非受体酪氨酸激酶靶点在胃肠间质瘤治疗中的研究现状与进展

胃肠间质瘤（gastrointestinal stromal tumor,GIST）是最常见的间叶细胞来源的胃肠肿瘤。75%～80%和10%的GIST分别存在编码受体酪氨酸激酶的KIT或PDGFRA激活突变,还有约10%的GIST不存在KIT和PDGFRA突变,称之为野生型GIST。GIST的治疗主要是以KIT及PDGFRA为靶点的受体酪氨酸激酶抑制剂（tyrosine kinase inhibitor,TKI）靶向治疗。然而,耐药问题一直是TKI治疗的难点和热点。野生型GIST对TKI治疗不敏感。近些年来,越来越多的研究开始关注非酪氨酸激酶靶点在GIST治疗中的潜在价值。本文对GIST分子分型及靶向治疗进行综述,着重探讨非酪氨酸激酶靶点在GIST治疗中的研究现状与进展。     

胃肠道间质瘤KIT及PDGFRA基因突变的检测及分析

  目的  检测胃肠道间质瘤(gastrointestinal stromal tumors, GISTs)KIT及PDGFRA基因的突变位点及类型, 探讨其在GIST发病机制中的作用。  方法  收集西京医院病理科2006年10月至2010年10月胃肠道间质瘤病例38例, 男性20例(52.6%), 女性18例(47.4%), 从福尔马林固定石蜡包埋(formalin-fixed paraffin-embedded, FFPE)组织中提取基因组DNA。通过PCR扩增目的片段后测序, 检测38例样本的KIT和PDGFRA基因突变类型。  结果  在38例样本中共检测出KIT基因突变34例, 其中32例发生在外显子1 1, 突变形式有点突变、插入突变与缺失突变; 2例发生在外显子9, 均为重复性突变。同时还检出PDGFRA基因突变1例, 其余3例样本为野生型。  结论  大多数GISTs中存在KIT基因的突变, PDGFRA基因突变可见于部分缺乏KIT突变的GIST中。      

胃的胃肠间质瘤患者基因突变状态及预后分析

目的：分析胃的胃肠间质瘤（gastrointestinal stromal tumor,GIST）患者基因突变状态,探究不同基因突变类型对患者预后的影响。方法：回顾性分析华中科技大学同济医学院附属协和医院2012年1月—2021年6月术后行基因检测的胃GIST患者的临床病理资料。采用Kaplan-Meier法绘制生存曲线并计算存活率。采用COX比例风险模型进行单因素和多因素预后分析。结果：共纳入286例胃GIST患者,其中男性152例、女性134例;中位年龄为57岁（范围：21～85岁）。KIT基因第11、9、13、17号外显子突变比例分别为78.0%(223/286)、2.4%(7/286)、1.4%(4/286)、1.0%(3/286),血小板源性生长因子受体α(platelet-derived growth factor receptor alpha,PDGFRA)基因第18、12号外显子突变比例分别为10.1%(29/286)和0.7%(2/286),野生型胃GIST比例为6.3%(18/286)。KIT第11号外显子突变患者中缺失、置换、插入、重复及混合突变的比例分别为40....     

TKI类药物在胃肠间质瘤临床应用中耐药机制的最新研究进展

胃肠间质瘤（gastrointestinal stromal tumor,GIST）是胃肠道最常见的间叶源性肿瘤.绝大多数GIST的发病机制是受c-KIT(KIT proto-oncogene receptor tyrosine kinase)或血小板衍生生长因子受体α(platelet-derived growth factor receptor alpha,PDGFRA)基因的功能增益性突变驱动。原先GIST的临床治疗方案仅为手术切除,而以伊马替尼（imatinib）为代表的小分子酪氨酸激酶抑制剂（tyrosine kinase inhibtor,TKI）的问世则标志着GIST治疗进入靶向治疗的时代。TKI在GIST中取得了显著的临床疗效,目前已有多个TKI药物被批准用于临床治疗,极大地提高了GIST患者的生存期,但是紧随而来的耐药问题是一个亟需解决的难点。目前已明确GIST对TKI耐药的主要原因是c-KIT或PDGFRA不同外显子的继发突变。然而,即使是带有相同外显子突变的GIST患者,其对TKI的反应仍存在较大差异,暗示着可能存在与c-KIT和PDGFRA同时作用的其它机制。得...     

