C-kit Gene Abnormalities in Gastrointestinal Stromal Tumors (Tumors of Interstitial Cells of Cajal)

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the GI tract, and expresses KIT and CD34 in most cases. Gain-of-function mutation of the c-kit proto-oncogene has been described, but its significance in GIST has not yet been fully evaluated. Mutation in exon 11 of the c-kit gene was determined by both polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis and direct sequencing in primary and metastatic GISTs and esophageal leiomyomas in Japanese subjects. C-kit gene mutation was identified in 15 of 48 primary GISTs (31%), four of seven metastatic GISTs, but none of the leiomyomas. Three mutations were mis-sense point mutations, and 16 were in-frame deletions of 3–48 bp. C-kit gene mutation was observed equally in low- and high-risk groups, and was not related to any clinical and pathologic factors, phenotypes or Ki-67 labeling index (LI) of tumor cells. In five of 15 deletion mutations (four in primary tumors and one in a metastatic tumor), the mutations were present at the distal location of exon 11 of the c-kit gene, which was a minor mutation in previous reports from Finland and the USA. C-kit gene mutations in GIST are not always related to a poor prognosis, but further comparative studies are necessary in Western and Japanese populations.     

Mutations in c-kit gene exons 9 and 13 in gastrointestinal stromal tumors among Japanese.

Gain-of-function mutation in c-kit proto-oncogene exon 11 has been described in about 20 -- 50% of gastrointestinal stroma tumor (GIST). Recently, additional mutational hot-spots in exon 9 and exon 13 of the c-kit gene have been reported in GISTs without mutations of exon 11, but a subsequent report in a Western population indicated that only a small portion of GISTs (eight of 200 GISTs, 4%) showed mutations in these regions. In this study, we evaluated mutations in exon 9 and exon 13 of the c-kit gene by both polymerase chain reaction-single strand conformation polymorphism analysis and direct sequencing in 48 GISTs in a Japanese population, for which the clinicopathological and immunohistochemical features and mutations in exon 11 had previously been reported. C-kit gene mutation in exon 9, representing insertion of GCC TAT, was identified in only 4 of 48 GISTs (8%), and none of the GISTs had mutations in exon 13. All four GISTs with mutation in exon 9 were high-risk, and the patients died of multiple tumor metastasis. Mutations in exon 9 and exon 13 of the c-kit gene were also rare events in Japanese GISTs and were related to a poor prognosis. These results in Japanese are consistent with those in Western populations, although a preferential occurrence of GISTs with exon 9 mutation in the small intestine, which was suggested in a previous report, was not observed.     

DOG-1在胃肠道间质瘤中的表达及其临床意义

目的研究DOG-1在胃肠道间质瘤(GIST)中的表达及其临床意义。方法应用免疫组织化学方法检测61例GIST中DOG-1的表达,并与CD117标记进行比较观察,分析DOG-1与GIST各临床病理特征的关系。结果CD117和DOG-1在极低度及低度危险性GIST组织中表达率分别为95.2%(20/21)和90.5%(19/21);在中度及高度危险性GIST中CD117和DOG-1阳性表达率分别为100.0%(40/40)和97.5%(39/40)。CD117表达与DOG-1无关;DOG-1表达与GIST发生部位、肿瘤大小、分级和年龄无关;DOG-1阴性与GIST复发及转移显著相关(P<0.01)。结论DOG-1可作为GIST诊断和预后判断的潜在参考指标。     

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。      

巢蛋白(Nestin)在胃肠道间质瘤组织中的表达及其临床意义

目的　通过检测胃肠道间质瘤 (GIST )组织中巢蛋白 (nestin)的表达 ,探讨nestin在GIST的诊断、鉴别诊断及起源中的意义。方法　应用免疫组织化学技术EnVision微波二步法 ,检测 94例GIST (良性 44例 ,恶性 5 0例 )组织中nestin蛋白的表达 ,并与平滑肌瘤和平滑肌肉瘤进行对照研究。结果　GIST组织中nestin的阳性表达率为 95 .7% ( 90 /94) ,良、恶性组nestin的阳性率分别为 97.7% ( 4 3 /4 4)、94.0 % ( 4 7/5 0 )。 2组的表达水平无显著性差异 (P >0 .0 5 )。平滑肌瘤和平滑肌肉瘤nestin表达均阴性。结论　Nestin作为胃肠道间质瘤的 1种特异而敏感的新标志物 ,对GIST的诊断及鉴别诊断有重要意义 ,但不能作为GIST分化程度的指标 ,同时提示GIST可能起源于向卡哈尔细胞 (ICC )表型分化的干细胞。     

