Establishment and characterization of esophageal squamous cell carcinoma patient-derived xenograft mouse models for preclinical drug discovery

Understanding PI3K/Akt/mTOR signaling in squamous cell carcinoma: mutated PIK3CA as an example

Compared with those in adenocarcinoma, PIK3CA mutations are more common in squamous cell carcinoma (SCC), which arises from stratified squamous epithelia that are usually exposed to adverse environmental factors. Although hotspot mutations in exons 9 and 20 of PIK3CA, including E542K, E545K, H1047L and H1047R, are frequently encountered in the clinic, their clinicopathological meaning remains to be determined in the context of SCC. Considering that few reviews on PIK3CA mutations in SCC are available in the literature, we undertook this review to shed light on the clinical significance of PIK3CA mutations, mainly regarding the implications and ramifications of PIK3CA mutations in malignant cell behavior, prognosis, relapse or recurrence and chemo- or radioresistance of SCC. It should be noted that only those studies regarding SCC in which PIK3CA was mutated were cherry-picked, which fell within the scope of this review. However, the role of mutated PIK3CA in adenocarcinoma has not been discussed. In addition, mutations occurring in other main members of the PI3K-AKT-mTOR signaling pathway other than PIK3CA were also excluded.

Promising preclinical patient-derived organoid (PDO) and xenograft (PDX) models in upper gastrointestinal cancers: progress and challenges

Gastrointestinal (GI) cancers (gastric cancer, oesophageal cancer, liver cancer, colorectal cancer, etc.) are the most common cancers with the highest morbidity and mortality in the world. The therapy for most GI cancers is difficult and is associated with a poor prognosis. In China, upper GI cancers, mainly gastric cancer (GC) and oesophageal cancer (EC), are very common due to Chinese people's characteristics, and more than half of patients are diagnosed with distant metastatic or locally advanced disease. Compared to other solid cancers, such as lung cancer and breast cancer, personalized therapies, especially targeted therapy and immunotherapy, in GC and EC are relatively lacking, leading to poor prognosis. For a long time, most studies were carried out by using in vitro cancer cell lines or in vivo cell line-derived xenograft models, which are unable to reproduce the characteristics of tumours derived from patients, leading to the possible misguidance of subsequent clinical validation. The patient-derived models represented by patient-derived organoid (PDO) and xenograft (PDX) models, known for their high preservation of patient tumour features, have emerged as a very popular platform that has been widely used in numerous studies, especially in the research and development of antitumour drugs and personalized medicine. Herein, based on some of the available published literature, we review the research and application status of PDO and PDX models in GC and EC, as well as detail their future challenges and prospects, to promote their use in basic and translational studies or personalized therapy.

Ivermectin induces apoptosis of esophageal squamous cell carcinoma via mitochondrial pathway

Background

Esophageal squamous cell carcinoma (ESCC) is the most predominant primary malignant tumor among worldwide, especially in China. To date, the successful treatment remains a mainly clinical challenge, it is imperative to develop successful therapeutic agents.

Methods

The anti-proliferative effect of ivermectin on ESCC is investigated in cell model and in nude mice model. Cell apoptosis was assessed using flow cytometry, TUNEL assay and western blotting. Mitochondrial dysfunction was determined by reactive oxygen species accumulation, mitochondrial membrane potential and ATP levels.

Results

Our results determined that ivermectin significantly inhibited the proliferation of ESCC cells in vitro and in vivo. Furthermore, we found that ivermectin markedly mediated mitochondrial dysfunction and induced apoptosis of ESCC cells, which indicated the anti-proliferative effect of ivermectin on ESCC cells was implicated in mitochondrial apoptotic pathway. Mechanistically, ivermectin significantly triggered ROS accumulation and inhibited the activation of NF-κB signaling pathway and increased the ratio of Bax/Bcl-2.

Conclusions

These finding indicated that ivermectin has significant anti-tumour potential for ESSC and may be a potential therapeutic candidate against ESCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-09021-x.

