Gastrointestinal Stromal Tumors

Multiple jejunal gastrointestinal stromal tumors and Neurofibromatosis type 1: A rare association

INTRODUCTION AND IMPORTANCE

The association between gastrointestinal stromal tumor (GIST), mesenchymal tumor arising from the interstitial cells of cajal and Neurofibromatosis type 1 (NF1), an autosomal dominant disease has been reported in the literature. GIST in NF1 patients are multiple and located in the small intestine. Tumorigenesis in NF1 associated GIST is different to that of sporadic GIST and hence the treatment. Here we report a rare case of an NF1 patient with multiple jejunal GISTs.

CASE PRESENTATION

We here present a rare case of a 57-year-old male diagnosed with NF1 30 years back, presented in our emergency department with complaints of black, tarry stools later diagnosed to have multiple GIST in jejunum. Contrast enhanced computed tomography (CECT) of the abdomen showed a large 10.1 × 7.33 × 6.2 cm heterogeneous, exophytic, solid mass with cystic areas originating from the jejunum. The microscopic examination of the specimen showed spindle shaped tumor cells while immunohistochemistry showed CD117 (c-KIT) and DOG-1 positivity. The primary treatment was complete surgical excision of the tumor.

CLINICAL DISCUSSION

The incidence of GISTs in NF1 patient is around 6-7%; however, concomitant presence of multiple GISTs is rare. CECT of abdomen along with histopathological and immunohistochemistry studies are diagnostic. The management of GIST includes surgical and adjuvant therapy methods based on the tumorigenesis and recurrent risk stratification.

CONCLUSION

Early clinical suspicion and imaging aids in early detection of the tumor in patients with NF1 presenting with gastrointestinal symptoms. Postoperatively, screening for recurrence with radiology is of utmost importance.

Targeted therapy in SDH-deficient GIST

The medical management of advanced gastrointestinal stromal tumors (GIST) has improved with the development of tyrosine kinase inhibitors (TKIs) targeting KIT and PDGFRA mutations. However, approximately 5-10% of GIST lack KIT and PDGFRA mutations, and about a half are deficient in succinate dehydrogenase (SDH) that promotes carcinogenesis by the cytoplasmic accumulation of succinate. This rare group of GIST primarily occurs in the younger patients than other subtypes, and is frequently associated with hereditary syndromes. The role of TKIs in patients with SDH-deficient GIST is controversial, with conflicting results; thus, there is an urgent need to uncover the disease mechanisms, treatment patterns, and responses to systemic therapy among these patients. Here, based on an extensive literature search, we have provided a rigorous overview of the current evidence on the medical treatment of SDH-deficient GIST.

Recent Progress and Challenges in the Diagnosis and Treatment of Gastrointestinal Stromal Tumors

Simple Summary

Gastrointestinal stromal tumors (GIST) are potentially malignant tumors and require evidence-based surgical and/or medical treatment. Laparoscopy has similar safety and prognostic outcomes to those of laparotomy and is currently a standard procedure for localized GISTs. However, surgery for gastric GISTs less than 2 cm may be re-evaluated due to the indolent nature of the GIST and other competing risks among GIST patients. A work-up with endoscopy and endoscopic ultrasonography as well as endoscopic or percutaneous biopsy is important for the preoperative diagnosis of GISTs. Medical treatment with tyrosine kinase inhibitors is the mainstay for recurrent/metastatic GISTs. The activity of an individual drug is well correlated with gene alterations, and, in the era of precision medicine, cancer genome profiling should be considered before medical treatment.

Abstract

Gastrointestinal stromal tumors (GISTs) are the most frequent malignant mesenchymal tumors in the gastrointestinal tract. The clinical incidence of GISTs is estimated 10/million/year; however, the true incidence is complicated by frequent findings of tiny GISTs, of which the natural history is unknown. The initial work-up with endoscopy and endoscopic ultrasonography plays important roles in the differential diagnosis of GISTs. Surgery is the only modality for the permanent cure of localized GISTs. In terms of safety and prognostic outcomes, laparoscopy is similar to laparotomy for GIST treatment, including tumors larger than 5 cm. GIST progression is driven by mutations in KIT or PDGFRA or by other rare gene alterations, all of which are mutually exclusive. Tyrosine kinase inhibitors (TKIs) are the standard therapy for metastatic/recurrent GISTs. Molecular alterations are the most reliable biomarkers for TKIs and for other drugs, such as NTRK inhibitors. The pathological and genetic diagnosis prior to treatment has been challenging; however, a newly developed endoscopic device may be useful for diagnosis. In the era of precision medicine, cancer genome profiling by targeted gene panel analysis may enable potential targeted therapy even for GISTs without KIT or PDGFRA mutations.

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.

Imatinib inhibits the malignancy of hepatocellular carcinoma by suppressing autophagy

Hepatocellular carcinoma (HCC) is one of the most common cancers and is associated with high morbidity and mortality rates. Recent research indicated that imatinib, a selective tyrosine kinase inhibitor, suppressed the growth of hepatocellular carcinoma. However, the effect of imatinib on HCC and its mechanism remain under investigated. In this study, we demonstrated that imatinib inhibited the proliferation, migration and invasion of HCC cells in vitro and exerted antitumour effects on HCC xenografts in mice in vivo. Imatinib treatment decreased the phosphorylation of AKT and increased the levels of both p62 (protein sequestosome 1) and LC3 (microtubule-associated protein 1A/1B-light chain 3) in HCC cells and HCC xenografts. Scanning confocal microscopy analysis with a mRFP-GFP-LC3 reporter and transmission electron microscopy analysis revealed that imatinib suppressed the autophagic flux by obstructing the formation of autolysosomes. Moreover, imatinib reversed the autophagy induced by sorafenib, and combined treatment with imatinib and sorafenib exerted a synergetic effect in HCC cells compared with monotherapy. Our collective data suggested that imatinib may target HCC by acting as an inhibitor of both tyrosine kinase and autophagy; here, we propose that imatinib could be a promising therapeutic agent for HCC in the clinic.

Quantitative proteomic analysis of aberrant expressed lysine acetylation in gastrointestinal stromal tumors

BACKGROUND

Gastrointestinal stromal tumor (GIST) is a common digestive tract tumor with high rate of metastasis and recurrence. Currently, we understand the genome, transcriptome and proteome in GIST. However, posttranscriptional modification features in GIST remain unclear. In the present study, we aimed to construct a complete profile of acetylome in GIST.

METHODS

Five common protein modifications, including acetylation, succinylation, crotonylation, 2-hydroxyisobutyrylation, and malonylation were tested among GIST subgroups and significantly differentially- expressed lysine acetylation was found. The acetylated peptides labeled with Tandem Mass Tag (TMT)under high sensitive mass spectrometry, and some proteins with acetylation sites were identified. Subsequently, these proteins and peptides were classified into high/moderate (H/M) risk and low (L) risk groups according to the modified NIH classification standard. Furthermore, cell components, molecular function, biological processes, KEGG pathways and protein interaction networks were analyzed.

RESULTS

A total of 2904 acetylation sites from 1319 proteins were identified, of which quantitative information of 2548 sites from 1169 proteins was obtained. Finally, the differentially-expressed lysine acetylation sites were assessed and we found that 42 acetylated sites of 38 proteins were upregulated in the H/M risk group compared with the L risk group, while 48 acetylated sites of 44 proteins were downregulated, of which Ki67 K1063Ac and FCHSD2 K24Ac were the two acetylated proteins that were most changed.

CONCLUSIONS

Our novel findings provide further understanding of acetylome in GIST and might demonstrate the possibility in the acetylation targeted diagnosis and therapy of GIST.

The EMA assessment of avapritinib in the treatment of gastrointestinal stromal tumours harbouring the PDGFRA D842V mutation

Avapritinib is a protein kinase inhibitor designed to selectively inhibit oncogenic KIT and platelet-derived growth factor receptor alpha (PDGFRA) mutants by targeting the active conformation of the kinase. On 24 September 2020, a marketing authorisation valid through the European Union was issued for avapritinib as treatment of adult patients with unresectable or metastatic gastrointestinal stromal tumours (GIST) harbouring the PDGFRA D842V mutation. The drug was evaluated in an open-label, phase I, first-in-human, dose-escalation, open-label study to evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics, and efficacy of avapritinib in adults with unresectable or metastatic GIST. The benefit of avapritinib was observed in patients with GIST harbouring the PDGFRA D842V mutation. The overall response rate was 95% (95% confidence interval 82.3%-99.4%), with a median duration of response of 22.1 months (95% confidence interval 14.1-not estimable months). The most common adverse events were nausea, fatigue, anaemia, periorbital and face oedema, hyperbilirubinaemia, diarrhoea, vomiting, increased lacrimation, and decreased appetite. Most of the reported cognitive effects were mild memory impairment. Rarer events were cases of severe encephalopathy and intracranial or gastrointestinal bleeding. The aim of this manuscript is to summarise the scientific review of the application leading to regulatory approval in the European Union.

