Landscape Of Somatic Mutations Research Articles

Somatic mutational landscape reveals mutational signatures and significantly mutated genes of cancer immunotherapeutic outcome and sex disparities

BackgroundCurrently developed molecular markers can predict the effectiveness of cancer immunotherapy and screen beneficiaries to some extent, but they are not stable enough. Therefore, there is an urgent need for discovering novel biomarkers. At the same time, sex factor plays a vital role in the response to immunotherapy, so it is particularly important to identify sex-related molecular indicators.MethodsWe integrated a pan-cancer cohort consisting of 2348 cancer patients who received immune checkpoint inhibitors and targeted sequencing. Using somatic mutation profiles, we identified mutational signatures, molecular subtypes, and frequently mutated genes, and analyzed their relationships with immunotherapeutic outcomes. We also explored sex disparities of determined biomarkers in response to treatments.ResultsWe found that male patients exhibited better immunotherapy outcomes and higher tumor mutational burden. A total of seven mutational signatures were identified, among which signatures 1 and 3 were associated with worse immunotherapy outcomes, while signatures 2 and 6 correlated with better outcomes. Gender-based analysis revealed that mutational signature 1 continued to show a worse immunotherapy outcome in female patients, whereas signature 6 demonstrated a better outcome in male patients. Based on mutational activities, we identified four potential molecular subtypes with gender differences and relevance to treatment outcomes. PI3K-AKT, RAS signaling pathways, and 68 significantly mutated genes were identified to be associated with immunotherapy outcomes, with nine genes (i.e., ATM, ATRX, DOT1L, EP300, EPHB1, NOTCH1, PBRM1, RBM10, and SETD2) exhibiting gender differences. Finally, we discovered co-mutated gene pairs and TP53 p.R282W mutations related to treatment outcomes, highlighting their gender-specific differences.ConclusionThis study identified several molecular biomarkers related to cancer immunotherapy outcomes in terms of mutational signatures, molecular subtypes, and mutated genes, and explored their gender-relatedness in order to provide clues and basis for clinical treatment efficacy evaluation and patient selection.

Tumor organoids improve mutation detection of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) presents challenges in detecting somatic mutations due to its complex cellular composition. This study investigated the utility of patient-derived organoids (PDOs) to overcome these obstacles and enhance somatic mutation identification. Surgically resected PDAC tumors and their paired PDOs from 21 patients were examined. Whole-exome sequencing (WES) of tumor tissue, organoids, and peripheral blood mononuclear cells was performed to identify somatic mutations. Our findings demonstrate that PDOs retained about 80% of the somatic mutations from the original tumors, showing high concordance in mutation types. PDOs exhibited increased tumor purity and uncovered key driver mutations, aiding in identifying clinically relevant genomic alterations. Moreover, eight cycles of FOLFIRINOX treatment did not significantly alter the mutational landscape at the DNA level, indicating the stability of the mutational profile after therapeutic pressure in patients. In conclusion, PDOs are potentially important tools for exploring the somatic mutational landscape of PDAC. While they can reveal mutations that may be challenging to detect through traditional biopsy sequencing due to the inherently low tumor purity of PDAC, it is important to note that PDOs may not always fully recapitulate all mutations found in primary tumors. Despite this limitation, PDOs can still offer critical insights into the genomic complexities of PDAC, which is crucial for the development of personalized vaccines and therapies for this disease.

Somatic mutation rates scale with time not growth rate in long-lived tropical trees

The rates of appearance of new mutations play a central role in evolution. However, mutational processes in natural environments and their relationship with growth rates are largely unknown, particular in tropical ecosystems with high biodiversity. Here, we examined the somatic mutation landscapes of two tropical trees, Shorea laevis (slow-growing) and S. leprosula (fast-growing), in central Borneo, Indonesia. Using newly constructed genomes, we identified a greater number of somatic mutations in tropical trees than in temperate trees. In both species, we observed a linear increase in the number of somatic mutations with physical distance between branches. However, we found that the rate of somatic mutation accumulation per meter of growth was 3.7-fold higher in S. laevis than in S. leprosula. This difference in the somatic mutation rate was scaled with the slower growth rate of S. laevis compared to S. leprosula, resulting in a constant somatic mutation rate per year between the two species. We also found that somatic mutations are neutral within an individual, but those mutations transmitted to the next generation are subject to purifying selection. These findings suggest that somatic mutations accumulate with absolute time and older trees have a greater contribution towards generating genetic variation.

