Successful All-trans Retinoic Acid Treatment of Acute Promyelocytic Leukemia in a Patient with NPM/RAR Fusion

Acute promyelocytic leukemia (APL) is characterized by a reciprocal chromosomal translocation involving the gene for retinoic acid receptor alpha(RAR). Most APL patients have a t(15;17) translocation that generates the PML-RAR fusion gene, and such patients respond well to treatment with all-trans retinoic acid (ATRA). Some APL cases also involve rearrangements that fuse RAR to partner genes other than PML, including nucleophosmin (NPM), promyelocytic leukemia zinc finger (PLZF), nuclear mitotic apparatus (NUMA), and Stat5b, but the clinical characteristics of APL without PML-RAR have not been fully clarified. We describe a 64-year-old man with NPM-RAR-positive APL who was receiving hemodialysis therapy for chronic uremia. Complete remission was achieved with ATRA monotherapy and was maintained for 18 months with consolidation chemotherapy. These findings suggest that ATRA can be used to treat APL patients with NPM/RAR as well as APL with PML/RAR.