RESUMEN
Single-agent high-dose melphalan (Mel) followed by autologous stem cell transplantation (ASCT) remains a standard of care in eligible patients with multiple myeloma (MM), and efforts to improve transplant outcomes by intensifying transplant conditioning have mostly failed. Bendamustine combines both alkylating and antimetabolite properties, can induce responses in MM resistant to other alkylators and represents a promising agent to combine with Mel prior to ASCT. We performed a phase II study to test the safety and efficacy of the high-dose chemotherapy combination of bendamustine, etoposide, cytarabine, and melphalan (BeEAM) in newly diagnosed MM patients up to 70 years of age. The primary study endpoint was the day 100 complete response rate. Sixty-five patients with a median (range) age of 59 (40-69) years underwent transplantation from 2015 to 2020. Other characteristics included Karnofsky performance status <80%, hematopoietic cell transplantation-comorbidity index ≥3, International Staging System III, and high-risk fluorescein in situ hybridization (FISH) in 35%, 46%, 26%, and 44%, respectively. ASCT after BeEAM was well tolerated, and there were no non-relapse deaths through 1 year after transplantation. Although at least 1 nonhematologic grade 3 toxicity was reported in 58 (89%) patients (including grade 3 febrile neutropenia in 48% and stomatitis/esophagitis in 28%), there were no grade ≥3 renal or hepatic toxicity and no grade ≥4 non-hematologic toxicity. The day 100 response rate was ≥CR1 and ≥ very good partial response (VGPR1) in 40% and 89%, respectively. With a median follow-up of 44 (13-70) months, the 3-year overall survival was 92%, 96%, and 90% for all patients and those with standard- and high-risk FISH, respectively. The corresponding values for 3-year progression-free survival was 57%, 72%, and 40%, respectively. When BeEAM-conditioned patients were compared to historical Mel-conditioned cohort, no significant differences were noted in relapse or survival outcomes in univariate or multivariable analysis. In summary, BeEAM was shown to be a safe and effective conditioning regimen before up-front autologous transplant for MM. Although the BeEAM regimen does not appear to offer a significant advantage over single-agent Mel, further studies combining bendamustine and melphalan in the front-line setting may be warranted.
