Tyrosine Kinase Gene Research Articles

ALK, ROS1, RET and NTRK1-3 Gene Fusions in Colorectal and Non-Colorectal Microsatellite-Unstable Cancers.

This study aimed to conduct a comprehensive analysis of actionable gene rearrangements in tumors with microsatellite instability (MSI). The detection of translocations involved tests for 5'/3'-end expression imbalance, variant-specific PCR and RNA-based next generation sequencing (NGS). Gene fusions were detected in 58/471 (12.3%) colorectal carcinomas (CRCs), 4/69 (5.8%) gastric cancers (GCs) and 3/65 (4.6%) endometrial cancers (ECs) (ALK: 8; RET: 12; NTRK1: 24; NTRK2: 2; NTRK3: 19), while none of these alterations were observed in five cervical carcinomas (CCs), four pancreatic cancers (PanCs), three cholangiocarcinomas (ChCs) and two ovarian cancers (OCs). The highest frequency of gene rearrangements was seen in KRAS/NRAS/BRAF wild-type colorectal carcinomas (53/204 (26%)). Surprisingly, as many as 5/267 (1.9%) KRAS/NRAS/BRAF-mutated CRCs also carried tyrosine kinase fusions. Droplet digital PCR (ddPCR) analysis of the fraction of KRAS/NRAS/BRAF mutated gene copies in kinase-rearranged tumors indicated that there was simultaneous co-occurrence of two activating events in cancer cells, but not genetic mosaicism. CRC patients aged above 50 years had a strikingly higher frequency of translocations as compared to younger subjects (56/365 (15.3%) vs. 2/106 (1.9%), p = 0.002), and this difference was particularly pronounced for tumors with normal KRAS/NRAS/BRAF status (52/150 (34.7%) vs. 1/54 (1.9%), p = 0.001). There were no instances of MSI in 56 non-colorectal tumors carrying ALK, ROS1, RET or NTRK1 rearrangements. An analysis of tyrosine kinase gene translocations is particularly feasible in KRAS/NRAS/BRAF wild-type microsatellite-unstable CRCs, although other categories of tumors with MSI also demonstrate moderate occurrence of these events.

Gènes de fusion à activité tyrosine kinase : une série de quatre cas de gliome hémisphérique infantile

Infant-type hemispheric gliomas belong to pediatric-type diffuse high-grade gliomas according to the 2021 WHO classification of central nervous system tumors. They are characterized by tyrosine kinase gene rearrangements (NTRK1/2/3, ALK, ROS1, MET). The aim of the study was to describe the clinical, histopathologic, and molecular characteristics of such tumors, and to provide a review of the literature. This retrospective series comprises four cases of infant-type hemispheric glioma diagnosed at Angers University Hospital between 2020 and 2022. The diagnosis was suspected based on morphology and immunohistochemistry and was confirmed by molecular biology techniques. The most common clinical sign was raised intracranial pressure. Imaging showed a large cerebral hemispheric tumor with contrast enhancement. Microscopic examination revealed diffuse astrocytoma with high-grade features, sometimes with neuronal or pseudo-ependymal differentiation. Identification of a gene fusion involving a tyrosine kinase gene allowed to make a definitive diagnosis of infant-type hemispheric glioma. Infant-type hemispheric gliomas are rare and present as large cerebral hemispheric tumors in very young children. Searching for a tyrosine kinase gene fusion should be systematic when dealing with a high-grade glioma in an infant. Importantly, these gene fusions are therapeutic targets. The impact of targeted therapies on patient survival should be evaluated in future prospective studies.

Golgi retention and oncogenic KIT signaling via PLCγ2-PKD2-PI4KIIIβ activation in gastrointestinal stromal tumor cells

Most gastrointestinal stromal tumors (GISTs) develop due to gain-of-function mutations in the tyrosine kinase gene, KIT. We recently showed that mutant KIT mislocalizes to the Golgi area and initiates uncontrolled signaling. However, the molecular mechanisms underlying its Golgi retention remain unknown. Here, we show that protein kinase D2 (PKD2) is activated by the mutant, which causes Golgi retention of KIT. In PKD2-inhibited cells, KIT migrates from the Golgi region to lysosomes and subsequently undergoes degradation. Importantly, delocalized KIT cannot trigger downstream activation. In the Golgi/trans-Golgi network (TGN), KIT activates the PKD2-phosphatidylinositol 4-kinase IIIβ (PKD2-PI4KIIIβ) pathway through phospholipase Cγ2 (PLCγ2) to generate a PI4P-rich membrane domain, where the AP1-GGA1 complex is aberrantly recruited. Disruption of any factors in this cascade results in the release of KIT from the Golgi/TGN. Our findings show the molecular mechanisms underlying KIT mislocalization and provide evidence for a strategy for inhibition of oncogenic signaling.

