Tandem autologous stem cell transplant in multiple myeloma patients with minimal residual disease: an explorative study.

purposeTandem autologous stem cell transplantation (tASCT) is a viable option for high-risk multiple myeloma (MM) patients. Minimal residual disease (MRD), a real-time surrogate marker of disease burden, serves as a valuable measure of treatment response. This study evaluated the impact of tASCT on MRD dynamics in MM patients.

methodsWe analyzed data from a multicenter registry of 28 patients who underwent tASCT as frontline treatment between January 2019 and October 2024. Eligibility criteria included undergoing two ASCTs within one year, having MRD positivity before tASCT, and completing follow-up MRD assessment. Patients were stratified into two groups: extensive MRD clearance (≥ 50% reduction, n = 18) and modest MRD clearance (< 50% reduction, n = 10).

resultsAcross the entire cohort, mean MRD decreased from 0.111% pre-tASCT to 0.056% post-tASCT. Three patients achieved MRD negativity, 20 had reductions without negativity, and five experienced increases. The extensive clearance group showed significant MRD reduction (0.152% to 0.017%) and longer progression-free survival (PFS: 37.7 vs. 16.3 months, p = 0.013) compared with the modest clearance group, in which MRD increased (0.175% to 0.830%). Overall survival did not differ significantly.

conclusionstASCT provides clinical benefit for MRD-positive MM patients, particularly those achieving significant MRD reduction. These findings support tASCT as a feasible approach for MRD-positive patients following initial ASCT.