T790M突变和cMet扩增

老马 发表于 2013-7-11 00:30

                               
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Establishment and characterization of an erlotinib-resistant clone derived from the EGFRL858R NSCLC  ...

厄洛替尼的耐药是因为EGFR野生细胞的扩增造成的，那这种情况下最佳的治疗是化疗吗？

感谢老马哥带来最前沿的消息，我家还不能确定是哪一种突变，是不是只能一个个试药了

是不是发现吃易缓慢耐药后可以穿插一两个月的4002？对可能发生的T790m突变压制一下。

c-MET as a potential therapeutic target and biomarker in cancer
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3225018/

Potential resistant factors to c-MET inhibitors
As with other TKI inhibitors, sensitive cells/tumors treated with c-MET inhibitors develop resistance [Cepero et al. 2010b; Sierra et al. 2010]. Since no clinical specimens are still available, only preclinical in vitro systems have been able to predict the possible mechanisms of resistance that patients will develop when exposed to anti-MET treatments. So far, three mechanisms of resistance to c-MET inhibitors have been described. First, cells treated with c-MET TKI at high fixed doses develop a dependency on EGFRs [Corso et al. 2010; McDermott et al. 2010]. Both reports conclude that cells harboring high MET copy number will undergo an oncogenic switch that will create an ERBB tyrosine kinase dependency, similar to the oncogenic switch from EGFR to c-MET in NSCLC cells. The second known mechanism of resistance reported by Cepero et al. [2010a] is that when c-MET-dependent NSCLC and gastric cell lines are exposed to increasing doses of c-MET inhibitors amplify wild-type MET and KRAS, it enables cells to overcome the inhibitory threshold of the compound and still sustain high MAPK and PI3K/AKT activity. The third reported mechanism of resistance is the acquisition of a point mutation in the activation loop of c-MET (Y1230H) [Qi et al. 2011]. This mutation had previously been described as a somatic mutation in hereditary and sporadic renal carcinomas [Giordano et al. 2000]; here it has been shown to overcome the inhibitory effect of any c-MET kinase inhibitor.
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Cytotoxic Activity of Tivantinib (ARQ 197) Is Not Due Solely to c-MET Inhibition
http://cancerres.aacrjournals.org/content/73/10/3087.figures-only
Katayama R, Aoyama A, Yamori T, Qi J, Oh-hara T, Song Y, Engelman JA, Fujita N.
Source
Massachusetts General Hospital Cancer Center, Boston, MA, USA.
Abstract
The receptor tyrosine kinase c-MET is the high-affinity receptor for the hepatocyte growth factor (HGF). The HGF/c-MET axis is often dysregulated in tumors. c-MET activation can be caused by MET gene amplification, activating mutations, and auto- or paracrine mechanisms. Thus, c-MET inhibitors are under development as anticancer drugs. Tivantinib (ARQ 197) was reported as a small-molecule c-MET inhibitor and early clinical studies suggest antitumor activity. To assess whether the antitumor activity of tivantinib was due to inhibition of c-MET, we compared the activity of tivantinib with other c-MET inhibitors in both c-MET-addicted and nonaddicted cancer cells. As expected, other c-MET inhibitors, crizotinib and PHA-665752, suppressed the growth of c-MET-addicted cancers, but not the growth of cancers that are not addicted to c-MET. In contrast, tivantinib inhibited cell viability with similar potency in both c-MET-addicted and nonaddicted cells. These results suggest that tivantinib exhibits its antitumor activity in a manner independent of c-MET status. Tivantinib treatment induced a G(2)-M cell-cycle arrest in EBC1 cells similarly to vincristine treatment, whereas PHA-665752 or crizotinib treatment markedly induced G(0)-G(1) cell-cycle arrest. To identify the additional molecular target of tivantinib, we conducted COMPARE analysis, an in silico screening of a database of drug sensitivities across 39 cancer cell lines (JFCR39), and identified microtubule as a target of tivantinib. Tivantinib-treated cells showed typical microtubule disruption similar to vincristine and inhibited microtubule assembly in vitro. These results suggest that tivantinib inhibits microtubule polymerization in addition to inhibiting c-MET.