Somatic mutation rates scale with time not growth rate in long-lived tropical trees.

The rates of appearance of new mutations play a central role in evolution. However, mutational processes in natural environments and their relationship with growth rates are largely unknown, particular in tropical ecosystems with high biodiversity. Here, we examined the somatic mutation landscapes of two tropical trees, Shorea laevis (slow-growing) and S. leprosula (fast-growing), in central Borneo, Indonesia. Using newly constructed genomes, we identified a greater number of somatic mutations in tropical trees than in temperate trees. In both species, we observed a linear increase in the number of somatic mutations with physical distance between branches. However, we found that the rate of somatic mutation accumulation per meter of growth was 3.7-fold higher in S. laevis than in S. leprosula. This difference in the somatic mutation rate was scaled with the slower growth rate of S. laevis compared to S. leprosula, resulting in a constant somatic mutation rate per year between the two species. We also found that somatic mutations are neutral within an individual, but those mutations transmitted to the next generation are subject to purifying selection. These findings suggest that somatic mutations accumulate with absolute time and older trees have a greater contribution towards generating genetic variation.

Functional landscape of genome-wide postzygotic somatic mutations between monozygotic twins.

Monozygotic (MZ) twins originate from a single fertilized egg, making them genetically identical at the time of conception. However, postzygotic somatic mutations (PZMs) can introduce genetic differences after separation. Although whole-genome sequencing (WGS) sheds light on somatic mutations in cancer genomics, its application in genomic studies of MZ twins remains limited. In this study, we investigate PZMs in 30 healthy MZ twin pairs from the Osaka University Center for Twin Research using WGS (average depth = 23.8) and a robust germline-calling algorithm. We find high genotype concordance rates (exceeding 99%) in MZ twins. We observe an enrichment of PZMs with variant allele frequency around 0.5 in twins with highly concordant genotypes. These PZMs accumulate more frequently in non-coding regions compared with protein-coding regions, which could potentially influence gene expression. No significant association is observed between the number of PZMs and age or sex. Direct sequencing confirms a missense mutation in the ANKRD35 gene among the PZMs. By applying a genome-wide mutational signature pattern technique, we detect an age-related clock-like signature in these early postzygotic somatic mutations in MZ twins. Our study provides insights that contribute to a deeper understanding of genetic variation in MZ twins.

Deregulation and Shattering of Chromosomal Segments Containing Multiple Oncogenic Targets in the Pathogenesis of Diffuse Large B Cell Lymphoma, Not Otherwise Specified (DLBCL, NOS)

Diffuse large B cell lymphoma, not otherwise specified (DLBCL, NOS) is the most common type of non-Hodgkin lymphoma (NHL). Significant efforts have been focused on utilizing advanced genomic technologies to further subclassify DLBCL, NOS into clinically relevant subtypes. These efforts have led to the implementation of novel algorithms to support optimal risk-oriented therapy and improvement in the overall survival of DLBCL patients. The pathogenesis of DLBCL at the molecular level indicates copy number variation (CNV) as one of the major forms of genetic alterations in the somatic mutational landscape. Random deregulation that results in complex breaks of chromosomes and restructuring of shattered chromosomal segments is called chromothripsis. Gene expression changes influenced by chromothripsis have been reported in cancer and congenital diseases. This chaotic phenomenon results in complex CNV, gene fusions, and amplification and loss of tumor suppressor genes. We present herein a summary of the most clinically relevant genomic aberrations, with particular focus on copy number aberrations in a case that highlights DLBCL, NOS arising from relapsed Hodgkin lymphoma. The focus of our study was to understand the relationship between the clinical, morphological, and genomic abnormalities in DLBCL, NOS through multiple techniques for therapeutic considerations.