ROS1-Rearranged Lung Adenocarcinoma: From Molecular Genetics to Target Therapy

Non-small-cell lung cancer (NSCLC) is a heterogeneous group of diseases accounting for 80–85% of lung cancers. A molecular subset of NSCLC (1–2.5%) harboring molecular rearrangements of the tyrosine kinase gene ROS1 is defined as ROS1-positive and is almost exclusively diagnosed in patients with lung adenocarcinoma histology, predominantly nonsmokers. ROS1 is constitutively activated by molecular rearrangements and acts as a main driver of lung carcinogenesis. These findings have provided a strong rationale for the clinical use of tyrosine kinase inhibitors that target ROS1; these inhibitors block ROS1-positive NSCLC and provide clinical benefit. Crizotinib was introduced as a first-line treatment for ROS1-positive NSCLCs, with 75–80% of patients responding and a PFS of about 20 months. More recently developed ROS1-TKIs, such as entrectinib, lorlatinib, taletrectinib, repotrectinib and NVL-520, are active against some resistant ROS1 mutants appearing during crizotinib therapy and more active against brain metastases, frequent in ROS1-positive NSCLC. The development of resistance mechanisms represents a great limitation for the targeted treatment of ROS1-positive NSCLCs with TKIs.

Overexpression of Bruton Tyrosine Kinase Inhibits the Proliferation, Migration, and Invasion of Non-Small Cell Lung Cancer Cells.

Lung cancer is one of the most lethal malignant tumors in the world. Non-small cell lung cancer (NSCLC) is the most common pathological subtype. However, the molecular mechanism of NSCLC progress is still unclear. We extracted the expression data of the Bruton's tyrosine kinase (BTK) gene in NSCLC tissues from the TCGA database. The results of paired t-test showed that the BTK gene was significantly underexpressed in NSCLC tissues. To further verify the above results, we detected the expression of the BTK gene in NSCLC cell lines A549, H1299, and H1650 at the RNA and protein levels by real-time fluorescent quantitative polymerase chain reaction and Western Blot analysis, respectively. The results showed that BTK was low expressed in NSCLC tissues and cells. More importantly, the expression of the BTK gene is also significantly related to the patient's age, gender, tumor range (T), lymph node invasion (N), tumor stage, and prognosis, and its expression level gradually decreases with the progress of the disease. It is speculated that BTK may be an independent prognostic factor of NSCLC. Our experimental results are consistent with the above clinical correlation analysis results. Overexpression of BTK can significantly inhibit the proliferation, migration, and invasion of NSCLC cells and can block the G0/G1 tumor cell cycle, indicating that overexpression of BTK can inhibit the growth, migration, and invasion of NSCLC cells.

Myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase fusion genes: A workshop report with focus on novel entities and a literature review including paediatric cases.

Myeloid/lymphoid neoplasms with eosinophilia (M/LN-eo) and tyrosine kinase (TK) gene fusions are a rare group of haematopoietic neoplasms with a broad range of clinical and morphological presentations. Paediatric cases have increasingly been recognised. Importantly, not all appear as a chronic myeloid neoplasm and eosinophilia is not always present. In addition, standard cytogenetic and molecular methods may not be sufficient to diagnose M/LN-eo due tocytogenetically cryptic aberrations. Therefore, additional evaluation with fluorescence in-situ hybridisation and other molecular genetic techniques (array-based comparative genomic hybridisation, RNA sequencing) are recommended for the identification of specific TK gene fusions. M/LN-eo with JAK2 and FLT3-rearrangements and ETV6::ABL1 fusion were recently added as a formal member to this category in the International Consensus Classification (ICC) and the 5th edition of the WHO classification (WHO-HAEM5). In addition, other less common defined genetic alterations involving TK genes have been described. This study is an update on M/LN-eo with TK gene fusions with focus on novel entities, as illustrated by cases submitted to the Bone Marrow Workshop, organised by the European Bone Marrow Working Group (EBMWG) within the frame of the 21st European Association for Haematopathology congress (EAHP-SH) in Florence 2022. A literature review was performed including paediatric cases of M/LN-eo with TK gene fusions.

