Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.10.1 (ERK)
95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Our objective was the preclinical assessment of the pharmacokinetics, monotherapy and combined antitumor activity of the epidermal growth factor receptor (HER1/EGFR) tyrosine kinase inhibitor erlotinib in athymic nude mice bearing non-small cell lung cancer (NSCLC) xenograft models. Immunohistochemistry determined the HER1/EGFR status of the NSCLC tumor models. Pharmacokinetic studies assessed plasma drug concentrations of erlotinib in tumor- and non-tumor-bearing athymic nude mice. These were followed by maximum tolerated dose (MTD) studies for erlotinib and each chemotherapy. Erlotinib was then assessed alone and in combination with these chemotherapies in the NSCLC xenograft models. Complete necropsies were performed on most of the animals in each study to further assess antitumor or toxic effects. Erlotinib monotherapy dose-dependently inhibited tumor growth in the H460a tumor model, correlating with circulating levels of drug. There was antitumor activity at the MTD with each agent tested in both the H460a and A549 tumor models (erlotinib 100 mg/kg: 71 and 93% tumor growth inhibition; gemcitabine 120 mg/kg: 93 and 75% tumor growth inhibition; cisplatin 6 mg/kg: 81 and 88% tumor growth inhibition). When each compound was given at a fraction of the MTD, tumor growth inhibition was suboptimal. Combinations of gemcitabine or cisplatin with erlotinib were assessed at 25% of the MTD to determine efficacy. In both NSCLC models, doses of gemcitabine (30 mg/kg) or cisplatin (1.5 mg/kg) with erlotinib (25 mg/kg) at 25% of the MTD were well tolerated. For the slow growing A549 tumor, there was significant tumor growth inhibition in the gemcitabine/erlotinib and cisplatin/erlotinib combinations (above 100 and 98%, respectively), with partial regressions. For the faster growing H460a tumor, there was significant but less remarkable tumor growth inhibition in these same combinations (86 and 53% respectively). These results show that in NSCLC xenograft tumors with similar levels of EGFR expression, the antitumor activity of erlotinib is robust both as monotherapy and in combination with chemotherapies.
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PMID:Antitumor activity of erlotinib (OSI-774, Tarceva) alone or in combination in human non-small cell lung cancer tumor xenograft models. 1516 26

Molecular inhibition of epidermal growth factor receptor (EGFR/HER1) signaling is under active investigation as a promising cancer treatment strategy. We examined the potency of EGFR inhibition achieved by combining anti-EGFR monoclonal antibody and tyrosine kinase inhibitor, which target extracellular and intracellular domains of the receptor, respectively. We specifically studied the combination of cetuximab (Erbitux, C225; ImClone Systems, New York, NY) with either gefitinib (Iressa, ZD1839; AstraZeneca, Macclesfield, UK) or erlotinib (Tarceva, OSI-774; Genentech, South San Francisco, CA) across a variety of human cancer cells. The combination of cetuximab plus gefitinib or erlotinib enhanced growth inhibition over that observed with either agent alone. As measured by immunostaining, inhibition of EGFR phosphorylation with the combination of cetuximab plus gefitinib or erlotinib was augmented over that obtained with single-agent therapy in head and neck (H&N) cancer cell lines. Phosphorylation inhibition of downstream effector molecules [mitogen-activated protein kinase (MAPK) and AKT] also was enhanced in tumor cells treated with the combination of cetuximab plus gefitinib or erlotinib. Flow cytometry and immunoblot analysis demonstrated that treatment of H&N tumor cells with cetuximab in combination with either gefitinib or erlotinib amplified the induction of apoptosis. Following establishment of cetuximab-resistant cell lines, we observed that gefitinib or erlotinib retained the capacity to inhibit growth of lung and H&N tumor cells that were highly resistant to cetuximab. Treatment with gefitinib or erlotinib, but not cetuximab, also could further inhibit the activation of downstream effectors of EGFR signaling in cetuximab-resistant cells, including MAPK and AKT. These data suggest that tyrosine kinase inhibitors may further modulate intracellular signaling that is not fully blocked by extracellular anti-EGFR antibody treatment. Finally, animal studies confirmed that single EGFR inhibitor treatment resulted in partial and transient tumor regression in human lung cancer xenografts. In contrast, more profound tumor regression and regrowth delay were observed in mice treated with the combination of cetuximab and gefitinib or erlotinib. Immunohistochemical staining, which demonstrated significant reduction of the proliferative marker proliferating cell nuclear antigen in mice treated with dual EGFR inhibitors, further supported this in vivo observation. Together, these data suggest that combined treatment with distinct EGFR inhibitory agents can augment the potency of EGFR signaling inhibition. This approach suggests potential new strategies to maximize effective target inhibition, which may improve the therapeutic ratio for anti-EGFR-targeted therapies in developing clinical trials.
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PMID:Dual-agent molecular targeting of the epidermal growth factor receptor (EGFR): combining anti-EGFR antibody with tyrosine kinase inhibitor. 1528 42

