Rituximab as Rescue Therapy for Atezolizumab-Induced IgA Vasculitis.

Immune checkpoint inhibitors have transformed cancer therapy but are associated with immune-related adverse events, including kidney injury. Although acute interstitial nephritis is the most common renal immune-related adverse events, glomerular diseases such as immunoglobulin A (IgA) vasculitis remain rare and poorly characterized. We report the first biopsy-confirmed case of IgA vasculitis with crescentic glomerulonephritis associated with the programmed death-ligand 1 inhibitor atezolizumab. A 75-year-old man with metastatic small-cell neuroendocrine prostate carcinoma developed a skin palpable purpuric rash after atezolizumab exposure treated with topical corticosteroids, with subsequent development of acute kidney injury. Kidney biopsy demonstrated IgA-dominant necrotizing and crescentic glomerulonephritis, consistent with IgA vasculitis. High-dose oral and intravenous corticosteroids resulted in only partial renal improvement and persistent systemic inflammation. Subsequent treatment with rituximab (RTX) led to sustained stabilization of kidney function, normalization of previously elevated inflammatory cytokines (tumor necrosis factor-α, interleukin 18, soluble interleukin-2 receptor), and complete peripheral B-cell depletion. Although the malignancy later progressed, kidney function remained stable following RTX therapy. This case highlights IgA vasculitis as a rare but serious renal complication of programmed death-ligand 1 inhibition and supports RTX as a potential rescue therapy in corticosteroid-refractory cases. Careful biomarker monitoring and multidisciplinary management are essential to balance renal protection with oncologic outcomes.