Association Between Bruton's Tyrosine Kinase Gene Overexpression and Risk of Lymphoma in Primary Sjögren's Syndrome.

We undertook this study to analyze whole blood gene expression and to investigate the role of B cell genes in primary Sjögren's syndrome-related non-Hodgkin lymphoma (primary SS-NHL). Peripheral whole blood samples were collected from 345 well-phenotyped patients with primary SS enrolled in the prospective Assessment of Systemic Signs and Evolution in Sjögren's Syndrome (ASSESS) cohort. Transcriptomic analysis was performed using human Clariom S Arrays (Affymetrix). In our primary analysis, we considered patients with incident lymphoma (i-primary SS-NHL) as the case group and all patients without lymphoma as the comparison group. In our sensitivity analyses, we considered all patients with primary SS-NHL, including those with a history of lymphoma (h-primary SS-NHL), as the case group and primary SS patients without lymphoma, stratified on their risk factors of lymphoma, as the comparison group. Twenty-one patients with primary SS-NHL (including 8 with i-primary SS-NHL and 13 h-primary SS-NHL) were eligible for transcriptomic analysis; we compared these patients to 324 primary SS controls without lymphoma, including 110 with moderate to severe disease activity and 61 with no risk factor of lymphoma. Functional clustering analyses revealed an enrichment of genes related to innate and adaptive immunity, including B cell-related genes. Bruton's tyrosine kinase (BTK) and a proliferation-inducing ligand (APRIL) genes were overexpressed before the occurrence of lymphoma in patients with incident lymphoma compared with patients without lymphoma. In sensitivity analyses, BTK was consistently up-regulated across all comparisons performed. BTK expression was associated with risk of lymphoma on multivariate analyses, which considered 9 validated predictors of lymphoma in primary SS. BTK and APRIL were overexpressed in the peripheral blood of primary SS patients prior to lymphoma. The association between BTK, APRIL, and primary SS-NHL requires confirmation in other prospective cohorts.

High-grade glioma in infants and young children is histologically, molecularly, and clinically diverse: Results from the SJYC07 trial and institutional experience.

High-grade gliomas (HGG) in young children pose a challenge due to favorable but unpredictable outcomes. While retrospective studies broadened our understanding of tumor biology, prospective data is lacking. A cohort of children with histologically diagnosed HGG from the SJYC07 trial was augmented with nonprotocol patients with HGG treated at St. Jude Children's Research Hospital from November 2007 to December 2020. DNA methylome profiling and whole genome, whole exome, and RNA sequencing were performed. These data were integrated with histopathology to yield an integrated diagnosis. Clinical characteristics and preoperative imaging were analyzed. Fifty-six children (0.0-4.4 years) were identified. Integrated analysis split the cohort into four categories: infant-type hemispheric glioma (IHG), HGG, low-grade glioma (LGG), and other-central nervous system (CNS) tumors. IHG was the most prevalent (n = 22), occurred in the youngest patients (median age = 0.4 years), and commonly harbored receptor tyrosine kinase gene fusions (7 ALK, 2 ROS1, 3 NTRK1/2/3, 4 MET). The 5-year event-free (EFS) and overall survival (OS) for IHG was 53.13% (95%CI: 35.52-79.47) and 90.91% (95%CI: 79.66-100.00) vs. 0.0% and 16.67% (95%CI: 2.78-99.74%) for HGG (p = 0.0043, p = 0.00013). EFS and OS were not different between IHG and LGG (p = 0.95, p = 0.43). Imaging review showed IHGs are associated with circumscribed margins (p = 0.0047), hemispheric location (p = 0.0010), and intratumoral hemorrhage (p = 0.0149). HGG in young children is heterogeneous and best defined by integrating histopathological and molecular features. Patients with IHG have relatively good outcomes, yet they endure significant deficits, making them good candidates for therapy de-escalation and trials of molecular targeted therapy.

Inflammatory myofibroblastic tumor of the distal common bile duct: Literature review with focus on pathological examination.

Inflammatory myofibroblastic tumor (IMT) of the biliary tract is rare, and often difficult to diagnose or to distinguish from other tumors due to its atypical clinical presentation and nonspecific radiological features. Histologically, IMTs are (myo)fibroblastic neoplasms with a prominent inflammatory infiltrate. They are characterized by receptor tyrosine kinase gene rearrangements, most often involving an anaplastic lymphoma kinase (ALK) translocation. The final diagnosis of IMT depends on histopathology and immunohistochemical examination. In this manuscript, we provide a clinical and morphomolecular overview of IMT and the difficulties that may arise in using immunohistochemical and molecular techniques in diagnosing IMT.

Myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusions: reevaluation of the defining characteristics in a registry-based cohort

In a registry-based analysis of 135 patients with “myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusions” (MLN-TK; FIP1L1::PDGFRA, n = 78; PDGFRB, diverse fusions, n = 26; FGFR1, diverse, n = 9; JAK2, diverse, n = 11; ETV6::ABL1, n = 11), we sought to evaluate the disease-defining characteristics. In 81/135 (60%) evaluable patients, hypereosinophilia (>1.5 × 109/l) was observed in 40/44 (91%) FIP1L1::PDGFRA and 7/7 (100%) ETV6::ABL1 positive patients but only in 13/30 (43%) patients with PDGFRB, FGFR1, and JAK2 fusion genes while 9/30 (30%) patients had no eosinophilia. Monocytosis >1 × 109/l was identified in 27/81 (33%) patients, most frequently in association with hypereosinophilia (23/27, 85%). Overall, a blast phase (BP) was diagnosed in 38/135 (28%) patients (myeloid, 61%; lymphoid, 39%), which was at extramedullary sites in 18 (47%) patients. The comparison between patients with PDGFRA/PDGFRB vs. FGFR1, JAK2, and ETV6::ABL1 fusion genes revealed a similar occurrence of primary BP (17/104, 16% vs. 8/31 26%, p = 0.32), a lower frequency (5/87, 6% vs. 8/23, 35%, p = 0.003) of and a later progression (median 87 vs. 19 months, p = 0.053) into secondary BP, and a better overall survival from diagnosis of BP (17.1 vs. 1.7 years, p < 0.0008). We conclude that hypereosinophilia with or without monocytosis and various phenotypes of BP occur at variable frequencies in MLN-TK.

Diagnosis of a case of X-linked agammaglobulinemia with juvenile idiopathic arthritis and recurrent pneumonia in Bangladesh

Abstract X-linked agammaglobulinemia (XLA) is a rare hereditary primary immunodeficiency disorder caused by mutation in the Bruton’s tyrosine kinase (BTK) gene located in the Xq22 region of the X chromosome. It is characterized by absolute or marked deficiency of matured B-cells in circulation as well as decreased in all immunoglobulin (Ig) classes. We have reported one case who is a 48-month-old boy and suffering from recurrent pneumonia, skin abscess, otitis media, and swelling of the left knee joint. His serum Ig levels showed an IgM level of &lt;0.169 g/l, IgG 2.43 g/l, and IgA &lt;0.256 g/l. Immunophenotyping of lymphocyte subsets showed an absence of B-cells. Intracellular BTK protein expression in monocytes by flow cytometry showed a markedly reduced mean fluorescence index which confirmed the diagnosis of XLA. Antibiotics with intravenous Ig therapy were started.

A comprehensive analysis of infantile central nervous system tumors to improve distinctive criteria for infant-type hemispheric glioma versus desmoplastic infantile ganglioglioma/astrocytoma.

Recent epigenomic analyses have revealed the existence of a new DNA methylation class (MC) of infant-type hemispheric glioma (IHG). Like desmoplastic infantile ganglioglioma/astrocytoma (DIG/DIA), these tumors mainly affect infants and are supratentorial. While DIG/DIA is characterized by BRAF or RAF1 alterations, IHG has been shown to have receptor tyrosine kinase (RTK) gene fusions (ALK, ROS1, NTRK1/2/3, and MET). However, in this rapidly evolving field, a more comprehensive analysis of infantile glial/glioneuronal tumors including clinical, radiological, histopathological, and molecular data is needed. Here, we retrospectively investigated data from 30 infantile glial/glioneuronal tumors, consecutively compiled from our center. They were analyzed by two experienced pediatric neuroradiologists in consensus, without former knowledge of the molecular data. We also performed a comprehensive clinical, and histopathological examination (including molecular evaluation by next-generation sequencing, RNA sequencing, and fluorescence in situ hybridization [FISH] analyses), as well as DNA methylation profiling for the samples having sufficient material available. The integrative histopathological, genetic, and epigenetic analyses, including t-distributed stochastic neighbor embedding (t-SNE) analyses segregated tumors into 10 DIG/DIA (33.3%), six IHG (20.0%), three gangliogliomas (10.0%), two pleomorphic xanthoastrocytomas (6.7%), two pilocytic astrocytomas (6.7%), two supratentorial ependymomas, ZFTA fusion-positive (6.7%), two supratentorial ependymomas, YAP1 fusion-positive (6.7%), two embryonal tumors with PLAGL2-family amplification (6.7%), and one diffuse low-grade glioma, MAPK-pathway altered. This study highlights the significant differential features, in terms of histopathology (leptomeningeal infiltration, intense desmoplasia and ganglion cells in DIG/DIA and necrosis, microvascular proliferation, and siderophages in IHG), and radiology between DIG/DIA and IHG. Moreover, these results are consistent with the literature data concerning the molecular dichotomy (BRAF/RAF1 alterations vs. RTK genes' fusions) between DIG/DIA and IHG. This study characterized histopathologically and radiologically two additional cases of the novel embryonal tumor characterized by PLAGL2 gene amplification.

