High dose melphalan (HDM) is superior to cyclophosphamide plus etoposide and busulfan (CVB) as the conditioning regimen in autologous stem cell transplantation for multiple myeloma

Objective To compare the efficacy, response and survival between high-dose melphalan (HDM) and cyclophosphamide+ etoposide+ busulfan (CVB) as the conditioning regimen in autologous stem cell transplantation (ASCT) for newly diagnosed multiple myeloma (NDMM) . Methods Retrospectively enrolled 123 consecutive NDMM patients who had received PAD induction with subsequent ASCT from Jan 2011 to Aug 2017. The CVB group and HDM group had 82 and 41 patients respectively. Results ①No differences existed between these 2 groups in non-hematological side effects. ②Patients of CVB group had faster neutrophil and platelet engraftment time, with the median neutrophil engraftment time of 10 (9-35) day vs 11 (9-12) day for patients of HDM group (z=-3.433, P=0.001) , and with median platelet engraftment time of 11 (7-55) day vs 13 (10-35) day for patients of HDM group (z=-3.506, P<0.001) . CVB group entered neutropenia and severe thrombocytopenia more earlier than the HDM group, resulting similar neutropenia duration and severe thrombocytopenia duration between the CVB group and HDM group. However, patients of CVB group had significantly longer fever persistent time and antibiotic administration time. ③The response rate was significantly lower in patients of CVB group vs. patients of HDM group (9/46 vs 14/28, P=0.021) . Further, the minimal residual disease (MRD) negative rate at 3rd month post-transplantation seemed to be lower in CVB group than that in HDM group (31.7%vs 48.8%, P=0.065) . ④Both the univariate and multivariate analysis showed that HDM and CVB groups had similar duration to progression (TTP) (P=0.619) and overall survival (OS) (P=0.295) . Conclusion HDM conditioning regimen is superior to CVB regimen in hematological side effects, tumor burden reduction and administration convenience. However, these two regimen had similar TTP and OS in MM patients receiving ASCT. Key words: Multiple myeloma; Autologous stem cell transplantation; Conditioning