Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023473 (chronic myeloid leukemia)
 18,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The dual c-abl/Src kinase inhibitor, dasatinib, utilized to treat chronic myeloid leukaemia (CML) when used at clinically attainable sublethal concentrations, synergistically sensitized primary chronic lymphocytic leukaemia (CLL) lymphocytes to chlorambucil and fludarabine. In contrast, dasatinib alone demonstrated toxicity to CLL lymphocytes at concentrations that are generally not clinically attainable. Dasatinib resistance and poorer dasatinib-mediated sensitization to chlorambucil and fludarabine was associated with higher expression of c-abl protein levels. In contrast, chlorambucil and fludarabine resistance correlated with basal p53 protein levels. Moreover, Western blot analysis after in vitro treatment of primary CLL lymphocytes with dasatinib, chlorambucil and/or fludarabine, showed that dasatinib: (i) inhibited c-abl function (e.g. downregulation of c-abl protein levels and decreased the phosphorylation of a c-abl downstream target, Dok2), (ii) decreased chlorambucil/fludarabine induced accumulation of p53 protein levels, (iii) altered the response to chlorambucil/fludarabine induced DNA-damage as evidenced by an increase in chlorambucil/fludarabine-induced H2AX phosphorylation, and (iv) accentuated the c-abl downregulation induced by chlorambucil/fludarabine. Our results suggest that dasatinib in combination with chlorambucil or fludarabine may improve the therapy of CLL.
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PMID:Dasatinib sensitizes primary chronic lymphocytic leukaemia lymphocytes to chlorambucil and fludarabine in vitro. 1906 42

Chronic myeloid leukemia (CML) is characterized by the presence of the Philadelphia (Ph) chromosome, which results from a reciprocal translocation between the long arms of the chromosomes 9 and 22 t(9;22)(q34;q11). This translocation creates two new genes, BCR-ABL on the 22q- (Ph chromosome) and the reciprocal ABL-BCR on 9q-. The BCR-ABL gene encodes for a 210-kD protein with deregulated tyrosine kinase (TK) activity, which is crucial for malignant transformation in CML. The recognition of the BCR-ABL gene and corresponding protein led to the synthesis of small-molecule drugs, designed to interfere with BCR-ABL tyrosine kinase activation by competitive binding at the ATP-binding site. The first tyrosine kinase inhibitor (TKI), introduced into clinical practice in 1998, was imatinib mesylate. Imatinib became the first choice drug in chronic phase CML, because of its high efficacy, low toxicity and ability to maintain durable hematological and cytogenetic responses. However, approximately 20-25% of patients initially treated with imatinib will need alternative therapy, due to drug resistance, which is often caused by the appearance of clones expressing mutant forms of BCR-ABL. Second-generation TKIs have provided new therapeutic option for the patients resistant to imatinib. Dasatinib is the first, second-generation TKI, approved in the US and European Union for the treatment of CML patients with imatinib resistance or intolerance. This drug is a dual SRC-ABL kinase inhibitor, active in most clinically relevant BCR-ABL mutations, except highly resistant T315I. Other second-generation TKIs include nilotinib, bosutinib and INNO 406. Apart from TKIs, the promising group of molecules is inhibitors of Aurora family of serine-threonine kinases. One of these molecules, MK0457, has entered clinical trials, and initial reports indicate that this compound could be active in disease associated with T315I mutation. Thus, wide spectrum of new agents, with different mode of action, is currently in clinical development for CML. It is likely that combination therapy will be the best therapeutic strategy in the future.
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PMID:Targeted drugs in chronic myeloid leukemia. 1907 51

Tyrosine kinases (TKs) are attractive targets for cancer therapy, as quite often their abnormal signaling has been linked with tumor development and growth. Constitutive activated TKs stimulate multiple signaling pathways responsible for DNA repair, apoptosis, and cell proliferation. During the last few years, thorough analysis of the mechanism underlying tyrosine kinase's activity led to novel cancer therapy using TKs blockers. These drugs are remarkably effective in the treatment of various human tumors including head and neck, gastric, prostate and breast cancer and leukemias. The most successful example of kinase blockers is Imatinib (Imatinib mesylate, Gleevec, STI571), the inhibitor of Bcr/Abl oncoprotein, which has become a first-line therapy for chronic myelogenous leukemia. The introduction of STI571 for the treatment of leukemia in clinical oncology has had a dramatic impact on how this disease is currently managed. Others kinase inhibitors used recently in cancer therapy include Dasatinib (BMS-354825) specific for ABL non-receptor cytoplasmic kinase, Gefitinib (Iressa), Erlotinib (OSI-774, Tarceva) and Sunitinib (SU 11248, Sutent) specific for VEGF receptor kinase, AMN107 (Nilotinib) and INNO-406 (NS-187) specific for c-KIT kinase. The following TK blockers for treatment of various human tumors are in clinical development: Lapatinib (Lapatinib ditosylate, Tykerb, GW-572016), Canertinib (CI-1033), Zactima (ZD6474), Vatalanib (PTK787/ZK 222584), Sorafenib (Bay 43-9006, Nexavar), and Leflunomide (SU101, Arava). Herein, we discuss the chemistry, biological activity and clinical potential of new drugs with tyrosine kinase blockers for cancer treatment.
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PMID:Tyrosine kinase blockers: new hope for successful cancer therapy. 1914 83

