Immunotherapy-Associated Renal Dysfunction in Metastatic Cancer: An Emerging Challenge in Onco-Nephrology

Background: Immune checkpoint inhibitors (ICIs) have significantly modified the management of metastatic cancers; however, their nephrotoxic potential remains underappreciated. While acute kidney injury (AKI) is a known immune-related adverse event, the subacute spectrum of kidney injury—termed acute kidney disease (AKD)—has not been adequately explored in this setting. Methods: We conducted a retrospective cohort study in 226 adult patients with metastatic solid tumors who received ICIs between 2017 and 2023 at a single tertiary care center. AKD was defined according to the 2024 “Kidney Disease: Improving Global Outcomes” (KDIGO) criteria. Multivariable logistic regression was used to identify predictors of AKD. Results: AKD occurred in 46 patients (20.4%) within 90 days of ICI initiation, with 16 (7.1%) experiencing persistent dysfunction beyond 30 days. Independent predictors of AKD included higher body surface area (OR 8.17, p = 0.03) and baseline use of nonsteroidal anti-inflammatory drugs (OR 29.74, p = 0.014). Baseline antibiotics showed a trend toward association (p = 0.054). Concurrent chemotherapy was associated with a trend toward protection. The predictive model showed good discrimination (AUC 0.778). No significant differences in other grade ≥2 immune-related adverse events were observed between the AKD and non-AKD groups. Conclusions: AKD is a frequent and underrecognized renal complication in patients receiving ICIs, with implications for both renal and oncological outcomes. Identifying high-risk patients and integrating longitudinal renal monitoring into immunotherapy care pathways may improve safety and treatment continuity.