Fibroblast Growth Factor Receptor (FGFR) Signaling in GIST and Soft Tissue Sarcomas

Sarcomas are a heterogeneous group of rare malignancies originating from mesenchymal tissues with limited therapeutic options. Recently, alterations in components of the fibroblast growth factor receptor (FGFR) signaling pathway have been identified in a range of different sarcoma subtypes, most notably gastrointestinal stromal tumors, rhabdomyosarcomas, and liposarcomas. These alterations include genetic events such as translocations, mutations, and amplifications as well as transcriptional overexpression. Targeting FGFR has therefore been proposed as a novel potential therapeutic approach, also in light of the clinical activity shown by multi-target tyrosine kinase inhibitors in specific subtypes of sarcomas. Despite promising preclinical evidence, thus far, clinical trials have enrolled very few sarcoma patients and the efficacy of selective FGFR inhibitors appears relatively low. Here, we review the known alterations of the FGFR pathway in sarcoma patients as well as the preclinical and clinical evidence for the use of FGFR inhibitors in these diseases. Finally, we discuss the possible reasons behind the current clinical data and highlight the need for biomarker stratification to select patients more likely to benefit from FGFR targeted therapies.

CT Radiomics Model for Discriminating the Risk Stratification of Gastrointestinal Stromal Tumors: A Multi-Class Classification and Multi-Center Study

Objective

To establish and verify a computed tomography (CT)-based multi-class prediction model for discriminating the risk stratification of gastrointestinal stromal tumors (GISTs).

Materials and Methods

A total of 381 patients with GISTs were confirmed by surgery and pathology. Information on 213 patients were obtained from one hospital and used as training cohort, whereas the details of 168 patients were collected from two other hospitals and used as independent validation cohort. Regions of interest on CT images of arterial and venous phases were drawn, radiomics features were extracted, and dimensionality reduction processing was performed. Using a one-vs-rest method, a Random Forest-based GISTs risk three-class prediction model was established, and the receiver operating characteristic curve (ROC) was used to evaluate the performance of the multi-class classification model, and the generalization ability was verified using external data.

Results

The training cohort included 96 very low-risk and low-risk, 60 intermediate-risk and 57 high-risk patients. External validation cohort included 82 very low-risk and low-risk, 48 intermediate-risk and 38 high-risk patients. The GISTs risk three-class radiomics model had a macro/micro average area under the curve (AUC) of 0.84 and an accuracy of 0.78 in the training cohort. It had a stable performance in the external validation cohort, with a macro/micro average AUC of 0.83 and an accuracy of 0.80.

Conclusion

CT radiomics can discriminate GISTs risk stratification. The performance of the three-class radiomics prediction model is good, and its generalization ability has also been verified in the external validation cohort, indicating its potential to assist stratified and accurate treatment of GISTs in the clinic.

KIT Mutation in Gastric Gastrointestinal Stromal Tumor in a Patient With Familial Paraganglioma Syndrome Type 4

Objective

Familial paraganglioma syndrome type 4 is associated with mutations in the succinate dehydrogenase complex subunit B (SDHB) gene. We report the case of a patient with familial paraganglioma syndrome type 4 with the mutation c.600G>T; p.Trp200Cys who developed a gastric gastrointestinal stromal tumor (GIST) with a KIT mutation.

Methods

Clinical, radiographic, and genetic data have been presented.

Results

A 40-year-old man with familial paraganglioma syndrome type 4 and recurrent paraganglioma presented with epigastric pain. He had undergone resection of a paraganglioma superior to the right adrenal gland at 19 years of age, resection of two para-aortic paragangliomas at 39 years, and resection of a paraganglioma in the interatrial septum at 40 years. Computed tomography scan showed a 3.2 × 3.8-cm gastric body intraluminal polypoid mass. A partial gastrectomy was performed, which revealed a GIST with a KIT mutation (NM_000222.2[KIT]:c.2466T>A[p.Asn822Lys]).

Conclusion

This case provides further evidence that mutations in SDHB and KIT are not mutually exclusive with GISTs. It also identifies the need for endoscopic evaluation for GIST in patients with familial paraganglioma syndrome type 4 with unexplained gastrointestinal symptoms.

Sarcoma Metabolomics: Current Horizons and Future Perspectives

The vast array of metabolic adaptations that cancer cells are capable of assuming, not only support their biosynthetic activity, but also fulfill their bioenergetic demands and keep their intracellular reduction-oxidation (redox) balance. Spotlight has recently been placed on the energy metabolism reprogramming strategies employed by cancer cells to proliferate. Knowledge regarding soft tissue and bone sarcomas metabolome is relatively sparse. Further characterization of sarcoma metabolic landscape may pave the way for diagnostic refinement and new therapeutic target identification, with benefit to sarcoma patients. This review covers the state-of-the-art knowledge on cancer metabolomics and explores in detail the most recent evidence on soft tissue and bone sarcoma metabolomics.

A Nomogram Predicting Progression Free Survival in Patients with Gastrointestinal Stromal Tumor Receiving Sunitinib: Incorporating Pre-Treatment and Post-Treatment Parameters

Simple Summary

Sunitinib has been approved as the second-line targeted treatment for gastrointestinal stromal tumor (GIST) after imatinib failure. It is thus necessary to effectively assess prognosis after sunitinib use. However, the current assessment remains insufficient for the contemporary period. We examined prognostic factors influencing progression-free survival. Furthermore, we constructed a prognostic nomogram model using these significant pre-treatment and post-treatment variables.

Abstract

The present study aimed to construct a prognostic nomogram incorporating pre-treatment and post-treatment factors to predict progression-free survival (PFS) after use of sunitinib in patients with metastatic gastrointestinal stromal tumors (GISTs) following imatinib intolerance or failure. From 2007 to 2018, 109 metastatic GIST patients receiving sunitinib at Chang Gung Memorial Hospital, Taiwan, were enrolled. A prognostic nomogram to predict PFS was developed. Sixty-three male and forty-six female metastatic GIST patients, with a median age of 61 years (range: 15–91 years), received sunitinib. The median PFS for 109 patients is 9.93 months. For pre-treatment factors, male gender, body mass index more than 18.5 kg/m², no sarcopenia status, higher lymphocyte count, lower platelet/lymphocyte ratio, good performance status, higher sunitinib dose, and non-liver metastasis were significantly associated with favorable PFS. For post-treatment factors, adverse events with hypertension, hand–foot skin reaction, and diarrhea were significantly associated with favorable PFS. However, only eight clinicopathological independent factors for PFS prediction were selected for prognostic nomogram establishment. The calibration curve for probability of PFS revealed good agreement between the nomogram prediction and actual observation. High risk patients will experience the lowest PFS. A prognostic nomogram integrating eight clinicopathological factors was constructed to assist prognostic prediction for individual patients with advanced GIST after sunitinib use.

Preoperative C-Reactive Protein/Albumin Ratio is a Prognostic Indicator for Survival in Surgically Treated Gastrointestinal Stromal Tumors: A Retrospective Cohort Study

Background

Systemic inflammation and malnutrition may promote tumor progression. C-reactive protein/albumin ratio (CAR) is linked to the poor long-term survival of several malignant tumors.

Purpose

To explore the predictive value of CAR in gastrointestinal stromal tumors (GISTs).

Methods

A retrospective study was conducted on 325 patients with primary GIST surgically treated with curative intent from 2009 to 2018. The cut-off point of CAR was set using X-tile software. Kaplan–Meier method and multivariate Cox regression model were used to study the prognostic value of CAR. The time-dependent receiver operating characteristic curve (tROC) was drawn, and the prognostic accuracy of CAR, Glasgow prognostic score (GPS), and National Institute of Health (NIH) risk classification was compared by the area under the curve (AUC).

Results

The best cut-off point of CAR was 0.55. Increased CAR was associated with the location of the lower digestive tract, larger tumor size, higher mitotic index, higher NIH risk classification, lower ALB, higher CRP, and higher GPS (all p<0.05). Multivariable analysis revealed that CAR (hazard ratio [HR] 2.598, 95% confidence interval [CI] 1.385–4.874; p=0.003) was an independent predictor of overall survival. Additionally, the AUC of CAR was lower than that of NIH risk classification at 2 years (0.601 vs. 0.775, p=0.002) and 5 years (0.629 vs 0.735, p=0.069). However, the AUC of NIH risk classification significantly increased (2-year OS 0.801, p=0.251; 5-year OS 0.777, p=0.011) when combined with CAR.

Conclusion

CAR is a new independent predictor of poor survival in patients with GIST. CAR combined with NIH risk classification can effectively improve the performance of prognosis prediction.

Spindle cell neoplasms of the upper gastrointestinal tract, hepatobiliary tract, and pancreas by fine needle aspiration: A single institutional experience of 15 years with follow-up data

BACKGROUND

The diagnosis of spindle cell neoplasms (SCN) of the upper gastrointestinal (GI) tract, hepatobiliary tract, and pancreas detected by fine needle aspiration (FNA) is challenging. We describe a single-center experience of these samples with follow-up data and characterization of the morphologic findings.

