JAK2 Mutation Research Articles

Predictors of clinical outcome in myeloproliferative neoplasm, unclassifiable: A Bone Marrow Pathology Group study.

Myeloproliferative neoplasm, unclassifiable (MPN-U, revised to MPN, not otherwise specified in the fifth edition of the World Health Organization classification) is a heterogeneous category of primary marrow disorders with clinical, morphologic, and/or molecular features that preclude classification as a more specific MPN subtype due to stage at diagnosis, overlapping features between MPN subtypes, or the presence of coexisting disorders. Compared with other MPN subtypes, the contribution of the mutational landscape in MPN-U in conjunction with other clinical and morphologic biomarkers to prognosis has been less well investigated. We performed a multicenter, retrospective study of MPN-U (94 cases) to better define the clinicopathologic features, genetic landscape, and clinical outcomes, including subgroups of early-stage, advanced-stage, and coexisting disorders. The Dynamic International Prognostic Scoring System (DIPSS) plus scoring system was applied to assess its relevance to MPN-U prognosis. Multivariate analysis demonstrated bone marrow blast count and DIPSS plus score as statistically significant in predicting overall survival. Univariate analysis identified additional potential poor prognostic markers, including abnormal karyotype and absence of JAK2 mutation. Secondary mutations were frequent in the subset analyzed by next-generation sequencing (26/37 cases, 70.3%) with a borderline association between high molecular risk mutations and overall survival. This study, as one of the largest of MPN-U studies incorporating both clinicopathologic and molecular data, moves toward identification of biomarkers that better predict prognosis in this heterogeneous category.

Omenn Syndrome in Two Infants with Different Hypomorphic Variants in Janus Kinase 3

Biallelic null or hypomorphic variants in JAK3 cause SCID and less frequently Omenn syndrome. We investigated homozygous hypomorphic JAK3 mutations in two patients, and expression and function of a novel JAK3R431P variant in Omenn syndrome. Immunophenotyping of PBMC from the patient with the novel JAK3R431P variant was undertaken, by flow cytometry and Phosflow after stimulation with IL-2, IL-7, and IL-15. JAK3 expression was investigated by Western blotting. We report two patients with homozygous hypomorphic JAK3 variants and clinical features of Omenn syndrome. One patient had a previously described JAK3R775H variant, and the second had a novel JAK3R431P variant. One patient with a novel JAK3R431P variant had normal expression of JAK3 in immortalised EBV-LCL cells but reduced phosphorylation of STAT5 after stimulation with IL-2, IL-7, and IL-15 consistent with impaired kinase activity. These results suggest the JAK3R431P variant to be hypomorphic. Both patients are alive and well after allogeneic haematopoietic stem cell transplantation. They have full donor chimerism, restitution of thymopoiesis and development of appropriate antibody responses following vaccination. We expand the phenotype of hypomorphic JAK3 deficiency and demonstrate the importance of functional testing of novel variants in disease-causing genes.

Turn It Off! Genetic Switch System Suggests Targeting of Mutant JAK2 Reverses Myeloproliferative Neoplasms

Turn It Off! Genetic Switch System Suggests Targeting of Mutant JAK2 Reverses Myeloproliferative Neoplasms

ADAMTS13, von Willebrand Factor, Platelet Microparticles, Factor VIII, and Impact of Somatic Mutations in the Pathogenesis of Splanchnic Vein Thrombosis Associated with BCR-ABL-Negative Myeloproliferative Neoplasms.

Myeloproliferative neoplasms (MPNs) are often associated with splanchnic vein thrombosis (SVT). Not all the factors involved in the thrombotic tendency are currently known. This study aims to evaluate a possible association between ADAMTS13, von Willebrand factor (VWF), platelet microvesicles (MV), and factor VIII activity (FVIII:C) with thrombotic events in MPN patients. In total, 36 consecutive MPN patients with SVT were enrolled. The MPNs were diagnosed based on clinical characteristics and one or more gene mutations among JAK-2, CALR, and MPL. As controls, 50 randomly selected patients with MPN without thrombosis, 50 patients with deep vein thrombosis without MPNs, and 50 healthy blood donors were evaluated. Complete blood count, ADAMTS13, VWF, MV, and FVIII:C in plasma were measured in all the subjects. The JAK-2 mutation was found in 94% of the patients with SVT, but none were triple-negative for genetic mutations (JAK2 V617F, CALR, MPL, and exon 12). Compared to the normal subjects, in all the MPN patients (with or without SVT), the levels of ADAMTS13 were found to be significantly lower (p < 0.001) and the MV concentrations were significantly higher (p < 0.001). Among the MPN patients, the VWF and FVIII:C levels were significantly higher in the patients with SVT than those without thrombosis (p = 0.007 and p = 0.04, respectively). Splenomegaly was present in 78% of MPN patients with SVT and in 30% of those without SVT (p < 0.001). The ADAMTS13/VWF ratio was reduced in all the patients, but not in the healthy blood donors (p < 0.001). The significant increase in circulating MV, VWF, and FVIII:C in the MPN patients and in the patients with thrombosis supports the role of endothelium damage in promoting thrombotic events. In particular, a significant increase in VWF and FVIII:C levels was found in the MPN patients with SVT.

