Tumor-related gene expression levels in thymic carcinoma and Type B3 thymoma

ACTN4 is associated with the malignant potential of thymic epithelial tumors through the β-catenin/Slug pathway

Thymic epithelial tumors (TETs) are rare tumors arising from the mediastinum. Among TETs, thymoma type B2, B3 and thymic carcinoma are highly malignant and often present invasion and dissemination. However, the biological characteristics of TETs have not been thoroughly studied, and their mechanisms of invasion and dissemination are largely unknown. α-Actinin 4 (ACTN4) is a member of actin-binding proteins and reportedly plays important roles in the progression of several cancers. In this study, we investigated the relationship between ACTN4 and characteristics of the malignant potential of TETs, such as invasion and dissemination. In vitro experiments using Ty-82 thymic carcinoma cells revealed that overexpression of ACTN4 enhanced the proliferative and invasive ability of Ty-82 cells; conversely, knockdown of ACTN4 attenuated the proliferative and invasive potential of Ty-82 cells. In western blotting (WB) experiments, ACTN4 induced the phosphorylation of extracellular signal-regulated kinase and glycogen synthase kinase 3β to regulate the β-catenin/Slug pathway. Furthermore, WB analysis of cancer tissue-origin spheroids from patients with TETs showed results similar to those for Ty-82 cells. In vivo experiments showed that the knockdown of ACTN4 significantly suppressed the dissemination of Ty-82 cells. A WB and immunohistochemistry staining comparison of primary and disseminated lesions of TETs using surgical specimens showed upregulated expression of ACTN4, β-catenin, and Slug proteins in disseminated lesions. In summary, our study suggests ACTN4 is associated with malignant potential characteristics such as invasion and dissemination in TETs via the β-catenin/Slug pathway.

Long-term follow-up and exploratory analysis of lenvatinib in patients with metastatic or recurrent thymic carcinoma: Results from the multicenter, phase 2 REMORA trial

OBJECTIVES

The main objective of this report was to detail the long-term follow-up data from the REMORA study, which investigated the safety and efficacy of lenvatinib in patients with thymic carcinoma. In addition, an exploratory analysis of the association between relative dose intensity (RDI) and the efficacy of lenvatinib is presented.

MATERIALS AND METHODS

The single-arm, open-label, phase 2 REMORA study was conducted at eight Japanese institutions. Forty-two patients received oral lenvatinib 24 mg once daily in 4-week cycles until the occurrence of intolerable adverse events or disease progression. The REMORA long-term follow-up data were evaluated, including overall survival (OS). RDI was calculated by dividing the actual dose administered to the patient by the standard recommended dose. This trial is registered on JMACCT (JMA-IIA00285) and on UMIN-CTR (UMIN000026777).

RESULTS

The updated median OS was 28.3 months (95 % confidence interval [CI]: 17.1-34.0 months), and the OS rate at 36 months was 35.7 % (95 % CI: 21.7 %-49.9 %). When grouped by RDI of lenvatinib, the median OS was 38.5 months (95 % CI: 31.2-not estimable) in patients with ≥ 75 % RDI and 17.3 months (95 % CI: 13.4-26.2 months) in patients with < 75 % RDI (hazard ratio 0.46 [95 % CI: 0.22-0.98]; P = 0.0406) at 8 weeks. Patients who maintained their lenvatinib dose over 8 weeks had a higher objective response rate than patients whose doses were reduced (75.0 % vs 29.4 %; P = 0.0379). No new safety concerns or treatment-related deaths were reported, and lenvatinib had a tolerable safety profile.

CONCLUSION

This follow-up report updated OS in patients with metastatic or recurrent thymic carcinoma. A higher RDI of lenvatinib at 8 weeks could be associated with improved outcomes.