METB-02. DECIPHERING THE CELLULAR HETEROGENEITY OF INFANT-TYPE HEMISPHERIC GLIOMAS USING SINGLE-NUCLEI MULTI-OMICS

Abstract Infant-type hemispheric gliomas (IHGs) have recently been recognized as a new tumor entity. Compared to other types of pediatric gliomas, most IHGs distinctively harbor a fusion in a cluster of receptor tyrosine kinase (RTK) genes: the NTRK family, ROS1, ALK, or MET. Clinically, IHG patients appear to be associated with better outcomes compared to older children with high-grade tumors. While large-scale genomic studies have helped uncovered the complex molecular landscape and clinical features of IHGs, little is known about the underlying biology – specifically how tumor heterogeneity may explain the spectrum of clinical presentations and progression of the disease. Using single-nuclei multi-omic (RNA/ATAC-seq) profiling, we assembled a comprehensive atlas of IHG tumor cells from a cohort of patients spanning different age groups and RTK fusion subtypes. We measured that tumor single-nuclei transcriptomes clustered into distinct subpopulations and contained genes expressed by the normal brain cell lineages. Data integration with single-cell atlases from the developing brain allowed us to rank tumor cell subpopulations according to their developmental stage, with age- and fusion-specific differences. Using trajectory inference and gene expression velocity modeling, we describe a hierarchical and dynamic organization between subpopulations, potentially illustrating the role of phenotypic plasticity in glioma formation. Moreover, we measured in fragments of open chromatin a cell-type specific enrichment of binding sites for transcription factors known to regulate brain cell maturation. Taken together, our multi-modal atlas describes the cellular and functional heterogeneity of IHGs, paving the way towards a greater understating of its unique biology and clinical consequences.

HGG-03. HIGH-GRADE GLIOMA IN YOUNG CHILDREN IS HISTOLOGICALLY, MOLECULARLY, AND CLINICALLY DIVERSE—RESULTS FROM THE SJYC07 TRIAL AND INSTITUTIONAL EXPERIENCE

Abstract BACKGROUND High-grade gliomas (HGG) in young children pose a challenge due to favorable but unpredictable outcomes. While retrospective studies have broadened our understanding of tumor biology, prospective data regarding outcomes and molecular predictors is lacking. METHODS Young children (0-5 years) histologically diagnosed with HGG and enrolled on the SJYC07 trial or treated at St Jude Children’s Research Hospital from November 2007 to December 2020 were included. DNA methylation, whole genome (WGS), whole exome (WES), and RNA (RNA-seq) sequencing were performed on available samples and these data were integrated with standard histopathological tests to yield a diagnosis. Clinical characteristics and pre-operative imaging were analyzed. RESULTS Fifty-six children (0.0-4.4 years) were identified. Integrated molecular and histopathological analysis split the tumors into four categories: infant-type hemispheric glioma (IHG), HGG, low-grade glioma (LGG), and other-central nervous system (CNS) tumors (i.e., CNS embryonal tumors, CNS sarcomas, neuroepithelial tumors). IHG was the most prevalent (N=22), occurred in the youngest patients (median age 0.4 years; 0-4.4 years), and commonly harbored receptor tyrosine kinase gene fusions (7 ALK, 2 ROS1, 3 NTRK1/2/3, 4 MET). The 5-year event-free (EFS) and overall survival (OS) for IHG was 53.13% (95% CI: 35.52 -79.47) and 90.91% (95%CI: 79.66-100.00) vs. 0.0% and 16.67% (95% CI: 2.78-99.74%) for HGG (p= 0.0043, 0.00013). EFS and OS were not different between IHG and LGG (p=0.95, 0.43). Imaging review of HGG, LGG , IHG and Other CNS tumors showed that IHGs are associated with circumscribed margins (p=0.0047), hemispheric location (p=0.0010), and hemorrhage (p=0.0149). CONCLUSIONS HGG in young children is not a single-entity and is best defined by an integrated histopathological and molecular diagnosis. While patients with IHGs display good survival, as compared to other pediatric HGGs, they still suffer severe treatment-related morbidities. Therefore, prompt consideration for reduced adjuvant and molecularly targeted therapies is warranted.