Bibliometric analysis of worldwide research on Polycythemia Vera in the 21st century.

Polycythemia vera (PV) is a myeloproliferative tumor with low incidence and complex symptoms, affecting patients' quality of life and shortening their life span. Since the beginning of the 21st century, there has been an update but a need for uniform consensus regarding diagnosing and treating PV. With the continued interest of researchers in this field, a bibliometric study of PV is necessary. This paper aims to analyze articles on PV through bibliometric software to provide collaborative information and new ideas for researchers in this field. We collected PV-related publications in the Web of Science Core Collection database from 2000 to 2023. The included literature was analyzed using Citespace (6.2.R2), VOSviewer (1.6.19), and Bibliometrix. The study included country/region, institution, authors, journals, keywords, and references, and a visual knowledge network diagram was constructed. Microsoft Excel 2013 was also used for statistical analysis. A total of 1,093 articles were eventually included. The number of PV-related publications has steadily increased from 2000 to the present, with great potential for future growth. The US and US institutions have contributed more to this field, with the US ranking first in the number of publications, total citations, and centrality. Alessandro M. Vannucchi is the most published author. Tefferi, Ayalew is the most cited author. And BLOOD has the most publications, topping the list of the eleven high-productivity core source journals. The most cited article was "Acquired mutation of the tyrosine kinase JAK2 in human myeloproliferative disorders" (Baxter, EJ, 2005). By examining the keywords, we found that the diagnosis and typing of true erythrocytosis, the use of ruxolitinib, and the tyrosine kinase JAK2 are the research hotspots in the field; genetic and molecular research in the field of true erythrocytosis is a cutting-edge topic in the field; and risk factors for true erythrocytosis is a cutting-edge hotspot issue in the field. The fruitful research in this century has laid the foundation for developing the field of PV. The information in this article will provide researchers with current hotspots and future potential in the discipline, helping the field achieve more extraordinary breakthroughs. Currently, research should focus on increasing global multicenter collaborative research in diagnosis and treatment to develop scientifically recognized diagnostic and treatment protocols and new clinical drug research. Our proposed model of global innovation collaboration will provide strong support for future research.

Essential thrombocythaemia: A contemporary approach with new drugs on the horizon.

Essential thrombocythaemia (ET) is a myeloproliferative neoplasm characterized by an increased risk of vascular complications and a tendency to progress to myelofibrosis and acute leukaemia. ET patients have traditionally been stratified into two thrombosis risk categories based on age older than 60 years and a history of thrombosis. More recently, the revised IPSET-thrombosis scoring system, which accounts for the increased risk linked to the JAK2 mutation, has been incorporated into most expert recommendations. However, there is increasing evidence that the term ET encompasses different genomic entities, each with a distinct clinical course and prognosis. Moreover, the effectiveness and toxicity of cytoreductive and anti-platelet treatments differ depending on the molecular genotype. While anti-platelets and conventional cytoreductive agents, mainly hydroxycarbamide (hydroxyurea), anagrelide and pegylated interferon, remain the cornerstone of treatment, recent research has shed light on the effectiveness of novel therapies that may help improve outcomes. This comprehensive review focuses on the evolving landscape of treatment strategies in ET, with an emphasis on the role of molecular profiling in guiding therapeutic decisions. Besides evidence-based management according to revised IPSET-thrombosis stratification, we also provide specific observations for those patients with CALR-, MPL-mutated and triple-negative ET, as well as cases with high-risk mutations.

Diagnostic Approaches to Investigate JAK2-Unmutated Erythrocytosis Based on a Single Tertiary Center Experience.

Erythrocytosis is attributed to various clinical and molecular factors. Many cases of JAK2-unmutated erythrocytosis remain undiagnosed. We investigated the characteristics and causes of JAK2-unmutated erythrocytosis. We assessed the clinical and laboratory results of patients with erythrocytosis without JAK2 mutations and performed targeted next-generation sequencing (NGS) panels for somatic and germline mutations. In total, 117 patients with JAK2-unmutated erythrocytosis were included. The median hemoglobin and hematocrit levels were 17.9 g/dL and 53.4%, respectively. Erythropoietin levels were not below the reference range. Thrombotic events were reported in 17 patients (14.5%). Among JAK2-unmutated patients, 44 had undergone targeted panel sequencing consisting of myeloid neoplasm-related genes, and 16 had one or more reportable variants in ASXL1 (5/44), TET2, CALR, FLT3, and SH2B3 (2/44). Additional testing for germline causes revealed eight variants in seven genes in eight patients, including NF1, BPGM, EPAS1, PIEZO1, RHAG, SH2B3, and VHL genes. One NF1 pathogenic, one BPGM likely pathogenic, and six variants of undetermined significance were detected. Somatic and germline mutations were identified in 36.4% and 33.3 % of the JAK2-unmutated group; most variants had unknown clinical significance. Not all genetic causes have been identified; comprehensive diagnostic approaches are crucial for identifying the cause of erythrocytosis.

Two Novel Genetic Variants Involved in the Oxygen Sensing Pathway in JAK2-unmutated Erythrocytosis.