HER gene family (HER1-HER4) encodes structurally similar transmembrane proteins (EGFR, HER2, ErB-3, and ErB-4) with tyrosine kinase activity. Dimerised on binding with a number of ligands, including epidermal growth factor (EGF) and transforming growth factor alpha (TGFalpha), these proteins stimulate epithelial cell proliferation. HER2 and EGFR overexpression is detected in the cells of many tumours, mainly in breast, lung and oral cancer and may be connected with HER2 gene amplification or point mutations as well as with the presence of overactive polymorphic forms of HER1 gene. The first medication of a proved efficacy in breast cancer treatment was trastuzumab (Herceptin)--monoclonal antibody against HER2 protein. Trastuzumab was effective only in the case of patients with high HER2 expression evaluated by immunohistochemical methods and with gene amplification ascertained by fluorescence in situ hybridisation assays. In non-small-cell lung cancer (NSCLC), HER2 overexpression was detected only in a few cases. Therefore, trastuzumab treatment seems to be problematic in NSCLC patients. A small molecule quinazoline (erlotinib, Tarceva) is a promising therapeutic agent selectively blocking EGFR. Phase III Tarceva clinical trail in NSCLC patients showed that their survival is prolonged and that the medication acts together with other chemotherapeutic agents like cisplatin and gemcitabine.
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PMID:Anti-HER therapeutic agents in the treatment of non-small-cell lung cancer. 1531 69

GW572016 (Lapatinib) is a tyrosine kinase inhibitor in clinical development for cancer that is a potent dual inhibitor of epidermal growth factor receptor (EGFR, ErbB-1) and ErbB-2. We determined the crystal structure of EGFR bound to GW572016. The compound is bound to an inactive-like conformation of EGFR that is very different from the active-like structure bound by the selective EGFR inhibitor OSI-774 (Tarceva) described previously. Surprisingly, we found that GW572016 has a very slow off-rate from the purified intracellular domains of EGFR and ErbB-2 compared with OSI-774 and another EGFR selective inhibitor, ZD-1839 (Iressa). Treatment of tumor cells with these inhibitors results in down-regulation of receptor tyrosine phosphorylation. We evaluated the duration of the drug effect after washing away free compound and found that the rate of recovery of receptor phosphorylation in the tumor cells reflected the inhibitor off-rate from the purified intracellular domain. The slow off-rate of GW572016 correlates with a prolonged down-regulation of receptor tyrosine phosphorylation in tumor cells. The differences in the off-rates of these drugs and the ability of GW572016 to inhibit ErbB-2 can be explained by the enzyme-inhibitor structures.
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PMID:A unique structure for epidermal growth factor receptor bound to GW572016 (Lapatinib): relationships among protein conformation, inhibitor off-rate, and receptor activity in tumor cells. 1537 80

Targeted biological treatments are aimed at correcting one or several abnormalities inherent to cancer cells by specifically affecting one or several identified abnormal cell mechanisms. Many signalisation pathways involve membrane receptors of the tyrosine kinase receptor family, notably the HER receptors (with, first-line, EGFR or epidermal growth factor receptor) and the VEGF receptors. These receptors can be blocked either by a monoclonal antibody directed against the ligand (i.e., bevacizumab or anti-VEGF Avastin) or against the extra-cellular segment of the receptor (i.e., cetuximab or anti-EGFR Erbitux) or by tyrosine kinase inhibitors of the intracellular segment of the receptor (i.e., gefitinib or Iressa and erlotinib or Tarceva). The preliminary studies with these new treatments in pulmonary oncology are presented.
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PMID:[The place of targeted treatments: receptor tyrosine kinase inhibitors]. 1553 57

