Current management of succinate dehydrogenase-deficient gastrointestinal stromal tumors

USP5 Promotes Ripretinib Resistance in Gastrointestinal Stromal Tumors by MDH2 Deubiquition

Ripretinib, a broad-spectrum inhibitor of the KIT and PDGFRA receptor tyrosine kinases, is designated as a fourth-line treatment for gastrointestinal stromal tumor (GIST). It is tailored for patients resistant to imatinib, sunitinib, and regorafenib. As its increasing use, instances of resistance to ripretinib are becoming more frequent. Unfortunately, there are currently no scientifically mature treatment options available for patients resistant to ripretinib. Posttranslational modifications (PTMs) such as ubiquitination, in conjunction with its interplay with other modifications, play a collective role in regulating tumor initiation and progression. However, the specific association between ubiquitination and ripretinib resistance is not reported. Through proteome-ubiquitinome sequencing, increased levels of the USP5 protein and decreased ubiquitination in ripretinib-resistant GISTs are detected. Subsequent examination of the mass spectrometry findings validated the interaction through which TRIM21 governs USP5 expression via ubiquitination, and USP5 regulates MDH2 expression through deubiquitination, consequently fostering ripretinib resistance in GIST. Moreover, ZDHHC18 can palmitoylate MDH2, preventing its ubiquitination and further increasing its protein stability. The research underscores the correlation between posttranslational modifications, specifically ubiquitination, and drug resistance, emphasizing the potential of targeting the USP5-MDH2 axis to counteract ripretinib resistance in GIST.

Decoding mitochondria's role in immunity and cancer therapy

The functions of mitochondria, including energy production and biomolecule synthesis, have been known for a long time. Given the rising incidence of cancer, the role of mitochondria in cancer has become increasingly popular. Activated by components released by mitochondria, various pathways interact with each other to induce immune responses to protect organisms from attack. However, mitochondria play dual roles in the progression of cancer. Abnormalities in proteins, which are the elementary structures of mitochondria, are closely linked with oncogenesis. Both the aberrant accumulation of intermediates and mutations in enzymes result in the generation and progression of cancer. Therefore, targeting mitochondria to treat cancer may be a new strategy. Several drugs aimed at inhibiting mutated enzymes and accumulated intermediates have been tested clinically. Here, we discuss the current understanding of mitochondria in cancer and the interactions between mitochondrial functions, immune responses, and oncogenesis. Furthermore, we discuss mitochondria as hopeful targets for cancer therapy, providing insights into the progression of future therapeutic strategies.

Research progress on the pathogenesis of the SDHB mutation and related diseases

With the improvement of genetic testing technology in diseases in recent years, researchers have a more detailed and clear understanding of the source of cancers. Succinate dehydrogenase B (SDHB), a mitochondrial gene, is related to the metabolic activities of cells and tissues throughout the body. The mutations of SDHB have been found in pheochromocytoma, paraganglioma and other cancers, and is proved to affect the occurrence and progress of those cancers due to the important structural functions. The importance of SDHB is attracting more and more attention of researchers, however, reviews on the structure and function of SDHB, as well as on the mechanism of its carcinogenesis is inadequate. This paper reviews the relationship between SDHB mutations and related cancers, discusses the molecular mechanism of SDHB mutations that may lead to tumor formation, analyzes the mutation spectrum, structural domains, and penetrance of SDHB and sorts out some of the previously discovered diseases. For the patients with SDHB mutation, it is recommended that people in SDHB mutation families undergo regular genetic testing or SDHB immunohistochemistry (IHC). The purpose of this paper is hopefully to provide some reference and help for follow-up researches on SDHB.

Succinate metabolism: a promising therapeutic target for inflammation, ischemia/reperfusion injury and cancer

