Chromosomal Copy Research Articles

EPEN-28. NOVEL TARGET IDENTIFICATION IN RECURRENT POSTERIOR FOSSA EPENDYMOMA GROUP A

Abstract BACKGROUND Posterior fossa ependymoma group A (PF-EPN-A) are an aggressive subgroup of ependymal tumors which occur predominantly in infants and possess a poor prognosis. Treatment is limited to surgical resection and adjuvant radiation with no approved chemotherapies or targeted therapies available. Despite treatment efforts, nearly half of all PF-EPN-A cases will experience tumor recurrence within a decade of initial diagnosis. Our current understanding of relapse is limited to clinical risk stratification based on subtotal resection of the primary tumor, male sex and specific chromosomal copy number aberrations. In an effort to overcome the shortcomings of current literature on PF-EPN-A recurrence, we present a concerted effort to investigate the biology of both recurrent human tissue specimens and patient-derived cell models to identify novel drivers of recurrence. METHODS Utilizing a multi-omics approach, we have conducted transcriptomic (bulk RNA-Seq), proteomic and phosphoproteomic (LC-MS/MS) analyses in order to identify molecular pathways that are enriched in recurrent disease as compared to primaries. We have also performed genome-wide CRISPR essentiality screens to further pinpoint essential genes and pathways with therapeutic potential. RESULTS Through the comparison of primary and recurrent PF-EPN-A samples, we have identified both previously implicated and novel genes and pathways in recurrent disease. Our multi-omic analyses identified the upregulation of genes involved in DNA repair, DNA damage response and cell cycle pathways in recurrent PF-EPN-A. CONCLUSIONS Our combined approach has enabled the identification of novel targets with therapeutic potential in the treatment of recurrent PF-EPN-A. The identified targets will be validated using a combination of drug screening and knockdown approaches in vitro. Top candidates will be further validated in vivo with established recurrent xenograft mouse models. PF-EPN-A is an aggressive disease with limited treatment options and the identification of novel targets with potential therapeutic utility will allow us to better treat this patient population.

MDB-105. CONSTRUCTION OF AN INTERACTIVE MEDULLOBLASTOMA VISUALIZATION PORTAL FROM MOLECULAR AND CLINICAL DATA DERIVED FROM THREE MULTI-INSTITUTIONAL PROTOCOLS (ACNS0331, SJMB03, ACNS0332) TO COMPARE, CONTRAST, AND INVESTIGATE COHORTS AS A MEANS TO REFINE THERAPY

Abstract BACKGROUND Medulloblastoma (MB) patients display a heterogeneous mix of molecular and clinical characteristics that influence tumor behavior and survival. We hypothesized that if these multiple characteristics could be incorporated into an organized, searchable, and interactive dataset, this would advance our understanding and improve treatment of this disease. Consequently, we organized multifaceted datasets into an interactive portal equipped with cutting-edge visualization tools. METHODS Clinical and molecular data from the ACNS0331, SJMB03, and ACNS0332 protocols were collated and harmonized. A data dictionary was built to capture demographics, treatment, histology, methylation classification, mutations, chromosomal copy number variations and outcomes. To display the data, a software framework was applied. Five visualization methods were implemented (summary plots, sample view, scatter plots, sample matrix, and survival plots) in an interconnected manner such that these “cross-talk” with each other. RESULTS Data from 898 patients with MB were incorporated: 131 WNT, 151 SHH, 220 G3, 396 G4. The portal features enabled the creation of custom cohorts that could be instantly queried by any of the dictionary terms. For example, cohorts could be customized to include only cases with a mutation of the user’s choice and analyzed by molecular group, gender, age at diagnosis, or treatment given. Survival of patients with SHH-MB harboring TP53 mutations could be compared to patients with WNT-MB harboring TP53 mutations. Moreover, the influence of MB subtype (e.g. G34_I-VIII), focal amplifications (MYC, MYCN) and whole chromosome aberration phenotype on survival could be queried across treatment regimens accounting for metastatic status and/or additional variables of the user’s choice. CONCLUSION The integration of molecular and clinical data from multiple trials into an interactive visualization data portal presents an unprecedented resource for research and clinical practice. This portal facilitates answering highly specific questions about mutational frequency and patient outcome by molecular and clinical risk factors.

