Gain-of-function mutations of c-kit in human gastrointestinal stromal tumors

Lymph Node Metastases in Gastrointestinal Stromal Tumors: an Uncommon Event

BACKGROUND

Lymph node (LN) metastases are uncommon among gastrointestinal stromal tumors (GISTs), and their presence has not been utilized in disease prognostication. This study was designed to examine factors associated with GIST nodal metastases and their impact on survival.

PATIENTS AND METHODS

Patients undergoing surgical resection of GIST with nodal evaluation were selected from the National Cancer Database. Logistic regression was utilized to evaluate factors associated with LN metastases. Survival was assessed for patients with and without nodal involvement and Cox regression was used to evaluate the impact of LN metastases while adjusting for other prognostic factors.

RESULTS

Out of 5018 patients, 301 (6.0%) had LN involvement. Nodal metastases occurred most frequently among tumors of the stomach (49.5%), followed by the small bowel (43.2%), colorectum (6.0%), and esophagus (1.3%). On multivariable analysis, male sex (OR 1.34), high mitotic rate (OR 2.10), tumor size (OR 1.02), and a primary tumor located in the small bowel (OR 1.36) were all significantly associated with nodal metastases. LN metastases were significantly associated with decreased overall survival (OS) for tumors arising in the small bowel (log-rank p < 0.01) and the colorectum (log-rank p < 0.01). Within a multivariable model adjusting for established prognostic factors, LN metastases remained independently associated with decreased survival (HR 1.60, p < 0.001).

CONCLUSIONS

For GISTs, LN metastases occur more often in males and were associated with tumor size and mitotic activity. Nodal involvement is associated with decreased survival, independent of other well-established prognostic factors.

Selective immunocapture reveals neoplastic human mast cells secrete distinct microvesicle- and exosome-like populations of KIT-containing extracellular vesicles

Activating mutations in the receptor KIT promote the dysregulated proliferation of human mast cells (huMCs). The resulting neoplastic huMCs secrete extracellular vesicles (EVs) that can transfer oncogenic KIT among other cargo into recipient cells. Despite potential contributions to diseases, KIT-containing EVs have not been thoroughly investigated. Here, we isolated and characterized KIT-EV subpopulations released by neoplastic huMCs using an immunocapture approach that selectively isolates EVs containing KIT in its proper topology. Immunocapture of EVs on KIT antibody-coated electron microscopy (EM) affinity grids allowed to assess the morphology and size of KIT-EVs. Immunoblot analysis demonstrated KIT-EVs have a distinct protein profile from KIT-depleted EVs, contain exosome and microvesicle markers, and are separated into these subtypes by ultracentrifugation. Cell treatment with sphingomyelinase inhibitors shifted the protein content among KIT-EV subtypes, suggesting different biogenesis routes. Proteomic analysis revealed huMC KIT-EVs are enriched in proteins involved in signalling, immune responses, and cell migration, suggesting diverse biological functions, and indicated neoplastic huMCs disseminate KIT via shuttling in heterogeneous microvesicle- and exosome-like EVs. Further, selective KIT-immunocapture will enable the enrichment of specific huMC-derived EVs from complex human biosamples and facilitate an understanding of their in vivo functions and potential to serve as biomarkers of specific biological pathologies.

Gastrointestinal Stromal Tumors: 10-Year Experience in Cancer Center-The Ottawa Hospital (TOH)

(1) Background: The management of gastrointestinal stromal tumors (GIST) has significantly evolved over the last two decades, with the introduction of tyrosine kinase inhibitors (TKI). We aim to report 10 years of experience of GIST management at a regional cancer center in Canada. (2) Methods: We retrospectively analyzed the records of 248 consecutive patients diagnosed with GIST between 2011 and 2021. We describe the clinical and pathological data, management, and outcome, including survival. (3) Results: The most common GIST sites were the stomach 63% (156), followed by the small bowel 29% (73). At diagnosis, 83% (206) of patients had localized disease (stage I-III). According to the modified National Institutes of Health consensus criteria (NIH) for GIST, around 45% (90) had intermediate or high-risk disease. Most patients, 86% (213), underwent curative surgical resection. Forty-nine patients received adjuvant imatinib, while forty-three patients had advanced disease and received at least one line of TKI. With a median follow-up of 47 months, the 5-year recurrence-free survival (RFS) rates for very low and low risk were 100% and 94%, respectively, while those for intermediate and high risk were 84% and 51%, respectively. The 5-year overall survival (OS) rates for very low and low risk were 100% and 94%, while intermediate, high risk, and advanced were 91%, 88%, and 65%, respectively. Using the Kaplan-Meier method, there were statistically significant differences in RFS and OS between NIH risk groups, p < 0.0005. In univariate analysis, ECOG, site, mitosis, secondary malignancy, and size were predictors for OS. High mitosis and large size (>5 cm) were associated with worse RFS. (4) Conclusions: Curative surgical resection remains the gold standard management of GIST. Our results are comparable to the reported literature. Further research is needed to explore histology's role in risk stratification and initiating adjuvant TKI.

On the Relevance of Soft Tissue Sarcomas Metabolic Landscape Mapping

Soft tissue sarcomas (STS) prognosis is disappointing, with current treatment strategies being based on a "fit for all" principle and not taking distinct sarcoma subtypes specificities and genetic/metabolic differences into consideration. The paucity of precision therapies in STS reflects the shortage of studies that seek to decipher the sarcomagenesis mechanisms. There is an urge to improve STS diagnosis precision, refine STS classification criteria, and increase the capability of identifying STS prognostic biomarkers. Single-omics and multi-omics studies may play a key role on decodifying sarcomagenesis. Metabolomics provides a singular insight, either as a single-omics approach or as part of a multi-omics strategy, into the metabolic adaptations that support sarcomagenesis. Although STS metabolome is scarcely characterized, untargeted and targeted metabolomics approaches employing different data acquisition methods such as mass spectrometry (MS), MS imaging, and nuclear magnetic resonance (NMR) spectroscopy provided important information, warranting further studies. New chromatographic, MS, NMR-based, and flow cytometry-based methods will offer opportunities to therapeutically target metabolic pathways and to monitorize the response to such metabolic targeting therapies. Here we provide a comprehensive review of STS omics applications, comprising a detailed analysis of studies focused on the metabolic landscape of these tumors.

THZ1 targeting CDK7 suppresses c-KIT transcriptional activity in gastrointestinal stromal tumours

Background

Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal tumours of the gastrointestinal tract and are characterized by activating mutations of c-KIT or PDGFRa receptor tyrosine kinases (RTKs). Despite the clinical success of tyrosine kinase inhibitors (TKIs), more than half of GIST patients develop resistance due to a second mutation. Cyclin-dependent kinase 7 (CDK7) is the catalytic subunit of CDK-activating kinase (CAK), and it plays an important role in the regulation of cell cycle transitions and gene transcription. THZ1, a CDK7 inhibitor, exhibits a dose-dependent inhibitory effect in various cancers.

Methods

Data from the public GEO database and tissue microarray were used to analyse the gene expression levels of CDKs in GISTs. The impact of CDK7 knockdown and the CDK7 inhibitor THZ1 on GIST progression was investigated in vitro using CCK-8, colony formation, and flow cytometry assays and in vivo using a xenograft mouse model. RNA sequencing was performed to investigate the mechanism of GIST cell viability impairment mediated by THZ1 treatment.

Results

Our study demonstrated that CDK7 is relatively overexpressed in high-risk GISTs and predicts a poor outcome. A low concentration of THZ1 exhibited a pronounced antineoplastic effect in GIST cells in vivo and in vitro. Moreover, THZ1 exerted synergistic anticancer effects with imatinib. THZ1 treatment resulted in transcriptional modulation by inhibiting the phosphorylation of Ser2, Ser5, and Ser7 within RNA polymerase II (RNAPII). c-KIT, an oncogene driver of GIST, was transcriptionally repressed by THZ1 treatment or CDK7 knockdown. Transcriptome sequencing analysis showed that OSR1 acts as a downstream target of CDK7 and regulates c-KIT expression. Taken together, our results highlight elevated CDK7 expression as a predictor of poor outcome in GIST and present the combination of CDK7 and RTK inhibitors as a potent therapeutic strategy to improve the efficacy of GIST treatment.