Succinate serves as an essential circulating metabolite within the tricarboxylic acid (TCA) cycle and functions as a substrate for succinate dehydrogenase (SDH), thereby contributing to energy production in fundamental mitochondrial metabolic pathways. Aberrant changes in succinate concentrations have been associated with pathological states, including chronic inflammation, ischemia/reperfusion (IR) injury, and cancer, resulting from the exaggerated response of specific immune cells, thereby rendering it a central area of investigation. Recent studies have elucidated the pivotal involvement of succinate and SDH in immunity beyond metabolic processes, particularly in the context of cancer. Current scientific endeavors are concentrated on comprehending the functional repercussions of metabolic modifications, specifically pertaining to succinate and SDH, in immune cells operating within a hypoxic milieu. The efficacy of targeting succinate and SDH alterations to manipulate immune cell functions in hypoxia-related diseases have been demonstrated. Consequently, a comprehensive understanding of succinate's role in metabolism and the regulation of SDH is crucial for effectively targeting succinate and SDH as therapeutic interventions to influence the progression of specific diseases. This review provides a succinct overview of the latest advancements in comprehending the emerging functions of succinate and SDH in metabolic processes. Furthermore, it explores the involvement of succinate, an intermediary of the TCA cycle, in chronic inflammation, IR injury, and cancer, with particular emphasis on the mechanisms underlying succinate accumulation. This review critically assesses the potential of modulating succinate accumulation and metabolism within the hypoxic milieu as a means to combat various diseases. It explores potential targets for therapeutic interventions by focusing on succinate metabolism and the regulation of SDH in hypoxia-related disorders.

Surgical Management of Germline Gastrointestinal Stromal Tumor

Gastrointestinal stromal tumor (GIST) is the most common human sarcoma and usually results from a sporadic mutation in KIT or, less frequently, platelet-derived growth factor alpha (PDGFRA). Rarely, a germline mutation in the KIT, PDGFRA, succinate dehydrogenase (SDH), or neurofibromatosis 1 (NF1) gene is responsible for GIST. These tumors are found in the stomach (PDGFRA and SDH), small bowel (NF1), or a combination of both (KIT). There is a need to improve care for these patients regarding genetic testing, screening, and surveillance. Since most GISTs due to a germline mutation do not respond to tyrosine kinase inhibitors, the role of surgery is critical, especially when considering germline gastric GIST. However, in contrast to the established recommendation for prophylactic total gastrectomy in cadherin 1 (CDH1) mutation carriers once they reach adulthood, there are no formal guidelines as to the timing or extent of surgical resection for patients who are either carriers of a germline GIST mutation causing gastric GIST or have already developed gastric GIST(s). Surgeons must balance treating what is often multicentric, yet initially indolent disease with the chance of cure and the complications associated with total gastrectomy. Here, we consider the major issues in performing surgery in patients with germline GIST and illustrate the principles with a previously unreported patient harboring a germline KIT 579 deletion.

Prognostic analysis of 2-5 cm diameter gastric stromal tumors with exogenous or endogenous growth

BACKGROUND

There has been limited research on the prognosis differences in patients with gastric stromal tumor invasion of the plasma membrane surface. This study intended to investigate whether there is a difference in prognosis in patients with endogenous or exogenous 2-5 cm diameter GISTs.

METHODS

We retrospectively analyzed the clinicopathological and follow-up data of gastric stromal tumor patients, all of whom underwent surgical resection for primary GIST at Nanjing Drum Tower Hospital from December 2010 to February 2022. We classified patients based on tumor growth patterns and then investigated the association between tumor growth patterns and clinical outcomes. Progression-free survival (PFS) and overall survival (OS) were calculated by the Kaplan‒Meier method.

RESULTS

A total of 496 gastric stromal tumor patients were enrolled in this study, among which 276 patients had tumors of 2-5 cm in diameter. Of these 276 patients, 193 had exogenous tumors, and 83 had endogenous tumors. Tumor growth patterns were significantly related to age, rupture status, resection style, tumor site, tumor size, and intraoperative bleeding. According to Kaplan‒Meier curve analysis, the tumor growth pattern among patients with 2-5 cm diameter tumors was significantly correlated with worse progression-free survival (PFS). Ultimately, multivariate analyses identified the Ki-67 index (P = 0.008), surgical history (P = 0.031), and resection style (P = 0.045) as independent prognostic markers for PFS.

CONCLUSIONS

Although gastric stromal tumors with a diameter of 2-5 cm are classified as low risk, the prognosis is lower for exogenous tumors than for endogenous tumors, and exogenous gastric stromal tumors have a risk of recurrence. Consequently, clinicians should be vigilant regarding the prognosis of patients with this type of tumor.