METHODS

We retrospectively reviewed pathology records for all FNAs diagnostic for or suggestive of SCN on esophagus, stomach, small bowel, liver, and pancreas in a 15 year period. All cases with at least 6 month follow-up were included. Surgical material (biopsy or resection) was the diagnostic gold standard. All FNAs with subsequent surgical specimens were reviewed and assessed for cellularity, architectural features, and nuclear features.

RESULTS

In 15 years, 5101 FNAs of the upper GI tract, hepatobiliary tract, and pancreas were performed. SCN was diagnosed in 98 (2%) patients. Seventy-two patients had definitive pathologic diagnoses: 68 were neoplastic and four were non-neoplastic. Cytomorphologic review in relationship to final diagnosis revealed three statistically significant features: low cellularity favors a benign process (P = .00544), epithelioid nuclear morphology favors malignancy (P = .00278), and identification of perinuclear vacuoles favors a diagnosis of GIST over non-GIST SCN (P = .04236).

CONCLUSIONS

Among cases with follow-up, final pathologic diagnoses were SCN in 94% of cases diagnosed as SCN on FNA of upper GI, hepatobiliary tract, and pancreas. Although some cytomorphologic criteria are more suggestive of malignancy, arriving at a specific diagnosis relies on collaboration of clinical, radiologic, cytomorphologic, and immunohistochemical data.

Gastric tumorigenesis after radical resection combined with adjuvant chemotherapy for colorectal cancer: two case reports and a literature review

Radical resection with or without adjuvant chemotherapy is a common option for stage II and III colorectal cancer. Few reports exist regarding gastric tumorigenesis, including gastric cancer, gastric intraepithelial neoplasia, and gastric stromal tumor, in patients who received this protocol as the standard treatment for colorectal cancer. We present two cases of gastric tumorigenesis in patients with colorectal cancer following radical resection combined with adjuvant chemotherapy. Both patients underwent gastrectomy and D2 lymphadenectomy for their gastric tumors; neither patient developed recurrence up to 2 years after treatment. These cases indicate that patients should be monitored closely for gastric tumorigenesis after treatment for colorectal cancer. Early detection and active surgical treatment can provide satisfactory results for colorectal cancer followed by gastric tumorigenesis. Long-term follow-up and regular examinations, especially gastroscopy, are necessary to detect gastric tumorigenesis after colorectal cancer. The focus on monitoring colorectal cancer alone in colorectal cancer patients should be changed to include a broader range of cancers in addition to precancers and other tumors, such as gastric stromal tumor.

Accessory spleen originating from the intrinsic muscularis of the stomach misdiagnosed as gastrointestinal stromal tumor: a case report

A 34-year-old man presented to our hospital with a 2-month history of repeated dull upper abdominal pain. Gastroscopy and endoscopic ultrasonography indicated a hemispherical mass at the junction of the greater curvature and the gastric fundus, with hypoechogenicity originating from the intrinsic muscular layer. He was diagnosed with a gastric body submucosal lesion and gastrointestinal stromal tumor, and underwent endoscopic full-thickness resection. However, postoperative pathological examination of the mass unexpectedly revealed heterotopic spleen tissue (accessory spleen). Intragastric ectopic spleen tissue originating from the intrinsic muscular layer of the stomach is a rare clinical condition, with no specific clinical symptoms. This finding is of great clinical significance for the identification of gastric submucosal tumors.

Gastric schwannoma: a case report and literature review

BACKGROUND

Gastric schwannoma is a rarely seen gastric tumor accounting for only 0.2% of all gastric tumors. It is difficult to distinguish a gastric schwannoma from other gastric tumors preoperatively.Case presentation: A 30-year-old man with no significant medical history or physical examination findings presented with a 1-month history of right upper abdominal discomfort. The preoperative diagnosis was a gastrointestinal stromal tumor, but the postoperative pathologic and immunohistochemical examinations confirmed a gastric schwannoma. The patient underwent laparoscopic wedge resection of the stomach without additional postoperative treatment, and his postoperative recovery was uneventful. No recurrence or metastasis was found at the 2-year follow-up examination.

CONCLUSION

Although gastric schwannomas are usually not malignant, they are difficult to distinguish from other malignant stromal tumors preoperatively. Surgical resection should be recommended when a schwannoma is malignant or considered to be at risk of becoming malignant.

Second Primary Tumors in Patients with Gastrointestinal Stromal Tumors: A Single-Center Experience

Background and Objectives: In this study, we investigated the frequency and type of second primary malignant tumors (SPMTs) accompanying gastrointestinal stromal tumors (GISTs), patient and tumor characteristics, and follow-up and survival data. Materials and Methods: We included 20 patients with SPMTs from a total of 103 patients with GISTs in a single center in Turkey. At the time of GIST diagnosis, patient age, sex, presentation symptoms, localization, pathological features of the tumor, stage, recurrence risk scoring for localized disease, treatments received, time of SPMT association, follow-up times, and survival analysis were recorded for each patient. Localization, histopathology, and stage of SPMT accompanying GISTs were also recorded accordingly. Results: SPMT was detected in 19.4% of patients with GISTs. Of the patients, 50% were men and 50% were women. The mean age at the time of diagnosis of GIST was 63.8 ± 10.81 years (range: 39–77 years). Of the GISTs, 60% were localized in the stomach, 25% in the small intestine, and 70% were at low risk. Of the SPMTs, 60% were in the gastrointestinal system. SPMTs were diagnosed as synchronous with GISTs in 50% of the patients. The mean follow-up period of the patients from the diagnosis of GIST was 45.6 (0.43–129.6) months. When the data were finalized, 5% died due to GIST, 35% died due to SPMT, and 15% died due to non-disease-related causes. Conclusions: SPMT was detected in 19.4% of patients with GISTs. GISTs were frequently located in the stomach, and most of them were at low risk. The most common SPMTs were gastrointestinal system tumors, and their coexistence was found to be synchronous. Most patients died due to SPMT during follow-up.

An updated review of the treatment landscape for advanced gastrointestinal stromal tumors

Before the introduction of tyrosine kinase inhibitors (TKIs), the overall survival of patients with advanced or metastatic gastrointestinal stromal tumors (GISTs) was 10 to 20 months because of the lack of approved therapies. In the last 20 years, a treatment algorithm for patients with advanced GISTs, which includes imatinib, sunitinib, and regorafenib as first‐, second‐, and third‐line therapies, respectively, has been established. Recently, 2 new TKIs have been approved: ripretinib for fourth‐line therapy and avapritinib as first‐line therapy in patients harboring platelet‐derived growth factor receptor α (PDGFRA) exon 18 D842V mutations. Additionally, there are several experimental therapies under investigation that could advance individualized patient care. All of these therapies have varying efficacies and safety profiles that warrant an updated treatment landscape review. This review article summarizes the efficacy and safety data currently available for conventional TKIs along with recently approved and experimental therapies.

With evolving treatment options and effective toxicity management, patients with advanced gastrointestinal stromal tumors are living longer than ever before. Recently approved targeted therapies and the investigation of experimental treatment options have the potential to alter the current treatment algorithm and encourage personalized patient care.

Intragastric Single-Port Surgery: An Innovative and Multipurpose Technique for the Therapy of Upper Digestive Tract Lesions

Background: Endoscopic treatment can represent a technical challenge for several special situations, such as resecting gastric tumors with larger size or in unfavorable sites and performing endoscopic retrograde cholangiopancreatography (ERCP) after Roux-en-Y gastric bypass (RYGB). This study aims to describe an innovative and multipurpose technique, intragastric single-port surgery (IGS), which can be applied for abovementioned special situations and for assessing its safety, feasibility, and efficacy. Methods: IGS technique was performed through a 2-3 cm skin incision, where the stomach wall is exteriorized and fixed to the skin. The single-port device is inserted and intragastric access is gained for laparoscopic or endoscopic instruments. Three purposes of IGS were performed: (1). gastric intraluminal lesions resection; (2). to perform ERCP after RYGB; and (3). revision of pancreaticogastric anastomosis after pylorus-preserving pancreaticoduodenectomy. Results: IGS was performed successfully in 20 patients. Ten patients underwent gastric intraluminal lesion resection, mostly for gastric gastrointestinal stromal tumors (n = 7, 70%); all pathological specimens were with negative margin, mean operation time was 102.3 ± 43.5 minutes, and mean postoperative hospital stay was 4.6 ± 1.5 days. Nine patients underwent ERCP after RYGB, cleaning of the bile duct was successful in all patients (100%), and mean operation time and mean postoperative hospital stay were 140.6 ± 46.3 minutes and 4.4 ± 2.6 days, respectively. One patient underwent pancreaticogastric anastomosis revision. There were no mortalities in our series. Conclusions: IGS is a safe, feasible, and effective technique for gastric intraluminal lesion resection and for performing ERCP after RYGB, while it has the potential for other future applications.

