Recurrent Mutations Research Articles

Olutasidenib: a novel mutant IDH1 inhibitor for the treatment of relapsed or refractory acute myeloid leukemia.

Recurrent mutations in isocitrate dehydrogenase 1 (mIDH1) occur in about 7% to 14% of all cases of acute myeloid leukemia (AML). The discovery of targetable mutations in AML, including IDH mutations, expanded the therapeutic landscape of AML and led to the development of targeted agents. Despite significant advances in current treatment options, remission and overall survival rates remain suboptimal. The IDH1 inhibitor, olutasidenib, demonstrated encouraging safety and clinical benefits as monotherapy in patients with relapsed or refractory (R/R) mIDH1-AML. This review outlines the olutasidenib drug profile and summarizes key safety and efficacy data, focusing on the 150 mg twice daily dose from the pivotal registrational cohort of the phase 2 trial that formed the basis for the US Food and Drug Administration approval of olutasidenib in patients with R/R AML with a susceptible IDH1 mutation. Olutasidenib offers patients with R/R mIDH1-AML a new treatment option, with improved complete responses and a longer duration of response than other targeted mIDH1 treatment options. Olutasidenib provided clinical benefit with a manageable safety profile. Additional analyses to further characterize the safety and efficacy of olutasidenib in frontline and R/R settings as monotherapy and as combination therapy are ongoing.

Combined analysis of albumin in situ hybridisation and C reactive protein immunohistochemistry for the diagnosis of intrahepatic cholangiocarcinoma: towards a molecular classification paradigm

AimsIntrahepatic cholangiocarcinoma (iCCA) is a diagnosis of exclusion that can pose a challenge to the pathologist despite thorough clinical workup. Although several immunohistochemical markers have been proposed for iCCA, none...

Clinico-genomic findings, molecular docking, and mutational spectrum in an understudied population with breast cancer patients from KP, Pakistan

In this study, we report the mutational profiles, pathogenicity, and their association with different clinicopathologic and sociogenetic factors in patients with Pashtun ethnicity for the first time. A total of 19 FFPE blocks of invasive ductal carcinoma (IDC) from the Breast Cancer (BC) tissue and 6 normal FFPE blocks were analyzed by whole-exome sequencing (WES). Various somatic and germline mutations were identified in cancer-related genes, i.e., ATM, CHEK2, PALB2, and XRCC2. Among a total of 18 mutations, 14 mutations were somatic and 4 were germline. The ATM gene exhibited the maximum number of mutations (11/18), followed by CHEK2 (3/18), PALB2 (3/18), and XRCC2 (1/18). Except one frameshift deletion, all other 17 mutations were nonsynonymous single-nucleotide variants (SNVs). SIFT prediction revealed 7/18 (38.8%) mutations as deleterious. PolyPhen-2 and MutationTaster identified 5/18 (27.7%) mutations as probably damaging and 10/18 (55.5%) mutations as disease-causing, respectively. Mutations like PALB2 p.Q559R (6/19; 31.5%), XRCC2 p.R188H (5/19; 26.31%), and ATM p.D1853N (4/19; 21.05%) were recurrent mutations and proposed to have a biomarker potential. The protein network prediction was performed using GeneMANIA and STRING. ISPRED-SEQ indicated three interaction site mutations which were further used for molecular dynamic simulation. An average increase in the radius of gyration was observed in all three mutated proteins revealing their perturbed folding behavior. Obtained SNVs were further correlated with various parameters related to the clinicopathological status of the tumors. Three mutation positions (ATMp. D1853N, CHEK2 p.M314I, and PALB2 p.T1029S) were found to be highly conserved. Finally, the wild- and mutant-type proteins were screened for two drugs: elagolix (DrugBank ID: DB11979) and LTS0102038 (a triterpenoid, isolated from the anticancer medicinal plant Fagonia indica). Comparatively, a higher number of interactions were noted for normal ATM with both compounds, as compared to mutants.