Current status of and future prospects for the treatment of unresectable or metastatic gastrointestinal stromal tumours

Gastrointestinal stromal tumours (GISTs) are soft-tissue sarcomas of the gastrointestinal tract. Surgery is the standard treatment for localised disease, but the risk of relapse and progression to more advanced disease is substantial. Following the discovery of the molecular mechanisms underlying GISTs, targeted therapies for advanced GIST were developed, with the first being the tyrosine kinase inhibitor (TKI) imatinib. Imatinib is recommended in international guidelines as first-line therapy to reduce the risk of GIST relapse in high-risk patients, and for locally advanced, inoperable and metastatic disease. Unfortunately, imatinib resistance frequently occurs and, therefore, second-line (sunitinib) and third-line (regorafenib) TKIs have been developed. Treatment options are limited for patients with GIST that has progressed despite these therapies. A number of other TKIs for advanced/metastatic GIST have been approved in some countries. Ripretinib is approved as fourth-line treatment of GIST and avapritinib is approved for GIST harbouring specific genetic mutations, while larotrectinib and entrectinib are approved for solid tumours (including GIST) with specific genetic mutations. In Japan, pimitespib, a heat shock protein 90 (HSP90) inhibitor, is now available as a fourth-line therapy for GIST. Clinical studies of pimitespib have indicated that it has good efficacy and tolerability, importantly not displaying the ocular toxicity of previously developed HSP90 inhibitors. Additional approaches for advanced GIST have been investigated, including alternative uses of currently available TKIs (such as combination therapy), novel TKIs, antibody-drug conjugates, and immunotherapies. Given the poor prognosis of advanced GIST, the development of new therapies remains an important goal.

An unusual paraesophageal and diaphragmatic SDHA-deficient gastrointestinal stromal tumor (GIST) metastases case report

Background

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract and have diverse tumor biology. Succinate dehydrogenase (SDH)-deficient GIST, comprise less than 10% of all GIST, with mutational loss of the catalytic SDHA subunit being the most common subtype. Contrary to typical GISTs harboring inactivating mutations in KIT/PDGFRA, SDH-deficient GIST has varying biology and behavior, occurring at a younger age, often metastatic on presentation and frequently refractory to conventional tyrosine kinase inhibitors (TKI). Liver and peritoneum are their most common sites of metastases, and extra-abdominal spread to the diaphragm or mediastinum has not been previously described.

Case Description

Herein, we present a case of a 44-year-old female patient with a history of SDHA-deficient GISTs with multiple previous metastasectomies who presented with recurrence to the paraesophageal region and diaphragm which was identified upon routine positron emission tomography (PET) surveillance. Patient subsequently underwent a robotic assisted metastasectomy using a thoracic approach. Follow up was obtained 2 months following procedure and there was no evidence of recurrence.

Conclusions

SDHA-deficient GISTs have unique tumor biology and management of metastatic lesions remains an area of debate and discovery. Overall, this report highlights the need for comprehensive knowledge of the disease, a skilled surgical team, and multi-disciplinary involvement in order to optimize care and ensure favorable outcomes in this patient population.

TKI Treatment Sequencing in Advanced Gastrointestinal Stromal Tumors

Prior to the early 2000s, patients with advanced gastrointestinal stromal tumors (GIST) had very poor prognoses owing to a lack of effective therapies. The development of tyrosine kinase inhibitors at the turn of the century significantly improved the overall survival for patients with GIST. The resounding success of imatinib in the first clinical trial of a tyrosine kinase inhibitor to treat GIST led to its approval for first-line therapy for advanced GIST; this study was open to all comers and not restricted to any GIST subtype(s). The trials that led to the approvals of second-, third-, and fourth-line therapy for advanced GIST were also open to all patients with advanced/metastatic GIST. Only in retrospect do we realize the role that the molecular subtypes played in the results observed in these studies. In this review, we discuss the studies that led to the US Food and Drug Administration approval of imatinib (first line), sunitinib (second line), regorafenib (third line), and ripretinib (fourth line) for advanced KIT-mutant GIST. In addition, we review how information about GIST molecular subtypes has been used to accelerate the approval of other targeted therapies for non-KIT mutant GIST, leading to the approval of five additional drugs indicated for the treatment of specific GIST molecular subtypes. We also discuss how our understanding of the molecular subtypes will play a role in the next generation of therapeutic approaches for treating advanced GIST.