Computed-Tomography-Based Radiomics Model for Predicting the Malignant Potential of Gastrointestinal Stromal Tumors Preoperatively: A Multi-Classifier and Multicenter Study

Background: Our goal was to establish and verify a radiomics risk grading model for gastrointestinal stromal tumors (GISTs) and to identify the optimal algorithm for risk stratification. Methods: We conducted a retrospective analysis of 324 patients with GISTs, the presence of which was confirmed by surgical pathology. Patients were treated at three different hospitals. A training cohort of 180 patients was collected from the largest center, while an external validation cohort of 144 patients was collected from the other two centers. To extract radiomics features, regions of interest (ROIs) were outlined layer by layer along the edge of the tumor contour on CT images of the arterial and portal venous phases. The dimensionality of radiomic features was reduced, and the top 10 features with importance value above 5 were selected before modeling. The training cohort used three classifiers [logistic regression, support vector machine (SVM), and random forest] to establish three GIST risk stratification prediction models. The receiver operating characteristic curve (ROC) was used to compare model performance, which was validated by external data. Results: In the training cohort, the average area under the curve (AUC) was 0.84 ± 0.07 of the logistic regression, 0.88 ± 0.06 of the random forest, and 0.81 ± 0.08 of the SVM. In the external validation cohort, the AUC was 0.85 of the logistic regression, 0.90 of the random forest, and 0.80 of the SVM. The random forest model performed the best in both the training and the external validation cohorts and could be generalized. Conclusion: Based on CT radiomics, there are multiple machine-learning models that can predict the risk of GISTs. Among them, the random forest algorithm had the highest prediction efficiency and could be readily generalizable. Through external validation data, we assume that the random forest model may be used as an effective tool to guide preoperative clinical decision-making.

Differential Expression of CADM1 in Gastrointestinal Stromal Tumors of Different Sites and with Different Gene Abnormalities

Gastrointestinal stromal tumor (GIST), the most common mesenchymal tumor of the human gastrointestinal tract, differentiating toward the interstitial cell of Cajal (ICC), arises predominantly in the stomach and small intestine. Small intestinal GISTs appear to have worse prognosis than gastric GISTs. In a pilot study of a cDNA expression chip using several GISTs, we found that Cell Adhesion Molecule 1 (CADM1), which could contribute to tumor growth and infiltration, is expressed more strongly in small intestinal GISTs than gastric GISTs. In the present study, we examined CADM1 expression in GISTs of different sites and with different gene abnormalities using a large number of gastric and small intestinal GISTs. First, immunoblotting confirmed significantly higher CADM1 expression in small intestinal GISTs with exon 11 c-kit mutation than gastric GISTs with exon 11 c-kit mutation. Real-time PCR also revealed that small intestinal GISTs with exon 11 c-kit mutation showed significantly higher CADM1 mRNA than gastric GISTs with exon 11 c-kit mutation. Although most small intestinal GISTs showed high CADM1 mRNA expression regardless of gene abnormality types, different CADM1 expression was detected between gastric GISTs with c-kit mutation and those with PDGFRA mutation. Immunohistochemistry showed that many small intestinal GISTs were CADM1-positive but most gastric GISTs CADM1-negative or -indefinite. In the normal gastric and small intestinal walls, immunoreactivity of CADM1 was detected only in nerves, but neither in gastric ICCs nor small intestinal ICCs, indicating that the high CADM1expression in small intestinal GISTs might be acquired during tumorigenesis. Different CADM1 expression between gastric and small intestinal GISTs might be related to different prognoses between them. Further functional experiments are needed to elucidate the role of CADM1 on GIST biology, and there is a possibility that targeting therapy against CADM1 has a preventive effect for tumor spreading in small intestinal GISTs.

Preoperative imaging of gastric GISTs underestimates pathologic tumor size: A retrospective, single institution analysis

BACKGROUND

How well imaging size agrees with pathologic size of gastric gastrointestinal stromal tumors (GISTs) is unknown. GIST risk stratification is based on pathologic size, location, and mitotic rate. To inform decision making, the size discrepancy between imaging and pathology for gastric GISTs was investigated.

METHODS

Imaging and pathology reports were reviewed for 113 patients. Bland-Altman analyses and intraclass correlation (ICC) assessed agreement of imaging and pathology. Changes in clinical risk category due to size discrepancy were identified.

RESULTS

Computed tomography (CT) (n = 110) and endoscopic ultrasound (EUS) (n = 50) underestimated pathologic size for gastric GISTs by 0.42 cm, 95% confidence interval (CI): (0.11, 0.73), p = 0.008 and 0.54 cm, 95% CI: (0.25, 0.82), p < 0.001, respectively. ICCs were 0.94 and 0.88 for CT and EUS, respectively. For GISTs ≤ 3 cm, size underestimation was 0.24 cm for CT (n = 28), 95% CI: (0.01, 0.47), p = 0.039 and 0.56 cm for EUS (n = 26), 95% CI: (0.27, 0.84), p < 0.0001. ICCs were 0.72 and 0.55 for CT and EUS, respectively. Spearman's correlation was ≥0.84 for all groups. For GISTs ≤ 3 cm, 6/28 (21.4% p = 0.01) on CT and 7/26 (26.9% p = 0.005) on EUS upgraded risk category using pathologic size versus imaging size. No GISTs ≤ 3 cm downgraded risk categories. Size underestimation persisted for GISTs ≤ 2 cm on EUS (0.39 cm, 95% CI: [0.06, 0.72], p = 0.02, post hoc analysis).

CONCLUSION

Imaging, particularly EUS, underestimates gastric GIST size. Caution should be exercised using imaging alone to risk-stratify gastric GISTs, and to decide between surveillance versus surgery.

Ripretinib for the treatment of advanced gastrointestinal stromal tumor

Gastrointestinal stromal tumors (GISTs) are rare tumors of the gastrointestinal (GI) tract yet represent the most common GI sarcomas. Most GISTs are driven by activating mutations of the KIT and/or PDGFRA genes. Prior to the development of tyrosine kinase inhibitors (TKIs), GISTs were associated with a poor prognosis because conventional cytotoxic chemotherapy was relatively ineffective. However, TKIs that inhibit the most common driver mutations in KIT or PDGFRA have revolutionized the treatment of GISTs over the past two decades. Notwithstanding, ongoing management challenges relate to the development of secondary mutations in these genes, resulting in tumor progression. Due to both the intra- and inter-patient heterogeneity of these secondary mutations in GISTs, optimal treatment requires an agent that blocks as many mutant genes as possible. Ripretinib - a novel switch-control TKI - inhibits many of the most common primary and secondary activating KIT and PDGFRA mutants involved in GIST progression through a dual mechanism of action. In the pivotal INVICTUS phase III trial, patients with advanced GIST that had progressed on at least imatinib, sunitinib, and regorafenib and who received ripretinib experienced significantly longer progression-free survival (primary endpoint) as well as prolongation of overall survival, compared with those receiving placebo. Treatment with ripretinib was associated with durable improvements in quality-of-life indices and a manageable toxicity profile. The most frequent side effects were common to the class of TKIs used in the management of GIST. These results led to the approval of ripretinib for treatment of advanced GIST in adults who have received three or more TKIs, including imatinib. Ripretinib is also under investigation in the second-line treatment of advanced GIST in a phase III trial (INTRIGUE) comparing ripretinib with sunitinib in patients with advanced GIST after treatment with imatinib.

PLAIN LANGUAGE SUMMARY

Use of ripretinib for the treatment of gastrointestinal stromal tumors (GISTs) Gastrointestinal stromal tumors (GISTs) are a rare type of tumor most commonly located in the stomach and small intestine but can develop anywhere throughout the gastrointestinal tract. The symptoms of GISTs vary in extent depending on location of the primary tumor and include a feeling of fullness, abdominal pain, intestinal bleeding, and fatigue. Since these symptoms are nonspecific, making a diagnosis can be challenging. Most GISTs carry initial mutations in genes that control specific enzymes called tyrosine kinases. Historically, treatment of GISTs was limited because traditional chemotherapy is ineffective against these tumors. However, with the introduction of drugs that inhibit tyrosine kinases [i.e., tyrosine kinase inhibitors (TKIs)], survival has been extended substantially. However, many GISTs go on to develop secondary mutations that render them resistant to a given TKI. Prior to the approval of ripretinib, four TKIs were available for the treatment of GIST: imatinib; sunitinib; regorafenib; and, recently, avapritinib. Each drug is used until resistance develops or patients are unable to tolerate the side effects of treatment, after which the next drug is started. Ripretinib was recently approved by the FDA as the fourth drug in the usual treatment sequence recommended for patients with advanced GIST who have progressed (or are treatment intolerant) after receiving three or more TKIs, including imatinib. Approval of ripretinib was based on the results of the INVICTUS trial, which demonstrated that the drug significantly improves the time patients have without progression of the disease or death compared with placebo. The most common side effects related to ripretinib were hair loss, muscle pain, nausea, fatigue, hand-foot syndrome, and diarrhea, although most events were not very severe. Ripretinib is being further studied as the second TKI used in patients with GIST who have progressed on or could not tolerate first-line treatment with imatinib.

Discovery of novel potential KIT inhibitors for the treatment of gastrointestinal stromal tumor

Numerous inhibitors of tyrosine-protein kinase KIT, a receptor tyrosine kinase, have been explored as a viable therapy for the treatment of gastrointestinal stromal tumor (GIST). However, drug resistance due to acquired mutations in KIT makes these drugs almost useless. The present study was designed to screen the novel inhibitors against the activity of the KIT mutants through pharmacophore modeling and molecular docking. The best two pharmacophore models were established using the KIT mutants’ crystal complexes and were used to screen the new compounds with possible KIT inhibitory activity against both activation loop and ATP-binding mutants. As a result, two compounds were identified as potential candidates from the virtual screening, which satisfied the potential binding capabilities, molecular modeling characteristics, and predicted absorption, distribution, metabolism, excretion, toxicity (ADMET) properties. Further molecular docking simulations showed that two compounds made strong hydrogen bond interaction with different KIT mutant proteins. Our results indicated that pharmacophore models based on the receptor–ligand complex had excellent ability to screen KIT inhibitors, and two compounds may have the potential to develop further as the future KIT inhibitors for GIST treatment.

