Long-term follow-up of recipients of CD8-depleted donor lymphocyte infusions for the treatment of chronic myelogenous leukemia relapsing after allogeneic progenitor cell transplantation

Donor lymphocyte infusions (DLIs) are an effective treatment for relapsed C hronic myeloid leukemia (CML) after allogeneic transplantation but are limi ted by the occurrence of GVHD. CD8(+)T lymphocytes are involved in the path ogenesis of GVHD but may not be essential for the graft-versus-leukemia (GV L) effect in CML. We have treated 26 CML patients with posttransplantation relapse with CDS-depleted DLI. Thirteen of 15 patients (87%) who relapsed i n early-phase CML achieved complete cytogenetic response, but only 1 of 11 who relapsed in advanced-phase disease achieved complete response. Acute GV HD occurred in 2 patients (8%), and extensive chronic GVHD occurred in 2 pa tients (11%). Treatment-related mortality was 11.5%. Responses were durable ; with a median follow-up of 4.2 years (1-7.5 years), only 1 responding pat ient relapsed (7%). CD8-depleted DLI was equally effective and safe after u nrelated donor transplants and sibling transplants. Cytogenetic clonal evol ution at the time of DLI was not predictive of treatment failure unless ass ociated with hematologic criteria for disease acceleration. CD8 depletion i s an effective method to separate GVL from GVHD for posttransplantation rel apsed CML. This strategy is associated with durable complete remissions and a low rate of complications and therefore merits further investigation in larger-scale comparative trials.