Genotype-phenotype association and functional analysis of hnRNPA1 mutations in amyotrophic lateral sclerosis

Background Pathogenic variants in hnRNPA1 have been reported in amyotrophic lateral sclerosis (ALS) patients. However, studies on hnRNPA1 mutant spectrum and pathogenicity of variants were rare. Methods We performed whole exome sequencing of ALS-associated genes and subsequent verification of rare variants in hnRNPA1 in our ALS patients. The hnRNPA1 mutations reported in literature were reviewed and combined with our results to determine the genotype-phenotype relationship. Functional analysis of the novel variant p.G195A was performed in vitro by transfection of mutant hnRNPA1 into 293T cell. Results Among 207 ALS patients recruited, 3 rare hnRNPA1 variants were identified (mutant frequency 1.45%), including two recurrent mutations (p.P340S and p.G283R), and a novel rare variant p.G195A. In combination with previous reports, there are 27 ALS patients with 15 hnRNPA1 mutations identified. Disease onset age was 47.90 ± 1.52 years with predominant limb onset. The p.P340S mutation caused flail arm syndrome (FAS) in two independent families with extended life expectancy. The newly identified p.G195A mutation, lying at the start of the PrLD (“prion-like” domain)/LCD (low-complexity domain), causes local structural changes in 3D protein prediction. Upon sodium arsenite exposure, mutant hnRNPA1 retained in the nucleus but deficit of cytoplasmic G3BP1-positive stress granule clearance was observed. This is different from the p.P340S mutation which caused both cytoplasmic translocation and stress granule formation. No cytoplasmic TDP-43 translocation was observed. Conclusion Mutations in hnRNPA1 are overall minor in ALS patients. The p.P340S mutation is associated with manifestation of FAS. Mutations in LCD of hnRNPA1 cause stress granule misprocessing.

HER2 mutation as an emerging target in advanced breast cancer.

HER2 activating mutations have emerged as oncogenic drivers and therapeutic targets in a variety of human tumors. In breast cancer, these deregulations occur at low frequency, and are mostly detected in HER2-nonamplified, metastatic disease. Preclinical evidence has clarified the role of hotspot mutations in HER2 constitutive activation, defining them as an alternative mechanism to HER2 gene amplification. Furthermore, recent clinical studies have indicated the emergence of newly acquired HER2 deregulations in significant proportions of breast cancer patients who experience disease progression following both endocrine and HER2-targeted therapies. As the involvement of HER2 mutation in therapy resistance may profoundly impact patient outcomes on successive therapies, several clinical trials are currently investigating the efficacy of various HER2-targeted drugs in HER2-mutant breast cancer. In this review, we firstly summarize the structural organization of the HER2 oncogene and its historical impact on breast cancer prognosis and therapeutic advancement. Then, we provide an overview of the frequencies and functional relevance of clinically recurrent HER2 mutations in breast cancer with a special focus on their role in therapeutic resistance. Finally, we provide a collection of the clinical trials that are currently exploring novel therapeutic approaches for this patient subset and discuss the related perspectives and challenges.

Homozygous familial hypercholesterolemia with xanthomas and a recurrent mutation

Homozygous familial hypercholesterolemia with xanthomas and a recurrent mutation

Wright's hierarchical F-statistics.

This Perspective article offers a meditation on FST and other quantities developed by Sewall Wright to describe population structure, defined as any departure from reproduction through random union of gametes. Concepts related to the F-statistics draw from studies of the partitioning of variation, identity coefficients, and diversity measures. Relationships between the first two approaches have recently been clarified and unified. This essay addresses the third pillar of the discussion: Nei's GST and related measures. A hierarchy of probabilities of identity-by-state (IBS) provides a description of the relationships among levels of a structured population with respect to genetic diversity. Explicit expressions for the IBS probabilities are determined for models of structured populations undergoing regular inbreeding and recurrent mutation. Levels of genetic diversity within and between subpopulations reflect mutation as well as migration. Accordingly, indices of population structure are inherently locus-specific, contrary to the intentions of Wright. Some implications of this locus-specificity are explored.

Abstract PO4-26-06: Identifying mutation-independent signaling pathway activation in molecular subtypes of triple negative breast cancers

