C-kit Mutation Research Articles

The loss or absence of minimal residual disease of

No consensus has been reached on the relationship between CBFB-MYH11 copies and prognosis. Of 1525 acute myeloid leukemia (AML) patients, 58 with CBFB-MYH11-positive AML (16/58 patients with c-kit mutation) were retrospectively analyzed with a median follow-up duration of 29.8 (range: 4.8-74.4) months. Of these, 25/58 (43.1%) patients underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT), 10 of whom had the c-kit mutation. Of the 33 patients who did not undergo allo-HSCT, recurrence in patients with CBFB-MYH11/ABL level >0.1% at any time after two consolidation cycles was significantly higher than in patients with CBFB-MYH11/ABL level <0.1% (61.9% vs. 0%, P=0.001); further, the 3-year relapse-free survival (RFS; 31.4% vs. 100%, P=0.004) and event-free survival (EFS; 33.1% vs. 100%, P=0.004) were significantly decreased in patients with CBFB-MYH11/ABL level >0.1% at any time after two consolidation cycles. The 3-year RFS and EFS rates were lower in patients who did not receive allo-HSCT than in those who did (31.4% vs 84.6%, P=0.000; 31.4% vs. 80.8%, P=0.001). CBFB-MYH11-positive AML patients with CBFB-MYH11/ABL level >0.1% at any time after two cycles of consolidation had poor prognoses, and allo-HSCT could improve their survival.

Allogeneic hematopoietic stem cell transplantation can improve the prognosis of high-risk pediatric t(8;21) acute myeloid leukemia in first remission based on MRD-guided treatment

BackgroundPediatric acute myeloid leukemia (AML) with t(8;21) (q22;q22) is classified as a low-risk group. However, relapse is still the main factor affecting survival. We aimed to investigate the effect of allogeneic hematopoietic stem cell transplantation (allo-HSCT) on reducing recurrence and improving the survival of high-risk pediatric t(8;21) AML based on minimal residual disease (MRD)-guided treatment, and to further explore the prognostic factors to guide risk stratification treatment and identify who will benefit from allo-HSCT.MethodsOverall, 129 newly diagnosed pediatric t(8;21) AML patients were included in this study. Patients were divided into high-risk and low-risk group according to RUNX1-RUNX1T1 transcript levels after 2 cycles of consolidation chemotherapy. High-risk patients were divided into HSCT group and chemotherapy group according to their treatment choices. The characteristics and outcomes of 125 patients were analyzed.ResultsFor high-risk patients, allo-HSCT could improve 5-year relapse-free survival (RFS) rate compared to chemotherapy (87.4% vs. 61.9%; P = 0.026). Five-year overall survival (OS) rate in high-risk HSCT group had a trend for better than that in high-risk chemotherapy group (82.8% vs. 71.4%; P = 0.260). The 5-year RFS rate of patients with a c-KIT mutation in high-risk HSCT group had a trend for better than that of patients with a c-KIT mutation in high-risk chemotherapy group (82.9% vs. 75%; P = 0.400). Extramedullary infiltration (EI) at diagnosis was associated with a high cumulative incidence of relapse for high-risk patients (50% vs. 18.4%; P = 0.004); allo-HSCT can improve the RFS (P = 0.009).Conclusionsallo-HSCT can improve the prognosis of high-risk pediatric t(8;21) AML based on MRD-guided treatment. Patients with a c-KIT mutation may benefit from allo-HSCT. EI is an independent prognostic factor for high-risk patients and allo-HSCT can improve the prognosis.

High frequency of c-KIT genetic variants in exons 9, 11, 13 and 17 and PDGFRA in exon 18 in gastric GIST tumors.