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Avapritinib is a protein kinase inhibitor designed to inhibit oncogenic KIT and PDGFRA mutants.

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A marketing authorisation was issued for avapritinib as treatment of patients with GIST harbouring the PDGFRA D842V mutation.

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The overall response rate was 95% (95% CI 82.3-99.4), with a median duration of response of 22.1 months (95% CI 14.1-NE).

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The most common adverse events were nausea, fatigue, anaemia, periorbital and face oedema, hyperbilirubinaemia and diarrhoea.

Current knowledge of primary prostatic extra-gastrointestinal stromal tumor: a case report and review of the literature

The patient was a 62-year-old man diagnosed as having prostatic extra-gastrointestinal stromal tumor (EGIST) who was treated with imatinib. No recurrence or metastasis was found after a 6-month follow-up. We identified 14 cases of prostatic primary EGIST in PubMed and summarized these cases with our case. The patients' ages ranged from 31 to 78 years (average: 53.6 years), and most patients' prostate-specific antigen (PSA) concentrations were within normal limits (92.9%, 13/14). All patients underwent imaging examinations; prostatic masses measured 6 to 14.2 cm (mean: 9.43 cm), and imaging excluded secondary prostatic masses from the intestinal tract. By immunohistochemical staining, the tumors were positive for cluster of differentiation (CD)117 (71.4%, 10/14), DOG1 (100%, 7/7), and CD34 (100%, 14/14), and negative for smooth muscle actin (SMA) (71.4%, 10/14), desmin (100%, 11/11), and S100 (100%, 12/12). Treatment depended on the results of the gene mutation detection as well as the risk estimation according to tumor size and microscopic mitotic rates (>5 per 50 high-power fields: 60%, 6/10). Among the 12 patients with reported outcomes, nine achieved good results (no recurrence or metastasis), one achieved reduced mass volume, one experienced recurrence, and one died.

Extracellular Vesicles: A Novel Tool Facilitating Personalized Medicine and Pharmacogenomics in Oncology

Biomarkers that can guide cancer therapy based on patients' individual cancer molecular signature can enable a more effective treatment with fewer adverse events. Data on actionable somatic mutations and germline genetic variants, studied by personalized medicine and pharmacogenomics, can be obtained from tumor tissue or blood samples. As tissue biopsy cannot reflect the heterogeneity of the tumor or its temporal changes, liquid biopsy is a promising alternative approach. In recent years, extracellular vesicles (EVs) have emerged as a potential source of biomarkers in liquid biopsy. EVs are a heterogeneous population of membrane bound particles, which are released from all cells and accumulate into body fluids. They contain various proteins, lipids, nucleic acids (miRNA, mRNA, and DNA) and metabolites. In cancer, EV biomolecular composition and concentration are changed. Tumor EVs can promote the remodeling of the tumor microenvironment and pre-metastatic niche formation, and contribute to transfer of oncogenic potential or drug resistance during chemotherapy. This makes them a promising source of minimally invasive biomarkers. A limited number of clinical studies investigated EVs to monitor cancer progression, tumor evolution or drug resistance and several putative EV-bound protein and RNA biomarkers were identified. This review is focused on EVs as novel biomarker source for personalized medicine and pharmacogenomics in oncology. As several pharmacogenes and genes associated with targeted therapy, chemotherapy or hormonal therapy were already detected in EVs, they might be used for fine-tuning personalized cancer treatment.

Fertility considerations in targeted biologic therapy with tyrosine kinase inhibitors: a review

PURPOSE

To review the impact of tyrosine kinase inhibitors (TKIs) on fertility in men and women, embryo development, and early pregnancy, and discuss considerations for fertility preservation in patients taking TKIs.

METHODS

A comprehensive literature search using the PubMed database was performed through February 2021 to evaluate the current literature on imatinib, nilotinib, dasatinib, and bosutinib as it relates to fertility and reproduction. Published case series were analyzed for pregnancy outcomes.

RESULTS

TKIs adversely affect oocyte and sperm maturation, gonadal function, and overall fertility potential in a self-limited manner. There are insufficient studies regarding long-term consequences on fertility after discontinuation of TKIs. A total of 396 women and 236 men were on a first- or second-generation TKI at the time of conception. Of the women with detailed pregnancy and delivery outcomes (n = 361), 51% (186/361) resulted in a term birth of a normal infant, 4.3% (16/361) of pregnancies had a pregnancy complication, and 5% (20/361) of pregnancies resulted in the live birth of an infant with a congenital anomaly. About 22% of pregnant women (87/396) elected to undergo a termination of pregnancy, while 16% (63/396) of pregnancies ended in a spontaneous abortion. In contrast, of the 236 men, 87% conceived pregnancies which resulted in term deliveries of normal infants. Elective terminations, miscarriage rate, pregnancy complication rate, and incidence of a congenital malformation were all less than those seen in females (4%, 3%, 2%, and 2.5%, respectively).

CONCLUSION

Women should be advised to avoid conception while taking a TKI. Women on TKIs who are considering pregnancy should be encouraged to plan the pregnancy to minimize inadvertent first trimester exposure. In women who conceive while taking TKIs, the serious risk of relapse due to discontinuation of TKI should be balanced against the potential risks to the fetus. The risk of teratogenicity to a fathered pregnancy with TKI use is considerably lower. Fertility preservation for a woman taking a TKI can be considered to plan a pregnancy with a minimal TKI-free period. With careful monitoring, providers may consider a TKI washout period followed by controlled ovarian stimulation to cryopreserve oocytes or embryos, with a plan to resume TKIs until ready to conceive or to transfer an embryo to achieve pregnancy quickly. Fertility preservation is also indicated if a patient on TKI is requiring a gonadotoxic therapy or reproductive surgery impacting fertility.

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.

Gastrointestinal stromal tumours

Gastrointestinal stromal tumours (GIST) have an incidence of ~1.2 per 10⁵ individuals per year in most countries. Around 80% of GIST have varying molecular changes, predominantly mutually exclusive activating KIT or PDGFRA mutations, but other, rare subtypes also exist. Localized GIST are curable, and surgery is their standard treatment. Risk factors for relapse are tumour size, mitotic index, non-gastric site and tumour rupture. Patients with GIST with KIT or PDGFRA mutations sensitive to the tyrosine kinase inhibitor (TKI) imatinib that are at high risk of relapse have improved survival with adjuvant imatinib treatment. In advanced disease, median overall survival has improved from 18 months to >70 months since the introduction of TKIs. The role of surgery in the advanced setting remains unclear. Resistance to TKIs arise mainly from subclonal selection of cells with resistance mutations in KIT or PDGFRA when they are the primary drivers. Advanced resistant GIST respond to second-line sunitinib and third-line regorafenib, as well as to the new broad-spectrum TKI ripretinib. Rare molecular forms of GIST with alterations involving NF1, SDH genes, BRAF or NTRK genes generally show primary resistance to standard TKIs, but some respond to specific inhibitors of the activated genes. Despite major advances, many questions in both advanced and localized disease remain unanswered.

Establishment and characterization of NCC-SS4-C1: a novel patient-derived cell line of synovial sarcoma

Synovial sarcoma (SS) is defined as a monomorphic blue spindle cell sarcoma showing variable epithelial differentiation, and is characterized by a specific fusion gene, SS18-SSX. Although SS is rare, it accounts for approximately 8% of all soft tissue sarcomas, which occupies a significant proportion of soft tissue tumors. The prognosis of SS is unfavorable, with 5-year survival rate of 50-60%, and only a few anti-cancer agents are recommended for its treatment. Thus, we need to urgently establish novel treatment methods. Patient-derived cell lines are essential tools in basic research and pre-clinical studies. However, there are only 4 publicly available SS cell lines. Therefore, we established a novel SS cell line, NCC-SS4-C1, using surgically resected tumor tissues of a patient with SS. The cell line maintained the characteristic fusion gene, SS18-SSX1, and copy number alteration, in concordance with the original tumor. The cells also exhibited moderate cell proliferation, invasion ability, and spheroid formation ability. Moreover, a drug-screening test using 4 SS cell lines, including NCC-SS4-C1, demonstrated the significant anti-proliferative effects of ALK and HDAC inhibitors. Thus, we concluded that the NCC-SS4-C1 cell line is a useful tool for basic and pre-clinical studies of SS.