Abstract Introduction Triple negative breast cancer (TNBC) is an aggressive cancer defined by the absence of estrogen receptors (ER), progesterone receptors (PR), and lack of human epidermal growth factor receptor 2 (HER-2). We previously identified molecular subgroups with distinct mutational, epigenetic, and clinicopathologic signatures. Here, we sought to identify signaling pathways using targeted RNA expression-based pathway analysis. Methods We analyzed 44 TNBC cases diagnosed at NYU Langone Health between March 2011 and April 2018. Samples were compared based on histology, immunohistochemistry, and epigenetics. We assessed mRNA expression levels of pathway-specific target genes with RT-qPCR using the OncoSIGNal pathway profiling assay. Signal transduction pathway analyses were used to measure activity of the estrogen receptor (ER), androgen receptor (AR), phosphoinositide-3-kinase (PI3K), mitogen-activated protein kinase (MAPK), Hedgehog (HH), Notch, and transforming growth factor beta (TGF- β) pathways. Results DNA methylation Cluster 1, which is enriched for apocrine histology and PI3K/Akt mutations, showed no increased activity in PI3K pathway by RNA expression, but showed increase of AR and MAPK signaling, with a single case of increased ER signaling in the absence of ESR1 activating mutations. In contrast, both DNA methylation Cluster 2 (no recurrent mutations) and Cluster 3 (DNA instability cluster) showed upregulation in PI3K pathway in 4/7 (57%) and 11/25 (44%) of cases, respectively. PI3K pathway activation was invariably associated with high Ki-67 >15%, however not all high Ki-67 cases showed high PI3K activity. Invasive ductal carcinoma (IDC) morphology was characterized by a nearly even split between MAPK (13/28, 46%) and PI3K (12/28, 44%), with single HH and TGF- β driven cases. In 5/28 (18%) of IDC we did not identify an upregulated pathway. Discussion We show that RNA expression-based pathway activity and mutational and epigenetic analyses provide complimentary information about the molecular landscape of TNBC. PI3K mutations are early drivers and lead to distinct epigenetic signatures, however they are not associated with increased PI3K pathway activity by RNA expression. In contrast, TNBC without PI3K mutations may show activation of the PI3K pathway in the absence of PI3K/Akt mutations. Our observation suggests that distinct biomarkers may be differently suited to predict response to PI3K inhibitors in TNBC. This may include expanding the number of patients for which PI3K/Akt pathway inhibition might be a therapeutic option, as well as explaining the lack of response in PI3K mutated tumors. Citation Format: Chanel Schroff, Lawrence Lin, Dianne van Strijp, Daniel Roses, Sigi Neerken, Freya Schnabel, Farbod Darvishian, Matija Snuderl. Identifying mutation-independent signaling pathway activation in molecular subtypes of triple negative breast cancers [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-26-06.

Abstract PO5-25-09: rs2242652 POLYMORPHISM OF THE hTERT GENE IN WOMEN WITH BREAST CANCER

Abstract Introduction: Breast cancer is the most common neoplasm in women around the world. There are several risk factors for this cancer: sex, age, body mass index (BMI), hormone therapy, family history, genetic mutations, among several others. The vast majority of breast tumors are characterized as carcinomas and may originate from ducts or lobules. Immunohistochemistry is related to the expressions of the estrogen receptor (ER) and progesterone receptor (PR), as well as the expression of the human epidermal growth factor receptor 2 (HER2), cell proliferation or the absence of any expression from receptors on the tumor membrane. The telomeres protect the chromosomes natural endings from suffering DNA loss. Telomerase is a ribonuclear protein complex (RNA and protein) that neutralizes telomeres' shortening. Recurrent point mutations in the TERT telomerase promoter have been identified in several cancers, and the rs2242652 polymorphism is a single nucleotide change, and has been described as associated with breast cancer risk. Objective: The objective of this study is to analyze the TERT rs2242652 polymorphism in breast cancer women and to test the correlation of such data with the prognosis and various clinical variables. Methods: The study was conducted as an observational clinical study of women with breast cancer. A blood sample was collected from the patient and PCR was performed to extract the DNA and to analyze the telomerase polymorphisms in this population. To ensure a more descriptive analysis, the data was used in the construction of tables and graphs, that were then studied in a qualitative manner. The associations were analyzed through direct correlation tests and were followed by comparisons of categorization groups. Results and discussion: Fifty-four women presented polymorphism of the telomerase hTERT gene rs2242652. They were divided into two groups according to the A or G allele that confer the GA/AA and GG gene variants. It was found that the GA/AA group had a trend towards more aggressive tumors, presenting 33% triple negative and 22% of tumors with HER2 overexpression, different from the GG group: 19% triple negative and 10% HER2 overexpression. More aggressive T4 tumors, were more expressive in the GA/AA gene variant group representing 20% of the patients, whereas in the GG group they represented only 8%. Conclusion: The data found in this study on the telomerase TERT gene polymorphism rs2242652 with breast cancer refers to a tendency found in tumors that have a more severe prognosis, to associate with the gene variant linked to the A allele of this gene, however a larger sample number is required for statistical confirmation. Citation Format: Miriam Alvares, Elisa Mascarenhas, Joao Matos. rs2242652 POLYMORPHISM OF THE hTERT GENE IN WOMEN WITH BREAST CANCER [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-25-09.