Latest Advances in the Management of Pediatric Gastrointestinal Stromal Tumors

Gastrointestinal stromal tumor is the most common mesenchymal neoplasm of the gastrointestinal tract, usually found in elderly adults. It is infrequent among pediatric patients and usually differs biologically from adult-type diseases presenting mutations of KIT and PDGFR genes. In this population, more frequent is the wild-type GIST possessing SDH, TRK, RAS, NF1 mutations, among others. Both tumor types require individualized treatment with kinase inhibitors that are still being tested in the pediatric population due to the different neoplasm biology. We review the latest updates to the management of pediatric gastrointestinal tumors with a particular focus on the advances in molecular biology of the disease that enables the definition of possible resistance. Emerging treatment with kinase inhibitors that could serve as targeted therapy is discussed, especially with multikinase inhibitors of higher generation, the effectiveness of which has already been confirmed in the adult population.

Metastatic SDH-Deficient GIST Diagnosed during Pregnancy: Approach to a Complex Case

Gastrointestinal stromal tumors (GISTs) account for 1% of GI neoplasms in adults, and epidemiological data suggest an even lower occurrence in pregnant women. The majority of GISTs are caused by KIT and PDGFRA mutations. This is not the case in women of childbearing age. Some GISTs do not have a KIT/PDGFRA mutation and are classified as wild-type (WT) GISTs. WT-GIST includes many molecular subtypes including SDH deficiencies. In this paper, we present the first case report of a metastatic SDH-deficient GIST in a 23-year-old pregnant patient and the challenges encountered given her concurrent pregnancy. Our patient underwent a surgical tumor resection of her gastric GIST as well as a lymphadenectomy a week after induction of labor at 37 + 1 weeks. She received imatinib, sunitinib as well as regorafenib afterward. These drugs were discontinued because of disease progression despite treatment or after side effects were reported. Hence, she is currently under treatment with ripretinib. Her last FDG-PET showed a stable disease. This case highlights the complexity of GI malignancy care during pregnancy, and the presentation and management particularities of metastatic WT-GISTs. This case also emphasizes the need for a multidisciplinary approach and better clinical guidelines for offering optimal management to women in this specific context.

The KDM6A-SPARCL1 axis blocks metastasis and regulates the tumour microenvironment of gastrointestinal stromal tumours by inhibiting the nuclear translocation of p65

BACKGROUND

It is urgent to explore the pathogenic mechanism of gastrointestinal stromal tumours (GISTs). KDM6A, a histone demethylase, can activate gene transcription and has not been reported in GISTs. SPARCL1 may serve as a metastasis marker in GIST, but the molecular mechanism remains to be further explored. This study aimed to explore the biological function and molecular mechanism of KDM6A and SPARCL1 in GIST.

METHODS

CCK-8, live cell count, colony formation, wound-healing and Transwell migration and invasion assays were employed to detect the cell proliferation, migration and invasion. A xenograft model and hepatic metastasis model were used to assess the role of KDM6A and SPARCL1 in vivo.

RESULTS

KDM6A inhibited the proliferation, migration and invasion of GIST cells. Mechanistically, KDM6A promotes the transcription of SPARCL1 by demethylating histone H3 lysine trimethylation and consequently leads to the inactivation of p65. SPARCL1 affected the metastasis of GIST cells in a mesenchymal-epithelial transition- and matrix-metalloproteinase-dependent manner. SPARCL1 knockdown promoted angiogenesis, M2 polarisation and macrophage recruitment by inhibiting the phosphorylation of p65. Moreover, KDM6A and SPARCL1 inhibited hepatic metastasis and macrophage infiltration in vivo.

CONCLUSIONS

Our findings establish the critical role of the KDM6A-SPARCL1-p65 axis in restraining the malignancy of GIST.

Oncometabolites-A Link between Cancer Cells and Tumor Microenvironment

The tumor microenvironment is the space between healthy tissues and cancer cells, created by the extracellular matrix, blood vessels, infiltrating cells such as immune cells, and cancer-associated fibroblasts. These components constantly interact and influence each other, enabling cancer cells to survive and develop in the host organism. Accumulated intermediate metabolites favoring dysregulation and compensatory responses in the cell, called oncometabolites, provide a method of communication between cells and might also play a role in cancer growth. Here, we describe the changes in metabolic pathways that lead to accumulation of intermediate metabolites: lactate, glutamate, fumarate, and succinate in the tumor and their impact on the tumor microenvironment. These oncometabolites are not only waste products, but also link all types of cells involved in tumor survival and progression. Oncometabolites play a particularly important role in neoangiogenesis and in the infiltration of immune cells in cancer. Oncometabolites are also associated with a disrupted DNA damage response and make the tumor microenvironment more favorable for cell migration. The knowledge summarized in this article will allow for a better understanding of associations between therapeutic targets and oncometabolites, as well as the direct effects of these particles on the formation of the tumor microenvironment. In the future, targeting oncometabolites could improve treatment standards or represent a novel method for fighting cancer.

