICI sodium greater than or equal to 140 mEq/L compared with those with sodium less than 140 mEq/L, the median PFS was 9.3 months (95% CI, 6.5-11.5 months) vs 7.4 months (95% CI, 4.6-10.1 months; P = .90), and the median OS was 29.2 months (95% CI, 21.8-35.9 months) vs 20.0 months (95% CI, 14.1-26.8 months; P = .03). Patients with post-ICI sodium values greater than or equal to 140 mEq/L had longer PFS (11.1 months [95% CI, 8.5-1.5 months] vs 5.1 months [95% CI, 4.1-7.5 months]; P = .01) and OS (32.9 months [95% CI, 25.1-42.6 months] vs 17.1 months [95% CI, 12.6-24.5 months]; P = .006) compared with patients with sodium values less than 140 mEq/L. Patients with both pre-ICI and post-ICI sodium values greater than or equal to 140 mEq/L exhibited a significant improvement in clinical outcomes compared with those with a value less than 140 mEq/L (PFS, 11.5 months [95% CI, 8.8-16.4 months] vs 5.8 months [95% CI, 4.4-8.3 months]; P = .008); OS, 37.6 months [95% CI, 29.0-49.9 months] vs 19.4 months [95% CI, 14.1-24.5 months]; P = .01). Moreover, sodium levels greater than or equal to 140 mEq/L were associated with significantly better DCR than lower sodium levels. CONCLUSIONS AND RELEVANCE In this retrospective cohort study of patients with mRCC receiving nivolumab, sodium values greater than or equal to 140 mEq/L, both before and/or after ICI, were associated with better OS and PFS, as well as a higher DCR, compared with levels less than 140 mEq/L. These findings suggest that sodium levels may be associated with survival outcomes in patients with mRCC and may have potential use as variables to consider in patients' risk scores.

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