High prevalence of iron deficiency among daratumumab-treated newly diagnosed multiple myeloma patients.

Iron deficiency (ID) is often overlooked in patients with haematological malignancies due to other potential aetiologies. Daratumumab, an anti-cluster of differentiation 38 (anti-CD38) monoclonal antibody, is commonly used for treating multiple myeloma (MM) in the upfront and relapsed/refractory settings. Although anaemia is a common haematological toxicity associated with daratumumab, the contribution of ID in MM patients has not been systematically investigated. We conducted a retrospective case-control study to evaluate the prevalence of ID in newly diagnosed MM (NDMM) patients. Cases were patients receiving daratumumab, ixazomib, lenalidomide and dexamethasone (Dara-IRD, n = 55). We compared this group with an age- and sex-matched cohort of patients with NDMM who received bortezomib, lenalidomide and dexamethasone (VRD, n = 20) as induction therapy. At 1-year, nearly 50% of Dara-IRD-treated patients met the criteria for ID (ferritin <30 mcg/L) compared with none of the VRD-treated controls. All Dara-IRD-treated patients had a decrease in ferritin at 1-year from baseline compared with only 45% of VRD-treated patients. These findings identify a marked clinical signal of ID among NDMM patients receiving daratumumab-based treatment. Although the study design does not establish causality or exclude regimen-related confounding, it highlights the need for increased awareness of the importance of monitoring iron status in MM patients treated with daratumumab-containing regimens.