Failure of mobilization of hematopoietic stem cells associated with elevated serum levels of anti-CD38 monoclonal antibody.

ABSTRACT

Daratumumab is an anti-CD38 antibody that is increasingly incorporated in induction regimens for treating patients with newly diagnosed multiple myeloma (NDMM). Previous reports have demonstrated a lower yield of hematopoietic stem cells (HSCs) after induction with daratumumab; however, none of them reported a failure to collect an adequate number of HSCs. We describe a case of adequate HSC mobilization failure in a patient who inadvertently received excessive doses of daratumumab and was confirmed by higher-than-expected circulating levels of daratumumab by mass spectrometry. Eventual clearance of circulating daratumumab was associated with the successful mobilization and harvesting of HSCs.