Bortezomib With High-dose Melphalan Conditioning Regimen in Newly Diagnosed Multiple Myeloma Patients: Long-term Follow-up

transplantation (ASCT) is the standard strategy after induction therapy for newly diagnosed transplant-eligible multiple myeloma. High-dose melphalan (HDM) conditioning has been the recommended treatment regimen for a long time. No other conditioning regimen has been proven safer and more effective. Because bortezomib has a synergistic effect with melphalan, bortezomib with HDM (Bor-HDM) as a conditioning regimen has shown favorable outcomes, improved complete response rates after ASCT, and no prolonged hematological toxicities. However, few studies have reported long-term follow-up data. This study aimed to evaluate the long-term progression-free survival (PFS) and overall survival (OS) of patients receiving Bor-HDM conditioning, compared to those treated with HDM alone. Patients and Methods: This single-center retrospective study included 36 patients newly diagnosed with transplant-eligible myeloma from 2008 to 2020. In total, 15 patients received a Bor-HDM regimen, while 21 patients received HDM as a conditioning regimen. The probabilities of PFS and OS were plotted using the Kaplan-Meier method. All statistical analyses were performed using EZR software. Results: After a median follow up of 77 months, no severe hematological toxicities were observed. The PFS and OS rates in the BorHDM group as compared with the HDM group were 0.762 vs. 0.60 (p=0.409) and 0.80 vs. 0.904 (p=0.476) respectively. No significant differences were observed between the two groups. Conclusion: These long-term results show that Bor-HDM is a safe and effective option for ASCT conditioning regimens.