Discovery of the Clinical Candidate Sonrotoclax (BGB-11417), a Highly Potent and Selective Inhibitor for Both WT and G101V Mutant Bcl-2.

The approval of venetoclax, a B-cell lymphoma-2 (Bcl-2) selective inhibitor, for the treatment of chronic lymphocytic leukemia demonstrated that the antiapoptotic protein Bcl-2 is a druggable target for B-cell malignancies. However, venetoclax's limited potency cannot produce a strong, durable clinical benefit in other Bcl-2-mediated malignancies (e.g., diffuse large B-cell lymphomas) and multiple recurrent Bcl-2 mutations (e.g., G101V) have been reported to mediate resistance to venetoclax after long-term treatment. Herein, we described novel Bcl-2 inhibitors with increased potency for both wild-type (WT) and mutant Bcl-2. Comprehensive structure optimization led to the clinical candidate BGB-11417 (compound 12e, sonrotoclax), which exhibits strong in vitro and in vivo inhibitory activity against both WT Bcl-2 and the G101V mutant, as well as excellent selectivity over Bcl-xL without obvious cytochrome P450 inhibition. Currently, BGB-11417 is undergoing phase II/III clinical assessments as monotherapy and combination treatment.

Prenatal and neonatal phenotype of Larsen of La Réunion Island syndrome (B4GALT7-linkeropathy)

Larsen of La Réunion Island syndrome (LRS) is an autosomal recessive condition associated with multiple large joint dislocations, clubfeet, severe dwarfism, and distinctive facial features. LRS is caused by a recurrent homozygous variant in B4GALT7 gene with a founder effect in La Réunion population. Proteoglycans (PG) that are a major component of the extracellular matrix, are composed of a core protein connected to a glycosaminoglycans side chain via a tetrasaccharide linker region. B4GALT7 encodes galactosyltransferase I, one of the enzymes involved in the biosynthesis of the linker region. Conditions caused by pathogenic biallelic variants in genes implicated in the synthesis of the tetrasaccharide linker of PG are known as linkeropathies.Prenatal features are rarely described in this group of chondrodysplasias. We present a series of 12 unpublished patients having LRS and describe the perinatal phenotype. All the patients had a prenatal growth restriction with brevity of limbs. The other features revealed by ultrasounds were increased nuchal translucency at 10–12 weeks of gestation (50 %), feet abnormalities (clubfeet or metatarsus varus) (25 %), dislocation affecting at least one large joint (elbow, knee, wrist) (25 %). Bilateral bowing of femora was noted for two fetuses. Fibular hypertrophy was noted for one fetus. Prenatal helical computed tomography (CT) performed in three pregnancies showed additional data such as bowing of the forearm bones, proximal radio-ulnar synostosis, or dislocation of large joints. Prenatal sonographic and helical CT findings led to the prenatal diagnosis of LRS in four patients. We confirm that the neonatal clinical picture of LRS has an important overlap with that reported in patients with B4GALT7 deficiency outside La Réunion Island and other linkeropathies. The core of the phenotypic spectrum combines low birth height, micromelia, hypermobility, dislocation of at least one large joint, facial features with prominent eyes, microstomia, depressed nasal bridge, and midface hypoplasia. Other clinical features include clubfeet (33%), bifid thumb in one patient, and cardiac abnormalities in two patients. Radiological findings include radio-ulnar synostosis (75%), metaphyseal flaring, precocious carpal ossification, and a Swedish key appearance of the proximal femora. Finally, we also report radiological features rarely described in B4GALT7-linkeropathies, including bowing of the femora and fibular hypertrophy. Our results confirm the phenotypic continuum of LRS within linkeropathies with some additional findings, including a high frequency of clubfeet usually described in B3GALT6-linkeropathies, the presence of congenital heart diseases usually described in B3GAT3-linkeropathies, and a high frequency of metaphyseal flaring usually reported in B3GALT6 or XITLT1-linkeropathies.This is the first study that describes the perinatal phenotype in a cohort of patients with LRS. This study can help improve the prenatal diagnosis of the linkeropathies and add this group of conditions to the differential diagnosis of chondrodysplasias with multiple dislocations.In view of the founder effect for LRS in La Réunion Island, this disease should be suspected in fetuses with growth restriction and micromelia. Thus in case of LOH which include B4GALT7 identified in SNP-array, we recommend performing a targeted Sanger sequencing for the recurrent mutation c.808C > T; p. (Arg270Cys).

