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 tyrosine kinase (TK) inhibitor, imatinib, has revolutionized therapy of malignancies that are addicted to one of its target kinases, c-abl, c-kit and PDGF-R. This addiction is generally dependent on the acquisition of an activating kinase mutation, e.g., the bcr-abl fusion gene in chronic myeloid leukemia, or point mutations of KIT or PDGFRA in gastrointestinal stroma tumors (GIST). Other types of sarcomas are generally considered to be insensitive to imatinib. We have observed a striking and durable remission of an advanced angiosarcoma to imatinib that can only be explained by TK addiction. Unexpectedly, GIST-type KIT and PDGFRA mutations were absent in this case. This case illustrates the diagnostic challenges in identifying individual candidate patients for TK inhibitor therapy.
 ...
PMID:Dramatic and durable efficacy of imatinib in an advanced angiosarcoma without detectable KIT and PDGFRA mutations. 1918 35

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.
 ...
PMID:Optimizing treatment with Bcr-Abl tyrosine kinase inhibitors in Philadelphia chromosome-positive chronic myeloid leukemia: focus on dosing schedules. 1925 84

The therapeutic efficacy of imatinib mesylate is based on its specific inhibition of several tyrosine kinases (TKs) implicated in the disease pathogenesis. These enzymes include BCR/ABL in patients with chronic myeloid leukaemia, PDGF-R alpha and beta in patients with certain myeloproliferative disorders and dermatofibrosarcoma protuberans and c-KIT in patients with gastrointestinal tumors. Most patients tolerate the drug well and apparently no metabolic abnormalities are evidenced during treatment. However, different metabolic effects have been reported as a consequence of imatinib inhibition during treatment of patients with CML. The aim of this review is to report the changes caused by imatinib on glucose, lypidic and bone metabolism.
 ...
PMID:The metabolic consequences of imatinib mesylate: Changes on glucose, lypidic and bone metabolism. 1930 18

Platelet-derived growth factor (PDGF) receptors (PDGFR) and their ligands play critical roles in several human malignancies. Sunitinib is a clinically approved multitargeted tyrosine kinase inhibitor that inhibits vascular endothelial growth factor receptor, c-KIT, and PDGFR, and has shown clinical activity in various solid tumors. Activation of PDGFR signaling has been described in gastrointestinal stromal tumors (PDGFRA mutations) as well as in chronic myeloid leukemia (BCR-PDGFRA translocation), and sunitinib can yield clinical benefit in both settings. However, the discovery of PDGFR activating mutations or gene rearrangements in other tumor types could reveal additional patient populations who might benefit from treatment with anti-PDGFR therapies, such as sunitinib. Using a high-throughput cancer cell line screening platform, we found that only 2 of 637 tested human tumor-derived cell lines show significant sensitivity to single-agent sunitinib exposure. These two cell lines [a non-small-cell lung cancer (NSCLC) and a rhabdomyosarcoma] showed expression of highly phosphorylated PDGFRA. In the sunitinib-sensitive adenosquamous NSCLC cell line, PDGFRA expression was associated with focal PFGRA gene amplification, which was similarly detected in a small fraction of squamous cell NSCLC primary tumor specimens. Moreover, in this NSCLC cell line, focal amplification of the gene encoding the PDGFR ligand PDGFC was also detected, and silencing PDGFRA or PDGFC expression by RNA interference inhibited proliferation. A similar codependency on PDGFRA and PDGFC was observed in the sunitinib-sensitive rhabdomyosarcoma cell line. These findings suggest that, in addition to gastrointestinal stromal tumors, rare tumors that show PDGFC-mediated PDGFRA activation may also be clinically responsive to pharmacologic PDGFRA or PDGFC inhibition.
 ...
PMID:Ligand-dependent platelet-derived growth factor receptor (PDGFR)-alpha activation sensitizes rare lung cancer and sarcoma cells to PDGFR kinase inhibitors. 1936 96

According to the 2008 World Health Organization classification system for hematologic malignancies, the myeloproliferative neoplasms (MPN) include chronic myelogenous leukemia, polycythemia vera, essential thrombocythemia, primary myelofibrosis, mastocytosis, chronic eosinophilic leukemia-not otherwise specified, chronic neutrophilic leukemia, and "MPN, unclassifiable." All of these clinicopathologic entities are characterized by stem cell-derived clonal myeloproliferation, and their phenotypic diversity is ascribed to the occurrence of distinct oncogenic events. In the last 4 years, new JAK2 and MPL mutations have been added to previously described ABL and KIT mutations as molecular markers of disease in MPN. These discoveries have markedly simplified the approach to clinical diagnosis and have also provided molecular targets for the development of small-molecule drugs. In the current article, the authors provide a clinically oriented overview of MPNs in terms of their molecular pathogenesis, classification, diagnosis, and management.
 ...
PMID:Advances in understanding and management of myeloproliferative neoplasms. 1936 82