Might Patients with Metastatic Gastrointestinal Stromal Tumors Benefit from Operative Management? A Population-Based Retrospective Study

Background

With respect to effect of surgery on the therapy of patients with metastatic gastrointestinal stromal tumors (mGISTs), still no consensus has been reached. This research designed to investigate the effect of surgical treatment on prognosis in patients with mGISTs.

Methods

The population-based study consisted of 6282 GIST patients diagnosed between 2001 and 2016, from the Surveillance, Epidemiology, and End Results (SEER) database registry. The Kaplan-Meier method and Cox model were employed for the exploration of the effect of surgery on overall survival (OS) and GIST-specific survival (GSS).

Results

In total, 6282 patients were diagnosed with GISTs, including 1238 (19.7%) mGIST patients and 5044 (80.3%) non-mGIST patients. Compared with the patients with non-mGISTs, metastatic patients assumed relatively lower proportion of surgical management (756 [61.1%] vs. 4666 [92.5%], P < 0.001). Based on unadjusted analysis, mGIST patients with operative management presented higher five years OS together with GSS in comparison with those without operative management (OS: 58.3% vs. 33.1%, P < 0.001; GSS: 61.6% vs. 36.7%, P < 0.001). Multivariable analysis found that no surgery was correlated to more than 2-fold increased death risk (OS, adjusted HR = 2.27, 95% CI: 1.90-2.71; GSS, adjusted HR = 2.42, 95% CI: 2.00-2.93).

Conclusion

Metastatic GIST patients could potentially benefit from operative management with improved GSS and OS.

Advances in the research of the mechanism of secondary resistance to imatinib in gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. At present, surgery is the first-line treatment for primary resectable GISTs; however, the recurrence rate is high. Imatinib mesylate (IM) is an effective first-line drug used for the treatment of unresectable or metastatic recurrent GISTs. More than 80% of patients with GISTs show significantly improved 5-year survival after treatment; however, approximately 50% of patients develop drug resistance after 2 years of IM treatment. Therefore, an in-depth research is urgently needed to reveal the mechanisms of secondary resistance to IM in patients with GISTs and to develop new therapeutic targets and regimens to improve their long-term prognoses. In this review, research on the mechanisms of secondary resistance to IM conducted in the last 5 years is discussed and summarized from the aspects of abnormal energy metabolism, gene mutations, non-coding RNA, and key proteins. Studies have shown that different drug-resistance mechanism networks are closely linked and interconnected. However, the influence of these drug-resistance mechanisms has not been compared. The combined inhibition of drug-resistance mechanisms with IM therapy and the combined inhibition of multiple drug-resistance mechanisms are expected to become new therapeutic options in the treatment of GISTs. In addition, implementing individualized therapies based on the identification of resistance mechanisms will provide new adjuvant treatment options for patients with IM-resistant GISTs, thereby delaying the progression of GISTs. Previous studies provide theoretical support for solving the problems of drug-resistance mechanisms. However, most studies on drug-resistance mechanisms are still in the research stage. Further clinical studies are needed to confirm the safety and efficacy of the inhibition of drug-resistance mechanisms as a potential therapeutic target.

Correlation of treatment outcome in sanger/RT‑qPCR KIT/PDGFRA wild‑type metastatic gastrointestinal stromal tumors with next‑generation sequencing results: A single‑center report

In patients with gastrointestinal stromal tumors (GIST), it has become mandatory to determine the driver mutation in order to predict the response to standard treatment with tyrosine kinase inhibitors (TKI). A total of 10‑15% of all GIST lack activating mutations in KIT proto‑oncogene, receptor tyrosine kinase (KIT)/platelet‑derived growth factor receptor alpha (PDGFRA) and have been classified as KIT/PDGFRA wild‑type (WT) GIST. They are characterized by poor response to TKI. From a group of 119 metastatic GIST patients, 17 patients with KIT/PDGFRA/BRAF WT GIST as determined by reverse transcription‑quantitative (RT‑q) PCR and Sanger sequencing were profiled by a targeted next‑generation sequencing (NGS) approach and their treatment outcome was assessed. In the present study, 41.2% of patients as KIT/PDGFRA/BRAF WT GIST examined with RT‑qPCR and Sanger sequencing were confirmed to be carriers of pathogenic KIT/PDGFRA mutations by NGS and were responsive to TKI. The percentage of genuinely KIT/PDGFRA WT GIST in the present study thereby dropped from the initial 14.3% detected with the RT‑qPCR and Sanger sequencing to 7.6% after NGS. Their outcome was universally poor. The reliability of RT‑qPCR and direct Sanger sequencing results in this setting is therefore insufficient and it is recommended that NGS becomes a requirement for treatment decision at least in KIT/PDGFRA/BRAF WT GIST as determined by RT‑qPCR and Sanger sequencing.

A Gastroenterologist's Approach to the Diagnosis and Management of Gastrointestinal Stromal Tumors

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal (GI) tract. These tumors have been shown to harbor oncogenic mutations of the c-kit tyrosine kinase receptor or platelet-derived growth factor receptor alpha (PDGFRA). Immunohistochemical analysis of GISTs allows for the differentiation of these tumors from other mesenchymal tumors of the GI tract such as leiomyomas and leiomyosarcomas. All GISTs have the potential to behave in a malignant fashion. Tumor location, size, and mitotic index are factors used to predict the risk of malignant behavior. Endoscopy and endoscopic ultrasound play a critical role in the diagnosis of GISTs and can yield important information to further risk-stratify tumors and determine management. This article provides a gastroenterologist's perspective on the diagnosis and management of GISTs.

Comparison of prognosis between neoadjuvant imatinib and upfront surgery for GIST: A systematic review and meta-analysis

Background: Significant survival benefit of adjuvant imatinib therapy has been observed in gastrointestinal stromal tumor (GIST). However, the impact of neoadjuvant imatinib on prognosis of GIST remains unclear. This meta-analysis aimed to compare the prognostic impact between upfront surgery and neoadjuvant imatinib plus surgery on GIST.

Methods: A comprehensive literature search was performed to identify eligible studies up to 30 Sep 2021, through PubMed, Embase, Web of Science, and Cochrane Library. Studies compared the impact of upfront surgery and neoadjuvant imatinib plus surgery on disease-free (DFS) or overall survival (OS) in patients with GIST were selected.

Results: Seven eligible studies with 17,171 patients were included. The reduction rates of tumor size in rectal and mixed site GIST were 33% and 29.8%, respectively. Neoadjuvant imatinib was not significantly associated with DFS compared with no-neoadjuvant therapy in rectal GIST (HR: 0.71, 95% CI: 0.35–1.41). The OS of rectal GIST was significantly improved by neoadjuvant imatinib compared with no-neoadjuvant therapy (HR: 0.36, 95% CI: 0.17–0.75).

Conclusion: Neoadjuvant imatinib therapy contributed to tumor shrinkage and R0 resection of rectal GIST. Neoadjuvant imatinib plus surgery significantly improved overall survival of rectal GIST in comparison with upfront surgery.

Efficacy of SCF drug conjugate targeting c-KIT in gastrointestinal stromal tumor

BACKGROUND

Gastrointestinal stromal tumor (GIST) is a rare type of cancer that occurs in the gastrointestinal tract. The majority of GIST cases carry oncogenic forms of KIT, the receptor for stem cell factor (SCF). Small molecule kinase inhibitor imatinib is effective in prolonging the survival of GIST patients by targeting KIT. However, drug resistance often develops during the therapeutic treatment. Here, we produced a SCF-emtansine drug conjugate (SCF-DM1) with favorable drug efficacy towards GIST cells.

METHODS

Recombinant human SCF (rhSCF) was expressed in E. coli cells and further purified with Ni-NTA Sepharose and Phenyl Sepharose. It was then conjugated with DM1, and the conjugated product SCF-DM1 was evaluated using in vitro cell-based assays and in vivo xenograft mouse model.

RESULTS

SCF-DM1 was effective in inhibiting imatinib-sensitive and -resistant GIST cell lines and primary tumor cells, with IC₅₀ values of < 30 nM. It induced apoptosis and cell cycle arrest in GIST cells. In xenograft mouse model, SCF-DM1 showed favorable efficacy and safety profiles.