Dasatinib is a highly potent Bcr-Abl inhibitor that is approved for the treatment of imatinib-resistant or -intolerant chronic myeloid leukemia (CML) and Philadelphia chromosome-positive acute lymphoblastic leukemia. Across a series of phase 2 and 3 trials, dasatinib was associated with durable treatment responses in all phases of the disease and was well tolerated. For this article, the authors reviewed available information on specific side effects associated with the use of dasatinib. On the basis of more than 2 years' experience of dasatinib treatment during clinical trials, they provide practical recommendations for side-effect management.
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PMID:Dasatinib treatment for Philadelphia chromosome-positive leukemias: practical considerations. 1919 46

Chronic myeloid leukemia (CML) is a cancer of the hematopoietic system and has been treated with the drug Imatinib relatively successfully. Drug resistance, acquired by mutations, is an obstacle to success. Two additional drugs are now considered and could be combined with Imatinib to prevent resistance, Dasatinib and Nilotinib. While most mutations conferring resistance to one drug do not confer resistance to the other drugs, there is one mutation (T315I) that induces resistance against all three drugs. Using computational methods, the combination of two drugs is found to increase the probability of treatment success despite this cross-resistance. Combining more than two drugs, however, does not provide further advantages. We also explore possible combination therapies using drugs currently under development. We conclude that among the targeted drugs currently available for the treatment of CML, only the two most effective ones should be used in combination for the prevention of drug resistance.
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PMID:Combination of two but not three current targeted drugs can improve therapy of chronic myeloid leukemia. 1920 94

Resistance to imatinib in patients with chronic myelogenous leukemia (CML) or Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) has emerged as a significant clinical issue. Dasatinib is a tyrosine kinase inhibitor that has 325-fold greater in vitro activity against native BCR-ABL (breakpoint cluster region-Abelson leukemia virus) compared with imatinib and can overcome primary (intrinsic) and secondary (acquired) imatinib resistance. Here, we review the clinical profile of dasatinib in imatinib-resistant and -intolerant patients and share clinical approaches for managing adverse events (AEs) to ensure maximum patient benefit. References were obtained through literature searches on PubMed as well as from the Proceedings of Annual Meetings of the American Society of Clinical Oncology, the American Society of Hematology, and European Hematology Association. Phase II and III studies of dasatinib in patients with imatinib-resistant or -intolerant CML in any phase or Ph+ ALL were selected for discussion. Dasatinib is currently indicated for the treatment of patients with imatinib-resistant or -intolerant CML or Ph+ ALL. AEs associated with dasatinib are typically mild to moderate, and are usually resolved with temporary treatment interruption and/or dose adjustments. A Phase III dose optimization study showed that in patients with chronic phase (CP) CML, 100 mg once-daily dasatinib improves the safety profile, particularly pleural effusion and thrombocytopenia, while maintaining efficacy compared with the previously recommended dose of 70 mg twice-daily. Dasatinib has a manageable safety profile. For patients with CP CML, a new recommended starting dose of 100 mg once daily has recently been approved. The recommended dose for patients with advanced CML or Ph+ ALL remains 70 mg twice daily.
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PMID:New dosing schedules of dasatinib for CML and adverse event management. 1923 16

Chronic myeloid leukemia (CML) is characterized by the presence of the Philadelphia chromosome (Ph), a genetic aberration that codes for bcrabl, which plays a key role in disease pathophysiology. The first oral inhibitor of Brc-Abl was imatinib, which also targets KIT and platelet-derived growth factor receptor kinase and has demonstrated improved outcomes when compared with interferon, the previous standard of care. Imatinib resistance and intolerance have been an issue for patients, and as a result, new therapeutic approaches have been evaluated. Dose-escalated imatinib (800 mg daily) has shown some limited activity in patients with imatinib-resistant CML, but the development of second-generation tyrosine kinase inhibitors has broadened the treatment options. Dasatinib is also an oral kinase inhibitor, but it has increased potency for Brc-Abl compared with imatinib. Dasatinib has demonstrated activity in all phases of CML and Ph+ acute lymphocytic leukemia and is approved for the treatment of adults in this setting. Recent phase III data have demonstrated that, in patients with chronic-phase CML, dasatinib 100 mg once daily is equally effective, with improved tolerability, compared with the previously approved 70-mg twice-daily dose. Nilotinib, which has been recently approved, has increased potency for Brc-Abl compared with imatinib and has demonstrated activity in patients with imatinib-resistant and -intolerant chronic- and accelerated-phase CML. As experience with these agents continues to mature, we might optimize the treatment efficacy and safety profiles by altering dose regimens.
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PMID:Optimizing treatment with Bcr-Abl tyrosine kinase inhibitors in Philadelphia chromosome-positive chronic myeloid leukemia: focus on dosing schedules. 1925 84