The NF1 gene mutations and co-mutations in lung adenocarcinomas with brain metastasis.

The co-occurrence of lung adenocarcinoma and brain metastasis remains a significant cause of morbidity and mortality despite advancements in cancer treatment. The activity of neurofibromin, the product of Neurofibromatosis Type 1 gene (NF1), is crucial in regulating the RAS/MAPK pathway. The NF1 somatic mutations are significant in conditions such as melanoma, lung cancer, breast cancer, neuroblastoma, and central nervous system tumors. Therefore, this research aims to uncover the profile of NF1 mutations and co-mutations in patients with brain metastases from lung adenocarcinoma, shedding light on their role in the pathophysiology of metastatic lung cancer. In this study, a total of 131 (31 females, 90 males) patients diagnosed with metastatic lung adenocarcinoma who were examined in the Molecular Pathology Laboratory between 2019 and 2022 were retrospectively analyzed. The NF1 somatic mutations and co-mutations were evaluated using the NGS lung panel on the MiniSEQ NGS platform. The average age of the 131 patients (31 females, 90 males) retrospectively examined in the study was 62.05 years. The ages of the cases included in the study followed a normal distribution according to Kolmogorov-Smirnov test (P = 0.200). Lymph node metastasis was detected in 48 patients (36.6%), while distant organ metastasis was observed in 81 patients (61.83%). Metastases were more frequently seen in males. No statistically significant difference was found between metastases and gender (P > 0.05). Distant organ metastasis (n = 26, 19.8%) and NF1 mutations (n = 8/26, 30.77%) were most commonly observed in the brain. The most common NF1 pathogenic variants in brain metastases were c.2325 + 3A > G (p.M1205fs*12) (n = 6/26, 23.07%) and c.1400C > T (p.T4671) (n = 5/26, 19.23%). There was no statistically significant relationship observed between patients' age, gender, brain metastasis, and NF1 mutation types (respectively, P = 0.98, P = 0.63, and P = 0.87). The mutations that showed the most association with NF1 mutations in brain metastases were PTEN and TP53. Somatic NF1 mutations and co-mutations can play a critical driving force in metastatic lung adenocarcinoma and may contribute to treatment resistance. The mutational landscape of somatic NF1 mutations and co-mutations can provide new insights into the pathophysiology of metastatic lung cancer, especially those that have metastasized to the brain.

1O The somatic mutation landscape of the normal and malignant pancreas

1O The somatic mutation landscape of the normal and malignant pancreas

The landscape of somatic mutations in human atherosclerotic plaques indicates the presence of large clonal cell populations

The landscape of somatic mutations in human atherosclerotic plaques indicates the presence of large clonal cell populations

Somatic mutational landscape across Indian breast cancer cases by whole exome sequencing

Breast cancer (BC) has emerged as the most common malignancy among females. The genomic profile of BC is diverse in nature and complex due to heterogeneity among various geographically different ethnic groups. The primary objective of this study was to carry out a comprehensive mutational analysis of Indian BC cases by performing whole exome sequencing. The cohort included patients with a median age of 48 years. TTN, TP53, MUC16, SYNE1, and OBSCN were the frequently altered genes found in our cohort. The PIK3CA and KLC3 genes are driver genes implicated in various cellular functions and cargo transportation through microtubules, respectively. Except for CCDC168 and PIK3CA, several gene pairings were found to be significantly linked with co-occurrence. Irrespective of their hormonal receptor status, RTK/RAS was observed with frequently altered signaling pathways. Further analysis of the mutational signature revealed that SBS13, SBS6, and SBS29 were mainly observed in our cohort. This study supplements the discovery of diagnostic biomarkers and provides new therapeutic options for the improved management of BC.

