C-kit Mutation Research Articles

Unraveling Gastric and Small Intestine Gastrointestinal Stromal Tumors: A Review of Our Current Knowledge

Background: Gastrointestinal Stromal Tumors (GISTs) are characterized as round, well–defined mass lesions in the submucosal layer of the gastrointestinal (GI) tract. GISTs often present histological diversity and mutations in c-KIT and PDGFRA genes. Symptoms usually appear as abdominal pain, often accompanied by gastrointestinal bleeding or abdominal mass. The prognosis relies on tumor size, mitotic index, and different mutations, such as KIT mutations. There are a variety of diagnostic measures in the case of GISTs. However, it is important to note that ultrasound is the most common and reliable method for diagnosing gastric GISTs. The treatment methods followed vary from preoperative systemic therapy to surgical interventions. Depending on the type of GIST, professionals decide upon the best treatment plan for the patient. Objective: This review aims to inform the scientific community about the intricacies of gastric and small intestine GISTs to enhance understanding and improve patient management, with a particular focus on the importance of understanding and interpreting the unique microscopic histopathological findings of GISTs.

Artificial intelligence can be trained to predict c-KIT-11 mutational status of canine mast cell tumors from hematoxylin and eosin-stained histological slides.

Numerous prognostic factors are currently assessed histologically and immunohistochemically in canine mast cell tumors (MCTs) to evaluate clinical behavior. In addition, polymerase chain reaction (PCR) is often performed to detect internal tandem duplication (ITD) mutations in exon 11 of the c-KIT gene (c-KIT-11-ITD) to predict the therapeutic response to tyrosine kinase inhibitors. This project aimed at training deep learning models (DLMs) to identify MCTs with c-KIT-11-ITD solely based on morphology. Hematoxylin and eosin (HE) stained slides of 368 cutaneous, subcutaneous, and mucocutaneous MCTs (195 with ITD and 173 without) were stained consecutively in 2 different laboratories and scanned with 3 different slide scanners. This resulted in 6 data sets (stain-scanner variations representing diagnostic institutions) of whole-slide images. DLMs were trained with single and mixed data sets and their performances were assessed under stain-scanner variations (domain shifts). The DLM correctly classified HE slides according to their c-KIT-11-ITD status in up to 87% of cases with a 0.90 sensitivity and a 0.83 specificity. A relevant performance drop could be observed when the stain-scanner combination of training and test data set differed. Multi-institutional data sets improved the average accuracy but did not reach the maximum accuracy of algorithms trained and tested on the same stain-scanner variant (ie, intra-institutional). In summary, DLM-based morphological examination can predict c-KIT-11-ITD with high accuracy in canine MCTs in HE slides. However, staining protocol and scanner type influence accuracy. Larger data sets of scans from different laboratories and scanners may lead to more robust DLMs to identify c-KIT mutations in HE slides.

Progression of Mast Cell Activation Syndrome to Systemic Mastocytosis

Abstract Introduction/Objective Mast cell activation syndrome (MCAS) is characterized by the abnormal release of mast cell mediators, leading to symptoms such as flushing, abdominal pain, and allergic reactions. In some cases, MCAS progresses to systemic mastocytosis (SM), a mast cell disorder marked by organ infiltration and dysfunction. However, predictors of MCAS progression to SM remain poorly understood, and long-term prognosis data are limited. Methods/Case Report We conducted a retrospective study of patients diagnosed with MCAS at Penn Medicine from January 1, 2019, through December 30, 2021. The primary endpoint was progression to SM, defined by World Health Organization criteria, with a secondary endpoint set for September 24, 2023. Results (if a Case Study enter NA) We identified 47 patients with MCAS (Table 1). Of these, 11 patients (23.4%) progressed to SM. Notably, all five patients with c-KIT mutations progressed to SM (100%, 5/5), while six out of 22 patients without c-KIT mutations also progressed (27.2%). Additionally, baseline serum tryptase levels were identified as a significant predictor of progression at two years. Conclusion The relative risk of progression varied depending on the subtype of MCAS, with higher rates observed in those with KIT D816V presence. Compared to the incidence of SM in the general population, our findings suggest a higher risk of progression from MCAS to SM, even without a c-KIT mutation. Identification of prognostic factors, such as specific genetic mutations and baseline serum tryptase levels, may aid in risk stratification and early intervention strategies for individuals with MCAS. HaT mutation testing should be considered in future studies on this topic. Our findings have important implications for the clinical management and understanding of MCAS progression to SM. Additionally, our data imply the importance of recognizing MCAS in the early phase and proper monitoring, considering the low rate of MCAS diagnosis. Patients with MCAS may need annual monitoring, including serum tryptase levels, to detect progression to SM and related complications. Early detection and intervention may improve outcomes and quality of life for individuals with MCAS.

