High-Dose Chemotherapy and Stem Cell Transplantation in ZBTB16::RARA Acute Promyelocytic Leukemia: A Case Report

A small proportion of patients with acute promyelocytic leukemia (APL) harbor variant chromosomal translocations that lead to fusion of *RARA* to one of several alternative partner genes. The most frequently reported of variant is the t(11;17)(q23;q21), which generates the fusion of the zinc finger gene *ZBTB16* (formerly PLZF) to the *RARA* locus (*ZBTB16::RARA* fusion). This APL subtype is typically resistant to standard APL-directed therapies and most patients with this translocation relapse within one year with limited subsequent treatment options. Here, we report on a patient with *ZBTB16::RARA* APL who achieved durable molecular complete remission lasting more than two years after high-dose chemotherapy with busulfan and cyclophosphamide followed by autologous stem cell transplantation. This therapeutic approach has not previously been described for this rare APL variant and may represent a promising consolidation strategy in selected patients. PEER REVIEWED ARTICLE **Peer reviewers:** Prof. Dr Stefan Balabanov, Department of Medical Oncology and Hematology, University Hospital Zurich, Zurich, Switzerland Prof. Dr Alicia Rovó, Department of Hematology and Central Hematology Laboratory, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland Received on January 19, 2026; accepted after peer review on February 19, 2026; published online on February 23, 2026.