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: UMLS:C0598934 (tumor growth)
58,965 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Iressa (ZD1839) is a p.o.-active, selective, epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) that blocks signal transduction pathways implicated in cancer cell proliferation, survival, and host-dependent processes promoting cancer growth. EGFR is up-regulated in primary malignant tumors of the central nervous system (CNS) and in many systemic tumors that metastasize to the CNS. The purpose of our study was to evaluate the efficacy and toxicity of p.o.-administered ZD1839 for the treatment of established intracerebral (i.c.) tumors expressing EGFR or the tumorigenic mutated variant EGFRvIII, which is constitutively phosphorylated. Oral administration of ZD1839 at 50 or 100 mg/kg/day for 3 weeks in athymic mice with established i.c. A431 human epidermoid carcinoma expressing EGFR increased median survival by 88% (P = 0.009) and 105% (P < 0.001), respectively. Additionally, there was no evidence of systemic or CNS toxicity. However, ZD1839 failed to inhibit either s.c. or i.c. in vivo tumor growth when tumorigenicity was conferred by EGFRvIII. Western blotting revealed that treatment with ZD1839 virtually ablated phosphorylation of EGFR Tyr-1173 in A431 tumors. However, treatment of NR6M tumors with ZD1839 only partially decreased phosphorylation of EGFRvIII Tyr-1173 while up-regulating overall expression, suggesting that EGFRvIII may not be susceptible to the same molecular mechanisms of tyrosine kinase inhibition as EGFR. In conclusion, ZD1839 is active in a brain tumor model expressing EGFR, but not EGFRvIII, as EGFR mutations may lead to relative therapeutic resistance. On the basis of these observations, we believe that clinical trials of ZD1839 against brain tumors expressing EGFR are warranted, but that special consideration should be given to tumors that coexpress EGFRvIII.
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PMID:Brain tumors in mice are susceptible to blockade of epidermal growth factor receptor (EGFR) with the oral, specific, EGFR-tyrosine kinase inhibitor ZD1839 (iressa). 1242 40

We have identified a novel class of 6-thiazolylquinazolines as potent and selective inhibitors of both ErbB-2 and EGFR tyrosine kinase activity, with IC(50) values in the nanomolar range. These compounds inhibited the growth of both EGFR (HN5) and ErbB-2 (BT474) over-expressing human tumor cell lines in vitro. Using xenograft models of the same cell lines, we found that the compounds given orally inhibited in vivo tumor growth significantly compared with control animals.
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PMID:Discovery and biological evaluation of potent dual ErbB-2/EGFR tyrosine kinase inhibitors: 6-thiazolylquinazolines. 1263 47

EGFRvIII is a tumor specific, ligand-independent, constitutively active variant of the epidermal growth factor receptor. Its expression has been detected in many human malignancies including breast cancer. No detectable level of EGFRvIII has, however, been observed in adult tissues, including normal breast tissues. These unique features of the EGFRvIII make it an excellent target for biologically based therapies. We have designed and generated a tumor specific ribozyme targeted to EGFRvIII. This specific EGFRvIII ribozyme is able to effectively cleave EGFRvIII mRNA under physiological conditions in a cell-free system, but does not cleave wild-type EGFR and other EGF-family receptors. While expressing this EGFRvIII-ribozyme in breast cancer cells, EGFRvIII-ribozyme is capable of downregulating endogenous EGFRvIII expression at the mRNA and protein levels. Inhibition of proliferation was observed in EGFRvIII-ribozyme transfectants. In addition, downregulation of EGFRvIII in breast cancer cells significantly inhibited tumor growth in athymic nude mice. Furthermore, this ribozyme has no effect on EGF-family receptor expression or the proliferation of breast cancer cells, which do not express EGFRvIII but express wild-type EGFR and other EGF-family receptors. These results suggest that we have generated a tumor-specific, biologically functional ribozyme and further demonstrate that EGFRvIII plays a significant role in breast cancer cell proliferation. The ultimate goal of this approach is to provide a potential treatment for breast cancer by specifically targeting this receptor.
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PMID:Suppression of EGFRvIII-mediated proliferation and tumorigenesis of breast cancer cells by ribozyme. 1264 Jun 78

Gefitinib (brand name: Iressa) is a drug approved for molecule-targeting therapy in lung carcinoma patients. There are still many unresolved problems concerning the safety and mechanism of action of this drug. Based on the expectation that this drug combined with immunotherapy would be highly effective, we recently conducted an experiment in tumor-bearing mice. In this experiment, however, the tumor was not significantly reduced in size by this combined therapy. However, since the tumor in this animal model was EGFR positive and because tumor growth tended to be suppressed in mice with higher immune activity, it seems likely that additional studies of this therapy will contribute to identifying the optimum drugs to be combined with gefitinib and the optimum method of dosing that will lead to satisfactory efficacy and safety of gefitinib combined with immunotherapy.
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PMID:[Significance of gefitinib combined with immunotherapy in tumor-bearing mice]. 1461 16

