In vivo antiproliferative effect of NS-187, a dual Bcr-Abl/Lyn tyrosine kinase inhibitor, on leukemic cells harbouring Abl kinase domain mutations
ABSTRACT Advanced-phase chronic myeloid leukemia patients treated with imatinib often relapse due to point mutations in the Abl kinase domain. We herein examine the in vitro and in vivo effects of a Bcr-Abl/Lyn dual tyrosine kinase inhibitor, NS-187, on seven mutated Bcr-Abl proteins. NS-187 inhibited both Tyr393-phosphorylated and Tyr393-unphosphorylated Abl, resulting in significant in vitro growth inhibition of cells expressing six of seven mutated Bcr-Abl kinases, though not T315I. Furthermore, NS-187 prolonged the survival of mice injected with leukemic cells expressing all mutated Bcr-Abl tested except T315I, and its efficacy correlated well with its in vitro effects.
SourceAvailable from: Moorthy S S Palanki[Show abstract] [Hide abstract]
ABSTRACT: Chronic myelogenous leukemia (CML) is a hematological stem cell disorder caused by increased and unregulated growth of myeloid cells in the bone marrow, and the accumulation of excessive white blood cells. Abelson tyrosine kinase (ABL) is a non-receptor tyrosine kinase involved in cell growth and proliferation and is usually under tight control. However, 95% of CML patients have the ABL gene from chromosome 9 fused with the breakpoint cluster (BCR) gene from chromosome 22, resulting in a short chromosome known as the Philadelphia chromosome. This Philadelphia chromosome is responsible for the production of BCR-ABL, a constitutively active tyrosine kinase that causes uncontrolled cellular proliferation. An ABL inhibitor, imatinib, was approved by the FDA for the treatment of CML, and is currently used as first line therapy. However, a high percentage of clinical relapse has been observed due to long term treatment with imatinib. A majority of these relapsed patients have several point mutations at and around the ATP binding pocket of the ABL kinase domain in BCR-ABL. In order to address the resistance of mutated BCR-ABL to imatinib, 2nd generation inhibitors such as dasatinib, and nilotinib were developed. These compounds were approved for the treatment of CML patients who are resistant to imatinib. All of the BCR-ABL mutants are inhibited by the 2nd generation inhibitors with the exception of the T315I mutant. Several 3rd generation inhibitors such as AP24534, VX-680 (MK-0457), PHA- 739358, PPY-A, XL-228, SGX-70393, FTY720 and TG101113 are being developed to target the T315I mutation. The early results from these compounds are encouraging and it is anticipated that physicians will have additional drugs at their disposal for the treatment of patients with the mutated BCR-ABL-T315I. The success of these inhibitors has greater implication not only in CML, but also in other diseases driven by kinases where the mutated gatekeeper residue plays a major role.Current Topics in Medicinal Chemistry 06/2008; 8(10):905-921. DOI:10.2174/156802608784911635 · 3.45 Impact Factor
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ABSTRACT: Chronic myelogenous leukemia (CML) is a disorder of hematopoietic stem cells that results from the Philadelphia chromosome (Ph) created through translocation of human chromosomes 9 and 22. The resulting Bcr-Abl fusion protein has constitutively high tyrosine kinase activity that causes transformation of hematopoietic stem cells. Imatinib mesylate (IM) was developed as a specific Bcr-Abl kinase inhibitor and is efficacious in treating Ph-chromosome-positive (Ph+) leukemias such as CML and Ph+ acute lymphoblastic leukemia (ALL). Within a few years of its introduction to the clinic, IM has dramatically altered the first-line therapy for CML. Although most newly diagnosed CML patients in the chronic phase (CP) achieved durable responses when treated with IM, resistance to IM has become a major problem in patients with advanced-stage disease. The most important mechanism of IM resistance are point mutations within the Abl kinase domain; therefore, there is an urgent need for novel agents that can inhibit mutated Bcr-Abl. In this review, we describe novel Bcr-Abl tyrosine kinase inhibitors, the so-called “Super Gleevec” inhibitors. Drug Dev Res 69:398–406, 2008. © 2008 Wiley-Liss, Inc.Drug Development Research 11/2008; 69(7):398 - 406. DOI:10.1002/ddr.20271 · 0.73 Impact Factor
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ABSTRACT: The advances in the understanding of the pathogenesis of multiple myeloma and the mechanism of drug resistance have led to the development of novel targeted therapies that are able to overcome resistance and show additive or synergistic effects with old chemotherapeutic agents. Thalidomide, its immunomodulatory derivative lenalidomide, and the proteasome inhibitor bortezomib, in combination with oral melphalan in the elderly and with intravenous melphalan in younger patients, are changing the traditional treatment paradigm of multiple myeloma. High-dose melphalan followed by autologous stem cell transplantation in the younger patients and oral melphalan-prednisone-thalidomide in the elderly are the standard of care for newly diagnosed multiple myeloma. In younger patients, combinations incorporating thalidomide or lenalidomide or bortezomib significantly increase the pre-transplant response rate before high-dose melphalan and autologous transplantation, and may further improve the response rate and survival achieved after transplant. Prospective randomized studies incorporating new agents and stratifying patients based on cytogenetic abnormalities, are needed to define the therapeutic algorithm in high-risk disease.Revista Brasileira de Hematologia e Hemoterapia 06/2008; 30:10-17. DOI:10.1590/S1516-84842008000800005