e23525 Background: Gastrointestinal stromal tumors (GIST) are rare malignant mesenchymal neoplasms of the gastrointestinal tract, the diagnosis and treatment of which is associated with the presence of mutations in the c-KIT and PDGFRA genes. Purpose of this study was molecular genetic genotyping of GIST according to clinically significant exons of the c-KIT and PDGFRA genes. Methods: The study included patients with an immunohistochemically confirmed diagnosis of GIST who underwent treatment in the RRIO, Rostov-on-Don, for the period 2018-2019 (n = 20, median age 63.5 years, men/women–10 people each, gastric tumors). DNA was isolated from FFPE tissue using the GeneJET FFPE DNA Purification Kit, USA. The presence of mutations in exons 9, 11, 13 and 17 of c-KIT and exon 18 of PDGFRA was detected by Sanger sequencing. Results: Activating mutations in exon c-KIT were detected in 10 ps, including one substitution p.V560E and 4 deletions – p.V559_E561del, p.M552_V555delMYEV, p.W557_V559 &gt; F and p.W557_V559 &gt; C. These mutations cause sensitivity to imatinib. Pathogenic mutations were detected in PDGFRA exon 18: an activating deletion p.I843_D846delIMHD (2 ps) and a substitution p.D842Y, which determines imatinib resistance (2 ps). Thus, 20% of GIST cases are promising for obtaining avapritinib, the first FDA approved drug in 2020 for patients with GIST with a mutation in PDGFRA exon 18. In addition, neutral genetic variants were revealed: in 17 exon c-KIT in 16 patients, benign rs1008658, in PDGFRA 18 exon – rs3830355 (3 ps) and silent mutation p.V824V (3 ps). Conclusions: Genotyping of c-KIT and PDGFRA identified 12 types of clinically significant mutations and, in 80% of cases, the carriage of benign polymorphisms and / or SNPs of unknown clinical significance. As a result, 70% of patients from the South of Russia with GIST may be sensitive to treatment with imatinib and/or avapritinib.

Volumetric Optoacoustic Tomography Differentiates Myocardial Remodelling.

Myocardial healing following myocardial infarction (MI) is a complex process that is yet to be fully understood. Clinical attempts in regeneration of the injured myocardium using cardiac stem cells faced major challenges, calling for a better understanding of the processes involved at a more basic level in order to foster translation. We examined the feasibility of volumetric optoacoustic tomography (VOT) in studying healing of the myocardium in different models of MI, including permanent occlusion (PO) of the left coronary artery, temporary occlusion (ischemia-reperfusion-I/R) and infarcted c-kit mutants, a genetic mouse model with impaired cardiac healing. Murine hearts were imaged at 100Hz frame rate using 800nm excitation wavelength, corresponding to the peak absorption of indocyanine green (ICG) in plasma and the isosbestic point of haemoglobin. The non-invasive real-time volumetric imaging capabilities of VOT have allowed the detection of significant variations in the pulmonary transit time (PTT), a parameter affected by MI, across different murine models. Upon intravenous injection of ICG, we were able to track alterations in cardiac perfusion in I/R models, which were absent in wild-type (wt) PO or kitW/kitW-v PO mice. The wt-PO and I/R models further exhibited irregularities in their cardiac cycles. Clear differences in the PTT, ICG perfusion and cardiac cycle patterns were identified between the different models and days post MI. Overall, the results highlight the unique capacity of VOT for multi-parametric characterization of morphological and functional changes in murine models of MI.

Bone mineral density in patients with systemic mastocytosis: correlations with clinical and histopathological features.

Systemic mastocytosis (SM) is a heterogeneous haematological entity characterised by proliferation of mast cells. Skeletal abnormalities of SM include osteolysis, osteopenia and osteoporosis but also osteosclerosis. A routinely used modality to assess bone density is dual-energy x-ray absorptiometry (DXA). The present study sought to elucidate possible associations between DXA findings with both clinical and bone marrow biopsy findings in SM. Patient records of the local oncology and haematology department from 2007 to 2018 were screened for patients with SM. Overall, 39 patients (18 women and 21 men) with sufficient DXA images and clinical data were identified. We evaluated cKit mutation, tryptase level in serum, alkaline phosphatase, calcium level in serum, haemoglobin level, leucocytes and thrombocytes. Bone marrow biopsies were also evaluated. There were no significant differences between the different bone marrow patterns and in regard of cKit mutations. Significant lower bone mineral density (BMD) - T-score and Z-score values were identified for the indolent type compared to aggressive type. Correlation analysis revealed an association between BMD and tryptase level (r=0.35, p=0.049), mast cell proportion in bone marrow biopsy (r=0.45, p=0.01) and with the years since diagnosis (r=-0.42, p=0.02). Moreover, the correlations differed between the indolent and aggressive type. DXA findings are associated with clinical and bone marrow biopsy parameters in SM. A positive association with tryptase level and mast cell amount in bone marrow biopsies was identified. This corroborates the usefulness of DXA in SM beyond the sole assessment of osteopenia and osteoporosis.

Analysis of C-Kit Exon 9, Exon 11 and BRAFV600E Mutations Using Sangers Sequencing in Gastrointestinal Stromal Tumours.