Survival of advanced/recurrent gastrointestinal stromal tumors treated with tyrosine kinase inhibitors in Taiwan: a nationwide registry study

BackgroundMost gastrointestinal stromal tumors (GISTs) harbor c-KIT or PDGFRA mutations. Administration of tyrosine kinase inhibitors (TKIs) has significantly improved the survival of patients with GISTs. We aimed to evaluate the clinical outcome of advanced or recurrent GIST patients in Taiwan.MethodsPatients diagnosed between 2010 and 2020 were enrolled. The collected data included baseline characteristics, treatment pattern, treatment outcome, genetic aberrations and survival status. Progression-free survival (PFS) and overall survival (OS) were analyzed and plotted with the Kaplan–Meier method. Cox regression analysis was used to analyze the prognostic factors of survival.ResultsA total of 224 patients with advanced or recurrent GISTs treated with TKIs were enrolled. All patients received imatinib treatment. Ninety-three and 42 patients received sunitinib and regorafenib treatment, respectively. The 48-month PFS and OS rates for patients treated with imatinib were 50.5% and 79.5%, respectively. c-KIT exon 9 and PDGFRA mutations were prognostic factors for a poor PFS and PDGFRA mutation was a prognostic factor for a poor OS in patients treated with imatinib in multivariate Cox regression analysis. The median PFS of patients who received sunitinib treatment was 12.76 months (95% confidence interval (CI), 11.01–14.52). Patients with c-KIT exon 9 mutations had a longer PFS than those with other genetic aberrations. The median PFS of patients treated with regorafenib was 7.14 months (95% CI, 3.39–10.89).ConclusionsWe present real-world clinical outcomes for advanced GIST patients treated with TKIs and identify mutational status as an independent prognostic factor for patient survival.

Homoharringtonine may help improve the outcomes of venetoclax and azacitidine in AML1-ETO positive acute myeloid leukemia

PurposeT(8;21)(q22;q22.1)/AML1-ETO positive acute myeloid leukemia (AE-AML) is sensitive to conventional chemotherapy with a favorable prognosis. However, recent small case reports suggest the limited effectiveness of venetoclax (VEN) and hypomethylating agents (HMA) in treating AE-AML. The aim of this retrospective study was to evaluate the effectiveness of VEN plus AZA (VA) in AE-AML and explore whether adding homoharringtonine (HHT) to VA (VAH) could improve the response.MethodsPatients who received VEN plus AZA and HHT (VAH) or VEN plus AZA (VA) regimens were included in this retrospective study. The endpoints of this study were to evaluate the rate of composite complete remission (CRc), measurable residual disease (MRD), event-free survival (EFS), overall survival (OS), and relapse between VAH and VA groups.ResultsA total of 32 AE-AML patients who underwent VA or VAH treatments (newly diagnosed with VA, ND-VA, n = 8; relapsed/refractory with VA, R/R-VA, n = 10; relapsed/refractory with VAH, R/R-VAH, n = 14) were included. The CR (complete remission) /CRi (CR with incomplete count recovery) rate of ND-VA, R/R-VA and R/R-VAH were 25%, 10%, and 64.3%, respectively. Measurable residual disease (MRD) negative was observed in 66.7% of R/R-VAH and none of VA-R/R patients. Co-occurring methylation mutations are associated with poor outcomes with VA but exhibit a more favorable response with VAH treatment. Additionally, patients with c-kit mutation presented inferior outcomes with both VEN-based regimens. All regimens were tolerated well by all patients.ConclusionOur data confirmed the poor response of VA in AE-AML, whether used as frontline or salvage therapy. Adding HHT to VA may improve outcomes and enhance the efficacy of VEN in this population.

Gastro Intestinal Stromal Tumor: Cases Series Report

Gastrointestinal stromal tumors (GISTs) are rare mesenchymal tumors of the alimentary tract. Now a day GISTs represents 0.1-3% of all gastrointestinal malignancies, making it a diagnostic challenge. Lesions are frequently located in stomach and proximal small intestine but rarely elsewhere in the abdomen. They are believed to result from mutations of protooncogenes c-Kit or platelet-derived growth factor receptor alpha polypeptide, this increase tyrosine kinase receptor activity, leading to uncontrolled proliferation of stem cells that differentiate into cells of Cajal. They can occur at any age but predominantly in middle-aged people and in elderly. We reported the cases presented to our hospital with progressively distension of the abdomen, finding in diagnostic image suggested GIST without evidence of metastasis disease, total excision was done, Cytologic and immunohistochemistry analysis confirm diagnosis of GISTs.