Syndromic ciliopathy: a taiwanese single-center study

BackgroundSyndromic ciliopathies are a group of congenital disorders characterized by broad clinical and genetic overlap, including obesity, visual problems, skeletal anomalies, mental retardation, and renal diseases. The hallmark of the pathophysiology among these disorders is defective ciliary functions or formation. Many different genes have been implicated in the pathogenesis of these diseases, but some patients still remain unclear about their genotypes.MethodsThe aim of this study was to identify the genetic causes in patients with syndromic ciliopathy. Patients suspected of or meeting clinical diagnostic criteria for any type of syndromic ciliopathy were recruited at a single diagnostic medical center in Southern Taiwan. Whole exome sequencing (WES) was employed to identify their genotypes and elucidate the mutation spectrum in Taiwanese patients with syndromic ciliopathy. Clinical information was collected at the time of patient enrollment.ResultsA total of 14 cases were molecularly diagnosed with syndromic ciliopathy. Among these cases, 10 had Bardet-Biedl syndrome (BBS), comprising eight BBS2 patients and two BBS7 patients. Additionally, two cases were diagnosed with Alström syndrome, one with Oral-facial-digital syndrome type 14, and another with Joubert syndrome type 10. A total of 4 novel variants were identified. A recurrent splice site mutation, BBS2: c.534 + 1G > T, was present in all eight BBS2 patients, suggesting a founder effect. One BBS2 patient with homozygous c.534 + 1G > T mutations carried a third ciliopathic allele, TTC21B: c.264_267dupTAGA, a nonsense mutation resulting in a premature stop codon and protein truncation.ConclusionsWhole exome sequencing (WES) assists in identifying molecular pathogenic variants in ciliopathic patients, as well as the genetic hotspot mutations in specific populations. It should be considered as the first-line genetic testing for heterogeneous disorders characterized by the involvement of multiple genes and diverse clinical manifestations.

Genomic and Transcriptomic Landscape of RET Wild-Type Medullary Thyroid Cancer and Potential Use of Mitogen-Activated Protein Kinase-Targeted Therapy.

About 75% of medullary thyroid cancers (MTCs) are sporadic with 45-70% being driven by a RET mutation. Selpercatinib is an approved treatment for RET-mutated (mutRET) MTC, however, treatments are needed for wild-type RET MTC (wtRET). Genomic alterations and transcriptomic signatures of wtRET MTC may reveal new therapeutic insights. We did a retrospective analysis of MTC samples submitted for DNA/RNA sequencing and PD-L1 expression using IHC at a CLIA/CAP-certified lab. Tumor microenvironment immune cell fractions were estimated using RNA deconvolution (quanTIseq). Transcriptomic signatures of inflammation and MAP kinase pathway activation scores (MPAS) were calculated. Mann-Whitney U, chi-square, and Fisher exact tests were applied (p-values adjusted for multiple comparisons). The 160-patient cohort included 108 mutRET and 52 wtRET MTC samples. wtRET tumors frequently harbored MAPK pathway mutations, including HRAS (42.31%), KRAS (15.7%), NF1 (6.7%), and BRAF (2%) whereas only one MAPK pathway mutation (NF1) was identified among mutRET MTC. Recurrent mutations seen in wtRET MTC included MGA, VHL, APC, STK11, and NFE2L2. Increased transcriptional activation of the MAPK pathway was observed in wtRET patients harboring mutations in MAPK genes. While the frequency of PD-L1 expression was similar in wtRET and mutRET (10.2% vs 7.0%, p=0.531), wtRET tumors were more often TMB-high (7.7% vs 0.0%, p=0.011), and wtRET MTC exhibited higher expression of immune checkpoint genes. We identified molecular alterations and immune-related features that distinguish wtRET from mutRET MTC. While RET mutation drives MTC in the absence of other alterations, we showed that wtRET MTC frequently harbors MAPK pathway mutations. These findings may indicate a potential basis for MAPK-targeted therapy, possibly in combination with oncology immune-oncology agents for selected patients with wtRET MTC.