BackgroundGastrointestinal stromal tumors (GIST) are the most common mesenchymal neoplasms in the gastrointestinal (GI) tract. The mutation of C-KIT is considered to be the crucial step in the tumorigenesis. Targeted therapies are being developed focusing these mutations. Various exon mutations of GIST responded in varied patterns to this targeted therapy. This study was carried out to evaluate the C-KIT exon 11, exon 9 and BRAF V600E mutations among GIST specimens.MethodsThis retrospective study was carried out among 20 DNA extracted specimens from paraffin blocks of GIST received in our tertiary teaching institution for a period of three years. DNA sequencing was carried out for mutational analyses on C-KIT exon 9, C-KIT exon 11 and BRAF V600E genes using Sanger sequencing.ResultsHistologically, majority of the tumors had spindle cell morphology. About 19 cases were positive for CD117. The analysis of type of mutations showed that three cases carried Exon 11 and three cases carried Exon 9 mutations. BRAF V600E mutation was seen in one case.ConclusionIt is essential to conduct molecular studies on GISTs in order to get a clear understanding of the pathogenesis and behavior pattern. This will also help in designing targeted therapies and assessing recurrence. With the advent of rapidly evolving personalized therapy, the evaluation of genetic mutations is essential for diagnosis and prognostic value.

Clinical Analysis of Primary Pulmonary Lymphoepithelioma-like Carcinoma in 8 Patients

背景与目的淋巴上皮瘤样癌为罕见的上皮肿瘤，多来源于鼻咽部，也发生在前肠起源器官，如肺、胃、唾液腺和胸腺。原发性肺淋巴上皮瘤样癌（primary pulmonary lymphoepithelioma-like carcinoma, PPLELC）是一种罕见的非小细胞肺癌（non-small cell lung cancer, NSCLC），约占肺癌的0.9%。本文目的在于探讨PPLELC的临床病理特点、治疗方法以及预后情况。方法回顾性分析湖南省肿瘤医院2013年10月-2016年6月收治的PPLELC患者8例，对其临床资料及预后进行临床分析，以深入研究这种罕见的肺癌亚型。结果8例患者中，62.5%（5/8）为女性，中位年龄为51.5岁（41岁-64岁），大多数（87.5%）患者不吸烟，50.0%患者无症状，约37.5%为Ⅰ期，50.0%为Ⅲ期，12.5%为Ⅳ期。PPLELC的典型病理特征与未分化的鼻咽癌相同，其特点是分化较差的肿瘤细胞，具有大的泡状核和核仁突出，呈合胞体生长，伴有淋巴细胞浸润。免疫表型：癌细胞P63（100.0%, 6/6）、CK5/6（100.0%, 5/5）、CK（100.0%, 5/5）阳性。对8例患者的程序性死亡配体-1（programmed cell death-ligand 1, PD-L1）表达进行了检测，当≥5%的细胞膜染色时定义为PD-L1阳性，PD-L1表达频率为50.0%（4/8），肿瘤细胞阳性比例分数（tumor proportion score, TPS）波动在20.0%-70.0%。3例行表皮生长因子受体（epidermal growth factor receptor, EGFR）基因突变检测，结果呈阴性；2例行EML4-ALK融合基因检测，结果呈阴性；1例行KRAS、B-raf、C-kit、HER2、VEGFR1、VEGFR2检测，结果示KRAS野生型，B-raf、C-kit无突变，HER2、VEGFR1、VEGFR2中等表达。所有患者均接受了手术治疗，其中接受了辅助化疗者5例，其中Ib期2例，Ⅲa期2例，Ⅳ期1例；辅助放化疗者1例，分期为Ⅲa期，接受了新辅助化疗者1例，分期为Ⅲa期。截止至随访截止期，所有患者均存活，中位存活时间为57个月，3年和5年总生存率（overall survival, OS）分别为87.5%和50.0%；无病生存率（disease-free survival, DFS）分别为87.5%和50.0%。结论PPLELC是一种罕见但独特的NSCLC亚型，具有明显的临床病理学特征，通常发生于年轻的非吸烟患者，无性别倾向，并与EB病毒（Epstein-Barr virus, EBV）感染有关，组织形态及免疫组化是诊断的主要手段。大多数患者缺乏EGFR和ALK等常见基因突变，提示这些基因的突变与PPLELC的发生无关。PD-1和PD-L1可能是潜在的治疗靶点。与其他类型的NSCLC相比，大多数患者处于早期或局部晚期，预后较好。目前还没有针对这种罕见肿瘤的标准化治疗方案。早期以手术切除为主，中晚期或转移阶段则采用手术、化疗、放疗等多种治疗方式。由于其发病率低，为了确定其生物学特性和最佳治疗方案，还需要进一步的研究。