胃肠道间质瘤中Maspin表达及其与p53表达的相关性

目的探讨maspin表达对胃肠道间质瘤（GIST）生物学行为的预测、预后的评估作用,及其与p53表达的相关性。方法选取42例GIST标本,进行maspin和p53免疫组织化学染色,分析maspin表达与p53表达及GIST临床病理参数的关系。结果胃肠道间质瘤中maspin阳性表达率为64.3%（26/42）,与患者性别、年龄及肿瘤部位、组织学类型无显著相关性（P〉0.05）;与肿瘤侵袭危险性及p53表达均呈负相关性（P〈0.05）;39例获得随访的GIST患者中,maspin表达与其生存率无显著相关性（P〉0.05）。结论 maspin和p53联合检测,有助于预测GIST生物学行为及预后判断。     

Clinico-Pathological Characteristics and Mutational Analysis of Gastrointestinal Stromal Tumors from India: A Single Institution Experience

Background: Gastrointestinal stromal tumor (GIST) is the most common type of mesenchymal neoplasm of gastrointestinal tract. The incidence of GIST in India is not known and its treatment strategy in our country is largely derived from studies in other global populations. Some of the most important features of this type of cancer include its size, site of origin, mitotic index, histology and Immunohistochemistry. In this report we have studied these parameters in the Indian GIST patients presenting at our center. Additionally, we have also studied the mutational spectrum of these GISTs by next generation sequencing. Methods: Thirty one Indian patients of GIST were enrolled in this study and information regarding age, gender, tumor location and size was collected from their records. Immunohistochemistry studies were performed by the pathologist. Mutational analysis of these samples was performed by next generation sequencing. Results and Discussion: The most common site of GIST occurrence in our study was stomach. The tumor size for all 31 patients ranged between 0.6 cms to 20 cms. A spindle-cell pattern was present in 24 out of 31 of the cases. 29 out of 31 subjects were positive for CD117 expression. C-KIT was the most highly mutated gene indentified in our patients. Apart from these findings we observed many similarities as well as dissimilarities between the results of our study and literature published previously. Conclusions: The dissimilarities in the results of our study and published literature could be attributed to the genetic or ethnic differences that exist between the Indian population and other global populations. The results of our study warrant a need to conduct studies of GIST in a much larger population of India. Such large scale studies may also help in better treatment and/or prevention of GIST in developing countries like India.     

Key Issues in the Clinical Management of Gastrointestinal Stromal Tumors: An Expert Discussion

After the revelation of kinase targeting with orally available small molecules, the use of imatinib in chronic myelogenous leukemia and in gastrointestinal stromal tumor (GIST) has now become commonplace and just two of many examples of the use of kinase inhibitors in cancer. In this article, we discuss important practice points that may impact upon questions of therapy of primary and metastatic GIST, with the hope that the questions addressed in this rare solid tumor can serve as examples of what can be achieved with kinase-directed therapies in other cancers. We present cases that highlight some of the key issues in GIST management and afterward discuss both points of consensus and controversial issues in what is now recognized as one of the most common forms of sarcoma.

Implications for Practice:

The treatment of gastrointestinal stromal tumor (GIST) has become sophisticated with the availability of three approved agents in many countries and 15 years of experience with primary and metastatic disease. Important lessons from tyrosine-kinase inhibitors in GIST can be gleaned from this experience and will impact implementation of similar agents for other cancers.     