Bioinformatic analysis of gene expression data reveals Src family protein tyrosine kinases as key players in androgenetic alopecia.

Androgenetic alopecia (AGA) is a common progressive scalp hair loss disorder that leads to baldness. This study aimed to identify core genes and pathways involved in premature AGA through an in-silico approach. Gene expression data (GSE90594) from vertex scalps of men with premature AGA and men without pattern hair loss was downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) between the bald and haired samples were identified using the limma package in R. Gene ontology and Reactome pathway enrichment analyses were conducted separately for the up-regulated and down-regulated genes. The DEGs were annotated with the AGA risk loci, and motif analysis in the promoters of the DEGs was also carried out. STRING Protein-protein interaction (PPI) and Reactome Functional Interaction (FI) networks were constructed using the DEGs, and the networks were analyzed to identify hub genes that play could play crucial roles in AGA pathogenesis. The in-silico study revealed that genes involved in the structural makeup of the skin epidermis, hair follicle development, and hair cycle are down-regulated, while genes associated with the innate and adaptive immune systems, cytokine signaling, and interferon signaling pathways are up-regulated in the balding scalps of AGA. The PPI and FI network analyses identified 25 hub genes namely CTNNB1, EGF, GNAI3, NRAS, BTK, ESR1, HCK, ITGB7, LCK, LCP2, LYN, PDGFRB, PIK3CD, PTPN6, RAC2, SPI1, STAT3, STAT5A, VAV1, PSMB8, HLA-A, HLA-F, HLA-E, IRF4, and ITGAM that play crucial roles in AGA pathogenesis. The study also implicates that Src family tyrosine kinase genes such as LCK, and LYN in the up-regulation of the inflammatory process in the balding scalps of AGA highlighting their potential as therapeutic targets for future investigations.

The international consensus classification of eosinophilic disorders and systemic mastocytosis.

Based on new data and increased understanding of disease molecular genetics, the international consensus classification (ICC) has made several changes in the diagnosis and classification of eosinophilic disorders and systemic mastocytosis. Myeloid/lymphoid neoplasms with eosinophilia (M/LN-eo) and gene rearrangements have been renamed as M/LN-eo with tyrosine kinase gene fusions (M/LN-eo-TK). The category has been expanded to include ETV6::ABL1 and FLT3 fusions, and to accept PCM1::JAK2 and its genetic variants as formal members. The overlaps and differences between M/LN-eo-TK and BCR::ABL1-like B-lymphoblastic leukemia (ALL)/de novo T-ALL sharing the same genetic lesions are addressed. Besides genetics, ICC for the first time has introduced bone marrow morphologic criteria in distinguishing idiopathic hypereosinophilia/hypereosinophilic syndrome from chronic eosinophilic leukemia, not otherwise specified. The major diagnostic criteria for systemic mastocytosis (SM) in the ICC remain largely based on morphology, but several minor modifications/refinements have been made in criteria related to diagnosis, subclassification, and assessment of disease burden (B- and C-findings). This review is to focus on the ICC updates related to these disease entities, illustrated through changes related to morphology, molecular genetics, clinical features, prognosis, and treatment. Two practical algorithms are provided in navigating through the diagnosis and classification systems of hypereosinophilia and SM.

