Rare but authentic Philadelphia-positive acute myeloblastic leukemia: two case reports and a literature review of characteristics, treatment and outcome

Abstract

The Philadelphia chromosome (Ph+), corresponding to translocation t(9;22), is found in chronic myeloid leukemia (CML) and acute lymphoblastic leukemia. Several cases of Ph+ acute myeloid leukemia (AML) have been reported in the literature. A retrospective study of Ph+ AML between 2001 and 2012 was conducted through a review of the literature. Among 400 AML patients, two cases of Ph+ AML (0.5%) were identified and treated with conventional chemotherapy with or without tyrosine kinase inhibitors (TKIs), followed by allogeneic hematopoietic stem cell transplantation (allo-HSCT). One patient had a complex karyotype including 7 monosomy (-7) and p190 BCR-ABL fusion transcript. Both patients remain in complete molecular remission. To date, 21 Ph+ AML cases treated with TKIs have been described in the literature with a median overall survival of 18months. One-third of the patients had additional karyotypic abnormalities, and 14% had -7. Molecular analysis showed 59% p210 and 41% p190 fusion protein. Relapse rate was observed in 38% of patients with p190 compared to 10% in patients with p210. Allo-HSCT was performed in eight patients; two relapsed (25%). Cytogenetic (-7) and molecular features help to distinguish Ph+ AML from CML. Survival improved with TKIs, particularly in association with conventional chemotherapy and allo-HSCT. Further studies of Ph+ AML patients are needed to better define this entity, its prognostic value, and therapeutic strategy.

Keywords: Acute myeloid leukemia; Allogeneic stem cell transplantation; Philadelphia chromosome; Tyrosine kinase inhibitor.