JAK2-unmutated erythrocytosis or non-polycythemia vera erythrocytosis is a rare condition comprising both acquired and hereditary forms. Although acquired erythrocytosis has been well-studied, hereditary erythrocytosis remains poorly studied. Genetic alterations associated with hereditary erythrocytosis include mutations in erythropoietin receptor and erythropoietin (EPO), altered oxygen affinity mutations, and variants associated with the oxygen-sensing pathway. We established a molecular diagnostic approach based on these genes and retrospectively evaluated. Peripheral blood from 56 erythrocytosis patients, lacking JAK2 mutation, were screened for oxygen-sensing pathway abnormalities. Two novel mutations were identified in the EGLN1 gene: NM_022051.2:c.712G > C (p.Gly238Arg) and NM_022051.2:c.122A > C (p.Tyr41Ser) in two patients separately. Notably, both reported heterozygous mutations were absent in the population database. Predictions using multiple computer software indicated that these two missense mutations were harmful and induced a highly conserved amino acid change in EGLN1. Patients with the two mutations exhibited normal serum EPO levels and high hemoglobin and hematocrit levels. Additionally, three other variants of genes were identified in the oxygen-sensing pathway, including endothelial PAS domain protein 1 (EPAS1) rs184760160(2/56), and EGLN1 rs186996510(2/56), rs555121182(2/56). These variants were categorized as benign or likely benign. Our findings provide a framework for etiological research and highlight the importance of screening for genetic mutations associated with erythrocytosis in clinical practice.

Clinical laboratory characteristics and gene mutation spectrum of Ph-negative MPN patients with atypical variants of JAK2, MPL, or CALR.

To evaluate the incidence, clinical laboratory characteristics, and gene mutation spectrum of Ph-negative MPN patients with atypical variants of JAK2, MPL, or CALR. We collected a total of 359 Ph-negative MPN patients with classical mutations in driver genes JAK2, MPL, or CALR, and divided them into two groups based on whether they had additional atypical variants of driver genes JAK2, MPL, or CALR: 304 patients without atypical variants of driver genes and 55 patients with atypical variants of driver genes. We analyzed the relevant characteristics of these patients. This study included 359 patients with Ph-negative MPNs with JAK2, MPL, or CALR classical mutations and found that 55 (15%) patients had atypical variants of JAK2, MPL, or CALR. Among them, 28 cases (51%) were male, and 27 (49%) were female, with a median age of 64 years (range, 21-83). The age of ET patients with atypical variants was higher than that of ET patients without atypical variants [70 (28-80) vs. 61 (19-82), p = 0.03]. The incidence of classical MPL mutations in ET patients with atypical variants was higher than in ET patients without atypical variants [13.3% (2/15) vs. 0% (0/95), p = 0.02]. The number of gene mutations in patients with atypical variants of driver genes PV, ET, and Overt-PMF is more than in patients without atypical variants of PV, ET, and Overt-PMF [PV: 3 (2-6) vs. 2 (1-7), p < 0.001; ET: 4 (2-8) vs. 2 (1-7), p < 0.05; Overt-PMF: 5 (2-9) vs. 3 (1-8), p < 0.001]. The incidence of SH2B3 and ASXL1 mutations were higher in MPN patients with atypical variants than in those without atypical variants (SH2B3: 16% vs. 6%, p < 0.01; ASXL1: 24% vs. 13%, p < 0.05). These data indicate that classical mutations of JAK2, MPL, and CALR may not be completely mutually exclusive with atypical variants of JAK2, MPL, and CALR. In this study, 30 different atypical variants of JAK2, MPL, and CALR were identified, JAK2 G127D being the most common (42%, 23/55). Interestingly, JAK2 G127D only co-occurred with JAK2V617F mutation. The incidence of atypical variants of JAK2 in Ph-negative MPNs was much higher than that of the atypical variants of MPL and CALR. The significance of these atypical variants will be further studied in the future.

Broad Next-Generation Integrated Sequencing of Myelofibrosis Identifies Disease-Specific and Age-Related Genomic Alterations.

Myeloproliferative neoplasms (MPN) are characterized by the overproduction of differentiated myeloid cells. Mutations in JAK2, CALR, and MPL are considered drivers of Bcr-Abl-ve MPN, including essential thrombocythemia (ET), polycythemia vera (PV), prefibrotic primary myelofibrosis (prePMF), and overt myelofibrosis (MF). However, how these driver mutations lead to phenotypically distinct and/or overlapping diseases is unclear. To compare the genetic landscape of MF to ET/PV/PrePMF, we sequenced 1,711 genes for mutations along with whole transcriptome RNA sequencing of 137 patients with MPN. In addition to driver mutations, 234 and 74 genes were found to be mutated in overt MF (N = 106) and ET/PV/PrePMF (N = 31), respectively. Overt MF had more mutations compared with ET/PV/prePMF (5 vs. 4 per subject, P = 0.006). Genes frequently mutated in MF included high-risk genes (ASXL1, SRSF2, EZH2, IDH1/2, and U2AF1) and Ras pathway genes. Mutations in NRAS, KRAS, SRSF2, EZH2, IDH2, and NF1 were exclusive to MF. Advancing age, higher DIPSS, and poor overall survival (OS) correlated with increased variants in MF. Ras mutations were associated with higher leukocytes and platelets and poor OS. The comparison of gene expression showed upregulation of proliferation and inflammatory pathways in MF. Notably, ADGRL4, DNASE1L3, PLEKHGB4, HSPG2, MAMDC2, and DPYSL3 were differentially expressed in hematopoietic stem and differentiated cells. Our results illustrate that evolution of MF from ET/PV/PrePMF likely advances with age, accumulation of mutations, and activation of proliferative pathways. The genes and pathways identified by integrated genomics approach provide insight into disease transformation and progression and potential targets for therapeutic intervention.