CONCLUSIONS

rhSCF is a convenient and effective vector for drug delivery to KIT positive GIST cells. SCF-DM1 is an effective drug candidate to treat imatinib-sensitive and -resistant GIST.

Systemic Therapy for Gastrointestinal Stromal Tumor: Current Standards and Emerging Challenges

Gastrointestinal stromal tumor (GIST), though rare, is the most common mesenchymal tumors of the gastrointestinal tract. KIT or PDGFRα mutation plays as an oncogenic driver in the majority of GISTs. Surgical resection is the only curative treatment for localized disease. The discovery of imatinib with promising anti-tumor effect and successive tyrosine kinase inhibitors (TKI), including second-line sunitinib and third-line regorafenib, revolutionized the management of advanced and metastatic GIST over the past two decades. Recently, ripretinib and avapritinib were approved for the fourth line setting and for PDGFRA exon 18-mutant GIST in first-line setting, respectively. Despite multi-line TKIs exerted ability of disease control, drug resistance remained an obstacle for preventing rapid disease progression. Experimental TKIs or novel therapeutic targets may further improve treatment efficacy. Immune checkpoint inhibitors such as anti-programmed cell death protein-1 (PD1) and anti-CTL-associated antigen 4 (CTLA-4) showed moderate response in early phase trials composed of heavily pretreated patients. KIT/PDGFRα wild-type GISTs are generally less sensitive to imatinib and late-line TKIs. Recent studies demonstrated that targeting fibroblast growth factor receptor signaling may be a potential target for the wild-type GISTs.

Complete response of advanced rectal gastrointestinal stromal tumors after imatinib treatment: A case report and literature review

RATIONALE

Patients with rectal gastrointestinal stromal tumors (GISTs) who achieve a complete response (CR) with imatinib therapy have rarely been reported in the literature. Moreover, no treatment guidelines have been established for rectal GIST patients with CR after imatinib treatment, warranting further studies.

PATIENT CONCERNS

A 51-year-old man presented to our outpatient clinic in October 2013 with complaints of difficulty to defecate and a change in stool characteristics. During digital rectal examination, a mass was palpated within 5 cm from the anal verge. Contrast-enhanced computed tomography revealed a 8.1 × 7.2-cm rectal mass with significant enhancement during the arterial phase.

DIAGNOSES

A diagnosis of GIST was established after conducting needle biopsy and immunohistochemistry staining.

INTERVENTIONS

Imatinib therapy (400 mg/d, oral administration) was immediately started. When the patient achieved clinical CR (cCR), the oncologist recommended the patient to continue imatinib treatment.

OUTCOMES

At 7 months after imatinib administration, the patient achieved cCR. As suggested by the oncologist, the patient continued to receive imatinib treatment after cCR. After 13 months, the patient spontaneously stopped imatinib. Finally, tumor recurrence was observed 7 months later.

LESSONS

Surgery remains the mainstay of treatment for advanced rectal GIST patients who achieve cCR after imatinib treatment. Close follow-up and continuous imatinib treatment are indicated in patients who cannot undergo surgery.

Clinical outcomes of endoscopic treatment for gastric gastrointestinal stromal tumors: a single-center study of 240 cases in China

BACKGROUND AND AIMS

Endoscopic resection (ER) gradually becomes an important treatment method for gastrointestinal stromal tumors (GISTs). The aim of this study is to evaluate the efficacy and safety of ER of gastric GISTs.

METHODS

This retrospective study included 240 patients with gastric GISTs who underwent ER at Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology from January 2010 to December 2019. The clinicopathologic, endoscopic and follow-up data of the patients were collected and analyzed.

RESULTS

The mean maximum tumor diameter was 1.67 ± 1.00 cm (range 0.2-6.5 cm), of which 156 cases (65.00%) were small gastric GISTs (tumor diameter < 2 cm). A total of 43 patients (17.92%) had perioperative bleeding, including 40 cases (16.67%) of minor bleeding and three cases (1.25%) of major bleeding. Perioperative perforation occurred in 101 patients (42.08%), of which 51 patients (21.25%) were active perforation and 50 patients (20.83%) were passive perforation. The en bloc resection rate was 97.08% (233/240), and seven cases (2.92%) had piecemeal resection. There were three cases (1.92%) of small gastric GISTs at intermediate risk and one case (0.64%) at high risk. A total of 193 patients were followed up, and no tumor residual, recurrence or metastasis occurred within a median follow-up time of 30 months (range 1-127 months).

CONCLUSIONS

Endoscopic treatment for gastric GISTs is safe and effective. Piecemeal resection does not seem to be related to the patient's prognosis. Endoscopic resection can be performed if patients are willing to remove small gastric GISTs.

Gastrointestinal Stromal Tumors and the General Surgeon

Gastrointestinal stromal tumors (GISTs) are rare malignancies of the gastrointestinal tract but are the most common sarcoma. This review covers aspects of the care of patients with GIST relevant to surgeons. In particular, management of sub-2 cm GISTs, the utility of neoadjuvant and adjuvant therapy for primary GISTs, and indications for surgery in the setting of metastatic disease are discussed.

p53 as a biomarker and potential target in gastrointestinal stromal tumors

KIT and PDGFRA play a major role in the oncogenic process in gastrointestinal stroma tumors (GIST) and small molecules have been employed with great success to target the KIT and PDGFRA pathways in this cancer. However, approximately 10% of patients with GIST are resistant to current targeted drug therapy. There is a need to explore other potential targets. Although p53 alterations frequently occur in most cancers, studies regarding p53 in GIST have been limited. The CDKN2A/MDM2/p53 axis regulates cell cycle progression and DNA damage responses, which in turn control tumor growth. This axis is the major event required for transformation from low- to high-risk GIST. Generally, p53 mutation is infrequent in GIST, but p53 overexpression has been reported to be associated with high-risk GIST and unfavorable prognosis, implying that p53 should play a critical role in GIST. Also, Wee1 regulates the cell cycle and the antitumor activity of Wee1 inhibition was reported to be p53 mutant dependent. In addition, Wee1 was reported to have potential activity in GIST through the regulation of KIT protein and this mechanism may be dependent on p53 status. In this article, we review previous reports regarding the role of p53 in GIST and propose targeting the p53 pathway as a novel additional treatment strategy for GIST.

Ripretinib in advanced gastrointestinal stromal tumors: an overview of current evidence and drug approval

Over the past 20 years, the management of gastrointestinal stromal tumors has acted as an important model in the advancement of molecularly targeted therapies for solid tumors. The success of imatinib has established it as a lasting therapy in the management of early-stage and advanced disease in the first-line setting. Imatinib resistance inevitably develops, resulting in the need for further lines of therapy. Ripretinib is an orally administered switch-control tyrosine kinase inhibitor, specifically developed to target both primary and secondary KIT and PDGFRα resistance mutations. Herein, the authors discuss the molecular rationale, the preclinical evidence and the clinical use of ripretinib in the treatment of gastrointestinal stromal tumors in the advanced stages of disease.

Mutational Analysis of c-KIT and PDGFRA in Canine Gastrointestinal Stromal Tumors (GISTs)

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the canine gastrointestinal tract and are diagnosed by the immunohistochemical expression of the receptor tyrosine kinase (RTK) KIT. Activating mutations of the proto-oncogenes c-KIT and PDGFRA drive GIST oncogenesis and are used to predict the response to RTK-inhibitors in human oncology. Currently, the frequency and significance of these mutations in canine GIST have not been adequately explored. Therefore, we investigated the mutational status of c-KIT (exons 9, 11 and 13) and PDGFRA (exons 12 and 18) genes by PCR followed by fragment analysis for c-KIT deletions and PCR followed by screening with DHPLC and direct sequencing confirmation for single nucleotide variations in 17 formalin-fixed paraffin-embedded canine GISTs confirmed by KIT immunopositivity. c-KIT mutations were detected in 47% of cases, with a mutation detection rate significantly higher (p = 0.0004, Fisher’s exact test) and always involving exon 11. A PDGFRA gene mutation (exon 18) was identified in one case. Even if follow-up data were not available for all cases, four cases with documented abdominal metastases displayed c-KIT mutations. These data confirm that c-KIT exon 11 mutations occur frequently in canine GISTs, and identify the presence of a PDGFRA mutation similar to human GISTs. This study also suggests a potential association of c-KIT mutation with more aggressive biological behavior.

