Chronic myeloid leukemia (CML) is currently a disease in which patients can enjoy a near normal life-expectancy. However, since the majority of patients will need to remain on treatment indefinitely, physicians in care of CML patients need be familiar with the indications and toxicities of all approved tyrosine kinase inhibitors (TKI). In clinical practice, there are five TKI (imatinib, nilotinib, dasatinib, bosutinib, and ponatinib) that are available in different scenarios and have distinct safety profiles. Decisions regarding first line treatment must be based on CML risk, comorbidities, and patients expectations. Despite the excellent outcome, half of the patients will eventually fail (due to intolerance or resistance) to first line treatment, with many of them requiring a third or even further lines of therapy. When selecting for such patients, it is essential to distinguish between failure and intolerance to previous TKIs. In the present review, we will address all these issues from a practical point of view.

Currently, no effective treatment is available for the nonlymphoid blast crisis (BC) of chronic myeloid leukemia (CML) and because of this the prognosis for such patients remains invariably poor. In an attempt to determine the results provided by palliative treatment with oral 6-mercaptopurine (6-MP) in the above hematological condition, 30 such patients were analyzed for hospital stay, days of intravenous (i.v.) antibiotics, transfusion requirements, response rate, and survival. Thirty patients with nonlymphoid BC matched for their initial characteristics and treated with different i.v. regimens were used for comparison purposes. Patients managed with 6-MP spent less days in hospital (median: 9, range: 0-46 vs median: 42, range: 5-140; P<0.0001), needed antibiotics for less days (median: 0. range: 0-46 vs median: 20, range: 0-57; P<0.0001), and received less platelet transfusions (median: 0, range: 0-20 vs median: 6, range: 0-63; P=0.004) than those treated with i.v. chemotherapy. Although no complete or partial remission was achieved by patients receiving 6-MP vs six in the i.v. chemotherapy group, no significant difference was observed when the survival of both groups was compared (median: 4.7 months, range: 0.1-22.7 vs median: 3.8 months, range: 0.2-12, respectively). These results indicate that 6-MP therapy constitutes a good palliative treatment for patients with nonlymphoid BC of CML. However, new treatment strategies for this hematological condition are required.

Isochromosome 17q [i(17q)] is frequently observed in the blast crisis (BC) of chronic myelogenous leukemia (CML). It has been suggested that this chromosome abnormality is associated with special hematological characteristics of the BC, but the information on this subject is scarce. The clinical, hematological and cytogenetic features of patients with i(17q) were analyzed in a series of 121 patients with BC of Ph-positive CML. Twelve patients (10%) displayed an i(17q), representing the third commonest cytogenetic abnormality, after trisomy 8 and Ph chromosome duplication. In seven of the 12 patients the BC was preceded by an accelerated phase, and 10 had more than 10% blood basophils at BC diagnosis. The blast cells had a myeloid phenotype in the 12 patients. Five patients exhibited cytogenetic abnormalities in addition to i(17q), with trisomy 8 and duplication of the Ph chromosome being the alterations most frequently observed. Median survival of patients with i(17q) was 22 weeks, which was not significantly different from the survival of patients with myeloid BC in the overall series. These results are similar to the findings in 181 patients with i(17q) from 12 series of the literature, and confirm the special hematologic profile of BC of CML with this cytogenetic abnormality.