Identification and Therapeutic Targeting of GPR20, Selectively Expressed in Gastrointestinal Stromal Tumors, with DS-6157a, a First-in-Class Antibody-Drug Conjugate

Currently, the only approved treatments for gastrointestinal stromal tumor (GIST) are tyrosine kinase inhibitors (TKI), which eventually lead to the development of secondary resistance mutations in KIT or PDGFRA and disease progression. Herein, we identified G protein-coupled receptor 20 (GPR20) as a novel non-tyrosine kinase target in GIST, developed new GPR20 IHC, and assessed GPR20 expression in cell lines, patient-derived xenografts, and clinical samples from two institutes (United States and Japan). We studied GPR20 expression stratified by treatment line, KIT expression, GIST molecular subtype, and primary tumor location. We produced DS-6157a, an anti-GPR20 antibody-drug conjugate with a novel tetrapeptide-based linker and DNA topoisomerase I inhibitor exatecan derivative (DXd). DS-6157a exhibited GPR20 expression-dependent antitumor activity in GIST xenograft models including a GIST model resistant to imatinib, sunitinib, and regorafenib. Preclinical pharmacokinetics and safety profile of DS-6157a support its clinical development as a potential novel GIST therapy in patients who are refractory or have resistance or intolerance to approved TKIs. SIGNIFICANCE: GPR20 is selectively expressed in GIST across all treatment lines, regardless of KIT/PDGFRA genotypes. We generated DS-6157a, a DXd-based antibody-drug conjugate that exhibited antitumor activity in GIST models by a different mode of action than currently approved TKIs, showing favorable pharmacokinetics and safety profiles.This article is highlighted in the In This Issue feature, p. 1307.

Long-term Outcomes of Endoscopic Resection for Gastric Subepithelial Tumors

OBJECTIVE

The purpose of the current study was to analyze the safety and efficacy of endoscopic resection for gastric subepithelial tumors (SETs) using long-term patient outcome data.

PATIENTS AND METHODS

A retrospective analysis of 73 consecutive patients with gastric SETs was performed from June 2014 to December 2016. The treatment methods included submucosal dissection, submucosal excavation or endoscopic full-thickness resection (EFTR). In addition to epidemiological data (sex and age), tumor size, surgical parameters, length of stay, complications, costs, and endoscopic, clinicopathologic, and follow-up data were analyzed to compare treatments.

RESULTS

The complete resection rate was 97.3% (71/73). Three patients experienced complications (4.1%), including 2 with delayed perforation and 1 with perioperative infection. The median postoperative feeding time was 3 days, and the median postoperative hospital stay was 5 days. The median follow-up period was 19 months, with no patient death or tumor recurrence. Among the 38 patients with gastrointestinal stromal tumors, the complete resection rate was 97.4% (37/38). The complete resection and complication rates between the endoscopic submucosal excavation (ESE) group and the EFTR group were not statistically significant. There was no recurrence or metastasis detected among either group; however, the ESE group had earlier postoperative feeding, a shorter postoperative hospital stay, and less hospitalization expenses.

CONCLUSIONS

Endoscopic resection for gastric SETs (<3 cm) is safe and feasible concerning medium-term and long-term effects. Compared with the EFTR group, the ESE group had earlier postoperative feeding, a shorter postoperative hospital stay, and less hospitalization expenses. Even so, gastric SETs with malignant potential are at risk of recurrence. Larger prospective multicenter studies are warranted.

GIST associated with von recklinghausen disease: Report of two cases and review of literature

INTRODUCTION AND IMPORTANCE

Neurofibromatosis type 1 (NF1), or Von Recklinghausen's disease, is an autosomal dominant condition that affects the central nervous system. Gastrointestinal stromal tumor (GIST) refers to non-epithelial tumors of the gastrointestinal tract lacking smooth muscle structural features and schwann cell immunohistochemical characteristics. The risk of patients with NF1 to develop a GIST is 7%.

CASE PRESENTATION

GIST is a soft tissue sarcoma that probably arises from the interstitial Cajal cells of the intestine. GIST associated with NF1 syndrome appears to have a distinct phenotype, occurring in younger patients compared to sporadic GIST.

CLINICAL DISCUSSION

The clinical presentation can be highly variable, the association of gastrointestinal tumors associated with Von Recklinghausen's disease is up to 7%, postoperative treatment with imatinib is reserved for patients with a high risk of recurrence.

CONCLUSION

The treatment of primary GIST is complete surgical resection with free microscopic margins and an intact pseudocapsule.

Survival Outcomes Associated With 3 Years vs 1 Year of Adjuvant Imatinib for Patients With High-Risk Gastrointestinal Stromal Tumors: An Analysis of a Randomized Clinical Trial After 10-Year Follow-up

Importance

Adjuvant imatinib is associated with improved recurrence-free survival (RFS) when administered after surgery to patients with operable gastrointestinal stromal tumor (GIST), but its influence on overall survival (OS) has remained uncertain.

Objective

To evaluate the effect of adjuvant imatinib on OS of patients who have a high estimated risk for GIST recurrence after macroscopically complete surgery.

Design, Setting, and Participants

In this open-label, randomized (1:1), multicenter phase 3 clinical trial conducted in Finland, Germany, Norway, and Sweden, 400 patients who had undergone macroscopically complete surgery for GIST with a high estimated risk for recurrence according to the modified National Institutes of Health Consensus Criteria were enrolled between February 2004 and September 2008. Data for this follow-up analysis were analyzed from September to November, 2019.

Interventions

Imatinib 400 mg/d administered orally for either 12 months or 36 months after surgery.

Main Outcomes And Measures

The primary end point was RFS; the secondary objectives included OS and treatment safety.

Results

The intention-to-treat cohort consisted of 397 patients (12-month group, 199; 36-month group, 198; 201 men and 196 women; median [IQR] age, 62 (51-69) years and 60 (51-67) years, during a median follow-up time of 119 months after the date of randomization, 194 RFS events and 96 OS events were recorded in the intention-to-treat population. Five-year and 10-year RFS was 71.4% and 52.5%, respectively, in the 36-month group and 53.0% and 41.8% in the 12-month group (hazard ratio [HR], 0.66; 95% CI, 0.49-0.87; P = .003). In the 36-month group, 5-year OS and 10-year OS rates were 92.0% and 79.0%, respectively, and in the 12-month group 85.5% and 65.3% (HR, 0.55; 95% CI, 0.37-0.83; P = .004). The results were similar in the efficacy population, from which 15 patients who did not have GIST in central pathology review and 24 patients who had intra-abdominal metastases removed at surgery were excluded (36-month group, 10-year OS 81.6%; 12-month group, 66.8%; HR, 0.50; 95% CI, 0.32-0.80; P = .003). No new safety signals were detected.

Conclusions and Relevance

Three years of adjuvant imatinib is superior in efficacy compared with 1 year of imatinib. Approximately 50% of deaths may be avoided during the first 10 years of follow-up after surgery with longer adjuvant imatinib treatment.

Trial Registration

ClinicalTrials.gov Identifier: NCT00116935.

Efficacy evaluation of nilotinib treatment in different genomic subtypes of gastrointestinal stromal tumors: A meta-analysis and systematic review

Nilotinib has been used as a third-line drug for gastrointestinal stromal tumors (GISTs) after a failure of sunitinib. In this study, we aimed to evaluate the efficacy of nilotinib in different genomic subtypes of GISTs. We searched the English articles through EMBASE, Cochrane Library and PubMed Database regarding to the use of nilotinib on GISTs, which published up to February 15, 2019. Inclusion criteria were: GISTs patients received nilotinib in a clinical trial and had detailed genetic subtype records (such as KIT exon 9, KIT exon 11, or PDGFRA mutations, or wild-type). The clinical benefit rate was used to assess the efficacy of nilotinib. A total of 3 studies involving 218 GISTs were included in this meta-analysis. The overall OR (KIT group vs WT group) was 3.26 (95% CI: 1.14-9.28; P = 0.027, P_{heterogeneity} = 0.613). The overall OR in KIT exon 11 group vs WT group was 5.30 (95% CI: 1.79-15.68; P = 0.003, P_{heterogeneity} = 0.409). The overall OR in KIT exon 9 group vs WT group was 0.13 (95% CI: 0.02-0.86; P = 0.035, P_{heterogeneity} = 0.229). The overall OR in KIT exon 11 group vs exon 9 group was 9.96 (95% CI: 0.39-254.66; P < 0.0001, P_{heterogeneity} = 0.024). Different genotypes of GISTs showed different responses to nilotinib, and KIT exon 11-mutant GISTs mostly benefited from nilotinib, followed by KIT exon 9-mutant or WT one.

