Role of Daratumumab, Lenalidomide, and Dexamethasone in Transplantation-Eligible Patients with Multiple Myeloma After the Failure of Bortezomib-Based Induction Therapy

<b>Background/Objectives:</b> The role of daratumumab, lenalidomide, and dexamethasone (DRd) in autologous stem cell transplantation (ASCT)-eligible patients with multiple myeloma (MM) after first-line bortezomib, cyclophosphamide, and dexamethasone (VCd) treatment is not yet established. <b>Methods:</b> We retrospectively evaluated ASCT-eligible patients with MM who received second-line therapy with DRd after initial induction therapy with VCd between 2017 and 2023 (salvage group). For comparison, patients who successfully underwent per-protocol treatment with VCd induction, followed by ASCT during the same period, were selected (control group). <b>Results:</b> Eight patients with a median age of 61 years (range, 36-68 years) were included in the salvage group. After a median of 5 DRd cycles, the best response was partial response (PR) in two patients (25%) and a very good partial response (VGPR) in six (75%). All patients underwent ASCT, resulting in PR in one (13%), VGPR in four (50%), and stringent complete response in three (38%). Measurable residual disease (MRD) assessed using multicolor flow cytometry was negative in four patients (50%). The controls included thirteen patients with a median age of 60 years (range, 44-64 years). While most patients in both groups received various post-ASCT therapies, the post-ASCT 2-year time to the next treatment rate was slightly better in the salvage group than in the control group (88% vs. 49%, <i>p</i> = 0.089). However, hypogammaglobulinemia was more common in the salvage group (75% vs. 15%, <i>p</i> = 0.018). <b>Conclusions:</b> This small case series suggests that DRd is promising for ASCT-eligible patients with MM after VCd failure.