Outcome of Patients With IgD and IgM Multiple Myeloma Undergoing Autologous Hematopoietic Stem Cell Transplantation: A Retrospective CIBMTR Study

IntroductionImmunoglobulin D (IgD) and IgM multiple myeloma represent uncommon immunoglobulin isotypes, accounting for 2% and 0.5% of cases, respectively. Limited information is available regarding the prognosis of these isotypes, but they have been considered to have a more aggressive course than the more common immunoglobulin G (IgG) and IgA isotypes. In particular, the outcome after autologous hematopoietic stem cell transplantation (auto-HCT) has not been well defined.Patients and MethodsUsing the Center for International Blood and Marrow Transplant Research (CIBMTR) database, we identified 36 patients with IgD and 11 patients with IgM myeloma among 3578 myeloma patients who received intensive therapy and auto-HCT over a 10-year period.ResultsThe progression-free and overall survival probabilities at 3 years were 38% (95% CI, 21%-56%) and 69% (95% CI, 51%-84%) for IgD myeloma, and 47% (95% CI, 17%-78%) and 68% (95% CI, 36%-93%), respectively, for IgM disease. Although formal statistical analysis was limited by the small sample size, these results were comparable to those for IgG and IgA patients autografted during the same time period. Transplantation-related mortality and disease relapse/progression of myeloma were also similar for all isotypes.ConclusionThis analysis demonstrates comparable outcomes in all immunoglobulin isotypes. Therefore, auto-HCT should be offered to eligible patients with IgD and IgM myeloma.