A rare case of daratumumab-associated encephalopathy in multiple myeloma.

Aim: Daratumumab, a CD38 monoclonal antibody, has been widely used in patients with multiple myeloma. Although a variety of adverse events have been reported, consciousness impairment has not been reported yet. We report a case of encephalopathy associated with daratumumab. Case presentation: A 57-year-old male, diagnosed with relapsed multiple myeloma, was treated with daratumumab. He developed a loss of consciousness after the first administration. Cerebral spinal fluid and magnetic resonance imaging of the brain suggested encephalopathy. Conclusion: It is recommended to be aware of rare but life threatening side effects of daratumumab. We present a case of rare encephalopathy characterized by consciousness disorder associated with daratumumab, which was successfully resolved on prompt institution of steroids, although the mechanism was unknown.