Salvage Autologous or Allogeneic Stem Cell Transplantation After the Failure of First Autograft in Patients with Multiple Myeloma.

Almost all patients with multiple myeloma (MM) who receive autologous hematopoietic stem cell transplantation (auto HCT) eventually relapse. The treatment options for these patients include novel agents or second (salvage) auto or allogeneic (allo) HCT. Use of reduced intensity conditioning (RIC) has significantly reduced the transplant-related mortality (TRM) with allo HCT. We evaluated the outcomes of patients who received salvage auto or allo HCT for relapsed MM.

Sixty-two patients (24 females and 38 males), with a median age of 55 years (range: 37-73) received a salvage auto HCT between January 1992 and December 2008, whereas 44 patients (19 females and 25 males), with a median age of 51 years (range 32-65) received salvage allo HCT (12 unrelated and 32 related donor) between October 1988 and December 2006. Among 12 patients with unrelated allo HCT, ten were matched at 10/10 HLA loci, while two patients were mismatched at 1 or 2 loci, respectively. Among 32 patients with related donor allo HCT, 29 matched at 10/10 loci, while 3 patients had one or two antigen mismatches. In the allo HCT group eight patients received myeloablative regimens (MA), while thirty six patients received RIC regimens. MA regimens were fludarabine + melphalan 180 mg/m² in 4 patients, busulfan + cyclophosphamide in 2 patients, busulfan + melphalan in one patient and TBI-based in another patient. RIC regimens were fludarabine + melphalan ≤140 mg/m² in 34 patients and cyclophosphamide + fludarabine in 2 patients.

Median follow-up for both auto and allo HCT patients was 24 months. Median prior treatment regimens in auto and allo HCT patients were 4 (2-16) and 5 (2-10), respectively. Overall response rates in evaluable patients in auto HCT and allo HCT were 63% and 75%, respectively. Cumulative incidence of grade II-IV acute GVHD was 27% and limited or extensive chronic GVHD was 43% in allo HCT group. One-hundred day TRM in auto HCT and allo HCT groups was 3% and 9%, respectively. Most common causes of nonrelapse mortality were infections (12%) in auto, and acute or chronic GVHD (24%) in allo HCT group. Median progression free survival (PFS) and overall survival (OS) for auto HCT were 15.5 and 43.3 months, and for allo HCT were 6.9 and 14 months, respectively. Patients receiving MA regimens had significantly shorter PFS and OS than patients receiving RIC regimens.

Both second auto and allo HCT are feasible for salvage therapy in patients with advanced MM, who had relapsed after an auto HCT. Disease progression remains the major cause of treatment failure. RIC regimens have improved the outcome of allo HCT.

No relevant conflicts of interest to declare.