Early mortality and the retinoic acid syndrome in acute promyelocytic leukemia: impact of leukocytosis, low-dose chemotherapy, PMN/RAR-alpha isoform, and CD13 expression in patients treated with all-trans retinoic acid. Blood

All-trans retinoic acid (RA) has proven a major advance in the treatment of acute promyelocytic leukemia WL). How-ever, the proper management of patients who present with or develop leukocytosis during remission induction with all-trans RA is not established, nor is there a clear relation be-tween leukocytosis and the development of the retinoic acid syndrome. We reviewed the course of our patients who un-derwent induction with all-trans RA to identify potential fac-tors that might predict for the development of this syndrome and to identify which patients, if any, might specifically ben-efit from additional treatment with cytotoxic chemotherapy. Seventy-eight courses of all-trans RA therapy were adminis-tered to patients with a motecular diagnosis of APL. Initial and peak leukocyte counts, their rate of rise, leukocyte count criteria developed in Europe, and cell surface marker expres