Autologous stem cell transplantation for multiple myeloma: Long-term results.

Background: Survival of myeloma patients has improved considerably in the past decade. However, limited data are available on their long-term outcome. We analysed the data of 225 consecutive patients who underwent autologous stem cell transplantation (ASCT) at our centre.
Methods: Between April 1990 and December 2013, a total of 225 patients with multiple myeloma (median age 53 years, range 27-67 years, 69.3% men) underwent ASCT. High-dose melphalan 200 mg/m2 was used for conditioning. Before transplant, the patients received induction therapy with novel agents (thalidomide and dexamethasone, or lenalidomide and dexamethasone, or bortezomib and dexamethasone); or vincristine, doxorubicin, dexamethasone; or alkylating agents (vincristine, melphalan, cyclophosphamide and prednisolone; or melphalan and prednisolone). The response to transplant was evaluated using the European Bone Marrow Transplant criteria, and an intention-to-treat analysis was done.
Results: Four-fifths (79.6%) of our patients had Durie Salmon Stage (DSS) IIIA and nearly a quarter (24%) of them had International Stage III disease. Before the transplant, 80.4% of patients had chemosensitive disease. The median interval from diagnosis to transplant was 10 months (range 2-128 months). Following ASCT, 197 (87.5%) patients responded. Complete response was obtained in 54.7%, very good partial response in 19% and partial response in 13.8%. At a median follow-up of 90 months (range 18-266 months), the median progression-free survival (PFS) and overall survival (OS) were 32 and 85.5 months, respectively. The estimated PFS and OS at 10 years were 29.7% and 43.6%, respectively. On multivariate analysis, the presence of extramedullary disease (HR 3.05, p < 0.001), and ISS III (HR 0.50, p < 0.02) predicted inferior OS. Extramedullary disease at diagnosis (HR 1.585, p < 0.03), and more than one regimen pre- transplant (HR 0.53, p < 0.02) predicted an inferior PFS. Complete response was a predictor of superior OS and PFS (p < 0.001).
Conclusion: Complete response following ASCT is associated with good long-term outcome. Alternative treatment strategies are needed to improve results in patients who fail to achieve CR post-transplant and in those with high-risk disease.