P-340: Real-world Data on the Use of Subcutaneous Daratumumab Plus Bortezomib, Thalidomide, and Dexamethasone in Transplant-eligible Patients With Newly Diagnosed Multiple Myeloma

Introduction: Subcutaneous daratumumab (DARA SC) + bortezomib/thalidomide/dexamethasone (VTd) is approved for the treatment of patients (pts) with newly diagnosed multiple myeloma (NDMM) eligible for autologous stem cell transplant (ASCT). However, there is a need for real-world (RW) data on DARA SC+VTd in routine clinical practice. Here we present RW data on the effectiveness and safety of DARA SC+VTd in ASCT-eligible pts with NDMM in Brazil.

Methods: The MMY4046 non-interventional, multicenter, observational, post-authorization safety study enrolled treatment-naïve pts with NDMM who were eligible for ASCT (at start of DARA SC+VTd) and completed ≥1 cycle of DARA SC+VTd per local practice by Sep 30, 2022. Exclusions included contraindication to DARA SC, plans to change treatment, receipt of investigational drugs, and participation in interventional studies. Data were collected retrospectively from the start of DARA SC+VTd (baseline) to study inclusion using medical records and prospectively from the study inclusion visit to 30 days post-consolidation via electronic case report forms. Data on pt and disease characteristics, response, stem cell collection, ASCT outcomes, treatment-emergent adverse events (TEAEs), and DARA SC+VTd treatment were collected.

Results: As of the data cutoff (Aug 8, 2023), 49 pts were included. Baseline median (range) age was 58 (38-73) yr, time since myeloma diagnosis was 0.7 (0-48.2) mo, and 93.8% pts had intent for consolidation therapy. Median (range) number of induction and consolidation cycles was 4 (1-6) and 2 (1-2), respectively; duration of treatment was 8.9 (1.0-15.7) mo. By the end of consolidation, 91.7% of pts achieved overall response (≥partial response), 89.6% achieved ≥very good partial response, and 25.0% achieved ≥complete response. Overall, 45 (91.8%) pts underwent stem cell mobilization (plerixafor given in 40.8%), with a median (range) stem cell yield of 5.7 (2.3-15.0)×10⁶ CD34⁺ cells/kg; 44 (89.8%) pts underwent ASCT, of which 43/44 (97.7%) pts had a successful ASCT. TEAEs occurred in 44 (89.8%) pts, grade 3/4 TEAEs in 24 (49.0%) pts, and serious TEAEs in 14 (28.6%) pts. Grade 3/4 neutropenia/febrile neutropenia occurred in 16 (32.7%) pts, primarily the during ASCT phase (10 [22.2%]); serious events occurred in 2 (4.1%) pts (both febrile neutropenia during ASCT phase). Grade 3/4 infections occurred in 9 (18.4%) pts, primarily during induction (6 [12.2%]); serious infections occurred in 10 (20.4%) pts, the most common being COVID-19 (10.2%) and pneumonia (4.1%). As of the cutoff, 1 pt had discontinued treatment (thalidomide only) due to a TEAE (paresthesia), and 1 pt had died (due to post-ASCT septic shock 32 d after the last DARA SC+VTd dose).

Conclusions: Results were consistent with the established profile of DARA SC+VTd, with no new safety concerns observed in RW practice. Notably, most pts achieved successful ASCT after DARA SC+VTd, supporting the frontline use of DARA SC+VTd in ASCT-eligible pts with NDMM.