PLZF-RAR, NPM1-RAR, and Other Acute Promyelocytic Leukemia Variants: The PETHEMA Registry Experience and Systematic Literature Review.

It has been suggested that 1-2% of acute promyelocytic leukemia (APL) patients present variant rearrangements of retinoic acid receptor alpha (RARα) fusion gene, with the promyelocytic leukaemia zinc finger (PLZF)/RAR being the most frequent. Resistance to all-trans-retinoic acid (ATRA) and arsenic trioxide (ATO) has been suggested in PLZF/RAR and other variant APLs. Herein, we analyze the incidence, characteristics, and outcomes of variant APLs reported to the multinational PETHEMA (Programa para el Tratamiento de Hemopatias Malignas) registry, and we perform a systematic review in order to shed light on strategies to improve management of these extremely rare diseases.