The genomic landscape of 2,023 colorectal cancers

Colorectal carcinoma (CRC) is a common cause of mortality1, but a comprehensive description of its genomic landscape is lacking2–9. Here we perform whole-genome sequencing of 2,023 CRC samples from participants in the UK 100,000 Genomes Project, thereby providing a highly detailed somatic mutational landscape of this cancer. Integrated analyses identify more than 250 putative CRC driver genes, many not previously implicated in CRC or other cancers, including several recurrent changes outside the coding genome. We extend the molecular pathways involved in CRC development, define four new common subgroups of microsatellite-stable CRC based on genomic features and show that these groups have independent prognostic associations. We also characterize several rare molecular CRC subgroups, some with potential clinical relevance, including cancers with both microsatellite and chromosomal instability. We demonstrate a spectrum of mutational profiles across the colorectum, which reflect aetiological differences. These include the role of Escherichiacolipks+ colibactin in rectal cancers10 and the importance of the SBS93 signature11–13, which suggests that diet or smoking is a risk factor. Immune-escape driver mutations14 are near-ubiquitous in hypermutant tumours and occur in about half of microsatellite-stable CRCs, often in the form of HLA copy number changes. Many driver mutations are actionable, including those associated with rare subgroups (for example, BRCA1 and IDH1), highlighting the role of whole-genome sequencing in optimizing patient care.

ERCC2 mutations alter the genomic distribution pattern of somatic mutations and are independently prognostic in bladder cancer

Excision repair cross-complementation group 2 (ERCC2) encodes the DNA helicase xeroderma pigmentosum group D, which functions in transcription and nucleotide excision repair. Point mutations in ERCC2 are putative drivers in around 10% of bladder cancers (BLCAs) and a potential positive biomarker for cisplatin therapy response. Nevertheless, the prognostic significance directly attributed to ERCC2 mutations and its pathogenic role in genome instability remain poorly understood. We first demonstrated that mutant ERCC2 is an independent predictor of prognosis in BLCA. We then examined its impact on the somatic mutational landscape using a cohort of ERCC2 wild-type (n= 343) and mutant (n= 39) BLCA whole genomes. The genome-wide distribution of somatic mutations is significantly altered in ERCC2 mutants, including T[C>T]N enrichment, altered replication time correlations, and CTCF-cohesin binding site mutation hotspots. We leverage these alterations to develop a machine learning model for predicting pathogenic ERCC2 mutations, which may be useful to inform treatment of patients with BLCA.

Whole genome sequencing refines stratification and therapy of patients with clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most common form of kidney cancer, but a comprehensive description of its genomic landscape is lacking. We report the whole genome sequencing of 778 ccRCC patients enrolled in the 100,000 Genomes Project, providing for a detailed description of the somatic mutational landscape of ccRCC. We identify candidate driver genes, which as well as emphasising the major role of epigenetic regulation in ccRCC highlight additional biological pathways extending opportunities for therapeutic interventions. Genomic characterisation identified patients with divergent clinical outcome; higher number of structural copy number alterations associated with poorer prognosis, whereas VHL mutations were independently associated with a better prognosis. The observations that higher T-cell infiltration is associated with better overall survival and that genetically predicted immune evasion is not common supports the rationale for immunotherapy. These findings should inform personalised surveillance and treatment strategies for ccRCC patients.

Multi-omics data analysis reveals the complex roles of age in differentiated thyroid cancer

AimsAge is a major risk factor for differentiated thyroid cancer (DTC); however, the mechanisms underlying aging-regulated progression of DTC remains unclear. MethodsBased on multi-omics data (transcriptional files, somatic mutation files, methylation files) derived from the TCGA database, we comprehensively investigated the genomic and biological features associated with aging in patients with DTC. ResultsWe confirmed that age was an independent risk factor for overall survival and progression-free survival of patients with DTC, and confirmed that 55 years of age (adopted in the 8th AJCC staging system) is an appropriate cutoff for patients with DTC rather than 45 years (adopted in the 7th AJCC staging system). Using 55 years as the cutoff, we demonstrated DNA methylation-driven transcriptional regulation during aging, and identified the landscape of somatic mutations in young and old patients with DTC along with two aging-related mutations: TTN and EIF1AX. Subsequently, we investigated the infiltration of immune cells in DTC, and found that old patients exhibited decreased CD8+ T cells infiltration with lower cytotoxicity. Finally, we constructed a prognosis prediction model based on three age-related genes (PTK2B, E2F1, and GHR) that showed satisfactory performance in predicting patients prognosis. ConclusionsWe comprehensively investigated the complex interplay between age and biological features of DTC, which may provide new insights into the role of aging in DTC.