Advances and challenges in the treatment of esophageal cancer

Esophageal cancer (EC) is one of the most common cancers with high morbidity and mortality rates. EC includes two histological subtypes, namely esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC). ESCC primarily occurs in East Asia, whereas EAC occurs in Western countries. The currently available treatment strategies for EC include surgery, chemotherapy, radiation therapy, molecular targeted therapy, and combinations thereof. However, the prognosis remains poor, and the overall five-year survival rate is very low. Therefore, achieving the goal of effective treatment remains challenging. In this review, we discuss the latest developments in chemotherapy and molecular targeted therapy for EC, and comprehensively analyze the application prospects and existing problems of immunotherapy. Collectively, this review aims to provide a better understanding of the currently available drugs through in-depth analysis, promote the development of new therapeutic agents, and eventually improve the treatment outcomes of patients with EC.

CDK4 Amplification in Esophageal Squamous Cell Carcinoma Associated With Better Patient Outcome

In the present study, we aimed to investigate the clinical and prognostic values of CDK4 amplification and improve the risk stratification in patients with esophageal squamous cell carcinoma. CDK4 amplification was analyzed by fluorescence in situ hybridization using tissue microarray consisting of representative tissues of 520 patients with esophageal squamous cell carcinoma, and its correlation with clinicopathological features and clinical outcomes were evaluated. CDK4 amplification was found in 8.5% (44/520) of patients with esophageal squamous cell carcinoma. CDK4 amplification was negatively correlated with disease progression (P = 0.003) and death (P = 0.006). Patients with CDK4 amplification showed a significantly better disease-free survival (P = 0.016) and overall survival (P = 0.023) compared with those patients without CDK4 amplification. When patients were further stratified into I–II stage groups and III–IV stage groups, CDK4 amplification was significantly associated with both better disease-free survival (P = 0.023) and overall survival (P = 0.025) in the I–II stage group rather than the III–IV stage group. On univariate and multivariate analysis, invasive depth and CDK4 amplification were associated with disease-free survival and overall survival. Taken together, CDK4 amplification was identified as an independent prognostic factor for survival, which could be incorporated into the tumor–node–metastasis staging system to refine risk stratification of patients with esophageal squamous cell carcinoma.

Patient-derived xenograft: a developing tool for screening biomarkers and potential therapeutic targets for human esophageal cancers

Esophageal cancer (EC) represents a human malignancy, diagnosed often at the advanced stage of cancer and resulting in high morbidity and mortality. The development of precision medicine allows for the identification of more personalized therapeutic strategies to improve cancer treatment. By implanting primary cancer tissues into immunodeficient mice for expansion, patient-derived xenograft (PDX) models largely maintain similar histological and genetic representations naturally found in patients' tumor cells. PDX models of EC (EC-PDX) provide fine platforms to investigate the tumor microenvironment, tumor genomic heterogeneity, and tumor response to chemoradiotherapy, which are necessary for new drug discovery to combat EC in addition to optimization of current therapeutic strategies for EC. In this review, we summarize the methods used for establishing EC-PDX models and investigate the utilities of EC-PDX in screening predictive biomarkers and potential therapeutic targets. The challenge of this promising research tool is also discussed.

Selected updates in molecular and genomic pathology of esophageal cancer

Recent years have seen rapid advances in the field of molecular and genomic pathology that have not only improved understanding of esophageal carcinogenesis and tumor immune environment in general but also have reshaped pathology practice and clinical management. In this article, we provide updates on three topics (1) human epidermal growth factor receptor 2, the first and most important biomarker in targeted therapy of esophageal cancer; (2) programmed death 1/programmed death ligand 1, recent biomarkers that have shown promise in treating both esophageal adenocarcinoma and esophageal squamous cell carcinoma; and (3) human papillomavirus involvement in esophageal carcinogenesis, one of the most debated topics in the field, discussed here with a renewed understanding from recent genomic and molecular data.

