Comparative efficacy of donor lymphocyte infusions in augmenting graft-versus-leukemia effect after allogeneic hematopoietic stem cell transplantation for patients with myeloid malignancies

Background: The efficacy of donor lymphocyte infusions (DLI) among various myeloid malignancies (particularly, genetic subtypes) and the optimal timing of DLI initiation remains unclear. Methods: This was a retrospective study of 62 patients with myeloid malignancies treated with an alloHSCT and DLI from years 2001-2022. DLI indication was therapeutic 55 (89%), pre-emptive 6 (10%) and prophylactic 1 (2%) with complete remission (CR/CRi) in twenty patients with common diagnoses being 9 (45%) acute myeloid leukemia, 6 (30%) myelodysplastic syndromes, and 3 (15%) chronic myelomonocytic leukemia among others. Results: Among patients who received therapeutic DLI (n=55), the best response was CR/CRi in 16 (29%) patients. At a median follow-up from the date of DLI of 75 (95% CI 35-121) months, there were 49 (79%) deaths with a median OS of 6 (95% CI 4-14) months, higher in patients in CR/CRi versus no CR/CRi (median 51 versus 4 months, P=0.008). Presence of cytogenetic abnormalities such as complex karyotype, deletions in chromosome 5, 7 and 17p, and mutations in TP53, KRAS, NRAS, RUNX1 or JAK2 were associated with adverse outcomes. Conclusion: DLI is an effective treatment strategy for post-transplant relapse of all myeloid malignancies, with specific genetic subtypes showing poorer outcomes and survival.