Gastrointestinal Stromal Tumors: 10-Year Experience in Cancer Center—The Ottawa Hospital (TOH)

(1) Background: The management of gastrointestinal stromal tumors (GIST) has significantly evolved over the last two decades, with the introduction of tyrosine kinase inhibitors (TKI). We aim to report 10 years of experience of GIST management at a regional cancer center in Canada. (2) Methods: We retrospectively analyzed the records of 248 consecutive patients diagnosed with GIST between 2011 and 2021. We describe the clinical and pathological data, management, and outcome, including survival. (3) Results: The most common GIST sites were the stomach 63% (156), followed by the small bowel 29% (73). At diagnosis, 83% (206) of patients had localized disease (stage I–III). According to the modified National Institutes of Health consensus criteria (NIH) for GIST, around 45% (90) had intermediate or high-risk disease. Most patients, 86% (213), underwent curative surgical resection. Forty-nine patients received adjuvant imatinib, while forty-three patients had advanced disease and received at least one line of TKI. With a median follow-up of 47 months, the 5-year recurrence-free survival (RFS) rates for very low and low risk were 100% and 94%, respectively, while those for intermediate and high risk were 84% and 51%, respectively. The 5-year overall survival (OS) rates for very low and low risk were 100% and 94%, while intermediate, high risk, and advanced were 91%, 88%, and 65%, respectively. Using the Kaplan–Meier method, there were statistically significant differences in RFS and OS between NIH risk groups, p < 0.0005. In univariate analysis, ECOG, site, mitosis, secondary malignancy, and size were predictors for OS. High mitosis and large size (>5 cm) were associated with worse RFS. (4) Conclusions: Curative surgical resection remains the gold standard management of GIST. Our results are comparable to the reported literature. Further research is needed to explore histology’s role in risk stratification and initiating adjuvant TKI.     

41例胃肠间质瘤c-Kit及PDGFRa基因突变分析

[目的]探讨胃肠间质瘤（GIST）c-Kit、PDGFRa基因突变特点。[方法]收集41例GIST石蜡标本,采用直接测序法检测c-Kit外显子9、11、13、17,PDGFRa外显子12、18突变状态。[结果]41例GIST样本中34例（82.9%）检测到c-Kit或PDGFRa突变。其中c-Kit外显子9突变6例（14.6%）,外显子11突变24例（58.5%）,外显子13突变2例（4.9%）,PDGFRa外显子18突变2例（4.9%）。c-Kit外显子9突变均发生在小肠,PDGFRa外显子18突变则主要见于胃。小肠间质瘤中c-Kit外显子9突变型占31.6%,显著高于其它部位（P〈0.05）,而外显子11突变型占36.8%,显著低于其它部位（P〈0.05）。[结论]c-Kit/PDGFRa基因突变类型与GIST发生部位有关。约1/3小肠GIST患者存在c-Kit外显子9突变,在选择靶向药物治疗前应进行基因突变检测。     

Roles of mTOR and p-mTOR in Gastrointestinal Stromal Tumors

Objective: This study aimed to examine the relationship between expression of mammal target of rapamycin(mTOR) and phosphorylation of mTOR (p-mTOR) protein in the PI3K/Akt/mTOR signaling pathways ingastrointestinal stromal tumors and relatiuonships with clinical factors. Methods: Immunohistochemistry wasused to detect the expression of the associated proteins mTOR, p-mTOR, and phosphorylation of the tumorsuppressor genes PTEN, P27, VEGF, and EGFR in 40 cases of gastrointestinal stromal tumors, with divisioninto a very low and low risk group as well as a moderate and high risk group. Results: The positive rate ofmTOR and p-mTOR was significantly increased in the moderate and high risk group compared with the verylow and low risk group. The difference was statistically significant (P<0.05). When grouped according to size, thepositive mTOR expression rate exhibited a statistical difference (P<0.05), which was significantly increased inthe group of tumors larger than 5 cm. The difference in the positive mTOR and p-mTOR expression rate exhibitno statistical significance among the PTEN, P27, VEGF, and EGFR expression subgroups (P>0.05). Conclusion:The different expressions of mTOR and p-mTOR in the signal transduction pathway of gastrointestinal stromaltumor in the different degree-of-risk groups suggested that the mTOR and p-mTOR of the signal transductionpathway serve an important function in the occurrence and development of gastrointestinal stromal tumors.     