Proteomic Analysis of Human Esophageal Cancer Using Tandem Mass Tag Quantifications

Esophageal cancer (EC) is a type of extremely aggressive gastrointestinal cancer with high incidences in China and other Asian countries. EC does not have specific symptoms and is relatively easy to metastasize, which makes it difficult in early diagnosis. Thus, novel noninvasive diagnostic method is urgently needed in clinical practice. In this study, mass spectrometry with tandem mass tags and differential protein analysis were applied for identifying esophageal cancer-related proteins. The identified proteins were annotated based on their enrichment in Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. In addition, hierarchical clustering was applied based on differentially expressed proteins. As a result, a total of 5131 quantifiable proteins were identified from our liquid chromatography-tandem mass spectrometry with tandem mass tags (LC-MS/MS-TMT) method with 63 upregulated and 97 downregulated differential proteins between esophageal cancer and controlled normal samples. The differentially expressed proteins were highly enriched in GO terms associated with mitochondrial dissemble and apoptosis, and blood vessel regulation, and the upregulated differentially expressed proteins in EC samples were significantly enriched in major histocompatibility complex MHC-class I/II pathway of immune system. The functional clustering analysis revealed potential protein-protein interactions among tetraspanin, myosin, and S-100. In summary, our study provided a practical technological procedure of proteomic analysis for discovering novel biomarkers of a specific cancer type.

Identification of predictors of drug sensitivity using patient-derived models of esophageal squamous cell carcinoma

Previous studies from the Cancer Cell Line Encyclopedia (CCLE) project have adopted commercial pan-cancer cell line models to identify drug sensitivity biomarkers. However, drug sensitivity biomarkers in esophageal squamous cell carcinoma (ESCC) have not been widely explored. Here, eight patient-derived cell lines (PDCs) are successfully established from 123 patients with ESCC. The mutation profiling of PDCs can partially recapture the tumor tissue actionable mutations from 161 patients with ESCC. Based on these mutations and relative pathways in eight PDCs, 46 targeted drugs are selected for screening. Interestingly, some drug and biomarker relationships are established that were not discovered in the CCLE project. For example, CDKN2A or CDKN2B loss is significantly associated with the sensitivity of CDK4/6 inhibitors. Furthermore, both PDC xenografts and patient-derived xenografts confirm CDKN2A/2B loss as a biomarker predictive of CDK4/6 inhibitor sensitivity. Collectively, patient-derived models could predict targeted drug sensitivity associated with actionable mutations in ESCC.

Predicting the drug response of patients with cancer is crucial for implementing targeted therapy. Here, Su et al. make patient-derived cell lines and perform targeted sequencing and RNA-seq to identify CDKN2A/2B loss as a predictor of response to CDK4/6 inhibitors in esophageal squamous cell carcinoma.

Multiple modulatory activities of Andrographis paniculata on immune responses and xenograft growth in esophageal cancer preclinical models

BACKGROUND

Esophageal cancer (EC) is a malignant gastrointestinal cancer with high morbidity worldwide and is the fourth leading cause of cancer-related deaths in China. Even though surgery and/or chemotherapy/chemoradiation might achieve good therapeutic response, recurrence rate is high due to cancer metastasis. Hence, the use of alternative adjuvant treatments, such as herbal medicines, for metastatic EC remains a great desire of the patients. Our previous studies have demonstrated the anti-metastatic efficacy of hot water extract of Andrographis paniculata (APW) in human esophageal cancer cells and tumor-bearing nude mice.

PURPOSE

In the present study, the immunomodulatory activities of APW were further evaluated in human peripheral blood mononuclear cells (PBMCs) and in a carcinogen-induced esophageal tumorigenesis model using immune-competent C57BL/6 mice. Besides, the inhibitory effects of APW on esophageal cancer cell line-based xenografts and patient-derived xenografts (PDX) were examined so as to illustrate the potential multi-targeted efficacies of APW in esophageal cancer in pre-clinical models.

RESULTS

In vitro results showed that APW could stimulate proliferation of PBMCs, as well as TNF-α and IFN-γproductions. In mice with 4-nitroquinoline 1-oxide-induced tumorigenesis, 21-day oral treatment with APW (1600 mg/kg) decreased the level of dysplasia in esophagus and significantly modulated the population of regulatory T cells. The cytokines productions by spleen lymphocytes of APW-treated mice were shifted towards normal resting state (i.e. unchallenged with carcinogen). Furthermore, APW treatment suppressed the growth of cell line-based xenografts by significantly increasing apoptosis in tumors, without causing severe body weight loss as chemotherapeutics did. Most importantly, the inhibitory effects of APW treatment on esophageal patient-derived xenografts growth were demonstrated for the first time. Besides, several diterpenes were detected in the plasma after oral administration of APW in mice, suggesting that multi-components of APW were bioavailable and might have contributed towards the varied pharmacological activities demonstrated in our studies.