A pan-cancer analysis of SMARCA4 alterations and the unique clinicogenomic characteristics associated with SMARCA4 mutation types.

3073 Background: SWI/SNF complexes are regulators of cell lineage and alterations in these proteins occur in >20% of solid tumors with SMARCA4being the most common. SMARCA4 mutations are associated with worse clinical outcomes in various cancer types but are also vulnerable to novel SMARCA2 inhibitors currently being evaluated in clinical trials. We examined SMARCA4 alterations across cancer types to understand their interplay with other genomic abnormalities and clinical consequences. Methods: We analyzed the Memorial Sloan Kettering (MSK) institutional cohort profiled by MSK-IMPACT tumor-normal sequencing. SMARCA4 mutations were annotated based on OncoKB and literature. FACETS resolved zygosity and genomic metrics of complexity including tumor mutational burden (TMB) and fraction genome altered (FGA). The pan-cancer landscape of somatic SMARCA4 mutations was mapped by both category (Class I vs II) and zygosity (mono- vs biallelic). DISCOVER was employed to evaluate mutational signatures and frequency-adjusted co-occurring and mutually exclusive mutations. We then extracted progression-free (PFS) and overall survival (OS) to systemic therapy using natural language processing. Results: We identified 3,385 tumors from 3,049 patients across cancer types with a total 3,965 oncogenic somatic SMARCA4 alterations. Copy number estimation was successful for 2,343 (69%). Non-small cell lung cancer (NSCLC) was the most abundant SMARCA4-altered histology ( n=493, 7.1% of all NSCLC), and the majority (87%) were biallelic. Other common histologies were colorectal ( n=163, 2.9%), bladder ( n=122, 5.5%), uterine ( n=88, 4.3%), pancreatic ( n=81, 3.2%) and esophagogastric ( n=92, 4%). SMARCA4biallelic mutated tumors had higher chromosomal instability compared to WT (FGA = 0.53 vs 0.47; p<0.001), while monoallelic had lower (FGA = 0.3; p<0.001). Monoallelic SMARCA4 altered tumors had a higher TMB (10.5) than both WT (4.4) and biallelic cancers (6.1; p<0.001). Monoallelic and biallelic SMARCA4 cancers exhibited distinct mutational signatures in most tumor types. Patients with biallelic SMARCA4 mutations had worse outcomes with both immune checkpoint blockade (ICB) and platinum chemotherapy across in certain tumor types, whereas monoallelic uterine cancers were associated with improved outcomes with ICB. Conclusions: This pan-cancer clinicogenomic analysis demonstrates that monoallelic and biallelic SMARCA4-mutated tumors have distinguishable genomic features. In addition, biallelic SMARCA4 alterations correlated with poor outcomes across different cancer-types and classes of therapy, while improved outcomes to ICB in monoallelic SMARCA4alterations were potentially due to higher representation of MSI-H tumors in this subset. Our findings suggest SMARCA4 zygosity may be important biomarkers for ongoing clinical trials in SMARCA4-deficient tumors.