Prevalence and clinicopathological features of driver gene mutations profile in BCR: ABL1 negative classical myeloproliferative neoplasm-A single-center study from North India.

Recurrent somatic mutations in the JAK2, CALR, and the MPL genes are noted in BCR: ABL1 negative classic myeloproliferative neoplasms (MPN) that includes polycythemia vera (PV), essential thrombocytosis (ET), and primary myelofibrosis (PMF). Mutation profile and clinical features of MPN cases diagnosed at a tertiary care center in North India are being described. JAK2V617F mutation was screened using ARMS PCR, and CALR mutation was screened using allele-specific PCR followed by fragment analysis. MPL and JAK2 Exon 12 mutations were screened by Sanger sequencing. Some of the samples were also screened using commercial kits based on single-plex RT PCR. A total of 378 cases (including 124 PV, 121 ET, and 133 PMF cases) were screened over 6.5 years. JAK2V617F mutation was noted in 90.3%, 61.1%, and 69.2% of cases of PV, ET, and PMF, respectively. In PV, JAK2V617F wild-type cases were associated with a significantly lower age (44 yrs vs 54 yrs; P = 0.001), lower TLC (6.3 vs 16.9; P = 0.001), and a lower platelet count (188 × 109/L vs 435 × 109/L; P = 0.009) as compared to the JAK2V617F mutated cases. CALR and MPL mutations were noted in 17.4% and 12% and 0.8% and 5.3% of ET and PMF cases, respectively. Type 1 CALR mutations were commoner in both ET and PMF. The triple negative cases constituted 20.7% and 13.5% cases of ET and PMF, respectively. In ET, the triple negative cases were found to have a significantly lower median age of presentation (42 yrs vs 52 yrs; P = 0.001), lower median TLC (10.2 × 109/L vs 13.2 × 109/L; P = 0.024), and a higher median platelet count (1238 × 109/L vs 906 × 109/L; P = 0.001) as compared to driver genes mutated cases. In PMF, the triple negative cases were found to have a significantly lower hemoglobin level (7.9 g/dl vs 11.0 gl/dl; P = 0.001) and a significant female preponderance (P = 0.05) as compared to the mutated cases. CALR mutations were found to have a significantly lower median age (43 yrs vs 56 yrs; P = 0.001) and lower hemoglobin (9.6 g/dl vs 11.3 g/dl) as compared to the JAK2 mutations. Our data on the driver gene mutational profile of BCR: ABL1 negative MPN is one of the largest patient cohorts. The prevalence and clinicopathological features corroborate with that of other Asian studies.

Clinicopathological and molecular genetic alterations in monomorphic–epitheliotropic intestinal T-cell lymphoma of the small intestine

BackgroundSmall intestinal monomorphic–epitheliotropic intestinal T-cell lymphoma (MEITL) is a rare aggressive T-cell lymphoma originating in the gastrointestinal tract. This study aimed to investigate the clinicopathological features, immunophenotypes, and molecular genetic changes of MEITL.MethodsThe clinicopathological data for three patients with surgically resected MEITL of the small intestine were collected. Next, immunohistochemical labeling, Epstein–Barr virus (EBV) in situ hybridization, assessment of clonal rearrangement of T-cell receptor (TCR) genes, and next-generation sequencing (NGS) were performed.ResultsOf the three patients, two were male and one was female, with ages of 61, 67, and 73 years, respectively. Clinical manifestations were predominantly abdominal pain and distension. Histopathology revealed infiltrative growth of small-to-medium-sized lymphocytes with a consistent morphology between the intestinal walls, accompanied by an obvious pro-epithelial phenomenon. The expression of CD3, CD8, CD43, CD56, TIA-1, CD103, H3K36me3, and Bcl-2 was detected, and the Ki-67 proliferation index ranged from 50% to 80%. All three patients tested negative for EBER. However, monoclonal rearrangement of the TCR gene was detected in them. NGS testing showed a JAK3 mutation in all three cases. Further, STAT5B, SETD2, and TP53 mutations were each observed in two cases, and a BCOR mutation was found in one case. All patients were treated with chemotherapy after surgery. Two patients died 7 and 15 month post-operation, and one patient survived for 5 months of follow-up.ConclusionsOur findings demonstrate that mutations in JAK3 and STAT5B of the JAK/STAT pathway and inactivation of the oncogene SETD2 markedly contribute to the lymphomagenesis of MEITL.

