Abstract / Summary
We assessed the outcomes of high-dose intravenous melphalan with autologous peripheral blood hematopoietic stem cell transplantation (HDM-ASCT) in treating patients with multiple myeloma (MM) in a real-world setting. In this single-center retrospective analysis, 50 consecutive patients with newly diagnosed MM who received HDM-ASCT were evaluated. The primary endpoint was PFS; secondary endpoints included treatment response and post-transplant minimal residual disease (MRD) status. All 50 patients achieved hematopoietic reconstitution without transplant-related mortality. The rate of ≥very good partial response (VGPR) improved from 54% before HDM-ASCT to 82% after HDM-ASCT. The complete response (CR) rate increased from 30% to 62%. The MRD negativity rate improved from 44.4% before HDM-ASCT to 64.4% after HDM-ASCT. As of October 31, 2023, the median follow-up time was 25 months (7.5–49.5 months), with 12 patients experiencing relapse and 5 deaths. The estimated 3-year PFS and overall survival rates were 70.5% and 88.4%, respectively. Patients with CR and VGPR after HDM-ASCT had a significantly longer estimated 3-year PFS compared to patients with PR ( p = 0.039, p = 0.047). The estimated 3-year PFS rates of MRD-negative patients before (84.7% vs. 62.8%) and after HDM-ASCT (80.5% vs. 57.6%) were numerically higher than those of MRD-positive patients ( p = 0.34, p = 0.15). In the 12-month landmark analysis, no relapses occurred among the 22 patients with sustained MRD negativity for ≥ 1 year, whereas 6 of the 14 patients without sustained negativity experienced disease progression (log-rank p = 0.001; Fisher exact test p = 0.0015). The 3-year PFS rates of patients with standard-risk and high-risk cytogenetic abnormalities were 71.9% and 66.0%, respectively ( P = 0.402). In this real-world cohort, HDM-ASCT was associated with improved CR and MRD negativity rates in MM patients. Patients who achieved deeper responses before ASCT tended to have better PFS outcomes. Regular monitoring of MRD is needed after ASCT, and sustained MRD negativity for one year may be associated with favorable long-term PFS, although this finding is exploratory and requires validation. Not applicable.