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

Characteristics and therapeutic strategies for familial gastrointestinal stromal tumors

This editorial discusses Wang et al's article on familial gastrointestinal stromal tumors (GISTs). We read with great interest this article concerning the diagnosis, treatment, and post-treatment management of patients with familial GISTs. The actual incidence of GISTs may be underestimated due to diagnostic limitations and the long-term low-risk behavior of some GISTs. The molecular landscape of GISTs is primarily driven by mutations in the KIT and platelet-derived growth factor receptor alpha (PDGFRA) genes. A subset of GISTs without these mutations known as wild-type GISTs, may harbor other rare mutations, impacting their response to targeted therapies. Clinically, patients with GISTs present with non-specific symptoms, often leading to delayed diagnosis. Genetic predispositions in familial GISTs provide insights into the genetic architecture and extragastrointestinal manifestations of GISTs. Management has evolved from surgical interventions to molecular-based therapies using tyrosine kinase inhibitors. The management of GISTs, especially in familial cases, requires a multidisciplinary approach. Cases of different gene mutations were reported in the same family, suggesting that incorporating genetic testing into routine clinical practice is crucial for the early identification of high-risk individuals and the implementation of tailored surveillance programs.

Gastric Leiomyosarcoma Completely Resected by Endoscopic Submucosal Dissection after a Precise Preoperative Diagnosis

A 68-year-old woman was diagnosed with leiomyosarcoma (LMS) based on preoperative biopsy of the gastric body. As tumor invasion confined to the submucosa with no breaking of the submucosal layer was confirmed on endoscopic ultrasonography (EUS), the patient underwent endoscopic submucosal dissection (ESD) for gastric LMS, resulting in complete tumor resection. No apparent recurrence was observed in the 2.5 years after treatment. This is an extremely rare case of gastric LMS that underwent ESD after a precise preoperative diagnosis, with no signs of recurrence after treatment. ESD may be an acceptable option for gastric LMS when EUS findings allow this treatment method.

Gastrointestinal Stromal Tumors

PURPOSE OF REVIEW

This review aims to outline the current understanding of the molecular drivers and treatment paradigms of gastrointestinal stromal tumors, with a focus on recent developments in treatment in the advanced disease setting.

RECENT FINDINGS

There have been recent advancements in our understanding of the molecular biology of gastrointestinal stromal tumors, including the identification of new genetic drivers and complex resistance mechanisms. We review the most recent findings in these areas, focusing on how new research insights are reshaping treatment strategies. Recent advancements in our understanding of the biology and treatment of GIST are paving the way for more personalized and effective therapeutic options. As knowledge of rare molecular subtypes, resistance mechanisms, and novel genomic techniques grows, new approaches are emerging in an effort to improve patient outcomes.

LINC00870 promotes imatinib resistance in gastrointestinal stromal tumor via inhibiting PIGR glycosylation modifications

Imatinib is the first-line targeted therapy for gastrointestinal stromal tumor (GIST), but resistance frequently occurs during treatment, limiting its efficacy and clinical application. We performed high-throughput sequencing of tissue specimens from imatinib-resistant GIST patients, and identified significantly high expression of polymeric immunoglobulin receptor (PIGR) in imatinib-resistant cell lines. Further investigation revealed that PIGR binds specifically to LINC00870. The findings from in vitro cell functional experiments provide evidence of a strong association between LINC00870 and PIGR and the processes of proliferation and metastasis in GIST. Overexpression of LINC00870 in GIST significantly inhibits the glycosylation modification and secretion of the extracellular region of PIGR, leading to immune dysregulation. The inhibition of PIGR or LINC00870 effectively surmounts imatinib resistance. Our study identified PIGR as a critical molecule in regulating GIST imatinib resistance and elucidated the mechanism by which PIGR promotes imatinib resistance through LINC00870 inhibition of PIGR glycosylation modifications. These findings provide a new theoretical basis for blocking drug resistance and improving prognosis in GIST.

Impact of Mutation Profile on Outcomes of Neoadjuvant Therapy in GIST

BACKGROUND

Neoadjuvant imatinib therapy plays a crucial role in the management of gastrointestinal stromal tumors (GISTs), but its impact across various mutational profiles remains uncertain.

OBJECTIVE

The aim of this study is to describe the clinicopathological features and to assess the response and surgical outcomes of neoadjuvant imatinib in GIST patients exhibiting diverse mutational profiles.

METHODS

We conducted a retrospective study, extracting data from the Dutch GIST Registry, including patients treated with neoadjuvant imatinib. Response rate was the primary outcome, and secondary outcomes were the time on neoadjuvant treatment and resection margins (R0 vs. R1/R2), respectively.

RESULTS

Between 2009 and 2021, 326 patients were treated with neoadjuvant imatinib, of which 264 (80.9%) underwent resection. A total of 197 (74.6%) of them had a KIT-exon 11 mutation, 19 (7.3%) had other KIT mutations, 10 (3.8%) had PDGFRA D842 mutations, 21 (6.8%) had other PDGFRA mutations, 2 (0.7%) had NTRK mutation, 1 (0.4%) had an SDH mutation, and 17 (6.4%) had WT GISTs. Patients with KIT-exon 11 mutations demonstrated a higher rate of partial response to imatinib (60.5% vs. 33.3%; p = 0.00). A positive resection margin (R1 or R2) was observed in 14 (21.2%) patients with a non-KIT exon 11 mutations and in 11 (5.5%) patients with a KIT-exon 11 mutation (p = 0.00). Moreover, non-KIT exon 11 mutation patients had a shorter median duration of neoadjuvant therapy (5.3 months, range 0.5-21.0) compared to patients with a KIT exon 11 mutation (8.8 months, range 0.2-31.3; p < 0.001).

CONCLUSIONS

Our study highlights the variability in treatment response associated with different GIST mutational profiles. Patients with a KIT-exon-11 mutation tended to respond more favorably to neoadjuvant imatinib in terms of partial response and surgical outcomes.

Case report: Clinical and molecular features of renal gastrointestinal tumor

While gastrointestinal stromal tumors (GISTs) often arise within the GI tract, it is well known that GISTs may also rarely emanate outside of the digestive system. Prior case reports have documented various primary sites in non-GI organs [extra-intestinal GIST (EGIST)], yet only one report has described a localized GIST of renal origin. Here, we describe a patient who presented with bilateral renal masses who was found to have a large unresectable renal GIST tumor treated with imatinib. We discuss treatment experience and response with systemic therapy and describe molecular data to contextualize this ultra-rare presentation within the landscape of EGIST tumors.

SHP2 inhibition and adjuvant therapy synergistically target KIT-mutant GISTs via ERK1/2-regulated GSK3β/cyclin D1 pathway

BACKGROUND

Most gastrointestinal stromal tumours (GISTs) are driven by KIT proto-oncogene, receptor tyrosine kinase (KIT). Targeted treatment with imatinib has been successful in primary GIST patients. However, resistance and relapse gradually develop due to secondary KIT mutations. Identifying novel therapeutic targets for advanced GIST with KIT mutants is critical.

METHODS

Clustered regularly interspaced palindromic repeats (CRISPR)/Cas9 gene editing, immunoblotting, immunoprecipitation and cell-based assays were used to characterise the role of Src homology region 2 domain-containing phosphatase 2 (SHP2) in GIST. Immunoblotting, cell cycle analysis, transcriptome analysis and rescue experiments were performed to investigate the molecular mechanisms underlying SHP2 inhibition. Synergistic effects of SHP2 inhibition with approved KIT tyrosine kinase inhibitors (TKIs) were demonstrated using cell proliferation assay, spheroid formation assay, cell cycle analysis and immunoblotting. The combination of SHP2 inhibition and imatinib was further evaluated in GIST mouse models.

RESULTS

In KIT-mutant GIST, SHP2 was hyperactive and coprecipitated with KIT. Activated SHP2 transduced signals from KIT to the downstream MAPK/ERK pathway. SHP2 inhibition significantly reduced cell viability and arrested cell at G0/G1 phase in GIST cells. Mechanistically, SHP2 regulated the MAPK/ERK, GSK3β/cyclin D1 and mTORC1 pathways in GIST. Specifically, SHP2 inhibition relieved GSK3β self-inhibition, leading to a reduction in cyclin D1 via phosphorylation at Thr286 and subsequent G0/G1 cell cycle arrest. Rescue experiments confirmed that cyclin D1 is functional and critical for cell proliferation. Additionally, SHP2 inhibition synergised with approved KIT TKIs in inhibiting GIST cells. In GIST mouse models, SHP2 inhibitor (SHP099) combined with imatinib significantly inhibited proliferation of imatinib-sensitive and -insensitive GIST cells.

CONCLUSIONS

SHP2 functioned as a key signal transducer for the MAPK/ERK signalling pathway and regulated the cell cycle through GSK3β/cyclin D1/Rb pathway. SHP2 inhibition demonstrates significant efficacy towards GIST cells and synergises with approved TKIs. Therefore, SHP2 represents a promising therapeutic target for advanced GIST.

