Renal Adverse Effects of Immune Checkpoint Inhibitors in Cancer Patients: Diagnosis and Management

The advent of immune checkpoint inhibitors (ICIs) has radically altered the prognosis of numerous cancers, but it has also introduced a spectrum of immune-related adverse events affecting multiple organs. This review covers the fundamentals of the antitumor immune response and the various ICIs (anti–CTLA-4, anti–PD-1/PD-L1), as well as the description, mechanism, and management of their toxicities, with a special focus on renal complications. We examine the incidence and timing of renal injuries (acute interstitial nephritis, acute tubular necrosis, glomerulopathies), the role of diagnostics (laboratory evaluation, urinary sediment analysis, and kidney biopsy), and emerging research on urinary biomarkers. Risk factors—preexisting chronic kidney disease, metabolic comorbidities (e.g., diabetes), advanced age, concomitant use of nephrotoxic drugs, or combination ICI regimens—enable personalized monitoring and prevention of renal injury. Management of ICI-associated acute kidney injury involves early drug discontinuation, glucocorticoid therapy (intravenous and/or oral tapering over 4–6 weeks), and, in refractory cases, second-line immunosuppressants (mycophenolate mofetil, infliximab). Re-challenge is reserved for toxicities ≤ grade 2 with stable renal recovery, after a minimum interval of two months. Clinical outcomes indicate that over 60% of patients regain baseline renal function, fewer than 2% require dialysis, and renal-related mortality is minimal, although ICI discontinuation may impact oncologic survival. The degree of interstitial fibrosis on biopsy and the promptness of intervention emerge as key prognostic factors. Finally, the need for multidisciplinary protocols (Oncology, Nephrology, Pathology) and prospective studies validating noninvasive biomarkers is emphasized to optimize renal safety without compromising the therapeutic benefits of immunotherapy.