A phase 1/2 study was conducted to assess the safety and efficacy of dasatinib in Japanese patients with chronic myelogenous leukemia (CML) or Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph(+) ALL) resistant or intolerant to imatinib. In phase 1, 18 patients with chronic phase (CP) CML were treated with dasatinib 50, 70, or 90 mg twice daily to evaluate safety. Dasatinib <or= 90 mg twice daily was well tolerated. In phase 2, dasatinib 70 mg was given twice daily to CP-CML patients for 24 weeks and to CML patients in accelerated phase (AP)/blast crisis (BC) or Ph(+) ALL for 12 weeks. In the CP-CML group (n = 30) complete hematologic response was 90% and major cytogenetic response (MCyR) 53%. In the AP/BC-CML group (n = 11) major hematologic response (MaHR) was 64% and MCyR 27%, whereas in the Ph(+) ALL group (n = 13) MaHR was 38% and MCyR 54%. Dasatinib was well tolerated and most of the nonhematologic toxicities were mild or moderate. Dasatinib therapy resulted in high rates of hematologic and cytogenetic response, suggesting that dasatinib is promising as a new treatment for Japanese CML and Ph(+) ALL patients resistant or intolerant to imatinib.
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PMID:Phase 1/2 clinical study of dasatinib in Japanese patients with chronic myeloid leukemia or Philadelphia chromosome-positive acute lymphoblastic leukemia. 1926 90

Dasatinib, a tyrosine kinase inhibitor of BCR-ABL, was originally approved for the second-line treatment of any-phase chronic myelogenous leukemia (CML) or Philadelphia chromosome-positive acute lymphoblastic leukemia at a dosage of 70 mg twice daily. In chronic-phase (CP) CML resistant to first-line imatinib, this regimen is more efficacious than high-dose imatinib. A Phase III study of CP CML has now shown that dasatinib 100 mg once daily is therapeutically noninferior to 70 mg twice daily and has an improved safety profile. Patients receiving dasatinib 100 mg once daily suffered significantly fewer thrombocytopenia (grade 3-4) and pleural effusion (all grades) events than those receiving dasatinib 70 mg twice daily. Fewer patients receiving dasatinib 100 mg once daily also required dose interruption/reduction or discontinuation. The recommended regimen for dasatinib in patients with CP disease and who are resistant or intolerant to primary therapy with imatinib is now 100 mg once daily.
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PMID:New approved dasatinib regimen available for clinical use. 1927 7

Dasatinib was approved in 2006 for the treatment of imatinib-resistant chronic myelogenous leukemia and functions primarily through the inhibition of BCR-ABL and Src kinase. Dasatinib is extensively metabolized in humans by CYP3A4. In this study, we report that the bioactivation of dasatinib by CYP3A4 proceeds through a reactive intermediate that leads to CYP3A4 inactivation with K(I) = 6.3 microM and k(inact) = 0.034 min(-1). The major mechanism of inactivation proceeds through hydroxylation at the para-position of the 2-chloro-6-methylphenyl ring followed by further oxidation, forming a reactive quinone-imine, similar to the reactive intermediates formed by acetaminophen and diclofenac. Formation of a reactive imine-methide was also detected but appears to be a minor pathway. When glutathione was added to human liver microsomal incubations, dasatinib-glutathione adducts were detected. Numerous dasatinib analogs were synthesized in an effort to understand what modifications would block the formation of reactive intermediates during dasatinib metabolism. It is interesting to note that blocking the site of hydroxylation with a methyl group was not effective because a reactive imine-methide was formed, nor was blocking the site with fluorine because the fluorine was removed through an oxidative defluorination mechanism and the reactive quinone-imine was still formed. Numerous analogs are presented that did effectively block the formation of glutathione adducts and prevent the inactivation of CYP3A4.
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PMID:Characterization of dasatinib and its structural analogs as CYP3A4 mechanism-based inactivators and the proposed bioactivation pathways. 1928 95


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