Original Article

Annals of Hematology

, Volume 89, Issue 7, pp 663-669

Expression of pSTAT5 predicts FLT3 internal tandem duplications in acute myeloid leukemia

  • Ellen Christina ObermannAffiliated withInstitute of Pathology, University of Basel
  • , Caroline ArberAffiliated withHematology Unit, University of Basel
  • , Martine JotterandAffiliated withUnité cytogénétique du cancer, Centre Hospitalier Universitaire Vaudois
  • , Andre TichelliAffiliated withHematology Unit, University of Basel
  • , Petra HirschmannAffiliated withInstitute of Pathology, University of Basel
  • , Alexandar TzankovAffiliated withInstitute of Pathology, University of Basel Email author 

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Mutations of the Fms-like tyrosine kinase 3 (FLT3) can be detected in a significant number of acute myeloid leukemias (AML). Seventy-five cases of acute myeloid leukemia were evaluated for FLT3-internal tandem duplications (ITD) by polymerase chain reaction. Paraffin-embedded formalin-fixed trephine biopsies of these cases were evaluated for expression of phosphorylated signal transducer and activator of transcription 1 (pSTAT1), pSTAT3, and pSTAT5. Specific expression of pSTAT5 was proven in leukemic blasts in situ by double staining with a blast-specific marker. Expression of pSTAT5 in ≥1% of blasts was highly predictive of FLT3-ITD. Neither expression of pSTAT1 nor pSTAT3 were associated with FLT3 mutations. Altogether we conclude that pSTAT5 expression can precisely be assessed by immunohistochemistry in routinely processed bone marrow trephines, STAT5 is highly likely the preferred second messenger of FLT3-mediated signaling in AML, and expression of pSTAT5 is predictive of FLT3-ITD.


Acute myeloid leukemia FLT3 FLT3-ITD pSTAT5