Two cases of systemic mastocytosis with RUNX1-RUNX1T1 positive acute myeloid leukemia treated with sequential avapritinib after allogeneic hematopoietic stem cell transplantation and literature review

Systemic mastocytosis (SM) with RUNX1-RUNX1T1 positive acute myeloid leukemia (AML) is a rare myeloid tumor with no standard treatment. Two cases of SM patients with RUNX1-RUNX1T1 positive AML treated with sequential avapritinib after allogeneic hematopoietic stem cell transplantation (allo-HSCT) were reported in Henan Cancer Hospital. Mast cell in bone marrow disappeared, C-KIT mutation and RUNX1-RUNX1T1 fusion gene remained negative. Allo-HSCT sequential avapritinib is an effective treatment for SM patients with RUNX1-RUNX1T1 positive AML.

Abstract 3142: NN3201, a novel c-Kit targeting ADC, exhibits robust preclinical anti-tumor efficacy in SCLC and GIST models

Abstract c-Kit (CD117) is a type III receptor tyrosine kinase (RTK), which is known to be activated upon binding to its cognate ligand stem cell factor (SCF) to induce critical signaling pathways involved in cell proliferation, survival, and differentiation. Indicative of poor prognosis, overexpression and activating mutations of c-Kit have been implicated in a variety of human cancers including small cell lung cancer (SCLC), gastrointestinal stromal tumors (GIST), and acute myelogenous leukemia (AML). While imatinib, a small molecule c-Kit inhibitor, has been a beneficial treatment for GIST, resistance eventually develops to the drug, moreover, shows limited efficacy in c-Kit overexpressing tumors such as SCLC. Herein, we developed NN3201, a novel c-Kit targeting antibody-drug conjugate (ADC), comprised of fully human 2G4 antibody with a picomolar binding affinity to c-Kit and cytotoxic monomethyl auristatin E (MMAE) as the payload. NN3201 displayed potent in vitro cytotoxicity in various wild-type and mutant c-Kit positive SCLC and GIST cell lines with IC50 in the nanomolar range. In addition, NN3201 was rapidly internalized and inhibited c-Kit-mediated signaling., NN3201 treatment resulted in the increased proportions of the sub G1 and G2/M in the c-Kit positive cancer cell lines, indicating that release of MMAE induced cell cycle arrest. Moreover, bystander effect was confirmed by co-culturing c-Kit high and negative cell lines. Most importantly, in mouse xenograft models, NN3201 showed a remarkable tumor growth inhibition of several wild type, mutant c-Kit positive, and imatinib resistant SCLC and GIST cell lines. Enhanced anti-tumor activity and delayed tumor growth were observed in an SOC-treated (etoposide and carboplatin) SCLC xenograft model, by NN3201 in comparison to second line SOC (topotecan or irinotecan). In the GLP study, repeated intravenous administration of NN3201 was well tolerated at all doses (0.5, 1, 2 mg/kg Q3Wx3) without unscheduled death. Dose-dependent, yet transient, cytotoxicity of NN3201 was observed in the bone marrow. We confirmed HNSTD (Highest Non-Severely Toxic Dose) of NN3201 to be 2 mg/kg through exploratory and GLP repeat dose toxicity studies as no serious irreversible toxicity was observed. Accumulating data suggest that NN3201 is a promising therapeutic alternative for the treatment of SCLC and GIST regardless of wild-type or activating mutations in c-Kit. Citation Format: Chansik Kim, Jin Gu Cho, TaeMin Wi, Jiwoo Moon, Han-Jik Ko, Jina Lee, Jin Woo Park, Yeonjy Lee, Sanghee Kim, Jin-Ock Kim, Jaeyoung Song, Sun-Hwa Lee, Sang Gyu Park. NN3201, a novel c-Kit targeting ADC, exhibits robust preclinical anti-tumor efficacy in SCLC and GIST models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3142.

Stem cell factor and cKIT modulate endothelial glycolysis in hypoxia.

In hypoxia, endothelial cells (ECs) proliferate, migrate, and form new vasculature in a process called angiogenesis. Recent studies have suggested that ECs rely on glycolysis to meet metabolic needs for angiogenesis in ischaemic tissues, and several studies have investigated the molecular mechanisms integrating angiogenesis and endothelial metabolism. Here, we investigated the role of stem cell factor (SCF) and its receptor, cKIT, in regulating endothelial glycolysis during hypoxia-driven angiogenesis. SCF and cKIT signalling increased the glucose uptake, lactate production, and glycolysis in human ECs under hypoxia. Mechanistically, SCF and cKIT signalling enhanced the expression of genes encoding glucose transporter 1 (GLUT1) and glycolytic enzymes via Akt- and ERK1/2-dependent increased translation of hypoxia inducible factor 1A (HIF1A). In hypoxic conditions, reduction of glycolysis and HIF-1α expression using chemical inhibitors significantly reduced the SCF-induced in vitro angiogenesis in human ECs. Compared with normal mice, mice with oxygen-induced retinopathy (OIR), characterized by ischaemia-driven pathological retinal neovascularization, displayed increased levels of SCF, cKIT, HIF-1α, GLUT1, and glycolytic enzymes in the retina. Moreover, cKIT-positive neovessels in the retina of mice with OIR showed elevated expression of GLUT1 and glycolytic enzymes. Further, blocking SCF and cKIT signalling using anti-SCF neutralizing IgG and cKIT mutant mice significantly reduced the expression of HIF-1α, GLUT1, and glycolytic enzymes and decreased the pathological neovascularization in the retina of mice with OIR. We demonstrated that SCF and cKIT signalling regulate angiogenesis by controlling endothelial glycolysis in hypoxia and elucidated the SCF/cKIT/HIF-1α axis as a novel metabolic regulation pathway during hypoxia-driven pathological angiogenesis.