Risk Factors and Prognostic Analysis of Gastrointestinal Stromal Tumor Recurrence-Metastasis

Objective

Gastrointestinal stromal tumors (GISTs) are potential malignancies that occur in the digestive tract. This study aimed to investigate the risk factors and prognosis of recurrence and metastasis of gastrointestinal stromal tumor (GIST).

Methods

From January 2018 to December 2019, 422 patients with GIST who received surgery in the First Affiliated Hospital of Wenzhou Medical University were enrolled. Their clinical data were retrospectively analyzed, and their follow-ups were continued until March 31, 2022. Subsequently, univariate and multivariate Cox analyses, survival curves, and nomograms were adopted to explore the relationship between clinicopathological characteristics and recurrence or metastasis in patients with GIST.

Results

Univariate and multivariate Cox analysis exhibited that the prognosis of patients was affected by tumor rupture (P = 0.040), tumor location (P < 0.001), tumor diameter (P = 0.016), mitotic figures (P < 0.001), and risk grade (P < 0.009). The above variables were selected to create the nomogram for 3-year disease-free survival (DFS). The 3-year the ROC (receiver operating characteristic) curves of the nomogram were (0.878 95% confidence interval [CI]: 0.871-0.939).

Conclusion

Collectively, risk factors affecting postoperative recurrence or metastasis of GIST consist of primary site of tumors, tumor rupture, tumor diameter >10 cm, high-risk tumor classification, and mitotic figures ≥10 per 50 HPFs. And the application of nomogram may help physicians provide individualized diagnosis and treatment for patients with GISTs following surgical resection.

Synchronous occurrence of gastrointestinal stromal tumor, pancreatic intraductal papillary mucinous neoplasm, and intrahepatic cholangiocarcinoma: Case report

RATIONALE

Gastrointestinal stromal tumor (GIST) is the most common primary mesenchymal tumors in gastrointestinal tract. Synchronous occurrence of GIST and tumors in other organs is rare. We first report an exceedingly rare case of synchronous occurrence of gastric GIST, pancreatic intraductal papillary mucinous neoplasm (IPMN) and intrahepatic cholangiocarcinoma.

PATIENT CONCERNS

A 70-year-old male presented to our hospital because of abdominal pain and dyspepsia. Tumor markers and liver function were abnormal. Abdomen computed tomography showed concurrent tumors in stomach, pancreas, and liver.

DIAGNOSIS

Pathology confirmed synchronous occurrence of gastric GIST, pancreatic IPMN and intrahepatic cholangiocarcinoma.

INTERVENTIONS

Mass excision, partly gastrectomy, wedge resection of VIII liver segments, and pancreatic-oduodenectomy were performed.

OUTCOMES

During the 18-month follow-up, both laboratory tests and computed tomography examination revealed no sign of recurrence or metastasis. Currently, the patient is free of clinical symptoms such as abdominal discomfort, jaundice, and fever.

CONCLUSION

As yet, no cases simultaneously with gastric GIST, pancreatic IPMN and intrahepatic cholangiocarcinoma have been described in literatures. This report increases the knowledge to avoid misdiagnosis and delayed therapy for coexistence of the described 3 types of neoplasm.

The synergistic therapeutic effect of imatinib and protein kinase CK2 Inhibition correlates with PI3K-AKT activation in gastrointestinal stromal tumors

BACKGROUND

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. Casein kinase 2 (CK2) has been reported to be involved in several cellular processes in multiple cancers. However, the role of CK2 in GIST remains unclear.

AIM

We aimed to investigate the combinatorial treatment of imatinib (IM) and CK2 inhibition on the progression of GISTs.

METHODS

GIST biopsies and adjacent normal tissues were collected from patients. GIST882 and GIST48 cell lines were subjected to investigate the effect of IM and CK2 inhibition in GIST cells. CCK-8 assay, Caspase-3 activity assay, western blotting, and flow cytometry analysis were employed in the present investigation.

RESULTS

Our results showed that CK2 was highly expressed in GIST biopsies, and inhibition of CK2 resulted in decrease in cell viability and increase in apoptosis of GIST cells. Moreover, the combination treatment with CX-4945 (CX) and IM resulted in a more significant decrease in cell viability and increase in cell apoptosis compared with mono-treatment. Mechanistically, the combination treatment influenced the activation of the PI3K/AKT pathway. The activation of the PI3K/AKT pathway reversed the synergistic impacts of the combined treatment on cell viability and apoptosis.

CONCLUSION

Our results demonstrated that inhibition of CK2 combined with IM exhibited a synergistic anti-cancer effect on GIST cells through inactivation of the PI3K/AKT pathway.

Hematologic toxicities of sunitinib in patients with gastrointestinal stromal tumors: a systematic review and meta-analysis

PURPOSE

Sunitinib offers a significant survival benefit to patients with imatinib-resistant gastrointestinal stromal tumors (GIST). However, the incidence and risk of sunitinib-induced hematologic toxicities in such a population are often overlooked and have not been well characterized. This meta-analysis was performed to assess the summary incidence and risk of hematologic toxicities secondary to sunitinib in patients with GIST.

METHODS

Searches were performed in PubMed, Embase, Cochrane Library, and Web of Science as well as ClinicalTrials.gov to identify relevant studies up to April 2022. Studies with adequate safety profile, including anemia, neutropenia, and thrombocytopenia, were included to calculate the pooled incidence, relative risk (RR), and corresponding 95% confidence intervals (CIs). This study was registered with PROSPERO under number CRD42022328202.

RESULTS

A total of 2593 patients from 13 studies were included in the present meta-analysis. For patients with GIST assigned to sunitinib, the overall incidences of all-grade anemia, neutropenia, and thrombocytopenia were 26.2% (95% CI, 14.9-39.4%), 41.8% (95% CI, 29.0-55.1%), and 36.4% (95% CI, 22.8-51.1%), respectively. Regarding high-grade (grades 3 and 4) events, there were 4.7% (95% CI, 3.8-5.6%) for anemia, 9.3% (95% CI, 5.6-13.7%) for neutropenia and 5.0% (95% CI, 2.9-7.3%) for thrombocytopenia. Compared to placebo arms, sunitinib was related to an increased risk of high-grade neutropenia with an RR of 10.39 (95% CI, 1.53-70.72; p = 0.017).

CONCLUSIONS

Sunitinib carries a relatively high incidence of hematologic toxicities and a substantial increased risk of high-grade neutropenia in patients with GIST. Appropriate prevention and management seem to be inevitable.

Next questions for the medical treatment of gastrointestinal stromal tumor

PURPOSE OF REVIEW

Since its approval in 2002, imatinib remains the standard first-line treatment for patients with advanced gastrointestinal stromal tumors (GISTs). Overall, all the drugs approved for patients who have developed secondary resistance to imatinib are less effective than imatinib in first-line. Even if, overall survival of patients with advanced GIST has improved over time the last 20 years, imatinib-resistant GIST remains therefore a difficult-to-treat cancer. The aim of this review is to elaborate on the potential strategies to improve outcome for patients with imatinib-refractory disease.

RECENT FINDINGS

New-generation potent KIT and PDGFRA inhibitors such as ripretinib and avapritinib developed for the treatment of GIST have shown very promising clinical activity in patients with highly refractory disease. However, both failed to improve outcome in comparison with standard of care in earlier lines settings. Clinical trials investigating the efficacy of multikinase inhibitor with highly specific KIT inhibitors are currently ongoing. Targeting the microenvironment of GIST may also represent a promising approach and is investigated in several clinical studies.

SUMMARY

Imatinib-refractory GIST still represent a therapeutic challenge. It is likely that only combination therapies with new generation of tyrosine kinase inhibitors (TKIs) and/or immune-oncology agents might potentially result in an enhanced therapeutic efficacy compared with current standard of care.

Metastasectomy in Leiomyosarcoma: A Systematic Review and Pooled Survival Analysis

Simple Summary

Leiomyosarcoma (LMS) is an aggressive soft tissue sarcoma with a poor prognosis. Approximately 40% of patients will develop metastatic disease. The optimal treatment for patients with metastatic LMS is not well established, and there are no randomized controlled trials regarding metastasectomy. This systematic review and pooled survival analysis aims to assess the survival in patients undergoing a metastasectomy for LMS and compare the outcomes based on the site of metastasectomy. We identified that patients with LMS metastases in the lungs, liver, spine, and brain can undergo metastasectomy with acceptable survival. Two studies have compared survival outcomes between patients treated and not treated with metastasectomy; despite their low quality, these studies support a survival benefit associated with metastasectomy.