Additional copies of 1q negatively impact the outcome of multiple myeloma patients and induce transcriptomic deregulation in malignant plasma cells

Additional copies of chromosome 1 long arm (1q) are frequently found in multiple myeloma (MM) and predict high-risk disease. Available data suggest a different outcome and biology of patients with amplification (Amp1q, ≥4 copies of 1q) vs. gain (Gain1q, 3 copies of 1q) of 1q. We evaluated the impact of Amp1q/Gain1q on the outcome of newly diagnosed MM patients enrolled in the FORTE trial (NCT02203643). Among 400 patients with available 1q data, 52 (13%) had Amp1q and 129 (32%) Gain1q. After a median follow-up of 62 months, median progression-free survival (PFS) was 21.2 months in the Amp1q group, 54.9 months in Gain1q, and not reached (NR) in Normal 1q. PFS was significantly hampered by the presence of Amp1q (HR 3.34 vs. Normal 1q, P < 0.0001; HR 1.99 vs. Gain1q, P = 0.0008). Patients with Gain1q had also a significantly shorter PFS compared with Normal 1q (HR 1.68, P = 0.0031). Concomitant poor prognostic factors or the failure to achieve MRD negativity predicted a median PFS < 12 months in Amp1q patients. Carfilzomib–lenalidomide–dexamethasone plus autologous stem cell transplantation treatment improved the adverse effect of Gain1q but not Amp1q. Transcriptomic data showed that additional 1q copies were associated with deregulation in apoptosis signaling, p38 MAPK signaling, and Myc-related genes.

Whole-exome-based single nucleotide variants and copy number analysis for prenatal diagnosis of compound heterozygosity of SMPD4.

Biallelic loss-of-function variants in SMPD4 cause a rare and severe neurodevelopmental disorder. These variants have been identified in a group of children with neurodevelopmental disorders with microcephaly, arthrogryposis, and structural brain anomalies. SMPD4 encodes a sphingomyelinase that hydrolyzes sphingomyelin into ceramide at neutral pH and can thereby affect membrane lipid homeostasis. SMPD4 localizes to the membranes of the endoplasmic reticulum and nuclear envelope and interacts with nuclear pore complexes. For the efficient prenatal diagnosis of rare and undiagnosed diseases, the parallel detection of copy number variants (CNVs) and single nucleotide variants using whole-exome analysis is required. A physical examination of the parents was performed. Karyotype and whole-exome analysis were performed for the fetus and the parents. A fetus with microcephaly and arthrogryposis; biallelic null variants (c.387-1G>A; Chr2[GRCh38]: g.130142742_130202459del) were detected by whole-exome sequencing (WES). We have reported for the first time the biallelic loss-of-function mutations in SMPD4 in patients born to unrelated parents in China. WES could replace chromosomal microarray analysis and copy number variation sequencing as a more cost-effective genetic test for detecting CNVs and diagnosing highly heterogeneous conditions.

Genome-Scale Multimodal Analysis of Cell-Free DNA Whole-Methylome Sequencing for Noninvasive Esophageal Cancer Detection.

Simultaneous profiling of cell-free DNA (cfDNA) methylation and fragmentation features to improve the performance of cfDNA-based cancer detection is technically challenging. We developed a method to comprehensively analyze multimodal cfDNA genomic features for more sensitive esophageal squamous cell carcinoma (ESCC) detection. Enzymatic conversion-mediated whole-methylome sequencing was applied to plasma cfDNA samples extracted from 168 patients with ESCC and 251 noncancer controls. ESCC characteristic cfDNA methylation, fragmentation, and copy number signatures were analyzed both across the genome and at accessible cis-regulatory DNA elements. To distinguish ESCC from noncancer samples, a first-layer classifier was developed for each feature type, the prediction results of which were incorporated to construct the second-layer ensemble model. ESCC plasma genome displayed global hypomethylation, altered fragmentation size, and chromosomal copy number alteration. Methylation and fragmentation changes at cancer tissue-specific accessible cis-regulatory DNA elements were also observed in ESCC plasma. By integrating multimodal genomic features for ESCC detection, the ensemble model showed improved performance over individual modalities. In the training cohort with a specificity of 99.2%, the detection sensitivity was 81.0% for all stages and 70.0% for stage 0-II. Consistent performance was observed in the test cohort with a specificity of 98.4%, an all-stage sensitivity of 79.8%, and a stage 0-II sensitivity of 69.0%. The performance of the classifier was associated with the disease stage, irrespective of clinical covariates. This study comprehensively profiles the epigenomic landscape of ESCC plasma and provides a novel noninvasive and sensitive ESCC detection approach with genome-scale multimodal analysis.