KEY POINTS

SHP2 plays a pivotal role as a signal transducer in the MAPK/ERK signaling pathway. SHP2 controls the cell cycle via the GSK3β/cyclin D1/Rb pathway in oncogenic KIT-driven GIST. Inhibition of SHP2 synergizes with adjuvant therapy drugs in inhibiting KIT-driven GIST with primary and secondary mutations both in vitro and in vivo.

A Review of Genomic Testing and SDH- Deficiency in Gastrointestinal Stromal Tumors: Getting to the GIST

Gastrointestinal Stromal Tumors (GISTs) have seen significant advancements in their diagnosis and management, driven by targeted therapeutic development and molecular testing. The identification of mutations in genes such as KIT and PDGFRA has transformed treatment approaches, particularly through targeted therapies like imatinib, which have improved patient outcomes. This review explores the critical role of genomic testing in GIST, highlighting its importance in accurate diagnosis, treatment planning, and long-term surveillance for KIT/PDGFRA negative, SDH-deficient GISTs. SDH-deficient GISTs arise from mutations or epigenetic changes affecting the succinate dehydrogenase complex. The complexity of SDH-deficient GISTs, including their association with hereditary syndromes such as Hereditary Paraganglioma-Pheochromocytoma and/or hypermethylation of the SDHC promoter, underscores the need for comprehensive germline testing. Despite the availability of guidelines, variability exists in genomic testing recommendations across different regions, necessitating a unified approach. This review proposes a simplified algorithm for the genomic workup of GIST, and suggests all individuals with SDH-deficient GIST, regardless of germline testing result, require monitoring for additional SDHx-related tumors, given the lack of widely available methylation and full gene SDHA analysis.

18F-Fluorodeoxyglucose Uptake in PDGFRA-Mutant Gastrointestinal Stromal Tumors

Importance

The D842V platelet-derived growth factor receptor α (PDGFRA) mutation identifies a molecular subgroup of gastrointestinal stromal tumors (GISTs), primarily resistant to standard tyrosine kinase inhibitors and with an overall more indolent behavior. Although functional imaging with 18F-fluorodeoxyglucose-labeled positron emission tomography ([18F]FDG-PET) plays a proven role in GISTs, especially in early assessment of tumor response, less is known about [18F]FDG uptake according to the GIST molecular subtypes.

Objective

To evaluate the degree of [18F]FDG uptake in PDGFRA-mutant GISTs and better define the role of functional imaging in this rare and peculiar subset of GISTs.

Design, Setting, and Participants

This multi-institutional retrospective cohort study involving 7 GIST reference centers in Italy included patients with PDGFRA-mutant GIST who underwent [18F]FDG-PET from January 1, 2000, to December 31, 2023. Data on the maximum standardized uptake value (SUVmax) of primary tumor or metastatic disease were collected.

Exposure

PDGFRA-mutant GIST and [18F]FDG-PET.

Main Outcome and Measure

The primary outcome was the degree of [18F]FDG uptake of PDGFRA-mutant GISTs, with a focus on the D842V-mutant subgroup. Secondary objectives were to assess the association between the degree of [18F]FDG uptake and main clinicopathologic features.

Results

A total of 71 patients with PDGFRA-mutant GISTs were included in the analysis: 37 (52.1%) in the D842V subgroup (group A) and 34 (47.9%) in the non-D842V subgroup (group B). Additionally, 70 patients with KIT exon 11-mutant GIST served as a control group (group C). For all 141 participants, the median age at diagnosis was 59 (range, 26-89) years, and 81 patients (57.4%) were male. Overall, the median SUVmax was 4.4 (IQR, 0-10.1), while the median SUVmax for group A was 0 (IQR, 0-3.2); for group B, 3.6 (IQR, 0-5.1); and for group C, 10.1 (IQR, 5.1-13.9). The median SUVmax of PDGFRA-mutant GISTs was significantly lower than the median value of KIT exon 11-mutant GISTs (0 [IQR, 0-4.3] vs 10.1 [IQR, 5.1-14.0]; P < .001). Median [18F]FDG uptake was significantly lower in the D842V subgroup compared with the non-D842V subgroup (0 [IQR, 0-3.2] vs 3.6 [IQR, 0-5.1]; P = .02). Moreover, the triad of gastric primary tumor, tumor size greater than 10 cm, and SUVmax of 5.75 or less was associated with identification of PDGFRA-mutant GISTs.

Conclusions and Relevance

In this cohort study of patients with PDGFRA-mutant GISTs, the D842V-mutant GISTs were associated with an overall lower [18F]FDG uptake compared with other GIST subgroups. Therefore, the role of functional imaging with [18F]FDG-PET in this subset of GISTs may be limited and should be further explored for its potential prognostic and predictive value.

Ileal Gastrointestinal Stromal Tumor (GIST) Presenting With a Liver Abscess: A Case Report and Review of the Literature

Gastrointestinal stromal tumors (GISTs) are rare small intestinal tumors. Due to challenging diagnoses, the majority of patients typically report chronic problems. Early diagnosis and the start of appropriate treatment depend on high suspicion. We present a case of a 47-year-old male patient who first experienced fever, nausea, vomiting, and pain in the right upper quadrant. Radiologic examinations showed an intra-abdominal tumor containing oral contrast and a liver lesion, indicating gastrointestinal tract involvement. He had an ileal GIST that created a fistula between the tumor and the small intestine, complicated by a liver abscess. We surgically removed the tumor and intra-operatively drained the liver abscess. A liver lesion found in conjunction with a small intestine GIST should cause concern for both the possibility of infectious complications such as a pyogenic liver abscess and metastatic illness. The uncommon appearance of an ileal GIST with a tumor-intestinal fistula, accompanied by a liver abscess, is reviewed in this case report.

Novel structural variants that impact cell cycle genes are elucidated in metastatic gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasm of the digestive tract. Despite multiple therapeutic advances, patients with advanced disease frequently develop resistance to tyrosine kinase inhibitors (TKIs), and therefore represent a therapeutic challenge. We employed whole genome sequencing (WGS) on three metastatic GISTs refractory to various TKIs and explored a publicly available cohort of 499 GISTs. This study sheds light on the clinical importance of alterations in cell cycle genes such as cyclin-dependent kinase 2 A (CDKN2A), and cyclin-dependent kinase 2B (CDKN2B), their frequent alteration in metastatic GISTs and their potential role in tumor progression of this neoplasm. Likewise, new structural variations were identified in cyclin-dependent kinase 12 (CDK12). Whole genome profiling of metastatic GIST provides new insights to advance precision care of the disease, focusing on new therapeutic possibilities, especially for emerging targets such as CDK12.

Colonic leiomyosarcoma with lung metastasis or lung cancer: A case report

Colonic leiomyosarcoma is a tumor with a very low incidence and a high metastasis rate, mainly lung metastasis. This report provides insights into the future treatment. Thoracic puncture is necessary for patients with pulmonary nodules.

Fourteen-year follow-up results of imatinib therapy in patients with unresectable and metastatic gastrointestinal stromal tumors

BACKGROUND

Imatinib therapy is the gold standard for the treatment of unresectable and metastatic gastrointestinal stromal tumors (GISTs). However, few studies have reported the long-term outcomes of the treatment.

METHODS

Seventy patients who underwent imatinib therapy for unresectable and metastatic GISTs were enrolled between 2001 and 2009, and follow-up data were collected until October 2023. One hundred and sixty-eight months had passed since the final enrollment. The outcome measures were patient survival and the status of GIST and imatinib therapy. The cumulative incidence of disease progression (PD) and the chronological changes in PD hazard rate (HR) were also analyzed.

RESULTS

The 5-, 10-, 15-, and 20-year overall survival rates were 64.3%, 30.0%, 16.8%, and 12.2%, respectively. Sixty of the 70 enrolled patients died before the data cutoff date: 47 (78.3%) patients died of GIST progression while the remaining 13 (21.7%) died of diseases other than GISTs. The cumulative incidence of PD logarithmically increased, and PD continued even after 10 years of treatment. PD HR decreased over time to reach the lowest value at 9.6 years after the initiation of treatment (HR 0.00027; 95% CI 0.00007-0.00174) and after that formed a small peak at 13 years (HR 0.00144; 95% CI 0.00043-0.00436).

CONCLUSIONS

Imatinib therapy showed high clinical efficacy in terms of long-term survival in GIST patients. However, patients undergoing imatinib therapy were at continuous risk of PD even after the 10-year treatment. Long-term treatment and follow-up beyond 10 years are necessary for unresectable and metastatic GIST patients.

An ultrasound based method for predicting the malignant potential of primary gastrointestinal stromal tumors preoperatively

OBJECTIVE

Gastrointestinal stromal tumors (GISTs) are difficult to identify the risk level accurately without surgical pathological confirmation. The purpose of our study was to propose a noninvasive prediction method for predicting the malignant potential of GISTs preoperatively by using contrast-enhanced ultrasound (CEUS) with gastric distention.