Comprehensive genomic and transcriptomic profiling of pulmonary nodules in synchronous multiple primary lung cancer.

e20022 Background: Synchronous Multiple Primary Lung Cancer (sMPLC) exhibits distinct histopathological characteristics among pulmonary nodules. However, a comprehensive understanding of the somatic mutation landscape and transcriptome heterogeneity is lacking. Therefore, our study aims to meticulously investigate genomic distinctions among multiple pulmonary nodules within individual patients. Methods: We performed targeted sequencing on tumor specimens and conducted bulk RNA transcriptome analysis on 53 multiple nodules originating from 26 lung cancer patients. The multiple nodules from the same patient was determined as major nodule and minor nodule. Additionally, the tumor tissues underwent histopathological evaluation through H&E staining, complemented by a comprehensive series of immunohistochemistry (IHC) analyses to detect protein expression. The detected protein markers encompassed PD-L1, Ki67, and others. Results: For the 53 nodule samples from 26 MPLCs patients, EGFR was the mostly mutated genes, and the TP53 mutation frequency demonstrated notably different between major and minor nodules. Furthermore, pathway enrichment analysis based on the differentially expressed genes (DEGs) between major and minor nodules revealed the significantly active cell cycle and p53 pathways in the major nodules. Additionally, both major and minor nodules demonstrated mostly similar immune microenvironment and PD-L1 protein expression, and a significantly higher expression of Ki67. A noteworthy suppression was observed in the immune microenvironment in nodules, revealed by the expression of macrophage, neutrophils, and NK cells. Furthermore, minor nodules exhibited a modestly elevated expression of macrophages compared to major nodules. Additionally, among the significantly up-regulated cell cycle related genes in the major nodules when compared with minor nodules, CCNE1 mRNA expression demonstrated significant correlation with poor prognosis in the lung cancer. Conclusions: This study validated molecular distinctions between samples from major and minor nodules in patients with sMPLC at both genomic and transcriptomic levels. The major nodules exhibited heightened activity in tumor cell proliferation pathways and demonstrated malignancy-related biological characteristics, which correlated with pathological assessment results.

Abstract PO1-13-05: Genomic characteristics and its therapeutic implications in breast cancer patients with detectable molecular residual disease

Abstract Background: Breast cancer constitutes approximately 30% of cancers in women, with a mortality-to-incidence ratio of 15%. While early and middle-stage breast cancer patients can undergo radical surgical resection, postoperative recurrence remains a significant challenge for clinicians. Molecular residual disease (MRD) is the main cause of postoperative recurrence of breast cancer. However, the baseline tumor genomic characteristics and therapeutic implications of breast cancer patients with detectable MRD are still unknown. Methods: In this study, we enrolled 80 patients with breast cancer who underwent next-generation sequencing (NGS)-based genetic testing of 1,021 cancer-related genes performed on baseline tumor and postoperative plasma from Army Specialty Medical Center between June 2017 and January 2023. The criteria for the patient’s enrollment were: (1) pathological diagnosis as breast cancer, (2) no distal metastasis, (3) radical surgery and R0 resection, (4) 1021 cancer-related gene testing of the tumor, (5) plasma MRD testing performed within 3 months after surgery and before adjuvant therapy. Results: A total of 18 patients in our cohort had detectable MRD. Baseline clinical characteristics found that patients with higher clinical stages were more likely to have detectable MRD. Analysis of single nucleotide variations and small insertions/deletions in baseline tumors showed that somatic mutations in MAP3K1, ATM, FLT1, GNAS, POLD1, SPEN, and WWP2 were significantly enriched in patients with postoperative MRD. Oncogenic signaling pathway analysis revealed that alteration of the Cell cycle pathway was more likely to occur in patients with detectable MRD (p=0.0125). Mutational signature analysis showed that defective DNA mismatch repair and activation-induced cytidine deaminase (AID) mediated somatic hypermutation (SHM) were associated with detectable MRD. Somatic copy number variation analysis found that amplification of CDKN2A, HOXB13, PPM1D, MPL, and VHL was significantly enriched in patients with detectable MRD. According to the OncoKB database, 77.8% (14/18) of patients with detectable MRD had U.S. Food and Drug Administration-approved mutational biomarkers and targeted therapy. Conclusion: For the first time, our study reports genomic characteristics of breast cancer patients with detectable MRD. The tumor biology is probably the main driver of detectable MRD. We also found the vast majority of patients with detectable MRD have the opportunity to access targeted therapy. Keywords: Breast cancer, MRD, Genomic character, Cell cycle pathway, Defective DNA mismatch repair, Activation-induced cytidine deaminase Figure 1. Somatic mutational landscape and clinical actionability of breast cancer patients with detectable MRD A. Oncoplot of top 20 genes altered in patients with detectable MRD. B. Forest plot of different mutant genes between patients with detectable and undetectable MRD. OR means odds ratio. Inf means infinity. ＊ means P-value < 0.05. C. The ten cancer-related signaling pathways were affected by somatic mutations both in patients with detectable and undetectable MRD. ＊ means P-value < 0.05. D&E. The fraction and etiology of each signature in patients with detectable (D) or undetectable (E) MRD. F. The number of patients with detectable MRD in different actionable alterations. gBRCA1 means germline BRCA1 mutation. sBRCA1 means somatic BRCA1 mutation. sBRCA2 means somatic BRCA2 mutation. TMB-H means TMB-High. Citation Format: Xu Yan, Shu Zhang, Lu zhou, Yan Jiang, Jing Xu, Gang Zhang, Lu Shen. Genomic characteristics and its therapeutic implications in breast cancer patients with detectable molecular residual disease [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 PO1-13-05.