Molecular and Functional Key Features and Oncogenic Drivers in Thymic Carcinomas

Thymic epithelial tumors, comprising thymic carcinomas and thymomas, are rare neoplasms. They differ in histology, prognosis, and association with autoimmune diseases such as myasthenia gravis. Thymomas, but not thymic carcinomas, often harbor GTF2I mutations. Mutations of CDKN2A, TP53, and CDKN2B are the most common thymic carcinomas. The acquisition of mutations in genes that control chromatin modifications and epigenetic regulation occurs in the advanced stages of thymic carcinomas. Anti-angiogenic drugs and immune checkpoint inhibitors targeting the PD-1/PD-L1 axis have shown promising results for the treatment of unresectable tumors. Since thymic carcinomas are frankly aggressive tumors, this report presents insights into their oncogenic drivers, categorized under the established hallmarks of cancer.

[Analysis of Gene Variation in Thymoma by Microarray]

BACKGROUND

Thymoma is the most common malignant tumor in anterior mediastinum, and its specific pathogenesis is still unclear. This limits the study of targeted drugs for thymoma. The aim of the study is to investigate the genes and signal pathways of thymoma, and provide help for the research of thymic tumor pathogenesis using the technology of second-generation genechip to analyze thymoma.

METHODS

From January 2015 to December 2017, we analyzed 31 cases of thymoma by CapitaBio mRNA expression profile genechip technology, and then confirmed the genes by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

We found some genes with different expression levels between thymoma and surrounding thymus tissue. Among them, six driving genes (FANCI, CAPD3, NCAPG, OXCT1, EPHA1 and MCM2) were significantly abnormal in thymoma. Some specific genes affected by copy-number variation were detected: E2F2, EphA1, CCL25 and MCM2 were significantly up-regulated, while IL-6, CD36, FABP4, SH2D1A and MYOC genes were significantly down-regulated. KEGG database analysis showed that the expression of 10 signaling pathway genes was generally up-regulated or down-regulated, such as systemic lupus erythematosus, viral oncogenes, primary immunodeficiency, cell cycle genes and p53 signaling pathway, which may be related to occurrence of thymoma.

CONCLUSIONS

We found a variety of genes abnormally expressed in thymoma, which will provide reference for the study of pathogenesis and biomarkers of thymoma in the future.

Pathology of thymoma-where are we today?

Thymoma is the commonest epithelial neoplasm arising from thymus gland. Tumour is slow growing and in the absence of metastasis, surgery is the treatment of choice. Complete resection and bland morphology are important prognostic features. However, a significant proportion of these tumours tend to recur. These recurrent tumours, advanced thymomas and thymic carcinomas require platinum-based combination chemotherapy and radiotherapy. Efforts are being made to explore additional treatment modalities to control disease with the aim of improving survival. Number of thymoma cases worldwide is small in comparison to lung cancers. As a result, fewer studies have been carried out to enhance our understanding of molecular events responsible for the initiation, maintenance, and progression of thymomas. Inspite of this there are advances in understanding the pathology of thymic epithelial neoplasms including genetics, PD-L1 and molecular testing which has bearing on the prognosis, post-surgical management, and testing algorithm. Similar to pulmonary pathology, thymic epithelial tumours will require adequate tumour sampling to carry out ancillary testing. Mutational analytical tests include EGFR, RAS, BRAF, RET, AKT1, PIK3CA and T53 genes. If adequate sample is available (upto100 cells), PD-L1 testing should be considered for immunotherapy in recurrent/ advanced thymomas and thymic carcinomas. This list is likely to expand in future with increasing emphasis on molecular testing to support treatment with newer therapies.