METHODS

We reviewed 47 GISTs who underwent CEUS from April 2017 to August 2023 retrospectively, all the lesions were certificated by pathology after surgery. The age of the patient, size of the lesion, shape, necrosis, calcification in the lesion, perfusion parameters including arrival time (AT), peak intensity (PI), time to peak (TTP), and area under the curve (AUC) of the lesion and surrounding normal tissue were analyzed. Logistic regression analyses were performed. Of the 47 GISTs, 26 were high-risk and 21 low-risk tumors respectively.

RESULTS

Compared with low-risk GISTs, high-risk GIST had faster AT (7.7s vs. 11.5s, p < 0.05), higher PI (15.2dB vs. 12.5dB, p < 0.05), and larger size (4.4 cm vs. 2.2 cm, p < 0.001). In multivariate logistic regression, AT, PI, and size were significant features. The corresponding regression equation In (p/(1-p)=-5.9 + 4.5 size + 4.6 PI + 4.0 AT).

CONCLUSION

The size, AT, and PI of the GISTs on CEUS can be used as parameters for a noninvasive risk level prediction model of GISTs. This model may help identify the different risk levels of GISTs before surgery.

Genomic and transcriptomic landscape of human gastrointestinal stromal tumors

Gastrointestinal stromal tumor (GISTs) are clinically heterogenous exhibiting varying degrees of disease aggressiveness in individual patients. We comprehensively describe the genomic and transcriptomic landscape of a cohort of 117 GISTs including 31 low-risk, 18 intermediate-risk, 29 high-risk, 34 metastatic and 5 neoadjuvant GISTs from 105 patients. GISTs have notably low tumor mutation burden but widespread copy number variations. Aggressive GISTs harbor remarkably more genomic aberrations than low-/intermediate-risk GISTs. Complex genomic alterations, chromothripsis and kataegis, occur selectively in aggressive GISTs. Despite the paucity of mutations, recurrent inactivating YLPM1 mutations are identified (10.3%, 7 of 68 patients), enriched in high-risk/metastatic GIST and functional study further demonstrates YLPM1 inactivation promotes GIST proliferation, growth and oxidative phosphorylation. Spatially and temporally separated GISTs from individual patients demonstrate complex tumor heterogeneity in metastatic GISTs. Finally, four prominent subtypes are proposed with different genomic features, expression profiles, immune characteristics, clinical characteristics and subtype-specific treatment strategies. This large-scale analysis depicts the landscape and provides further insights into GIST pathogenesis and precise treatment.

Gastrointestinal Stromal Tumors: Variants and Some Pitfalls That They Create

The diagnosis of gastrointestinal stromal tumors (GISTs) is generally straightforward using a combination of histologic evaluation and pertinent immunohistochemical staining with CD117/kit and DOG-1 (discovered on GIST) antibodies. However, this tumor can be challenging in cases with an unusual morphology, in limited biopsies, for those in uncommon sites, post-treatment, and when other neoplasms express CD117/kit and DOG-1, thereby mimicking GIST. Finding epithelioid GISTs in the stomach in younger patients should prompt testing for succinate dehydrogenase (SHD)-deficiency using immunohistochemical staining for subunit B (SDHB). However, SDH-deficient GISTs can also arise in older patients, or as part of the Carney triad or Carney-Stratakis syndrome. GISTs with PDGFRA mutations can also prove difficult if they lack kit expression. It is also important to consider morphologic and immunophenotypic changes associated with treatment, including the potential absence of kit expression, particularly in GISTs that have metastasized. Therefore, obtaining clinical information regarding prior therapy with a tyrosine kinase inhibitor (TKI) is crucial.

Gastrointestinal Stromal Tumor of the Rectum: Report of a Case With Long-Term Imatinib Treatment

Gastrointestinal stromal tumors (GIST) are rare in the rectum. These usually present with symptoms produced by compression of pelvic organs or bleeding. Surgery is the treatment of choice, however, at times the surgery can be mutilating and organ preservation may not be possible. In such cases imatinib can be used. We report a case of rectal GIST that presented with urinary obstruction and obstipation treated with long-term imatinib with very good response and relief of symptoms, which prompted the patient to refuse surgery and resulted in organ preservation.

Current Drug Resistance Mechanisms and Treatment Options in Gastrointestinal Stromal Tumors: Summary and Update

OPINION STATEMENT

Gastrointestinal stromal tumor (GIST) is characterized by well-defined oncogenes. Despite the significant improvement in treatment outcomes with adjuvant imatinib therapy for patients, drug resistance remains a major challenge for GIST therapy. This review focuses on the mechanisms contributing to drug resistance phenotype in GIST, such as primary imatinib-resistant mutants, secondary mutations, non-covalent binding of TKI to its target, tumor heterogeneity, re-activation of pro-survival/proliferation pathways through non-KIT/PDGFRA kinases, and loss of therapeutic targets in wild-type GIST. Corresponding suggestions are proposed to overcome drug-resistance phenotype of GIST. This review also summarizes the suitability of currently approved TKIs on different KIT/PDGFRA mutations and updates related clinical trials. Recent potent drugs and emerging strategies against advanced GISTs in clinical trials are presented. Additionally, metabolic intervention offers a new avenue for clinical management in GIST. A landscape of metabolism in GIST and metabolic changes under imatinib treatment are summarized based on currently published data. The OXPHOS pathway is a promising therapeutic target in combination with TKI against sensitive KIT/PDGFRA mutants. Comprehensive understanding of the above resistance mechanisms, experimental drugs/strategies and metabolic changes is critical to implement the proper therapy strategy and improve the clinical therapy outcomes for GIST.

True Mitotic Count Prediction in Gastrointestinal Stromal Tumors: Bayesian Network Model and PROMETheus (Preoperative Mitosis Estimator Tool) Application Development

BACKGROUND

Gastrointestinal stromal tumors (GISTs) present a complex clinical landscape, where precise preoperative risk assessment plays a pivotal role in guiding therapeutic decisions. Conventional methods for evaluating mitotic count, such as biopsy-based assessments, encounter challenges stemming from tumor heterogeneity and sampling biases, thereby underscoring the urgent need for innovative approaches to enhance prognostic accuracy.

OBJECTIVE

The primary objective of this study was to develop a robust and reliable computational tool, PROMETheus (Preoperative Mitosis Estimator Tool), aimed at refining patient stratification through the precise estimation of mitotic count in GISTs.

METHODS

Using advanced Bayesian network methodologies, we constructed a directed acyclic graph (DAG) integrating pertinent clinicopathological variables essential for accurate mitotic count prediction on the surgical specimen. Key parameters identified and incorporated into the model encompassed tumor size, location, mitotic count from biopsy specimens, surface area evaluated during biopsy, and tumor response to therapy, when applicable. Rigorous testing procedures, including prior predictive simulations, validation utilizing synthetic data sets were employed. Finally, the model was trained on a comprehensive cohort of real-world GIST cases (n=80), drawn from the repository of the Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Humanitas Research Hospital, with a total of 160 cases analyzed.

RESULTS

Our computational model exhibited excellent diagnostic performance on synthetic data. Different model architecture were selected based on lower deviance and robust out-of-sample predictive capabilities. Posterior predictive checks (retrodiction) further corroborated the model's accuracy. Subsequently, PROMETheus was developed. This is an intuitive tool that dynamically computes predicted mitotic count and risk assessment on surgical specimens based on tumor-specific attributes, including size, location, surface area, and biopsy-derived mitotic count, using posterior probabilities derived from the model.

CONCLUSIONS

The deployment of PROMETheus represents a potential advancement in preoperative risk stratification for GISTs, offering clinicians a precise and reliable means to anticipate mitotic counts on surgical specimens and a solid base to stratify patients for clinical studies. By facilitating tailored therapeutic strategies, this innovative tool is poised to revolutionize clinical decision-making paradigms, ultimately translating into improved patient outcomes and enhanced prognostic precision in the management of GISTs.

Detection of KIT Mutations in Systemic Mastocytosis: How, When, and Why

More than 90% of patients affected by mastocytosis are characterized by a somatic point mutation of KIT, which induces ligand-independent activation of the receptor and downstream signal triggering, ultimately leading to mast cell accumulation and survival. The most frequent mutation is KIT p.D816V, but other rarer mutations can also be found. These mutations often have a very low variant allele frequency (VAF), well below the sensitivity of common next-generation sequencing (NGS) methods used in routine diagnostic panels. Highly sensitive methods are developing for detecting mutations. This review summarizes the current indications on the recommended methods and on how to manage and interpret molecular data for the diagnosis and follow-up of patients with mastocytosis.

Impact of systemic steroids on the efficacy of first line imatinib treatment of patients with advanced gastrointestinal stromal tumors (GISTs)

BACKGROUND

Effective management of adverse events is required to maintain sufficient imatinib dosing when treating patients with gastrointestinal stromal tumors (GISTs). Skin rash is a common adverse event of imatinib, which can be effectively controlled by systemic steroid treatment without imatinib dose modification or interruption. However, the impact of the use of systemic steroids on the efficacy of imatinib treatment remains unclear.