Canadian Consensus for Biomarker Testing and Treatment of TRK Fusion Cancer in Adults

The tyrosine receptor kinase (TRK) inhibitors larotrectinib and entrectinib were recently approved in Canada for the treatment of solid tumours harbouring neurotrophic tyrosine receptor kinase (NTRK) gene fusions. These NTRK gene fusions are oncogenic drivers found in most tumour types at a low frequency (<5%), and at a higher frequency (>80%) in a small number of rare tumours (e.g., secretory carcinoma of the salivary gland and of the breast). They are generally mutually exclusive of other common oncogenic drivers. Larotrectinib and entrectinib have demonstrated impressive overall response rates and tolerability in Phase I/II trials in patients with TRK fusion cancer with no other effective treatment options. Given the low frequency of TRK fusion cancer and the heterogeneous molecular testing landscape in Canada, identifying and optimally managing such patients represents a new challenge. We provide a Canadian consensus on when and how to test for NTRK gene fusions and when to consider treatment with a TRK inhibitor. We focus on five tumour types: thyroid carcinoma, colorectal carcinoma, non-small cell lung carcinoma, soft tissue sarcoma, and salivary gland carcinoma. Based on the probability of the tumour harbouring an NTRK gene fusion, we also suggest a tumour-agnostic consensus for NTRK gene fusion testing and treatment. We recommend considering a TRK inhibitor in all patients with TRK fusion cancer with no other effective treatment options.

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.

Small bowel gastrointestinal stromal tumor presenting with gastrointestinal bleeding in patient with type 1 Neurofibromatosis: Management and laparoscopic treatment. Case report and review of the literature

INTRODUCTION AND IMPORTANCE

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal neoplasm of the gastrointestinal tract. It may be asymptomatic; nevertheless, gastrointestinal bleeding is the most frequent symptom, due to mucosal erosion. Its poor lymph node metastatic spread makes GIST often suitable of minimally invasive surgical approach. The importance of this study is to increase the awareness among physicians about this condition in particular scenarios as in our case and to stress the role of laparoscopic surgery.

CASE PRESENTATION

A 74-year-old female patient presented to the emergency department with hematemesis, followed by haematochezia and melena. The patient had a medical history of type 1 Neurofibromatosis (NF1). She underwent, after CT scan, esophagogastroduodenoscopy, and endoscopic haemostasis. Finally, we performed a laparoscopic resection of a mass of the first jejunal loop. The postoperative period was predominantly uneventful. Pathological examination confirmed a low-risk GIST.

CLINICAL DISCUSSION

Proximal jejunal GIST may cause an upper and lower gastrointestinal bleeding. A multidisciplinary team approach is mandatory for the correct management of this disease and its complications (bleeding). GISTs are indicated as the most commonly gastrointestinal NF1 associated tumours. In case of localised and resectable GIST surgical treatment is the mainstay and laparoscopic surgery is a valid alternative.

CONCLUSION

In case of abdominal bleeding mass in a NF1 patient, it is important to keep in mind the well-known association between NF1 and GIST to facilitate the diagnosis and to quickly perform the appropriate treatment. Laparoscopic approach is safe and effective if the oncological radicality is respected.

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.

Sunitinib malate inhibits intestinal tumor development in male ApcMin/+ mice by down-regulating inflammation-related factors with suppressing β-cateinin/c-Myc pathway and re-balancing Bcl-6 and Caspase-3

Sunitinib is a tyrosine kinase inhibitor for many tumors. Inflammation is one of the most important factors in the development of intestinal tumors. Many inflammation-related factors are regulated by tyrosine kinase receptors. It is reasonable to hypothesize that sunitinib can regulate the development of intestinal tumors by regulating the expression and/or activity of inflammation-related factors. Here, ApcMin/+ male mouse model was used to investigate the effect and mechanism of sunitinib malate against intestinal cancer. Results show that compared to vehicle, after sunitinib malate treatment, overall survival of ApcMin/+ mice was lengthened up to 25 days, with a gain of body weight, reduction of spleen/body weight index, and RBC, WBC and HGC regulated to normal levels of wild type mice, and a number of polyps no less than 1 mm significantly reduced. Meanwhile, in the intestines, the nuclear β-Catenin protein and c-Myc mRNA were both down-regulated, and Bcl-6 was significantly reduced with Caspase-3 up regulated. Furthermore, inflammation-related factors including IL-6, TNF-α, IL-1α, IL-1β and IFN-γ were down-regulated at mRNA levels in the intestines. These results suggest that sunitinib malate can significantly improve the survival status and inhibit intestinal tumor development in male ApcMin/+ mice, through inhibiting inflammation-related factors, while suppressing β-cateinin/c-Myc pathway and re-balancing protein levels of Bcl-6 and Caspase-3.

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.

Comprehensive targeted next-generation sequencing approach in the molecular diagnosis of gastrointestinal stromal tumor

Mutational analysis guides therapeutic decision making in patients with advanced-stage gastrointestinal stromal tumors (GISTs). We evaluated three targeted next-generation sequencing (NGS) assays, consecutively used over 4 years in our laboratory for mutational analysis of 162 primary GISTs: Agilent GIST MASTR, Illumina TruSight 26 and an in-house developed 96 gene panels. In addition, we investigated the feasibility of a more comprehensive approach by adding targeted RNA sequencing (Archer FusionPlex, 11 genes) in an attempt to reduce the number of Wild Type GISTs. We found KIT or PDGFRA mutations in 149 out of 162 GISTs (92.0%). Challenging KIT exon 11 alterations were initially missed by different assays in seven GISTs and typically represented deletions at the KIT intron 10-exon 11 boundary or large insertions/deletions (>24 base pairs). Comprehensive analysis led to the additional identification of driver alterations in 8/162 GISTs (4.9%): apart from BRAF and SDHA mutations (one case each), we found five GISTs harboring somatic neurofibromatosis type 1 (NF1) alterations (3.1%) and one case with an in-frame TRIM4-BRAF fusion not reported in GIST before. Eventually, no driver alteration was found in two out of 162 GISTs (1.2%) and three samples (1.9%) failed analysis. Our study shows that a comprehensive targeted NGS approach is feasible for routine mutational analysis of GIST, thereby substantially reducing the number of Wild Type GISTs, and highlights the need to optimize assays for challenging KIT exon 11 alterations.

Surgical management of vertebral metastatic gastrointestinal stromal tumor: Case illustration, literature review, and pooled analysis

Background:

Gastrointestinal stromal tumors (GISTs) very rarely metastasize to the vertebrae. Tyrosine kinase inhibitors (TKIs) confer favorable long-term survival and durable disease control for metastatic disease. Here, we reviewed a case and the literature to determine the various management options, and neurological outcomes for these patients.

Case Description:

A 63-year-old Chinese female with metastatic jejunal GIST previously treated with various TKIs presented with the left lower limb weakness and a sensory level at T10. MRI revealed a T9 vertebral body tumor with cord compression. The tumor was excised and surgical fixation was performed. She received 30Gy of fractionated adjuvant radiotherapy. She achieved near-complete neurological recovery but died 2 months later from systemic disease progression.

Conclusion:

Based on this case and a review of the literature, surgical intervention and treatment with TKIs with adjuvant RT can lead to comparable survival and neurological outcomes.

Comparison of endoscopic versus laparoscopic resection for gastric gastrointestinal stromal tumors: A preliminary meta-analysis

BACKGROUND AND AIM

For localized disease, complete surgical resection is regarded as the "gold standard" therapeutic modality. With the rapid development of endoscopic techniques, endoscopic resection (ESR) has been confirmed as an efficient and safe alternative for the treatment of gastrointestinal stromal tumors (GISTs) in the stomach. Nevertheless, the management of gastric GISTs remains poorly defined. The purpose of this study is to evaluate the security and effectiveness of ESR with laparoscopic resection (LAR) for gastric GISTs.

METHODS

A literature search of online databases was conducted to identify relevant comparative studies of ESR and LAR procedures for gastric GISTs published before April 10, 2020. The cumulative data analysis was also performed utilizing the software STATA.

