Eosinophilic myeloid disorders: new classification and novel therapeutic strategies.
OBJECTIVE
The aim of this brief review is to evaluate recent developments in the classification and treatment of eosinophilic myeloid disorders in the context of reactive, lymphocyte-variant, and idiopathic eosinophilias.


RESULTS
The revised 2008 WHO classification recognizes both molecularly defined ('myeloid and lymphoid neoplasms with eosinophilia and abnormalities of PDGFRA, PDGFRB, or FGFR1') and undefined (chronic eosinophilic leukemia, not otherwise specified) eosinophilic myeloid disorders. An increasingly sophisticated understanding of the molecular underpinnings of eosinophilia has translated into rational use of biologically targeted therapies such as imatinib mesylate. Conventional cytotoxics and interferon-alpha still have an established role in treating these diseases. Although studied in idiopathic hypereosinophilic syndrome, the therapeutic niche of anti-interleukin-5 (mepolizumab) and anti-CD52 (alemtuzumab) antibody therapy in eosinophilic myeloid diseases has yet to be established.


CONCLUSIONS
Molecular/genetic analysis is now mandatory for the diagnosis, classification, and treatment of eosinophilic myeloid disorders. The finding of rearranged, constitutively activated PDGFRA/B identifies patients who are eminently treatable with tyrosine kinase inhibitors.
Gotlib
Jason
J
Stanford University School of Medicine, Stanford Cancer Center, Stanford, California, USA. jason.gotlib@stanford.edu
D014408:Biomarkers, Tumor / Q000235:genetics; D006801:Humans; D017681:Hypereosinophilic Syndrome / Q000145:classification / Q000188:drug therapy* / Q000235:genetics; D007951:Leukemia, Myeloid / Q000145:classification / Q000188:drug therapy*; D047428:Protein Kinase Inhibitors / Q000627:therapeutic use*; D051496:Receptor, Fibroblast Growth Factor, Type 1 / Q000235:genetics; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000235:genetics; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000235:genetics; D014944:World Health Organization
D014408:Biomarkers, Tumor; D047428:Protein Kinase Inhibitors; C496348:FGFR1 protein, human; D051496:Receptor, Fibroblast Growth Factor, Type 1; D020796:Receptor, Platelet-Derived Growth Factor alpha; D020797:Receptor, Platelet-Derived Growth Factor beta