Non-invasive pre-implantation genetic testing's reliability for aneuploidy using Cell-free DNA in embryo culture media

ObjectiveThe presence of embryonic cell-free DNA (cfDNA) in spent embryo culture media (SECM) may offer valuable advantages for non-invasive testing of embryo ploidy or genetic characteristics compared to trophectoderm (TE) biopsy. This study aimed to assess the diagnostic potential of SECM cfDNA as a non-invasive sample for chromosomal copy number testing in blastocysts within the clinical setting of in-vitro fertilization. MethodThis prospective observational study collected 28 SECM cfDNA samples matched with TE biopsy samples from 21 infertile couples who underwent IVF-PGT-A cycles. SECM samples were obtained from blastocysts that were cultured for approximately 5/6 days in an uninterrupted time-lapse incubator. Both sets of samples were collected during the biopsy procedure. The Variseq Illumina platform was utilized for ploidy measurement. The study evaluated the informativity and interpretability of SECM cfDNA, concordance of general ploidy status, and sex chromosome agreement between the two sample types. ResultsSECM cfDNA had a high informativity rate (100 %) after double amplification procedure, with a result interpretability of 93 %. Two out of the 28 SECM cfDNA samples were uninterpretable and regarded as overall noise samples. The diagnostic potential of SECM cfDNA, when compared to TE biopsy the standard reference, was relatively low at 50 %. Maternal DNA contamination remains the major obstacle that hinders the widespread clinical adoption of SECM cfDNA in the routine practice of pre-implantation genetic testing for aneuploidy within IVF settings. ConclusionA significant modification must be implemented in the IVF laboratory to minimize DNA contamination and this necessitates suggesting adjustments to oocyte denudation, embryo culture media preparation, and sample collection procedures.

Chromosomal instability induced in cancer can enhance macrophage-initiated immune responses that include anti-tumor IgG.

Solid tumors generally exhibit chromosome copy number variation, which is typically caused by chromosomal instability (CIN) in mitosis. The resulting aneuploidy can drive evolution and associates with poor prognosis in various cancer types as well as poor response to T-cell checkpoint blockade in melanoma. Macrophages and the SIRPα-CD47 checkpoint are understudied in such contexts. Here, CIN is induced in poorly immunogenic B16F10 mouse melanoma cells using spindle assembly checkpoint MPS1 inhibitors that generate persistent micronuclei and diverse aneuploidy while skewing macrophages toward a tumoricidal 'M1-like' phenotype based on markers and short-term anti-tumor studies. Mice bearing CIN-afflicted tumors with wild-type CD47 levels succumb similar to controls, but long-term survival is maximized by SIRPα blockade on adoptively transferred myeloid cells plus anti-tumor monoclonal IgG. Such cells are the initiating effector cells, and survivors make de novo anti-cancer IgG that not only promote phagocytosis of CD47-null cells but also suppress tumor growth. CIN does not affect the IgG response, but pairing CIN with maximal macrophage anti-cancer activity increases durable cures that possess a vaccination-like response against recurrence.

Chromosomal instability induced in cancer can enhance macrophage-initiated immune responses that include anti-tumor IgG

Solid tumors generally exhibit chromosome copy number variation, which is typically caused by chromosomal instability (CIN) in mitosis. The resulting aneuploidy can drive evolution and associates with poor prognosis in various cancer types as well as poor response to T-cell checkpoint blockade in melanoma. Macrophages and the SIRPα-CD47 checkpoint are understudied in such contexts. Here, CIN is induced in poorly immunogenic B16F10 mouse melanoma cells using spindle assembly checkpoint MPS1 inhibitors that generate persistent micronuclei and diverse aneuploidy while skewing macrophages toward a tumoricidal ‘M1-like’ phenotype based on markers and short-term anti-tumor studies. Mice bearing CIN-afflicted tumors with wild-type CD47 levels succumb similar to controls, but long-term survival is maximized by SIRPα blockade on adoptively transferred myeloid cells plus anti-tumor monoclonal IgG. Such cells are the initiating effector cells, and survivors make de novo anti-cancer IgG that not only promote phagocytosis of CD47-null cells but also suppress tumor growth. CIN does not affect the IgG response, but pairing CIN with maximal macrophage anti-cancer activity increases durable cures that possess a vaccination-like response against recurrence.