Abstract PO1-15-11: Molecular and clinical disparities in breast cancer among East Asian populations

Abstract Background Breast Cancer (BC) is a complex disease with profound genomic aberrations. However, the underlying molecular disparity influenced by age and ethnicity remains elusive. Method We aimed to investigate the molecular properties of 843 primary and metastatic BC patients enrolled in the K-MASTER program. We explored the unique molecular profiles of breast cancer patients by categorizing them into two distinct age subgroups. The first subgroup comprised young breast cancer (YBC) patients, defined as women under the age of 40, while the second subgroup consisted of older breast cancer (OBC) patients. Our study aimed to characterize the molecular differences between these age-defined groups, providing insights into the underlying mechanisms of breast cancer in different age cohorts. Additionally, we leveraged large-scale genomic data from the TCGA and MSK-IMPACT studies to examine the ethnic-driven molecular and clinical disparities. Results The K-MASTER patients were mainly comprised of triple-negative breast cancer (TNBC) and HER2-positive tumors, while the TCGA and MSK-IMPACT cohorts exhibited a predominance of hormone receptor-positive (HR+) subtype. We observed a high prevalence of PI3KCA mutations in K-MASTER HER2+ tumors, particularly in older patients. Moreover, we identified increased mutation rates in DNA damage response molecules, including ARID1A, MSH6, and MLH1. Importantly, GATA3 mutations were less frequently observed in East Asian patients, which correlated with poor clinical outcomes. Our analysis also revealed specific associations between genomic aberrations, organotropisms, and metastatic breast cancer. In addition to characterizing the molecular disparities, we developed a gradient-boosting multivariable model to identify a new molecular signature that could predict the therapeutic response to platinum-based chemotherapy. Conclusion Our findings collectively provide unprecedented insights into the significance of age and ethnicity on the molecular and clinical characteristics of BC patients. Figure 1. Genomic landscape of KM BRCA. (A) Overall characteristic of KM BRCA sample and clinical data. Clinical features of KM BRCA sample. (B) Genomic landscape of somatic mutations and copy number alterations of BRCA by age group. Figure 2. Genomic landscape of KM BRCA: Significantly mutated genes by age group in KM BRCA. Figure 3. Survival Curve Utilizing a curated Gene Set Developed by a Gradient-Boosting Multivariable Model (A) OS of platinum-based therapy treated KM with curated Gene set. (B) OS of platinum-based therapy treated MSK with curated Gene set. Citation Format: Kim Ju Won, LEE JIWON, Kyong Hwa Park, Seung Pil Jung, Jason Sa, SHIN SANG WON, An Jung Seok. Molecular and clinical disparities in breast cancer among East Asian populations [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 PO1-15-11.