METHODS

Between October 2014 and February 2022, 277 consecutive patients from a prospective registry of GIST patients were included as the study population. Patients who started systemic steroids due to grade ≥ 3 skin rash or grade 2 skin rash with grade 2 pruritis were classified as the steroid group, whereas patients who did not develop a skin rash or those who did not require steroids for a mild skin rash were classified as the control group. Efficacy outcomes were compared between the two groups.

RESULTS

Among the 277 patients, 30 (10.8%) were treated with systemic steroids for skin rash. There was no significant difference in progression free survival (PFS) or overall survival (OS) between the steroid and control groups (3-year PFS, 67.7% vs. 65.1%, p = 0.53; 3-year OS, 91% vs. 89.9%, p = 0.67, respectively). The use of systemic steroids was not an independent factor associated with PFS (hazard ratio 0.73, 95% confidence interval 0.36-1.49, p = 0.39) and OS (hazard ratio 0.37, 95% confidence interval 0.12-1.18, p = 0.09). In the steroid group, patients who successfully maintained the imatinib dosage showed a trend toward more favorable survival outcomes than those who did not (3-year PFS, 73.3% vs. 44.4%, p = 0.34; 3-year OS, 95.8% vs. 75.0%, p = 0.15, respectively).

CONCLUSIONS

The use of systemic steroids for the control of imatinib induced severe skin rash did not adversely affect the efficacy outcomes of imatinib in patients with advanced GIST.

A diagnostic challenge of KIT p.V559D and BRAF p.G469A mutations in a paragastric mass

A patient with gastrointestinal stroma tumor (GIST) and KIT p.V559D and BRAF p.G469A alterations was referred to our institutional molecular tumor board (MTB) to discuss therapeutic implications. The patient had been diagnosed with B-cell chronic lymphocytic leukemia (CLL) years prior to the MTB presentation. GIST had been diagnosed 1 month earlier. After structured clinical annotation of the molecular alterations and interdisciplinary discussion, we considered BRAF/KIT co-mutation unlikely in a treatment-naïve GIST. Discordant variant allele frequencies furthermore suggested a second malignancy. NGS of a CLL sample revealed the identical class 2 BRAF alteration, thus supporting admixture of CLL cells in the paragastric mass, leading to the detection of 2 alterations. Following the MTB recommendation, the patient received imatinib and had a radiographic response. Structured annotation and interdisciplinary discussion in specialized tumor boards facilitate the clinical management of complex molecular findings. Coexisting malignancies and clonal hematopoiesis warrant consideration in case of complex and uncommon molecular findings.

Intratumoral microbiome promotes liver metastasis and dampens adjuvant imatinib treatment in gastrointestinal stromal tumor

Understanding the determinants of long-term liver metastasis (LM) outcomes in gastrointestinal stromal tumor (GIST) patients is crucial. We established the feature selection model of intratumoral microbiome at the surgery, achieving robust predictive accuracies of 0.953 and 0.897 AUCs in discovery (n = 74) and validation (n = 34) cohorts, respectively. Notably, despite the significant reduction in LM occurrence with adjuvant imatinib (AI) treatment, intratumoral microbiome exerted independently stronger effects on post-operative LM. Employing both 16S and full-length rRNA sequencing, we pinpoint intracellular Shewanella algae as a foremost LM risk factor in both AI- and non-AI-treated patients. Experimental validation confirmed S. algae's intratumoral presence in GIST, along with migration/invasion-promoting effects on GIST cells. Furthermore, S. algae promoted LM and impeded AI treatment in metastatic mouse models. Our findings advocate for incorporating intratumoral microbiome evaluation at surgery, and propose S. algae as a therapeutic target for LM suppression in GIST.

Gastrointestinal stromal tumors in fine-needle aspiration biopsies

Gastrointestinal stromal tumors (GISTs), although rare, are the most common mesenchymal neoplasms of the gastrointestinal tract. Their potential for malignancy underscores the significance of identifying them through cytomorphologic findings and pertinent immunohistochemical markers. GISTs can emerge anywhere along the gastrointestinal tract with a predilection for the stomach. The clinical manifestations vary from nonspecific abdominal symptoms to incidental discovery during diagnostic interventions for unrelated signs and symptoms. Cytologically, GIST aspirates contain spindle or epithelioid cells with immunoreactivity for CD117/c-KIT, DOG-1, and CD34. Molecularly, KIT or PDGFRA mutations are prevalent, guiding targeted therapy with tyrosine kinase inhibitors. Distinct subtypes like succinate dehydrogenase-deficient GISTs pose challenges, often affecting younger individuals and displaying unique features. Histologically, GISTs are graded by mitotic rates, aiding prognostication. Distinguishing GISTs from similar entities is pivotal, necessitating attention to their immunostaining patterns for making an accurate diagnosis and molecular alterations for effectively planning treatment. Common differential diagnoses include leiomyoma, schwannoma, and solitary fibrous tumor. This article presents a classic GIST case and showcases relatively simple diagnostic clues for identifying similar lesions that may occur in diverse locations.

Comprehensive Genomic Assessment of Advanced-Stage GI Stromal Tumors Using the Japanese National Center for Cancer Genomics and Advanced Therapeutics Database

PURPOSE

Clinical utility of comprehensive genomic profiling (CGP) for precision medicine has become evident. Although there are several reports on the genomic landscape of GI stromal tumors (GISTs), large-scale data specific to GIST are limited, especially in Asia. Additionally, the applicability of molecular-targeted agents identified using CGP has not been extensively examined. We investigated the status of genomic alterations in Japanese patients with advanced GISTs using the National Center for Cancer Genomics and Advanced Therapeutics (C-CAT) database to identify novel treatment strategies and drug development.

MATERIALS AND METHODS

We retrospectively reviewed the clinical and CGP data of patients with advanced-stage GIST registered in the C-CAT database to assess the genomic landscape and potential actionable alterations.

RESULTS

Data from 144 patients were reviewed. Oncogenic alterations were detected frequently in KIT (78%), CDKN2A (37%), CDKN2B (29%), RB1 (11%), STK11 (10%), TP53 (9%), PDGFRA (6%), and SDHB (6%). Loss of CDKN2A/CDKN2B was only observed in KIT/PDGFRA-mutated GISTs, while alterations in SDHA/SDHB were only detected in KIT/PDGFRA wild-type GISTs. Among 119 KIT/PDGFRA-mutated GISTs, 95 (80%) had oncogenic genomic alterations and 29 (24%) had actionable alterations, excluding KIT and PDGFRA. However, among 25 KIT/PDGFRA wild-type GISTs, 22 (88%) had oncogenic alterations and 11 (44%) had actionable alterations. Representative candidate drugs for genome-matched therapies in KIT/PDGFRA-mutated and wild-type GISTs were as follows: pembrolizumab for tumor mutation burden-high in one and two patients, respectively; poly-adenosine diphosphate ribose polymerase inhibitors for alterations related to homologous recombination deficiency in 12 and one patient, respectively; NTRK inhibitor for ETV6-NTRK3 fusion in one with KIT/PDGFRA wild-type GIST; and human epidermal growth factor receptor 2-antibody-drug conjugate in one with KIT/PDGFRA-mutated GIST.

CONCLUSION

This study highlights the genomic landscape of advanced GISTs and the important role of CGP in identifying rational molecular-targeted therapeutic options.

c-KIT inhibitors reduce pathology and improve behavior in the Tg(SwDI) model of Alzheimer's disease

Treatments for Alzheimer's disease have primarily focused on removing brain amyloid plaques to improve cognitive outcomes in patients. We developed small compounds, known as BK40143 and BK40197, and we hypothesize that these drugs alleviate microglial-mediated neuroinflammation and induce autophagic clearance of neurotoxic proteins to improve behavior in models of neurodegeneration. Specificity binding assays of BK40143 and BK40197 showed primary binding to c-KIT/Platelet Derived Growth Factor Receptors (PDGFR)α/β, whereas BK40197 also differentially binds to FYVE finger-containing phosphoinositide kinase (PIKFYVE). Both compounds penetrate the CNS, and treatment with these drugs inhibited the maturation of peripheral mast cells in transgenic mice, correlating with cognitive improvements on measures of memory and anxiety. In the brain, microglial activation was profoundly attenuated and amyloid-beta and tau were reduced via autophagy. Multi-kinase inhibition, including c-KIT, exerts multifunctional effects to reduce neurodegenerative pathology via autophagy and microglial activity and may represent a potential therapeutic option for neurodegeneration.

