Collapsing Glomerulopathy and Thrombotic Microangiopathy after Chimeric Antigen Receptor T Cell Therapy

Chimeric antigen receptor T-cell (CAR-T) therapy is increasingly used in hematologic malignancies but can be complicated by immune-mediated toxicities, including acute kidney injury, which is typically attributed to hemodynamic factors or acute tubular injury. Glomerular diseases in this setting are exceedingly rare, with only isolated case reports in the literature. We report a 65-year-old African American man with relapsed multiple myeloma who developed AKI with nephrotic-range proteinuria following BCMA-directed CAR-T therapy, in the context of cytokine release syndrome and immune effector cell-associated hemophagocytic lymphohistiocytosis syndrome. Kidney biopsy demonstrated, the coexistence of collapsing glomerulopathy and biopsy-proven thrombotic microangiopathy, suggesting combined podocyte and endothelial injury. The patient was managed with supportive measures and immunomodulatory therapy targeting systemic inflammation, resulting in improvement in kidney function and significant reduction in proteinuria alongside a sustained oncologic response. Recognition of nephrotic-range proteinuria or persistent kidney dysfunction after CAR-T therapy should prompt consideration of immune effector cell-associated glomerulopathy and evaluation with kidney biopsy when appropriate.