CONCLUSION

APW was shown to possess anti-tumor, anti-metastatic and immunomodulatory activities in esophageal cancer cell-based and animal models, including immunocompromised mice model and clinically relevant PDX model. Our findings illustrated the potential multi-targeted efficacies of APW in esophageal cancer management.

Establishment and characterization of melanoma patient-derived xenograft models for preclinical evaluation of novel therapeutics

Patient-derived xenograft (PDX) models mostly retain the histological and genetic features of their donor tumors, which have been used for investigating various types of cancer. However, PDX models for melanoma, especially acral melanoma, are reported occasionally. We aimed to establish a large panel of melanoma PDX models representing the predominant Asian melanomas. Ninety-three fresh melanoma samples were implanted subcutaneously into nonobese diabetic/severe combined immunodeficiency mice. The histological and genetic characteristics were analyzed in both patient tumors and PDX models using immunohistochemistry, PCR amplification, and Sanger sequencing. Furthermore, the sensitivities of PDX models harboring distinct mutation profiles to binimetinib (a MEK inhibitor), vemubrafenib (a BRAF inhibitor), and imatinib (a KIT inhibitor) were also evaluated. Twenty-five PDX models were established successfully [25/93 (26.9%)] and passaged to maintain tumors in vivo. Clinical stage and origin of tumor sample were correlated with successful establishment rates (P=0.008 and <0.001, respectively). The histological (expression of NRAS, P16, and RB) and genetic (mutation status of NRAS, BRAF, and KIT) characteristics were stably maintained from patient tumors to PDX models. Targeted drugs could inhibit the tumor growth of PDX models harboring the corresponding target gene mutations. These PDX models constitute a pharmacological platform, enabling personalized development of therapeutic strategies for Asian melanomas.

The anthelmintic drug flubendazole induces cell apoptosis and inhibits NF-κB signaling in esophageal squamous cell carcinoma

BACKGROUND AND OBJECTIVES

The nuclear factor kappa B (NF-κB) signaling is activated in esophageal squamous cell carcinoma (ESCC) and can be used as a potential target for anti-ESCC drug discovery. In this study, we aimed to investigate the function of flubendazole as a novel NF-κB inhibitor in ESCC cells.

MATERIALS AND METHODS

Cell Counting Kit-8 assay was carried out to assess cell viability of ESCC cells. Flow cytometry and immunoblotting were performed to examine cell apoptosis. Immunoblotting assay was used to analyze the protein expression of NF-κB signaling. Luciferase assay was performed to explore the activation of NF-κB. Plasmids were transfected into ESCC cells using Lipofectamine® 2000.

RESULTS

In this study, the anthelmintic drug flubendazole was found to inhibit the activation of IκBα kinases (IKKs), block the activation of IκBα, and decrease the phosphorylation of NF-κB p65, which could be a novel NF-κB inhibitor in ESCC cells. We also found that flubendazole inhibited the cell survival of different ESCC cells and induced cell apoptosis in both EC9706 and TE1 cells. Moreover, overexpression of constitutively activated IKKβ markedly decreased the cytotoxic effect of flubendazole on EC9706 and TE1 cells. In addition, flubendazole also showed a synergistic effect on ESCC cells when combined with doxorubicin.

CONCLUSION

The results above demonstrated that flubendazole showed its anti-tumor action by suppressing the NF-κB signaling pathway and suggested that flubendazole might be re-purposed for anti-ESCC therapy in clinic as a single agent or in combination with other anti-tumor drugs.