Anti-tumor effect of antibody-drug conjugate targeting cell adhesion molecule 1 on GIST cells representing small intestinal GIST

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the alimentary tract. The prognosis depends on the primary site, and small intestinal GISTs have a worse prognosis than gastric GISTs. Molecularly targeted drugs to inhibit tyrosine kinase activity of KIT were used for unresectable or recurrent GISTs. However, secondary resistance to the drugs is often acquired, and treatments based on other mechanisms are needed. Previously, we reported that cell adhesion molecule 1 (CADM1) was highly expressed in most of small intestinal GISTs but not in most of gastric GISTs. In the present study, we examined whether the antibody-drug conjugate (ADC) with anti-CADM1 antibody and monomethyl auristatin E (anti-CAD-ADC) shows anti-tumor effect on CADM1-expressing human GIST cells. The ADC adhibited in this study was previously used for CADM1-expressing human mesothelioma cells and showed anti-tumor effect for them in vitro. GIST-T1 cell line of gastric origin which scarcely expresses CADM1 and GIST-T1 cells transfected with CADM1 cDNA (GIST-T1-CAD cells) which highly expresses CADM1 and represents small intestinal GIST were used. In vitro, anti-CAD-ADC showed remarkable cytotoxic activity on GIST-T1-CAD cells, but control ADC did not. Both anti-CAD-ADC and control ADC did not show anti-tumor effect on original GIST-T1 cells. When GIST-T1-CAD cells were subcutaneously injected to the nude mice, intravenous administration of anti-CAD-ADC showed inhibitory effect for tumor enlargement. Tumor of GIST-T1 cells grew even after anti-CAD-ADC injection. When GIST-T1-CAD cells were injected into peritoneal cavity of the SCID mice, intraperitoneal administration of anti-CAD-ADC showed reduction of the peritoneal tumor. On the other hand, peritoneal tumor grew after control ADC administration. Tissue and organ damage due to administration of anti-CAD-ADC was not apparent by macroscopic and histological examinations in mice. These results indicate that anti-CAD-ADC could have apparent anti-tumor effect on CADM1-expressing human GIST cells both in in vitro and in vivo mouse models.

Revolutionizing CAR T-Cell Therapies: Innovations in Genetic Engineering and Manufacturing to Enhance Efficacy and Accessibility

Chimeric antigen receptor (CAR) T-cell therapy has achieved notable success in treating hematological cancers but faces significant challenges in solid-tumor treatment and overall efficacy. Key limitations include T-cell exhaustion, tumor relapse, immunosuppressive tumor microenvironments (TME), immunogenicity, and antigen heterogeneity. To address these issues, various genetic engineering strategies have been proposed. Approaches such as overexpression of transcription factors or metabolic armoring and dynamic CAR regulation are being explored to improve CAR T-cell function and safety. Other efforts to improve CAR T-cell efficacy in solid tumors include targeting novel antigens or developing alternative strategies to address antigen diversity. Despite the promising preclinical results of these solutions, challenges remain in translating CAR T-cell therapies to the clinic to enable economically viable access to these transformative medicines. The efficiency and scalability of autologous CAR T-cell therapy production are hindered by traditional, manual processes which are costly, time-consuming, and prone to variability and contamination. These high-cost, time-intensive processes have complex quality-control requirements. Recent advancements suggest that smaller, decentralized solutions such as microbioreactors and automated point-of-care systems could improve production efficiency, reduce costs, and shorten manufacturing timelines, especially when coupled with innovative manufacturing methods such as transposons and lipid nanoparticles. Future advancements may include harmonized consumables and AI-enabled technologies, which promise to streamline manufacturing, reduce costs, and enhance production quality.

Shared germline genomic variants in two patients with double primary gastrointestinal stromal tumours (GISTs)

BACKGROUND

Gastrointestinal stromal tumours (GISTs) are prevalent mesenchymal tumours of the gastrointestinal tract, commonly exhibiting structural variations in KIT and PDGFRA genes. While the mutational profiling of somatic tumours is well described, the genes behind the susceptibility to develop GIST are not yet fully discovered. This study explores the genomic landscape of two primary GIST cases, aiming to identify shared germline pathogenic variants and shed light on potential key players in tumourigenesis.

METHODS

Two patients with distinct genotypically and phenotypically GISTs underwent germline whole genome sequencing. CNV and single nucleotide variant (SNV) analyses were performed.

RESULTS

Both patients harbouring low-risk GISTs with different mutations (PDGFRA and KIT) shared homozygous germline pathogenic deletions in both CFHR1 and CFHR3 genes. CNV analysis revealed additional shared pathogenic deletions in other genes such as SLC25A24. No particular pathogenic SNV shared by both patients was detected.

CONCLUSION

Our study provides new insights into germline variants that can be associated with the development of GISTs, namely, CFHR1 and CFHR3 deep deletions. Further functional validation is warranted to elucidate the precise contributions of identified germline mutations in GIST development.

Fibroblast Growth Factor 2 (FGF2) Activates Vascular Endothelial Growth Factor (VEGF) Signaling in Gastrointestinal Stromal Tumors (GIST): An Autocrine Mechanism Contributing to Imatinib Mesylate (IM) Resistance

We showed previously that the autocrine activation of the FGFR-mediated pathway in GIST lacking secondary KIT mutations was a result of the inhibition of KIT signaling. We show here that the FGF2/FGFR pathway regulates VEGF-A/VEGFR signaling in IM-resistant GIST cells. Indeed, recombinant FGF2 increased the production of VEGF-A by IM-naive and resistant GIST cells. VEGF-A production was also increased in KIT-inhibited GIST, whereas the neutralization of FGF2 by anti-FGF2 mAb attenuated VEGFR signaling. Of note, BGJ 398, pan FGFR inhibitor, effectively and time-dependently inhibited VEGFR signaling in IM-resistant GIST T-1R cells, thereby revealing the regulatory role of the FGFR pathway in VEGFR signaling for this particular GIST cell line. This also resulted in significant synergy between BGJ 398 and VEGFR inhibitors (i.e., sunitinib and regorafenib) by enhancing their pro-apoptotic and anti-proliferative activities. The high potency of the combined use of VEGFR and FGFR inhibitors in IM-resistant GISTs was revealed by the impressive synergy scores observed for regorafenib or sunitinib and BGJ 398. Moreover, FGFR1/2 and VEGFR1/2 were co-localized in IM-resistant GIST T-1R cells, and the direct interaction between the aforementioned RTKs was confirmed by co-immunoprecipitation. In contrast, IM-resistant GIST 430 cells expressed lower basal levels of FGF2 and VEGF-A. Despite the increased expression VEGFR1 and FGFR1/2 in GIST 430 cells, these RTKs were not co-localized and co-immunoprecipitated. Moreover, no synergy between FGFR and VEGFR inhibitors was observed for the IM-resistant GIST 430 cell line. Collectively, the dual targeting of FGFR and VEGFR pathways in IM-resistant GISTs is not limited to the synergistic anti-angiogenic treatment effects. The dual inhibition of FGFR and VEGFR pathways in IM-resistant GISTs potentiates the proapoptotic and anti-proliferative activities of the corresponding RTKi. Mechanistically, the FGF2-induced activation of the FGFR pathway turns on VEGFR signaling via the overproduction of VEGF-A, induces the interaction between FGFR1/2 and VEGFR1, and thereby renders cancer cells highly sensitive to the dual inhibition of the aforementioned RTKs. Thus, our data uncovers the novel mechanism of the cross-talk between the aforementioned RTKs in IM-resistant GISTs lacking secondary KIT mutations and suggests that the dual blockade of FGFR and VEGFR signaling might be an effective treatment strategy for patients with GIST-acquired IM resistance via KIT-independent mechanisms.

Common Symptoms and a Rare Diagnosis: A Case of Duodenal Gastrointestinal Stromal Tumor Presenting as Gastrointestinal Bleeding

Duodenal gastrointestinal stromal tumors (D-GISTs) are a rare subtype of GISTs, accounting for only 4% to 5% of all GIST cases. This case report details the presentation, diagnosis, and management of a 48-year-old female who presented with melena and anemia and was eventually diagnosed with a D-GIST. The tumor was identified through imaging studies, and histopathology performed after surgical resection revealed a submucosal neoplasm composed of spindle cells with extensive hemorrhage and necrosis. Given the tumor's rarity and its challenging presentation, which can mimic other conditions such as pancreatic masses, the case underscores the importance of considering D-GIST in differential diagnoses of duodenal or pancreatic lesions. Surgical resection remains the cornerstone of treatment, with adjuvant therapy considered in high-risk cases to prevent recurrence.

