A case of treatment-related leukoencephalopathy during combination therapy with daratumumab, lenalidomide, and low-dose dexamethasone for multiple myeloma

A 75-year-old woman with multiple myeloma was admitted due to an acute disturbance of consciousness and aphasia two months after administration of daratumumab, lenalidomide and dexamethasone combination therapy (DLd therapy). Brain MRI on admission showed no acute ischemic changes. She was treated with antiepileptic drugs, and DLd therapy was discontinued, but her consciousness deteriorated, and follow-up brain MRI showed progressive FLAIR high-signal intensity lesions in the cerebral deep white matter bilaterally. Though methylprednisolone pulse therapy and high-dose intravenous immunoglobulin were ineffective, plasma exchange improved her consciousness, and she began to speak. In addition, her MRI findings improved. Progressive multifocal leukoencephalopathy induced by drugs for multiple myeloma has been reported, but, in this case, leukoencephalopathy associated with daratumumab was suspected because JC virus DNA was not detected in her cerebrospinal fluid.