Time to unrelated donor leukocyte infusion is longer, but incidence of GVHD and overall survival are similar for recipients of unrelated DLI compared to matched sibling DLI.

Donor leukocyte infusion (DLI) is used to treat relapsed leukemia after allogeneic hematopoietic stem cell transplant (HCT). Data comparing outcomes after unrelated DLI (uDLI) to matched sibling DLI (msDLI) are scant. We performed a retrospective analysis to assess differences in time to administer uDLI versus msDLI, and impact on outcomes. Fifty three patients with relapsed acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), or myelodysplastic syndrome (MDS) after allogeneic HCT received uDLI (n = 18) or msDLI (n = 35) from 2000 to 2011. Median time from relapse to uDLI request was 15 days (range 0-66). Median time from relapse to uDLI was 56 days versus 40 days for msDLI patients (p = 0.034). 35% of msDLI and 44% of uDLI patients developed acute GVHD (p = 0.50). There was no significant difference in Grade C/D GVHD among uDLI and msDLI (28% and 21%, p = 0.58) or median OS after DLI between uDLI and msDLI (95 versus 75 days, p = 0.76). For patients with relapsed acute leukemia and MDS after allogeneic HCT, time from relapse to uDLI was longer than to msDLI, but incidence of GVHD and overall survival were similar. Access to uDLI does not appear to be a barrier to DLI administration. Outcomes unfortunately remain poor regardless of donor source.

Early donor chimerism levels predict relapse and survival after allogeneic stem cell transplantation with reduced-intensity conditioning.

The success of hematopoietic stem cell transplantation (HSCT) with reduced-intensity conditioning (RIC) is limited by a high rate of disease relapse. Early risk assessment could potentially improve outcomes by identifying appropriate patients for preemptive strategies that may ameliorate this high risk. Using a series of landmark analyses, we investigated the predictive value of early (day-30) donor chimerism measurements on disease relapse, graft-versus-host disease, and survival in a cohort of 121 patients allografted with a uniform RIC regimen. Chimerism levels were analyzed as continuous variables. In multivariate analysis, day-30 whole blood chimerism levels were significantly associated with relapse (hazard ratio [HR] = .90, P < .001), relapse-free survival (HR = .89, P < .001), and overall survival (HR = .94, P = .01). Day-30 T cell chimerism levels were also significantly associated with relapse (HR = .97, P = .002), relapse-free survival (HR = .97, P < .001), and overall survival (HR = .99, P = .05). Multivariate models that included T cell chimerism provided a better prediction for these outcomes compared with whole blood chimerism. Day-30 chimerism levels were not associated with acute or chronic graft-versus-host disease. We found that high donor chimerism levels were significantly associated with a low lymphocyte count in the recipient before transplant, highlighting the impact of pretransplant lymphopenia on the kinetics of engraftment after RIC HSCT. In summary, low donor chimerism levels are associated with relapse and mortality and can potentially be used as an early predictive and prognostic marker. These findings can be used to design novel approaches to prevent relapse and to improve survival after RIC HSCT.