Feasibility and utility of the custom RNA-seq for the identification of therapeutic targets and diagnostic biomarkers in glioma.

e14029 Background: The detection of novel therapeutic targets is increasingly important in oncology. The Todai OncoPanel (TOP) RNA panel is a custom target RNA-seq using the junction capture method to maximize the sensitivity in detecting of known 456 fusion gene transcripts, which is scheduled to be approved for clinical application in Japan in April 2023. Above, TOP RNA panel interrogates aberrantly spliced transcripts and analyzes the expression profiles of 1,390 genes. Malignant brain tumors, including gliomas, require various molecular profiles to be classified based on the latest WHO classification criteria, while their poor prognosis also necessitates new therapeutic targets. In this study, we aimed to classify gliomas and identify the molecular targets by TOP RNA panel. Methods: Among 131 frozen tumor samples of malignant gliomas, 124 samples passed quality control for further validation and were subjected to TOP RNA panel to classify based on the molecular profiles and to identify the molecular targets. Fusion detection and RNA expression analysis were conducted with the original pipeline. Cluster analysis and Gene Set Enrichment Analysis (GSEA) were performed to identify gene sets specific for individual subtypes. Copy numbers of tyrosine kinase genes, MDM2 and CDK4 were evaluated by digital droplet PCR (ddPCR). Results: Among 58 cases of glioblastoma, gene fusions were detected in 11 cases (19.0%) including novel MET fusions, and overexpression of seven tyrosine kinase genes were observed in 21 cases (36.2%). Of the 34 overexpressed genes, gene amplification was observed in 17 genes (50%) by ddPCR. In contrast to IDH-wildtype glioblastoma, IDH-mutant tumors including astrocytomas and oligodendrogliomas hardly harbored fusion genes or gene overexpression. GSEA to compare astrocytomas and oligodendrogliomas identified that the gene sets related to 1p36 and 19q were relatively enriched in astrocytoma, suggesting that regional genomic DNA copy number alterations can be evaluated by gene expression analysis. Conclusions: TOP RNA panel is utilized not only for the detection of molecular targets but also for the molecular classification of glioma, both of which is essential for providing treatments optimized for the individual patients.

Open AccessLack of association between coat color abnormalities in Bali cattle (Bos javanicus) and the coding regions of the MC1R and KIT genes.

Coat color variations in cattle are known to be influenced by the melanocortin 1 receptor (MC1R) and receptor tyrosine kinase (KIT) genes. The presence of coat color abnormalities, such as white spots and albinism, in Bali cattle was the focus of this study. This study aimed to identify single nucleotide polymorphisms (SNPs) in the coding region of MC1R and exons 2 and 3 of KIT associated with coat color abnormalities in Bali cattle. The study included the analysis of 48 Bali cattle, including 20 individuals with standard coat color, 15 with white spots, and 13 with albinism. Total DNA was extracted using a DNA Extraction Kit, and MC1R (coding region) and KIT (exons 2 and 3) gene amplifications were analyzed using forward and reverse primers with polymerase chain reaction product lengths of 1071, 234, and 448 bp, respectively. The determination of MC1R and KIT gene diversity was analyzed through direct sequencing. Melanocortin 1 receptor and KIT gene sequence data were analyzed using BioEdit and MEGA6 to identify SNPs associated with standard and abnormal coat color phenotypes (white-spotted and albino) in Bali cattle. No SNPs associated with coat color abnormalities were found in the coding region of MC1R and exons 2 and 3 of KIT genes in Bali cattle. However, the intron two regions of KIT contained the SNP g.70208534A>G, which showed a high degree of diversity. The AA genotype frequency was highest in albino Bali cattle, whereas the G allele frequency was highest and the A allele frequency was lowest in white-spotted Bali cattle. The results indicated that standard, white-spotted, and albino coat colors in Bali cattle could not be distinguished by analyzing the MC1R and KIT genes.

Novel LTK fusions based on NGS sequencing data in Chinese patients with solid tumors.