Diffuse large B-cell lymphoma with DNA copy number changes in a Japanese black calf

A 2-month-old Japanese Black calf exhibited mandibular and superficial cervical lymph node swelling. Fine needle aspiration cytology of the superficial cervical lymph node revealed large lymphoblast-like cells with mitoses. Hematological examination revealed remarkable lymphocytosis with atypical lymphocytes. Increased activities of serum total lactate dehydrogenase and thymidine kinase were detected. At necropsy, generalized swelling of lymph nodes was observed. Histopathological analysis revealed diffuse proliferation of medium-sized round centroblastic neoplastic cells that were positive for CD20, CD79α, PAX5, and BLA-36, and negative for CD3, CD5, CD10, and CD34. The calf was diagnosed with centroblastic diffuse large B-cell lymphoma (DLBCL) based on these findings. Analysis of DNA copy number variation revealed an increased copy number for the GIMAP family relative to that in healthy cattle. Moreover, decreases in copy numbers of GBP-1, MIR3141, OR5P1E, and PTPRG relative to those in healthy cattle were also observed. Because DNA copy number variation represent a major contribution to the somatic mutation landscapes in human tumors, these findings suggest that DNA copy number changes might have contributed to the onset of DLBCL in the present case.

Abstract 7292: Surveying the landscape of somatic variation in healthy breast tissue for cancer risk prediction

Abstract Carcinogenesis centers on principles of somatic evolution, where a cell gradually accumulates mutations, eventually transforming into a tumor cell. Exploring somatic variation in the healthy population offers insights for predicting cancer risk and facilitating early detection. In breast cancer (BC), the emergence of the malignant clone occurs within a broader spectrum of abnormal cells, often referred to as the 'field effect.' BC development is intricately linked to hormonal regulation, with prior research indicating that the initial changes manifest during puberty and pregnancy. Although around 10% of diagnosed BCs affect young women (<45 years), with 35-55% of these cases arising within a decade after completed pregnancy (postpartum BC), effective screening tools are lacking. We propose a novel approach for the individualized quantification of somatic variation and the field effect using breast milk (BM) as a liquid biopsy. We conducted a retrospective analysis of 272 BM samples obtained from both the left and right breasts of 125 healthy donors, including 62 donors with elevated cancer risk due to a germline predisposition involving BRCA. Given the heterogeneous cellular composition of BM, encompassing epithelial cells and lymphocytes, we initially implemented a comprehensive analysis to reliably detect somatic mutations in whole BM, as well as in magnetically activated cell-sorted (MACS) epithelial-enriched (EE) and -depleted (ED) samples from a subset of donors. DNA extracted from all samples was used for NanoSeq, a single-molecule sequencing methodology, focusing on a targeted panel of 84 genes recognized as drivers in either BC or normal tissue. Our assessment of mutation burden estimates across all sample types revealed consistent results. Generally, cells accumulated somatic mutations linearly with age, but with a higher rate in individuals with a BRCA2 cancer predisposition. We found several critical driver genes, including PIK3CA, PIK3R1, TP53, to be under significant positive selection using the ratio of non-synonymous to synonymous mutations. When we assessed the fraction of cells in each sample carrying mutations in these genes, we however detected a significantly higher fraction of mutated cells in individuals with germline predisposition - possibly representing a genetic manifestation of the epidemiologically higher risk of BRCA germline carriers. As we expand our understanding of the interplay between the somatic mutation landscape and cancer risk, our efforts provide evidence for the utility of BM as an easily accessible, non-invasive sample. The proposed methodology, involving BM with precise genetic analysis through NanoSeq, presents a promising avenue for elucidating personalized somatic variation patterns. We anticipate that BM holds potential as a valuable tool for risk stratification, particularly for individuals under 45 and postpartum women. Citation Format: Moritz Jakob Przybilla, Andrew R. Lawson, Pantelis Nicola, Brian T. Pentecost, Inigo Martincorena, Kathleen F. Arcaro, Peter J. Campbell. Surveying the landscape of somatic variation in healthy breast tissue for cancer risk prediction [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 7292.