Natural proteome diversity links aneuploidy tolerance to protein turnover

Accessing the natural genetic diversity of species unveils hidden genetic traits, clarifies gene functions and allows the generalizability of laboratory findings to be assessed. One notable discovery made in natural isolates of Saccharomyces cerevisiae is that aneuploidy—an imbalance in chromosome copy numbers—is frequent1,2 (around 20%), which seems to contradict the substantial fitness costs and transient nature of aneuploidy when it is engineered in the laboratory3–5. Here we generate a proteomic resource and merge it with genomic1 and transcriptomic6 data for 796 euploid and aneuploid natural isolates. We find that natural and lab-generated aneuploids differ specifically at the proteome. In lab-generated aneuploids, some proteins—especially subunits of protein complexes—show reduced expression, but the overall protein levels correspond to the aneuploid gene dosage. By contrast, in natural isolates, more than 70% of proteins encoded on aneuploid chromosomes are dosage compensated, and average protein levels are shifted towards the euploid state chromosome-wide. At the molecular level, we detect an induction of structural components of the proteasome, increased levels of ubiquitination, and reveal an interdependency of protein turnover rates and attenuation. Our study thus highlights the role of protein turnover in mediating aneuploidy tolerance, and shows the utility of exploiting the natural diversity of species to attain generalizable molecular insights into complex biological processes.

Increased hippocampal epigenetic age in the Ts65Dn mouse model of Down Syndrome.

Down syndrome (DS) is a segmental progeroid genetic disorder associated with multi-systemic precocious aging phenotypes, which are particularly evident in the immune and nervous systems. Accordingly, people with DS show an increased biological age as measured by epigenetic clocks. The Ts65Dn trisomic mouse, which harbors extra-numerary copies of chromosome 21 (Hsa21)-syntenic regions, was shown to recapitulate several progeroid features of DS, but no biomarkers of age have been applied to it so far. In this pilot study, we used a mouse-specific epigenetic clock to measure the epigenetic age of hippocampi from Ts65Dn and euploid mice at 20 weeks. Ts65Dn mice showed an increased epigenetic age in comparison with controls, and the observed changes in DNA methylation partially recapitulated those observed in hippocampi from people with DS. Collectively, our results support the use of the Ts65Dn model to decipher the molecular mechanisms underlying the progeroid DS phenotypes.

Prenatal diagnosis and pregnancy outcomes in fetuses with ventriculomegaly.

Genetic etiology plays a critical role in fetal ventriculomegaly (VM). However, the studies on chromosomal copy number variants (CNVs) in fetal VM are limited. This study aimed to investigate the chromosomal CNVs in fetuses with mild to moderate VM, and explore its genotype-phenotype correlation. A total of 242 fetuses with mild to moderate VM detected by prenatal ultrasound were enrolled in our study from October 2018 to October 2022. All cases underwent chromosomal microarray analysis (CMA) and G-banding simultaneously. All VM cases were classified different subgroups according to the maternal age, severity, VM distribution and presence/absence of other ultrasound abnormalities. The pregnancy outcomes and health conditions after birth were followed up. We also performed a pooled analysis regarding likely pathogenic and pathogenic CNVs (LP/P CNVs) for VM. The detection rate of chromosomal abnormalities by karyotyping was 9.1% (22/242), whereas it was 16.5% (40/242) when CMA was conducted (P < 0.05). The total detection rate of chromosomal abnormalities by karyotyping and CMA was 21.1% (51/242). A 12.0% incremental yield of CMA over karyotyping was observed. The detection rate of total genetic variants in fetuses with bilateral VM was significantly higher than in fetuses with unilateral VM (30.0% vs. 16.7%, P = 0.017). No significant differences were discovered between isolated VM and non-isolated VM, or between mild and moderate VM, or between advanced maternal age (AMA) and non-AMA (all P > 0.05). 28 fetuses with VM were terminated and 214 fetuses were delivered: one presented developmental delay and one presented congenital heart disease. The VM cases with both positive CMA and karyotypic results had a higher rate of termination of pregnancy than those with either a positive CMA or karyotypic result, or both negative testing results (P < 0.001). The combination of CMA and karyotyping should be adopted to improve the positive detection rate of chromosomal abnormalities for VM. The total genetic abnormalities detected using both techniques would affect the final pregnancy outcomes. LP/P CNVs at 16p11.2, 17p13, and 22q11.21 were identified as the top three chromosomal hotspots associated with VM, which would enable genetic counselors to provide more precise genetic counseling for VM pregnancies.