Outcome of Core Binding Factor Acute Myeloid Leukemia by Receptor Tyrosine Kinase Mutation

BackgroundCore binding factor acute myeloid leukemia (CBF-AML) encodes 2 recurrent cytogenetic abnormalities, t(8;21) and inv(16), which carries an overall good prognosis. However, some patients will develop a relapse. We sought define the unfavorable group of CBF-AML by analysis of (c-KIT and FLT3-ITD) and to correlate them with treatment outcome. Patients and MethodsWe performed a prospective study of 70 patients with CBF-AML diagnosed and managed at the medical oncology department of the (National Cancer Institute), Cairo University, with analysis of c-KIT and FLT3 mutations. All patients had received “3 + 7” induction, followed by 3 to 4 courses of high-dose cytarabine consolidation. The institutional review board approved the present study. ResultsThe median patient age was 31 years (range, 18-60 years), with a male/female ratio of 4:3. Of the 70 patients, 42 (60%) had t(8;21) and 28 had inv(16) (40%). c-KIT mutations (exons 8 and 17) were detected in 10 of 52 tested patients, and FLT3-ITD was detected in 3 of 70 patients. Patients with inv(16) experienced more lymphadenopathy and splenomegaly, had a higher median initial leukocyte count. Hepatitis C antibody positivity (8 of 42) was exclusively present in patients with t(8;21). The median overall survival (OS) was 19.5 months, and the median disease-free survival (DFS) was not reached. Patients with inv(16) had near-significant (P = .07) better DFS than patients with t(8;21). c-KIT mutations had no significant effect on OS or DFS. However, reverse tyrosine kinase mutations had a negative effect on DFS but not OS (P = .04). ConclusionCBF-AML with reverse tyrosine kinase mutation conveys a worse prognosis. Hepatitis C virus antibody positivity might be associated with t(8;21) AML and inv(16) with more extramedullary disease.

The prognostic value of cloned genetic mutations detected by second-generation sequencing in RUNX1-RUNX1T1 positive acute myeloid leukemia patients receiving intensive consolidation therapy

目的探讨基于二代测序检测技术下的克隆性基因突变对第1次完全缓解（CR1）状态下接受高剂量化疗或自体造血干细胞移植（强化巩固治疗）的RUNX1-RUNX1T1融合基因阳性急性髓系白血病（AML）预后的影响。方法收集2011年7月至2017年8月在苏州大学附属第一医院CR1状态下接受强化巩固治疗的79例RUNX1-RUNX1T1融合基因阳性AML患者的临床资料，通过Kaplan-Meier曲线、Cox回归模型分析临床因素及突变基因对患者总生存（OS）和无病生存（DFS）时间的影响。结果在79例患者中，检出C-KIT、FLT3、CEBPA、DNMT3A基因突变者分别为25例（31.6％）、6例（7.6％）、8例（8.9％）、1例（1.3％），其中C-KIT exon17及C-KIT exon8突变分别为19例（24.1％）、5例（6.3％），FLT3-ITD突变为5例（6.3％）。初诊白细胞计数越高，患者的OS时间越短（P＝0.030），合并C-KIT exon17突变患者的OS时间（P＝0.010）和DFS时间（P＝0.006）明显缩短，合并FLT3-ITD基因突变患者的OS时间（P＝0.048）和DFS时间（P＝0.071）缩短。多因素分析显示合并C-KIT exon17和FLT3-ITD突变均为影响患者预后的独立因素。结论在接受强化巩固治疗的RUNX1-RUNX1T1融合基因阳性AML患者中，C-KIT exon17、FLT3-ITD基因突变提示预后较差，这将对细化患者危险度分层、个体化治疗、评估预后有指导意义。

