Role of Autologous Stem Cell Transplantation in Transplant-Eligible Dialysis-Dependent Multiple Myeloma Patients

Purpose: The role of autologous stem cell transplantation (ASCT) in transplant-eligible patients with dialysis-dependent multiple myeloma (DDMM) remains unclear. We compared outcomes between ASCT and non-ASCT approaches in newly diagnosed DDMM. Materials and Methods: In this multicenter retrospective study, 117 patients with newly diagnosed DDMM who remained dialysis-dependent throughout induction therapy were included. Patients who achieved dialysis independence during induction were excluded. In the ASCT group, patients also remained dialysis-dependent at transplantation. Results: Post-induction overall response and ≥VGPR rates were comparable between groups. In the ASCT group, responses deepened significantly after transplantation. Among 53 paired-evaluable patients, ≥CR increased from 18.9% before ASCT to 60.4% after ASCT, while ≥VGPR from 52.8% to 83.0%; 67.9% experienced response deepening. In diagnosis-anchored analyses, ASCT was associated with significantly longer progression-free survival (PFS) (median, 39.4 vs. 12.1 months; p<0.001) and overall survival (OS) (median, 71.4 vs. 40.3 months; p=0.020); however, when ASCT was modeled as a time-dependent covariate and adjusted for baseline covariates, neither PFS (HR, 0.63; p=0.122) nor OS (HR, 0.78; p=0.463) remained statistically significant, indicating that the apparent survival advantage should be regarded as hypothesis-generating. Early post-transplant mortality was 5.5%, and non-relapse mortality was 3.6%. Durable dialysis discontinuation occurred in 16.4% and 12.9% of the ASCT and non-ASCT groups, respectively (p=0.611). Conclusion: In transplant-eligible patients with DDMM, ASCT was feasible and was associated with substantial deepening of response. After accounting for immortal time bias, the apparent survival advantage was attenuated and should be regarded as hypothesis-generating, warranting confirmation in prospective studies.