A Case Report of BCR-ABL-JAK2-Positive Chronic Myeloid Leukemia with Complete Hematological and Major Molecular Response to Dasatinib

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm (MPN) that harbors the Philadelphia chromosomal translocation resulting in the uncontrolled production of mature granulocytes. Commonly, patients are diagnosed with CML during blood work for other reasons or enlarged spleen. The diagnosis is based on WHO criteria that require the demonstration of Philadelphia chromosome. Typically, JAK2 mutation is not found in BCR-ABL1-positive MPN (CML). Most patients with CML are JAK2 negative. It is rare for CML Philadelphia-positive patients to have a coexisting JAK2 mutation. Little is known regarding the effect of JAK2 mutation on the disease course of CML, the complications, and the response to treatment. We report the case of a 57-year-old man with no previous medical illness who presented with elevated white blood cell count on perioperative assessment for hernial repair; on further workup, he was diagnosed with Philadelphia-positive CML. He was found to have JAK2 mutation and was started on treatment with dasatinib and achieved hematological and cytogenetic remission with loss of the JAK2 mutation. Patients with JAK2-positive BCR-ABL-positive CML had a good hematological and cytogenetic response to dasatinib. In such rare coexistence of JAK and BCR-ABL, dasatinib is a good option due to multi-kinase activity.