CD38 and plasma cell myeloma: Just as daratumumab treatment can modulate CD38 and cMRP expression on myeloma cells, it may be that long-term exposure to daratumumab leads to attenuation of CD38 expression on CD34+ cells, perhaps affecting mobilization kinetics and lineage-specific progenitor cell frequencies or proliferative capacity, particularly when daratumumab is combined with other agents [13].