Improved understanding of gastrointestinal stromal tumors biology as a step for developing new diagnostic and therapeutic schemes

A gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the human gastrointestinal tract, with an estimated incidence of 10-15 per 1 million per year. While preparing holistic care for patients with GIST diagnosis, scientists might face several difficulties - insufficient risk stratification, acquired or secondary resistance to imatinib, or the need for an exceptional therapy method associated with wild-type tumors. This review summarizes recent advances associated with GIST biology that might enhance diagnostic and therapeutic strategies. New molecules might be incorporated into risk stratification schemes due to their proven association with outcomes; however, further research is required. Therapies based on the significant role of angiogenesis, immunology, and neural origin in the GIST biology could become a valuable enhancement of currently implemented treatment schemes. Generating miRNA networks that would predict miRNA regulatory functions is a promising approach that might help in better selection of potential biomarkers and therapeutical targets in cancer, including GISTs.

Case Report: Totally Laparoscopic Resection of Retroperitoneal Paraganglioma Masquerading as a Duodenal Gastrointestinal Stromal Tumor

Introduction: Retroperitoneal paraganglioma (RPGL) is a rare clinical tumor derived from the retroperitoneal sympathetic paraganglion tissue. Since RPGLs are locate deeply and have no specific symptoms and imaging manifestations at the early stage, which easily causes missed diagnosis or misdiagnosis. In addition, reports on totally laparoscopic resection of RPGLs are scarce due to their close proximity to large vessels, giant size, uncertain location, and unknown malignant status.

Case Presentation: We present here the case of totally laparoscopic resection of a 6.4 × 5.4 cm RPGL that was discovered during a workup for discomfort and upper abdominal pain in a 68-year-old female patient, mimicking a gastrointestinal stromal tumor (GIST) of the duodenum, Which was confirmed as a RPGL based on the histopathological and immunohistochemical findings.

Conclusions: RPGL is a rare tumor, and the transperitoneal laparoscopic approach for the RPGL is a safe, applicable method with less trauma and quick recovery, which is worth clinical popularizing and application. Moreover, the survival prognosis of RPGL patients are related to metastasis, and lifelong follow-up should be emphasized.

Gene Expression Landscape of SDH-Deficient Gastrointestinal Stromal Tumors

BACKGROUND

About 20-40% of gastrointestinal stromal tumors (GISTs) lacking KIT/PDGFRA mutations show defects in succinate dehydrogenase (SDH) complex. This study uncovers the gene expression profile (GEP) of SDH-deficient GIST in order to identify new signaling pathways or molecular events actionable for a tailored therapy.

METHODS

We analyzed 36 GIST tumor samples, either from formalin-fixed, paraffin-embedded by microarray or from fresh frozen tissue by RNA-seq, retrospectively collected among KIT-mutant and SDH-deficient GISTs. Pathway analysis was performed to highlight enriched and depleted transcriptional signatures. Tumor microenvironment and immune profile were also evaluated.

RESULTS

SDH-deficient GISTs showed a distinct GEP with respect to KIT-mutant GISTs. In particular, SDH-deficient GISTs were characterized by an increased expression of neural markers and by the activation of fibroblast growth factor receptor signaling and several biological pathways related to invasion and tumor progression. Among them, hypoxia and epithelial-to-mesenchymal transition emerged as features shared with SDH-deficient pheochromocytoma/paraganglioma. In addition, the study of immune landscape revealed the depletion of tumor microenvironment and inflammation gene signatures.

CONCLUSIONS

This study provides an update of GEP in SDH-deficient GISTs, highlighting differences and similarities compared to KIT-mutant GISTs and to other neoplasm carrying the SDH loss of function. Our findings add a piece of knowledge in SDH-deficient GISTs, shedding light on their putative histology and on the dysregulated biological processes as targets of new therapeutic strategies.

Ruptured Small Intestinal Stromal Tumor Causing Concurrent Gastrointestinal and Intra-Abdominal Hemorrhage: A Case Report

Gastrointestinal stromal tumors (GISTs) originate from mesenchymal cells throughout the gastrointestinal tract. A common symptom is gastrointestinal hemorrhage; intra-abdominal hemorrhage is relatively rare. There are few reports of GIST presenting with both types of hemorrhage concurrently. A 77-year-old man was admitted to our hospital because of melena and anemia (Hb: 4.7 g/dL). Computed tomography revealed a small bowel tumor and high-density fluid in both the small intestine and the pelvic floor. We diagnosed a small intestinal tumor with concurrent gastrointestinal and intra-abdominal hemorrhage, and performed emergency surgery. The tumor arose from the small intestine and was ruptured. We found hemorrhage in the pelvic cavity and performed partial small intestine resection. Pathological findings revealed that the tumor was positive for c-Kit protein and was diagnosed as GIST. The patient was discharged from the hospital on postoperative day 9 and received imatinib 1 month postoperatively. We experienced a very rare case of ruptured GIST originating from the small intestine associated with both gastrointestinal and intra-abdominal hemorrhage. We also reviewed the relevant literature.

Disseminated Mycobacterium avium Intracellulare Infection With Concurrent Small Bowel Obstruction: Case, Pathophysiology, and Clinical Considerations

Mycobacterium avium intracellulare (MAI) is an opportunistic infection that typically manifests itself as pulmonary infection. In immunocompromised patients, however, MAI can uncommonly cause disseminated disease and diffuse gastrointestinal involvement. Small bowel obstruction with concurrent MAI infection is rarely documented in literature. Here, a 60-year-old female with a past medical history significant for a gastrointestinal stromal tumor, two small bowel obstructions, and a bowel perforation repair presented to the emergency department with sharp abdominal pain due to a small bowel obstruction. Cultures obtained from the laparoscopic release of small bowel obstruction confirmed the presence of MAI. An antibiotic course of ethambutol, azithromycin, and rifampin was initiated and continued upon transfer to a long-term acute care facility. We describe this case to highlight the possibility of MAI infection in patients with postoperative abdominal pain resulting from small bowel obstruction, review the underlying pathophysiology, and discuss its epidemiology.

Rare Occurrence of Microsatellite Instability in Gastrointestinal Stromal Tumors

Background and Objectives: This study aimed to objectively determine microsatellite instability (MSI) status using a next-generation sequencing (NGS)-based MSI panel and to resolve the discrepancy regarding whether or not MSI is a rare phenomenon, irrespective of diverse genomic alterations in gastrointestinal stromal tumors (GISTs). Materials and Methods: Genomic DNA was subjected to MSI panel sequencing using an Ion AmpliSeq Microsatellite Instability Assay, as well as to cancer gene panel sequencing using an Oncomine Focus DNA Assay. Results: All of our GIST patients showed microsatellite-stable (MSS) status, which confirmed that MSI status did not affect the molecular pathogenesis of GIST. The KIT gene (79%, 38/48) was the most frequently mutated gene, followed by the PDGFRA (8%, 4/48), PIK3CA (8%, 4/48), and ERBB2 (4%, 2/48) mutations. KIT exon 11 mutant patients were more favorable in responding to imatinib than those with exon 9 mutant or wild-type GISTs, and compared to non-KIT exon 11 mutant GISTs (p = 0.041). The NGS-based MSI panel with MSICall confirmed a rare phenomenon of microsatellite instability in GISTs irrespective of diverse genomic alterations. Conclusion: Massively parallel sequencing can simultaneously provide the MSI status as well as the somatic mutation profile in a single test. This combined approach may help us to understand the molecular pathogenesis of GIST carcinogenesis and malignant progression.

Different Medical Features and Strategies of Large Rectal Gastrointestinal Stromal Tumor: A Multi-Central Pooling Analysis

Purpose

The rectum is a rare site for gastrointestinal stromal tumors (GISTs). Tumors in this critical anatomical site are prone to develop local recurrence, and this occurs at a high level even in low-risk tumors. Previous studies found that high-risk was the most common category in rectal gastrointestinal stromal tumors (RGISTs), and size was the most important factor affecting the long-term prognosis. We aimed to find out the most influential factor on clinical outcomes, and describe demographics, oncological differences, and surgical procedures in patients with poor prognosis.

Patients and Methods

Data on consecutive patients with RGIST, who were diagnosed at Peking University People’s Hospital, Shandong Province Hospital, and The First Affiliated Hospital of Shandong First Medical University from 2010 to 2020, were retrospectively evaluated. Further, a literature search was conducted by retrieving data from PubMed, EMBASE, and the Cochrane Library databases from inception up to March 20, 2020.

Results

In all, 50 patients were diagnosed with RGIST at three medical centers, and 86 published records were finally included in the literature review. Combined analysis of the whole individual patient data showed that 5.5 cm was deemed an appropriate cut-off value for L-RGIST, and that patients usually showed a male predominance (67.59%), younger age at onset (56.61 years), higher operative difficulty, and poorer prognosis.