胃肠道间质瘤中c-kit和PDGFRA基因的突变及其意义

背景与目的:胃肠道间质瘤(GIST)是最常见的胃肠道间叶源性肿瘤,GIST中c-kit和PDGFRA基因突变及突变位点与甲磺酸伊马替尼(格列卫)治疗疗效有关,而突变与生物学行为的关系一直存有争议.本研究探讨GIST中c-kit和PDGFRA基因的突变情况及意义.方法:用PCR扩增和直接测序方法检测50例GIST中c-kit外显子9、11、13、17及PDGFRA基因外显子12、18的突变.结果:50例GIST中仅检测出c-kit外显子11突变,突变率为54%(27/50),均为杂合性突变.其中缺失性突变16例(59%)、点突变10例(37%),伴有点突变的缺失性突变1例.突变位点几乎均集中在5'端"热点"区(96%).CD117阴性的2例GIST中1例检测到c-kit外显子11突变.外显子11突变在不同组织学类型之间比较,差异有显著性(P＜0.05),而在不同原发部位及不同侵袭危险性之间比较,差异均无显著性(P＞0.05).结论:c-kit突变是GIST的普遍现象,突变位点有集中趋势,以梭形细胞型突变最常见.突变检测不能作为生物学行为判断参考指标.     

胃肠道间质瘤靶向治疗新进展

胃肠道间质瘤(GIST)是最常见的间叶组织源性肿瘤,分子生物学研究已揭示了其发病机制与KIT和PDGFRA基因突变有关。目前,GIST步入了手术及靶向治疗联合的时代,选择性酪氨酸激酶抑制剂伊马替尼等药物已应用于GIST的靶向治疗,干扰肿瘤发展的特定分子环节以延缓肿瘤的进展,并且取得较为理想的疗效,GIST已逐渐成为肿瘤分子靶向治疗的典型。     

非编码RNA在胃肠间质瘤中的研究进展

胃肠间质瘤(gastrointestinal stromal tumor,GIST)是消化道最常见的间叶源性肿瘤,发病原因主要是由于原癌基因受体酪氨酸激酶或血小板衍生生长因子受体基因活化突变。分子靶向治疗药物甲磺酸伊马替尼是抑制KIT、血小板衍生生长因子受体α多肽(platelet-derived growth factor receptor alpha,PDGFRA)基因酪氨酸激酶活性的药物,其能有效治疗进展期GIST。但是,越来越多的研究发现,甲磺酸伊马替尼在治疗GIST过程中存在原发性耐药和继发性耐药。随着近年来对非编码RNA的生理功能和作用机制的深入研究,使人们逐步认识到非编码RNA对基因表达的广泛调控作用,其在肿瘤发生、发展、侵袭、转移和耐药等过程中扮演着重要角色。研究非编码RNA有可能为探讨GIST发病及耐药机制提供新的思路和方向。     

GIST中imatinib耐药机制研究进展

在功能获得性突变所致的KIT或PDGFRA受体酪氨酸激酶异常活化与胃肠间质瘤（GIST）的发病关系阐明后,酪氨酸激酶抑制剂甲璜酸伊马替尼（imatinib）在进展期GIST中显现出很高的有效性,使GIST的治疗发生了革命性的改变。然而,GIST中对imatinib的早期或晚期耐药已经成为日益严重的临床问题。因此,对耐药的分子机制的进一步了解就成为当前研究的焦点,本文综述了目前对imatinib耐药的分子机制的认识,这些认识可能引导新的治疗策略的产生。     

胃肠间质瘤的分子学研究进展

胃肠间质瘤(gastrointestinal stromal tumor,GIST)是最常见的消化道间质肿瘤.研究发现在绝大部分GIST中存在原癌基因KIT的获得性功能突变,KIT具有酪氨酸激酶受体活性,应用伊马替尼阻断KIT受体活性是治疗GIST的方法之一,这些研究结果改变了GIST的治疗方式和预后前景.GIST的分子学特征在疾病诊断、靶向药物剂量选择以及伊马替尼耐药中均起着重要作用.本文就GIST在分子学方面的研究进展作一综述.     

