Successful outcome following allogeneic hematopoietic stem cell transplantation in adults with primary immunodeficiency.

The primary immunodeficiencies (PIDs), rare inherited diseases characterized by severe dysfunction of immunity, have been successfully treated by allogeneic hematopoietic stem cell transplantation (Allo-HSCT) in childhood. Controversy exists regarding optimal timing and use of Allo-HSCT in adults, due to lack of experience and previous poor outcomes. Twenty-nine consecutive adult patients, with a mean age at transplant of 24 years (range, 17-50 years), underwent Allo-HSCT. Reduced-intensity conditioning (RIC) included fludarabine (Flu)/melphalan/alemtuzumab (n = 20), Flu/busulfan (Bu)/alemtuzumab (n = 8), and Flu/Bu/antithymocyte globulin (n = 1). Stem cell donors were matched unrelated donors or mismatched unrelated donors (n = 18) and matched related donors (n = 11). Overall survival (OS), event-free survival, transplant-related mortality (TRM), acute and chronic graft-versus-host disease incidence and severity, time to engraftment, lineage-specific chimerism, immune reconstitution, and discontinuation of immunoglobulin replacement therapy were recorded. OS at 3 years for the whole cohort was 85.2%. The rarer PID patients without chronic granulomatous disease (CGD) achieved an OS at 3 years of 88.9% (n = 18), compared with 81.8% for CGD patients (n = 11). TRM was low with only 4 deaths observed at a median follow-up of 3.5 years. There were no cases of early or late rejection. In all surviving patients, either stable mixed chimerism or full donor chimerism were observed. At last follow-up, 87% of the surviving patients had no evidence of persistent or recurrent infections. Allo-HSCT is safe and effective in young adult patients with severe PID and should be considered the treatment of choice where an appropriate donor is available.

HLA-mismatched unrelated donors are a viable alternate graft source for allogeneic transplantation following alemtuzumab-based reduced-intensity conditioning.

The impact of human leukocyte antigen (HLA) mismatch after reduced-intensity conditioning allogeneic hematopoietic stem cell transplantation (RIT) using unrelated donors (UD) is unclear, and may be modulated by T-cell depletion. We therefore examined outcomes of 157 consecutive patients undergoing RIT after uniform conditioning with fludarabine, melphalan, and alemtuzumab (FMC). Donors were 10/10 HLA-matched (MUDs, n = 107) and 6 to 9/10 HLA-matched (MMUDs, n = 50), with no significant differences in baseline characteristics other than increased cytomegalovirus seropositivity in MMUDs. Rates of durable engraftment were high. Graft failure rates (persistent cytopenias with donor chimerism) were similar (8% vs 3%, P = .21), though rejection (recipient chimerism) was more frequent in MMUDs (8% vs 0%, P < .01). There were no significant differences between donors in the incidences of acute graft-versus-host disease (GVHD; 20% vs 22% grade 2-4, respectively, P = .83), chronic extensive GVHD (3-year cumulative incidence [CI] 23% vs 24%, P = .56), or treatment-related mortality (1-year CI 27% vs 27%, P = .96). Furthermore, there was no difference in 3-year overall survival (OS; 53% vs 49%, P = .44). Mismatch occurred at the antigenic level in 40 cases. The outcome in these cases did not differ significantly from the rest of the cohort. We conclude that RIT using HLA-mismatched grafts is a viable option using FMC conditioning.

Incidence and dynamics of Epstein-Barr virus reactivation after alemtuzumab-based conditioning for allogeneic hematopoietic stem-cell transplantation.

BACKGROUND: Reactivation of Epstein-Barr virus (EBV) infection and posttransplant lymphoproliferative disorder (PTLD) pose a significant risk after T-cell-depleted (TCD) allogeneic hematopoietic stem-cell transplantation (HSCT). The pattern of EBV reactivation in patients receiving allogeneic HSCT, incorporating in vivo or in vitro alemtuzumab as the method of TCD, is not known. METHODS: Monitoring for EBV DNA was performed by quantitative polymerase chain reaction on whole blood in 111 consecutive adults undergoing HSCT using alemtuzumab-based TCD. Patients with more than 40,000 copies/mL were screened for PTLD, followed by the withdrawal of immunosuppression and a single infusion of rituximab. RESULTS: The 2-year cumulative incidence of EBV DNAemia was 40.3%. In vivo alemtuzumab was associated with earlier EBV reactivation than in vitro alemtuzumab (100-day incidence 22.7% vs. 2.8%, P=0.006). Eighteen patients (16%) had EBV DNAemia of more than 40,000 copies/mL. In evaluable patients, the initial rate of increase in EBV DNA levels was significantly faster in those who went on to treatment with rituximab than in patients who were left untreated (mean doubling time 3.5 days vs. 4.2 days, P=0.003). Rituximab treatment induced rapid declines in EBV DNA with an average half-life of 1.2+/-0.7 days. Only one patient (0.9%) had histologic confirmation of PTLD and subsequently attained a complete remission with rituximab that persists at 18 months. CONCLUSIONS: Alemtuzumab-based TCD is associated with a high frequency of EBV reactivation but a low (<1%) risk of PTLD using a strategy of preemptive rituximab therapy.