Toxicities, response and survival: Autologous stem cell transplantation for multiple myeloma over 25 years at a single center

High-dose melphalan with autologous stem cell transplantation (SCT) has become a pillar of treatment for patients with multiple myeloma (MM). In the early era of SCT for MM, patients received oral alkylators and radiation, potential contributors to myeloid malignancies, while the modern era coincided with the availability of novel agents that have transformed prognosis in MM. To enable those new to the field to appreciate the advances, we conducted a retrospective study of 179 consecutive MM patients who underwent SCT over a 25-year period at our center. We compared patients transplanted from 1988-2000 (early era, n=63) to those from 2001-2012 (modern era, n=116) seeking to identify statistically significant differences. At SCT, early era patients were younger, had a lower BMI, and were more likely to have been treated with oral melphalan and palliative radiation. At SCT, they were also less likely to have VGPR or CR (27.4% vs 50%) and more likely to have stable or relapsed refractory disease (25.9% vs 15.6%). Post-SCT, they had higher treatment-related mortality (9.5% vs 0.8%), and poorer overall survival both after relapse (OS, 1 vs 2.6 years) and in toto (2.8 vs 7.9 years). For both eras, MM status > VGPR at SCT predicted improved OS while exposure to oral melphalan prior to SCT predicted worse OS. Modern era patients were more likely to die of progressive MM and early era patients of infections and acute myeloid leukemia. Collectively, these data highlight the improved outcomes of MM patients undergoing SCT over the past 25 years.