- Chronic myelogenous leukemia (CML) results from the clonal expansion of immature myeloid cells with the t (9,22) (Ph) translocation, that encodes the constitutively active tyrosine kinase oncogene, bcr/abl. Patients with chronic phase CML are currently being treated with either hemopoetic stem cell transplantation (HSCT), or with the recently approved tyrosine kinase inhibitor, imatinib. Previous data, using interferon in patients with CML, has shown that patients who do not achieve a major cytogenetic response (defined as >35% Ph+) have a shortened survival. These patients are often considered for HSCT. However, due to constraints of age, suitable donor, and patient choice, only a minority of patients will undergo this potentially curative procedure.