Second Autologous or Allogeneic Transplantation after the Failure of First Autograft in Multiple Myeloma.

Background: Most patients undergoing high-dose therapy and autologous transplant for multiple myeloma eventually relapse. The optimal salvage treatment for these patients is not very well defined. Both autologous and allogeneic hematopoietic stem cell transplantations have been used for salvage. We analyzed the outcomes of second autologous or allogeneic transplants, performed as salvage in patients relapsing after an autograft.

Methods: Fourteen patients received a second autograft for salvage, while thirty-four patients underwent allogeneic transplantation (related 24, unrelated 10). The median age at transplant was 52 years in the autologous group, and 51 years in the allogeneic group. The median interval between the first and the second transplant was 25 months in the autologous group and 17 months in the allogeneic group. The disease characteristics were similar in both autologous and allogeneic groups.

Results: With a median follow-up of 10 months among survivors in each group, both autologous and allogeneic transplant groups had a response rate (complete + partial) of 64%. One hundred day nonrelapse mortality was 7% in the autologous group and 12% in the allogeneic group. Median disease-free survival (DFS) was 11 months in the autologous and 6 months in the allogeneic group. Median overall survival (OS) was 29 moths in the autologous and 14 months in the allogeneic group. 1-year DFS was 40% in the autologous group and 22% in the allogeneic group (p = 0.2). 1-year overall survival was 70% in the autologous and 53% in the allogeneic group (p = 0.3). The most common causes of non-relapse mortality were graft vs. host disease (62%) in the allogeneic group, and infections (100%) in the autologous group. On univariate analysis for DFS in allogeneic group, an interval of >1 year between the first and the salvage transplant was the only factor associated with a significantly better outcome (p = 0.01). Disease status at transplant, type of donor, tumor mass, β₂ microglobulin level, and serum albumin level did not show any impact on the outcome.

Conclusions: Both autografting and allografting are feasible as salvage for myeloma patients relapsing after the first autograft. A slightly better outcome with salvage autografting may be due to decreased toxicity.