Tumor xenograft animal models for esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is the predominant subtype of esophageal cancer worldwide and highly prevalent in less developed regions. Management of ESCC is challenging and involves multimodal treatments. Patient prognosis is generally poor especially for those diagnosed in advanced disease stage. One factor contributing to this clinical dismal is the incomplete understanding of disease mechanism, for which this situation is further compounded by the presence of other limiting factors for disease diagnosis, patient prognosis and treatments. Tumor xenograft animal models including subcutaneous tumor xenograft model, orthotopic tumor xenograft model and patient-derived tumor xenograft model are vital tools for ESCC research. Establishment of tumor xenograft models involves the implantation of human ESCC cells/xenografts/tissues into immunodeficient animals, in which mice are most commonly used. Different tumor xenograft models have their own advantages and limitations, and these features serve as key factors to determine the use of these models at different stages of research. Apart from their routine use on basic research to understand disease mechanism of ESCC, tumor xenograft models are actively employed for undertaking preclinical drug screening project and biomedical imaging research.

PIK3CA mutation is a favorable prognostic factor in esophageal cancer: molecular profile by next-generation sequencing using surgically resected formalin-fixed, paraffin-embedded tissue

Background

Practical and reliable genotyping procedures with a considerable number of samples are required not only for risk-adapted therapeutic strategies, but also for stratifying patients into future clinical trials for molecular-targeting drugs. Recent advances in mutation testing, including next-generation sequencing, have led to the increased use of formalin-fixed paraffin-embedded tissue. We evaluated gene alteration profiles of cancer-related genes in esophageal cancer patients and correlated them with clinicopathological features, such as smoking status and survival outcomes.

Methods

Surgically resected formalin-fixed, paraffin-embedded tissue was collected from 135 consecutive patients with esophageal cancer who underwent esophagectomy. Based on the assessment of DNA quality with a quantitative PCR-based assay, uracil DNA glycosylase pretreatment was performed to ensure quality and accuracy of amplicon-based massively parallel sequencing. Amplicon-based massively parallel sequencing was performed using the Illumina TruSeq® Amplicon Cancer Panel. Gene amplification was detected by quantitative PCR-based assay. Protein expression was determined by automated quantitative fluorescent immunohistochemistry.

Results

Data on genetic alterations were available for 126 patients. The median follow-up time was 1570 days. Amplicon-based massively parallel sequencing identified frequent gene alterations in TP53 (66.7%), PIK3CA (13.5%), APC (10.3%), ERBB4 (7.9%), and FBXW7 (7.9%). There was no association between clinicopathological features or prognosis with smoking status. Multivariate analyses revealed that the PIK3CA mutation and clinical T stage were independent favorable prognostic factors (hazard ratio 0.34, 95% confidence interval: 0.12–0.96, p = 0.042). PIK3CA mutations were significantly associated with APC alterations (p = 0.0007) and BRAF mutations (p = 0.0090).

Conclusions

Our study provided profiles of cancer-related genes in Japanese patients with esophageal cancer by next-generation sequencing using surgically resected formalin-fixed, paraffin-embedded tissue, and identified the PIK3CA mutation as a favorable prognosis biomarker.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4733-7) contains supplementary material, which is available to authorized users.

Establishment and genomic characterizations of patient-derived esophageal squamous cell carcinoma xenograft models using biopsies for treatment optimization

Background

Squamous cell carcinoma is the dominant type of esophageal cancer in China with many patients initially diagnosed at advanced stage. Patient-derived xenografts (PDX) models have been developed to be an important platform for preclinical research. This study aims to establish and characterize PDX models using biopsy tissue from advanced esophageal cancer patients to lay the foundation of preclinical application.

Methods

Fresh endoscopic biopsy tissues were harvested from patients with advanced esophageal cancer and implanted subcutaneously into NOD/SCID mice. Then, the PDXs were serially passaged for up to four generations. Transplantation was analyzed and genomic characteristics of xenografts were profiled using next-generation sequencing.

Results

Twenty-five PDX models were established (13.3%, 25/188). The latency period was 75.12 ± 19.87 days (50–120 days) for the first passage and it decreased with increasing passaging. Other than tumor stages, no differences were found between transplantations of xenografts and patient characteristics, irrespective of chemotherapy. Histopathological features and chemosensitivity of PDXs were in great accordance with primary patient tumors. Each PDX was assessed for molecular characteristics including copy number variations, somatic mutations, and signaling pathway abnormalities and these were similar to patient results.

Conclusions

Our PDX models were established from real time biopsies and molecularly profiled. They might be promising for drug development and individualized therapy.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1379-9) contains supplementary material, which is available to authorized users.