3144 Background: Leukocyte receptor tyrosine kinase ( LTK) gene has the same kinase domain (PTKc_ALK_LTK) as ALK, and could functionally response to ALK inhibitors such as lorlatinib. Previous study reported that CLIP1-LTK fusion was a novel oncogenic driver mutation in lung cancer (occur in 0.4% of non-small cell lung cancer), which was sensitive to the ALK tyrosine kinase inhibitor lorlatinib. So far, LTK fusion has been rarely reported. Methods: A total of 11 Chinese solid tumor patients were reviewed, including 6 cases of LTK positive rearrangements in DNA and 5 cases of LTK positive fusion in RNA. FFPE samples were collected for NGS-based 450 cancer gene panel detection in both DNA and RNA level, and matched blood samples were used as normal control to filter out germline mutations. LTK fusions were analyzed by OrigiFus algorithm. Results: We found 6 patients with LTK rearrangements by DNA-based NGS detection, including lung adenocarcinoma, colorectal cancer, stomach cancer, spindle cell sarcoma of small intestine, adenocarcinoma of the pancreas, and cancer of unknown primary, and 5 soft tissue sarcoma patients with RPAP1 E25- LTK E2 fusions by RNA-based NGS detection. We analyzed the patterns of partner genes and breakpoints of the 6 LTK rearrangements. The partner genes included NUSAP1 (n=2), NDUFAF1 (n=1), LOC105370802 (n=1), EHD4 (n=1), and AGBL1 (n=1). All these partner genes were located on the same chromosome as LTK, rather than CLIP1, which was identified as a translocation. The breakpoints on LTK included exon20 (n=2), intron1 (n=2), exon6 (n=1), and exon10 (n=1). Five of the 6 fusions consisted of a complete PTKc_ALK_LTK domain. Among the 6 LTK rearrangements, LTK E20- NUSAP1 E2 was predicted as a fusion. Interestingly, this clinical real-world sample also harbored a classic NTRK1 fusion, LMNA E2- NTRK1 E11. The other NUSAP1- LTK was predicted to have a transcript of 3’-3’, but one of the breakpoints was observed at LTK exon6, which could be located at the kinase domain, so the possibility of eventual fusion cannot be excluded. The two NUSAP1-LTK fusions were found in a stomach tumor and a soft tissue sarcoma, respectively. One non-small-cell lung cancer (NSCLC) patient had a breakpoint detected on LTK exon10, which is the same as the exon of CLIP1- LTK reported. Conclusions: This study revealed novel LTK fusions/rearrangements and their cancer distribution in Chinese patients with solid tumors. We gave the details of these fusions/rearrangements which enrich our understanding of the LTK fusion. Although the small number of cases, our analysis promoted the attention on LTK and its potential value of drug research and clinical treatment in pan-cancer.

The Maverick trial: A phase 2 study of abivertinib in patients (pts) with metastatic castration resistant prostate cancer (mCRPC).

TPS5106 Background: Abivertinib is a potent, small molecule third-generation tyrosine kinase inhibitor (TKI) of epidermal growth factor receptor (EGFR), Bruton tyrosine kinase (BTK) receptor, and bone marrow tyrosine kinase gene on chromosome X (BMX). Abivertinib irreversibly binds to the BTK receptor, preventing the phosphorylation of the receptor, and also BMX. The adrenal-permissive HSD3B1(1245C) allele, which is present in upwards of 50% of men with prostate cancer, encodes a 3βHSD1 enzyme missense that up-regulates the rate-limiting step of androgen biosynthesis from extragonadal precursor steroids and promotes poor clinical outcomes. 3βHSD1 must be phosphorylated by BMX for androgen biosynthesis. Preclinical studies suggest BMX inhibition blocks 3βHSD1, androgen biosynthesis and CRPC in xenograft models. These provide the rationale for use of the combination of abivertinib and abiraterone to block residual androgen synthesis that escapes abiraterone inhibition. Methods: The Maverick Trial is a multicenter, open-label phase 2 study within the US Dept of Defense Prostate Cancer Clinical Trials Consortium (DOD PCCTC) of abivertinib with abiraterone in pts with mCRPC harboring the adrenal-permissive HSD3B1(1245C) allele (germline heterozygous or homozygous). HSD3B1 status will be confirmed centrally prior to enrollment via CLIA testing at the Cleveland Clinic. The study includes two cohorts: abiraterone-naïve and abiraterone-progressing. There will be cap of 50% of accrual in each cohort for pts heterozygous for the HSD3B1(1245C) allele. An interim futility analysis is embedded in each cohort, and toxicity rates will be continuously monitored for early stoppage according to predefined rules. Pts receive continuous treatment with abivertinib 200 mg BID with abiraterone 1000 mg QD + prednisone 5 mg BID until radiographic progression, unacceptable toxicity, intercurrent illness, or other reason, such as subject withdrawal. The primary endpoint is 6-month rPFS defined as percent of subjects alive and without progression by RECIST version 1.1 for measurable disease and PCWG3 criteria for bone metastases. Secondary and exploratory endpoints include objective response rate, duration of response, PSA progression, pharmacokinetics, pharmacodynamic tissue changes, and mechanisms of response and resistance to therapy via sequential tissue and blood sampling. The study is currently open at 1 site and will activate at 9 additional sites. It is sponsored by Sorrento Therapeutics, Inc, and managed by the Prostate Cancer Clinical Trials Consortium. Trial Registration: NCT05361915 Funding Source: Sorrento Therapeutics, Inc, the trial’s sponsor who is funding the trial. Clinical trial information: NCT05361915 .