Treatment of Refractory Monoclonal Immunoglobulin Deposition Disease With <scp>BCMA</scp> Bispecific Antibody

Monoclonal immunoglobulin deposition disease (MIDD) is characterized by deposits of intact monoclonal immunoglobulin protein, most commonly in the kidney, but other organs such as the heart can be involved. Patients are treated with plasma cell-directed therapies. Here we describe the first reported case of a patient with refractory MIDD with renal and cardiac involvement who was successfully treated with a BCMA-drected therapy. After achieving a deep hematologic response, the patient achieved a cardiac organ response as well. BCMA-directed therapy can be valuable for patients with refractory monoclonal immunoglobulin deposition disease.