Calcifying fibrous tumor: a clinicopathological analysis of 32 cases

Objective: To investigate the clinicopathological characteristics, histogenesis, immunophenotypes, molecular genetic characteristics, diagnosis and differential diagnosis of calcifying fibrous tumors (CFT). Methods: A total of 32 cases of CFT (22 cases from Henan Provincial People's Hospital and 10 cases from PLA Army Medical Center) diagnosed between June 2009 and February 2019 were reviewed. The clinical and pathologic data were analyzed. Results: There were 12 male and 20 female patients, aged from 15 to 63 years (mean 40.8 years). Eleven cases occurred in stomach, four cases in retroperitoneum, four cases in ovary, two cases in scrotum, two cases in mediastinum, two cases in head and neck, one case each in thoracic cavity, lung, adrenal gland, kidney, sigmoid colon, epididymis and mesosalpinx. All the tumors were solid masses with clear boundaries. The maximal dimension of the tumors ranged from 0.6 to 10.0 cm. Microscopically, there was hypocellular stromal sclerosis and wavy storiform coarse collagen with superimposed scattered or patchy lymphocytes and plasma cells; calcification or gravel formation were also detected. Immunohistochemistry showed that spindle cells were positive for vimentin and some were positive for CD34; and they were negative for calponin, SMA, desmin, S-100 protein, SOX10, STAT6, β-catenin, ALK, CD117, DOG1, CKpan, and EMA. No ALK rearrangement was detected by FISH in all cases. No C-KIT and PDGFRA mutation was detected in all the tested 11 cases of stomach, four cases of retroperitoneal and one case of sigmoid colon CFT. MDM2 was not amplified by FISH in all four tested cases of retroperitoneal CFT. Conclusions: CFT is a rare benign tumor of fibroblastic cell origin. The diagnosis mainly depends on histomorphologic analysis and immunophenotyping. CFT should be differentiated from other benign and malignant spindle cell mesenchymal tumors.

Analysis of RUNX1 Gene Mutation in Patients with Myelodysplastic Syndrome

To investigate the mutation of RUNX1 gene in patients with myelodysplastic syndrome (MDS) and its correlation with other gene mutations and some clinical parameters. The mutations of RUNX1, DNMT3A, TET2, IDH1/2, NPM1, FLT3-ITD and C-KIT in 170 patients with MDS were detected by direct and indirect sequencing of genomic DNA-PCR amplification products. The RUNX1 mutation was found in 23 patients (13.5 %, 23/170). Among the 170 patients, other most frequent mutation was TET2 (11.2%, 19/170), followed by mutations in DNMT3A (9.4%, 16/170), NPM1 (8.2%, 14/170), IDH2 (4.1%, 7/170)、FLT3-ITD (2.9%, 5/170), IDH1 (1.7%, 3/170) and c-KIT (0.58%, 1/170). The most common coexisting mutations were TET2 (5/23). The RUNX1-mutated group showed significantly higher leukocyte levels, higher percentages of blast cells, higher incidences of leukemia transformation and lower platelet counts in comparison with RUNX1 non-mutation group (P＜0.05). whereas there were no statistically significant difference in age, MDS subtype, karyotype and hemoglobin level between 2 groups (P＞0.05). Seventeen patients harboring RUNX1 mutations were followed up and almost 47.05% (8/17) of the patients progressed into acute myeloid leukemia (AML). The rates of transformation into AML in ASXL1-mutation group was significantly higher than that in ASXLL- non-mutation group (47.05% vs 11.7%) (P=0.001). The incidence of RUNX1 mutation is high in MDS patients. The RUNX1-mutated patients have higher leukocyte level, higher percentages of blast cells, higher incidences of leukemia transformation and lower platelet count.

Analysis of RUNX1 Gene Mutation in Patients with Myelodysplastic Syndrome

To investigate the mutation of RUNX1 gene in patients with myelodysplastic syndrome (MDS) and its correlation with other gene mutations and some clinical parameters. The mutations of RUNX1, DNMT3A, TET2, IDH1/2, NPM1, FLT3-ITD and C-KIT in 170 patients with MDS were detected by direct and indirect sequencing of genomic DNA-PCR amplification products. The RUNX1 mutation was found in 23 patients (13.5 %, 23/170). Among the 170 patients, other most frequent mutation was TET2 (11.2%, 19/170), followed by mutations in DNMT3A (9.4%, 16/170), NPM1 (8.2%, 14/170), IDH2 (4.1%, 7/170)、FLT3-ITD (2.9%, 5/170), IDH1 (1.7%, 3/170) and c-KIT (0.58%, 1/170). The most common coexisting mutations were TET2 (5/23). The RUNX1-mutated group showed significantly higher leukocyte levels, higher percentages of blast cells, higher incidences of leukemia transformation and lower platelet counts in comparison with RUNX1 non-mutation group (P＜0.05). whereas there were no statistically significant difference in age, MDS subtype, karyotype and hemoglobin level between 2 groups (P＞0.05). Seventeen patients harboring RUNX1 mutations were followed up and almost 47.05% (8/17) of the patients progressed into acute myeloid leukemia (AML). The rates of transformation into AML in ASXL1-mutation group was significantly higher than that in ASXLL- non-mutation group (47.05% vs 11.7%) (P=0.001). The incidence of RUNX1 mutation is high in MDS patients. The RUNX1-mutated patients have higher leukocyte level, higher percentages of blast cells, higher incidences of leukemia transformation and lower platelet count.