Establishment and evaluation of four different types of patient-derived xenograft models

Background

Patient-derived xenografts (PDX) have a biologically stable in tumor architecture, drug responsiveness, mutational status and global gene-expression patterns. Numerous PDX models have been established to date, however their thorough characterization regarding the tumor formation and rates of tumor growth in the established models remains a challenging task. Our study aimed to provide more detailed information for establishing the PDX models successfully and effectively.

Methods

We transplanted four different types of solid tumors from 108 Chinese patients, including 21 glioblastoma (GBM), 11 lung cancers (LC), 54 gastric cancers (GC) and 21 colorectal cancers (CRC), and took tumor tissues passaged for three successive generations. Here we report the rate of tumor formation, tumor-forming times, tumor growth curves and mortality of mice in PDX model. We also report H&E staining and immunohistochemistry for HLA-A, CD45, Ki67, GFAP, and CEA protein expression between patient cancer tissues and PDX models.

Results

Tumor formation rate increased significantly in subsequent tumor generations. Also, the survival rates of GC and CRC were remarkably higher than GBM and LC. As for the time required for the formation of tumors, which reflects the tumor growth rate, indicated that tumor growth rate always increased as the generation number increased. The tumor growth curves also illustrate this law. Similarly, the survival rate of PDX mice gradually improved with the increased generation number in GC and CRC. And generally, there was more proliferation (Ki67+) in the PDX models than in the patient tumors, which was in accordance with the results of tumor growth rate. The histological findings confirm similar histological architecture and degrees of differentiation between patient cancer tissues and PDX models with statistical analysis by GraphPad Prism 5.0.

Conclusion

We established four different types of PDX models successfully, and our results add to the current understanding of the establishment of PDX models and may contribute to the extension of application of different types of PDX models.

Esophageal Cancer: Genomic and Molecular Characterization, Stem Cell Compartment and Clonal Evolution

Esophageal cancer (EC) is the eighth most common cancer and is the sixth leading cause of death worldwide. The incidence of histologic subtypes of EC, esophageal adenocarcinoma (EAC) and esophageal squamous carcinoma (ESCC), display considerable geographic variation. EAC arises from metaplastic Barrett's esophagus (BE) in the context of chronic inflammation secondary to exposure to acid and bile. The main risk factors for developing ESCC are cigarette smoking and alcohol consumption. The main somatic genetic abnormalities showed a different genetic landscape in EAC compared to ESCC. EAC is a heterogeneous cancer dominated by copy number alterations, a high mutational burden, co-amplification of receptor tyrosine kinase, frequent TP53 mutations. The cellular origins of BE and EAC are still not understood: animal models supported a cellular origin either from stem cells located in the basal layer of esophageal epithelium or from progenitors present in the cardia region. Many studies support the existence of cancer stem cells (CSCs) able to initiate and maintain EAC or ESCC. The exact identification of these CSCs, as well as their role in the pathogenesis of EAC and ESCC remain still to be demonstrated. The reviewed studies suggest that current molecular and cellular characterization of EAC and ESCC should serve as background for development of new treatment strategies.

Establishment of patient-derived tumor xenograft (PDTX) models using samples from CT-guided percutaneous biopsy

This study aimed to investigate the feasibility of the establishment of a human cancer xenograft model using samples from computed tomography (CT)-guided percutaneous biopsy. Fresh tumor tissues obtained from 10 cancer patients by CT-guided percutaneous biopsy were subcutaneously inoculated into NOD-Prkdcem26Il2rgem26Nju (NCG) mice to establish human patient-derived tumor xenograft (PDTX) models. The formation of first and second generation xenografts was observed, and tumor volume was recorded over time. Tumor tissue consistency between the PDTX model and primary tumors in patients was compared using H&E staining and immunohistochemistry. Pharmacodynamic tests of clinically used chemotherapeutic drugs were conducted on second generation xenografts, and their effects on tumor growth and body weight were observed. CT-guided percutaneous biopsy samples were successfully collected from 10 patients with advanced cancers. The PDTX model was established in mice using tumor samples obtained from 4 cancer patients, including one small cell carcinoma sample, two adenocarcinoma samples, and one squamous cell carcinoma sample. The success rate was 40%. The obtained PDTX model maintained a degree of differentiation, and morphological and structural characteristics were similar to primary tumors. The pharmacodynamic test of chemotherapeutic drugs in the PDTX model revealed a therapeutic effect on tumor growth, as expected. CT-guided percutaneous biopsy samples can be effectively used to establish a PDTX model, and test these chemotherapy regimens.

