Autologous stem cell transplantation (ASCT) represents a potentially curative treatment option for patients with multiple myeloma (MM). ASCT has improved overall and event-free survival when compared with chemotherapy alone.1,2 Once diagnosed with MM, patients can be stratified by risk based on their chromosomal abnormalities using fluorescence in situ hybridization (FISH), which helps determine if the patient is a potential ASCT candidate.3 Determining ASCT eligibility is complicated process that varies from transplant center to transplant center and includes multiple factors such as age, presence of cirrhosis and/or congestive heart failure, and performance status.
Prior to undergoing an actual ASCT, patients with MM typically receive a “conditioning regimen” of chemotherapy or total body irradiation (TBI) that aims to reduce the overall tumor burden as well as prevent potential graft rejection via high-dose immunosuppression.4 Conditioning regimens can be classified based on their overall immunosuppressive intensity including myeloablative (high dose), reduced intensity and nonmyeloablative.4
Busulfan is a common chemotherapeutic agent used in the high-dose conditioning regimens and it works as an alkylating agent. Busulfan has been used in combination with other agents such as cyclophosphamide, fludarabine, and melphalan. Similarly to busulfan, melphalan is also an alkylating agent.
Melphalan has been used as a single-agent conditioning regimen at a dose of 200 mg/m2 (MEL200). 5,6 In addition, low-dose melphalan has also been used in combination with busulfan (BUMEL) in attempts of limiting toxicities while improving MM outcomes.5,6