RESULTS

In total, 10 studies involving 1165 patients met the inclusion criteria for analysis (651 for ESR and 514 for LAR). From the results of meta-analysis, patients who underwent ESR experienced decreased operative time (P = 0.000), less intraoperative blood loss (P = 0.002), earlier time to diet (P = 0.000), shorter hospital stay (P = 0.000), and lower total charges (P = 0.000) compared with LAR. Moreover, there were no significant differences between these two approaches concerning tumor rupture, conversion rate to other procedure, complete resection rate, postoperative complication rate, recurrence rate, and disease-free survival.

CONCLUSIONS

Endoscopic resection, as an effective alternative treatment strategy with satisfactory outcomes, is acceptable for selective patients with gastric GISTs compared with LAR. Further well-designed randomized controlled trials with large samples are warranted to corroborate our observations.

Gastric Calcifying Fibrous Tumor: An Easy Misdiagnosis as Gastrointestinal Stromal Tumor-A Systemic Review

Background and Objectives: Calcifying fibrous tumor (CFT) in the stomach is extremely rare and is easily misdiagnosed as a gastrointestinal stromal tumor (GIST). This study aims to determine the best method to differentiate between gastric CFT and GIST after a systemic review and meta-analysis. Materials and Methods: A systematic search of articles using electronic databases (MEDLINE, EMBASE, and LILACS) was conducted and resulted in 162 articles with 272 CFT cases published from January 1988 to September 2019. Results: Of these cases, 272 patients, 60 patients with gastric CFT (32 men and 28 women, mean age 49.2 years) were analyzed. The mean tumor size was 2.4 cm in patients with gastric CFT. Both endoscopic ultrasound (EUS) and computed tomography (CT) findings revealed well-defined (100% vs. 77.8%), heterogeneous (100% vs. 77.8%), iso-hypoechoic (71.4% vs. 33.3%), and calcified (85.7% vs. 77.8%) lesions, respectively. The majority of patients (53.3%) were symptomatic, with the most common symptom being abdominal discomfort (55.6%). None of the patients with gastric CFT showed recurrence after treatment, and most patients received nonendoscopic treatment (56%, n = 28/50). Both age and tumor size were statistically significant in patients with gastric CFT than GIST (49.2 vs. 65.0 years and 2.4 vs. 6.0 cm; both p < 0.001). The ratio of children among patients with CFT (5%) and GIST (0.05%) was also significantly different (p = 0.037). The calcification rates of gastric CFT had significantly higher calcification rates than GIST on images of EUS and CT (85.7% vs. 3.6% and 77.8% vs. 3.6%; both p < 0.001). Conclusions: Compared with patients with GIST, patients with gastric CFT were younger, had smaller tumor size, and were symptomatic. Furthermore, gastric CFT was well-defined, heterogeneous in the third layer, and had high calcification rates on the images.

Therapeutic Potential of PI3K/AKT/mTOR Pathway in Gastrointestinal Stromal Tumors: Rationale and Progress

Simple Summary

Most gastrointestinal stromal tumors (GISTs) arise due to gain-of-function mutations of KIT and PDGFRA, encoding the receptor tyrosine kinase (RTK). The introduction of the RTK inhibitor imatinib has significantly improved the management of GISTs; however, drug resistance remains a challenge. Constitutive autophosphorylation of RTKs is associated with the activation of the PI3K/AKT/mTOR pathway. Especially, this pathway plays a pivotal role in mRNA translation initiation, directly regulated by eukaryotic initiation factors (eIFs). This review highlights the progress for targeting PI3K/AKT/mTOR-dependent mechanisms in GISTs and explores the relationship between mTOR downstream eIFs and the development of GISTs, which may be a promising future therapeutic target for this tumor entity.

Abstract

Gastrointestinal stromal tumor (GIST) originates from interstitial cells of Cajal (ICCs) in the myenteric plexus of the gastrointestinal tract. Most GISTs arise due to mutations of KIT and PDGFRA gene activation, encoding the receptor tyrosine kinase (RTK). The clinical use of the RTK inhibitor imatinib has significantly improved the management of GIST patients; however, imatinib resistance remains a challenge. The phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway is a critical survival pathway for cell proliferation, apoptosis, autophagy and translation in neoplasms. Constitutive autophosphorylation of RTKs has an impact on the activation of the PI3K/AKT/mTOR pathway. In several preclinical and early-stage clinical trials PI3K/AKT/mTOR signaling inhibition has been considered as a promising targeted therapy strategy for GISTs. Various inhibitory drugs targeting different parts of the PI3K/AKT/mTOR pathway are currently being investigated in phase Ι and phase ΙΙ clinical trials. This review highlights the progress for PI3K/AKT/mTOR-dependent mechanisms in GISTs, and explores the relationship between mTOR downstream signals, in particular, eukaryotic initiation factors (eIFs) and the development of GISTs, which may be instrumental for identifying novel therapeutic targets.

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.

Skin Metastasis of Gastrointestinal Stromal Tumors: A Case Series and Literature Review

Background

Gastrointestinal stromal tumors (GISTs) extremely and rarely metastasize to the skin, and such metastases have not been well characterized.

Methods

Retrospective analysis of clinicopathological data of patients with skin metastasis of a GIST (SM-GIST) admitted to Xiangya Hospital (Changsha, Hunan, China) and literature review were conducted.

Results

Including our 4 cases, a total of 17 cases have been reported to date. The mean age of the patients was 55.4 years (29~70 years) and there was not sex predominance (male 10 and female 7). Primary tumors were often located in the stomach (n=9), duodenum (n=2) and small bowel (n=2). Meanwhile, SM-GIST mainly occurred in head and face (n=6), extremities (n=6), followed by abdomen wall (n=5), back (n=3) and chest (n=2). Mutation analysis revealed that the frequency of wild-type GIST (WT-GIST), exon 9, 11 and 13 mutations was 6, 1, 4 and 1, respectively. The average time to SM-GIST was 4.22 years, specifically 4.59 years in gastric and 3.8 years in non-gastric. Moreover, for the resection only group (including chemotherapy), such average time was 3.63 years, while for the combined group (resection and tyrosine kinase inhibitors (TKIs)), it was about 4.74 years. The mean survival was approximately 6.2 years. However, after the diagnosis of SM-GIST, survival was only about 1.69 years.

Conclusion

SM-GIST is a rare malignant condition. Non-gastric GIST, surgery without TKIs, high invasiveness and tumor burden, and molecular subtype (mutation in exon 9, 11 and wild-type) may be conducive to the development of SM-GIST. Additionally, it is also a sign of poor prognosis.

Prognostic Value of Fibrinogen and Lymphocyte Count in Intermediate and High Risk Gastrointestinal Stromal Tumors

Purpose

Data about the prognostic value of fibrinogen concentration and absolute lymphocyte count for the prognosis of gastrointestinal stromal tumors (GISTs) were limited. Thus, the aim of the present study was to investigate the predictive value of preoperative fibrinogen concentration and absolute lymphocyte count in GISTs.

Patients and Methods

From March 2002 to December 2017, 143 intermediate and high risk GIST patients treated with R0 resection were enrolled in the present study. Clinicopathological characteristics were recorded. The optimal cut-off values of patients were calculated by X-tile software. Categorical variables were analyzed using Chi-square test or Fisher's exact test. Disease-free survival was analyzed by the Kaplan-Meier method and compared by a Log rank test.

Results

There were 71 males (49.65%) and 72 females. The median age was 56 years (range 19-86). The optimal cut-off value was 4.5 g/L for fibrinogen concentration (P=0.000) and 1.0×10⁹/L for lymphocyte count (P=0.002). No significant association was found between lymphocyte level and clinicopathological features. However, elevated fibrinogen level was correlated with tumor location, tumor size and NIH risk category. Tumor size, fibrinogen concentration and lymphocyte count were independent risk factors for the prognosis of patients according to the multivariate analysis. The prognosis of patients with high fibrinogen concentration or low lymphocyte count was significantly worse than that with low fibrinogen concentration or high lymphocyte count. Further, combination of fibrinogen concentration and lymphocyte count could increase the prognostic value for GIST patients.

Conclusion

Fibrinogen concentration and absolute lymphocyte count were independent prognostic factors for intermediate and high risk GIST patients. The combination of fibrinogen concentration and absolute lymphocyte count could further increase the predictive value for the prognosis of GIST patients.