Molecular Profiling of KIT/PDGFRA-Mutant and Wild-Type Gastrointestinal Stromal Tumors (GISTs) with Clinicopathological Correlation: An 18-Year Experience at a Tertiary Center in Kuwait

In gastrointestinal stromal tumors (GISTs), identifying prototypical mutations in the KIT/PDGFRA oncogenes, or in rare alternate genes, is essential for prognostication and predicting response to tyrosine kinase inhibitors. Conversely, wild-type GISTs (WT-GIST), which lack known mutations, have limited treatment options. Data on the mutational landscape of GISTs and their impact on disease progression are very limited in Kuwait. Using a targeted next-generation sequencing panel, we investigated the spectrum and frequency of KIT, PDGFRA, and RAS-pathway-related mutations in 95 out of 200 GISTs diagnosed at Kuwait Cancer Center from 2005 to 2023 and assessed their correlation with clinicopathological parameters. Among the 200 tumors (median age 55 years; 15-91), 54% originated in the stomach, 33% in the small bowel, 7% in the colorectum, 1.5% in the peritoneum, and 4.5% had an unknown primary site. Of the 95 molecularly profiled cases, 88% had a mutation: KIT (61%), PDGFRA (25%), NF1 (2%), and one NTRK1 rearrangement. Ten WT-GISTs were identified (stomach = 6, small bowel = 2, and colorectum = 2). WT-GISTs tended to be smaller (median 4.0 cm; 0.5-8.0) (p = 0.018), with mitosis ≤5/5 mm2, and were of lower risk (p = 0.019). KIT mutations were an adverse indicator of disease progression (p = 0.049), while wild-type status did not significantly impact progression (p = 0.934). The genetic landscape in this cohort mirrors that of global studies, but regional collaborations are needed to correlate outcomes with genetic variants.

A population-based study on incidence trends of small intestine cancer in the United States from 2000 to 2020

BACKGROUND

Although rare, small intestine cancer is on the rise in the developed world. We aimed to investigate the incidence trends of small intestine cancer by sex, race/ethnicity, age, and histological subgroups in the United States (US) over 2000-2020. Also, we evaluated the COVID-19 impacts on the incidence trends of this cancer.

METHODS

Data were collected from the Surveillance, Epidemiology, and End Results 22 database. Both the average annual percent change (AAPC) and age-standardized incidence rates (ASIRs) were determined. The findings were expressed as counts and incidence rates adjusted for age per 100,000 people with 95% confidence intervals (CIs).

RESULTS

A total of 67,815 cases of small intestine cancer across all age groups were reported in the US between 2000 and 2019. Neuroendocrine carcinoma was the most often reported subtype (54.26%). The age group of 55 to 69 years (38.08%), men (53.10%), and Non-Hispanic Whites (69.07%) accounted for the majority of cases. Over 2000-2019, the ASIRs for small intestine cancer among men and women were 2.61 (95% CI: 2.59-2.64) and 1.92 (95% CI: 1.89-1.94) per 100,000, indicating a significant increase of 2.01% and 2.12%, respectively. Non-Hispanic Black men had the highest ASIR (4.25 per 100,000). Also, those aged 80-84 age group had the highest ASIR. During COVID-19, the ASIR of small intestine cancer decreased by 8.94% (5.06-12.81%).

CONCLUSIONS

Small intestine cancer incidence raised in all sexes and ethnicities. Following COVID-19, reported cases declined, possibly due to pandemic-related diagnostic challenges. The impact of underdiagnosis on patient survival needs further investigations.

A PDE3A-SLFN12 Molecular Glue Exhibits Significant Antitumor Activity in TKI-Resistant Gastrointestinal Stromal Tumors

PURPOSE

Gastrointestinal stromal tumor (GIST), the most common mesenchymal tumor with KIT or PDGFRA driver mutations, is typically treated with tyrosine kinase inhibitors (TKI). However, resistance to TKIs due to secondary mutations is a common challenge in advanced GISTs. In addition, there are currently no effective therapies for several other molecular subtypes, such as succinate dehydrogenase-deficient GISTs. Therefore, novel therapeutic strategies are needed.

EXPERIMENTAL DESIGN

To address this need, we tested the efficacy of a novel non-TKI compound, OPB-171775, using patient-derived xenograft models of GISTs. In parallel, we sought to elucidate the mechanism of action of the compound.

RESULTS

Our study revealed that OPB-171775 exhibited significant efficacy against GISTs regardless of their KIT mutation status by inducing complex formation between phosphodiesterase 3A (PDE3A) and Schlafen family member 12 (SLFN12), which are highly expressed in GISTs, leading to SLFN12 RNase-mediated cell death. Furthermore, we identified the activation of general control non-derepressible 2 and its downstream response as an effector pathway of SLFN12 in mediating anticancer activity and revealed potential pharmacodynamic markers.

CONCLUSIONS

These findings suggest that OPB-171775, with its significant efficacy, could potentially serve as a novel and effective treatment option for advanced GISTs, particularly those resistant to TKIs.

Therapeutic advances of targeting receptor tyrosine kinases in cancer

Receptor tyrosine kinases (RTKs), a category of transmembrane receptors, have gained significant clinical attention in oncology due to their central role in cancer pathogenesis. Genetic alterations, including mutations, amplifications, and overexpression of certain RTKs, are critical in creating environments conducive to tumor development. Following their discovery, extensive research has revealed how RTK dysregulation contributes to oncogenesis, with many cancer subtypes showing dependency on aberrant RTK signaling for their proliferation, survival and progression. These findings paved the way for targeted therapies that aim to inhibit crucial biological pathways in cancer. As a result, RTKs have emerged as primary targets in anticancer therapeutic development. Over the past two decades, this has led to the synthesis and clinical validation of numerous small molecule tyrosine kinase inhibitors (TKIs), now effectively utilized in treating various cancer types. In this manuscript we aim to provide a comprehensive understanding of the RTKs in the context of cancer. We explored the various alterations and overexpression of specific receptors across different malignancies, with special attention dedicated to the examination of current RTK inhibitors, highlighting their role as potential targeted therapies. By integrating the latest research findings and clinical evidence, we seek to elucidate the pivotal role of RTKs in cancer biology and the therapeutic efficacy of RTK inhibition with promising treatment outcomes.

Efficacy of Trametinib in Neurofibromatosis Type 1-Associated Gastrointestinal Stromal Tumors: A Case Report

Trametinib, an MEK inhibitor, may offer a new therapeutic option for patients with NF1-related GIST.

Comprehensive analysis of diagnosis and treatment in 99 cases of abdominal Schwannoma

PURPOSE

Schwannoma is a rare mesenchymal tumor. In this study, we analyzed clinicopathologically 99 schwannomas.This retrospective study delves into the clinical, pathological, and immunohistochemical dimensions of abdominal schwannomas.

RESULTS

A cohort of 99 cases, comprising 4 malignant and 95 benign schwannomas, was meticulously examined. Clinical analysis revealed a notable gender distribution (1:1.7, male to female) and an average age of 58.5 years. The majority of cases were asymptomatic. A cohort of 99 cases, comprising 4 malignant and 95 benign schwannomas, was meticulously examined. Clinical analysis revealed a notable gender distribution (1:1.7, male to female) and an average age of 58.5 years. The majority of cases were asymptomatic. Tumor sizes ranged from 0.5 to 30 cm, with distinct locations in the stomach for most benign cases and the abdomen/small intestine for malignancies. Initial misdiagnoses were frequent. Pathological evaluations revealed distinct features, including Antoni A and B patterns, spindle cells, and lymphatic sheath structures in benign schwannomas. Malignant cases exhibited atypical cells, ulcers, and invasive growth. Immunohistochemical markers, such as S100, SOX10, and vimentin, consistently demonstrated positivity by contributing to accurate diagnoses. Treatment outcomes indicated a poor prognosis in malignant cases, with overall survival ranging from 10 to 41 months. Conversely, benign cases displayed no recurrence or metastasis during follow-up, despite atypical behaviors.

CONCLUSION

This study underscores the rarity of abdominal schwannomas and underscores the need for a comprehensive diagnostic morphology and immunohistochemistry. SOX10 emerges as a crucial and specific marker for accurate diagnosis. Further research is imperative to refine diagnostic protocols and enhance our understanding of the clinical behavior of abdominal schwannomas.

Incidence and Survival Outcomes of Gastrointestinal Stromal Tumors

Importance

The incidence of gastrointestinal stromal tumors (GISTs) increased after the implementation of GIST-specific histology coding in 2001, but updated data on trends and survival are lacking.

Objective

To examine the evolving epidemiology of GISTs in major organ sites.

Design, Setting, and Participants

This descriptive, population-based cohort study used nationally representative data from the National Cancer Institute Surveillance, Epidemiology, and End Results (SEER) Program, including the SEER-22 and SEER-17 registries. Data were from evaluated patients aged 20 years or older with GISTs diagnosed between January 1, 2000, and December 31, 2019. Analyses were last updated on October 29, 2023.

Main Outcomes and Measures

Organ site-specific trends in age-standardized incidence rates and annual percent changes (APCs) in rates were estimated by race and ethnicity and, when possible, by sex, age, and primary indicator. Multivariable Cox proportional hazards regression models were used to examine racial and ethnic differences in overall and GIST-specific survival by site.