A clinical case of trisomy on chromosome 18 (Edwards Syndrome)

Edwards syndrome (trisomy on chromosome 18) is a genetic disorder caused by the presence of an extra copy of the eighteenth chromosome in humans. It is the second most common chromosomal disorder after Down syndrome. The frequency of Edwards syndrome among newborns is 1:5000–1:7000. The ratio of boys to girls is 1:3. The karyotype of sick girls and boys is 47, XX+18, 47, XY+18, and 47, XY+18, respectively. Patients are born with low birth weight (about 2 kg), they have delayed growth and development, mental retardation, wide fontanels at birth and open cranial sutures, the thorax is wider and shorter than normal, the mandible and mouth opening are small. The eye slits are narrow and short, the auditory orifices are deformed and sometimes absent. There are defects of the heart and large vessels, hypoplasia of the cerebellum and corpus callosum. 5–10% survive to the age of one year, all survivors are profound oligophrenics [1–4].

Phenotypic, Genomic, and Transcriptomic Heterogeneity in a Pancreatic Cancer Cell Line.

To evaluate the suitability of the MIA PaCa-2 cell line for studying pancreatic cancer intratumor heterogeneity, we aim to further characterize the nature of MIA PaCa-2 cells' phenotypic, genomic, and transcriptomic heterogeneity. MIA PaCa-2 single-cell clones were established through flow cytometry. For the phenotypic study, we quantified the cellular morphology, proliferation rate, migration potential, and drug sensitivity of the clones. The chromosome copy number and transcriptomic profiles were quantified using SNPa and RNA-seq, respectively. Four MIA PaCa-2 clones showed distinctive phenotypes, with differences in cellular morphology, proliferation rate, migration potential, and drug sensitivity. We also observed a degree of genomic variations between these clones in form of chromosome copy number alterations and single nucleotide variations, suggesting the genomic heterogeneity of the population, and the intrinsic genomic instability of MIA PaCa-2 cells. Lastly, transcriptomic analysis of the clones also revealed gene expression profile differences between the clones, including the uniquely regulated ITGAV , which dictates the morphology of MIA PaCa-2 clones. MIA PaCa-2 is comprised of cells with distinctive phenotypes, heterogeneous genomes, and differential transcriptomic profiles, suggesting its suitability as a model to study the underlying mechanisms behind pancreatic cancer heterogeneity.

Trisomy 18: Prenatal Diagnosis and Outcome in a Tertiary Care Fetal Medicine Center in South India

AbstractEdwards' syndrome (trisomy 18) is the second most common aneuploidy known in humans, with an overall incidence of 1 in 6,000 live births. It occurs due to the presence of complete or part of an extra copy of chromosome 18 in all or a few body cells of the affected fetus, and it causes major anomalies in the organ systems. Despite this, an accurate diagnosis is often not made antenatally due to its very varied phenotype and the subtle nature of some of the common and consistent findings associated with this condition. This leads to lapses or delays in cytogenetic confirmation as well as delays in decision regarding termination of pregnancies with this mostly lethal fetal aneuploidy. We describe the prenatal profile of 45 confirmed cases of trisomy 18 at a tertiary fetal medicine unit. The presence of a combination of ultrasound (US) findings described in these cases will help alert sonologists and clinicians to suspect this condition and offer a confirmative cytogenetic test without delay for prenatal diagnosis. This study describes the prenatal diagnostic profile of cytogenetically confirmed trisomy 18 cases in a tertiary fetal medicine center in India. A retrospective analysis of records of 45 prenatally diagnosed trisomy 18 cases at a single tertiary fetal medicine center over a period of 11 years was done. Data were collected to describe maternal demography, indication for evaluation, major and minor US findings (trimester-wise), type of invasive test, and gestational age at diagnosis. Outcomes in terms of pregnancy termination, miscarriage, stillbirth, or livebirth were documented. Presenting at a mean maternal age and gestation age of 31.7 years and 22 + 5 weeks, respectively, 41/45 (91%) fetuses showed major and 40/45 (89%) showed minor US findings with an overall US sensitivity of 100%. The most common major US finding was a cardiac anomaly in 26 (57.8%) patients, while clenched fist with pointing index finger, observed in 17 (37.8%) cases, was the most common minor US finding. Fetal growth restriction (FGR) was noted in 20 (44.4%) patients. After cytogenetic confirmation, 37.8% underwent termination, 17.8% had a fetal demise, and only 11.1% had live birth with the longest survival noted at 5.5 months postnatally. Gender was documented in 13 fetuses with a male-to-female ratio of 0.6. A meticulously performed US examination can detect a combination of anomalies that could alert the sonologist to the possibility of trisomy 18. While the US profile could vary among fetuses, an understanding of the spectrum of the anomalies commonly seen in these fetuses would enable caregivers to reach an early accurate diagnosis, and offer appropriate genetic counseling and pregnancy decisions in these cases.