甲磺酸伊马替尼治疗胃肠道间质瘤的疗效及安全性分析

胃肠道间质瘤(gastrointestinalStromal tumor,GIST)是最常见的消化道间质肿瘤,这些肿瘤通常存在酪氨酸受体激酶KIT(75%～80%)或PDGFRA(5%～10%)激活性突变[1].激活性突变使配体独立激活,然后激发KIT或PDG-FRA组成性激活介导的信号转导通路,从而发生不可控制的细胞增生,同时抑制细胞凋亡,最终GIST形成.GIST对传统的化疗和放疗高度耐药,在甲磺酸伊马替尼(imatinibmesvlate.Glivec,preyiotislv called STI571)出现以前,手术是治疗GIST的主要方式,但手术治疗往往并不足够,甚至完全切除肿瘤后,大部分晚期GIST患者还是出现复发,而出现复发和(或)转移的患者往往预后不良[2].GIST分子遗传学与靶向治疗方面的相互结合,使小分子激酶抑制剂伊马替尼治疗复发性或转移性胃肠道问质瘤,成为其他实体瘤靶向治疗的典范.到日前为此,甲磺酸伊马替尼在美国、中国及许多国家被批准用于不可切除和(或)转移性GIST治疗的一线药物.本文回顾性分析复旦大学附属肿瘤医院甲磺酸伊马替尼治疗的39例GIST患者,并就伊乌替尼疗效和安全性作一总结.     

KIT and platelet-derived growth factor receptor alpha tyrosine kinase gene mutations and KIT amplifications in human solid tumors.

PURPOSE: Mutated KIT and platelet-derived growth factor receptor alpha (PDGFRalpha) tyrosine kinases are the principal targets for imatinib mesylate in the treatment of gastrointestinal stromal tumors (GISTs). The frequency of activating KIT and PDGFRA gene mutations in most other histologic types of human cancer is not known. MATERIALS AND METHODS: KIT exons 9, 11, 13, and 17 and PDGFRA exons 11 and 17 of 334 human cancers were screened for mutations using sensitive denaturing high-performance liquid chromatography (DHPLC). In addition, all KIT exons from 9 to 21 of 115 tumors were screened. Thirty-two histologic tumor types were examined. Samples with abnormal findings in DHLPC were sequenced. Immunostaining for the KIT protein (CD117) was performed in 322 (96.4%) of the 334 cases. RESULTS: Of the 3,039 exons screened, only 17 had mutation. All 17 cases with either mutated KIT (n = 15) or PDGFRA (n = 2) were histologically GIST tumors, whereas none of the other histologic types of cancer (n = 316) harbored KIT or PDGFRA mutation. KIT immunostaining was rarely positive except in GISTs (18 of 18), small-cell lung cancer (10 of 30; 33%), and testicular teratocarcinoma (four of 17; 24%). Wild-type KIT gene amplification or chromosome 4 aneuploidy was common (seven of 12) in non-GIST tumors with strong KIT protein expression when studied with fluorescence in situ hybridization. CONCLUSION: Despite frequent KIT protein expression in some tumor types, KIT and PDGFRA gene mutations are uncommon in most human cancers. Cancer KIT expression is frequently associated with multiple copies of the wild-type KIT gene.     

SDHA loss of function mutations in a subset of young adult wild-type gastrointestinal stromal tumors