Anti-tumor efficacy of theliatinib in esophageal cancer patient-derived xenografts models with epidermal growth factor receptor (EGFR) overexpression and gene amplification

Targeted therapy is not yet approved for esophageal cancer (EC). In this study, we first evaluated EGFR gene and protein expression in 70 Chinese EC patient tumor samples collected during surgery. We then established 23 patient-derived EC xenograft (PDECX) models and assessed the efficacy of theliatinib, a potent and highly selective EGFR inhibitor currently in Phase I clinical study, in 9 PDECX models exhibiting various EGFR expression levels. Immunohistochemical analysis showed that 50 patient tumor samples (71.4%) had high EGFR expression. Quantitative PCR showed that eight tumors (11.6%) had EGFR gene copy number gain, and fluorescence in situ hybridization (FISH) revealed that four tumors had EGFR gene amplification. These results suggest that EGFR protein may be overexpressed in many EC tumors without gene amplification. Also detected were rare hot-spot mutations in EGFR and PIK3CA, whereas no mutations were found in K-Ras or B-Raf. Theliatinib exhibited strong antitumor activity in PDECX models with high EGFR expression, including remarkable tumor regression in two PDECX models with both EGFR gene amplification and protein overexpression. However, the efficacy of theliatinib was diminished in models with PI3KCA mutations or FGFR1 overexpression in addition to high EGFR expression. This study demonstrates that theliatinib could potentially benefit EC patients with high EGFR protein expression without mutations or aberrant activities of associated factors, such as PI3KCA or FGFR1.

Laboratory animal models for esophageal cancer

The incidence of esophageal cancer is rapidly increasing especially in developing countries. The major risk factors include unhealthy lifestyle practices such as alcohol consumption, smoking, and chewing tobacco to name a few. Diagnosis at an advanced stage and poor prognosis make esophageal cancer one of the most lethal diseases. These factors have urged further research in understanding the pathophysiology of the disease. Animal models not only aid in understanding the molecular pathogenesis of esophageal cancer but also help in developing therapeutic interventions for the disease. This review throws light on the various recent laboratory animal models for esophageal cancer.

Patient-Derived Gastric Carcinoma Xenograft Mouse Models Faithfully Represent Human Tumor Molecular Diversity

Patient-derived cancer xenografts (PDCX) generally represent more reliable models of human disease in which to evaluate a potential drugs preclinical efficacy. However to date, only a few patient-derived gastric cancer xenograft (PDGCX) models have been reported. In this study, we aimed to establish additional PDGCX models and to evaluate whether these models accurately reflected the histological and genetic diversities of the corresponding patient tumors. By engrafting fresh patient gastric cancer (GC) tissues into immune-compromised mice (SCID and/or nude mice), thirty two PDGCX models were established. Histological features were assessed by a qualified pathologist based on H&E staining. Genomic comparison was performed for several biomarkers including ERBB1, ERBB2, ERBB3, FGFR2, MET and PTEN. These biomarkers were profiled to assess gene copy number by fluorescent in situ hybridization (FISH) and/or protein expression by immunohistochemistry (IHC). All 32 PDGCX models retained the histological features of the corresponding human tumors. Furthermore, among the 32 models, 78% (25/32) highly expressed ERBB1 (EGFR), 22% (7/32) were ERBB2 (HER2) positive, 78% (25/32) showed ERBB3 (HER3) high expression, 66% (21/32) lost PTEN expression, 3% (1/32) harbored FGFR2 amplification, 41% (13/32) were positive for MET expression and 16% (5/32) were MET gene amplified. Between the PDGCX models and their parental tumors, a high degree of similarity was observed for FGFR2 and MET gene amplification, and also for ERBB2 status (agreement rate = 94~100%; kappa value = 0.81~1). Protein expression of PTEN and MET also showed moderate agreement (agreement rate = 78%; kappa value = 0.46~0.56), while ERBB1 and ERBB3 expression showed slight agreement (agreement rate = 59~75%; kappa value = 0.18~0.19). ERBB2 positivity, FGFR2 or MET gene amplification was all maintained until passage 12 in mice. The stability of the molecular profiles observed across subsequent passages within the individual models provides confidence in the utility and translational significance of these models for in vivo testing of personalized therapies.