Abstract 3852: Comprehensive genomic profiling of recurrent or metastatic head and neck cancer presenting with combined positive score 90 or more

Abstract Background. Biomarkers that predict response to immune checkpoint inhibitor (ICI) in recurrent metastatic squamous cell carcinoma of the head and neck (RMHNSCC) are not well known. Previously, we have found that Combined positive score (CPS) ≥90 and albumin &amp;gt;3.5 respond well to ICI treatment in patients with RMHNSCC treated with ICI irrespective of addition of chemotherapy. In the present study, we investigated whether RMHNSCC with CPS ≥90 has a characteristic genomic mutational profile. Methods. CPS measurements were performed on a single tumor specimen at the time of diagnosis of RMHNSCC, as approved by Japanese health insurance. Tumor specimens were obtained from the primary tumor as much as possible, and sections that best reflected anti-tumor immunity were decided by a pathologist. We retrospectively reviewed the results obtained from comprehensive genomic profiling (CGP) testing of RMHNSCC cases with CPS ≥90 who were treated by ICI experienced at our institution. Results. There were 117 eligible RMHNSCC cases. The number of primary lesions were oral cavity in 28 cases (23.9%), nasopharynx in 10 cases (8.5%), oropharynx in 21 cases (17.9%), hypopharynx in 33 cases (28.2%), and others in 18 cases (15.4%). Of 117 patients, 28 patients (23.9%) had a CPS ≥90. Of the 28 cases, the number of primary lesions were oral cavity in 12 cases (42.9%), nasopharynx in 4 cases (14.3%), oropharynx in 0 cases (0%), hypopharynx in 8 cases (28.6%), and others in 3 cases (10.7%). When ICI was administered, CPS ≥90 had a statistically significantly better prognosis than CPS &amp;lt;90 for OS and PFS. Of the 28 cases with CPS ≥90, CGP test was performed in 6 cases. The primary lesions in the 6 cases consisted of 3 oral cavity, 2 nasopharynx, 1 hypopharynx, and 1 maxillary sinus. All three oral primary cases had co-mutations in the TERT promoter and HRAS. Two of the nasopharyngeal primary cases had mutations in JAK3 and STAT, respectively. One of the hypopharyngeal primary cases had mutations in FGFR3. Conclusion. RMHNSCC with CPS ≥90 had unique mutations that could account the enhanced PD-L1 expression, such as TERT/HRAS co-mutation, JAK-STAT pathway mutation, and FGFR pathway mutation. The above findings may be useful for predicting the efficacy of ICI for RMHNSCC. Citation Format: Yuki Saito, Kage Hidenori, Kenya Kobayashi, Osamu Fukuoka, Koji Yamamura, Aya Shinozaki-Ushiku, Katsutoshi Oda, Kenji Kondo. Comprehensive genomic profiling of recurrent or metastatic head and neck cancer presenting with combined positive score 90 or more [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 3852.

Abstract 2666: Genetic ablation of B2M leads to resistance to PD-1/PD-L1 blockade in vivo

Abstract Immune checkpoint inhibitors (ICIs) has revolutionized the treatment landscape of various cancers by reinvigorating the exhausted T cells in patients. However, the therapeutic efficacy is largely confined due to the primary or acquired resistance to anti-PD-1 (L1) therapy in many patients. Recently, the mechanisms of resistance to ICIs has been extensively elucidated from different aspects and emerging sequencing data from clinical samples has pointed to IFN-γ signaling defects and antigen presentation loss in patients who are resistant to PD-1(L1) blockade. The loss-of-function mutations in JAK1 and JAK2 results in lack of response to IFN-γ signaling and incapacity to upregulate PD-L1 and MHC-I, which subsequently leads to noninflammatory TMEs and resistance to anti-PD-1/PD-L1. The loss-of-function of B2M is likely a common resistance mechanism that the intratumoral cytotoxic CD8+ T cells are failed to be boosted owing to antigen presentation loss. In order to obtain higher clinical benefits in various cancers, it’s appealing and urgent to develop mechanism-based strategies to overcome resistance to ICI-based immunotherapy. To this end, we developed a genetically acquired resistant tumor model with B2M mutations in syngenic MC38 tumor cells using CRISPR/Cas9 technology, which is ‘hot’ tumor to PD-1/PD-L1 blockade. The expression of B2M was detected by western blotting and flow cytometry. Mouse B2M-knockout MC38 tumors became resistant to PD-1/PD-L1 blockade in vivo. Notably, we found a remarkable increase of CD8+ T cell infiltration in B2m-KO MC38 tumors in comparison to parental MC38 tumors upon anti-PD-1 treatment, which further explains that antigen presentation loss results in inactivation of cytotoxic CD8+ T cells within the tumor microenvironments (TMEs), subsequently leading to resistance and poor survival to ICI therapy.In summary, our data consistently indicated the importance of MHC-I expression in T cell activation in the TMEs and the possibility to dig out the pathway involved in MHC-I expression independent of IFN-γ signaling by CRISPR-based screening to overcome MHC-I deficiency-induced resistance in the future. In addition, it’s possible to leverage the cytotoxic NK cells and CD4+ T cells in antitumor immunity against MHC-II+ tumors even with the loss of MHC-I molecules. For example, high dose of IL-2RB-biased IL-2 agonist preferentially binding to the dimeric IL-2R can stimulate Teff and NK cells independent of immune checkpoint expression. Likewise, cytokine modified anti-PD-1 fusion formulation like anti-PD-1-IL-2 mutein and anti-PD-1-IL-15 mutein are promising to overcome the resistance. Furthermore, it has been suggested that the resistance due to genetic mutations of MHC-I could be overcome by combining NF-B targeted therapies. Citation Format: Yanlei Zhang, Hechun Ma, Boang Han, Yi Li, Ping Yang, Zhen Li, Dongxiao Feng, Lei Ci, Ruilin Sun, Daniel X. He. Genetic ablation of B2M leads to resistance to PD-1/PD-L1 blockade in vivo [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 2666.

