Analysis of Acute Leukemia-Associated Hemophagocytic Lymphohistiocytosis in Adults: A Single-Center Experience

The clinical features and outcomes of adult acute leukemia (AL)-associated hemophagocytic lymphohistiocytosis (AL-HLH) remain insufficiently characterized. We retrospectively analyzed 45 adult patients diagnosed with AL-HLH between December 2019 and June 2023. Among 746 AL patients, 45 developed HLH, with 40 developing acute myeloid leukemia (AML), 4 developing acute lymphoblastic leukemia (ALL), and 1 developing mixed-phenotype acute leukemia (MPAL). According to the ELN 2022 criteria, 16 (35.6%) had favorable, 3 (6.7%) had interediate, and 26 (57.7%) had poor risk. At the time of HLH onset, seven (15.6%) patients were in composite complete remission (CCR), and 38 (84.4%) were in non-CCR states; 25 (55.6%) patients were newly diagnosed before induction chemotherapy. The HLH-94/04-based regimens (etoposide and dexamethasone) with or without ruxolitinib achieved an ORR (overall remission rate) of 82.2% and a CR rate of 66.7%. After anti-leukemic therapy, 60% (27/45) of patients achieved CCR for leukemia (including patients in CCR at HLH onset and those achieving CCR after treatment). Hematopoietic stem cell transplantation (HSCT) independently predicted sustained remission. The estimated overall rates at 6 and 12 months after HLH diagnosis were 73.1% and 59.2%, respectively. Multivariate Cox analysis identified failure to achieve CCR for leukemia as the only independent adverse prognostic factor. AL-HLH is an uncommon but severe complication that predominantly occurs in AML patients with poor-risk cytogenetics or active disease. Early recognition, effective HLH control, and achievement of CCR in AL are crucial for improving patient prognosis.