Conclusion

Separation of patients with large RGIST from general patients may contribute to the recognition of the oncological characteristics and clinical management of this rare type of tumor.

The Identity of PDGFRA D842V-Mutant Gastrointestinal Stromal Tumors (GIST)

Simple Summary

Among the platelet-derived growth factor receptor (PDGFRA) mutations in gastrointestinal stromal tumors (GIST), the most frequent is the substitution at position 842 in the A-loop of an aspartic acid (D) with a valine (V), widely recognized as D842V, a two-sided mutation providing primary resistance to all currently approved agents for GIST treatment. In recent years, new specific inhibitors have been studied in preclinical and clinical settings, and molecular findings have been accumulated, well describing this complex entity. This paper aims at offering a comprehensive picture of the clinical features and the molecular background of this rare subtype of GIST.

Abstract

The majority of gastrointestinal stromal tumors (GIST) carry a sensitive primary KIT mutation, but approximately 5% to 10% of cases harbor activating mutations of platelet-derived growth factor receptor (PDGFRA), mainly involving the A-loop encoded by exon 18 (~5%), or more rarely the JM domain, encoded by exon 12 (~1%), or the ATP binding domain encoded by exon 14 (<1%). The most frequent mutation is the substitution at position 842 in the A-loop of an aspartic acid (D) with a valine (V) in exon 18, widely recognized as D842V. This mutation, as well known, provides primary resistance to imatinib and sunitinib. Thus, until few years ago, no active drugs were available for this subtype of GIST. Conversely, recent years have witnessed the development of a new specific inhibitor—avapritinib—that has been studied in in vitro and clinical setting with promising results. In light of this primary resistance to conventional therapies, the biological background of D842V-mutant GIST has been deeply investigated to better understand what features characterize this peculiar subset of GIST, and some promising insights have emerged. Hereinafter, we present a comprehensive overview on the clinical features and the molecular background of this rare subtype of GIST.

Preservation of Organ Function in Locally Advanced Non-Metastatic Gastrointestinal Stromal Tumors (GIST) of the Stomach by Neoadjuvant Imatinib Therapy

Simple Summary

This study reports a single-center analysis of 55 patients with primary, locally advanced gastric GIST treated with imatinib mesylate (IM) preoperatively for a median of 10 months. The therapy yielded shrinkage of median tumor size from 113 mm to 62 mm. This facilitated 50 patients to undergo significantly less-extensive surgical procedures and resulted in a stomach preservation rate of 96%. The rate of R0 resections was 94% and was followed by a mean recurrence-free-survival time of 132 months with the median not reached. The approach was successful even for patients starting IM during an episode of upper gastrointestinal bleeding. Neoadjuvant IM therapy for locally advanced, non-metastatic gastrointestinal stromal tumors (GIST) of the stomach may play an important role in preserving organ function which might be important for IM plasma levels in an adjuvant or metastatic setting.

Abstract

Background: Neoadjuvant imatinib mesylate (IM) for advanced, non-metastatic gastrointestinal stromal tumors (GIST) of stomach is recommended to downsize the tumor prompting less-extensive operations and preservation of organ function. Methods: We analyzed the clinical-histopathological profile and oncological outcome of 55 patients (median age 58.2 years; range, 30–86 years) with biopsy-proven, cM0, gastric GIST who underwent IM therapy followed by surgery with a median follow-up of 82 months. Results: Initial median tumor size was 113 mm (range, 65–330 mm) and 10 patients started with acute upper GI bleeding. After a median 10 months (range, 2–21 months) of treatment, tumor size had shrunk to 62 mm (range, 22–200 mm). According to Response Evaluation Criteria In Solid Tumors version 1.0 and version 1.1 (RECIST 1.1), 39 (75%) patients had partial response and 14 patients had stable disease, with no progressive disease. At plateau response, 50 patients underwent surgery with an R0 resection rate of 94% and pathological complete response in 24%. In 12 cases (24%), downstaging allowed laparoscopic resection. The mean recurrence-free survival (RFS) was 123 months (95%CI; 99–147) and the estimated 5-year RFS was 84%. Conclusions: Neoadjuvant IM allowed stomach preservation in 96% of our patients with excellent long-term RFS, even when starting treatment during an episode of upper GI bleeding. Preservation of the stomach provides the physiological basis for the use of oral IM in the adjuvant or metastatic setting.

Epidemiology, Diagnosis, Staging and Multimodal Therapy of Esophageal and Gastric Tumors

Gastric and esophageal tumors are diverse neoplasms that involve mucosal and submucosal tissue layers and include squamous cell carcinomas, adenocarcinomas, spindle cell neoplasms, neuroendocrine tumors, marginal B cell lymphomas, along with less common tumors. The worldwide burden of esophageal and gastric malignancies is significant, with esophageal and gastric cancer representing the ninth and fifth most common cancers, respectively. The approach to diagnosis and staging of these lesions is multimodal and includes a combination of gastrointestinal endoscopy, endoscopic ultrasound, and cross-sectional imaging. Likewise, therapy is multidisciplinary and combines therapeutic endoscopy, surgery, radiotherapy, and systemic chemotherapeutic tools. Future directions for diagnosis of esophageal and gastric malignancies are evolving rapidly and will involve advances in endoscopic and endosonographic techniques including tethered capsules, optical coherence tomography, along with targeted cytologic and serological analyses.

Laparoscopic RouxenY gastric bypass in Type 2 diabetes mellitus patient with low body mass index and gastric stromal tumor: A case report

Laparoscopic Roux-en-Y gastric bypass (LRYGB) has been proved to be a safe and effective treatment for Type 2 diabetes mellitus (T2DM) patients with body mass index (BMI) >27.5 kg/m2 in China. The incidence of gastrointestinal stromal tumor (GIST) is very low, whereas the relevant studies on GIST and LRYGB are few. This is the first report of GIST associated with LRYGB in low BMI Chinese patient with T2DM.A male patient with GIST and T2DM, whose body weight and height were 67 kg and 175 cm, respectively,and the calculated BMI was 21.9 kg/m2. He was diagnosed by gastroscopy and enhanced CT scan. We used LRYGB to treat GIST and T2DM at the same time. After the operation, the GIST was removed successfully. Both the blood glucose levels and glycosylated hemoglobin were normal at 4 months and 1 year later. The patient received follow-up gastroscopy and abdominal CT scan and did not find out local recurrence and metastasis. LRYGB may be the best choice in treating GIST in T2DM with low BMI.

Single-cell transcriptome analysis revealed the heterogeneity and microenvironment of gastrointestinal stromal tumors

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the human gastrointestinal tract. In this study, we performed single-cell RNA sequencing (RNA-seq) on intra- and peri-tumor tissues from GIST patients with the aim of discovering the heterogeneity of tumor cells in GIST and their interactions with other cells. We found four predominating cell types in GIST tumor tissue, including T cells, macrophages, tumor cells, and NK cells. Tumor cells could be clustered into two groups: one was highly proliferating and associated with high risk of metastasis, the other seemed "resting" and associated with low risk. Their clinical relevance and prognostic values were confirmed by RNA-seq of 65 GIST samples. T cells were the largest cell type in our single-cell data. Two groups of CD8⁺ effector memory (EM) cells were in the highest clonal expansion and performed the highest cytotoxicity but were also the most exhausted among all T cells. A group of macrophages were found polarized to possess both M1 and M2 signatures, and increased along with tumor progression. Cell-to-cell interaction analysis revealed that adipose endothelial cells had high interactions with tumor cells to facilitate their progression. Macrophages were at the center of the tumor microenvironment, recruiting immune cells to the tumor site and having most interactions with both tumor and nontumor cells. In conclusion, we obtained an overview of the GIST microenvironment and revealed the heterogeneity of each cell type and their relevance to risk classifications, which provided a novel theoretical basis for learning and curing GISTs.

Targeted Deep Sequencing Reveals Unrecognized KIT Mutation Coexistent with NF1 Deficiency in GISTs

Purpose

NF1-deficient GISTs account for about 1% of gastrointestinal stromal tumors (GISTs) and are usually considered as a subtype of KIT/PDGFRA wild-type GISTs that have no detectable KIT and PDGFRA mutations. Some KIT/PDGFRA wild-type GISTs actually have cryptic KIT mutations (mKIT). So we investigate whether concurrent mKIT existed in NF1-associated GISTs.

Patients and Methods

Three independent cohorts were retrospectively analyzed. KIT/PDGFRA wild-type GISTs in Xiangya Hospital between May 2017 and Oct 2019 were investigated by next-generation sequencing (NGS) approach targeted 1021 cancer-related genes regions. GISTs cases in Gene+ dataset from May 2017 to May 2020 were collected from the platform of this company. The genotypes of GISTs in MSKCC cohort were downloaded from cBioPortal.