Chronic neutrophilic leukemia and atypical chronic myeloid leukemia: 2024 update on diagnosis, genetics, risk stratification, and management.

Chronic neutrophilic leukemia (CNL) is a rare BCR::ABL1-negative myeloproliferative neoplasm (MPN) defined by persistent mature neutrophilic leukocytosis and bone marrow granulocyte hyperplasia. Atypical chronic myeloid leukemia (aCML) (myelodysplastic "[MDS]/MPN with neutrophilia" per World Health Organization [WHO]) is a MDS/MPN overlap disorder featuring dysplastic neutrophilia and circulating myeloid precursors. Both manifest with frequent hepatosplenomegaly and less commonly, bleeding, with high rates of leukemic transformation and death. The 2022 revised WHO classification conserved CNL diagnostic criteria of leukocytosis ≥25 × 109/L, neutrophils ≥80% with <10% circulating precursors, absence of dysplasia, and presence of an activating CSF3R mutation. ICC criteria are harmonized with those of other myeloid entities, with a key distinction being lower leukocytosis threshold (≥13 × 109/L) for cases CSF3R-mutated. Criteria for aCML include leukocytosis ≥13 × 109/L, dysgranulopoiesis, circulating myeloid precursors ≥10%, and at least one cytopenia for MDS-thresholds (ICC). In both classifications ASXL1 and SETBP1 (ICC), or SETBP1 ± ETNK1 (WHO) mutations can be used to support the diagnosis. Both diseases show hypercellular bone marrow due to a granulocytic proliferation, aCML distinguished by dysplasia in granulocytes ± other lineages. Absence of monocytosis, rare/no basophilia, or eosinophilia, <20% blasts, and exclusion of other MPN, MDS/MPN, and tyrosine kinase fusions, are mandated. Cytogenetic abnormalities are identified in ~1/3 of CNL and ~15-40% of aCML patients. The molecular signature of CNL is a driver mutation in colony-stimulating factor 3 receptor-classically T618I, documented in >80% of cases. Atypical CML harbors a complex genomic backdrop with high rates of recurrent somatic mutations in ASXL1, SETBP1, TET2, SRSF2, EZH2, and less frequently in ETNK1. Leukemic transformation rates are ~10-25% and 30-40% for CNL and aCML, respectively. Overall survival is poor: 15-31 months in CNL and 12-20 months in aCML. The Mayo Clinic CNL risk model for survival stratifies patients according to platelets <160 × 109/L (2 points), leukocytes >60 × 109/L (1 point), and ASXL1 mutation (1 point); distinguishing low- (0-1 points) versus high-risk (2-4 points) categories. The Mayo Clinic aCML risk model attributes 1 point each for: age >67 years, hemoglobin <10 g/dL, and TET2 mutation, delineating low- (0-1 risk factor) and high-risk (≥2 risk factors) subgroups. Management is risk-driven and symptom-directed, with no current standard of care. Most commonly used agents include hydroxyurea, interferon, Janus kinase inhibitors, and hypomethylating agents, though none are disease-modifying. Hematopoietic stem cell transplant is the only potentially curative modality and should be considered in eligible patients. Recent genetic profiling has disclosed CBL, CEBPA, EZH2, NRAS, TET2, and U2AF1 to represent high-risk mutations in both entities. Actionable mutations (NRAS/KRAS, ETNK1) have also been identified, supporting novel agents targeting involved pathways. Preclinical and clinical studies evaluating new drugs (e.g., fedratinib, phase 2) and combinations are detailed.

Disruption of KLHL6 Fuels Oncogenic Antigen Receptor Signaling in B-cell Lymphoma.

Pathomechanisms that activate oncogenic B-cell receptor (BCR) signaling in diffuse large B-cell lymphoma (DLBCL), are largely unknown. Kelch-like family member 6 (KLHL6) encoding a substrate-adapter for Cullin-3-RING E3 ubiquitin-ligase (CRL) with poorly established targets is recurrently mutated in DLBCL. By applying high-throughput protein interactome screens and functional characterization, we discovered that KLHL6 regulates BCR by targeting its signaling subunits CD79A and CD79B. Loss of physiological KLHL6 expression pattern was frequent among the MCD/C5-like activated B-cell DLBCLs and was associated with higher CD79B levels and dismal outcome. Mutations in the BTB domain of KLHL6 disrupted its localization and heterodimerization, and increased surface BCR levels and signaling, whereas Kelch domain mutants had the opposite effect. Malfunctions of KLHL6 mutants extended beyond proximal BCR signaling with distinct phenotypes from KLHL6 silencing. Collectively, our findings uncover how recurrent mutations in KLHL6 alter BCR signaling and induce actionable phenotypic characteristics in DLBCL.

