Outcomes of melphalan 140 mg/m2 followed by autologous stem cell transplantation in multiple myeloma patients with co-morbidities: Single-centre experience

High-dose melphalan followed by stem cell rescue is the standard consolidative therapy for transplant-eligible patients with multiple myeloma (MM) in the United Kingdom. A melphalan dose of 200 mg/m2 (Mel200) is considered the "gold standard" for autologous stem cell transplant (ASCT) conditioning for fit patients ≤70 years old; however, with a peak diagnosis incidence at 80-89 years old in the UK dose adjustments will be inevitable to limit toxicities. In this single-centre UK-based retrospective analysis, data was collected from patients with plasma cell dyscrasias who underwent a first reduced-intensity, Mel140, ASCT from 2006 to 2019, a total of 81 patients. We found that the procedure was overall safe with seven (9%) of patients requiring ITU admission and a single transplant-related death within the initial autograft admission. The progression-free survival (PFS) and overall survival were comparable with those previously reported in the literature with median PFS for our cohort of 31 months. Univariate analysis of our data showed an inferior PFS for patients aged ≥70 years. In conclusion, although this is a retrospective analysis, it demonstrates that dose-reduced melphalan conditioning is safe and effective in patients deemed unfit for standard-intensity conditioning.