The Effect of Non-Overlapping Somatic Mutations in BRAF, NRAS, NF1, or CKIT on the Incidence and Outcome of Brain Metastases during Immune Checkpoint Inhibitor Therapy of Metastatic Melanoma

The Effect of Non-Overlapping Somatic Mutations in BRAF, NRAS, NF1, or CKIT on the Incidence and Outcome of Brain Metastases during Immune Checkpoint Inhibitor Therapy of Metastatic Melanoma

Mucosal Melanoma Clinical Management and Prognostic Implications: A Retrospective Cohort Study.

Mucosal melanoma (MM) is an uncommon melanoma subtype affecting mucosal surfaces of the head and neck, anorectal region, and vulvovaginal area. We aimed to present our experience at a tertiary-level hospital regarding MM diagnosis, management, monitoring of progression, mutations, and outcome predictors. We performed a registry-based cohort study including MM cases diagnosed from 2012 to 2022 and retrospectively characterized somatic mutations on BRAF, NRAS and c-KIT. We employed Kaplan-Meier curves, log-rank tests, and Cox regression analysis to explore prognostic factors and survival outcomes in a cohort of 35 patients, mainly women (63%) with a median age of 70 years. Predominantly, MM occurred in the vulvovaginal region (48.6%). At diagnosis, 28.6% had lymph node involvement, and 31.4% also had distant metastasis. Mutations in BRAF and c-KIT were identified in 3/35 (9%) and 2/6 patients (33%), respectively. Surgery was performed in 71.4% of patients, and most received systemic treatment (65.7%). Lower disease stage, thinner Breslow depth, and surgical resection were associated with improved overall survival. Notably, age, sex, radiotherapy, and BRAF mutant status did not affect survival. Standard management typically involves immunotherapy. Cases with BRAF or c-KIT mutations may be considered for targeted therapies. Unfortunately, MM prognosis remains unfavorable, with a less than 50% survival rate at 2 years.

Mast cells, mediators, and symptomatic activation

<abstract> <p>Mast cells (MC) are central effectors of allergic disease and distinct subsets with varying amounts of tryptase, chymase, and carboxypeptidase A3, and cathepsin G is distributed throughout the body. Their involvement in a diverse range of non-allergic illnesses mediated by a complex range of preformed and newly synthesized mediators is now increasingly recognized. The latter especially include conditions under the umbrella term of mast cell activation syndrome. In allergic disease, much has been written about the mechanisms by which the early and rapidly acting mediators produce both localized and systemic allergic symptoms. The role of chymase is presently underappreciated but there is increased awareness that MCs contain significant amounts of preformed TNF alpha and synthesize and releases a wide range of inflammatory cytokines such as interleukins (IL) 1β, IL6, IL31, and IL33. These can aggravate itching and perpetuate inflammation and likely contribute to the late constitutional symptoms seen in allergic reactions. Importantly, their involvement helps to clarify the role of MCs in stress and non-parasitic infections. Presently, unexplained is the increasing incidence of significant acute allergic reactions within a relatively short time frame. In this context, there is increasing interest in the environmental, menstrual, endocrine, circadian, and psychological factors that influence MC activation as well as the endocrine pathways involving the renin angiotensin system that oppose hypotension. In non-allergic diseases with normal numbers of MCs, reduced thresholds for activation may be produced by various combinations of life and dietary factors. Diagnosing these conditions is difficult but may be helped by urinary analysis of prostaglandin metabolites. The investigation and management of mastocytosis with and without mutations of c-kit is also relevant to allergic disease and the new medications used may also be helpful in idiopathic anaphylaxis. This knowledge may open a new chapter in human diseases and mast cell regulation.</p> </abstract>

C-Kit and Flt3 mutation status in acute myeloid leukaemia with cytogenetic correlation and prognosis: A series of 75 cases