Results

A total of 290 cases including 23 KIT/PDGFRA wild-type GISTs in Xiangya Hospital, 136 GISTs in Gene+ database, and 131 GISTs in MSKCC were enrolled. Twenty-six cases have NF1 mutations (mNF1), and 48% (12/26) of NF1-mutated GISTs have concurrent mKIT. Compared with MSKCC (2/10, 20%), a higher ratio of mKIT in NF1-associated GISTs was detected in Xiangya Hospital (3/5, 60%) and Gene+ (7/11, 64%) (p<0.05). No mutation hotspot existed in mNF1. Most of mKIT centered within exon 11 (7/12, 58%) and others including exon 17 (3/12, 25%), exon 9(1/12, 8%), exon 13 (1/12, 8%) and exon 21 (1/12, 8%). No differences in age, gender, and location were detected between NF1-related GISTs with mKIT and those without mKIT. Three GIST cases of type I neurofibromatosis, skin neurofibromas and micro-GISTs (≤1 cm) were devoid of mKIT, but all the mini-GISTs (1~2 cm) and clinic GIST lesions (>2 cm) in two cases harbored mKIT.

Conclusion

mKIT was not unusual in NF1-associated GISTs, especially in Chinese populations. The gain-of-function mKIT possibly facilitated the progression of NF1-deficient lesions to clinic GISTs, however, the underlying mechanism warrants further studies.

Ripretinib in gastrointestinal stromal tumor: the long-awaited step forward

Gastrointestinal stromal tumor (GIST) represents a paradigm for clinically effective targeted inhibition of oncogenic driver mutations in cancer. Five drugs are currently positioned as the standard of care for the treatment of advanced or metastatic GIST patients. This is the result of continuous, deep understanding of KIT and PDGFRA GIST oncogenic drivers as well as the resistance mechanisms associated to tumor progression. However, the complexity of GIST molecular heterogeneity is an evolving field, and critical questions remain open. Specifically, the clinical benefit of approved and/or investigated targeted agents is strikingly modest at advanced stages of the disease when compared with the activity of first-line imatinib. Ripretinib is a novel switch-pocket inhibitor with broad activity against KIT and PDGFRA oncoproteins and has recently demonstrated antitumoral activity across phase I to phase III clinical trials. Therefore, ripretinib has emerged as a new standard of care for advanced, multi-resistant GIST patients. Based on this data, the Food and Drug Administration has granted in 2020 the approval of ripretinib for GIST patients after progression to imatinib, sunitinib and regorafenib. This, in turn, constitutes a major breakthrough in sarcoma drug development, as there have not been new treatment approvals in GIST for nearly a decade. Herein, we provide a critical review on the preclinical and clinical development of ripretinib in GIST. Furthermore, we seek to assess the biological and clinical impact of this new standard of care on the course of the disease, aiming to provide an insight on future treatments strategies for the next coming years.

Gastrointestinal stromal tumors of the colon and rectum

Gastrointestinal stromal tumors (GISTs) are rare neoplasms, colorectal location being met in less than 5% of cases. Knowledge about this site related particularities are limited. The aim of this study is to present our experience with colorectal GISTs between 2005 and 2018 from the clinical, morphological, and immunohistochemical perspectives, with emphasis on prognostic factors. From a total of 203 gastrointestinal stromal tumors registered, 12 were colorectal (6%). The number of colonic tumors surpassed that of the rectum (9 : 3) and on the right side were registered more cases than on the left side (6/3). 9 were primary tumors and 3 were recurrences. Men and women were represented equally and the age range was between 22 and 76. Tumor dimensions varied between 0.5 and 14 cm. Microscopically, spindle cell type was dominant. Mitotic rate was variable between 1 and 115/50HPFs. Accordingly, for primary tumors progression risks were assigned (low risk: 2 cases, intermediate risk: 3 cases and high risk: 4 cases). All GISTs were CD117 and DOG1 positive. Four of the patients died of the disease.

Rare cause of cystic liver lesions: Liver metastasis of gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are rare mesenchymal neoplasms of the gastrointestinal tract with an annual incidence of 1–2 per 10 000 people. Although most GISTs are solid, they may present with predominantly cystic components. A 69‐year‐old Japanese woman presented with a recently elevated gamma‐glutamyl transpeptidase level. Computed tomography revealed multiple space‐occupying lesions (SOLs) in the liver. These SOLs appear cystic on magnetic resonance imaging and abdominal ultrasound and are associated with thick walls at the margins. In addition, these thick walls showed high intensity on diffusion‐weighted images. She was diagnosed with liver metastasis of GIST by diagnostic biopsies from the thick parts of the cystic liver lesion (thick walls at the margins). The primary lesion was thought to be located along the medial side of the descending part of the duodenum, but a duodenal biopsy was initially undiagnosed. Liver metastases due to GISTs are known to cause cystic changes after treatment, such as imatinib mesylate. However, to the best of our knowledge, only six cases where hepatic GIST with predominantly cystic changes (prior to any treatment) have been reported. It should be noted that GISTs appear cystic in all organs.

Assessment of Adherence to Imatinib and Health-Related Quality of Life Among Patients with Gastrointestinal Stromal Tumor: A Cross-Sectional Study in an Oncology Clinic in Malaysia

PURPOSE

To evaluate the rate and predictors of non-adherence to imatinib in gastrointestinal stromal tumor (GIST) patients, as well as to compare the difference in health-related quality of life (HRQOL) between adherent and non-adherent patients.

PATIENTS AND METHODS

A cross-sectional study at the Oncology Clinic, Hospital Kuala Lumpur was conducted from March to August 2018. All patients with metastatic and/or unresectable GIST aged ≥18 years old and on at least 3 months of imatinib were included. Adherence to imatinib was assessed using the 10-item validated Medication Compliance Questionnaire, with a score of <100% indicating non-adherence. Non-adherence predictors were determined by multiple logistic regressions. HRQOL was evaluated by the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30). The difference in the mean HRQOL scores between adherent and non-adherent groups was determined by multivariate analysis of variance.

RESULTS

A total of 89 patients were enrolled, of which 49 (55.1%) were considered non-adherent. The significant predictors of non-adherence were age (adjusted odds ratio [OR] 0.93; CI 0.89-0.98; P = 0.007), presence of nausea and vomiting (OR 5.63; CI 1.25-25.27; P = 0.024), and presence of comorbidities (OR 4.56; CI 1.44-14.40; P = 0.010). Patients who were in the adherent group showed significantly better score in overall HRQOL, F (15, 73) = 2.09, P < 0.02; Pillai's trace = 0.3, partial eta squared = 0.30.

CONCLUSION

Non-adherence to long-term treatment with imatinib among patients with GIST should not be underestimated. Significant predictors of non-adherence among this population are younger age, presence of nausea and vomiting, as well as comorbidities. Patients with good adherence portrayed better HRQOL.

Reduced-port surgery with the cowboy technique for a gastric submucosal tumor

INTRODUCTION

Laparoscopic surgery is considered safe and effective for a gastric submucosal tumors, and reduced-port surgery (RPS) is being increasingly performed to treat these tumors. Herein, we present laparoscopic RPS with the cowboy technique for the removal of gastric submucosal tumors.

MATERIALS AND SURGICAL TECHNIQUE

A single-port access device was inserted at the naval (three 5-mm trocars), and a 5-mm trocar was inserted in the left lateral abdominal wall. A ligature was placed at the neck of the tumor, the loop was then tightened, and the knot was finally secured-a process referred to as the cowboy technique. This technique enables complete surgical excision and can be used for exophytic submucosal tumors of the stomach. Four patients underwent RPS with this technique, and the outcomes were good.

DISCUSSION

Our cowboy technique enables the safe full-thickness excision of gastric submucosal tumors with exophytic growth and is very useful in performing RPS.

Laparoscopic vs. open surgery for gastrointestinal stromal tumors of esophagogastric junction: A multicenter, retrospective cohort analysis with propensity score weighting

Objective

Laparoscopic resection is increasingly performed for gastrointestinal stromal tumors (GISTs). However, the laparoscopic approach for GISTs located in the esophagogastric junction (EGJ-GIST) is surgically challenging. This study compares the efficacy of laparoscopic surgery and the open procedure for EGJ-GIST through the propensity score weighting (PSW) method.

Methods

Between April 2006 and April 2018, 1,824 surgical patients were diagnosed with primary gastric GIST at four medical centers in South China. Of these patients, 228 were identified as EGJ-GISTs and retrospectively reviewed clinicopathological characteristics, operative information, and long-term outcomes. PSW was used to create the balanced cohorts.

Results

PSW was carried out in laparoscopic and open-surgery cohorts according to year of surgery, sex, age, body mass index (BMI), tumor size, mitotic rates and recurrence risk. After PSW, 438 patients consisting of 213 laparoscopic (L group) and 225 open surgery (O group) patients were enrolled. After PSW, the following measures in the L group were superior to those in the O group: median operative time [interquartile range (IQR)]: 100.0 (64.5−141.5)vs. 149.0 (104.0−197.5) min, P<0.001; median blood loss (IQR): 30.0 (10.0−50.0)vs. 50.0 (20.0−100.0) mL, P=0.002; median time to liquid intake (IQR): 3.0 (2.0−4.0)vs. 4.0 (3.0−5.0) d, P<0.001; median hospital stay (IQR): 6.0 (4.0−8.0)vs. 7.0 (5.0−12.0) d, P<0.001; and postoperative complications (10.3%vs. 22.7%, P=0.001). The median follow-up was 55 (range, 2−153) months in the entire cohort. No significant differences were detected in either relapse-free survival (RFS) [hazard ratio (HR): 0.372, 95% confidence interval (95% CI): 0.072−1.910, P=0.236) or overall survival (OS) (HR: 0.400, 95% CI: 0.119−1.343, P=0.138) between the two groups.