The development of imatinib resistance has become a significant therapeutic problem in which the etiology seems to be multifactorial and poorly understood. As of today, clinical criteria to predict the development of imatinib resistance in chronic myelogenous leukemia (CML), other than rebound of the myeloproliferation, are under development. However, there is evidence that the control of glucose-substrate flux is an important mechanism of the antiproliferative action of imatinib because imatinib-resistant gastrointestinal stromal KIT-positive tumors reveal highly elevated glucose uptake in radiologic images. We used nuclear magnetic resonance spectroscopy and gas chromatography mass spectrometry to assess (13)C glucose uptake and metabolism (glycolysis, TCA cycle, and nucleic acid ribose synthesis) during imatinib treatment in CML cell lines with different sensitivities to imatinib. Our results show that sensitive K562-s and LAMA84-s BCR-ABL-positive cells have decreased glucose uptake, decreased lactate production, and an improved oxidative TCA cycle following imatinib treatment. The resistant K562-r and LAMA84-r cells maintained a highly glycolytic metabolic phenotype with elevated glucose uptake and lactate production. In addition, oxidative synthesis of RNA ribose from (13)C-glucose via glucose-6-phosphate dehydrogenase was decreased, and RNA synthesis via the nonoxidative transketolase pathway was increased in imatinib-resistant cells. CML cells which exhibited a (oxidative/nonoxidative) flux ratio for nucleic acid ribose synthesis of >1 were sensitive to imatinib. The resistant K562-r and LAMA84-r exhibited a (oxidative/nonoxidative) flux ratio of <0.7. The changes in glucose uptake and metabolism were accompanied by intracellular translocation of GLUT-1 from the plasma membrane into the intracellular fraction in sensitive cells treated with imatinib, whereas GLUT-1 remained located at the plasma membrane in LAMA84-r and K562-r cells. The total protein load of GLUT-1 was unchanged among treated sensitive and resistant cell lines. In summary, elevated glucose uptake and nonoxidative glycolytic metabolic phenotype can be used as sensitive markers for early detection of imatinib resistance in BCR-ABL-positive cells.
 ...
PMID:Abnormalities in glucose uptake and metabolism in imatinib-resistant human BCR-ABL-positive cells. 1940 45

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.
 ...
PMID:Class effects of tyrosine kinase inhibitors in the treatment of chronic myeloid leukemia. 1947

Imatinib (Gleevec, Novartis), an inhibitor of BCR-ABL, platelet-derived growth factor, and KIT receptor tyrosine kinases, is widely used in the treatment of chronic myelogenous leukemia and gastrointestinal stromal tumors. We describe a case of activation of chronic hepatitis B infection associated with imatinib therapy.
 ...
PMID:Reactivation of chronic hepatitis B infection related to imatinib mesylate therapy. 1966 26

Gastrointestinal stromal tumors (GIST) are characterized by activating mutations of KIT or platelet-derived growth factor receptor A (PDGFRA), and treatment with the tyrosine kinase inhibitor imatinib yields responses in the majority of patients. However, most patients develop secondary resistance, which is associated with a dismal prognosis. Histone deacetylase inhibitors (HDACI) have been shown to enhance imatinib activity in imatinib-resistant chronic myelogenous leukemia. Against this background, we explored whether HDACI might provide an alternative therapeutic strategy to KIT/PDGFRA kinase inhibitors in GIST. Inhibition of cell proliferation by HDACI was seen in KIT-positive but not in KIT-negative GIST cell lines, suggesting that HDACI activity is mainly conferred by targeting oncogenic KIT. KIT activity, expression, and activation of downstream pathways were strongly inhibited by several HDACI (SAHA, LBH589, VPA, trichostatin A, and NaButyrate). SAHA and LBH589 induced apoptosis in KIT-positive GIST, and strong synergism with imatinib was observed at low concentrations of SAHA and LBH589. Mechanistically, treatment with HDACI reduced KIT mRNA transcript levels and led to strong acetylation of HSP90, interfering with its activity as KIT chaperone. These results provide preclinical evidence for a disease-specific effect of HDACI in KIT-positive GIST, which could translate into therapeutic activity.
 ...
PMID:Inhibitors of deacetylases suppress oncogenic KIT signaling, acetylate HSP90, and induce apoptosis in gastrointestinal stromal tumors. 1970 76

The 2008 WHO classification system for hematological malignancies is comprehensive and includes histology and genetic information. Myeloid neoplasms are now classified into five categories: acute myeloid leukemia, myelodysplastic syndromes (MDS), myeloproliferative neoplasms (MPN), MDS/MPN, and myeloid and/or lymphoid malignancies associated with eosinophilia and PDGFR or FGFR1 rearrangements. MPN are subclassified into eight separate entities: chronic myelogenous leukemia, polycythemia vera, essential thrombocythemia, primary myelofibrosis, systemic mastocytosis, chronic eosinophilic leukemia not otherwise specified, chronic neutrophilic leukemia, and unclassifiable MPN. The diagnosis of chronic myelogenous leukemia requires the presence of BCR-ABL1, while its absence is required for all other MPN. Additional MPN-associated molecular markers include mutations of JAK2, MPL, TET2 and KIT. JAK2 V617F is found in most patients with polycythemia vera, essential thrombocythemia, or primary myelofibrosis and is, therefore, useful as a clonal marker in those settings. The diagnostic utility of MPL and TET2 mutations is limited by low mutational frequency. In systemic mastocytosis, presence of KIT D816V is expected but not essential for diagnosis. Chronic eosinophilic leukemia not otherwise specified should be distinguished from both PDGFR-rearranged or FGFR1-rearranged neoplasms and hypereosinophilic syndrome. We discuss histologic, cytogenetic and molecular changes in MPN and illustrate their integration into practical diagnostic algorithms.
 ...
PMID:Myeloproliferative neoplasms: contemporary diagnosis using histology and genetics. 1980 46


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>