Recent WHO classification (5 edition) has included Acute Myeloid Leukaemia (AML) with mutations in NPM1, CEBPA as separate entities along with AML with cytogenetic abnormalities in AML with recurrent genetic abnormalities. Even though C-kit and FLT3 mutations in AML have no diagnostic importance, prognostic significance in different subtypes of AML for the presence of these mutations are not the same.To assess the correlation between French American British (FAB) AML classification, specific cytogenetic abnormalities with C-kit, and FLT3 mutation in AML and to evaluate the prognosis and survival of AML patients with respect to cytogenetic abnormalities and C-kit and FLT3 mutation status. Retrospectively all AML cases in which C-kit and FLT3 mutation status was assessed were retrieved; C-kit D816V mutation status had been assessed by Real time PCR; For FLT3 mutation, both Internal tandem duplication (ITD) and D835V mutation status had been assessed using PCR and gel electrophoresis; The data regarding morphological with immunophenotypic diagnosis, conventional karyotyping, FISH for translocation 8;21 (t (8;21)) and inversion16 / translocation16;16 (t (16;16) were also retrieved in all these cases along with follow-up from hospital records. Total 75 cases were included; Male/ Female ratio was 1.21:1 (41/34); Median age was 31 (Range: 2 - 64); 18 cases had translocation 8;21 (t (8;21)); 3 cases showed inversion16 / translocation16;16 (t (16;16); Out of the 18 cases which showed t (8;21), 10 cases had associated loss of sex chromosome. Eight cases had C-kit D816V mutation; three of which had t (8;21) while two had inversion 16. 12 cases had FLT3 mutations among which nine were ITD while three had D835V mutation. On karyotyping, one of these cases showed hyperdiploidy while the majority had normal karyotype. A single case had both C-kit D816V mutation and FLT3 D835V mutation with inversion 16 on karyotyping; Most common type of AML in both cases with FLT3 mutation and C-kit mutation was AML-M2 (FAB); Commonest karyotyping abnormality for cases with C-kit mutation was t(8;21); while for FLT3 mutation, the majority had normal karyotype; The single case which had both C-kit D816V mutation and FLT3 D835V mutation was alive event-free at three-year follow-up. Both FLT3 ITD and TKD mutations had a worse prognosis in our study. However, AML cases with C-kit mutation had a similar prognosis comparable to C kit negative cases. A large-scale study is required to elucidate the significance of this.

A Case of Recurrent Gastrointestinal Stromal Tumor with Chondroid Differentiation

Abstract Introduction/Objective Gastrointestinal stromal tumors (GIST) comprise 0.1% to 3% of gastrointestinal neoplasms but are the most common mesenchymal tumors in the gastrointestinal tract. They originate from the interstitial cells of Cajal and most frequently arise in the stomach. However, chondroid differentiation of GIST is extremely rare with less than ten cases reported in the literature. We present a case of a 58-year-old female with recurrent GIST post-imatinib therapy. Methods/Case Report The patient was originally diagnosed with GIST seven years prior when she visited the Emergency Department after a syncopal episode and was incidentally found to have a 11 x 8.5 x 7 cm gastric mass based on abdominal CT scan. She underwent biopsy that showed spindle cell lesion staining positively for DOG1 and CD117 and negatively for desmin, consistent with GIST. She subsequently underwent partial gastrectomy with pathology showing high grade spindle cell type GIST with focal bizarre epithelioid cells and necrosis. Molecular testing identified the tumor to have a c-KIT mutation. Based on large tumor size and risk of recurrence, she was treated with imatinib for three years. Two years after completion of imatinib therapy, her surveillance imaging showed a mass compatible with recurrence measuring 11.8 x 11.7 x 6.7 cm. Additionally, imaging identified a mass in her mid abdomen that was biopsied and showed metastatic GIST supported by immunophenotype. The patient undewent a second partial gastrectomy and the mass on gross examination showed a heterogeneous cut surface displaying some solid and necrotic areas that appears to have invaded adjacent adipose tissue. Histomorphological features showed a spindle component with necrosis and a focus of chondroid differentiation. Tumor cells were immunopositive for DOG1 and CD117. The chondroid component did not stain for either marker. Results (if a Case Study enter NA) NA Conclusion There have been few reported cases of GIST with chondroid differentiation. Moreover, a previous study found three of 35 patients who showed phenotypic alteration post-imatinib therapy with changes ranging from tubulopapillary to epithelioid morphology. However, there has been no case with chondroid differentiation after imatinib therapy reported. This case illustrates the variable response of GIST to imatinib and its possible transformation because of the therapy. To better understand the prognosis of GIST with chondroid differentiation, more cases should be identified, reported, and monitored closely.