Conclusions

Laparoscopic surgery for EGJ-GIST is associated with the advantages of shorter operative time, reduced blood loss, shorter time to liquid intake, and shorter length of stay, all without compromising postoperative outcomes and long-term survival.

KIT and PDGFRa mutational patterns in Sardinian patients with gastrointestinal stromal tumors

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal malignancy of the gastrointestinal tract. We provide in the present article the molecular characterization of a series of primary GISTs in a cohort of Sardinian patients (Italy), with the aim to describe the patterns of KIT and PDGFRa mutations and the corresponding clinical features. Ninety-nine Sardinian patients with histologically-proven diagnosis of GIST were included in the study. Medical records and pathology reports were used to assess the demographic and clinical features of the patients and the disease at the time of the diagnosis. Formalin-fixed, paraffin-embedded tissue samples were retrieved for each case, and mutation analysis of the KIT and PDGFRa genes was performed. KIT and PDGFRa mutations were detected in 81.8% and 5% of the cases, respectively. The most common KIT mutation was W557_K558del in exon 11, while D842V in exon 18 was the most common PDGFRa genetic alteration; V561D was the only PDGFRa mutation found in exon 12. The global "wild-type" cases, with no mutations in either the KIT or PDGFRa genes, were 13 (13.1%). The mean survival of those patients was approximately 46.9 (±43.9) months. Globally, 86.9% of Sardinian patients with GIST had a KIT or PDGFRa mutation; the former were more frequent in comparison with other Italian cohorts, while PDGFRa mutations were rare. No statistical differences in survival between mutated and wild-type cases, and between KIT and PDGFRa mutated cases were detected in our study.

Gastrointestinal stromal tumors (GISTs) and synchronous intra-abdominal malignancies: case series of a single institution's experience

Background: Gastrointestinal stromal tumors (GISTs) quite often co-exist with other primary tumors, as seen in up to 33% of cases. In the literature such occurrences have primarily been described through case reports and rarely through case series, which is not sufficient to prove if there is an association between these two entities.

Materials and Methods: We conducted a retrospective study using medical and pathological records from sixty-nine patients who underwent surgical treatment for GIST in a single university surgical department between 2011 and 2019. Seven cases of GIST accompanying a synchronous primary tumor were identified and included in the study.

Results: Survival analysis comparing the overall survival of patients with single GIST versus patients with concurrent GIST and another primary tumor, has shown no statistically significant difference between these two groups (p = 0.19). However, when comparing the recurrence rate, patients with synchronous GISTs and another primary tumor have a statistically significant increased possibility for recurrence (p = 0.02). Statistical analysis comparing the size of GISTs between the two groups has shown that patients with single GIST have larger tumors than patients with synchronous tumors (p = 0.048).

Conclusions: The synchronous occurrence of GISTs and other intra-abdominal tumors is more common than previously considered, though it is not yet clear if there is a causal association for the concomitant occurrence. Further studies are required to elucidate the genetic and molecular mechanisms of carcinogenesis and progression associating GIST and synchronous tumors.

Deciding on the duration of adjuvant therapy in gastrointestinal stromal tumor

Introduction: The benefit of the tyrosine kinase inhibitor (TKI) imatinib mesylate in metastatic Gastrointestinal Stromal Tumors (GIST) leads to improved progression-free survival (PFS) and overall survival (OS). Clinical trials of adjuvant imatinib have provided data on the utility in management of primary GIST. There still remains uncertainty regarding the optimal duration of therapy.Areas covered: Here, we review the literature on the pivotal clinical trials evaluating adjuvant imatinib: ACOSOG Z9000/Z9001, EORTC 62024, Scandinavian Sarcoma Group XVIII, and PERSIST-5. The data from these studies that were analyzed included the patient population, length of therapy, and outcomes.Expert opinion: Clinical trial data demonstrate that adjuvant imatinib delays recurrence and appears to improve survival when taken for 3 years in high-risk patients; treatment for 5 years has been found to be safe, although difficult for patients to maintain adherence. These studies all incorporated slightly different patient populations based upon eligibility criteria for risk of recurrence, but support the use in patients with intermediate to high risk of disease recurrence. Data from these studies does not support treating those with low risk of recurrence or imatinib-insensitive mutations.

Incidence of gastrointestinal stromal tumor in Chinese urban population: A national population-based study

Background

Information on incidence of gastrointestinal stromal tumor (GIST), the most common type of mesenchymal tumor in gastrointestinal tract, was limited in China. This study aimed to estimate the incidence of GIST in urban population from mainland China in 2016.

Methods

Urban Employee Basic Medical Insurance (UEBMI) and Urban Residence Basic Medical Insurance (URBMI) in China were used. The denominator of incidence was the total person‐years of insured individuals in 2016 in the database, covering approximately 0.43 billion individuals. The numerator was the number of incident GIST cases in 2016.

Results

The crude incidence in 2016 was 0.40 per 100,000 person‐years (95% CI, 0.06–1.03). Male incidence was higher than female incidence (0.44 vs. 0.36, rate ratio: 1.22, p < 0.001). The mean age at diagnosis was 55.20 years (SD = 14.26) and the incidence among those aged 50 years or older was 2.63 times (0.84 vs. 0.32, p < 0.001) higher than those aged under 50. The highest incidence was observed in East China (2.29, 95% CI: 0.46–5.54).

Conclusions

The incidence of GIST in mainland China was lower than Europe, North America and Korea. The mean age at diagnosis of GIST in China was younger than that of Europe and Canada. This study provides useful information to further research, policy formulating and management of GIST.

A smooth muscle-derived, Braf-driven mouse model of gastrointestinal stromal tumor (GIST): evidence for an alternative GIST cell-of-origin

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumor of the gut. GISTs are thought to arise solely from interstitial cells of Cajal (ICC), a KIT-positive population that controls gut motility. Activating gain-of-function mutations in KIT and PDGFRA are the most frequent driver events, and most of these tumors are responsive to the tyrosine kinase inhibitor imatinib. Less common drivers include mutant BRAFV600E and these tumors are resistant to imatinib. A mouse model of GIST was recently reported using Etv1, the master transcriptional regulator of ICC-intramuscular (IM) and ICC-myenteric (MY), to induce mutant Braf expression. ICC hyperplasia was observed in Etv1CreERT2 ;BrafLSL-V600E/+ mice but loss of Trp53 was required for development of GIST. We identified previously expression of the pan-ErbB negative regulator, LRIG1, in two distinct subclasses of ICC [ICC-deep muscular plexus (DMP) in small intestine and ICC-submucosal plexus (SMP) in colon] and that LRIG1 regulated their development from smooth muscle cell progenitors. Using Lrig1CreERT2 to induce BrafV600E , we observed ICC hyperplasia beyond the confines of ICC-DMP and ICC-SMP expression, suggesting smooth muscle cells as the cell-of-origin. To examine this possibility, we selectively activated BrafV600E in smooth muscle cells. Myh11CreERT2 ;BrafLSL-V600E/+ mice developed not only ICC hyperplasia but also GIST and in the absence of Trp53 disruption. In addition to providing a simpler model for mutant Braf GIST, these results provide conclusive evidence for smooth muscle cells as an alternative cell-of-origin for GIST. © 2020 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Nomogram to Predict Preoperative Occult Peritoneal Metastasis of Gastrointestinal Stromal Tumors (GIST) Based on Imaging and Inflammatory Indexes

Background

Preoperative imaging examination is the primary method for diagnosing metastatic gastrointestinal stromal tumor (GIST), but it is associated with a high rate of missed diagnosis. Therefore, it is important to establish an accurate model for predicting occult peritoneal metastasis (PM) of GIST.

Patients and Methods

GIST patients seen between April 2002 and December 2018 were selected from an institutional database. Using multivariate logistic regression analyses, we created a nomogram to predict occult PM of GIST and validated it with an independent cohort from the same center. The concordance index (C-index), decision curve analysis (DCA) and a clinical impact curve (CIC) were used to evaluate its predictive ability.

Results

A total of 522 eligible GIST patients were enrolled in this study and divided into training (n=350) and validation cohorts (n=172). Factors associated with occult PM were included in the model: tumor size (odds ratio [OR] 1.194 95% confidence interval [CI], 1.034-1.378; p=0.016), primary location (OR 7.365 95% CI, 2.192-24.746; p=0.001), tumor capsule (OR 4.282 95% CI, 1.209-15.166; p=0.024), Alb (OR 0.813 95% CI, 0.693-0.954; p=0.011) and FIB (OR 2.322 95% CI, 1.410-3.823; p=0.001). The C-index was 0.951 (95% CI, 0.917-0.985) in the training cohort and 0.946 (95% CI, 0.900-0.992) in the validation cohort. In the training cohort, the prediction model had a sensitivity of 82.8%, a specificity of 93.8%, a positive predictive value of 54.7%, and a negative predictive value of 98.4%; the validation cohort values were 94.7%, 85.0%, 43.9% and 99.2%, respectively. DCA and CIC results showed that the nomogram had clinical value in predicting occult PM in GIST patients.