[Treatment of Recurrent Thymoma]

胸腺瘤是一种具有恶性潜能的疾病，完整切除后的复发率为10%-30%。复发性胸腺瘤的治疗策略及标准未达成一致，治疗方式包括再次手术治疗、化疗、放疗、靶向治疗及免疫治疗等，至今存在着争议。在这篇综述中，通过回顾既往的文献，总结了复发性胸腺瘤的不同治疗方法的适应证、疗效以及预后，以期给复发性胸腺瘤治疗标准的制定提供一些参考。

A novel intraperitoneal therapy for gastric cancer with DFP-10825, a unique RNAi therapeutic targeting thymidylate synthase, in a peritoneally disseminated xenograft model

Purpose

In advanced gastric cancer, peritoneal dissemination is a life‐threatening mode of metastasis. Since the treatment options with conventional chemotherapy remain limited, any novel therapeutic strategy that could control such metastasis would improve the outcome of treatment. We recently developed a unique RNA interference therapeutic regimen (DFP‐10825) consisting of short hairpin RNA against thymidylate synthase (TS shRNA) and cationic liposomes. The treatment with DFP‐10825 has shown remarkable antitumor activity in peritoneally disseminated human ovarian cancer–bearing mice via intraperitoneal administration. In this study, we expanded DFP‐10825 to the treatment of peritoneally disseminated gastric cancer.

Methods

DFP‐10825 was administered intraperitoneally into mice with intraperitoneally implanted human gastric cancer cells (MKN45 or NCI‐N87). Antitumor activity and host survival benefits were monitored. Intraperitoneal distribution of fluorescence‐labeled DFP‐10825 was monitored in this MKN45 peritoneally disseminated mouse model.

Results

Intraperitoneal injection of DFP‐10825 suppressed tumor growth in two peritoneally disseminated cancer models (MKN45 and NCI‐N87) and increased the survival time of the MKN45 model without severe side effects. Throughout the treatment regimen, no significant body weight loss was associated with the administration of DFP‐10825. Interestingly, after intraperitoneal injection, fluorescence‐labeled DFP‐10825 retained for more than 72 hours in the peritoneal cavity and selectively accumulated in disseminated tumors.

Conclusions

Intraperitoneal injection of DFP‐10825 demonstrated effective antitumor activity without systemic severe adverse effects via the selective delivery of RNAi molecules into disseminated tumors in the peritoneal cavity. Our current study indicates that DFP‐10825 could become an alternative option to improve the outcomes of patients with peritoneally disseminated gastric cancer.

GTF2I mutation frequently occurs in more indolent thymic epithelial tumors and predicts better prognosis

OBJECTIVES

A missense mutation in GTF2I was previously identified in thymic epithelioid tumor (TET). However, the clinicopathological relevance of GTF2I mutation has not been illustrated. We studied the prognostic importance of GTF2I mutation as well as its relation to histological subtypes in a large number of TETs.

METHODS

TET samples from 296 patients with clinical and follow-up data were collected, and histological subtypes were classified. Analysis of the GTF2I (chromosome 7 c.74146970T>A) mutation was undertaken by using quantitative real time polymerase chain reaction (qPCR) and direct sequencing. The association of GTF2I mutation with clinicopathological features as well as prognosis was analyzed.

RESULTS

One hundred twenty-four out of 296 (41.9%) patients harbored the GTF2I mutation (chromosome 7 c.74146970T>A). GTF2I mutation was observed in 20 (87.0%) cases of type A thymoma, 70 (78.7%) of type AB thymoma, and the frequency decreased with the degree of histological subtype aggressiveness, with the lowest rate in thymic carcinoma (7.7%). The difference of GTF2I mutation distribution in histological subtypes was statistically significant (p<0.001). The GTF2I mutation was found more frequently in patients with early Masaoka stage (I-II, n=112, 90.3%) than in those with advanced stage (III-IV) disease (n=12, 9.6%, p<0.001). However, only histological subtype significantly predicted the presence of the GTF2I mutation in patients with TETs. The presence of the GTF2I mutation correlated with better prognosis (90.0% compared to 72.0% 5-year survival, and 86% compared to 56% 10-year survival, respectively; log-rank p=0.001). Moreover, it was an independent prognostic factor [hazard ratio (HR), 0.35; 95% confidential interval (CI), 0.15-0.81; p=0.014)].

CONCLUSIONS

The frequency of the GTF2I mutation is higher in more indolent TETs, and correlates with better prognosis. Further studies are required to elucidate the role of the GTF2I mutation in TETs and its clinical application.