Polyclonal Immunoglobulin Recovery after Autologous Stem Cell Transplantation Is an Independent Prognostic Factor for Survival Outcome in Patients with Multiple Myeloma.

We retrospectively analyzed multiple myeloma (MM) patients who underwent autologous stem cell transplantation (ASCT) without maintenance therapy to assess the impact of recovery of normal immunoglobulin (Ig) on clinical outcomes. The recovery of polyclonal Ig was defined as normalization of all values of serum IgG, IgA, and IgM 1 year after ASCT. Among 50 patients, 26 patients showed polyclonal Ig recovery; 14 patients were in ≥complete response (CR) and 12 remained in non-CR after ASCT. The patients with Ig recovery exhibited a significantly better progression-free survival (PFS, median, 46.8 vs 26.7 months, = 0.0071) and overall survival (OS, median, not reached vs 65.3 months, < 0.00001) compared with those without Ig recovery. The survival benefits of Ig recovery were similarly observed in ≥CR patients (median OS, not reached vs 80.5 months, = 0.061) and non-CR patients (median OS, not reached vs 53.2 months, = 0.00016). Multivariate analysis revealed that non-CR and not all Ig recovery were independent prognostic factors for PFS (HR, 4.284, 95%CI (1.868-9.826), = 0.00059; and HR, 2.804, 95%CI (1.334-5.896), = 0.0065, respectively) and also for OS (HR, 8.245, 95%CI (1.528-44.47), = 0.014; and HR, 36.55, 95%CI (3.942-338.8), = 0.0015, respectively). Therefore, in addition to the depth of response, the recovery of polyclonal Ig after ASCT is a useful indicator especially for long-term outcome and might be considered to prevent overtreatment with maintenance therapy in transplanted patients with MM.