BCMA CAR T for AL Amyloidosis After Plasmacytic Relapse of Lymphoplasmacytic Lymphoma.

Introduction: Lambda immunoglobulin light chain (AL) amyloidosis associated with non-IgM lymphoplasmacytic lymphoma (LPL) is rare and often refractory to conventional therapies. Treatment options for relapsed disease remain limited. Methods: Here we describe the case of a patient with a history of LPL-associated AL amyloidosis who had previously been treated with multiple B-cell- and plasma-cell-directed regimens. At the time of relapse, pathology demonstrated plasmacytic histology, with BCMA-expressing plasma cells by immunohistochemistry and no detectable B-cell infiltrate. The patient subsequently received investigational B-cell maturation antigen (BCMA)-directed chimeric antigen receptor (CAR) T-cell therapy. Results: Following BCMA-directed CAR T-cell therapy, the patient achieved a complete hematologic response. Conclusion: This case highlights the biologic complexity of LPL-associated AL amyloidosis and supports the use of BCMA-targeted therapy, especially when the relapsing or residual disease is comprised by the plasma cell component. Trial Registration: ClinicalTrials.gov identifier: NCT06097832.