Multiple, large intra-abdominal cystic lesions and iron deficiency anaemia as the presenting symptoms of SDHD gastrointestinal stromal tumour (GIST) in a young sub-Saharan woman

We report the case of a 27-year-old female patient from sub-Saharan Africa who presented with non-specific abdominal complaints, iron deficiency anaemia and multiple, large intra-abdominal cystic lesions on imaging. The lesions appeared to be a most unusual presentation of gastrointestinal stromal tumour (GIST). GIST is a sarcomatous tumour that comprises only 0.2% of all gastrointestinal (GI) tumours; it is the most common mesenchymal malignancy of the GI tract. Our patient had the succinate dehydrogenase-deficient (SDHD) subtype, identified in some 5%-10% of patients with GIST only, commonly found in women and younger patients. The differential diagnosis of intra-abdominal cystic lesions is briefly discussed, including the relevance of a correct pathological diagnosis. This impacts medical and surgical management decisions, including predicting response to targeted therapy. Tyrosine kinase inhibitor therapy has been a breakthrough in the treatment of GISTs, although with extensive disease, and certainly in case of the SDHD subtype, long-term outcome remains disappointing.

Establishment of Patient-Derived Succinate Dehydrogenase-Deficient Gastrointestinal Stromal Tumor Models for Predicting Therapeutic Response

PURPOSE

Gastrointestinal stromal tumor (GIST) is the most common sarcoma of the gastrointestinal tract, with mutant succinate dehydrogenase (SDH) subunits (A-D) comprising less than 7.5% (i.e., 150-200/year) of new cases annually in the United States. Contrary to GISTs harboring KIT or PDGFRA mutations, SDH-mutant GISTs affect adolescents/young adults, often metastasize, and are frequently resistant to tyrosine kinase inhibitors (TKI). Lack of human models for any SDH-mutant tumors, including GIST, has limited molecular characterization and drug discovery.

EXPERIMENTAL DESIGN

We describe methods for establishing novel patient-derived SDH-mutant (mSDH) GIST models and interrogated the efficacy of temozolomide on these tumor models in vitro and in clinical trials of patients with mSDH GIST.

RESULTS

Molecular and metabolic characterization of our patient-derived mSDH GIST models revealed that these models recapitulate the transcriptional and metabolic hallmarks of parent tumors and SDH deficiency. We further demonstrate that temozolomide elicits DNA damage and apoptosis in our mSDH GIST models. Translating our in vitro discovery to the clinic, a cohort of patients with SDH-mutant GIST treated with temozolomide (n = 5) demonstrated a 40% objective response rate and 100% disease control rate, suggesting that temozolomide represents a promising therapy for this subset of GIST.

CONCLUSIONS

We report the first methods to establish patient-derived mSDH tumor models, which can be readily employed for understanding patient-specific tumor biology and treatment strategies. We also demonstrate that temozolomide is effective in patients with mSDH GIST who are refractory to existing chemotherapeutic drugs (namely, TKIs) in clinic for GISTs, bringing a promising treatment option for these patients to clinic.

Gastrointestinal Stromal Tumors-A Mini Review

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. They are potentially malignant, and have an unpredictable evolution. The origin of these tumors is in the interstitial cells of Cajal, which are cells that are interposed between the intramural neurons and the smooth muscle cells of the digestive tract. GISTs are characterized by mutations in the gene c-Kit, but also other mutations, such as those of the platelet-derived growth factor receptor alpha. The most common locations of these tumors are the stomach and small intestine, although they can occur at any level of the digestive tract and occasionally in the omentum, mesentery and peritoneum. Most cases of GISTs are sporadic, and about 5% of cases are part of family genetic syndromes. The correct diagnosis of GIST is determined by histopathological examination and immunohistochemistry. According to histopathology, there are three main types of GISTs: spindle cell type, epithelioid type and mixed type. The therapeutic management of GIST includes surgery, endoscopic treatment and chemotherapy. The prognosis of patients with GIST varies depending on a number of factors, such as risk category, GIST stage, treatment applied and recurrence after treatment.

