STAT5B and acute promyelocytic leukemia: However, in our series, one pediatric patient achieved a second CR after ATO plus ATRA plus intrathecal therapy for a concomitant bone marrow and CNS relapse, suggesting that ATO could be active as well in NPM1-RARα APL; (3) an ATRA plus chemotherapy-based regimen could be employed for TBLR1-RARα and STAT5B-RARα, but the CR rate seems much lower than in PML-RARα APL.