Sustained Minimal Residual Disease (MRD) Negativity and Clinical Efficacy in Transplant-Ineligible (TIE) Newly Diagnosed Multiple Myeloma (NDMM) Patients (Pts) Treated with Daratumumab-Based Regimens: Analysis of Maia and Alcyone

Introduction: Daratumumab (DARA) is a human IgGκ monoclonal antibody targeting CD38 with a direct on-tumor and immunomodulatory mechanism of action, and has been approved across lines of therapy for the treatment of multiple myeloma. The addition of DARA to standard-of-care (SoC) regimens, lenalidomide and dexamethasone (D-Rd) and bortezomib, melphalan, and prednisone (D-VMP), in the phase 3 MAIA and ALCYONE clinical studies reduced the risk of disease progression or death by ≥44%, nearly doubled the rate of complete response (CR) or better, and induced a >3-fold increase in MRD-negativity rates (10-5 sensitivity threshold) vs SoC alone in pts with TIE NDMM. In both MAIA and ALCYONE, MRD negativity was associated with longer progression-free survival (PFS), irrespective of trial treatments. MRD negativity provides an index of deep clinical response and may be a more robust evaluation of disease control if sustained over time. Here, we evaluate MRD negativity, including sustained MRD negativity, in pts with TIE NDMM from MAIA and ALCYONE and its association with PFS with longer follow-up. Methods: Pts with NDMM ineligible for high-dose chemotherapy with stem cell transplantation due to age (≥65 years) or unacceptable coexisting conditions in MAIA and ALCYONE were randomized (1:1) to SoC ± DARA. Pts in MAIA received 28-day cycles of Rd (R: 25 mg PO on Days 1-21; d: 40 mg PO QW) ± DARA (16 mg/kg IV QW for Cycles 1-2, Q2W for Cycles 3-6, and Q4W thereafter). ALCYONE pts received up to nine 6-week cycles of VMP (V: 1.3 mg/m2 SC twice weekly during Weeks 1, 2, 4, and 5 of Cycle 1 and QW during Weeks 1, 2, 4, and 5 of Cycles 2-9; M: 9 mg/m2 PO on Days 1-4 of Cycles 1-9; and P: 60 mg/m2 PO on Days 1-4 of Cycles 1-9) ± DARA (16 mg/kg IV QW for Cycle 1, Q3W for Cycles 2-9, and Q4W for Cycles 10+). Study treatments continued until progressive disease or unacceptable toxicity. MRD was assessed in MAIA and ALCYONE in all pts who achieved a CR or stringent CR. For ≥CR pts, additional MRD assessments occurred at 12, 18, 24, and 30 months after the first dose in ALCYONE and at 12, 18, 24, 30, 36, 48, and 60 months in MAIA. MRD was assessed via next-generation sequencing using the clonoSEQ® assay (v.2.0; Adaptive Biotechnologies, Seattle, WA) at the 10-5 sensitivity threshold. Sustained MRD negativity was defined as the maintenance of MRD negativity confirmed ≥6 or ≥12 months apart with no MRD positive test in between and was evaluated in the intention-to-treat (ITT) popul