Fifteen% or fewer of patients with non-small cell lung cancer (NSCLC) survive 5 years. The current standard of care for patients with locally advanced or metastatic NSCLC is systemic chemotherapy with a two-drug combination regimen that includes a platinum agent. Although systemic chemotherapy reduces the rate of death attributable to lung cancer, disease progression is inevitable and dose-limiting toxicities restrict their use. New molecularly targeted therapies aim to inhibit specific pathways and key molecules implicated in tumor growth and progression while sparing normal cells. Several therapies, which target signal transduction pathways involved in angiogenesis, metastasis, and apoptosis, are in clinical development to treat lung cancer. Among these targeted therapies are the oral, small-molecule epidermal growth factor receptor-tyrosine kinase (EGFR-TK) inhibitors gefitinib and erlotinib. Both therapies have been validated preclinically as new treatment approaches for NSCLC and have shown single-agent activity against advanced, chemorefractory NSCLC in clinical trials. This article focuses on the biology of the EGFR-TK signal transduction pathway, its role in the proliferation of solid tumors, and the rationale for the clinical development of EGFR-TK inhibitors. We also review clinical trials with EGFR-TK inhibitors in NSCLC and future directions of investigation with these targeted agents.
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PMID:Targeting the epidermal growth factor receptor in non-small cell lung cancer. 1467 1

Erlotinib (Tarceva) is an orally available selective small-molecule inhibitor of HER1/EGFR tyrosine kinase with a 50% inhibitory concentration of 2 nM for purified tyrosine kinase. This agent has been shown to produce stasis or regression of tumor growth in human cancer xenograft models, including non-small-cell lung cancer models. Ongoing preclinical investigations indicate that inhibition of the MAPK and Atk signaling pathways downstream of HER1/EGFR may be required for optimal antitumor effects. Erlotinib exhibits inhibition of MAPK and Atk kinases at concentrations higher than those required for HER1/EGFR tyrosine kinase inhibition; such findings suggest that maximal inhibition of HER1/EGFR, requiring high erlotinib doses, is necessary for optimum antitumor activity. These considerations are supported by tumor models, including non-small-cell lung cancer models, showing dose-related antitumor effects up to high doses of erlotinib. Erlotinib exhibits additive antitumor effects when combined with chemotherapeutic agents (cisplatin, doxorubicin, paclitaxel, gemcitabine [Gemzar], and capecitabine [Xeloda]), radiation therapy, and other targeted agents (e.g., bevacizumab [Avastin]). Recent studies indicate that erlotinib inhibits the EGFRvIII mutant at concentrations higher than those required for inhibition of wild-type receptor. Ongoing investigation will help to determine optimal dosing and dose frequency of erlotinib in various cancers in the clinical setting.
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PMID:Erlotinib: preclinical investigations. 1468 18

Lung cancer is very frequent and associated with a high mortality. In the last 25 years therapeutic progress have been limited and do not allow a 5 year global survival rate exceeding to 13-14%. Tumor biology permits a better comprehension of cancerization mechanisms and offers hope of new treatments with targeted therapies which would be specific of cancer cells and so more efficient and less toxic. Epidermal growth factor (EGF) pathway and its receptor (EGFR) expressed by most lung cancer cells is the most successfully completed example. The bond of EGF with its receptor stimulates tyrosine kinase domain of EGFR and allows transduction of an activating signal. Inhibition of this signaling pathway stops tumor growth. Several agents are in development, from preclinical studies to phase III trials. It is a matter of humanized monoclonal antibodies, such as C225 (cetuximab), targeted against EGFR, or small molecules inhibiting tyrosine kinase activity of EGFR including ZD1839 (Iressa), OS1774 (Tarceva) or CI1033, and last antisense oligonucleotides. Antibodies and small molecules are well tolerated and are responsible for limited amount of side effects, mostly cutaneous toxicity and diarrhoea. Antitumor activity has been observed in monotherapy reaching up to 25% of clinical responses in the best series. EGFR inhibition seems to be also promising in combination with chemotherapy according to the synergy observed in preclinical studies and response rate up to 50% have been reported. But phase III studies have been disappointing and additional studies are warranted before consideration for a current daily practice, mostly that severe secondary effects were reported with pulmonary toxicities. In particular it remains to explain why clinical responses do not appear correlated with EGFR expression.
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PMID:[Therapeutic implications of epidermal growth factor receptor in lung cancer]. 1476 45

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

Human malignant tumors, such as non-small lung, breast, ovarian, head and neck, prostate, stomach and colorectal cancers express a number of growth factor receptors (e.g. EGFR or EGFR family members) that are regulated by tumor hypoxia and contribute to tumor growth and failure of cytotoxic therapy. Paclitaxel and docetaxel are indispensable substances in the treatment of these tumors. Despite the active clinical use of taxanes, little is known about their cytotoxic activity under hypoxia. The aim of the present work was to compare the cytotoxic effect of taxanes, paclitaxel and docetaxel on the EGFR-expressing carcinoma cell lines A431, MDA-MB-231 and NCI-H358 under normoxic and hypoxic conditions. The two taxanes caused different cell cycle distribution and varying aneuploid cell formation under hypoxia. EGFR-overexpressing carcinoma cells showed hypoxia to severely affect the cytotoxicity of paclitaxel, whereas docetaxel preserved its tumor cell-killing activity even at lowest concentrations (0.5 nM), as was observed for both taxanes under normoxia.
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PMID:Effects of paclitaxel and docetaxel on EGFR-expressing human carcinoma cells under normoxic versus hypoxic conditions in vitro. 1533 13

Heparin-binding EGF-like growth factor (HB-EGF) exists as a membrane-anchored form (proHB-EGF) and as its soluble cleaved product (sHB-EGF). The conversion (ectodomain shedding) of proHB-EGF to sHB-EGF is tightly regulated by specific metalloproteinases. Ectodomain shedding plays a central role in GPCR-mediated EGFR transactivation. Antagonizing metalloproteinases can inhibit EGFR transactivation and might be of therapeutic value, for example in cardiac hypertrophy, skin remodeling and tumor growth.
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PMID:Metalloproteinase-mediated shedding of heparin-binding EGF-like growth factor and its pathophysiological roles. 1554 65


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