Conclusion

Imaging and inflammatory indexes are significantly associated with microscopic metastases of GIST. A nomogram including these factors would have an excellent ability to predict occult PM.

Factors Influencing the Steady-State Plasma Concentration of Imatinib Mesylate in Patients With Gastrointestinal Stromal Tumors and Chronic Myeloid Leukemia

Imatinib mesylate (IM) is the standard treatment for advanced, metastatic gastrointestinal stromal tumors (GISTs) and chronic myeloid leukemia (CML) with a fixed daily standard dosage via the oral route. Interindividual and intraindividual variability in plasma concentrations have been closely linked to the efficacy of IM therapy. Therefore, this review identifies and describes the key factors influencing the plasma concentration of IM in patients with GISTs and CML. We used the following keywords to search the PubMed, EMBASE, Ovid, Wangfang, and CNKI databases to identify published reports: IM, plasma concentration, GISTs, CML, drug combination/interaction, pathology, and genotype/genetic polymorphism, either alone or in combination. This literature review revealed that only 10 countries have reported the mean concentrations of IM in GISTs or CML patients and the clinical outcomes in different ethnic groups and populations. There were totally 24 different gene polymorphisms, which were examined for any potential influence on the steady-state plasma concentration of IM. As a result, some genotype locus made discrepant conclusion. Herein, the more sample capacity, multicenter, long-term study was worthy to carry out. Eleven reports were enumerated on clinical drug interactions with IM, while there is not sufficient information on the pharmacokinetic parameters altered by drug combinations with IM that could help in investigating the actual drug interactions. The drug interaction with IM should be paid more attention in the future research.

Robotic Wedge Resection for Unfavorably Located Gastric Gastrointestinal Stromal Tumors: Perioperative and Long-Term Oncological Outcomes

Background and Objectives: Robotic wedge resection for gastrointestinal stromal tumors (GISTs) located in the stomach offers remarkable advantages, especially for lesions in unfavorable places. Although promising, long-term oncological results associated with this surgical procedure are poorly represented in literature. We present our experience of robotic wedge resection with gastrotomy for challenging gastric GISTs, in terms of both surgical outcomes and long-term oncological results. Methods: From April 2014 to February 2020, all consecutive patients affected by unfavorably located gastric GISTs (based on the Privette/Al-Thani classification system) underwent robotic wedge resection. Clinicopathological, surgical, and long-term oncological results were retrospectively analyzed. Results: Seventeen patients underwent full-thickness gastric wedge resection with primary robot-sewn closure of the defect. In 64.7% of cases, the lesion was ≥5 cm in diameter. No conversion nor tumor rupture were recorded and complete R0 resection was achieved in all cases. Median hospital stay was 5 days (range 3-18). At a median follow-up of 46 months (range 7-67), the disease-free survival rate and the overall survival rate were 94.1% and 82.3%, respectively. Conclusions: Robotic wedge resection with gastrotomy and robotic-sewn suture is a safe and feasible procedure for GISTs located in unfavorable anatomic positions, without compromising oncological outcomes.

Abnormal MGMT Promoter Methylation in Gastrointestinal Stromal Tumors: Genetic Susceptibility and Association with Clinical Outcome

Purpose

KIT/PDGFRA wild-type (WT) gastrointestinal stromal tumors (GISTs) represent a heterogeneous subgroup of GISTs that lack KIT or PDGFRA mutations and possess distinct genetic alterations and primary resistance to imatinib. Succinate dehydrogenase (SDH)-deficient GISTs comprise the largest subpopulation of WT GISTs that are characterized by loss-of-function of SDH. O6-methylguanine-DNA methyltransferase (MGMT) is a specific DNA repair enzyme that has been identified as a predictor of positive treatment response to alkylating agents in a variety of cancers. The aim of this study was to evaluate the expression of MGMT and the prevalence of MGMT promoter methylation in GISTs and to determine the association between MGMT promoter methylation and clinicopathological characteristics and clinical outcomes.

Patients and Methods

A heterogeneous cohort of 137 primary GISTs that confirmed by immunohistochemistry and KIT/PDGFRA mutation analysis were retrospectively selected and analyzed for MGMT expression and MGMT promoter methylation using immunohistochemical staining and methylation-specific PCR (MSP). A concordance analysis between MGMT promoter methylation and clinicopathological characteristics and prognosis was also performed.

Results

A total of 44.5% (65/137) of GIST patients displayed loss of MGMT protein expression, and 10.9% (15/137) of these patients exhibited MGMT promoter methylation. However, no significant correlation was observed between the loss of MGMT protein expression and MGMT promoter methylation. WT GISTs possessing an epithelioid or mixed phenotype, particularly those that were SDH-deficient, displayed a markedly higher prevalence of MGMT promoter methylation compared to that in KIT/PDGFRA mutated GISTs. Moreover, MGMT promoter methylation was identified as a potential independent prognostic factor for OS and DFS in patients with GIST.

Conclusion

MGMT promoter methylation is particularly frequent in SDH-deficient GISTs and in WT GISTs possessing an epithelioid/mixed phenotype, and knowledge of this methylation status may offer a novel potential therapeutic option for WT GISTs.

MRI Texture-Based Models for Predicting Mitotic Index and Risk Classification of Gastrointestinal Stromal Tumors

BACKGROUND

Treatment regimens and prognoses of gastrointestinal stromal tumors (GIST) are quite different for tumors in different risk categories. Accurate preoperative grading of tumors is important for avoiding under- or overtreatment.

PURPOSE

To develop and validate an MRI texture-based model to predict the mitotic index and its risk classification.

STUDY TYPE

Retrospective.

POPULATION

Ninety-one patients with histologically-confirmed GIST; 64 patients in a training cohort, and 27 patients in a test cohort.

FIELD STRENGTH/SEQUENCE

T₂ -weighted imaging (T₂ WI), diffusion-weighted imaging (DWI), and dynamic contrast-enhanced three-dimensional volumetric interpolated breath-hold examination (3D-VIBE) at 1.5T.

ASSESSMENT

GIST images were manually segmented by two independent radiologists using ITK-SNAP software and MRI features were extracted using Pyradiomics. Two pathologists reviewed the tissue specimens of the tumors to identify the mitotic index and risk classification in consensus.

STATISTICAL TESTS

The least absolute shrinkage and selection operator (LASSO) regression method was used to select texture features. A logistic regression model was established based on the radiomic score (radscore), tumor location, and maximum diameter to predict tumor classification and develop a nomogram. Receiver operator characteristic (ROC) curves were used to evaluate the ability of the nomogram to distinguish between two tumors with different risk classifications, and a calibration curve was used to evaluate the consistency between the predicted risk and the actual risk.

RESULTS

The texture signature achieved high efficacy in predicting the mitotic index area under the curve ([AUC], 0.906; 95% confidence interval [CI]: 0.813, 0.961). A nomogram for prediction of the risk classification of GIST, which incorporated this texture signature together with maximum tumor diameter and location, allowed good discrimination in the training cohort (AUC, 0.878; 95% CI: 0.769, 0.960) and the validation cohort (AUC, 0.903; 95% CI: 0.732, 0.922).

DATA CONCLUSION

The texture-based model can be used to predict GIST mitotic index and risk classification preoperatively.

LEVEL OF EVIDENCE

2.

TECHNICAL EFFICACY STAGE

3.

Meta-Analysis on the Efficacy and Safety of Laparoscopic Surgery for Large Gastric Gastrointestinal Stromal Tumors

BACKGROUND

The aim of this study was to conduct a meta-analysis comparing the safety and feasibility of laparoscopic versus open resection for gastric gastrointestinal stromal tumors (GISTs) larger than 5 cm.

METHOD

We searched the Cochrane Library, PubMed, and Embase for relevant articles. Randomized and nonrandomized clinical trials were identified and included in this study. Searching for related articles on large GIST (>5 cm) for laparoscopic resection (laparoscopic group [LAPG]) and open resection (open group [OG]), RevMan 5.3 was used for data analysis, comparing 2 groups of operation time, intraoperative blood loss, complications, length of hospital stay, recurrence rate, disease-free survival, and overall survival.

RESULTS

Seven studies including 440 patients were identified for the meta-analysis. Meta-analysis revealed that LAPG had less bleeding, shorter postoperative hospital stay, and a better 5-year disease-free survival. There was no significant difference between LAPG and OG in operation time, postoperative complications, recurrence rate, and overall survival.

CONCLUSION

Laparoscopic resection of large (>5 cm) GIST is safe and feasible and has the advantages of less intraoperative blood loss and fast postoperative recovery, with a good outcome in the recent oncology.

Strategies for care of patients with gastrointestinal stromal tumor or soft tissue sarcoma during COVID-19 pandemic: A guide for surgical oncologists

The coronavirus disease-2019 (COVID-19) pandemic is deeply impacting the accessibility of cancer patients to surgery. In resource-limited conditions, the standard of care might not be deliverable, but evidence to support alternative management strategies often exists. By revisiting available treatment options, this review provides surgical oncologists with an evidence-based framework for treating patients with gastrointestinal stromal tumor, extremity/truncal soft tissue sarcoma, and retroperitoneal sarcoma to rapidly adapt their decision-making to the constant evolution of the COVID-19 pandemic.