Integrated mutational landscape analysis of poorly differentiated high-grade neuroendocrine carcinoma of the uterine cervix

High-grade neuroendocrine cervical cancers (NETc) are exceedingly rare, highly aggressive tumors. We analyzed 64 NETc tumor samples by whole-exome sequencing (WES). Human papillomavirus DNA was detected in 65.6% (42/64) of the tumors. Recurrent mutations were identified in PIK3CA, KMT2D/MLL2, K-RAS, ARID1A, NOTCH2, and RPL10. The top mutated genes included RB1, ARID1A, PTEN, KMT2D/MLL2, and WDFY3, a gene not yet implicated in NETc. Somatic CNV analysis identified two copy number gains (3q27.1 and 19q13.12) and five copy number losses (1p36.21/5q31.3/6p22.2/9q21.11/11p15.5). Also, gene fusions affecting the ACLY-CRHR1 and PVT1-MYC genes were identified in one of the eight samples subjected to RNA sequencing. To resolve evolutionary history, multiregion WES in NETc admixed with adenocarcinoma cells was performed (i.e., mixed-NETc). Phylogenetic analysis of mixed-NETc demonstrated that adenocarcinoma and neuroendocrine elements derive from a common precursor with mutations typical of adenocarcinomas. Over one-third (22/64) of NETc demonstrated a mutator phenotype of C > T at CpG consistent with deficiencies in MBD4, a member of the base excision repair (BER) pathway. Mutations in the PI3K/AMPK pathways were identified in 49/64 samples. We used two patient-derived-xenografts (PDX) (i.e., NET19 and NET21) to evaluate the activity of pan-HER (afatinib), PIK3CA (copanlisib), and ATR (elimusertib) inhibitors, alone and in combination. PDXs harboring alterations in the ERBB2/PI3K/AKT/mTOR/ATR pathway were sensitive to afatinib, copanlisib, and elimusertib (P < 0.001 vs. controls). However, combinations of copanlisib/afatinib and copanlisib/elimusertib were significantly more effective in controlling NETc tumor growth. These findings define the genetic landscape of NETc and suggest that a large subset of these highly lethal malignancies might benefit from existing targeted therapies.

Abstract LT10: Recurrent FBXW7 Mutations Bypass Wnt/β-catenin Addiction in Cancer

Abstract Inactivating mutations in RNF43 or gene fusions involving RSPO2/3 are potent activators of ligand-dependent Wnt signaling and drive multiple human cancers. Pharmacologically targeting the biogenesis of Wnt ligands, e.g., with PORCN inhibitors, is being investigated in clinical trials for treating RNF43-mutant/RSPO-fusion cancers. But, the therapeutic response is heterogeneous. Here we show that the tumor suppressor FBXW7 is frequently mutated in RNF43-mutant/RSPO-fusion tumors. Multiple RNF43-mutant/RSPO-fusion cancers harboring FBXW7 mutations show resistance to Wnt pathway blockade, while silencing FBXW7 by truncation or expressing a hotspot mutant in FBXW7-wildtype tumors leads to intrinsic drug resistance. Mechanistically, inactivation of FBXW7, the substrate recognition component of a SCF E3 ubiquitin ligase complex, stabilizes multiple oncoproteins especially Cyclin E and MYC, and antagonizes the cytostatic effect of Wnt inhibitors in these cancers. Moreover, although FBXW7 mutations do not mitigate β-catenin degradation upon Wnt inhibition, FBXW7 mutants instead lose dependence on β-catenin signaling, accompanied by dedifferentiation and loss of lineage specificity. These FBXW7-mutant Wnt/β-catenin-independent tumors are susceptible to multi-CDK inhibition by dinaciclib that targets both cell cycle and transcription. In summary, this study identifies FBXW7 mutations as a mechanism of Wnt independence and drug resistance in RNF43-mutant/RSPO-fusion cancers and reveals the potential of treating these cancers with multi-CDK inhibitors. Citation Format: Zheng Zhong, David Virshup. Recurrent FBXW7 Mutations Bypass Wnt/β-catenin Addiction in Cancer [abstract]. In: Proceedings of Frontiers in Cancer Science; 2023 Nov 6-8; Singapore. Philadelphia (PA): AACR; Cancer Res 2024;84(8_Suppl):Abstract nr LT10.

