Finding the Sweet Spot for Donor Lymphocyte Infusions

In this issue of Biology of Blood and Marrow Trans-plantation, Krishnamurthy et al. [1] report very favorableclinical outcomes after preemptive donor lymphocyte infu-sion (pDLI) or therapeutic donor lymphocyte infusion (tDLI)in patients with low levels of donor chimerism or relapseddisease, respectively, after allogeneic hematopoietic stemcell transplantation (HSCT). Patients were conditioned withregimens containing alemtuzumab or antithymocyte glob-ulin, producing in vivo T cell depletion (TCD). Thirty-two of62 patients (52%) received pDLI within 6 months, and thesepatients had a 5-year overall survival of 80% and an event-free survival of 65%. Fifty-one patients with relapsed orpersistent disease who received tDLI had a 5-year overallsurvival of 40%. Survival was better in patients who receivedtDLI at more than 6 months after HSCTcompared with thosewho did so at less than 6 months after HSCT.Thesurprisingresultsfromthisstudy,inwhichmorethanhalf of the patients received pDLI within 6 months afterundergoing HSCT, are the relatively low incidence of graft-versus-host disease (GVHD; 31% after pDLI versus 45% aftertDLI) and the low rate of GVHD-related deaths (3% after pDLIversus2%aftertDLI).Furthermore,only7deaths(11%)duetodisease relapse occurred in the patients who received pDLI,despite the low number of donor T cells in the DLI (mediandose, 1.5 10