Relation of ASXL2 Gene Mutation with Clinical Characteristics, Prognosis and C-KIT Gene Mutation in AML Patients with AML1- ETO Fusion Gene

To analyze relation of ASXL2 gene mutation with the clinical characteristics, prognosis and C-KIT gene mutation in acute myeloid leukemia (AML) patients with AML1-ETO fusion gene. The clinical data of 63 primary AML patients with AML1-ETO fusion gene were collected and retrospectively analyzed. The mutation of ASXL2 gene was directly sequenced by PCR. The clinical characteristics, C-KIT mutation rate and prognosis were compared between the patients with ASXL2 gene mutation (group A) and non-mutation (group B). Among 63 patients, 8 (12.70%) cases of ASXL2 mutation gene was detected. Hemoglobin level in peripheral blood of patients in group A was significantly lower than that in group B (P＜0.01). There was no significant difference in sex, ages proportion of bone marrow blasts, lymph node enlargement, peripheral blood leukocytes count and platelets between the two groups (P＞0.05). The infiltration of central nervous system, liver and spleen was not found in both groups. The expression of CD33 in group A was significantly lower than that in group B (P＜0.05), but the results of other immunophenotype analysis were not significantly different between the two groups (P＞0.05). The remission rate and median survival time were not significantly different between two groups (P＞0.05). The detection rate of C-KIT gene mutation were not significantly different between group A and group B (P＞0.05). Among AML patients with AML1-ETO fusion gene, ASXL2 gene mutation accounts for a certain ratio, and the peripheral blood hemoglobin concentration and CD33 expression in these patients are often low. At the same time, ASXL2 gene mutation may not be closely related with C-KIT gene mutation.

Relation of ASXL2 Gene Mutation with Clinical Characteristics, Prognosis and C-KIT Gene Mutation in AML Patients with AML1- ETO Fusion Gene

To analyze relation of ASXL2 gene mutation with the clinical characteristics, prognosis and C-KIT gene mutation in acute myeloid leukemia (AML) patients with AML1-ETO fusion gene. The clinical data of 63 primary AML patients with AML1-ETO fusion gene were collected and retrospectively analyzed. The mutation of ASXL2 gene was directly sequenced by PCR. The clinical characteristics, C-KIT mutation rate and prognosis were compared between the patients with ASXL2 gene mutation (group A) and non-mutation (group B). Among 63 patients, 8 (12.70%) cases of ASXL2 mutation gene was detected. Hemoglobin level in peripheral blood of patients in group A was significantly lower than that in group B (P＜0.01). There was no significant difference in sex, ages proportion of bone marrow blasts, lymph node enlargement, peripheral blood leukocytes count and platelets between the two groups (P＞0.05). The infiltration of central nervous system, liver and spleen was not found in both groups. The expression of CD33 in group A was significantly lower than that in group B (P＜0.05), but the results of other immunophenotype analysis were not significantly different between the two groups (P＞0.05). The remission rate and median survival time were not significantly different between two groups (P＞0.05). The detection rate of C-KIT gene mutation were not significantly different between group A and group B (P＞0.05). Among AML patients with AML1-ETO fusion gene, ASXL2 gene mutation accounts for a certain ratio, and the peripheral blood hemoglobin concentration and CD33 expression in these patients are often low. At the same time, ASXL2 gene mutation may not be closely related with C-KIT gene mutation.

Gastrointestinal Stromal Tumors (GIST): an Overview

Gastrointestinal stromal tumors are rare mesenchymal tumors of the alimentary tract with varied clinical presentation ranging from small asymptomatic tumors detected incidentally to large palpable abdominal masses which may present with gastrointestinal bleeding, perforation, or obstruction. CT abdomen is the imaging modality of choice. Treatment depends upon the size, location and risk stratification. Complete surgical excision is the treatment of choice for resectable tumours. The discovery of c-kit mutations and tyrosine-kinase inhibitors has revolutionized the treatment of locally advanced, metastatic and recurrent tumors.