New treatments in advanced gastrointestinal stromal tumor

PURPOSE OF REVIEW

The current article revisits the most recent advances that occurred in the field of gastrointestinal stromal tumor (GIST) therapeutics.

RECENT FINDINGS

GIST is driven by the oncogenic activation of KIT or PDGFRA receptor tyrosine kinases, and agents targeting these receptors lead to substantial benefit throughout the entire course of the disease. Two new drugs were approved in 2020. On one hand, ripretinib obtained the regulatory approval for the treatment of GIST patients after progression to all standard treatments. On the other hand, avapritinib became the first agent ever displaying activity in GIST driven by the multiresistant PDGFRA D842V mutation. The addition of both drugs to GIST therapeutics constitutes a remarkable milestone, particularly considering that the last agent approved was back in 2012. Similarly, the recent identification of neurotrophic tyrosine receptor kinase (NTRK) fusions in a subset of KIT/PDGFRA wild-type GISTs led to an open window for tailored treatment using specific NTRK inhibitors. Finally, multiple efforts have been made toward the clinical implementation of circulating tumor DNA evaluation to guide clinical decisions in GIST.

SUMMARY

GIST has been consolidated over the years as a paradigmatic model in personalized medicine for the successful development of novel therapeutic strategies through targeted inhibition of oncogenic drivers.

Value of radiomics model based on enhanced computed tomography in risk grade prediction of gastrointestinal stromal tumors

To explore the application of computed tomography (CT)-enhanced radiomics for the risk-grade prediction of gastrointestinal stromal tumors (GIST). GIST patients (n = 292) confirmed by surgery or endoscopic pathology during June 2013–2019 were reviewed and categorized into low-grade (very low to low risk) and high-grade (medium to high risk) groups. The tumor region of interest (ROI) was depicted layer by layer on each patient’s enhanced CT venous phase images using the ITK-SNAP. The texture features were extracted using the Analysis Kit (AK) and then randomly divided into the training (n = 205) and test (n = 87) groups in a ratio of 7:3. After dimension reduction by the least absolute shrinkage and the selection operator algorithm (LASSO), a prediction model was constructed using the logistic regression method. The clinical data of the two groups were statistically analyzed, and the multivariate regression prediction model was constructed by using statistically significant features. The ROC curve was applied to evaluate the prediction performance of the proposed model. A radiomics-prediction model was constructed based on 10 characteristic parameters selected from 396 quantitative feature parameters extracted from the CT images. The proposed radiomics model exhibited effective risk-grade prediction of GIST. For the training group, the area under curve (AUC), sensitivity, specificity, and accuracy rate were 0.793 (95%CI: 0.733–0.854), 83.3%, 64.3%, and 72.7%, respectively; the corresponding values for the test group were 0.791 (95%CI: 0.696–0.886), 84.2%, 69.3%, and 75.9%, respectively. There were significant differences in age (t value: − 3.133, P = 0.008), maximum tumor diameter (Z value: − 12.163, P = 0.000) and tumor morphology (χ² value:10.409, P = 0.001) between the two groups, which were used to establish a clinical prediction model. The area under the receiver operating characteristic curve of the clinical model was 0.718 (95%CI: 0.659–0.776). The proposed CT-enhanced radiomics model exhibited better accuracy and effective performance than the clinical model, which can be used for the assessment of risk grades of GIST.

Targeting Mitochondrial Oncometabolites: A New Approach to Overcome Drug Resistance in Cancer

Drug resistance is the main obstacle for a successful cancer therapy. There are many mechanisms by which cancers avoid drug-mediated death, including alterations in cellular metabolism and apoptotic programs. Mitochondria represent the cell's powerhouse and the connection between carbohydrate, lipid and proteins metabolism, as well as crucial controllers of apoptosis, playing an important role not only in tumor growth and progression, but also in drug response. Alterations in tricarboxylic acid cycle (TCA) caused by mutations in three TCA enzymes-isocitrate dehydrogenase, succinate dehydrogenase and fumarate hydratase-lead to the accumulation of 2-hydroxyglutarate, succinate and fumarate respectively, collectively known as oncometabolites. Oncometabolites have pleiotropic effects on cancer biology. For instance, they generate a pseudohypoxic phenotype and induce epigenetic changes, two factors that may promote cancer drug resistance leading to disease progression and poor therapy outcome. This review sums up the most recent findings about the role of TCA-derived oncometabolites in cancer aggressiveness and drug resistance, highlighting possible pharmacological strategies targeting oncometabolites production in order to improve the efficacy of cancer treatment.