Results

The SEER-22 and SEER-17 datasets contained 23 001 and 12 109 case patients with GISTs, respectively. Patients in the SEER-22 registry had a mean (SD) age of 64 (13) years and 51.3% were men. With regard to race and ethnicity, 9.7% of patients were Asian or Pacific Islander, 12.3% were Hispanic, 19.6% were non-Hispanic Black, and 57.7% were non-Hispanic White. Overall incidence rates of GISTs in the SEER-22 cohort increased substantially over time for all organ sites but the colon (APCs: esophagus, 7.3% [95% CI, 4.4% to 10.2%]; gastric, 5.1% [95% CI, 4.2% to 6.1%]; small intestine, 2.7% [95% CI, 1.8% to 3.7%]; colon, -0.2% [95% CI, -1.3% to 0.9%]; and rectum, 1.9% [95% CI, 0.1% to 3.8%]). There were similar increasing trends by age groups (<50 vs ≥50 years), sex, race and ethnicity, and primary indicator for gastric and small intestine GISTs. Increases were mainly restricted to localized stage disease. Patients in the SEER-17 cohort had a mean (SD) age of 64 (14) years and 51.9% were men. With regard to race and ethnicity, 13.3% of patients were Asian or Pacific Islander, 11.6% were Hispanic, 17.8% were non-Hispanic Black, and 56.6% were non-Hispanic White. Non-Hispanic Black individuals had higher overall mortality for esophageal (adjusted hazard ratio [HR], 6.4 [95% CI, 2.0 to 20.3]) and gastric (adjusted HR, 1.4 [95% CI, 1.2 to 1.5]) GISTs compared with non-Hispanic White individuals. Asian or Pacific Islander individuals also had higher overall mortality for esophageal GISTs (adjusted HR, 5.6 [95% CI, 1.5 to 20.2]). Results were similar for GIST-specific survival.

Conclusions and Relevance

In this cohort study using SEER data, the incidence of GISTs in major organ sites increased in the last 2 decades among several population groups. These findings suggest that additional studies are warranted to identify risk factors, because histologic reclassification and higher availability of endoscopy and imaging do not fully explain these unfavorable incidence trends. Prevention efforts are needed to reduce the substantial survival disparities among racial and ethnic minoritized populations.

Intracystic gastrointestinal stromal tumor developed in the round ligament of the liver

A 44-year-old woman was referred to our hospital for the examination and treatment of a presumed gallbladder tumor. Both ultrasound and computed tomography showed an intracystic tumor but failed to point out the discontinuity between the cystic lesion and the gallbladder. Magnetic resonance imaging, however, could clearly depict the presumed intracystic tumor and the discontinuity between the gallbladder and the target lesion. Both contents of the gallbladder and the cystic lesion showed hypo and hyper intense patterns, though both with slightly different intensities, on T1- and T2-weighted images, respectively. Under the preoperative diagnosis of early gallbladder cancer despite these image findings, laparoscopic cholecystectomy was attempted to the patient. Laparoscopic observation, however, revealed that the target lesion was not continuous with the gallbladder and was located in the round ligament of the liver. Intraoperative findings led us to do cholecystectomy and resection of the adjacent cystic tumor. The intracystic tumor was 3 cm in size and had minute solid component inside the cyst wall. Pathological study of the presumed gallbladder cancer showed epithelioid cells and spindle cells growing in sheet like and storiform fashions, respectively. Cystic walls mainly consisted of hypo cellular fibrous components. Immunohistochemical staining of the tumor was positive for CD117 and negative both for desmin and S100, leading to the diagnosis of gastrointestinal stromal tumor. MIB-1 labelling index of the gastrointestinal stromal tumor was 8%. The patient recovered uneventfully and has been well without any recurrences for 3 months.

Different efficacy of tyrosine kinase inhibitors by KIT and PGFRA mutations identified in circulating tumor DNA for the treatment of refractory gastrointestinal stromal tumors

BACKGROUND

While advanced gastrointestinal stromal tumors (GISTs) are primarily treated with tyrosine kinase inhibitors (TKIs), acquired resistance from specific mutations in KIT or PDGFRA frequently occurs. We aimed to assess the utility of circulating tumor DNA (ctDNA) as a modality of therapeutic decision-making in advanced GIST.

METHODS

We conducted a pooled analysis of SCRUM-Japan studies for advanced GIST patients. We compared patient characteristics analyzed with tissue and blood samples, assessed gene alteration profiles, and evaluated prognostic implications from ctDNA status.

RESULTS

In 133 patients, tissue and blood samples were analyzed for 89 and 44 patients, respectively. ctDNA was detected in 72.7% of cases; no prior treatment or progressive disease was significantly associated with ctDNA-positivity. ctDNA-positive patients had significantly shorter progression-free survival compared with ctDNA-negative patients (hazard ratio = 3.92; P = 0.007). ctDNA genotyping revealed a complex landscape of gene alterations, characterized by multi-exonic mutations in KIT, compared with tissue-based analysis. Patients who received TKIs matched to the identified KIT mutation in ctDNA demonstrated significantly longer PFS than those with unmatched treatment (median, 8.23 vs. 2.43 months; P < 0.001).

CONCLUSIONS

ctDNA-based analysis facilitates assessment of disease status and genomic profiles, thus potentially assisting in identifying optimal therapeutic strategies for advanced GIST patients.

The immunotherapy in gastrointestinal stromal tumors

Using Tyrosine Kinase Inhibitors (TKIs) for gastrointestinal stromal tumors (GIST) has significantly reduced the risk of recurrence and prolonged survival. Immunotherapy has demonstrated efficacy in multiple solid tumors, but its effectiveness in GIST remains uncertain. Although early clinical studies indicate good tolerability of immunotherapy in patients, the efficacy is not as desired. Therefore, identifying the subset of GIST patients who benefit from immunotherapy and coordinating the relationship between immunotherapy and TKI treatment are crucial issues to be explored. In this review, we aims to provide a retrospective analysis of relevant literature and find that GIST patients exhibit a rich presence of tumor-infiltrating immune cells, which play critical roles in the immune surveillance and evasion processes of tumors. This review incorporates a selection of 48 articles published between 2002 and 2023, sourced from PubMed, EBSCO, and Google Scholar databases.

Molecular characteristics and immune microenvironment of gastrointestinal stromal tumours: targets for therapeutic strategies

Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal tumours, arising mainly from the interstitial cells of Cajal (ICCs) of the gastrointestinal tract. As radiotherapy and chemotherapy are generally ineffective for GISTs, the current primary treatment is surgical resection. However, surgical resection is not choice for most patients. Therefore, new therapeutic strategies are urgently needed. Targeted therapy, represented by tyrosine kinase inhibitors (TKIs), and immunotherapy, represented by immune checkpoint inhibitor therapies and chimeric antigen receptor T-cell immunotherapy (CAR-T), offer new therapeutic options in GISTs and have shown promising treatment responses. In this review, we summarize the molecular classification and immune microenvironment of GISTs and discuss the corresponding targeted therapy and immunotherapy options. This updated knowledge may provide more options for future therapeutic strategies and applications in GISTs.

A systematic review and meta-analysis of neoadjuvant imatinib use in locally advanced and metastatic gastrointestinal stromal tumors

BACKGROUND

Several doubts remain regarding the optimal use of neoadjuvant imatinib in gastrointestinal stromal tumors (GISTs), such as ideal treatment duration, patient selection, and long-term survival outcomes. This manuscript provides a comprehensive review on neoadjuvant imatinib treatment outcomes and facilitate evidence-based decision-making for the use of imatinib therapy in GISTs.

METHODS

Four databases (PubMed, EMBASE, Scopus, and Cochrane Library) were searched from inception to September 9, 2023. Meta-analyses of proportions were performed for the outcomes of R0 resection, disease responses, and 1-year, 3-year, and 5-year overall survival (OS) as well as 1-year, 3-year, and 5-year disease free survival (DFS). Sensitivity analyses in the form of leave-one-out analyses, meta-regression, and subgroup analyses were performed for outcomes with substantial statistical heterogeneity.

RESULTS

The search yielded 1254 articles, and 36 studies were included in our analysis. Meta-analysis of proportions revealed that 1-year, 3-year, and 5-year OS was 100%, 94%, and 88%, while 1-year, 3-year and 5-year DFS was 99%, 89%, and 79%, respectively. An R0 resection rate of 89% and a disease response rate of 67% was achieved after a mean duration of treatment of 8.41 ± 0.367 months. KIT exon 9 mutation was significantly associated with poorer 5-year DFS.

CONCLUSION

This study quantified key outcomes for neoadjuvant imatinib in locally advanced and metastatic or recurrent GIST. Patients with gastric and rectal tumous stand to benefit from neoadjuvant imatinib with an optimal treatment duration of 8 months. Furthermore, the potential utility of mutational analysis in guiding treatment with neoadjuvant imatinib was demonstrated.

A rare case of leiomyosarcoma with a pleomorphic component of the sigmoid colon

A 66-year-old man presented to our institution with a positive fecal occult blood test and lower abdominal pain. Although a tumor was found in the sigmoid colon, biopsy and imaging studies failed to enable the diagnosis of the cancer, and the patient underwent surgery for treatment and diagnosis. The tumor had two distinct areas with differing features shown both histopathologically and on imaging; it was thus diagnosed as a leiomyosarcoma of the sigmoid colon with a pleomorphic component. Here, we describe a rare case of leiomyosarcoma of the sigmoid colon with a pleomorphic component. There are no reports of leiomyosarcoma with pleomorphic components arising in the colon in the literature; thus, the recurrence and metastatic characteristics are unknown. Therefore, accumulating cases in the literature may provide valuable insights into diagnosing and treating these rare tumors.