Succinate dehydrogenase-deficient gastrointestinal stromal tumor of stomach diagnosed by endoscopic ultrasound-guided fine-needle biopsy: Report of a distinct subtype in cytology

Succinate dehydrogenase (SDH)-deficient gastrointestinal stromal tumors (GISTs) are characterized by the lack of mutations in KIT receptor tyrosine kinase complex and platelet derived growth factor receptor-alpha (PDGFRA) that are commonly found in the majority of GISTs. SDH-deficient GISTs comprise approximately 5%-10% of all GISTs. This subset may be associated with Carney Triad and Carney-Stratakis syndrome. SDH-deficient GISTs show unique demographic, radiologic, morphologic findings, clinical behavior, and treatment response. To our knowledge, the identification and characterization of this subset of GISTs have not yet been described in the cytopathology literature. By understanding the clinical as well as the other unique features of this tumor, in addition to the rapidly evolving identification of specific molecular alterations and targeted therapies, cytopathologists may play an important role in the diagnosis and work-up of these patients to allow clinicians to better manage and treat them. We present a young female with gastric SDH-deficient GIST diagnosed by fine-needle biopsy with supporting surgical pathology follow-up and molecular confirmation. This report suggests that the diagnosis of SDH-deficient GIST can be made on cytology in the appropriate clinical setting by using cytomorphologic features and demonstrating SDH loss by IHC on the cell block. In addition, molecular testing may be possible on the cytology cell block or supernatant to confirm the diagnosis.

Spectrum of activity of dasatinib against mutant KIT kinases associated with drug-sensitive and drug-resistant gastrointestinal stromal tumors

BACKGROUND

The majority of GISTs express mutationally activated KIT. Imatinib and sunitinib are approved KIT-inhibiting therapies. Their efficacy is usually hampered by the acquired multiple secondary drug-resistance KIT mutations. The most problematic resistance subset is GISTs with acquisition of secondary mutations in the KIT activation loop. Here, we establish the spectrum of activity of dasatinib against a comprehensive collection of clinically relevant KIT mutants associated with drug-sensitive and drug-resistant GIST.

METHODS

The cellular and in vitro activities of tyrosine kinase inhibitors (TKIs) against mutant KIT were assessed using a panel of engineered and GIST-derived cell lines. The in vivo activities of dasatinib were determined using TKI-resistant xenograft models.

RESULTS

In engineered and GIST-derived cell lines, dasatinib potently inhibited KIT with primary mutations in exon 11 or 9 and a range of secondary imatinib-resistant mutations in exons 13 and 14, encoding the ATP-binding pocket, and in exons 17 and 18, encoding the activation loop, with the exception of a substitution at codon T670. Our data show that dasatinib is more potent than imatinib or sunitinib at inhibiting the activity of drug-resistant KIT mutants. Dasatinib also induces regression in GIST-derived xenograft models containing these secondary mutations. A major determinant of the efficacy of dasatinib for the treatment of advanced GIST is the activity of this inhibitor against KIT mutants.

CONCLUSION

Dasatinib shows efficacy in cancer models, inhibiting a wide range of oncogenic primary and drug-resistant KIT mutants. These results have implications for the further development of dasatinib precision therapy in GIST patients.

Endoscopic or Surgical Resection for Patients with 2-5cm Gastric Gastrointestinal Stromal Tumors: A Single-Center 12-Year Experience from China

Purpose

The surgical or endoscopic resection is the current treatment modality for 2–5 cm gastric gastrointestinal stromal tumors (GISTs). However, evidence is lacking as to which treatment modality is better. Our objective is to provide a new reference for the standardization of the treatment of 2–5 cm gastric GISTs.

Patients and Methods

A retrospective study was conducted on 177 patients who underwent resection for 2–5cm gastric GISTs between January 2007 and July 2019 at Xiangya Hospital of Central South University. The cases were divided into surgical group (n=118) and endoscopic group (n=59). The clinical data, pathological and genetic characteristics, short- and long-term outcomes were compared.

Results

Symptoms showed more obvious in the surgical group including abdominal pain and bleeding. In the endoscopic group, tumor size was smaller (p<0.001), and risk classification was lower (p<0.001). Patients in the endoscopic group had shorter anal exhaust time (p<0.001) and lesser hospital cost (p<0.001). However, the incidence rate of complications (25.42 vs 4.20%; p<0.001) and reoperation (22.03 vs 0.00%; p<0.001) in the endoscopic group was relatively higher than these in the surgical group. There was no significant difference in recurrence-free survival or overall survival between two groups.

Conclusion

Gastric GISTs of 2–5cm may be suitable to select laparoscopic surgery.

Fibrinogen/Albumin Ratio Index Is an Independent Prognosis Predictor of Recurrence-Free Survival in Patients After Surgical Resection of Gastrointestinal Stromal Tumors

Background: Nutritional status, systemic inflammation, and coagulation mechanism are closely related to tumor progression. Herein, we examined the role of fibrinogen-to-albumin ratio index (FARI) in the prognosis of gastrointestinal stromal tumors (GISTs) and developed a novel nomogram predicting recurrence-free survival (RFS).

Methods: We retrospectively analyzed data from 357 GIST patients admitted at the gastrointestinal surgery of the Beijing Hospital from January 2008 to January 2018 and underwent curative resection. FARI was calculated as fibrinogen level (g/L) /albumin level (g/L). The cutoff point of FARI was set using the point with the largest Youden index on the receiver operating characteristic curve with the 5-years recurrence-free survival as an endpoint. We used the Kaplan-Meier approach and multivariable Cox regression model to study the impact of FARI on recurrence-free survival. Finally, we developed a nomogram based on tumor size, location, mitotic index, and FARI to predict RFS. The nomogram was assessed by calculating concordance probabilities and testing calibration of predicted RFS with observed RFS. Concordance probabilities were also compared with the National Institute of Health (NIH) risk classification system.

Results: The ROC curve revealed that the best cutoff point of the FARI was set as 0.08. The patients were classified into the FARI-high (≥0.08) and FARI-low (<0.08) groups. FARI was significantly associated with age, size of the tumor, NIH risk category, and Mitotic Index (all P < 0.05). FARI was weakly associated with NLR and PLR. FARI and PNI had a weak negative association. Multivariate analysis showed that the NIH risk category and FARI were independent prognostic predictors for worse outcomes concerning RFS in GIST patients. In the high-risk subgroup, patients with low FARI also had a more prolonged RFS than patients with high FARI (P < 0.05). The nomogram had a concordance probability of 0.802 (SE 0.025). Nomogram predictions were well-calibrated. Concordance probabilities of the nomogram were better than NIH risk classification system [0.802 [0.025] vs. 0.737 [0.024], p < 0.01].

Conclusion: We established that preoperative FARI is a novel serum biomarker to predict the prognosis after surgical resection of GISTs. The nomogram incorporating FARI could be used to help the decision-making of clinical treatment.

Laparoscopic Versus Open Surgery for Gastric Gastrointestinal Stromal Tumors: a Propensity Score Matching Analysis

BACKGROUND

Surgery is the first choice for the treatment of gastric gastrointestinal stromal tumors (GISTs). With the development of new instruments and techniques, the popularity of laparoscopic resection of GISTs has increased rapidly. Previous studies on the advantages of laparoscopic resection over open surgery are generally limited by methodology or data capacity. This study evaluated the efficacy of laparoscopic resection and open surgery in gastric GISTs using the propensity score matching (PSM) method.

METHODS

Between January 2005 and December 2017, 1027 patients were diagnosed with primary GIST at our institution. Among them, 548 patients were enrolled in this study. Standard demographic and clinicopathological data were collected from our database. Selection bias was eliminated using the PSM methods.

RESULTS

After PSM, 256 cases involved in the comparison (128 laparoscopic (LAP) vs. 128 open surgery (OPEN)) were randomly matched (1:1) by age, sex, body mass index, hypertension, diabetes, heart disease, year of surgery, tumor location, tumor size, mitotic rate, and treatment with adjuvant tyrosine kinase inhibitors. The LAP group was superior to the OPEN group in blood loss (χ² = 6.048, P = 0.049), time to first flatus (49.41 ± 7.56 vs. 71.31 ± 4.87 h, P < 0.001), and hospital stay (10.21 ± 6.05 vs. 12.56 ± 5.43 days, P = 0.001). No significant differences were seen in either the relapse-free survival or overall survival between the LAP and OPEN groups. In tumors located in favorable locations, the LAP group showed less blood loss (P = 0.008) and less multivisceral resection (17.8% vs. 5.5%, P = 0.02).