Chromosome Transplantation: Opportunities and Limitations.

There are thousands of rare genetic diseases that could be treated with classical gene therapy strategies such as the addition of the defective gene via viral or non-viral delivery or by direct gene editing. However, several genetic defects are too complex for these approaches. These "genomic mutations" include aneuploidies, intra and inter chromosomal rearrangements, large deletions, or inversion and copy number variations. Chromosome transplantation (CT) refers to the precise substitution of an endogenous chromosome with an exogenous one. By the addition of an exogenous chromosome and the concomitant elimination of the endogenous one, every genetic defect, irrespective of its nature, could be resolved. In the current review, we analyze the state of the art of this technique and discuss its possible application to human pathology. CT might not be limited to the treatment of human diseases. By working on sex chromosomes, we showed that female cells can be obtained from male cells, since chromosome-transplanted cells can lose either sex chromosome, giving rise to 46,XY or 46,XX diploid cells, a modification that could be exploited to obtain female gametes from male cells. Moreover, CT could be used in veterinary biology, since entire chromosomes containing an advantageous locus could be transferred to animals of zootechnical interest without altering their specific genetic background and the need for long and complex interbreeding. CT could also be useful to rescue extinct species if only male cells were available. Finally, the generation of "synthetic" cells could be achieved by repeated CT into a recipient cell. CT is an additional tool for genetic modification of mammalian cells.

Prenatal diagnosis of fetal microdeletion and microduplication syndromes among pregnant women with advanced maternal ages

To assess the value of combined chromosomal karyotyping and chromosomal microarray analysis (CMA) and/or copy number variation sequencing (CNV-seq) for the prenatal diagnosis for women with advanced maternal ages, and to explore the challenges of prenatal genetic counseling brought by the types of fetal CNVs and uncertainty of related phenotypes. A retrospective analysis was carried out on 1 841 women with advanced maternal age who underwent interventional prenatal diagnosis at the Prenatal Diagnosis Center of Xiamen University Affiliated Women and Children's Hospital from January 2017 to December 2020. Routine chromosomal karyotyping analysis and CMA/CNV-seq detection were carried out. CMA/CNV-seq had detected pathogenic variants in 2 cases which had failed karyotyping analysis. Two hundred and twenty one fetal chromosomal abnormalities were detected by karyotyping analysis, among which 187 were detected by CMA/CNV-seq. CMA/CNV-seq analysis of 23 cases with balanced chromosome structural aberrations and 10 cases with low proportion mosaicisms (including a marker chromosome) had yielded a negative result. In addition, 26 cases (26/1 841, 1.4%) with pathogenic CNVs were discovered among those with a normal karyotype, of which 13 (50.0%) were recurrent CNVs associated with neurocognitive impairment, with 22q11.21 microdeletions and microduplications being the most common types (26.92%). The combination of karyotyping analysis and CMA/CNV-seq not only increased the rate of prenatal diagnosis, but also complemented with each other, which has facilitated genetic counseling and formulation of prenatal diagnosis strategy for the affected families.

Detection of chromosomal instability using ultrasensitive chromosomal aneuploidy detection in the diagnosis of precancerous lesions of gastric cancer.

