Acute promyelocytic leukemia with isochromosome 17q and cryptic PML-RARA successfully treated with all-trans retinoic acid and arsenic trioxide

Acute promyelocytic leukemia (APL) is a subtype of acute leukemia that is characterized by typical morphology, bleeding events and distinct chromosomal aberrations, usually the t(15;17)(q22;q21) translocation. Approximately 9% of APL patients harbor other translocations involving chromosome 17, such as the t(11;17)(q23;q21), t(5;17)(q35;q12-21), t(11;17)(q13;q21), and der(17). All-trans retinoic acid (ATRA) and arsenic trioxide (ATO) have specific targeted activities against the PML-RARA fusion protein. The combination of ATRA and ATO is reportedly superior to chemotherapy and ATRA as induction therapy for APL. The clinical significance of non-t(15:17) APL-related aberrations is controversial, with conflicting reports regarding sensitivity to modern, targeted therapy. Isochromosome 17q (iso(17q)) is rarely associated with APL and usually occurs concurrently with the t(15:17) translocation. No published data is available regarding the efficacy of ATO-based therapy for APL patients who harbor iso(17q). We report on an APL patient with iso(17q) as the sole cytogenetic aberration and a cryptic PML-RARA transcript, who was treated with ATRA and ATO after failure of chemotherapy and achieved complete remission. To our knowledge, this is the first published report of APL associated with iso(17q) as the sole cytogenetic aberration, which was successfully treated with an ATO containing regimen.