Long-term outcome after allogeneic stem-cell transplantation with reduced-intensity conditioning in patients with multiple myeloma

This study examines the long-term outcomes of a cohort of patients with myeloma who were treated with reduced-intensity conditioning (RIC) regimens after a minimum follow-up of 5 years at our centre. A total of 53 patients with multiple myeloma (MM) who received allogeneic hematopoietic stem-cell transplantation (Allo-SCT) between January 2000 and January 2007 were identified. The median follow-up of living patients was 84 months (51-141). The median age of the MM patients was 50 (28-70) years. Fifty-one patients (96%) received a transplant from a sibling donor. The median time between diagnosis and Allo-SCT was 34 months (6-161), and the median time between auto-SCT and Allo-SCT was 10 months (1-89). Fifty-one patients (96%) received at least one auto-SCT; 24 patients (45%) received a tandem auto-Allo-SCT. At last follow-up, 21 patients (40%) are alive >5 years post RIC Allo-SCT. At last follow-up, 14 (26%) are in first complete remission (CR), and four patients (8%) in second CR after donor lymphocyte infusion or re-induction with one of the new anti-myeloma drugs (bortezomib or lenalidomide) after Allo-SCT. Eight patients (38%) among these long survivors received one of these new drugs as induction or relapse treatment before Allo-SCT. Disease status and occurrence of cGvHD were significantly associated with progression-free survival (PFS); hazard ratio (HR)=0.62 (0.30-1.29, P=0.20). Acute GvHD was correlated with higher transplant-related mortality; HR=4.19 (1.05-16.77, P=0.04). No variables were associated with overall survival (OS). In conclusion, we observe that long-term disease control can be expected in a subset of MM patients undergoing RIC Allo-SCT. After 10 years, the OS and PFS were 32% and 24%, respectively. The PFS curve after Allo-SCT stabilizes in time with a plateau after 6 years post Allo-SCT.