Four and a half LIM domains 2 (FHL2) attenuates tumorigenesis of gastrointestinal stromal tumors (GISTs) by negatively regulating KIT signaling

Gastrointestinal stromal tumors (GISTs) are predominately induced by KIT mutants. In this study, we found that four and a half LIM domains 2 (FHL2) was highly expressed in GISTs and KIT signaling dramatically increased FHL2 transcription while FHL2 inhibited KIT transcription. In addition, our results showed that FHL2 associated with KIT and increased the ubiquitination of both wild-type KIT and primary KIT mutants in GISTs, leading to decreased expression and activation of KIT although primary KIT mutants were less inhibited by FHL2 than wild-type KIT. In the animal experiments, loss of FHL2 expression in mice carrying germline KIT/V558A mutation which can develop GISTs resulted in increased tumor growth, but increased sensitivity of GISTs to imatinib treatment which is used as the first-line targeted therapy of GISTs, suggesting that FHL2 plays a role in the response of GISTs to KIT inhibitor. Unlike wild-type KIT and primary KIT mutants, we further found that FHL2 didn't alter the expression and activation of drug-resistant secondary KIT mutants. Taken together, our results indicated that FHL2 acts as the negative feedback of KIT signaling in GISTs while primary KIT mutants are less sensitive and secondary KIT mutants are resistant to the inhibition of FHL2.

Gastrointestinal Stromal Tumors: A Retrospective Study at a Tertiary Care Center in Saudi Arabia in the Last Decade

INTRODUCTION

Gastrointestinal stromal tumors (GISTs) are a significant subset of mesenchymal tumors primarily found in the gastrointestinal tract, impacting diagnostic and therapeutic approaches. Understanding their epidemiology is crucial for improving patient care and advancing treatment strategies.

METHODOLOGY

Our study at a Saudi tertiary hospital analyzed 50 patients with GIST, focusing on demographics, tumor locations, and risk assessments. We examined predictors of tumor size, including mitosis frequency, and assessed the impact of anatomical location and risk on clinical outcomes using RStudio software (Posit, Boston, MA).

RESULTS

Among 50 patients with GIST, 36 (72.0%) were male with a median age of 60.5 years, and most tumors (33, 66.0%) were in the stomach. Risk assessments categorized tumors as follows: 20 (40.0%) low risk, 12 (24.0%) high risk, 7 (14.0%) moderate risk, 7 (14.0%) very low risk, and 4 (8.0%) no risk. Most tumors were low-grade (41, 82.0%) and nonmetastatic (47, 94.0%), predominantly spindle cell type (37, 74.0%). Tumor size varied significantly across risk categories: high-risk tumors averaged 10.3 cm versus 0.5 cm for no risk and 3.5 cm for very low risk (P < 0.001). Mitosis frequency differed significantly by risk category and tumor grade (P < 0.001). Tumor grade varied notably with risk categories and morphologic types, especially high-grade tumors in high-risk groups (8, 66.7%) and epithelioid tumors (2, 100%). Multivariable analysis identified predictors of tumor size: anatomical location (extra-GI, intra-abdominal; beta = 7.08, P = 0.011) and risk assessment (low risk, beta = 6.91, P = 0.001; moderate risk, beta = 11.2, P < 0.001; high risk, beta = 8.93, P < 0.001). Liver metastasis did not differ significantly across gender, anatomical location, risk assessment, or tumor grade.

CONCLUSIONS

In Saudi Arabia, GISTs predominantly affect males and are primarily located in the stomach. Our findings highlight significant variations in tumor size and grade based on risk assessments and anatomical location. Most GISTs were low-grade, nonmetastatic, and spindle cell type, emphasizing the need for enhanced research to improve diagnostics, tailor treatments, and optimize outcomes in the region.

Recommendations for the use of next-generation sequencing (NGS) for patients with advanced cancer in 2024: a report from the ESMO Precision Medicine Working Group

BACKGROUND

Advancements in the field of precision medicine have prompted the European Society for Medical Oncology (ESMO) Precision Medicine Working Group to update the recommendations for the use of tumour next-generation sequencing (NGS) for patients with advanced cancers in routine practice.

METHODS

The group discussed the clinical impact of tumour NGS in guiding treatment decision using the ESMO Scale for Clinical Actionability of molecular Targets (ESCAT) considering cost-effectiveness and accessibility.

RESULTS

As for 2020 recommendations, ESMO recommends running tumour NGS in advanced non-squamous non-small-cell lung cancer, prostate cancer, colorectal cancer, cholangiocarcinoma, and ovarian cancer. Moreover, it is recommended to carry out tumour NGS in clinical research centres and under specific circumstances discussed with patients. In this updated report, the consensus within the group has led to an expansion of the recommendations to encompass patients with advanced breast cancer and rare tumours such as gastrointestinal stromal tumours, sarcoma, thyroid cancer, and cancer of unknown primary. Finally, ESMO recommends carrying out tumour NGS to detect tumour-agnostic alterations in patients with metastatic cancers where access to matched therapies is available.

CONCLUSION

Tumour NGS is increasingly expanding its scope and application within oncology with the aim of enhancing the efficacy of precision medicine for patients with cancer.

Neoadjuvant Imatinib in Gastrointestinal Stromal Tumors (GIST): The First Analysis of a Mexican Population

Introduction Gastrointestinal stromal tumors (GISTs) are neoplasms originating from the interstitial cells of Cajal, pacemaker cells responsible for intestinal motility. Patients with locally advanced GISTs and those with borderline resections due to the proximity of vital anatomical structures, which could result in unacceptable post-surgical morbidity, require special therapeutic consideration. Imatinib, a tyrosine kinase inhibitor, has demonstrated significant success in the non-surgical management of metastatic GIST, and its favorable impact on overall survival in the adjuvant setting makes it logical to speculate on the benefit it could provide as a neoadjuvant medication in patients with locally advanced disease. Methods Patients aged 18-90 years with a diagnosis of GIST confirmed by immunohistochemistry (CD117 positivity) who were treated at the Oncology Hospital of Centro Médico Nacional Siglo XXI in Mexico City from January 2012 to December 2016 were included in the study. It is a retrospective study with a duration of four years. Clinical data were collected from the medical records, which included sex, age, tumor location, initial resectability, reason for unresectability, initial tumor size, and mitotic rate. In the case of unresectable disease, patients who were evaluated by medical oncology and who had received treatment with 400 mg of imatinib daily were evaluated. Results A total of 312 patients diagnosed with GIST were analyzed. One hundred thirty-one were men (42%) with a mean age of 57 years, and 181 were women (58%) with a mean age of 59 years. The most frequent anatomical location was the stomach (n=185, 59.2%). At the time of diagnosis, 210 patients (67.3%) presented with resectable disease, while n=102 patients (32.7%) had unresectable disease. A total of 102 patients with unresectable disease received therapy with 400 mg of imatinib per day. Sixteen patients (15.7%) presented a reduction in tumor dimensions and underwent surgery. Conclusion The study highlights the importance of complete surgical resection and the potential benefit of neoadjuvant imatinib therapy in converting unresectable to resectable disease. The results suggest that imatinib can be effective in converting unresectable GISTs to resectable ones, allowing for a complete resection to be performed and obtaining an R0 resection in 93.7% of these cases.

Entry of ZSWIM4 to the nucleus is crucial for its inhibition of KIT and BMAL1 in gastrointestinal stromal tumors

BACKGROUND

Zinc finger SWIM-type containing 4 (ZSWIM4) is a zinc finger protein with its function largely uncharacterized. In this study, we aimed to investigate the role of ZSWIM4 in gastrointestinal stromal tumors (GISTs).

RESULTS

We found that ZSWIM4 expression is inhibited by the predominantly mutated protein KIT in GISTs, while conversely, ZSWIM4 inhibits KIT expression and downstream signaling. Consistent with the observation, ZSWIM4 inhibited GIST cell survival and proliferation in vitro. RNA sequencing of GISTs from KITV558A/WT mice and KITV558A/WT/ZSWIM4-/- mice showed that loss of ZSWIM4 expression increases the expression of circadian clock pathway member BMAL1 which contributes to GIST cell survival and proliferation. In addition, we found that KIT signaling increases the distribution of ZSWIM4 in the nucleus of GIST cells, and which is important for its inhibition of KIT and BMAL1. In agreement with the results in vitro, the in vivo studies showed that ZSWIM4 deficiency increases the tumorigenesis of GISTs in KITV558A/WT mice.

CONCLUSIONS

Taken together, our results revealed that the entry of ZSWIM4 to the nucleus is important for its inhibition of KIT and BMAL1, ultimately attenuating GIST tumorigenesis. The results provide a novel insight in the understanding of signal transduction in GISTs and lay strong theoretical basis for the advancement of GIST treatment.