Comparison of Patient Outcomes with Two Different Formulations of Melphalan As Conditioning Chemotherapy for Autologous Stem Cell Transplantation in Multiple Myeloma

Introduction: High-dose melphalan is the standard conditioning chemotherapy for autologous stem cell transplantation (ASCT) in multiple myeloma (MM). However, patients experience several side effects and toxicities from high-dose melphalan. In 2016, United States Food and Drug Administration approved Evomela, a propylene glycol-free formulation of melphalan, as conditioning chemotherapy for ASCT in MM. This was based on its bioequivalence to the standard propylene-glycol solubilized melphalan formulation (Alkeran) in a phase 2 study. Evomela has the advantages of improved solubility, stability, bioavailability and being free of propylene glycol that is associated with organ dysfunction.

Methods: We conducted a retrospective study of patients who received ASCT with high dose chemotherapy using alkeran (n=255) or evomela ( n=259) at our institution to compare their outcomes such as side effects, duration of cytopenias, transfusion requirements, length of hospital stay, readmission within 30 days and progression-free survival (PFS) post-SCT. Clinical and demographic characteristics were compared between two treatment regimens using the Chi-square test for categorical variables and the Wilcoxon rank sum test for the continuous variables. Overall survival (OS) was calculated from the date of transplant to death, censoring the alive patients at their last follow up date. Progression-free survival (PFS) was calculated from the date of transplant to date of relapse or death, whichever occurred first, censoring at the last follow-up if no relapse or death. OS and PFS estimates were calculated using the Kaplan-Meier method and compared using the log-rank test.

Results: The baseline patient characteristics such as age, ISS stage, comorbidity index and number of prior lines of therapy prior to ASCT were similar between the two groups. (See table 1). Mucositis was seen in 77.2% of the patients who received Alkeran compared to 69.5% who received Evomela (p=<0.001). Incidence of febrile neutropenia was 65.9% in the Alkeran group and 49.4% in the Evomela group (p=0.0002). Chemotherapy-induced nausea and vomiting were reported in 98.8% and 93.4% of the patients in the Alkeran and Evomela groups respectively (p=0.001). Rates of diarrhea and clostridium difficile infection were similar with the two drugs. Time to neutrophil engraftment was the same in both the groups while duration of thrombocytopenia (platelets <20k) was slightly longer in the Evomela group (6 days in alkeran and 8 days in evomela group, p=<0.001). Red cell transfusion requirement was higher with the use of Alkeran compared to Evomela (42.3% vs 21.8%, p=0.001) while platelet transfusion was the same. There was no difference in the duration of hospital stay between the two groups. However, rate of readmission within 30 days of discharge was higher in patients who got Evomela compared to Alkeran (9.4% versus 17.4%, p=0.008). Day +100 serological response (very good partial response or better), PFS post-SCT and OS were similar in both groups. (Figure 1).

Conclusion: We conclude that use of Evomela is associated with a better side-effect profile and transfusion requirement while having similar outcomes as Alkeran.