P-150: Autologous stem cell transplantation (ASCT) is still crucial for multiple myeloma (MM) patients with undetectable minimal residual disease after induction treatment

Introduction: Attaining undetectable minimal residual disease (MRD) is the current therapeutic goal for multiple myeloma (MM). But there is a current lack of data regarding the clinical benefit of autologous stem cell transplantation (ASCT) for myeloma patients achieving early MRD-negative status after induction treatment, in addition to the interaction of longitudinal MRD status with ASCT.

Methods: The present study included 407 transplant-eligible MM patients with available MRD status from the National Longitudinal Cohort of Hematological Diseases in China (NCT04645199), of whom 147 (34.4%) achieved early undetectable MRD and 182 (44.7%) received ASCT.

Results: Early MRD-negative status was associated with a lower risk of disease progression (HR=0.447; 95%CI, 0.333-0.600; P< 0.001) and death (HR=0.473; 95%CI, 0.320-0.700; P< 0.001). Of note, patients who achieved undetectable MRD early still benefitted from ASCT, with a remarkable improvement in the median MRD-negative duration (33.5 to 58.0 months, P< 0.001), progression-free survival (PFS; 46.0 to 88.3 months, P< 0.001), and overall survival (OS; 76.4 months to not reached, P=0.003). These clinical benefits were more pronounced in patients with aggressive features (high-risk cytogenetic abnormalities or high tumor burden) other than in standard-risk patients. Similar results were observed in patients with detectable MRD after induction treatment. Additionally, we identified four MRD-status transformation patterns following ASCT, which were strongly correlated with diverse survival outcomes (P < 0.001).

Conclusions: These findings emphasize the crucial role of ASCT in myeloma patients regardless of early MRD status, especially for high-risk patients. Longitudinal MRD conversion after ASCT also has a significant impact on risk stratification.