Successful Management of D816V Mutated c-KIT Systemic Mastocytosis with Chronic Imatinib: A Case Report

First characterized in France in 1936, systemic mastocytosis (SM) is a rare disorder by an excessive proliferation and accumulation of abnormal mast cells in extracutaneous tissues (Nettleship et al., 1869). The release of large quantities of vasoactive mediators by these cells results in allergic- and anaphylactic-type reactions in one or more organ systems. Given the similarity of symptoms between allergic reactions and SM and the rarity of the condition, SM is often missed and misdiagnosed (Schwaab et al., 2020). Once considered a subtype of myeloproliferative neoplasms, mastocytosis was reclassified in the 2016 revision to the World Health Organization (WHO) due to advances in understanding of the disorder (Arber, et al., 2016). Presented below is a case of a severe systemic mastocytosis with an initially positive D816V mutated c-kit successfully managed with long-term imatinib use alongside intermittent bone marrow biopsies (BMB) to monitor what is now an indolent systemic mastocytosis. 69 year-old female with a past medical history of paroxysmal atrial fibrilation, hashimoto's thyroiditis, metabolic syndrome, and gastro-esophageal reflux (GERD) presents to clinic for routine management of what was previously severe systemic mastocytosis (SSM) and now is indolent systemic mastocytosis with the help of imatinib. To help control her ISM her medications include a daily histamine-1 blocker (ranitidine), a daily histamine-2 blocker (diphenhydramine), and a twice-daily histamine-1 antagonist (cetirizine). Originally evaluated in 2005 with a bone marrow biopsy (BMB) and found to have a Asp816Val (D816V) c-kit mutation, she was placed on imatinib with significant clinical improvement. This seemed to support that the D816V mutation may cause constitutional activation of the c-kit transmembrane protein and thus sensitivity to imatinib therapy. This despite the FDA labeling for imatinib as only to be used in SM patients without the common D816V mutation or for whom the mutational status is unknown (Reference ID: 4957210, 2001). Interestingly, after being placed on imatinib her repeat bone marrow biopsies in 2011 and 2015 indicated that the D816V mutation was no longer present in her CD117 positive mast cells but continued to benefit from imatinib therapy. This finding is suggestive of two unique mast cell populations as imatinib continued to help maintain a low tryptase level and decrease the severity of reactions. When reactions did occur, she treated them at one point with a cocktail of an histamine-2 blocker (ranitidine), histamine-1 blocker (diphenhydramine), and a mast cell stabilizer (cromolyn) and without requiring the use of epinephrine. As a part of her longitudinal observation, she received an additional BMB in 2022 that revealed a minimal residual monocytosis that persisted with less than 10% nucleated cells, an age-appropriate trilinear hematopoiesis, decreased iron stores without ringed sideroblast formation. Flow cytometry was indicative of a typical female karyotype with the population of aberrant mast cells that is consistent with the diagnosis of ISM. Importantly, no abnormalities were detected in the FLT3, IDH1, IDH2, NPM1 genes which, if abnormal, could obfuscate the apparent efficacy of imatinib treatment in the management of SM. Given the dearth of mastocytosis in the BMB and the absence of ongoing end-organ damage, the patient meets the definition of ISM. After the most recent BMB the patient altered her daily regimen due to gastric upset and found she could take of her histamine-1 blocker (diphenhydramine) once daily along with a twice daily regimen of her imatinib (split into two smaller daily doses), histamine-1 antagonist (cetirizine), her histamine-2 antagonist (famotidine), and citalopram (selective serotonin reuptake inhibitor or SSRI) with improved symptomatic control to this day. This case serves to illustrate the diagnostic and therapeutic challenges associated with SM, as well as the potential therapeutic use of imatinib in patients with D816V outside of its original FDA indication. Further characterization of the effect of imatinib on D816V mutated SM may warrant the consideration of expanding the FDA indications for imatinib as its role and efficacy outside of solely D816V negative c-kit MS.

Molecular Characterisation and Outcomes of 363 Adolescent and Young Adults with AML in Saudi Arabia Risk Stratified By PCR and NGS-Based Testing

