Distinctive features associated with differentiation syndrome in acute promyelocytic leukemia in patients treated by all-trans retinoic acid and arsenic trioxide

In acute promyelocytic leukemia (APL), the combination treatment of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) appears to have a synergistic effect. Due to this synergism, differentiation syndrome (DS) in APL assumes a distinct identity separate from the formerly known ATRA syndrome, with distinct temporal patterns, diagnostic parameters, and clinical behavior. We retrospectively evaluated single-center data of years 2013-2022. Patients with newly diagnosed APL were categorized into three groups (16 patients in ATRA/ATO standard-risk group, 3 patients in ATRA/chemotherapy standard-risk group, and 5 patients in ATRA/chemotherapy high-risk group). Our aim was to analyze leukocytosis, signs of DS, and hepatic impairment within the first 25 days of treatment. The incidence of DS in the ATRA/ATO SR group was 43.8 %, with a median of 4 days and 2 days from ATRA and ATO initiation, respectively. This group also exhibited higher peak levels of leukocytosis 34.5 (6.0-113.4) x10