Abstract

This study assesses the survival in patients undergoing metastasectomy for leiomyosarcoma (LMS) and compares the outcomes by the site of metastasectomy. We conducted a systematic review and pooled survival analysis of patients undergoing metastasectomy for LMS. Survival was compared between sites of metastasectomy. We identified 23 studies including 573 patients undergoing metastasectomy for LMS. The pooled median survival was 59.6 months (95% CI 33.3 to 66.0). The pooled median survival was longest for lung metastasectomy (72.8 months 95% CI 63.0 to 82.5), followed by liver (34.8 months 95% CI 22.3 to 47.2), spine (14.1 months 95% CI 8.6 to 19.7), and brain (14 months 95% CI 6.7 to 21.3). Two studies compared the survival outcomes between patients who did, versus who did not undergo metastasectomy; both demonstrated a significantly improved survival with metastasectomy. We conclude that surgery is currently being utilized for LMS metastases to the lung, liver, spine, and brain with acceptable survival. Although low quality, comparative studies support a survival benefit with metastasectomy. In the absence of randomized studies, it is impossible to determine whether the survival benefit associated with metastasectomy is due to careful patient selection rather than a surgical advantage; limited data were included about patient selection.

Clinicopathological features of Gastrointestinal Stromal Tumors and review of the literature

Objective: Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasias of the gastrointestinal system (GIS). The malignancy potential of GISTs may vary ranging from indolent tumors to progressive malignant tumors. This study aims to define clinicopathological and immunohistochemical features of GISTs diagnosed in our institute with a review of the literature. Method: A total of 28 GIST cases were included in the study. The Hematoxylin&Eosin stained slides of surgical resection materials and cell blocks and immunohistochemistry performed slides were reviewed by a pathologist. The immunohistochemical expression with CD117, DOG-1, CD34, SMA, and S100 was scored between 0 and 3 points according to staining intensity. Descriptive statistics were used in the study. The demographic data, prognostic histopathological, and immunohistochemical findings are evaluated with the literature indications. Result: Eleven of the cases were male and seventeen were female. The age range was 18-88. The most common site of GISTs was the stomach, followed by the small intestine, colorectal region, and, esophagus. Twenty of the tumors were resected surgically, four were endoscopic biopsy material and four were fine-needle aspiration biopsies. The tumor size in measurable materials ranged from 0,2 to 22 cm. The mitotic count in 50 HPF ranges from 0 to 10. Seven of the GISTs were high grade and the remaining 21 were low grade. The majority of the cases were composed of spindle cells, 3 were epithelioid and 3 were the mixed type with spindle and epitheloid cells. Conclusion: A variety of criteria has been proposed to estimate the malignancy potential of GISTs and predict prognosis but definite prognostic criteria remain uncertain. Further studies with larger series of GISTs consisting of different types of biopsy materials may help define criteria to predict prognosis precisely.

Clinicopathologic Characteristics and Prognosis of PDGFRA-Mutant Gastrointestinal Stromal Tumors: A Large-Scale, Multi-Institutional, Observational Study in China

INTRODUCTION

To evaluate clinicopathologic features and prognosis of post-complete resection in patients with PDGFRA-mutant gastrointestinal stromal tumor (GIST), and even to establish a relapse-free survival (RFS) prognostic model for this subgroup.

METHODS

This retrospective study used data from patients with primary PDGFRA-mutant GIST who underwent complete resection (2005-2019) at 16 large-scale medical centers in China. Stepwise multivariate Cox regression models were performed to build the prediction model, in which the potential predictors were available in routine clinical practice and using the risk score functions. The prediction model was cross-validated by calibration histogram and time-dependent receiver operating characteristic curves.

RESULTS

A total of 280 patients with PDGFRA-mutant (172 D842V-mutant and 108 non-D842V-mutant) GIST after complete resection were enrolled. Most tumors originated in the stomach (89.6%). The 1-, 3-, and 5-year RFS rates were 95.9%, 91.2%, and 89.5%, respectively. The RFS of the non-D842V-mutant group was superior to that of the D842V group (P = 0.033). Multivariate analysis demonstrated that D842V mutation (P = 0.017), non-gastric tumor (P < 0.001), and Ki-67 > 5% (P = 0.005) were the independent variables influencing the prognosis of patients with PDGFRA-mutant GIST. The scoring model showed the predicted and actual cumulative 1-, 3- and 5-year follow-up relapse rates fit well.

CONCLUSIONS

PDGFRA-mutant GIST mostly originated in the stomach and had a favorable prognosis after surgery. Non-D842V-mutant patients might have better prognoses than D842V-mutant patients. The prognostic model demonstrated favorable prediction accuracy, suggesting its clinical utility.

Familial gastrointestinal stromal tumors with KIT germline mutation in a Chinese family: A case report

BACKGROUND

Familial gastrointestinal stromal tumors (GISTs) is a rare autosomal dominant disorder characterized by an array of clinical manifestations. Only 35 kindreds with germline KIT mutations and six with germline PDGFRA mutations have been reported so far. It is often characterized by a series of manifestations, such as multiple lesions and hyperpigmentation. However, the effect of imatinib treatment in these patients is still uncertain.

CASE SUMMARY

Here, we report two patients (father and daughter) in a Chinese family (for the first time) with germline KIT mutation, and described their pathology, genetics and clinical manifestations. A 25-year-old Chinese woman went to hospital because of abdominal pain, and computed tomography showed multiple tumors in the small intestine. Small pigmented spots appeared on the skin within a few months after birth. Her father also had multiple pigmented spots and a history of multifocal GISTs. Multiple GISTs associated with diffuse interstitial Cajal cells (ICCs) hyperplasia were positive for CD117 and DOG-1. Gene sequencing revealed a germline mutation at codon 560 of exon 11 (p.V560G) of KIT gene in these two patients. Imatinib therapy showed the long-lasting disease stability after resection. Remarkably, the hypopigmentation of the skin could also be observed. Luckily germline KIT mutation has not been identified yet in the 3-year-old daughter of the female patient.

CONCLUSION

Diagnosis of familial GISTs depends on combination of diffuse ICCs hyperplasia, germline KIT/PDGFRA mutation, hyperpigmentation and family history.

The Molecular Biology of Soft Tissue Sarcomas: Current Knowledge and Future Perspectives

Soft tissue sarcomas are malignant tumors of mesenchymal origin, encompassing a large spectrum of entities that were historically classified according to their histological characteristics. Over the last decades, molecular biology has allowed a better characterization of these tumors, leading to the incorporation of multiple molecular features in the latest classification of sarcomas as well as to molecularly-guided therapeutic strategies. This review discusses the main uses of molecular biology in current practice for the diagnosis and treatment of soft tissue sarcomas, in addition to perspectives for this rapidly evolving field of research.

Targeting the translational machinery in gastrointestinal stromal tumors (GIST): a new therapeutic vulnerability

Although KIT-mutant GISTs can be effectively treated with tyrosine kinase inhibitors (TKIs), many patients develop resistance to imatinib mesylate (IM) as well as the FDA-approved later-line agents sunitinib, regorafenib and ripretinib. Resistance mechanisms mainly involve secondary mutations in the KIT receptor tyrosine kinase gene indicating continued dependency on the KIT signaling pathway. The fact that the type of secondary mutation confers either sensitivity or resistance towards TKIs and the notion that secondary mutations exhibit intra- and intertumoral heterogeneity complicates the optimal choice of treatment in the imatinib-resistant setting. Therefore, new strategies that target KIT independently of its underlying mutations are urgently needed. Homoharringtonine (HHT) is a first-in-class inhibitor of protein biosynthesis and is FDA-approved for the treatment of chronic myeloid leukemia (CML) that is resistant to at least two TKIs. HHT has also shown activity in KIT-mutant mastocytosis models, which are intrinsically resistant to imatinib and most other TKIs. We hypothesized that HHT could be effective in GIST through downregulation of KIT expression and subsequent decrease of KIT activation and downstream signaling. Testing several GIST cell line models, HHT led to a significant reduction in nascent protein synthesis and was highly effective in the nanomolar range in IM-sensitive and IM-resistant GIST cell lines. HHT treatment resulted in a rapid and complete abolishment of KIT expression and activation, while KIT mRNA levels were minimally affected. The response to HHT involved induction of apoptosis as well as cell cycle arrest. The antitumor activity of HHT was confirmed in a GIST xenograft model. Taken together, inhibition of protein biosynthesis is a promising strategy to overcome TKI resistance in GIST.