Introduction Acute Myeloid Leukaemia (AML) is characterised by cytogenetic (CGN) abnormalities and or mutations in one or more of a number of genes that allow risk stratification and guide treatment. The mutational landscape of patients from Saudi Arabia, which has a young population, has not been well characterised. One study indicates a higher rate of core binding factor and monosomies. Mutational analysis by Next generation sequencing (NGS) has not had widespread utilisation hampering the risk stratification of AML in the country. The more recent introduction of NGS panels has allowed more risk stratification. Here we analysed patients and characterised the CGN and molecular abnormalities. Methods Data were collected from 363 patients, and their cytogenetic and molecular results were reviewed. Patients were divided into 2 cohorts: Cohort A only had PCR-based testing diagnosed or treated at King Faisal Specialist Hospital and research centre - Riyadh. PCR testing included mutation analysis for FLT3, NPM1, CEBPA, c-KIT, IDH1, IDH2, WT1, DNMT3A, and JAK2; quantitative PCR for RUNX1-ETO in a subset of patients. Cohort B had PCR-based mutation testing in addition to the Next-Generation Sequencing (NGS) myeloid panel, which was Illumina-based or Ion Torrent. The panel comprises 23 hotspot genes, 17 entire genes, 29 fusion drivers, and five expression genes associated with haematological malignancies. We risk-stratified patients according to the most recent testing method available. Cohort A and Cohort B were risk-stratified, according to ELN risk classification 2017. Survival analysis for these patients was conducted. Results The median age for all patients was 39 years (13-89). PCR testing included mutation analysis for FLT3 (93.4%), NPM1 (90.4%), CEBPA (69.7%), c -KIT (54.3%), IDH1 (57%), IDH2 (57.9%), WT1 (61.2%), DNMT3A (54.5.5%), JAK2 (4.7%) and quantitative PCR for RUNX1- ETO fusion (13.2%). Cohort A comprised 262 (72.7%) patients who underwent PCR-based mutation testing only. Cohort B consisted of 101 (27.8%) patients who underwent PCR-based mutation testing in addition to NGS myeloid panel analysis. In the entire cohort of 363 patients, we found FLT3-ITD mutations in 85 patients (23.4%) and NPM1 mutations in 68 (18.7%). 36 patients (9.9%) harboured both FLT3-ITD and NPM1 mutations together. In Cohort A, FLT3-ITD detected 26.7% of patients, and 20.2% had NPM1 mutation, while 40% had no detectable mutations by conventional PCR. On the other hand, FLT3-ITD was detected in 14.9% of patients by both NGS and conventional PCR and in 14.9% of patients with NPM1. When comparing Cohort A and Cohort B, Cohort B had more mutations in genes that play an important role in myeloid malignancies, which might have better risk stratification and precision, including TP53 in 13.9% of patients and RUNX1 in 18.8% of patients and ASXL1 in 9.9% of patients. Moreover, NGS pick up more mutations in CEBPA, c-KIT, WT1, IDH1 and JAK2 genes compared to conventional PCR. Within cohort A, 9.2% of patients had normal cytogenetic testing results with no detectable mutations, whereas in cohort B, only 1% of patients had normal karyotype and molecular testing. Furthermore, six mutations were detected only by NGS but not PCR in FLT3-ITD, CEBPA, c-KIT, IDH2, WT1 and DNMT3A in 5.9% of patients. Cohorts A and B were also categorised into ELN risk groups using PCR, sequencing, and cytogenetics testing. It was found that patients at adverse risk had shorter overall survival compared to those at intermediate or favourable risk in both cohorts, with p-values of 0.030 and 0.0007, respectively (Figure 1). The use of NGS was found to be more effective than conventional testing in identifying patients with adverse risk, with a hazard ratio for death of 0.22 (95% CI, 0.08989-0.5732) compared to a hazard ratio of 0.66 (95% CI, 0.4352 -1.031) for conventional PCR testing. Conclusion In this study, we present the mutational profile of AML in young Saudi patients and identify certain frequent mutations in this population. The study presents the largest molecular profiling to our knowledge of this population. The study emphasises the need for integration of NGS to enhance risk stratification and precision, enable better characterisation of high-risk patients, and improve the potential for targeted treatments.

Penile melanoma: a pathological report of two cases

BackgroundPenile melanoma (PM) is a rare tumor, accounting for less than 2% of all penile cancers. PM can occur on the surface of the glans, foreskin, and opening of the urethra. Furthermore, PM primarily affects older individuals and is not associated with sun exposure. Currently, there is no specific staging system for genitourinary tract melanomas, so these tumors are typically staged using the criteria for cutaneous melanoma. Limited data in the literature suggests that PM generally has a poor clinical prognosis.Case presentationHere, we describe two cases of PM. The first case affected a 62-year-old male who presented with hematuria and a painful tumor in the distal urethra, leading to a suspicion of penile cancer. The second case involved a 68-year-old male who noticed a rapidly evolving dark spot on his foreskin. Histological analysis confirmed the presence of melanoma in both patients. The tumors showed a diffuse and strong PRAME-positivity and lacked BRAF mutation in both cases. Additionally, the second tumor harbored an activating CKIT mutation. An enhanced PD-L1 expression was observed in both tumors.ConclusionsWe presented two rare forms of mucosal melanoma and highlighted the entities in the differential diagnosis. Based on our experience PRAME is a helpful marker for making the diagnosis of PM, and PD-L1 can predict the success of the immunotherapy. We also emphasize the need for an organ-specific staging system for PMs.