老马 发表于 2013-8-7 02:15

                               
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c-MET as a potential therapeutic target and biomarker in cancer
http://www.ncbi.nlm.nih.gov/pmc/art ...

和其它TKI抑制剂一样，经过c-MET抑制剂治疗的敏感细胞/肿瘤也会发展出耐药。

因缺乏临床切片，只有临床前体外系统能够预测病人接受抗MET治疗后可能发展出的耐药机制。

目前有三种c-MET抑制剂的耐药机制被描述过。

第一种，经过固定剂量的c-MET TKI治疗的细胞发展出对EGFR的依赖。两例报导总结出有高MET复制数的细胞将会形成一个致癌开关，该开关将会造成ERBB TKI，类似非小里的从EGFR到c-MET的致癌开关。

第二种，当c-MET依赖非小细胞和胃癌细胞暴露在增量的c-MET抑制剂放大MET和KRAS野生型时，该疗法使得细胞克服化合物的抑制阈值并仍然保持高MAPK 和 PI3K/AKT 活性。

第三种，c-MET活性循环中的获得性点突变。该突变此前曾被描述为遗传和零星胃癌中的体细胞突变，在此这个机制被证明能够克服任何c-MET TKI的抑制作用。

Tivantinib (ARQ 197) 联合特罗凯的临床结果显示：
（1）腺癌类型相对鳞癌类型，cMet扩增的概率更大，更受益于cMet抑制剂联合特罗凯；
（2）cMet低表达的腺癌病人在Tivantinib (ARQ 197) 联合特罗凯组没有比特罗凯单药更差；
以前关于这个实验说cMet低表达的病人用cmet药会缩短生存期，最新的亚组分析显示不是这回事儿.

老马 发表于 2013-8-7 02:35

                               
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Cytotoxic Activity of Tivantinib (ARQ 197) Is Not Due Solely to c-MET Inhibition
http://cancerres.a ...

The receptor tyrosine kinase c-MET is the high-affinity receptor for the hepatocyte growth factor (HGF).
受体酪氨酸激酶c-MET是与肝细胞生长因子（HGF）高亲和性的受体。

The HGF/c-MET axis is often dysregulated in tumors. c-MET activation can be caused by MET gene amplification, activating mutations, and auto- or paracrine mechanisms.
HGF/c-MET信号通路通常在肿瘤中失调。MET基因的扩增、激活突变和自分泌或者旁分泌机制都能导致c-MET的激活。

Thus, c-MET inhibitors are under development as anticancer drugs.
因此，作为抗肿瘤药物，一系列c-MET抑制剂正在开发中。

Tivantinib (ARQ 197) was reported as a small-molecule c-MET inhibitor and early clinical studies suggest antitumor activity.
Tivantinib (ARQ 197)是一种小分子c-MET抑制剂并在早期临床研究中表现出抗肿瘤活性。

To assess whether the antitumor activity of tivantinib was due to inhibition of c-MET, we compared the activity of tivantinib with other c-MET inhibitors in both c-MET-addicted and nonaddicted cancer cells.
为了验证tivantinib的抗肿瘤活性是否来自于其对c-MET的抑制作用，我们比较了tivantinib和其他c-MET抑制剂在对c-MET依赖的肿瘤细胞和非依赖型肿瘤细胞中的活性。

As expected, other c-MET inhibitors, crizotinib and PHA-665752, suppressed the growth of c-MET-addicted cancers, but not the growth of cancers that are not addicted to c-MET.
如预期所示，其他c-MET抑制剂如crizotinib和PHA-665752，都只能抑制c-MET依赖的肿瘤的生长，无法作用于非c-MET依赖型肿瘤。

In contrast, tivantinib inhibited cell viability with similar potency in both c-MET-addicted and nonaddicted cells.
作为对比，tivantinib对c-MET依赖型和非依赖型细胞的生长都表现出了相似的抑制效力。

These results suggest that tivantinib exhibits its antitumor activity in a manner independent of c-MET status.
这些结果表明tivantinib展现出独立于c-MET状态的抗肿瘤活性。

Tivantinib treatment induced a G(2)-M cell-cycle arrest in EBC1 cells similarly to vincristine treatment, whereas PHA-665752 or crizotinib treatment markedly induced G(0)-G(1) cell-cycle arrest.
类似于长春新碱，Tivantinib在EBC1细胞中诱导G(2)-M细胞周期的停滞，相比之下，PHA-665752或crizotinib着重于诱导G(0)-G(1)细胞周期的停滞。

