Imatinib mesylate was the first tyrosine kinase inhibitor (TKI) approved for the management of chronic myeloid leukemia. Imatinib produces acceptable responses in approximately 60% of patients, with approximately 20% discontinuing therapy because of intolerance and approximately 20% developing drug resistance. The advent of newer TKIs, such as nilotinib, dasatinib, bosutinib, and ponatinib, has provided multiple options for patients. These agents are more potent, have unique adverse effect profiles, and are more likely to achieve relevant milestones, such as early molecular responses (3–6 months) and optimal molecular responses (12 months). The acquisition of BCR-ABL kinase domain mutations is also reportedly lower with these drugs. Thus far, none of the randomized phase III clinical trials have shown a clinically significant survival difference between frontline imatinib versus newer TKIs. Cost and safety issues with the newer TKIs, such as vascular disease with nilotinib and ponatinib and pulmonary hypertension with dasatinib, have dampened the enthusiasm of using these drugs as frontline options. While the utility of new TKIs in the setting of imatinib failure or intolerance is clear, their use as frontline agents should factor in the age of the patient, additional comorbidities, risk stratification (Sokal score), and cost. Combination therapies and newer agents with potential to eradicate quiescent chronic myeloid leukemia stem cells offers future hope.
From the Division of Hematology, Department of Internal Medicine, Mayo Clinic, Rochester, MN.
Current publication is supported in part by grants from The Henry J. Predolin Foundation for Research in Leukemia, Mayo Clinic, Rochester, MN. This publication was supported by CTSA Grant Number KL2 TR000136 from the National Center for Advancing Translational Science (NCATS). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIH.
The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article.
The contents of this study are solely the responsibility of the authors and do not necessarily represent the official view of National Institutes of Health.
Reprints: Mrinal M. Patnaik, MD, Division of Hematology, Department of Internal Medicine, Mayo Clinic, 200 First St, SW Rochester, MN 55905. E-mail: Patnaik.firstname.lastname@example.org.