The GIST of Advances in Treatment of Advanced Gastrointestinal Stromal Tumor

Gastrointestinal stromal tumor (GIST) is the most common malignant neoplasm of mesenchymal origin and a compelling clinical and biologic model for the rational development of molecularly targeted agents. This is because the majority of GISTs are driven by gain-of-function mutations in KIT or PDGFRA receptor tyrosine kinases. Specific GIST mutations circumscribe well-defined molecular subgroups that must be determined during the diagnostic work-up to guide clinical management, including therapeutic decisions. Surgery is the cornerstone treatment in localized disease and can also be clinically relevant in the metastatic setting. The correct combination and sequence of targeted agents and surgical procedures improves outcomes for patients with GIST and should be discussed individually within multidisciplinary expert teams. All currently approved agents for the treatment of GIST are based on orally available tyrosine kinase inhibitors targeting KIT and PDGFRA oncogenic activation. Although first-line imatinib achieves remarkable prolonged disease control, the benefit of subsequent lines of treatment is more modest. Novel therapeutic strategies focus on overcoming the heterogeneity of KIT or PDGFRA secondary mutations and providing more potent inhibition of specific challenging mutations. This article reviews the current understanding and treatment of GIST, with an emphasis on recent advances.

New treatment strategies for advanced-stage gastrointestinal stromal tumours

When gastrointestinal stromal tumour (GIST), the most common form of sarcoma, was first recognized as a distinct pathological entity in the 1990s, patients with advanced-stage disease had a very poor prognosis owing to a lack of effective medical therapies. The discovery of KIT mutations as the first and most prevalent drivers of GIST and the subsequent development of the first KIT tyrosine kinase inhibitor (TKI), imatinib, revolutionized the treatment of patients with this disease. We can now identify the driver mutation in 99% of patients with GIST via molecular diagnostic testing, and therapies have been developed to treat many, but not all, molecular subtypes of the disease. At present, seven drugs are approved by the FDA for the treatment of advanced-stage GIST (imatinib, sunitinib, regorafenib, ripretinib, avapritinib, larotrectinib and entrectinib), all of which are TKIs. Although these agents can be very effective for treating certain GIST subtypes, challenges remain and new therapeutic approaches are needed. In this Review, we discuss the molecular subtypes of GIST and the evolution of current treatments, as well as their therapeutic limitations. We also highlight emerging therapeutic approaches that might overcome clinical challenges through novel strategies predicated on the biological features of the distinct GIST molecular subtypes.

Challenges in the management of metastatic gastrointestinal stromal tumor in a patient with neurofibromatosis type 1: a case report

BACKGROUND

Neurofibromatosis type 1 is an inherited cancer predisposition syndrome that is caused by a mutation in the NF1 gene that encodes neurofibromin. Patients with neurofibromatosis type 1 have a higher risk of gastrointestinal stromal tumor. This study reports the case of a patient with gastrointestinal stromal tumor who was later diagnosed to have neurofibromatosis type 1 and, unlike usual features, had some uncommon features such as occurrence at an early age and unusual site of origin.

CASE

We report the case of a 29-year-old Indian female diagnosed to have gastrointestinal stromal tumor originating from the greater curvature of the stomach. Gastrointestinal stromal tumor was wild type, negative for c-kit and platelet-derived growth factor receptor, and had an aggressive clinical course not responding to oral tyrosine kinase inhibitors. On later evaluation, we found that the patient had germline mutation in NF1. This case has some unusual features compared with gastrointestinal stromal tumor cases reported in neurofibromatosis type 1. Firstly, the age of onset for gastrointestinal stromal tumor in neurofibromatosis type 1 is earlier in our case compared with previous cases reported in literature. Secondly, the site of occurrence is in the stomach, without involving other parts of the intestine. Gastrointestinal stromal tumor in neurofibromatosis type 1 is usually multifocal, and small intestine is the common site of occurrence. When occurring in the stomach, it is usually associated with other lesions in the small intestine. Lastly, the clinical course is aggressive compared with previous case reports and series.

CONCLUSION

Our patient had germline NF1 mutation and cutaneous stigmata of neurofibromatosis. Our patient had unicentric gastrointestinal stromal tumor occurring at younger age and involving greater curvature of the stomach, with spindle cell type histology and high-risk features. If gastrointestinal stromal tumor occurs at young age, we should look into neurocutaneous markers.

Gastrointestinal Stromal Tumor

Over the past 20 years, gastrointestinal stromal tumor (GIST) has evolved into an increasingly complex clinical entity with ever more challenges. While surgical resection is the gold standard, advancements in genetic testing, therapeutic options, immunotherapy, and management of metastatic disease necessitate a comprehensive, multimodal approach for these tumors. This chapter highlights the importance of genomic testing of GIST, the use of neoadjuvant and adjuvant therapy for localized disease, surgical principles for GIST, as well as current and new approaches for addressing metastatic disease.

The landscape of genetic aberrations in myxofibrosarcoma

Myxofibrosarcoma (MFS) is a rare subtype of sarcoma, whose genetic basis is poorly understood. We analyzed 69 MFS cases using whole-genome (WGS), whole-exome (WES), and/or targeted-sequencing (TS). Newly sequenced genomic data were combined with additional deposited 116 MFS samples. WGS identified a high number of structural variations (SVs) per tumor most frequently affecting the TP53 and RB1 loci, 40% of tumors showed a BRCAness-associated mutation signature, and evidence of chromothripsis was found in all cases. Most frequently mutated /copy number altered genes affected known disease drivers such as TP53 (56.2%), CDKN2A/B (29.7%), RB1 (27.0%), ATRX (19.5%), and HDLBP (18.9%). Several previously unappreciated genetic aberrations including MUC17, FLG, and ZNF780A were identified in more than 20% of patients. Longitudinal analysis of paired diagnosis and relapse time points revealed a 1.2-fold mutation number increase accompanied with substantial changes in clonal composition over time. This study highlights the genetic complexity underlying sarcomagenesis of MFS. This article is protected by copyright. All rights reserved.

The role of neoadjuvant imatinib in gastrointestinal stromal tumor (GIST) patients - 20 years of experience from a tertial referral center

Surgery is the cornerstone of gastrointestinal stromal tumor (GIST) treatment, and adjuvant therapy with imatinib has improved survival for high‐risk tumors. The use of imatinib preoperatively has been increasing, but efficacy and impact on patient outcomes have not been formally investigated. This is a retrospective study from a single‐center cohort of patients diagnosed with GIST and treated with neoadjuvant imatinib at Karolinska University Hospital in Stockholm, Sweden over a 20‐year period. Eighty‐four patients diagnosed with GIST and treated with neoadjuvant imatinib were identified and included. Tumors were located throughout the whole gastrointestinal tract but most frequently in the stomach (n = 29; 35%) and the small intestine (n = 30; 36%), followed by the rectum (n = 12; 14%) and the gastroesophageal junction (n = 10; 12%). The tumors were large (mean 10.5 cm) and decreased after treatment (mean 7.6 cm). Main indications for neoadjuvant imatinib were tumor size or anatomical location. None of the patients with stomach tumors and four patients with tumors near the gastroesophageal junction underwent gastrectomy. Three patients with tumors in the small intestine underwent pancreaticoduodenectomy, whereas seven patients with rectal tumors underwent rectal amputation. After surgery, 94% (n = 79) of the tumors had R0‐resection. About one‐fourth experienced local relapse or distant metastasis. In conclusion, neoadjuvant imatinib can reduce tumor size and prevent high morbidity due to more extensive surgery, or at least reduce the extent of the surgery, especially for tumors in the stomach or small intestine.