To identify the additional molecular target of tivantinib, we conducted COMPARE analysis, an in silico screening of a database of drug sensitivities across 39 cancer cell lines (JFCR39), and identified microtubule as a target of tivantinib.
为了识别tivantinib作用的其他靶点，我们在39种肿瘤细胞中采用了COMPARE分析，这是一种基于药物敏感性数据库的虚拟筛选，我们识别出了作为tivantinib靶点之一的微管。

Tivantinib-treated cells showed typical microtubule disruption similar to vincristine and inhibited microtubule assembly in vitro. These results suggest that tivantinib inhibits microtubule polymerization in addition to inhibiting c-MET.
经过tivantinib处理后的细胞显示出类似于长春新碱诱导的典型的微管解聚，在体外实验中也表现出对微管组装的抑制。这些结果都表明除了c-MET，tivantinib还能抑制细胞微管的聚合

非常有价值的东西，顶一个！老马辛苦了！

Abstract 1788: Mechanism of resistance to c-Met tyrosine kinase inhibitors in human melanoma
http://cancerres.aacrjournals.or ... etingAbstracts/1788
The over-expression of c-Met and activation by its ligand, hepatocyte growth factor (HGF), are known to cause significant tumor development and metastasis in human melanoma. Hence, c-Met is an attractive target for molecular therapeutic inhibition. To assess c-Met inhibition, we studied the effects of c-Met tyrosine kinase inhibitors (TKIs) in RU melanoma cells and found that JNJ38877605 and SU11274 (c-Met TKIs) inhibited cell growth in RU cells with an IC50 of 0.5 and 1µM, respectively. We then tested the therapeutic effects of JNJ38877605 in vivo. Five million RU melanoma cells were injected subcutaneously into the hind flanks of nude mice. Tumors were allowed to develop for a week after which daily oral treatments of 20 mg/kg JNJ38877605 or vehicle were given. We found that JNJ38877605 decreased the size of RU tumor xenografts in nude mice by 6 fold compared to mice treated with a vehicle control. Unfortunately, while c-Met inhibitors have been successful in clinical trials, acquired resistance to c-Met TKIs (ARQ197) and antibodies (MetMab) has been observed in cancer patients, resulting in tumor recurrence or lack of tumor CR. To determine the mechanism of c-Met TKI resistance, two melanoma cell line models, MU and RU, were exposed to increasing concentrations of SU11274. They proliferated in 7-10 fold higher concentrations of SU11274, and were cross resistant to 12 fold higher concentrations of JNJ38877605. After generating resistant cells, we measured HGF production and the expression levels of p-c-Met (Y1003) and p-c-Met (Y1234/1235) by immunoblotting to compare parental and resistant cells. We found that MU resistant cells exhibited upregulation of p-c-Met (Y1003) (6 fold) and p-c-met (Y1234/1235) (4 fold) compared to parental cells after treatment with HGF. Additionally, p-c-Met (Y1234/1235) was stable for only 30 min in parental cells compared to 60 min in resistant cells, where it was upregulated by 3-fold. This might be due to defects in c-Met ubiquitination resulting in its being recycled back or stabilized onto the membrane. Interestingly, we found that RU parental cells secreted 2 fold more HGF than the resistant cells. This indicates that resistant RU cells may not be as dependent on HGF induced activation in comparison to parental cells. In MU and RU resistant cells, we also found upregulation of p-mTOR (2 and 8 fold, respectively). Upregulation of phospho-pS6kinase (2 fold) and p-4E-BP1 (4 fold), downstream targets of p-mTOR, were also seen in MU cells. MU resistant cells also expressed increases in active β-catenin (protein downstream of Wnt signaling pathway) by 5 fold under no HGF stimulation and 2 fold after 60 min of HGF treatment. Our data indicates that the oral c-Met TKI, JNJ38877605, could be a promising therapeutic option for treating HGF producing melanoma tumors, but its effects could be further enhanced by the addition of mTOR and/or Wnt inhibitors to counteract acquired c-Met TKI resistance.