CONCLUSIONS

Laparoscopic resection for gastric GISTs is associated with improved surgical outcomes and postoperative courses and comparable oncological outcomes, regardless of favorable or unfavorable tumor location.

Positron Emission Tomography-Based Response to Target and Immunotherapies in Oncology

2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG) is a promising tool to support the evaluation of response to either target therapies or immunotherapy with immune checkpoint inhibitors both in clinical trials and, in selected patients, at the single patient's level. The present review aims to discuss available evidence related to the use of [¹⁸F]FDG PET (Positron Emission Tomography) to evaluate the response to target therapies and immune checkpoint inhibitors. Criteria proposed for the standardization of the definition of the PET-based response and complementary value with respect to morphological imaging are commented on. The use of PET-based assessment of the response through metabolic pathways other than glucose metabolism is also relevant in the framework of personalized cancer treatment. A brief discussion of the preliminary evidence for the use of non-FDG PET tracers in the evaluation of the response to new therapies is also provided.

An Unexpected Response to Imatinib in a "Wild-Type" Gastrointestinal Stromal Tumor

INTRODUCTION

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract and the most frequent sarcomas in some geographic regions. In patients with metastatic GIST, the tyrosine kinase inhibitor imatinib is the first-line standard of care. Mutations in KIT or specific platelet-derived growth factor receptor alpha (PDGFRA) gene aberrations in the tumor cells predict a favorable response to this agent, while tumors without KIT or PDGFRA mutations ("wild-type" GISTs) are usually resistant to such treatment. Next-generation sequencing (NGS) is commonly used for mutational analysis of GISTs.

CASE PRESENTATION

We present a case of an unexpected response to imatinib treatment in a GIST that was initially called "wild-type" based on routine NGS. A spectacular response to empirical imatinib treatment triggered further genetic analysis and led to the identification of a 45-bp duplication in KIT exon 11 undetectable by routine NGS.

CONCLUSION

Negative findings on routine NGS testing for KIT alterations do not exclude the presence of actionable drug targets, as in the case of larger or complex gene insertions or deletions. Updating the NGS bioinformatics pipeline to ensure identification of larger deletions or insertions or additional Sanger sequencing is warranted in NGS driver-negative GISTs in order to allow accurate detection of actionable mutations.

Chloroquine Combined with Imatinib Overcomes Imatinib Resistance in Gastrointestinal Stromal Tumors by Inhibiting Autophagy via the MAPK/ERK Pathway

Background

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. However, up to 40–50% of GISTs develop secondary resistance after an average of 24 months of imatinib treatment. It has been reported that autophagy can promote the survival of GIST cells and induce drug resistance. Presently, the specific mechanism of autophagy in GISTs with imatinib resistance is not clear.

Materials and Methods

The cell-counting kit (CCK)-8 method and flow cytometry were used for in vitro drug sensitivity testing and autophagy level detection. Detection of the apoptosis level was by flow cytometry with the annexin V Kit. Western blotting was used to analyze the role of autophagy and apoptosis in GIST cells with CQ alone, imatinib alone, or in combination, and to analyze MAPK pathway expression. In vitro results were confirmed by in vivo experiments using the mice model. Hematoxylin and eosin and immunohistochemical staining were used to detect the pathological characteristics and immunophenotype of the transplanted tumor. Detection of KIT and PDGFRA gene mutations in the transplanted imatinib-resistant GIST was done by denaturing high performance liquid chromatography (DHPLC) and direct sequencing. ERK and KIT expression and regulation levels were detected by Western blotting.

Results

In vitro and vivo experiments, the autophagy level of imatinib-resistant cells was higher than that of normal cells; CQ combined with imatinib can promote apoptosis by blocking autophagy of imatinib-resistant cells. In the meanwhile, we found that the phosphorylation level of ERK may be related to autophagy.

Conclusion

Our data suggest that autophagy through the MAPK/ERK pathway may play a pivotal role in imatinib-resistant GIST proliferation. Moreover, combining an autophagy inhibitor with imatinib may be a potential valuable strategy in overcoming acquired resistance in GIST patients.

Prognostic Indicators for Gastrointestinal Stromal Tumors: A Review

Gastrointestinal stromal tumors (GISTs) are potentially malignancies that can occur anywhere in the digestive tract. Tyrosine kinase inhibitors (TKIs) such as imatinib have proven effective since the discovery of KIT and PDGFRA. The current version of NCNN, ESMO and EURACAN guidelines recognized that the three main prognostic factors are the mitotic rate, tumor size and tumor site. In addition, tumor rupture is also recognized as an independent risk factor. However, recent evidence shows that various types of gene mutations are associated with prognosis, and influencing factors such as gastrointestinal bleeding and high Ki67 index have been associated with poor prognosis. It shows that the current risk classification is still insufficient and controversial. With the emergence of more and more lack mutation in KIT/PDGFRA GISTs (KIT/PDGFRA wild-type GISTs) or drug resistance genes, primary and secondary drug resistance problems are caused, which makes the treatment of late or metastatic GIST face challenges. Therefore, this article will review the clinicopathological characteristics of GIST, the special molecular subtypes and other factors that may affect prognosis. We will also explore reliable prognostic markers for better postoperative management and improve the prognosis of patients with GIST.

Germline SDHB-inactivating mutation in gastric spindle cell sarcoma

Gastrointestinal stromal tumors (GISTs) are the most frequent mesenchymal tumors of the gastrointestinal tract. Inactivating mutations or epigenetic deregulation of succinate dehydrogenase complex (SDH) genes are considered defining features of a subset of GIST occurring in the stomach. Based on comprehensive molecular profiling and biochemical analysis within a precision oncology program, we identified hallmarks of SDH deficiency (germline SDHB-inactivating mutation accompanied by somatic loss of heterozygosity, lack of SDHB expression, global DNA hypermethylation, and elevated succinate/fumarate ratio) in a 40-year-old woman with undifferentiated gastric spindle cell sarcoma that did not meet the diagnostic criteria for other mesenchymal tumors of the stomach, including GIST. These data reveal that the loss of SDH function can be involved in the pathogenesis of non-GIST sarcoma of the gastrointestinal tract.

Prognostic significance of preoperative plasma fibrinogen levels in primary gastrointestinal stromal tumours: a retrospective cohort study

BACKGROUND

Improved prediction of prognosis for gastrointestinal stromal tumours (GISTs) has become increasingly important since the introduction of targeted therapy. Here, we aimed to evaluate the prognostic significance of preoperative plasma fibrinogen (Fib) levels in patients with primary GISTs and to analyse their correlations with clinicopathological characteristics.

METHODS

A total of 201 previously untreated patients with primary GISTs who had undergone radical surgery at our institution between October 2004 and July 2018 were enrolled. The optimal cut-off value for Fib levels was calculated using time-dependent receiver-operating characteristic curve analysis. RFS, the primary endpoint, was calculated by the Kaplan-Meier method and compared by the log-rank test. Univariate and multivariate Cox regression models were calculated.

RESULTS

High preoperative plasma Fib levels were detected as an independent adverse prognostic factor (p = 0.008, hazard ratio 3.136, 95% CI 1.356‒7.256). Furthermore, high preoperative plasma Fib levels also indicated a poor prognosis within the modified National Institutes of Health (mNIH) high-risk subgroup (p = 0.041). In addition, preoperative plasma Fib levels showed a positive correlation with several prognostic factors and even a linear relationship with tumour size (Spearman correlation coefficient [r] = 0.411, p < 0.001).

CONCLUSIONS

Our results suggest that high preoperative plasma Fib levels may indicate a poor prognosis in patients with primary GISTs. As a cost-effective biomarker, preoperative assessment of plasma Fib levels may help to further risk stratify patients with mNIH high-risk GISTs and instruct the application of targeted therapy.

Long-term survival among patients with gastrointestinal stromal tumors diagnosed after another malignancy: a SEER population-based study

Background

To explore overall survival (OS) and GISTs-specific survival (GSS) among cancer survivors developing a second primary gastrointestinal stromal tumors (GISTs).

Methods

We conducted a cohort study, where patients with GISTs after another malignancy (AM-GISTs, n = 851) and those with only GISTs (GISTs-1, n = 7660) were identified from the Surveillance, Epidemiology, and End Results registries (1988–2016). Clinicopathologic characteristics and survival were compared between the two groups.