Personalized targeted therapy for esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma continues to heavily burden clinicians worldwide. Researchers have discovered the genomic landscape of esophageal squamous cell carcinoma, which holds promise for an era of personalized oncology care. One of the most pressing problems facing this issue is to improve the understanding of the newly available genomic data, and identify the driver-gene mutations, pathways, and networks. The emergence of a legion of novel targeted agents has generated much hope and hype regarding more potent treatment regimens, but the accuracy of drug selection is still arguable. Other problems, such as cancer heterogeneity, drug resistance, exceptional responders, and side effects, have to be surmounted. Evolving topics in personalized oncology, such as interpretation of genomics data, issues in targeted therapy, research approaches for targeted therapy, and future perspectives, will be discussed in this editorial.

The prognostic value of EGFR overexpression and amplification in Esophageal squamous cell Carcinoma

BACKGROUND

In view of the prominent role in cancer cell biology and alteration in substantial numbers of ESCC, defining EGFR molecular characteristics relevant to patient prognosis is of great importance. Therefore, we analyzed the protein expression and gene copy variation of the epithelial growth factor receptor (EGFR) in Chinese esophageal squamous cell carcinoma (ESCC) and explored the possible associations with various features of the tumors and survival of the patients.

METHODS

Sections were made from tissue microarray composed of 96 ESCC, and examined for EGFR expression by means of immunohistochemistry (IHC) and for EGFR gene amplification by means of fluorescence in situ hybridization (FISH). The results of IHC were evaluated with six different reported scoring systems. Correlation with clinical features and survival was evaluated using chi-square test and Kaplan-Meier analysis.

RESULTS

EGFR overexpression according to scoring system 1 significantly correlated with advanced lymph node involvement (P = 0.046), patient disease specific free survival (DFS) (P = 0.006) and overall survival (OS) (P = 0.007). No such association was observed using other 5 scoring systems (P > 0.05 ). EGFR amplification was associated with lymph node metastasis (P = 0.028), but not correlated with DFS and OS until 20 months.

CONCLUSIONS

EGFR IHC overexpression evaluated by scoring system 1 might be suitable to be used in predicting patients survival in ESCC. EGFR gene amplification showed delayed prognostic information after 20 months.

Intramuscular Transplantation Improves Engraftment Rates for Esophageal Patient-Derived Tumor Xenografts

BACKGROUND

Recently, there has been an increase in the availability of targeted molecular therapies for cancer treatment. The application of these approaches to esophageal cancer, however, has been hampered by the relative lack of appropriate models for preclinical testing. Patient-derived tumor xenograft (PDTX) models are gaining popularity for studying many cancers. Unfortunately, it has proven difficult to generate xenografts from esophageal cancer using these models. The purpose of this study was to improve the engraftment efficiency of esophageal PDTXs.

METHODS

Fresh pieces of esophageal tumors obtained from endoscopic biopsies or resected specimens were collected from 23 patients. The tumors were then coated in Matrigel and transplanted in immunocompromised mice subcutaneously (n = 6) and/or using a novel implantation technique whereby the tumor is placed in a dorsal intramuscular pocket (n = 18). They are then monitored for engraftment.

RESULTS

With the novel intramuscular technique, successful engraftment was achieved for all 18 patient tumors. Among these PDTXs, 13 recapitulated the original patient tumors with respect to degree of differentiation, molecular and genetic profiles, and chemotherapeutic response. Lymphomatous transformation was observed in the other five PDTXs. Successful engraftment was achieved for only one of six patient tumors using the classic subcutaneous approach.

DISCUSSION

We achieved a much higher engraftment rate of PDTXs using our novel intramuscular transplant technique than has been reported in other published studies. It is hoped that this advancement will help expedite the development and testing of new therapies for esophageal cancer.