Comparison of Patient Outcomes With Two Different Formulations of Melphalan as Conditioning Chemotherapy for Autologous Hematopoietic Cell Transplantation in Multiple Myeloma

Background: High-dose melphalan (HDM) with autologous hematopoietic cell transplantation (AHCT) after induction chemotherapy is considered standard of care in transplant-eligible patients with newly-diagnosed multiple myeloma (MM). Alkeran melphalan has propylene glycol as a solvent (PG-mel) while Evomela utilizes a propylene glyclol-free formulation (PGF-mel). We evaluated the differences in efficacy and safety of the 2 formulations as there are no prospective head-to-head trials.

Methods: We retrospectively reviewed the medical records of all 259 consecutive MM patients who received PGF-mel as part of HDM-AHCT at The Ohio State University (OSU). The comparator group was the preceding 255 patients who received PG-mel.

Results: Baseline patient characteristics were similar between the 2 groups. Post-AHCT rates of relapse were comparable in the PG-mel and PGF-mel groups. Some adverse events were observed at a higher frequency in the PG-mel group compared to the PGF-mel group (grade ≥ 2 mucositis, febrile neutropenia, other infectious complications, and acute renal insufficiency). Time to neutrophil engraftment was slightly longer in the PG-mel group while time to platelet engraftment was longer in PGF-mel group. Red cell transfusion requirement was higher with the use of PG-mel but not platelet transfusion. Duration of hospitalization was slightly shorter with PGF-mel but readmission rates within 30 days of discharge were higher.

Conclusion: Considering possible confounding factors could possibly account for observed differences in some adverse events, the comparable treatment responses, and difference in cost of the 2 formulation, The OSU reverted to PG-mel as the preferred formulation for HDM-AHCT in MM.