Hematopoietic cell transplantation for chronic myeloid leukemia and myelofibrosis

Myeloproliferative disorders (MPD) are clonal stem cell diseases, which typically include Philadelphia (Ph) chromosome/BCR-ABL - positive chronic myeloid leukemia (CML), polycythemia vera, idiopathic myelofibrosis, and essential thrombocytosis. Recently, the World Health Organization proposed that chronic myelomonocytic leukemia (CMML) and atypical CML (CML without evidence of Ph chromosome or BCR-ABL translocation) should also be considered as MPD. 1 Many of these disorders have been shown to arise from chromosomal abnormalities leading to mutations that result in proteins with abnormal tyrosine kinase activity. Ph-positive CML has been the prototype of these disorders, and treatment with specific inhibitors has dramatically altered the natural history of the disease. 2,3 The identification of JAK2 mutations as an important molecular event in the development of other MPD could similarly revolutionize treatment of JAK2 + MPD. 4 Nevertheless, many patients with CML and other MPD will fail to respond to tyrosine kinase inhibitors. For these patients allogeneic hematopoietic stem cell transplantation (HSCT) remains the most effective curative therapy. In this chapter we review the results of HSCT in CML and other MPD, and their current and future role in the treatment of these disorders in the era of tyrosine kinase inhibitors.