Distinct Mutational Landscape Research Articles

The K9 lymphoma assay allows a genetic subgrouping of canine lymphomas with improved risk classification

We present here the K9 lymphoma assay, a novel 31-gene targeted next-generation sequencing panel designed for genomic profiling of canine lymphoid neoplasms. Addressing the growing demand for advanced diagnostics in veterinary oncology, this assay enables sensitive identification of known and actionable mutations specific to canine lymphomas, while evaluating its prognostic potential to facilitate diagnosis and prognosis. Our analysis, spanning several B- and T-cell lymphoma histotypes, unveiled distinct mutational landscapes distinguishing tumors derived from immature versus mature lymphocytes. Clustering analysis revealed a shared genetic origin between diffuse large B-cell lymphoma and marginal zone lymphoma, aligning with findings in human lymphomas, with TRAF3 emerging as the most frequently mutated gene across B-cell lymphoma subtypes. Significantly, TP53 mutations demonstrated universal adverse prognostic implications across B-cell lymphomas. Additionally, SETD2 mutations contributed to shorter time-to-progression, underscoring the role of epigenetic dysregulation in B-cell tumors. In T-cell lymphomas, SATB1 and FBXW7 were frequently mutated, warranting further investigation in larger cohorts. Our findings advocate for tailored therapeutic approaches based on the genetic profile, impacting treatment decisions and outcomes in canine lymphoma management. This study provides pivotal insights bridging veterinary and human oncology, paving the way for comprehensive genomic diagnostics and therapeutic strategies in comparative oncology.

Single-mitochondrion sequencing uncovers distinct mutational patterns and heteroplasmy landscape in mouse astrocytes and neurons

BackgroundMitochondrial (mt) heteroplasmy can cause adverse biological consequences when deleterious mtDNA mutations accumulate disrupting “normal” mt-driven processes and cellular functions. To investigate the heteroplasmy of such mtDNA changes, we developed a moderate throughput mt isolation procedure to quantify the mt single-nucleotide variant (SNV) landscape in individual mouse neurons and astrocytes. In this study, we amplified mt-genomes from 1645 single mitochondria isolated from mouse single astrocytes and neurons to (1) determine the distribution and proportion of mt-SNVs as well as mutation pattern in specific target regions across the mt-genome, (2) assess differences in mtDNA SNVs between neurons and astrocytes, and (3) study co-segregation of variants in the mouse mtDNA.Results(1) The data show that specific sites of the mt-genome are permissive to SNV presentation while others appear to be under stringent purifying selection. Nested hierarchical analysis at the levels of mitochondrion, cell, and mouse reveals distinct patterns of inter- and intra-cellular variation for mt-SNVs at different sites. (2) Further, differences in the SNV incidence were observed between mouse neurons and astrocytes for two mt-SNV 9027:G > A and 9419:C > T showing variation in the mutational propensity between these cell types. Purifying selection was observed in neurons as shown by the Ka/Ks statistic, suggesting that neurons are under stronger evolutionary constraint as compared to astrocytes. (3) Intriguingly, these data show strong linkage between the SNV sites at nucleotide positions 9027 and 9461.ConclusionsThis study suggests that segregation as well as clonal expansion of mt-SNVs is specific to individual genomic loci, which is important foundational data in understanding of heteroplasmy and disease thresholds for mutation of pathogenic variants.

Single-Mitochondrion Sequencing Uncovers Distinct Mutational Patterns and Heteroplasmy Landscape in Mouse Astrocytes and Neurons.

Mitochondrial (mt) heteroplasmy can cause adverse biological consequences when deleterious mtDNA mutations accumulate disrupting 'normal' mt-driven processes and cellular functions. To investigate the heteroplasmy of such mtDNA changes we developed a moderate throughput mt isolation procedure to quantify the mt single-nucleotide variant (SNV) landscape in individual mouse neurons and astrocytes In this study we amplified mt-genomes from 1,645 single mitochondria (mts) isolated from mouse single astrocytes and neurons to 1. determine the distribution and proportion of mt-SNVs as well as mutation pattern in specific target regions across the mt-genome, 2. assess differences in mtDNA SNVs between neurons and astrocytes, and 3. Study cosegregation of variants in the mouse mtDNA. 1. The data show that specific sites of the mt-genome are permissive to SNV presentation while others appear to be under stringent purifying selection. Nested hierarchical analysis at the levels of mitochondrion, cell, and mouse reveals distinct patterns of inter- and intra-cellular variation for mt-SNVs at different sites. 2. Further, differences in the SNV incidence were observed between mouse neurons and astrocytes for two mt-SNV 9027:G>A and 9419:C>T showing variation in the mutational propensity between these cell types. Purifying selection was observed in neurons as shown by the Ka/Ks statistic, suggesting that neurons are under stronger evolutionary constraint as compared to astrocytes. 3. Intriguingly, these data show strong linkage between the SNV sites at nucleotide positions 9027 and 9461. This study suggests that segregation as well as clonal expansion of mt-SNVs is specific to individual genomic loci, which is important foundational data in understanding of heteroplasmy and disease thresholds for mutation of pathogenic variants.