Although chemotherapy remains the standard of care for lung cancer, new less toxic drugs are urgently needed. Targeted agents represent a new era in cancer therapy, and non-small-cell lung cancer (NSCLC) is at the forefront of many development programs. An exciting target is the human epidermal growth factor receptor (EGFR, ie, HER1), and agents targeting this receptor, including gefitinib, cetuximab, and erlotinib (OSI-774; Tarceva), are being investigated. These agents have antitumor activity and are less toxic than most therapies. Based on phase II data, gefitinib received US approval for third-line treatment of patients with locally advanced or metastatic NSCLC. Cetuximab is licensed in the United States for patients with metastatic colorectal carcinoma. However, erlotinib, recently approved in the United States for second- and third-line treatment of patients with locally advanced or metastatic NSCLC, is the only agent of this class to improve survival as monotherapy in patients with advanced, refractory NSCLC, as shown in a phase III placebo-controlled trial. Phase III trials of erlotinib and gefitinib combined with chemotherapy were disappointing, which could be the result of drug scheduling, chemotherapy combinations, or other factors. Patient characteristics may also affect outcome, and research is ongoing to identify predictive markers of response to enable patient selection and improve outcome. Recently identified mutations within the HER1/EGFR tyrosine kinase (TK) domain may provide insight into why some patients respond rapidly to HER1/EGFR tyrosine kinase inhibitors. Surrogate markers of efficacy are also being investigated, including rash, which could be used to monitor and optimize antitumor activity. Therefore, although more work is required, data indicate that HER1/EGFR inhibitors will play an important role in treating patients with NSCLC.
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PMID:Overview of the current status of human epidermal growth factor receptor inhibitors in lung cancer. 1563 59

An increasing number of patients with advanced non-small cell lung cancer (NSCLC) progressing after front-line chemotherapy are still in good performance status and willing to receive further treatment. Several drugs have been tested in this setting of treatment, but the only agent registered world-wide for second-line chemotherapy of advanced NSCLC is docetaxel. This drug, at dose of 75 mg/m2 every three weeks, has been the standard of care as second-line chemotherapy since 2000, based on two trials that reported improved survival times and quality of life when comparing with best supportive care (TAX 317) and with ifosfamide or vinorelbine (TAX 320). Docetaxel, given at this dose and schedule, resulted in significant haematological toxicity, with many patients at risk for neutropenic fever. Pemetrexed is a novel multitargeted antifolate agent with single-agent activity in first- and second-line treatment of NSCLC. In a phase III study in 571 patients pemetrexed, comparing with docetaxel in second-line chemotherapy, demonstrated clinically equivalent therapeutic outcomes, but a more favourable haematological toxicity profile, with fewer episodes of neutropenia, neutropenic fever, and infections and less use of granulocyte colony-stimulating factor support. Others several agents have been evaluated for the second-line treatment of patients with non-small cell lung cancer, but no comparative phase III studies with docetaxel has been carried out. The epidermal growth factor receptor-tyrosine kinase inhibitors gefitinib (ZD1839, Iressa) and erlotinib (OSI 774, Tarceva) have been evaluated in the second- and third-line setting. Both drugs have demonstrated interesting response rates and toxicity profile and, in particular, erlotinib evidenced a survival advantage of 2 months respect placebo in recent phase III trial. Future developments are likely to value poli-chemotherapy or combination chemotherapy with EGFR tyrosine kinase inhibitors in second-line treatment of advanced NSCLC.
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PMID:Second-line chemotherapy in the treatment of advanced non-small cell lung cancer (NSCLC). 1568 23

Renal cell carcinoma accounts for approximately 3% of adult malignancies and 90%-95% of neoplasms arising from the kidney. It is characterized by a lack of early warning signs, diverse clinical manifestations, resistance to radiation and chemotherapy, and infrequent but reproducible responses to immunotherapy with agents such as interferon alpha (IFNa) and interleukin 2 (IL-2). International studies have shown objective response rates of < 15% in patients with advanced and metastatic disease, with 5-year disease-specific survival ranging between 0-20%. Considering these poor outcomes, renal cancers' very vascular nature and overexpression of receptors for vascular endothelial growth factor (VEGF), various biologic and angio-suppressive therapies are being evaluated in clinical trials. Promising results in terms of overall response rate and median time to progression have been reported especially as second-line therapy following cytokine failure, a setting where no effective systemic therapy has been recognized (SU011248, Bay 43-9006, Bevacizumab and Erlotinib). While confirmatory studies are ongoing, other novel treatments in first line trials (CCI-779, Infliximab, PTK-787, and Thalidomide) have drawn international attention. This review, analyzing basic translational research principles, will summarize the available data on the use of these new therapeutic approaches in RCC.
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PMID:New treatments for metastatic kidney cancer. 1578 Jan 70

