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.