1. ¹Institute for Drug Development, Cancer Therapy and Research Center at the University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
2. ²Department of Hematology, University College Hospital, Galway, Ireland

Correspondence: Dr FJ Giles, CTRC at The UT Health Science Center at San Antonio, Institute for Drug Development, 7979 Wurzbach Road, San Antonio, TX 78229, USA. E-mail: frankgiles@aol.com

Received 19 March 2009; Revised 6 April 2009; Accepted 17 April 2009; Published online 28 May 2009.

Abstract

Tyrosine kinase inhibitors have revolutionized the treatment of chronic myeloid leukemia (CML), offering patients several targeted therapeutic options that provide the possibility of sustained remissions and prolonged survival. With the availability of imatinib, nilotinib and dasatinib, physicians must weigh the efficacy and safety profile of each agent when choosing the best therapeutic option for individual patients. Each agent targets tyrosine kinases within the cell uniquely to cause the desired antiproliferative effect. In addition to inhibiting the BCR-ABL kinase, imatinib and nilotinib target the same array of other tyrosine kinases, including c-KIT and platelet-derived growth factor receptor (PDGFR), albeit with differing potencies. While targeting BCR-ABL with the highest potency among approved agents in CML, dasatinib also targets a broad array of off-target kinases, including SRC family members, PDGFR and EPHB4. The differences in kinase inhibition profiles among these agents in vitro probably account for the differing clinical safety profiles of these agents. This paper reviews the various kinases inhibited by imatinib, nilotinib and dasatinib, and describes the potential impact of kinase inhibition on the efficacy and safety of each agent.