Association Between Blood Transfusion and Survival Outcomes in Metastatic Cutaneous Melanoma Treated with Nivolumab.

Objective: Immune checkpoint inhibitors (ICIs) are a cornerstone in the treatment of metastatic cutaneous malignant melanoma (cMM). Blood transfusions exert immunomodulatory effects that may impair antitumor immunity; however, their impact on survival outcomes in patients receiving ICIs remains unclear. This study evaluated the association between blood transfusion and survival outcomes in patients with metastatic cMM treated with nivolumab. Methods: In this retrospective cohort study, 57 patients with metastatic cMM who received nivolumab as second-line therapy between January 2018 and December 2023 were analyzed. Blood transfusion exposure during the metastatic stage and survival outcomes, including progression-free survival (PFS) and overall survival (OS), were assessed. Results: The median age was 60.0 years (range, 25.0-87.0). Median follow-up was 55.0 months. Median PFS was 10.23 months (95% confidence interval [CI], not estimable to 21.53), and median OS was 31.93 months (95% CI, not estimable to 66.31). Kaplan-Meier analysis demonstrated significantly worse PFS and OS among patients who received red blood cell (RBC) transfusions (Log Rank, p = 0.024, p = 0.016, respectively). In univariate Cox regression analysis, melanoma localization, brain metastases at metastatic onset, shorter nivolumab duration, and RBC transfusion exposure were associated with poorer survival outcomes. Conclusion: Blood transfusion during the metastatic stage was associated with reduced survival in patients with metastatic cMM receiving nivolumab. These findings suggest that transfusion-related immunomodulation may be associated with reduced immunotherapy efficacy and highlight RBC transfusion as a clinically relevant and potentially modifiable factor in patient management.