Connective tissue mast cells store and release noradrenaline

Mast cells are present in mucosal and connective tissues throughout the body. They synthesize and release a wide variety of bioactive molecules, such as histamine, proteases, and cytokines. In this study, we found that a population of connective tissue mast cells (CTMCs) stores and releases noradrenaline, originating from sympathetic nerves. Noradrenaline-storing cells, not neuronal fibers, were predominantly identified in the connective tissues of the skin, mammary gland, gastrointestinal tract, bronchus, thymus, and pancreas in wild-type mice but were absent in mast cell–deficient W-sash c-kit mutant KitW−sh/W−sh mice. In vitro studies using bone marrow–derived mast cells revealed that extracellular noradrenaline was taken up but not synthesized. Upon ionomycin stimulation, noradrenaline was released. Electron microscopy analyses further suggested that noradrenaline is stored in and released from the secretory granules of mast cells. Finally, we found that noradrenaline-storing CTMCs express organic cation transporter 3 (Oct3), which is also known as an extraneuronal monoamine transporter, SLC22A3. Our findings indicate that mast cells may play a role in regulating noradrenaline concentration by storing and releasing it in somatic tissues.

Favorable Toxicity and Local Control with Ultrahypofractionated Radiation Therapy (UH-RT) for Melanoma of the Lower Genital Tract (LGT)

To report our experience using UH-RT +/- immunotherapy (IO) in women with melanoma of the LGT. We retrospectively identified 23 patients who received UH-RT to primary tumor for vulvovaginal melanoma from 2012 to 2022. Median age was 69 years (IQR: 62-76). Stage included localized, node positive, or metastatic. 18 (78%) had tumors involving the vagina/cervix and 5 (22%) had vulvar tumors. 6 patients had c-KIT mutations; 13 patients were wild-type; 4 patients were unknown. 12 (52%) were treated at initial presentation (cohort A) and 11 (48%) at local progression/recurrence following prior therapy (cohort B). In cohort A, most (n = 11) received concurrent IO. In cohort B, 3 recurred after surgery alone, 4 after systemic therapy alone and 4 after surgery and systemic therapy. RT consisted of 6 Gy x 6 (n = 11), 6 Gy x 5 (n = 10) and 5 Gy x 5-6 (n = 2) delivered to the primary tumor + 0.5 cm margin. Patients initiated IO either ≥3 months preRT (n = 8), concurrent with RT (n = 12) or ≥3 months following RT (n = 2). 1 patient in cohort B did not receive IO. Toxicity was graded using CTCAE v 5. Overall survival (OS) was measured from end of RT. Cumulative incidence of local progression was measured from end of RT. Kaplan-Meier method and Cox regression were used for survival analyses. Landmark method was used for timing of IO. Median follow-up as determined by reverse Kaplan-Meier method was 60 months (95% CI: 37-N/A). Overall incidence of acute/late grade 2+ toxicity for the entire cohort was 34%. Grade 2 acute toxicity included: dermatitis (n = 3), urinary (n = 2), vaginitis (n = 2) and diarrhea (n = 1). 3 patients experienced grade 3 acute dermatitis. 1 patient experienced late grade 2 vaginitis. No grade 3 or 4 toxicity was noted. No significant differences in toxicity were noted between RT regimens. Local disease control was achieved in 61% of patients. Local only, local and distant, and distant-only progression were seen in 17%, 22%, and 30% of patients respectively. 2-year cumulative incidence of local progression was 33% for the whole cohort, 28% for cohort A, and 36% for cohort B (p = 0.4). On UVA, factors associated with local progression were vulvar disease (p = 0.02) and c-KIT mutation (p = 0.011). No significant difference in local control was noted based on biologic effective dose (BED10 < = 48Gy vs >48Gy) (p = 0.06). Median OS for entire cohort, cohort A, and cohort B were 46, 72, and 30 months, respectively. 2-year survival (95% CI) was 67% (50%-91%), 73% (51%-100%), and 64% (41%-99%) respectively. On UVA, non-local disease at time of RT (p = 0.016) and receipt of IO ≥3 months prior to RT (p = 0.030) had worse OS. UH-RT+/- IO for melanoma of the LGT is well-tolerated with local disease control achieved in 61% of patients. Vulvar primary and c-Kit mutations were associated with worse local control. Additional follow-up may be necessary to determine the value of dose escalation.

C-Kit Receptors as a Therapeutic Target in Cancer: Current Insights.

c-Kit is a type III receptor tyrosine kinase (RTK) that has an essential role in various biological functions including gametogenesis, melanogenesis, hematopoiesis, cell survival, and apoptosis. c-KIT aberrations, either overexpression or loss-of-function mutations, have been implicated in the pathogenesis and development of many cancers, including gastrointestinal stromal tumors, mastocytosis, acute myeloid leukemia, breast, thyroid, and colorectal cancer, making c-KIT an attractive molecular target for the treatment of cancers. Therefore, a lot of effort has been put into investigating the utility of tyrosine kinase inhibitors for the management of c-KIT mutated tumors. This review of the literature illustrates the role of c-KIT mutations in many cancers, aiming to provide insights into the role of TKIs as a therapeutic option for cancer patients with c-KIT aberrations. In conclusion, c-KIT is implicated in different types of cancer, and it could be a successful molecular target; however, proper detection of the underlying mutation type is required before starting the appropriate personalized therapy.