Histopathological improvement in kidney AL amyloid deposits following daratumumab-based chemotherapy and autologous peripheral blood stem cell transplantation: a case report.

AL amyloidosis is characterized by extracellular deposition of immunoglobulin light-chain fibrils, frequently leading to kidney involvement and progressive organ dysfunction. We report a case of kidney AL amyloidosis secondary to multiple myeloma in which daratumumab-based chemotherapy combined with autologous peripheral blood stem cell transplantation resulted in marked improvement, as confirmed by sequential kidney biopsy. The initial biopsy revealed vascular-dominant amyloid deposition, whereas the second biopsy obtained 2 years later demonstrated a marked reduction in amyloid burden, particularly within the vascular compartments. This histopathological improvement corresponded with hematologic remission and stabilization of kidney function. The observed reduction in tissue amyloid deposits was presumed to result from suppression of amyloidogenic light chains, leading to inhibition of new fibril formation and subsequent tissue remodeling. Our findings provide direct pathological evidence that daratumumab-based combination therapy, through immune-mediated plasma cell depletion, may indirectly promote the regression of amyloid deposits and contribute to functional recovery.