Validation of the 2022 European LeukemiaNet risk stratification for acute myeloid leukemia

This study aimed to validate the 2022 European LeukemiaNet (ELN) risk stratification for acute myeloid leukemia (AML). A total of 624 newly diagnosed AML patients from 1998 to 2014 were included in the analysis. Genetic profiling was conducted using targeted deep sequencing of 45 genes based on recurrent driver mutations. In total, 134 (21.5%) patients had their risk classification reassessed according to the 2022 ELN risk stratification. Among those initially classified as having a favorable risk in 2017 (n = 218), 31 and 3 patients were reclassified as having intermediate risk or adverse risk, respectively. Among the three subgroups, the 2022 ELN favorable-risk group showed significantly longer survival outcomes than the other groups. Within the 2017 ELN intermediate-risk group (n = 298), 21 and 46 patients were reclassified as having favorable risk or adverse risk, respectively, and each group showed significant stratifications in survival outcomes. Some patients initially classified as having adverse risk in 2017 were reclassified into the intermediate-risk group (33 of 108 patients), but no prognostic improvements were observed in this group. A multivariable analysis identified the 2022 ELN risk stratification, age, and receiving allogeneic hematopoietic cell transplantation as significant prognostic factors for survival. The 2022 ELN risk stratification enables more precise decisions for proceeding with allogeneic hematopoietic cell transplantation for AML patients.

Combined deletion of MEN1, ATRX and PTEN triggers development of high-grade pancreatic neuroendocrine tumors in mice

Pancreatic neuroendocrine tumors (PanNETs) are a heterogeneous group of tumors that exhibit an unpredictable and broad spectrum of clinical presentations and biological aggressiveness. Surgical resection is still the only curative therapeutic option for localized PanNET, but the majority of patients are diagnosed at an advanced and metastatic stage with limited therapeutic options. Key factors limiting the development of new therapeutics are the extensive heterogeneity of PanNETs and the lack of appropriate clinically relevant models. In that context, genomic sequencing of human PanNETs revealed recurrent mutations and structural alterations in several tumor suppressors. Here, we demonstrated that combined loss of MEN1, ATRX, and PTEN, tumor suppressors commonly mutated in human PanNETs, triggers the development of high-grade pancreatic neuroendocrine tumors in mice. Histopathological evaluation and gene expression analyses of the developed tumors confirm the presence of PanNET hallmarks and significant overlap in gene expression patterns found in human disease. Thus, we postulate that the presented novel genetically defined mouse model is the first clinically relevant immunocompetent high-grade PanNET mouse model.

Substantial viral diversity in bats and rodents from East Africa: insights into evolution, recombination, and cocirculation.

Zoonotic viruses cause substantial public health and socioeconomic problems worldwide. Understanding how viruses evolve and spread within and among wildlife species is a critical step when aiming for proactive identification of viral threats to prevent future pandemics. Despite the many proposed factors influencing viral diversity, the genomic diversity and structure of viral communities in East Africa are largely unknown. Using 38.3Tb of metatranscriptomic data obtained via ultradeep sequencing, we screened vertebrate-associated viromes from 844 bats and 250 rodents from Kenya and Uganda collected from the wild. The 251 vertebrate-associated viral genomes of bats (212) and rodents (39) revealed the vast diversity, host-related variability, and high geographic specificity of viruses in East Africa. Among the surveyed viral families, Coronaviridae and Circoviridae showed low host specificity, high conservation of replication-associated proteins, high divergence among viral entry proteins, and frequent recombination. Despite major dispersal limitations, recurrent mutations, cocirculation, and occasional gene flow contribute to the high local diversity of viral genomes. The present study not only shows the landscape of bat and rodent viromes in this zoonotic hotspot but also reveals genomic signatures driven by the evolution and dispersal of the viral community, laying solid groundwork for future proactive surveillance of emerging zoonotic pathogens in wildlife. Video Abstract.