The diagnosis of Precancerous Lesions of Gastric Cancer (PLGC) is challenging in clinical practice. We conducted a clinical study by analyzing the information of relevant chromosome copy number variations (CNV) in the TCGA database followed by the UCAD technique to evaluate the value of Chromosomal Instability (CIN) assay in the diagnosis of PLGC. Based on the screening of gastric cancer related data in TCGA database, CNV analysis was performed to explore the information of chromosome CNV related to gastric cancer. Based on the gastroscopic pathology results, 12 specimens of patients with severe atrophy were screened to analyze the paraffin specimens of gastric mucosa by UCAD technology, and to explore the influence of related factors on them. The results of CNV in TCGA database suggested that chromosome 7, 8, and 17 amplification was obvious in patients with gastric cancer. UCAD results confirmed that in 12 patients with pathologic diagnosis of severe atrophy, five of them had positive results of CIN, with a positive detection rate of 41.7%, which was mainly manifested in chromosome seven and chromosome eight segments amplification. We also found that intestinalization and HP infection were less associated with CIN. And the sensitivity of CIN measurement results was significantly better than that of tumor indicators. The findings suggest that the diagnosis of PLGC can be aided by UCAD detection of CIN, of which Chr7 and 8 may be closely related to PLGC.

Abstract LB228: Evolutionary trajectories of lung cancer in never smokers

Abstract Purpose of the study Elucidating evolutionary trajectories of cancers allows us to understand the key events, and the order in which they occur, throughout their development. This can help us to find important associations with tumor progression and prognosis. Our aim was to perform de novo identification of the evolutionary trajectories within Sherlock-lung, with a dataset containing the largest collection of lung cancer in never smokers (LCINS) samples ever analyzed. Experimental procedures Our Plackett-Luce ordering model utilized copy number data from Battenberg and mutation cancer cell fraction (CCF) data from DPClust. Frequently-occurring copy number events and driver mutations are ordered within each sample using their copy number states and CCFs. An aggregate ordering is then calculated for a sample set. Mixture model analysis identifies subsets of samples displaying distinct orders of events, uncovering diverse evolutionary trajectories within a tumor set. Dataset The Sherlock-lung whole genome sequencing dataset (n=1217) was filtered to the samples that allowed us to identify subclonal expansions. Samples required at least 10 reads per chromosome copy and a minimum cellularity of 30%. This provided 458 LCINS samples of various histologies. 155 smoker samples were also analyzed for comparison. Results We identified two subsets of LCINS tumors following distinct evolutionary trajectories. The “loss-based” subset commonly saw whole genome duplication (WGD) combined with copy number losses occurring earlier, and at higher prevalence, than gains. Contrastingly, in the “gain-based” subset, WGD was relatively rare but ploidy increased via copy number gains, which were more prevalent than losses. Interestingly, these different trajectories converged on similar overall copy number states. The loss-based subset had a higher mutational burden and a higher proportion of the genome altered, and followed a more smoker-like trajectory than the gain-based subset. Considering these differences alongside the convergence in copy number states, it is intriguing that survival times were similar between the two subsets. Copy number events defined the difference between the two trajectories. However, driver mutations also played important roles in tumor evolution in LCINS. TP53 and EGFR mutations were associated with greater genomic instability. Conversely, KRAS mutations were associated with more stable genomes. Samples with early clonal mutations in TP53, ERBB2, and PIK3CA, as well as those with a copy number gain of ERBB2, exhibited shorter survival times. Conclusions Two distinct evolutionary trajectories of LCINS were identified by de novo Plackett-Luce event ordering analysis. The contrast between the subgroups was defined by different paths of copy number activity, but they ultimately converged on similar overall copy number states and outcomes. Key early driver mutations influenced genomic instability and survival times. Citation Format: Christopher Wirth, Tongwu Zhang, Wei Zhao, Phuc Hoang, Jian Sang, Nathaniel Rothman, Marcos Díaz-Gay, Ruxandra Teslo, Naser Ansari-Pour, Máire Ní Leathlobhair, Iliana Peneva, William Eagles, Lixing Yang, Ludmil Alexandrov, David C. Wedge, Maria Teresa Landi. Evolutionary trajectories of lung cancer in never smokers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB228.

