Atypical Phenotype and Treatment Response Pattern in a Patient with FIP1L1-PDGFRα Mutation.

Myeloproliferative disorders with eosinophilia may possess the FIP1L1-PDGFRα gene rearrangement. When this rearrangement is present, imatinib usually results in complete remission. In rare cases of imatinib resistance, there is poor evidence guiding second-line therapy. We present the case of a 71-year-old male who presented with abdominal discomfort, fevers, and leukocytosis with eosinophilia. The patient was diagnosed with a myeloproliferative neoplasm with eosinophilia and FIP1L1-PDGFRα rearrangement after a bone marrow evaluation revealed hypercellular marrow with eosinophilia and fluorescence in situ hybridization identified the FIP1L1-PDGFRα rearrangement. The patient was successfully treated with imatinib. Within months he relapsed and converted into acute myeloid leukemia. The patient was then treated with ponatinib which induced and maintained clinical and hematological remission for 2 months. That ponatinib briefly induced remission in our patient with acute myeloid leukemia arising from a myeloproliferative neoplasm with eosinophilia and FIP1L1-PDGFRα fusion may merit exploration of ponatinib as a potential second-line treatment option for this patient population. This is especially true given the lack of reliable therapies in instances of imatinib resistance.