Propylene glycol-free melphalan (PG-free MEL) does not improve complications or outcomes after autologous stem cell transplantation (ASCT) among patients with multiple myeloma, according to a study published in Nature.

High-dose melphalan is a frequently used component of conditioning regimens for ASCT in MM, but is associated with high rates of adverse events such as nausea, vomiting, diarrhea, and gastrointestinal mucositis. PG-free MEL, a novel formulation, improved the stability and solubility of melphalan and may improve efficacy and toxicity compared to the original formulation.

For this retrospective study, researchers analyzed the outcomes of 416 patients with MM who underwent ASCT, 200 of whom received PG-solubilized MEL and 216 who received PG-free MEL. Baseline characteristics were well-balanced between the 2 study arms.

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Results showed that after stem cell infusion (Day 0), there were no significant differences in the rate of hospitalization between the 2 treatment arms; 42% and 29% of patients in the PG-free MEL and PG-solubilized MEL groups, respectively, required hospitalization (P < .49). No significant differences in the median length of hospital stay, rates of febrile neutropenia, required intravenous granisetron, grade 2 or worse oral/esophageal mucositis, intravenous fluid replacement, or narcotic requirement, were observed.

Patients who received PG-free MEL had a significantly higher incidence of mostly C. dificile-negative diarrhea compared with patients who received PG-solubilized MEL (82% vs 71%; P = .015).

Furthermore, there were no significant differences between the two study groups in regards to hematologic response after 100 days, and progression-free survival was comparable after a median follow-up of 16.2 months.

Findings of this study show that PG-free MEL may not reduce short-term complications or improve outcomes after ASCT for MM. The authors concluded that “future studies should assess the impact of PG-free MEL on both short- and long-term outcomes in this disease group.”


Miller KC, Gertz MA, Buadi FK, et al. Comparable outcomes using propylene glycol-free melphalan for autologous stem cell transplantation in multiple myeloma [published online August 16, 2018]. Bone Marrow Transplant. doi: 10.1038/s41409-018-0302-6