Cost-Effectiveness Analysis of Tyrosine Kinase Inhibitors in Gastrointestinal Stromal Tumor: A Systematic Review

Background: The introduction of tyrosine kinase inhibitor (TKI) therapy has dramatically improved the clinical effectiveness of patients with locally advanced and/or metastatic gastrointestinal stromal tumors (GIST), and this systematic review was conducted aiming at the cost-effectiveness analysis of TKIs in GIST.

Methods: A thorough literature search of online databases was performed, using appropriate terms such as “gastrointestinal stromal tumor or GIST,” “cost-effectiveness,” and “economic evaluation.” Data extraction was conducted independently by two authors, and completeness of reporting and quality of the evaluation were assessed. The systematic review was conducted following the PRISMA statement.

Results: Published between 2005 and 2020, 15 articles were incorporated into the systematic review. For advanced GIST, imatinib followed by sunitinib was considered cost-effective, and regorafenib was cost-effective compared with imatinib re-challenge therapy in the third-line treatment. For resectable GIST, 3-year adjuvant imatinib therapy represented a cost-effective treatment option. The precision medicine-assisted imatinib treatment was cost-effective compared with empirical treatment.

Conclusion: Although identified studies varied in predicted costs and quality-adjusted life years, there was general agreement in study conclusions. More cost-effectiveness analysis should be conducted regarding more TKIs that have been approved for the treatment of GIST.

Systematic Review Registration:https://www.crd.york.ac.uk/, PROSPERO: CRD42021225253.

Efficacy and Safety of Endoscopic Resection for Small Gastric Gastrointestinal Stromal Tumors in Elderly Patients

Background

Gastrointestinal stromal tumors (GISTs) are prevalent in elderly patients. Endoscopic resection has become popular for treating small (≤5 cm) gastric GISTs. However, little is known about the outcomes of endoscopic resection in elderly patients.

Aim

To assess the efficacy and safety of endoscopic resection for small (≤5 cm) gastric GISTs in elderly patients (≥65 years old).

Methods

A total of 260 patients (265 lesions) with gastric GISTs treated via endoscopic resection from January 2011 to May 2020 were retrospectively analyzed. Among them, 65 patients were ≥65 years old (elderly group), and 195 patients were <65 years old (nonelderly group). Clinicopathological characteristics, postoperative complications, and tumor recurrence rates between the two age groups were compared.

Results

A total of 260 patients with primary small (≤5 cm) gastric GISTs were treated with endoscopic resection. The median ages of the elderly and nonelderly groups were 68 (range 65-83) years and 55 (range 32-64) years, respectively. Elderly patients showed a higher incidence of comorbidities compared with nonelderly patients (61.5% versus 32.3%s, respectively; p < 0.001). All elderly patients and 99.0% of nonelderly patients underwent en bloc resection; only two nonelderly patients received piecemeal resection. No significant differences were found regarding postoperative complications or tumor recurrence rates between the two groups.

Conclusions

Although elderly patients had more comorbidities than nonelderly patients, both groups had similar postoperative complications and recurrence rates. We suggest that endoscopic resection performed by experienced endoscopists is safe and effective for treating small (≤5 cm) gastric GISTs in elderly patients.

Mutated KIT Tyrosine Kinase as a Novel Molecular Target in Acute Myeloid Leukemia

KIT is a type-III receptor tyrosine kinase that contributes to cell signaling in various cells. Since KIT is activated by overexpression or mutation and plays an important role in the development of some cancers, such as gastrointestinal stromal tumors and mast cell disease, molecular therapies targeting KIT mutations are being developed. In acute myeloid leukemia (AML), genome profiling via next-generation sequencing has shown that several genes that are mutated in patients with AML impact patients’ prognosis. Moreover, it was suggested that precision-medicine-based treatment using genomic data will improve treatment outcomes for AML patients. This paper presents (1) previous studies regarding the role of KIT mutations in AML, (2) the data in AML with KIT mutations from the HM-SCREEN-Japan-01 study, a genome profiling study for patients newly diagnosed with AML who are unsuitable for the standard first-line treatment (unfit) or have relapsed/refractory AML, and (3) new therapies targeting KIT mutations, such as tyrosine kinase inhibitors and heat shock protein 90 inhibitors. In this era when genome profiling via next-generation sequencing is becoming more common, KIT mutations are attractive novel molecular targets in AML.

Efficacy and safety of regorafenib in Japanese patients with advanced gastrointestinal stromal tumors

BACKGROUND

Regorafenib is an oral multi-kinase inhibitor that has been established as third-line treatment for patients after the failure of imatinib and sunitinib. However, since clinical data of regorafenib in the Japanese population are still lacking, the management of regorafenib is mainly based on the clinical experience of each oncologist. The aim of this study was to evaluate the efficacy and safety of regorafenib in a Japanese population.

METHODS

Thirty-three patients treated with regorafenib for metastatic and recurrent gastrointestinal stromal tumors were retrospectively enrolled. This study investigated the anti-tumor effect, including overall survival, progression-free survival, and safety, which was evaluated based on the incidence of adverse events.

RESULTS

The median overall survival of patients treated with regorafenib was 23.8 months and the 1-year overall survival rate was 80.0%, the median progression-free survival was 7.1 months and the 1-year progression-free survival rate was 40.2%. The responses to regorafenib were partial response in 3 cases (9.1%), stable disease in 17 (51.5%), progressive disease in 10 (30.3%), and non-evaluable in 3 (9.1%). The disease control rate was 54.0%. Treatment-related adverse events were reported in all patients, with the most common being hand-foot syndrome (72.7%), followed by liver damage (36.4%) and diarrhea (27.3%), and six patients (20.0%) were discontinued due to adverse events.

CONCLUSION

This is the first report of Japanese patients with gastrointestinal stromal tumors treated with regorafenib. Regorafenib showed efficacy and a manageable safety profile in Japanese patients with advanced gastrointestinal stromal tumors, which was comparable with previous studies.

Phase Ib Trial of the Combination of Imatinib and Binimetinib in Patients with Advanced Gastrointestinal Stromal Tumors

PURPOSE

This phase Ib trial was designed to evaluate the safety and early efficacy signal of the combination of imatinib and binimetinib in patients with imatinib-resistant advanced gastrointestinal stromal tumors (GISTs).

PATIENTS AND METHODS

This trial used a standard 3 + 3 design to determine the recommended phase II dose (RP2D). Additional patients were enrolled on an expansion cohort at the RP2D enriching for succinate dehydrogenase (SDH)-deficient GISTs to explore potential efficacy.

RESULTS

The trial enrolled nine patients in the dose-escalation cohort and 14 in the dose-expansion cohort including six with SDH-deficient GISTs. Imatinib 400 mg daily with binimetinib 45 mg twice daily was established as the RP2D. Dose-limiting toxicity (DLT) was asymptomatic grade 4 creatinine phosphokinase (CPK) elevation. The most common non-DLT grade 3/4 toxicity was asymptomatic CPK elevation (69.6%). Other common ≥grade 2 toxicities included peripheral edema (17.4%), acneiform rash (21.7%), anemia (30.4%), hypophosphatemia (39.1%), and aspartate aminotransferase (AST) increase (17.4%). Two serious adverse events occurred (grade 2 dropped head syndrome and grade 3 central retinal vein occlusion). No unexpected toxicities were observed. Limited clinical activity was observed in KIT-mutant GIST. For SDH-deficient GISTs, one of five had confirmed RECIST1.1 partial response (PR). The median progression-free survival (mPFS) in patients with SDH-deficient GIST was 45.1 months [95% confidence interval (CI), 15.8-not estimable (NE)]; the median overall survival (mOS) was not reached (95% CI, 31.6 months-NE). One patient with a refractory metastatic SDH-deficient GIST had an exceptional pathologic response and durable clinical benefit.

CONCLUSIONS

The combination of imatinib and binimetinib is safe with manageable toxicity and has encouraging activity in SDH-deficient but not imatinib-refractory KIT/PDGFRA-mutant GISTs. The observed clinical benefits provide a motivation for a larger trial of the combination strategy in SDH-deficient GISTs.