Results

The most commonly diagnosed first primary malignancy was prostate cancer (27.7%), followed by breast cancer (16.2%). OS among AM-GISTs was significantly inferior to that of GISTs-1; 10-year OS was 40.3% vs. 50.0%, (p < 0.001). A contrary finding was observed for GSS (10-year GSS 68.9% vs. 61.8%, p = 0.002). In the AM-GISTs group, a total of 338 patients died, of which 26.0% died of their initial cancer and 40.8% died of GISTs. Independent of demographics and clinicopathological characteristics, mortality from GISTs among AM-GISTs patients was decreased compared with their GISTs-1 counterparts (HR, 0.71; 95% CI, 0.59–0.84; p < 0.001), whereas OS was inferior among AM-GISTs (HR, 1.11; 95% CI, 0.99–1.25; p = 0.085).

Conclusions

AM-GISTs patients have decreased risk of dying from GISTs compared with GIST-1. Although another malignancy history does not seemingly affect OS for GISTs patients, clinical treatment of such patients should be cautious.

Retrospective Analysis of Chilean and Mexican GI Stromal Tumor Registries: A Tale of Two Latin American Realities

PURPOSE

Like other malignancies, GI stromal tumors (GIST) are highly heterogeneous. This not only applies to histologic features and malignant potential, but also to geographic incidence rates. Several studies have reported GIST incidence and prevalence in Europe and North America. In contrast, GIST incidence rates in South America are largely unknown, and only a few studies have reported GIST prevalence in Latin America.

PATIENTS AND METHODS

Our study was part of a collaborative effort between Chile and Mexico, called Salud con Datos. We sought to determine GIST prevalence and patients' clinical characteristics, including survival rates, through retrospective analysis.

RESULTS

Overall, 624 patients were included in our study. Our results found significant differences between Mexican and Chilean registries, such as stage at diagnosis, primary tumor location, CD117-positive immunohistochemistry status, mitotic index, and tumor size. Overall survival (OS) times for Chilean and Mexican patients with GIST were 134 and 156 months, respectively. No statistically significant differences in OS were detected by sex, age, stage at diagnosis, or recurrence status in both cohorts. As expected, patients categorized as being at high risk of recurrence displayed a trend toward poorer progression-free survival in both registries.

CONCLUSION

To the best of our knowledge, this is the largest report from Latin America assessing the prevalence, clinical characteristics, postsurgery risk of recurrence, and outcomes of patients with GIST. Our data confirm surgery as the standard treatment of localized disease and confirm a poorer prognosis in patients with regional or distant disease. Finally, observed differences between registries could be a result of registration bias.

Linsitinib (OSI-906) for the Treatment of Adult and Pediatric Wild-Type Gastrointestinal Stromal Tumors, a SARC Phase II Study

PURPOSE

Most gastrointestinal stromal tumors (GIST) have activating mutations of KIT, PDGFRA, or uncommonly BRAF. Fifteen percent of adult and 85% of pediatric GISTs are wild type (WT), commonly having high expression of IGF-1R and loss of succinate dehydrogenase (SDH) complex function. We tested the efficacy of linsitinib, an oral TKI IGF-1R inhibitor, in patients with WT GIST.

PATIENTS AND METHODS

A multicenter phase II trial of linsitinib was conducted. The primary endpoint was objective response rate. Secondary endpoints were clinical benefit rate: complete response, partial response, and stable disease (SD) ≥ 9 months, and quantitative 2[18F]fluoro-2-deoxy-D-glucose (FDG) metabolic response (MR) at week 8. Serum levels for glucose, insulin, IGF-1R ligand IGF1, and binding proteins were obtained to explore correlations to patient outcomes and FDG-PET results.

RESULTS

Twenty patients were accrued in a 6-month period. Grade 3-4 toxicities possibly related to linsitinib were uncommon (8.5%). No objective responses were seen. Clinical benefit rate (CBR) at 9 months was 40%. Intense FDG uptake was observed at baseline, with partial MR of 12% and stable metabolic disease of 65% at week 8; these patients had RECIST 1.1 SD as their best response. Progression-free survival (PFS) and overall survival Kaplan-Meier estimates at 9 months were 52% and 80%, respectively. SDHA/B loss determined by IHC was seen in 35% and 88% of cases, respectively.

CONCLUSIONS

Linsitinib is well tolerated in patients with WT GIST. Although the 9-month CBR was 40%, and PFS at 9 months was 52%, no objective responses were observed. Rapid accrual to this study demonstrates that clinical trials of experimental agents in selected subtypes of GIST are feasible.

Correlations between imatinib plasma trough concentration and adverse reactions in Chinese patients with gastrointestinal stromal tumors

BACKGROUND

Imatinib is the standard treatment for patients with gastrointestinal stromal tumors (GISTs), but there is significant variation in imatinib plasma trough concentrations (C_min ) among patients. The imatinib C_min distribution at different doses and the correlation of adverse reactions with C_min in Chinese patients with GIST from a high-volume center were evaluated.

METHODS

From July 1, 2017 to December 31, 2018, patients who were receiving imatinib treatment for GIST were prospectively enrolled. Steady-state blood samples were obtained from patients who had received same-dose imatinib treatment for ≥1 month with good compliance. Adverse reactions were recorded during regular follow-up, and blood samples were collected 24 ± 2 hours after dosing. Liquid chromatography-tandem mass spectrometry was used to measure drug concentrations.

RESULTS

In total, 307 patients who received 367 dose levels were investigated. The imatinib C_min was 1315 ± 716 ng/mL, 2117 ± 597 ng/mL, and 3844 ± 987 ng/mL in patients who were receiving imatinib 400 mg, 600 mg, and 800 mg daily, respectively. The C_min was significantly correlated with periorbital and limb edema (P < .001), anemia (P < .001), and rash (P = .037). Nausea and vomiting, diarrhea, and conjunctival hemorrhage also were correlated, but not significantly. A much higher C_min was observed with severe adverse reactions. There was no correlation between the imatinib C_min and leukopenia, muscle cramps, or hepatobiliary dysfunction.

CONCLUSIONS

In Chinese patients with GIST, the imatinib C_min was higher than that reported for Western populations, especially at higher doses. The C_min was correlated with periorbital and limb edema, anemia, and rash, suggesting that monitoring the imatinib C_min should be considered when patients develop severe adverse reactions caused by excessive imatinib plasma concentrations.

Pharmacogenomics Biomarkers of Soft Tissue Sarcoma Therapies

Soft tissue sarcomas (STS) are heterogeneous rare malignancies comprising ~1% of all solid cancers in adults and including more than 70 histological and molecular subtypes with different pathological and clinical development characteristics. Over the last two decades, the increased knowledge of the new molecular and genomic mechanisms of different STS histotypes allowed for a reclassification of these tumors and consequently to the development of novel chemotherapeutic agents. Generally, surgery, in combination with radiotherapy only in selected cases of localized disease, represents the most common treatment of primary STS, whereas the principal treatment modality for locally advanced or metastatic disease is first-line chemotherapy. The principal treatment for the preponderance of STS patients is usually an anthracycline (epirubicin and doxorubicin) in monotherapy or in combination with other drug novel chemotherapeutic agents. However, survival for treated patients with metastatic disease is poor, and a 2-years survival rate is about 30%. In this scenario, Pharmacogenomics (PGx) biomarkers that can predict drug response play an important role in the improvement of molecular diagnostics in clinical routines and contribute to elucidating the genetic basis for the differences in treatment efficacy and toxicity among STS patients. This review focuses on recent insight in the PGx biomarkers that have been described to modulate responsiveness and toxicity parameters of conventional and new chemotherapeutics drugs in several STS histotypes.

Progress in determining response to treatment in gastrointestinal stromal tumor

Introduction: Gastrointestinal stromal tumor (GIST) is the most common malignant mesenchymal tumor of the gastrointestinal system. Multiple advances in the management of GIST from the discovery of KIT/PDGRA and other genetic alterations have led to the development of multiple tyrosine kinase inhibitors. Response assessment in GIST is determined with iRECIST (Response Evaluation Criteria in Solid Tumors), PERCIST (PET response criteria in solid tumors), or Choi criteria. Molecular genotyping of the tissue samples is the recent standard for diagnosis, treatment, and response to treatment.Areas covered: In this study, we provide a brief overview of the history of the GIST, molecular sequencing, available treatment options and clinical trials, radiologic response assessment, and the role of ctDNA in response evaluation.Expert opinion: Future GIST management is related to the development of sensitive assays to detect genetic alterations for initial diagnosis, treatment selection, monitoring the response to treatment, resistant mutations, and predicting survival.