Genomic characterization reveals distinct mutational landscapes and therapeutic implications between different molecular subtypes of triple-negative breast cancer

Triple-negative breast cancer (TNBC) has high heterogeneity, poor prognosis, and limited treatment success. Recently, an immunohistochemistry-based surrogate classification for the “Fudan University Shanghai Cancer Center (FUSCC) subtyping” has been developed and is considered more suitable for clinical application. Seventy-one paraffin-embedded sections of surgically resected TNBC were classified into four molecular subtypes using the IHC-based surrogate classification. Genomic analysis was performed by targeted next-generation sequencing and the specificity of the subtypes was explored by bioinformatics, including survival analysis, multivariate Cox regression, pathway enrichment, Pyclone analysis, mutational signature analysis and PHIAL analysis. AKT1 and BRCA1 mutations were identified as independent prognostic factors in TNBC. TNBC molecular subtypes encompass distinct genomic landscapes that show specific heterogeneities. The luminal androgen receptor (LAR) subtype was associated with mutations in PIK3CA and PI3K pathways, which are potentially sensitive to PI3K pathway inhibitors. The basal-like immune-suppressed (BLIS) subtype was characterized by high genomic instability and the specific possession of signature 19 while patients in the immunomodulatory (IM) subtype belonged to the PD-L1 ≥ 1% subgroup with enrichment in Notch signaling, suggesting a possible benefit of immune checkpoint inhibitors and Notch inhibitors. Moreover, mesenchymal-like (MES) tumors displayed enrichment in the receptor tyrosine kinase (RTK)-RAS pathway and potential sensitivity to RTK pathway inhibitors. The findings suggest potential treatment targets and prognostic factors, indicating the possibility of TNBC stratified therapy in the future.

Integrative analysis of senescence-related genes identifies robust prognostic clusters with distinct features in hepatocellular carcinoma

IntroductionSenescence refers to a state of permanent cell growth arrest and is regarded as a tumor suppressive mechanism, whereas accumulative evidence demonstrate that senescent cells play an adverse role during cancer progression. The scarcity of specific and reliable markers reflecting senescence level in cancer impede our understanding of this biological basis. ObjectivesSenescence-related genes (SRGs) were collected for integrative analysis to reveal the role of senescence in hepatocellular carcinoma (HCC). MethodsConsensus clustering was used to subtype HCC based on SRGs. Several computational methods, including single sample gene set enrichment analysis (ssGSEA), fuzzy c-means algorithm, were performed. Data of drug sensitivities were utilized to screen potential therapeutic agents for different senescence patients. Additionally, we developed a method called signature-related gene analysis (SRGA) for identification of markers relevant to phenotype of interest. Experimental strategies consisting quantitative real-time PCR (qRT-PCR), β-galactosidase assay, western blot, and tumor-T cell co-culture system were used to validate the findings in vitro. ResultsWe identified three robust prognostic clusters of HCC patients with distinct survival outcome, mutational landscape, and immune features. We further extracted signature genes of senescence clusters to construct the senescence scoring system and profile senescence level in HCC at bulk and single-cell resolution. Senescence-induced stemness reprogramming was confirmed both in silico and in vitro. HCC patients with high senescence were immune suppressed and sensitive to Tozasertib and other drugs. We suggested that MAFG, PLIN3, and 4 other genes were pertinent to HCC senescence, and MAFG potentially mediated immune suppression, senescence, and stemness. ConclusionOur findings provide insights into the role of SRGs in patients stratification and precision medicine.

Tri-ing to decipher trisomy AML.