C-KIT mutation in thymic carcinomas.

Thymic epithelial tumours are rare malignancies oftheanterior superior mediastinum. Several studies have analysed thepresence ofc-KIT mutations in thymic carcinoma. Immunohistochemical c-KIT expression and mutations in exons 8, 9, 11, 13, 14, 17, and 18 of the KIT gene and in the promoter region of the TERT gene (chr5, 1,295,228C>T/A and 1,295,250C>T) were analysed by PCR based direct sequencing using representative formalin-fixed paraffin-embedded tumour samples of 18 thymic carcinomas. Of 18 patients, 4 test samples were excluded from thestudy due to inadequate DNA quality. Of 14 patients with thymic carcinomas, KIT and TERT mutation was not detected in any samples. C-KIT expression was associated with nearly aworse overall survival (median time 24.160-49.840, log-rank, p=0.05). We showed that squamous cell carcinomas led to worse survival than other subtypes. As expected, TNM stage II was significantly correlated with better OS (p = 0.015). Thymic carcinoma is characterised by aKIT-positive and CD5-positive staining pattern. We report aworse overall survival for patients with c-kit expressing tumours. These data suggest anegative prognostic role for c-kit expression especially within thefirst 5 years.

A RETROSPECTIVE STUDY OF CANINE CUTANEOUS MAST CELL TUMOR: CORRELATION BETWEEN CLINICAL, HISTOLOGICAL AND MOLECULAR CHARACTERISTICS/ UM ESTUDO RETROSPECTIVO DE MASTÓCITOS CUTÂNEOS CANINOS: CORRELAÇÃO ENTRE CARACTERÍSTICAS CLÍNICAS, HISTOLÓGICAS E MOLECULARES

Mast cell tumor (MCT), or mastocytoma, the second most common skin tumor in dogs, is characterized by neoplastic transformations and abnormal proliferation of mast cells from cutaneous or visceral origins. Mutations in the proto-oncogene c-kit are present in 15% of dogs with MCT and up to 35% in high-grade tumors. In the clinical management of the disease, some characteristics, such as anatomical occurrence, histological grading, clinical staging, age and breed, are important parameters to better drive the treatment and predict the prognosis of each patient. However, it is not clear the correlations between c-kit mutation and clinical/epidemiological data, demonstrating the necessity of new studies. In this study, 78 clinical cases of canine patients with MCT were analyzed in Campinas - SP, Brazil, at Oncovida - Veterinary Oncology Center, in the period of 2017 to 2019, to determine the frequency, prevalence and correlations between molecular, clinical and epidemiological aspects. Results presented here shows that mixed breed dogs (51%) were the most affected, followed by Labrador (17%) and Boxer (16%). Most dogs were female (67%), aged 6 to 10 years (62%); 42% of the animals had tumors located in the pelvic limb and 17% had nodules in the chest. The most used method for diagnosis was histopathology, totalizing 60% of cases, followed by aspirative cytology (26%) and immunohistochemistry (8%). Regarding histological variables, 3 patients had grade I (11.8%), 47 had grade II (61%) and 15 had grade III (19%) and, according to KIUPEL et al. (2011) classification, 77 % of the cases presented low grade and 23% were high grade. The survival of these patients was also analyzed, demonstrating that animals presenting grade I and grade II (low grade) had longer survival (68%) in relation to grade III (high grade) (16%) The variables showed a significant correlation between histological grade and c-kit mutation with breed, age, localization of the tumor, diagnostic, chosen treatment and survival, indicating that they are both decisive to the outcome of the disease. Only sex was not correlated, suggesting that both the grade of the tumor and the c-kit mutation were not found to contribute to a different development of the tumor in male or female. These results demonstrate important data on the clinical behavior of MCT in the region of Campinas-SP, presenting relevant knowledge that can be used in the future in the clinical manage of the patients with this disease and demonstrating the necessity of further studies on the epidemiology of MCT in each region of Brazil.

KIT and Melanoma: Biological Insights and Clinical Implications.