Pediatric Gastrointestinal Stromal Tumors and Neuroendocrine Tumors: Advances in Surgical Management

Gastrointestinal stromal tumors and neuroendocrine tumors in adult and pediatric populations differ immensely. Despite these established differences, the extreme rarity of gastrointestinal stromal tumors and neuroendocrine tumors in the pediatric population has resulted in the lack of consensus management guidelines, making optimal surgical approaches unclear. Comprehensive management principles to guide surgical approaches in adult literature are extensive. However, these are still lacking for pediatric patients. International cooperation to develop standardized pediatric-specific guidelines is urgently warranted in the future. This article highlights the vast differences between adult and pediatric parameters and provides recommendations on optimal and novel surgical approaches in children.

Targeted therapy for upper gastrointestinal tract cancer: current and future prospects

Gastric and oesophageal carcinoma remain major causes of worldwide mortality and morbidity. Despite incredible progress in understanding tumour biology, few targeted treatment options have proved effective in prolonging survival, and adjuvant therapy is largely interchangeable in these carcinomas. Through large-scale sequencing by the Cancer Genome Atlas and the Asian Cancer Research Group, numerous potential molecular targets have been discovered. Of the approved targeted therapies for gastric and oesophageal cancer, pathologists play a role in patient selection for the majority of them. Trastuzumab has been approved as a first-line therapy in conjunction with standard treatment in adenocarcinomas with either 3+ HER2/neu expression by immunohistochemistry or ERBB2 amplification by FISH. PD-L1 immunohistochemistry showing a combined positive score of 1 or greater qualifies patients for third-line pembrolizumab therapy, and identification of microsatellite instability-high carcinomas may qualify patients for second-line pembrolizumab. Ramucirumab, targeting VEGFR2, has also been approved for second-line therapy in gastric carcinoma. Non-surgical therapy for gastrointestinal stromal tumours relies mainly upon tyrosine kinase inhibitors, while new targeted therapy options for neuroendocrine neoplasms have recently emerged. Potential future options for targeted therapy in all these malignancies are being investigated in clinical trials, as this review will discuss.

Clinical features of multiple gastrointestinal stromal tumors: A pooling analysis combined with evidence and gap map

BACKGROUND

Multiple gastrointestinal stromal tumors (MGISTs) are a very rare type of gastrointestinal stromal tumor (GIST) and are usually observed in syndrome.

AIM

The paper aimed to describe the clinical and oncological features of MGISTs and to offer evidence for the diagnosis and treatment.

METHODS

Data of consecutive patients with MGISTs who were diagnosed at Peking University People’s Hospital (PKUPH) from 2008 to 2019 were retrospectively evaluated. Further, a literature search was conducted by retrieving data from PubMed, EMBASE, and the Cochrane library databases from inception up to November 30, 2019.

RESULTS

In all, 12 patients were diagnosed with MGISTs at PKUPH, and 43 published records were ultimately included following the literature review. Combined analysis of the whole individual patient data showed that female (59.30%), young (14.45%), and syndromic GIST (63.95%) patients comprised a large proportion of the total patient population. Tumors were mainly located in the small intestine (58.92%), and both CD117 and CD34 were generally positive. After a mean 78.32-mo follow-up, the estimated median overall survival duration (11.5 years) was similar to single GISTs, but recurrence-free survival was relatively poorer.

CONCLUSION

The clinical and oncological features are potentially different between MGISTs and single GIST. Further studies are needed to explore appropriate surgical approach and adjuvant therapy.

Carney-Stratakis syndrome: A dyad of familial paraganglioma and gastrointestinal stromal tumor

Carney-Stratakis syndrome is a rare, distinct dyad of familial paraganglioma and gastrointestinal stromal tumor, and is associated with germline mutations in the succinate dehydrogenase genes SDHB, SDHC, and SDHD. We present a unique case of a 45-year-old woman with Carney-Stratakis syndrome who initially presented with a palpable left neck mass. Further workup demonstrated 2 paragangliomas in the neck and multiple SDHB deficient gastrointestinal stromal tumors of the stomach. We describe the imaging findings and clinical course of this rare syndrome.