Abstract 2801: Identifying gut microbial determinants of clonal hematopoiesis of indeterminate potential (CHIP) in immunotherapy treated melanoma patients

Abstract INTRO: Clonal hematopoiesis (CH) of indeterminate potential (CHIP) is associated with poor outcomes in those with non-hematologic cancers. CH mutated macrophages and neutrophils have increased capacity to home to peripheral tissues, driving local inflammation; they are also implicated in immunotherapy related toxicity. The relationship between CH and the microbiome in those treated with immunotherapy is not well understood. RESULTS: 35 patients with stage IV melanoma treated with upfront immunotherapy; treatment and cohort characteristics are below (Table 1). We performed error corrected duplex sequencing on peripheral blood mononuclear cells using a panel previously validated for CH mutations. With a cutoff of 0.5% variant allele frequency (VAF), among 10 CHIP positive patients, we found mutations in TET2 (8/10), DNMT3A (7/10), PPM1D (2/10), and JAK2 (1/10). There was no difference in either survival or response based on CHIP status (Log-Rank Chi-Square p=0.44); however, CHIP positivity was associated with greater microbiome richness as measured by alpha diversity (p=0.0012 Shannon diversity) and distinct structural/compositional diversity vs CHIP negative patients as measured by beta diversity (p=0.032, R Squared= 0.045). We inferred KEGG pathway activity from whole genome sequencing and identified that CHIP positive patients were enriched for exopolysaccharide biosynthesis while CHIP negative patients had higher expression of nucleotide sugars biosynthesis and amino acid metabolism pathways. DISCUSSION: In patients treated with immunotherapy for melanoma, microbiome diversity signatures correlate with presence of CHIP. The analysis suggests that there are distinct taxonomic and functional features defining CHIP positivity. The effect of these cells in the tumor microenvironment and their role in immunotherapy response requires further exploration. Citation Format: Eleanor A. Fallon, Samuel Urrutia, Reed Ayabe, Manoj Chelvanambi, Ashish Damania, Sarah Johnson, Tomoyuki Tanaka, Zongrui Li, Yongwoo David Seo, Samuel Cass, Matthew C. Wong, Nadim Ajami, Jennifer Wargo, Koichi Takahashi. Identifying gut microbial determinants of clonal hematopoiesis of indeterminate potential (CHIP) in immunotherapy treated melanoma patients [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 2801.

Abstract 260: Depletion of Ezh2 in the intestinal adenoma induced by JAK2V617F mutation leads to the malignant neoplasm

Abstract Background The increased JAK2 and EZH2 plays a critical role in the colorectal or colon cancer (CRC) progression. Targeting aberrant JAK2 expression caused by JAK2 gain-of-function (GOF) mutation, JAK2V617F and deregulated EZH2 kinase activity, JAK2 and/or EZH2 inhibitors have been used to treat the advanced CRCs. However, it is unclear whether the aberrant JAK2 can directly induce CRC or intestinal epithelial (IEC) malignancy. We hypothesize that the overexpressed JAK2 driven by JAK2V617F GOF mutation increases IEC neoplasia in which depletion of EZH2 can lead to IEC malignant neoplasm. Materials and Methods Colorectal samples were collected from 20 cases of CRC patients. Immunohistochemistry staining (IH), confocal immunofluorescence staining (IF) and bulk RNAseq were used to determine LGR5, Ki67, JAK2, EZH2, mutant β-catenin and JAK2V617F GOF mutation. Crypt-derived organoids or tumoroids were used to determine the JAK2 and EZH2 in the proliferative LGR5 cells (Ki67hiLGR5+) and were treated with JAK2 and/or EZH2 inhibitors. The mice with JAK2 and/or EZH2 deficiency in IECs were generated by crossing VilCreER mice, floxed-Jak2 and/or floxed-Ezh2 mice to determine the intestinal and colonic neoplasia. Lgr5, Ki67, Cdx2 Jak2, Ezh2, and mutant β-catenin IH or IF, organoids culture and peritoneal xenograft were used to determine the malignant neoplasm. The JAK2V617F-transfected HT29 or Caco-2 cells were used to determine the migration induced by JAK2V617F GOF mutation, then treated with EZH2 inhibitors to determine the effects of EZH2 inhibition on JAK2V617F GOF mutation-induced migration. The spheres were formed with Caco-cells with JAK2V617F GOF mutation and were used to observe the effects of JAK2V617F GOF mutation on IEC neoplasia formation. Results JAK2 and/or EZH2 overexpression are positively correlated with the probability of CRC initiation. JAK2 and EZH2 are highly expressed in the CRC tumoroids. Inhibition of EZH2 increases the CRC tumoroids growth and spheroid formation, and reduces budding numbers while reducing the proliferation of organoids from healthy crypts. Jak2 over-expression in IECs increases intestinal microadenoma, and depletion of EZH2 in the adenoma increases mutant β-catenin and severity of intestinal adenoma, suggesting that depletion of EZH2 enhances the malignancy of overexpressed Jak2-derived IEC neoplasia. Consistently, JAK2V617F GOF mutation increases HT29 or Caco-2 cell migration. Conclusion JAK2V617F GOF mutation can drive IEC neoplastic proliferation and adenoma, depletion of EZH2 in the adenoma leads to IEC malignant neoplasm. Our research suggests that loss of Ezh2 may synergistically cooperate with the Jak2V617F mutation in the pathogenesis of IEC malignant neoplasm. Citation Format: Nardana Esmaeili, Ahmed Bakheet, Wen Gao, Haifeng Li, Dan Cai, Xiaonan Han. Depletion of Ezh2 in the intestinal adenoma induced by JAK2V617F mutation leads to the malignant neoplasm [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 260.