ABSTRACT: BACKGROUND: A subset of KIT/PDGFRA wild-type gastrointestinal stromal tumors (WT GIST) have been associated with alteration of the succinate dehydrogenase (SDH) complex II function. A recent report identified four non-syndromic, KIT/PDGFRA WT GIST harboring compound heterozygous or homozygous mutations in SDHA encoding the main subunit of the SDH complex II. METHODS: Next generation sequencing was applied on five pediatric and one young adult WT GIST, by whole exome capture and SOLiD 3-plus system sequencing. The putative mutations were first confirmed by Sanger sequencing and then screened on a larger panel of 11 pediatric and young adult WT GIST, including 5 in the context of Carney triad. RESULTS: A germline p.Arg31X nonsense SDHA mutation was identified in one of the six cases tested by SOLiD platform. An additional p.D38V missense mutation in SDHA exon 2 was identified by Sanger sequencing in the extended KIT/PDGFRA WT GIST patients cohort. Western blotting showed loss of SDHA expression in the two cases harboring SDHA mutations, while expression being retained in the other WT GIST tumors. Results were further confirmed by immunohistochemistry for both SDHA and SDHB, which showed a concurrent loss of expression of both proteins in SDHA-mutant lesions, while the remaining WT tumors showed only loss of SDHB expression. CONCLUSIONS: Germline and/or somatic aberrations of SDHA occur in a small subset of KIT/PDGFRA WT GISTs, outside the Carney's triad and are associated with loss of both SDHA and SDHB protein expression. Mutations of the SDH complex II are more particularly associated with KIT/PDGFRA WT GIST occurring in young adults. Although pediatric GIST consistently display alterations of SDHB protein expression, further molecular studies are needed to identify the crucial genes involved in their tumorigenesis.     

Biology of gastrointestinal stromal tumors.

Once a poorly defined pathologic oddity, in recent years, gastrointestinal stromal tumor (GIST) has emerged as a distinct oncogenetic entity that is now center stage in clinical trials of kinase-targeted therapies. This review charts the rapid progress that has established GIST as a model for understanding the role of oncogenic kinase mutations in human tumorigenesis. Approximately 80% to 85% of GISTs harbor activating mutations of the KIT tyrosine kinase. In a series of 322 GISTs (including 140 previously published cases) studied by the authors in detail, mutations in the KIT gene occurred with decreasing frequency in exons 11 (66.1%), 9 (13%), 13 (1.2%), and 17 (0.6%). In the same series, a subset of tumors had mutations in the KIT-related kinase gene PDGF receptor alpha (PDGFRA), which occurred in either exon 18 (5.6%) or 12 (1.5%). The remainder of GISTs (12%) were wild type for both KIT and PDGFRA. Comparative studies of KIT-mutant, PDGFRA-mutant, and wild-type GISTs indicate that there are many similarities between these groups of tumors but also important differences. In particular, the responsiveness of GISTs to treatment with the kinase inhibitor imatinib varies substantially depending on the exonic location of the KIT or PDGFRA mutation. Given these differences, which have implications both for the diagnosis and treatment of GISTs, we propose a molecular-based classification of GIST. Recent studies of familial GIST, pediatric GIST, and variant forms of GIST related to Carney's triad and neurofibromatosis type 1 are discussed in relationship to this molecular classification. In addition, the role of mutation screening in KIT and PDGFRA as a diagnostic and prognostic aid is emphasized in this review.     

Genetic aberrations of gastrointestinal stromal tumors

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal neoplasm in the gastrointestinal tract and is associated with mutations of the KIT or PDGFRA gene. In addition, other genetic events are believed to be involved in GIST tumorigenesis. Cytogenetic aberrations associated with these tumors thus far described include loss of 1p, 13q, 14q, or 15q, loss of heterozygosity of 22q, numeric chromosomal imbalances, and nuclear/mitochondrial microsatellite instability. Molecular genetic aberrations include loss of heterozygosity of p16(INK4A) and p14(ARF), methylation of p15(INK4B), homozygous loss of the Hox11L1 gene, and amplification of C-MYC, MDM2, EGFR1, and CCND1. GISTs in patients with neurofibromatosis type 1 appear to lack the KIT and PDGFRA mutations characteristic of GISTs and may have a different pathogenetic mechanism. Gene mutations of KIT or PDGFRA are critical in GISTs, because the aberrant versions not only are correlated with the specific cell morphology, histologic phenotype, metastasis, and prognosis, but also are the targets of therapy with imatinib and other agents. Furthermore, specific mutations in KIT and PDGFR appear to lead to differential drug sensitivity and may in the future guide selection of tyrosine kinase inhibitors. Activation of the receptor tyrosine kinases involves a signal transduction pathway whose components (mitogen-activated protein kinase, AKT, phosphoinositide 3-kinase, mammalian target of rapamycin, and RAS) are also possible targets of inhibition. A new paradigm of classification, integrating the standard clinical and pathological criteria with molecular aberrations, may permit personalized prognosis and treatment.     