Targeted phasing of 2–200 kilobase DNA fragments with a short-read sequencer and a single-tube linked-read library method

In the human genome, heterozygous sites refer to genomic positions with a different allele or nucleotide variant on the maternal and paternal chromosomes. Resolving these allelic differences by chromosomal copy, also known as phasing, is achievable on a short-read sequencer when using a library preparation method that captures long-range genomic information. TELL-Seq is a library preparation that captures long-range genomic information with the aid of molecular identifiers (barcodes). The same barcode is used to tag the reads derived from the same long DNA fragment within a range of up to 200 kilobases (kb), generating linked-reads. This strategy can be used to phase an entire genome. Here, we introduce a TELL-Seq protocol developed for targeted applications, enabling the phasing of enriched loci of varying sizes, purity levels, and heterozygosity. To validate this protocol, we phased 2–200 kb loci enriched with different methods: CRISPR/Cas9-mediated excision coupled with pulse-field electrophoresis for the longest fragments, CRISPR/Cas9-mediated protection from exonuclease digestion for mid-size fragments, and long PCR for the shortest fragments. All selected loci have known clinical relevance: BRCA1, BRCA2, MLH1, MSH2, MSH6, APC, PMS2, SCN5A-SCN10A, and PKI3CA. Collectively, the analyses show that TELL-Seq can accurately phase 2–200 kb targets using a short-read sequencer.

Abstract LB226: Deciphering lung adenocarcinoma evolution and the role of LINE-1 retrotransposition

Abstract Lung cancer is the leading cause of cancer-related mortality worldwide. Understanding lung cancer evolutionary dynamics can help identify tools to intercept its growth and suggest strategies for treatment. Multiple factors can impact the tumors’ natural history and distinctly affect growth rate. However, research on the evolutionary trajectories of lung cancer across demographic or exposure scenarios remains inadequate. Additionally, the roles of mutational processes and complex genomic alterations on the evolution of lung cancer are still largely unexplored. In the largest genomic study of lung cancer to date, we analyzed deep whole-genome sequencing (~ 81x) and other omics data of 1217 lung cancers from the Sherlock-Lung study. To ensure adequate statistical power for identifying subclone architectures and constructing lung cancer evolutionary histories, we utilized a metric known as NRPCC (number of reads per tumor chromosomal copy) to select 542 lung adenocarcinoma (LUAD) samples for clonal evolution analyses, including 186 and 181 samples from never-smoker subjects of European and Asian ancestry, respectively, and 121 samples from smokers of European ancestry. We found that major driver genes and exogenous mutations contribute to tumor initiation, while copy number gains and endogenous processes appear later in tumor evolution. Tumors harboring EGFR mutations in never-smoker females of European descent show long latency, while tumors with KRAS mutations have shorter latency regardless of ancestry and sex. Notably, tumors harboring the mutational signature ID2 have short latency and aggressive phenotype, accompanied by increased genomic instability, elevated hypoxia scores, high CpG methylator phenotype, low neoantigen burden, and propensity to develop metastasis. We show that LINE-1 retrotransposition-induced mutagenesis contributes to the origin of ID2 mutations. The transcriptional factor ZNF695, a member of the KZFP family, up-regulated in LUAD, appears to contribute to LINE-1 retrotransposition through a dominant-negative effect and LINE-1 promoter demethylation. In a multivariate analysis of genomics, exposures and demographic factors, LUAD latency was most significantly associated with ID2, followed by EGFR mutations, KRAS mutations, and sex, suggesting an independent impact of these factors on LUAD evolution. Our findings underscore the complex interplay of ancestry, sex, exogenous mutagenesis, epigenetic regulation, and LINE-1 retrotransposition in shaping LUAD evolutionary trajectories, paving the way for potential targeted therapeutic interventions. Citation Format: Tongwu Zhang, Wei Zhao, Christopher Wirth, Marcos Díaz-Gay, Jinhu Yin, Phuc H. Hoang, Jian Sang, John McElderry, Alyssa Klein, Azhar Khandekar, Caleb Hartman, Jennifer Rosenbaum, Frank Colon-Matos, Kristine M. Jones, Neil E. Caporaso, Robert Homer, Angela C. Pesatori, Dario Consonni, Lixing Yang, Bin Zhu, Jianxin Shi, Kevin Brown, Nathaniel Rothman, Stephen J. Chanock, Ludmil B. Alexandrov, Jiyeon Choi, Maurizio Cardelli, Qing Lan, Martin A. Nowak, David C. Wedge, Maria Teresa Landi. Deciphering lung adenocarcinoma evolution and the role of LINE-1 retrotransposition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB226.