Efficacy of Azacitidine and Prophylactic Donor Lymphocyte Infusion after HSCT in Pediatric Patients with Acute Myelogenous Leukemia: A Retrospective Pre-Post Study

Abstract

Pediatric patients with acute myeloid leukemia (AML) who undergo allogeneic hematopoietic stem cell transplantation (HSCT) continue to have high rates of relapse. In 2018, Phoenix Children's Hospital started using post-HSCT maintenance therapy in patients with AML in attempt to decrease the number of relapses after HSCT. This therapy consisted of the hypomethylating agent azacitidine (AZA; 6 cycles starting on day +60) and prophylactic donor lymphocyte infusion (DLI; 3 escalating doses beginning after day +120). We aimed to compare 2-year leukemia-free survival (LFS) post-HSCT between patients with AML who received post-HSCT maintenance therapy with AZA and prophylactic DLI and historical control patients who did not receive post-HSCT therapy. This retrospective pre-post study was conducted at Phoenix Children's Hospital and included patients with AML who underwent HSCT between January 1, 2008, and May 31, 2022. We compared LFS, overall survival (OS), and immune reconstitution patterns post-HSCT between patients with AML who received post-HSCT maintenance therapy with AZA and prophylactic DLI (postintervention group) and historical control patients who did not receive this post-HSCT maintenance therapy (preintervention group). Sixty-three patients were evaluable. After excluding 7 patients who died or relapsed prior to day +60, 56 patients remained, including 39 in the preintervention group and 17 in the postintervention group. The median age at transplantation was 9.1 years in the preintervention group and 11 years in the postintervention group (P=.33). The 2-year LFS was 61.5% in the preintervention group, compared to 88.2% in the postintervention group (P=.06). The 2-year OS was 69.2% in the preintervention group and 88.2% in the postintervention group (P=.15). The rates of CD3+CD4+ T cell and CD19+ B cell recovery were faster in the preintervention group compared to the postintervention group (P = .004 and .0006, respectively). In this limited retrospective study, post-HSCT maintenance therapy using AZA and prophylactic DLI was well tolerated; however, its efficacy is yet to be fully determined.