Lam etal. compared trisomy acute myeloid leukaemia (AML) patients (inclusive of single trisomy, double trisomy or tetrasomy cases) with cytogenetically normal AML to uncover distinguishing molecular and prognostic features of trisomy AML. The study contributes to our understanding of trisomy AML, but the heterogeneity of trisomy subtypes remains a barrier to its study. Commentary on: Lam etal. Distinct karyotypic and mutational landscape in trisomy AML. Br J Haematol 2024;204:939-944.

Pan-cancer analysis of HS6ST2: associations with prognosis, tumor immunity, and drug resistance.

In this comprehensive study spanning 33 malignancies, we explored the differential expression and prognostic significance of Heparan sulfate 6-O-sulfotransferase 2 (HS6ST2). TIMER2, UALCAN, and GEPIA2 were used for the expression analysis. cBioPortal was used for mutational analysis. CancerSEA, STRING, and DAVID, were employed for the single cell sequencing data analysis, protein-protein interaction network development, and gene enrichment analyses, respectively. GSCAlite and RT-qPCR were used for drug sensitivity and expression validation analysis. HS6ST2 exhibited significant (P < 0.05) overexpression in multiple cancers. Prognostically, elevated HS6ST2 expression was significantly associated with poor overall survival (OS) in patients with cervical squamous cell carcinoma (CESC), kidney chromophobe (KICH), lung adenocarcinoma (LUAD), and stomach adenocarcinoma (STAD), emphasizing its potential as a prognostic indicator in these cancers. Moreover, HS6ST2 expression correlated with pathological stages in CESC, KICH, LUAD, and STAD patients. Exploration of genetic alterations using cBioPortal unveiled distinct mutational landscapes, with low mutation frequencies in CESC, KICH, LUAD, and STAD. Additionally, reduced DNA methylation in CESC, KICH, LUAD, and STAD suggested a potential link between hypomethylation and heightened HS6ST2 expression. Analysis of immune cell infiltration revealed a positive correlation between HS6ST2 expression and the infiltration of CD8+ T and CD4+ T cells in CESC, KICH, LUAD, and STAD, highlighting its involvement in the tumor immunology processes. Single-cell functional states analysis demonstrated associations between HS6ST2 and diverse cellular processes. Moreover, gene enrichment analysis revealed the involvement HS6ST2 in crucial cellular activities. GSCAlite analysis underscored the potential of HS6ST2 as a therapeutic target, showing associations with drug sensitivity. Finally, experimental validation through reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and immunohistochemistry in LUAD tissues confirmed elevated HS6ST2 expression. Overall, this study provides a comprehensive understanding of HS6ST2 in CESC, KICH, LUAD, and STAD, emphasizing its potential as a prognostic biomarker and therapeutic target.

Distinct karyotypic and mutational landscape in trisomy AML.

Trisomy karyotype occurs in 5%-10% of AML. Its mutational landscape and prognostic significance are not well defined. A cohort of 156 trisomy AML patients was analysed, with reference to 615 cytogenetically normal (CN) AML patients. Trisomy AML showed distinct mutational landscape with more prevalent SMC1A, N/KRAS, ASXL1 and BCOR but fewer CEBPAbZIP and NPM1 mutations in patients ≤60, and fewer NPM1 mutations in those >60. NRAS mutations were associated with poor outcome in trisomy AML, whereas DNMT3A and FLT3-ITD mutations had neutral effect. Trisomy AML appeared biologically distinct from CN-AML.

Association of PIK3CA mutation with outcomes in HER2-positive breast cancer treated with anti-HER2 therapy: A meta-analysis and bioinformatic analysis of TCGA‑BRCA data

