Reduced-Dose Melphalan (140 or 100 mg/m2) Maintains Efficacy and Tolerability for Multiple Myeloma Patients with Advanced Age or Renal Impairment Undergoing Auto-HCT

Background Melphalan 200 mg/m2 (MEL 200) is standard conditioning for autologous transplant (auto-HCT) in multiple myeloma (MM). Melphalan 140 or 100 mg/m2 (MEL 140/100) is given to patients with advanced age or renal dysfunction. Prior comparisons of MEL 200 versus MEL 140/100 raised concerns about reduced efficacy with MEL 140/100. However, those studies took place prior to the era of induction and post-auto-HCT maintenance with novel agents. We asked whether a diverse, unselected MM cohort treated with novel agents maintains the full benefit of auto-HCT from MEL 140/100. Methods We reviewed 55 consecutive auto-HCT episodes for MM and amyloidosis patients treated with proteasome inhibitors (PI) and/or immunomodulators (IMiD) followed by MEL 200 (n = 30), MEL 140 (n = 20), and MEL 100 (n = 5) from 2006 to 2018. Patients with age u003e 70 or reduced renal function, Karnofsky score, or cardiopulmonary function received MEL 140/100. We analyzed pre-auto-HCT prognostic factors. We examined post-transplant toxicities and disease control. Statistical analyses were performed with SPSS25. Results Female and non-Caucasian patients were well-represented. Pre-transplant therapy was similar. MEL 140/100 trended towards older age and worse Karnofsky score; MEL 140/100 had significantly worse HCT-CI, ISS stage, and renal function (GFR Conclusion MM patients with higher ISS and HCT-CI scores tolerated auto-HCT with MEL 140/ 100 conditioning, Post-transplant outcomes were indistinguishable. Conditioning with MEL 140/100 has equivalent safety and efficacy for patients who are not candidates for MEL 200.