Activating mutations in JAK2 and CALR differentially affect intracellular calcium flux in store operated calcium entry

BackgroundCalcium (Ca2+) signaling regulates various vital cellular functions, including integrin activation and cell migration. Store-operated calcium entry (SOCE) via calcium release-activated calcium (CRAC) channels represents a major pathway for Ca2+ influx from the extracellular space in multiple cell types. The impact of JAK2-V617F and CALR mutations which are disease initiating in myeloproliferative neoplasms (MPN) on SOCE, calcium flux from the endoplasmic reticulum (ER) to the cytosol, and related key signaling pathways in the presence or absence of erythropoietin (EPO) or thrombopoietin (TPO) is poorly understood. Thus, this study aimed to elucidate the effects of these mutations on the aforementioned calcium dynamics, in cellular models of MPN.MethodsIntracellular Ca2+ levels were measured over a time frame of 0–1080 s in Fura-2 AM labeled myeloid progenitor 32D cells expressing various mutations (JAK2-WT/EpoR, JAK2-V617F/EpoR; CALR-WT/MPL, CALR-ins5/MPL, and del52/MPL). Basal Ca2+ concentrations were assessed from 0–108 s. Subsequently, cells were stimulated with EPO/TPO in Ca2+-free Ringer solution, measuring Ca2+ levels from 109–594 s (store depletion). Then, 2 mM of Ca2+ buffer resembling physiological concentrations was added to induce SOCE, and Ca2+ levels were measured from 595–1080 s. Fura-2 AM emission ratios (F340/380) were used to quantify the integrated Ca2+ signal. Statistical significance was assessed by unpaired Student's t-test or Mann–Whitney-U-test, one-way or two-way ANOVA followed by Tukey's multiple comparison test.ResultsFollowing EPO stimulation, the area under the curve (AUC) representing SOCE significantly increased in 32D-JAK2-V617F cells compared to JAK2-WT cells. In TPO-stimulated CALR cells, we observed elevated Ca2+ levels during store depletion and SOCE in CALR-WT cells compared to CALR-ins5 and del52 cells. Notably, upon stimulation, key components of the Ca2+ signaling pathways, including PLCγ-1 and IP3R, were differentially affected in these cell lines. Hyper-activated PLCγ-1 and IP3R were observed in JAK2-V617F but not in CALR mutated cells. Inhibition of calcium regulatory mechanisms suppressed cellular growth and induced apoptosis in JAK2-V617F cells.ConclusionsThis report highlights the impact of JAK2 and CALR mutations on Ca2+ flux (store depletion and SOCE) in response to stimulation with EPO and TPO. The study shows that the JAK2-V617F mutation strongly alters the regulatory mechanism of EpoR/JAK2-dependent intracellular calcium balance, affecting baseline calcium levels, EPO-induced calcium entry, and PLCγ-1 signaling pathways. Our results reveal an important role of calcium flux in the homeostasis of JAK2-V617F positive cells.

Loss of Dnmt3a increases self-renewal and resistance to pegIFN-α in JAK2-V617F–positive myeloproliferative neoplasms

AbstractPegylated interferon alfa (pegIFN-α) can induce molecular remissions in patients with JAK2-V617F–positive myeloproliferative neoplasms (MPNs) by targeting long-term hematopoietic stem cells (LT-HSCs). Additional somatic mutations in genes regulating LT-HSC self-renewal, such as DNMT3A, have been reported to have poorer responses to pegIFN-α. We investigated whether DNMT3A loss leads to alterations in JAK2-V617F LT-HSC functions conferring resistance to pegIFN-α treatment in a mouse model of MPN and in hematopoietic progenitors from patients with MPN. Long-term treatment with pegIFN-α normalized blood parameters and reduced splenomegaly and JAK2-V617F chimerism in single-mutant JAK2-V617F (VF) mice. However, pegIFN-α in VF;Dnmt3aΔ/Δ (VF;DmΔ/Δ) mice worsened splenomegaly and failed to reduce JAK2-V617F chimerism. Furthermore, LT-HSCs from VF;DmΔ/Δ mice compared with VF were less prone to accumulate DNA damage and exit dormancy upon pegIFN-α treatment. RNA sequencing showed that IFN-α induced stronger upregulation of inflammatory pathways in LT-HSCs from VF;DmΔ/Δ than from VF mice, indicating that the resistance of VF;DmΔ/Δ LT-HSC was not due to failure in IFN-α signaling. Transplantations of bone marrow from pegIFN-α–treated VF;DmΔ/Δ mice gave rise to more aggressive disease in secondary and tertiary recipients. Liquid cultures of hematopoietic progenitors from patients with MPN with JAK2-V617F and DNMT3A mutation showed increased percentages of JAK2-V617F–positive colonies upon IFN-α exposure, whereas in patients with JAK2-V617F alone, the percentages of JAK2-V617F–positive colonies decreased or remained unchanged. PegIFN-α combined with 5-azacytidine only partially overcame resistance in VF;DmΔ/Δ mice. However, this combination strongly decreased the JAK2-mutant allele burden in mice carrying VF mutation only, showing potential to inflict substantial damage preferentially to the JAK2-mutant clone.