Gastrointestinal stromal tumors with Kit gene mutation in 4 guinea pigs (Cavia porcellus)

Gastrointestinal stromal tumors (GISTs) have been rarely reported in guinea pigs. We aimed to characterize the clinical and pathological features of GISTs in 4 guinea pigs and investigate the presence of mutations in exon 11 of the KIT proto-oncogene receptor tyrosine kinase (Kit) gene. Two subjects were male and 2 were female; 2 were 6 years old, 1 was 7 years old, and 1 was of an unknown age. Three cases had primary gastric tumors, whereas 1 had a primary small intestinal tumor. All cases had tumors that extended from the submucosa to the serosa with extraluminal growth. A gastric tumor had gastric, pancreatic, and cecal metastases. Histologically, the tumors were sharply demarcated and composed of spindle cells arranged in bundles, intermixed with small amounts of collagenous stroma. The tumor cells had mild atypia with few mitotic figures (0-5/50 high power fields, 7.95 mm²) and were immunolabeled for KIT and Discovered-on-GIST 1 (DOG1). All cases had mutations in exon 11 of the Kit gene. These findings indicate that GISTs in guinea pigs are similar to those in humans and dogs. GISTs in guinea pigs are potentially malignant submucosal tumors with KIT- and DOG1-immunolabeling, exon 11 KIT mutations, and the possibility of metastasis.

Patient demographics, clinicopathologic features, and outcomes in wild-type gastrointestinal stromal tumor: a national cohort analysis

Wild-type KIT and PDGFRA gastrointestinal stromal tumors (GIST) are rare tumors with limited treatment options. We sought to determine the clinicopathologic features of wild-type GIST and identify factors that influence overall survival (OS) using a large national database. Retrospective evaluation of patients with wild-type GIST in the National Cancer Database (NCDB) was performed. Demographic, clinicopathologic, and treatment data were analyzed. Features associated with OS were investigated using Kaplan-Meier analysis and Cox proportional hazards model. 244 patients with median diagnosis age of 59 years (95% CI 57-63) were identified. The stomach was the most common primary site (57%) followed by the small intestine (35%). Surgical resection was performed on 85% of patients and 53% of patients received systemic therapy. Factors associated with decreased OS on multivariable analysis included small intestine primary (HR 2.72, 95% CI 1.13-6.69, P = 0.026) and > 5 mitoses per 50 HPF (HR 4.77, 95% CI 1.86-13.2, P = 0.001). Wild-type GISTs may be identified in older patients, with most arising in the stomach and small bowel. Surgery remains the principal treatment modality. Small intestine primary site and high mitotic count were associated with abbreviated OS.

Health-Related Quality of Life and Side Effects in Gastrointestinal Stromal Tumor (GIST) Patients Treated with Tyrosine Kinase Inhibitors: A Systematic Review of the Literature

BACKGROUND

The introduction of tyrosine kinase inhibitors (TKIs) has revolutionized the treatment of gastrointestinal stromal tumors (GISTs), resulting in a substantial gain in median overall survival. Subsequently, health-related quality of life (HRQoL) has become more relevant. Here, we systematically review the available literature on HRQoL issues and side effects of different TKIs registered for the treatment of GIST.

METHODS

A search through five databases was performed. Full reports in English describing HRQoL outcomes and/or side effects in GIST patients on TKI therapy were included.

RESULTS

A total of 104 papers were included; 13 studies addressed HRQoL, and 96 studies investigated adverse events. HRQoL in patients treated with imatinib, regorafenib, and ripretinib remained stable, whereas most sunitinib-treated patients reported a decrease in HRQoL. Severe fatigue and fear of recurrence or progression were specifically assessed as HRQoL issues and had a negative impact on overall HRQoL as well as psychological and physical well-being. The majority of studies focused on physician-reported side effects. Nearly all GIST patients treated with a TKI experienced at least one adverse event, mostly mild to moderate.

CONCLUSIONS

Despite the fact that almost all patients treated with a TKI experienced side effects, this did not seem to affect overall HRQoL during TKI therapy. In daily practice, it are the side effects that hamper a patient's HRQoL resulting in treatment adjustments, suggesting that the reported side effects were underestimated by physicians, or the measures used to assess HRQoL do not capture all relevant issues that determine a GIST patient's HRQoL.

Switch Pocket Kinase: An Emerging Therapeutic Target for the Design of Anticancer Agents

Protein kinases are amongst the most focused enzymes in current century to design, synthesize and formulate drugs ought to be effective in the treatment of various disordered and diseased states involving either overexpression or deficiency situations. The ATP pocket on the kinases is the binding active site for most of the kinase inhibitors. However, the kinase mutations prevent the binding of kinase inhibitors to ATP pocket. The switch pocket site on this enzyme when occupied by switch pocket inhibitors, the enzyme become inactive even in the mutated state. This review comprises the detailed information on various classical protein kinases and switch pocket kinase inhibitors with their mechanism of action so that new molecules can be designed to encounter mutations in the kinase enzyme.

Phase II Trial of Imatinib Plus Binimetinib in Patients With Treatment-Naive Advanced Gastrointestinal Stromal Tumor

PURPOSE

Dual targeting of the gastrointestinal stromal tumor (GIST) lineage-specific master regulators, ETV1 and KIT, by MEK and KIT inhibitors were synergistic preclinically and may enhance clinical efficacy. This trial was designed to test the efficacy and safety of imatinib plus binimetinib in first-line treatment of GIST.

METHODS

In this trial (NCT01991379), treatment-naive adult patients with confirmed advanced GISTs received imatinib (400 mg once daily) plus binimetinib (30 mg twice daily), 28-day cycles. The primary end point was RECIST1.1 best objective response rate (ORR; complete response plus partial response [PR]). The study was designed to detect a 20% improvement in the ORR over imatinib alone (unacceptable rate of 45%; acceptable rate of 65%), using an exact binomial test, one-sided type I error of 0.08 and type II error of 0.1, and a planned sample size of 44 patients. Confirmed PR or complete response in > 24 patients are considered positive. Secondary end points included Choi and European Organisation for Research and Treatment of Cancer Response Rate, progression-free survival (PFS), overall survival (OS), pathologic responses, and toxicity.

RESULTS

Between September 15, 2014, and November 15, 2020, 29 of 42 evaluable patients with advanced GIST had confirmed RECIST1.1 PR. The best ORR was 69.0% (two-sided 95% CI, 52.9 to 82.4). Thirty-nine of 41 (95.1%) had Choi PR approximately 8 weeks. Median PFS was 29.9 months (95% CI, 24.2 to not estimable); median OS was not reached (95% CI, 50.4 to not estimable). Five of eight patients with locally advanced disease underwent surgery after treatment and achieved significant pathologic response (≥ 90% treatment effect). There were no unexpected toxicities. Grade 3 and 4 toxicity included asymptomatic creatinine phosphokinase elevation (79.1%), hypophosphatemia (14.0%), neutrophil decrease (9.3%), maculopapular rash (7.0%), and anemia (7.0%).

CONCLUSION

The study met the primary end point. The combination of imatinib and binimetinib is effective with manageable toxicity and warrants further evaluation in direct comparison with imatinib in frontline treatment of GIST.

Diagnosing gastrointestinal stromal tumors: The utility of fine-needle aspiration cytology versus biopsy

Background

Gastrointestinal stromal tumors (GIST) are mesenchymal tumors in the intestinal tract originating from a precursor to the interstitial cells of Cajal, which plays a role in gastric motility. The preoperative diagnosis of GIST may be very important for the surgical approach or the need for neoadjuvant treatment and is often done in conjunction with molecular testing.

Design

GISTs diagnosed in Stockholm between 1999 and 2019 with biopsy and/or fine‐needle aspiration (FNA) material were included. Clinical and tumor characteristics, as well as sample representability, ancillary techniques, diagnostic accuracy, and time to diagnosis, were categorized and compared.

Results

We identified 460 diagnostic samples from 347 patients, consisting of 212 biopsies and 248 FNAs. FNA cytology had a significantly (p < 0.05) better sample representability (92% vs. 77%), diagnostic accuracy (84% vs. 76%), and shorter time to diagnosis (4.5 vs. 12.3 days on average) in comparison with biopsies. In addition, ancillary techniques such as immunochemistry and molecular analysis for KIT and PDGFRA mutations could satisfactorily be performed on FNA materials.

Conclusions

There are advantages to both biopsy and FNA cytology in diagnosing GISTs. While the significantly shorter time to diagnosis for FNA cytology can be due to institutional differences, its many strengths make it both an accurate and time‐efficient method for preoperative diagnosis of GIST.