Melanoma, originating from epidermal melanocytes, is a heterogeneous disease that has the highest mortality rate among all types of skin cancers. Numerous studies have revealed the cause of this cancer as related to various somatic driver mutations, including alterations in KIT—a proto-oncogene encoding for a transmembrane receptor tyrosine kinase. Although accounting for only 3% of all melanomas, mutations in c-KIT are mostly derived from acral, mucosal, and chronically sun-damaged melanomas. As an important factor for cell differentiation, proliferation, and survival, inhibition of c-KIT has been exploited for clinical trials in advanced melanoma. Here, apart from the molecular background of c-KIT and its cellular functions, we will review the wide distribution of alterations in KIT with a catalogue of more than 40 mutations reported in various articles and case studies. Additionally, we will summarize the association of KIT mutations with clinicopathologic features (age, sex, melanoma subtypes, anatomic location, etc.), and the differences of mutation rate among subgroups. Finally, several therapeutic trials of c-KIT inhibitors, including imatinib, dasatinib, nilotinib, and sunitinib, will be analyzed for their success rates and limitations in advanced melanoma treatment. These not only emphasize c-KIT as an attractive target for personalized melanoma therapy but also propose the requirement for additional investigational studies to develop novel therapeutic trials co-targeting c-KIT and other cytokines such as members of signaling pathways and immune systems.

Programmed Death-ligand 1 (PD-L1) Expression in Thymic Epithelial Tumors.

Thymic epithelial tumors (TETs) are uncommon neoplasms of the mediastinum. The gold standard treatment is complete surgical resection which can be followed by radio/chemotherapy in selected cases. Targeted tyrosine kinase inhibition can be considered in only a limited number of aggressive or metastatic tumors as EGFR, BRAF, or c-kit mutations are rare. However, previous studies have demonstrated the efficacy of immune checkpoint inhibitors in epithelial neoplasias, such as in programmed cell death ligand 1 (PD-L1) expressing nonsmall cell lung carcinoma. Because of their rare occurrence the data on PD-L1 distribution in thymic neoplasias are limited. PD-L1 and PD-1 expression in tumor cells and tumor infiltrating immune cells was determined in TETs according to criteria published for lung carcinomas. Comparison with major clinical, pathologic, and biological features was also done. In total, 36 TETs (29 thymomas and 7 thymic carcinomas) were analyzed. PD-L1 immunohistochemical staining (Ventana PD-L1 clone SP142) was performed in all cases. The percentage of the positive tumor cells (TC value), the percentage of tumor area occupied by positive immune cells (IC value) was evaluated. Evaluation of PD-L1 expression in tumor cells showed a good reproducibility (κ-value: 0.840; Spearman r=0.966; P<0.0001). About 69% of thymomas (20/29) and 43% of thymic carcinomas (3/7) showed high positivity rate (TC≥50% or IC ≥10%), which may indicate therapeutic advantage similar to nonsmall cell lung cancers defined by the same conditions. PD-L1 expression is common in different epithelial tumors of the thymus, which suggests the potential effectiveness of drugs targeting the PD-1/PD-L1 interactions in these neoplasms.

Interstitial cells of Cajal in Wsh/Wsh c-kit mutant mice.

The c-Kit receptor tyrosine kinase regulates the development and differentiation of several progenitor cells. In the gastrointestinal (GI) tract, the c-Kit regulates the development of the interstitial cells of Cajal (ICC) that are responsible for motility regulation of the GI musculature. W-sash (Wsh) is an inversion mutation upstream of the c-kit promoter region that affects a key regulatory element, resulting in cell-type-specific altered gene expression, leading to a decrease in the number of mast cells, melanocytes, and ICC. We extensively examined the GI tract of Wsh/Wsh mice using immunohistochemistry and electron microscopy. Although the musculature of the Wsh/Wsh mice did not show any c-Kit immunoreactivity, we detected intensive immunoreactivity for transmembrane member 16A (TMEM16A, anoctamin-1), another ICC marker. TMEM16A immunopositive cells were observed as ICC-MY in the gastric corpus-antrum and the large intestine, ICC-DMP in the small intestine, and ICC-SM in the colon. Electron microscopic analysis revealed these cells as ICC from their ultrastructural features, such as numerous mitochondria and caveolae, and their close contact with nerve terminals. In the developmental period, we examined 14.5 and 18.5 day embryos but did not observe c-Kit immunoreactivity in the Wsh/Wsh small intestine. From this study, ICC subtypes developed and maturated structurally without c-Kit expression. Wsh/Wsh mice are a new model to investigate the effects of c-Kit and unknown signaling on ICC development and function.