Molecular analysis of secondary kinase mutations in imatinib-resistant gastrointestinal stromal tumors

Most gastrointestinal stromal tumors (GISTs) are associated with activating kinase mutation in KIT or platelet-derived growth factor receptor alpha (PDGFRA) gene, and imatinib has revolutionized the care of advanced GISTs. However, most patients gradually developed resistance to imatinib. We intend to identify the secondary kinase mutations in imatinib-resistant GISTs and to study the relationship between secondary kinase mutations and the clinical response to imatinib. Twelve advanced GIST patients, who have developed resistance to imatinib were included in this study. Paraffin-embedded pretreatment GIST specimens and progression lesions of the tumors after resistance to imatinib were analyzed for kinase mutations in exons 9, 11, 13, and 17 of KIT gene and exons of 10, 12, 14, and 18 of PDGFRA gene. Primary KIT mutations have been found in all but one of the primary tumors including one case harboring de novo double KIT exon 11 mutations. Secondary kinase mutations in KIT and PDGFRA were found in seven and 1 of 12 patients, respectively. Two patients harbored more than one secondary KIT mutations in different progression sites, and there are four types of clonal or polyclonal evolution being observed. The secondary PDGFRA exon 14 mutation H687Y is a novel mutation that has never been reported before. Acquired secondary kinase mutations are the most important cause of secondary imatinib resistance in advanced GISTs. The identification of secondary kinase mutations is important in the development of new therapeutic strategies.     

Protein kinase C-theta regulates KIT expression and proliferation in gastrointestinal stromal tumors

Oncogenic KIT or PDGFRA receptor tyrosine kinase mutations are compelling therapeutic targets in gastrointestinal stromal tumors (GISTs), and the KIT/PDGFRA kinase inhibitor, imatinib, is standard of care for patients with metastatic GIST. However, most of these patients eventually develop clinical resistance to imatinib and other KIT/PDGFRA kinase inhibitors and there is an urgent need to identify novel therapeutic strategies. We reported previously that protein kinase C-theta (PKCtheta) is activated in GIST, irrespective of KIT or PDGFRA mutational status, and is expressed at levels unprecedented in other mesenchymal tumors, therefore serving as a diagnostic marker of GIST. Herein, we characterize biological functions of PKCtheta in imatinib-sensitive and imatinib-resistant GISTs, showing that lentivirus-mediated PKCtheta knockdown is accompanied by inhibition of KIT expression in three KIT+/PKCtheta+ GIST cell lines, but not in a comparator KIT+/PKCtheta- Ewing's sarcoma cell line. PKCtheta knockdown in the KIT+ GISTs was associated with inhibition of the phosphatidylinositol-3-kinase/AKT signaling pathway, upregulation of the cyclin-dependent kinase inhibitors p21 and p27, antiproliferative effects due to G(1) arrest and induction of apoptosis, comparable to the effects seen after direct knockdown of KIT expression by KIT short-hairpin RNA. These novel findings highlight that PKCtheta warrants clinical evaluation as a potential therapeutic target in GISTs, including those cases containing mutations that confer resistance to KIT/PDGFRA kinase inhibitors.     

Long-term follow-up results of the multicenter phase II trial of regorafenib in patients with metastatic and/or unresectable GI stromal tumor after failure of standard tyrosine kinase inhibitor therapy