Erlotinib (Tarceva) is an orally available HER1 (epidermal growth factor receptor, EGFR) tyrosine kinase inhibitor advancing through clinical trials for the treatment of a range of human malignancies. In this study, we examine the capacity of erlotinib to modulate radiation response and investigate specific mechanisms underlying these interactions in human tumor cell lines and xenografts. The impact of erlotinib on cell cycle kinetics was analyzed using flow cytometry, and the impact on apoptosis was evaluated via fluorescein-labeled pan-caspase inhibition and poly(ADP-ribose) polymerase cleavage. Radiation-induced EGFR autophosphorylation and Rad51 expression were examined by Western blot analysis. Radiation survival was analyzed using a clonogenic assay and assessment of in vivo tumor growth was done using a mouse xenograft model system. Microarray studies were carried out using 20 K human cDNA microarray and select genes were validated using quantitative reverse transcription-PCR (RT-PCR). Independently, erlotinib and radiation induce accumulation of tumor cells in G(1) and G(2)-M phase, respectively, with a reduction of cells in S phase. When combined with radiation, erlotinib promotes a further reduction in S-phase fraction. Erlotinib enhances the induction of apoptosis, inhibits EGFR autophosphorylation and Rad51 expression following radiation exposure, and promotes an increase in radiosensitivity. Tumor xenograft studies confirm that systemic administration of erlotinib results in profound tumor growth inhibition when combined with radiation. cDNA microarray analysis assessing genes differentially regulated by erlotinib following radiation exposure identifies a diverse set of genes deriving from several functional classes. Validation is confirmed for several specific genes that may influence radiosensitization by erlotinib including Egr-1, CXCL1, and IL-1beta. These results identify the capacity of erlotinib to enhance radiation response at several levels, including cell cycle arrest, apoptosis induction, accelerated cellular repopulation, and DNA damage repair. Preliminary microarray data suggests additional mechanisms underlying the complex interaction between EGFR signaling and radiation response. These data suggest that the erlotinib/radiation combination represents a strategy worthy of further examination in clinical trials.
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PMID:Mechanisms of enhanced radiation response following epidermal growth factor receptor signaling inhibition by erlotinib (Tarceva). 1583 66

Specific and reversible EGFR tyrosine kinase inhibitors (TKI) such as gefitinib and erlotinib are clinically active in advanced or metastatic NSCLC and both are approved in various countries for the treatment of patients that failed prior chemotherapy. Erlotinib has also prolonged survival in pancreatic cancer patients when added to gemcitabine and regulatory approval in this disease is being sought. Additional promising activity has been seen in other tumor types, such as ovarian cancer or head and neck malignancies, and phase III trials in these malignancies are ongoing or planned. Despite these successes, these agents have exhibited anecdotal or modest activity when used as single agents in unselected patients with various other tumor types. We have learned that the clinical development of these agents is far from simple and we need to better understand biological and clinical criteria for patient selection and how to best use the different available agents. The recent discovery of EGFR mutations and the potential identification of other markers that might predict patient response could help to optimize the use of these agents in the future. Irreversible EGFR inhibitors, dual EGF/HER2 and pan-ErbB receptor inhibitors may have greater antitumor activity although the tolerance of these compounds compared to specific EGFR TKIs needs further characterization. HER2 specific TKIs are also in development. Lapatinib, a dual EGFR/HER2 TK inhibitors, is particularly promising in breast cancer. Newer agents, such as BMS-599626, have recently entered into the clinic. In addition to the use of these agents as single agents, many clinical studies are addressing the role of combining them with hormonal agents, biological agents or chemotherapy.
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PMID:Small molecules with EGFR-TK inhibitor activity. 1585 87


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