Autologous Hematopoietic Stem Cell Transplantation in Multiple Myeloma in the Era of New Drugs

Background & Aims. The present retrospective single-center study analysed the impact of high-dose chemotherapy with melphalan with subsequent autologous hematopoietic stem cell transplantation (auto-HSCT) on survival in multiple myeloma (MM) in the era of new induction regimens. Materials & Methods. The clinical trial included 133 MM patients aged from 31.2 to 78.2 years (the median age was 55.3 years). There were 66 female and 67 male patients. Bortezomib-based regimens as first-line treatment were administered in 133 MM patients, 74 of them received high-dose chemotherapy with melphalan and either single (n = 25), or double (n = 49) auto-HSCT as consolidation therapy in the period from 2006 to 2016. Results. The overall 5-year survival (OS) rates were 86.5 % for the auto-HSCT treated group vs. 72.9 % for the non-auto-HSCT treated group (p = 0.03); 5-year progression-free survival (PFS) rates were 64.9 vs. 39 % for the auto-HSCT and non-auto-HSCT treated groups, respectively (p = 0.0016). MM relapse/progression occurred more frequently in the non-auto-HSCT treated patients (52.5 vs. 28.4 %; p = 0.0016). In multivariate analysis the age above 60 was determined as prognostic factor of lower PFS and increase in relapse/progression rate (p = 0.004 and p = 0.04, respectively). The variant of monoclonal protein (Bence-Jones myeloma) was determined as prognostic factor of higher OS and decrease in relapse/progression rate (p = 0.02 and p = 0.04, respectively). Complete nonresponsiveness to induction therapy has proved to be an independent predictor of both poor OS and PFS (p = 0.04 and p = 0.041, respectively). 2-year bortezomib-based maintenance therapy following the auto-HSCT treatment resulted in a statistically significant improvement in 5-year PFS (67.4 vs. 60.7 %; p = 0.03) and a decrease in relapse/progression frequency (26.1 vs. 32.1 %; p = 0.05). Conclusion. High-dose chemotherapy with melphalan with subsequent auto-HSCT is an effective MM treatment strategy, and a subsequent long-term maintenance therapy results in a PFS improvement and a decrease in relapse/progression frequency.