BackgroundThis investigator-initiated trial provided the justification for the phase III GRID study resulting in worldwide regulatory approval of regorafenib as a third-line therapy for patients with metastatic gastrointestinal stromal tumors (GIST). We report the genotype analyses, long-term safety, and activity results from this initial trial of regorafenib in GIST.Patients and methodsThe trial was conducted between February 2010 and January 2014, among adult patients with metastatic GIST, after failure of at least imatinib and sunitinib. Patients received regorafenib orally, 160 mg once daily, days 1–21 of a 28-day cycle. Clinical benefit rate (CBR), defined as complete or partial response (PR), or stable disease lasting ≥16 weeks per RECIST 1.1, progression-free survival (PFS), overall survival (OS), long-term safety data, and metabolic response by functional imaging were assessed.ResultsThirty-three patients received at least one dose of regorafenib. The median follow-up was 41 months. CBR was documented in 25 of 33 patients [76%; 95% confidence interval (CI) 58% to 89%], including six PRs. The median PFS was 13.2 months (95% CI 9.2–18.3 months) including four patients who remained progression-free at study closure, each achieving clinical benefit for more than 3 years (range 36.8–43.5 months). The median OS was 25 months (95% CI 13.2–39.1 months). Patients whose tumors harbored a KIT exon 11 mutation demonstrated the longest median PFS (13.4 months), whereas patients with KIT/PDGFRA wild-type, non-SDH-deficient tumors experienced a median 1.6 months PFS (P < 0.0001). Long-term safety profile is consistent with previous reports; hand–foot skin reaction and hypertension were the most common reasons for dose reduction. Notably, regorafenib induced objective responses and durable benefit in SDH-deficient GIST.ConclusionsLong-term follow-up of patients with metastatic GIST treated with regorafenib suggests particular benefit among patients with primary KIT exon 11 mutations and those with SDH-deficient GIST. Dose modifications are frequently required to manage treatment-related toxicities.Clinical trial numberNCT01068769.     

A novel germline SDHB mutation in a gastrointestinal stromal tumor patient without bona fide features of the Carney–Stratakis dyad

Gastrointestinal stromal tumors (GISTs) are the most common mesenchyme neoplasms of the gastrointestinal tract. Gain-of-function somatic mutations of the KIT or PDGFRA genes represent the most prevalent molecular alterations in GISTs. In Carney-Stratakis dyad, patients portray germline mutations of the succinate dehydrogenase subunits B (SDHB), C (SDHC) and D (SDHD) and develop multifocal GISTs and multicentric paragangliomas (PGLs). We herein report a novel germline SDHB mutation (c.T282A--Ile44Asn) occurring in a 26 years-old patient diagnosed with a spindle cell intermediate risk GIST that did not present KIT/PDGFRA/BRAF gene mutations. Further analyses revealed loss of the wild-type SDHB allele and complete loss of SDHB expression in the tumor tissue. After genetic screening of other family members, we detected in the patient's mother a SDHB mutation without any clinical/laboratorial evidence of GIST or PGL. Altogether, our findings (germline SDHB mutation with absence of PGL in the index case and of GIST and/or PGL in his mother) raise the possibility that this familiar setting corresponds to an incomplete phenotype of the Carney-Stratakis dyad.     

Kinase mutations and imatinib response in patients with metastatic gastrointestinal stromal tumor.

PURPOSE: Most gastrointestinal stromal tumors (GISTs) express constitutively activated mutant isoforms of KIT or kinase platelet-derived growth factor receptor alpha (PDGFRA) that are potential therapeutic targets for imatinib mesylate. The relationship between mutations in these kinases and clinical response to imatinib was examined in a group of patients with advanced GIST. PATIENTS AND METHODS: GISTs from 127 patients enrolled onto a phase II clinical study of imatinib were examined for mutations of KIT or PDGFRA. Mutation types were correlated with clinical outcome. RESULTS: Activating mutations of KIT or PDGFRA were found in 112 (88.2%) and six (4.7%) GISTs, respectively. Most KIT mutations involved exon 9 (n = 23) or exon 11 (n = 85). All KIT mutant isoforms, but only a subset of PDGFRA mutant isoforms, were sensitive to imatinib, in vitro. In patients with GISTs harboring exon 11 KIT mutations, the partial response rate (PR) was 83.5%, whereas patients with tumors containing an exon 9 KIT mutation or no detectable mutation of KIT or PDGFRA had PR rates of 47.8% (P =.0006) and 0.0% (P <.0001), respectively. Patients whose tumors contained exon 11 KIT mutations had a longer event-free and overall survival than those whose tumors expressed either exon 9 KIT mutations or had no detectable kinase mutation. CONCLUSION: Activating mutations of KIT or PDGFRA are found in the vast majority of GISTs, and the mutational status of these oncoproteins is predictive of clinical response to imatinib. PDGFRA mutations can explain response and sensitivity to imatinib in some GISTs lacking KIT mutations.