A Review About the Assessment of the Bleeding and Thrombosis Risk for Patients With Myeloproliferative Neoplasms Scheduled for Surgery.

Myeloproliferative neoplasms (MPNs) present a unique challenge in surgical management due to their inherent predisposition to both bleeding and thrombosis. MPNs are a heterogenous group of acquired clonal conditions. The three classic MPNs are essential thrombocythemia (ET), myelofibrosis (PMF), and polycythemia vera (PV). All subtypes of MPN are associated with both thrombotic and bleeding complications. There are four risk categories for thrombosis in MPN patients: age, thrombosis history, and JAK-2 mutation. They are further classified as very low, low, intermediate, and high risk. The genetic landscape of MPN is fascinating and complex like all myeloid disorders. Bleeding risk can be assessed through leukocytosis, thrombocytosis, acquired von Willebrand syndrome (AVWS), and a previous history of bleeding in a patient.Risk assessment and perioperative management are important aspects of improving the quality of life and preventing complications in surgeries. Preoperative management includes a risk assessment of venous thromboembolism, use of appropriate pharmacological treatment, platelet count control, and correction and cardiovascular risk factors. This review summarizes the assessment of bleeding and thrombosis risk for patients with MPNs scheduled for surgery. Furthermore, this review discusses various tools that can be used to identify MPN patients at risk of thrombosis prior to surgery.

Abstract B102: Mutational and copy number-based ctDNA profiles mirror high-grade serous cancer tumors and enable detection of genetic changes appearing at recurrence

Abstract Circulating tumor DNA (ctDNA) is the cancer-derived fraction of extracellular DNA fragments present in the bloodstream as cell-free DNA (cfDNA). Consequently, ctDNA harbors the distinct genomic information specific to the cancer from which it derives. Therefore, ctDNA from liquid biopsies provides a non-invasive, universally available alternative to traditional tumor biopsies. ctDNA amount may provide insight into tumor burden, as its concentration is typically highest during diagnosis and relapse. The non-invasive nature of this method facilitates frequent monitoring, enabling longitudinal tracking of the disease's trajectory and response to treatments. By focusing on the key genomic changes, either short mutations or copy number aberrations (CNA), liquid biopsy allows the investigation of cancer progression and evolution over time, providing invaluable insight into the behavior and adaptability of the cancer. We collected 152 longitudinal plasma samples and 92 fresh tissue samples from 29 patients enrolled in the DECIDER cohort (NCT04846933), after a diagnosis of high-grade serous carcinoma (HGSC), the most common and deadliest histological subtype of ovarian cancer. With ultra-deep targeted sequencing of a gene panel of more than 700 cancer-related genes we were able to comprehensively evaluate the cancer-related genomic changes. The concordance rate between mutations in plasma compared to tumor tissue was 83 % at diagnosis and 90 % at relapse, confirming the reliability of exploiting ctDNA in monitoring genomic alterations. Furthermore, by comparing plasma- and tissue-derived mutations, we demonstrated that comparable levels of ctDNA are released from adnexa, intra-abdominal lesions, and ascites, proposing that a liquid biopsy represents mutations from various locations. Analysis of CNA showed that our approach successfully detected concordant profiles in most plasma samples, even with tumor content as low as 3%. Additionally, highly amplified regions were identified in samples with approximately 1% tumor content. Longitudinal analysis of both mutations and CNA revealed genomic changes in plasma samples at relapse. Twenty-four new exonic mutations were identified in eight patients at relapse; two of these alterations were related to HRD status, supporting PARP-inhibitors as a valid treatment option. Furthermore, mutations in FGFR3, JAK2, FLT3 and CDKN2A could be investigated as target indications for extended use of currently available therapies. Eleven patients had high tumor content in their plasma samples at the time of relapse. We detected altered CNA profiles in seven of these eleven patients, so that five patients harbored only a few novel focal amplifications or losses, while two patients showed significant changes in their copy-number profile during the therapy. In conclusion, our study identified recurrence-specific genomic aberrations, proposing that ctDNA more accurately represents the metastatic tumor and provides possibilities for personalized therapy options. Citation Format: Giovanni Marchi, Mai T.N. Nguyen, Anna Rajavuori, Taru Muranen, Kaisa Huhtinen, Sinikka Oksa, Sakari Hietanen, Johanna Hynninen, Jaana Oikkonen, Sampsa Hautaniemi. Mutational and copy number-based ctDNA profiles mirror high-grade serous cancer tumors and enable detection of genetic changes appearing at recurrence [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr B102.