胃肠道间质瘤中PCNA和bcl-2蛋白的表达及临床意义

目的探讨胃肠道间质瘤(gastrointestinalstromaltumor,GIST)中增殖细胞核抗原(PCNA)和bcl-2蛋白的表达与其发生及恶性转化的关系。方法采用免疫组化SP法及彩色病理图像分析系统检测68例GIST组织中PCNA和bcl-2蛋白的表达。结果68例GIST中,PCNA均呈阳性表达,其平均灰度值在良性组为144.95±3.37,潜在恶性组为139.54±4.91,恶性组为135.71±6.11,依次递减,即阳性表达水平逐渐增强,三者两两比较,差异均有显著性(P<0.05)。68例GIST中,bcl-2阳性表达者35例(51.47%),其平均灰度值在良性组为144.32±3.80,潜在恶性组为142.35±12.30,恶性组为140.35±12.06,三者两两比较,差异无显著性(P>0.05)。GIST中PCNA和bcl-2表达无明显相关性(P>0.05)。结论细胞的增殖与凋亡的失衡是GIST发生恶性转化的重要机制之一。PCNA检测有助于判断GIST的性质;bcl-2在GIST早期阶段就参与了肿瘤的发生发展,但不能作为判断良恶性的指标。     

Circulating cKIT and PDGFRA DNA indicates disease activity in Gastrointestinal Stromal Tumor (GIST)

This prospective trial aimed to investigate whether tumor-specific cKIT and PDGFRA mutations can be detected and quantified in circulating tumor (ct)DNA in patients with active GIST, and whether detection indicates disease activity. We included 25 patients with active disease and cKIT or PDGFRA mutations detected in tissue. Mutant ctDNA was detected in the peripheral blood plasma using allele-specific ligation (L-)PCR and droplet digital (d)PCR. CtDNA harboring tumor-specific cKIT or PDGFRA mutations was detected at least once in 16 out of 25 patients using L-PCR (64%) and in 20 out of 25 patients with dPCR (80%). Using dPCR, the absolute numbers of ctDNA fragments (DNA copies/ml) and the mutant allele frequency (MAF; in percent of wild-type control) strongly correlated with tumor size expressed as RECIST1.1 sum of diameter (SOD) in mm (ρ = 0.3719 and 0.408, respectively, p < 0.0001) and response status (ρ = 0.3939 and 0.392, respectively, p < 0.0001 and p < 0.001). Specificity of dPCR for detection of progression was 79.2% with a sensitivity of 55.2% and dPCR discriminated CR from active disease with a specificity of 96% and s sensitivity of 44.7%. With L-PCR, correlations of MAF with tumor size and response status were less prominent. Serial ctDNA measurement reflected individual disease courses over time. Targeted panel sequencing of four patients detected additional driver mutations in all cases and secondary resistance mutations in two cases. Thus, ctDNA indicates disease activity in patients with GIST and should be incorporated as companion biomarker in future prospective trials.     

Histomorphology and Immunohistochemistry of Gastrointestinal Stromal Tumors in a Malaysian Population

Purpose: To study histomorphological and immunohistochemical patterns of gastro-intestinal stromal tumours (GISTs) in Malaysia. Materials and Methods: A total of 29 GIST cases from Hospital Tuanku Ja’afar, Seremban ,were studied retrospectively over a period of 10 years from January 2002 to December 2011. Patient demographic data like age, sex and etnicity were collected. Tumour characteristics like site, maximum dimension and specimen type were analysed. Evaluation was according to established criteria into very low, low, intermediate and high-risk categories. Immunohistochemical characteristics were also analysed. Results: The mean age of patients was 59.7 years. Males (59%) were found to be more commonly affected than females (41%). The Chinese (45%) were commonly affected than Malays (41%), and Indians (10%). The most common symptom was pain in the abdomen (13.8%). More than half of the cases were seen in stomach (53%). The tumour size ranged from 1.5 cm to 17 cm with a mean of 6.94cm. Microscopic findings revealed that the spindle cell type was the most common (76%). It was observed that the majority of the cases (48%) were categorised in the intermediate risk group. Immunohistochemical staining showed positivity for CD117 (78.6%), CD34 (71.4%), vimentin (86.2%), S-100 (27.6%), SMA (35.7%), PKC THETA (46.4%) and PDGRFA (67.9%).