BackgroundThis study aimed to comprehensively explore the clinical significance of PIK3CA mutation in human epidermal growth factor receptor 2 (HER2)-positive breast cancer treated with anti-HER2 therapy. MethodsWe systematically searched PubMed, Embase, and the Cochrane databases for eligible studies assessing the association between PIK3CA mutation and outcomes in patients with HER2-positive breast cancer receiving anti-HER2 therapy. The main outcomes included: (1) pathological complete response (pCR) or disease-free survival (DFS) for the neoadjuvant setting; (2) DFS or invasive DFS for the adjuvant setting; (3) objective response rate (ORR), progression-free survival (PFS), time-to-progression (TTP), or overall survival (OS) for the metastatic setting. The mutational landscape of HER2-positive breast cancer according to PIK3CA mutation status was examined based on TCGA breast cancer dataset. ResultsTotally, 43 eligible studies, covering 11,099 patients with available data on PIK3CA mutation status, were identified. In the neoadjuvant setting, PIK3CA mutation was significantly associated with a lower pCR rate (OR=0.23, 95% CI 0.19–0.27, p<0.001). This association remained significant irrespective of the type of anti-HER2 therapy (single-agent or dual-agent) and hormone receptor status. There were no significant differences in DFS between PIK3CA mutated and wild-type patients in either the neoadjuvant or adjuvant settings. In the metastatic setting, PIK3CA mutation predicted worse ORR (OR=0.26, 95%CI 0.17–0.40, p<0.001), PFS (HR=1.28, 95%CI 1.03–1.59, p = 0.024) and TTP (HR=2.27, 95%CI 1.54–3.34, p<0.001). However, no significant association was observed between PIK3CA mutation status and OS. Distinct mutational landscapes were observed in HER2-positive breast cancer between individuals with PIK3CA mutations and those with wild-type PIK3CA. ConclusionsPIK3CA mutation was significantly associated with a lower pCR rate in HER2-positive breast cancer treated with neoadjuvant anti-HER2 therapy. In the metastatic setting, PIK3CA mutation was predictive of worse ORR, PFS and TTP. These results suggest the potential for developing PI3K inhibitors as a therapeutic option for these patients.

Clinico-genetic and prognostic analyses of 716 patients with primary myelodysplastic syndrome and myelodysplastic syndrome/acute myeloid leukemia based on the 2022 International Consensus Classification.

The 2022 International Consensus Classification (ICC) recategorized myeloid neoplasms based on recent advances in the understanding of the biology of hematologic malignancies, in which myelodysplastic syndrome (MDS) with blasts of 10%-19% is classified as MDS/acute myeloid leukemia (AML), MDS with mutated SF3B1, irrespective of the number of ring sideroblasts, as MDS-SF3B1, and those with multi-hit TP53 mutations as MDS with mutated TP53. In the analysis of 716 patients with MDS diagnosed according to the 2016 WHO classification, we found that 75.3% of patients remained in the MDS group based on the ICC, while 24.7% of patients were reclassified to the MDS/AML group after the exclusion of 15 patients who were classified to the AML group. Patients with MDS/AML showed a distinct mutational landscape and had poorer outcomes, compared to those with MDS. In the MDS group, patients with MDS-SF3B1 had higher frequencies of DNMT3A and TET2 mutations than those with MDS, not otherwise specified, with single lineage dysplasia or multilineage dysplasia. Patients with mutated TP53 were associated with dismal outcomes, irrespective of the blast percentage. In conclusion, this study showed that the ICC facilitates efficient segregation and risk-stratification of MDS which can help guide the treatment choice of patients with the disease.

Hallmark-guided subtypes of hepatocellular carcinoma for the identification of immune-related gene classifiers in the prediction of prognosis, treatment efficacy, and drug candidates.

Hepatocellular carcinoma (HCC), accounting for ~90% of all primary liver cancer, is a prevalent malignancy worldwide. The intratumor heterogeneity of its causative etiology, histology, molecular landscape, and immune phenotype makes it difficult to precisely recognize individuals with high mortality risk or tumor-intrinsic treatment resistance, especially immunotherapy. Herein, we comprehensively evaluated the activities of cancer hallmark gene sets and their correlations with the prognosis of HCC patients using gene set variation analysis (GSVA) and identified two HCC subtypes with distinct prognostic outcomes. Based on these subtypes, seven immune-related genes (TMPRSS6, SPP1, S100A9, EPO, BIRC5, PLXNA1, and CDK4) were used to construct a novel prognostic gene signature [hallmark-guided subtypes-based immunologic signature (HGSIS)] via multiple statistical approaches. The HGSIS-integrated nomogram suggested an enhanced predictive performance. Interestingly, oncogenic hallmark pathways were significantly enriched in the high-risk group and positively associated with the risk score. Distinct mutational landscapes and immune profiles were observed between different risk groups. Moreover, immunophenoscore (IPS) and tumor immune dysfunction and exclusion (TIDE) analysis showed different sensitivities of HGSIS risk groups for immune therapy efficacy, and the pRRophetic algorithm indicated distinguishable responses for targeted/chemotherapies in different groups. KIF2C was picked out as the key target concerning HGSIS, and the top 10 small molecules were predicted to bind to the active site of KIF2C via molecular docking, which might be further used for candidate drug discovery of HCC. Taken together, our study offers novel insights for clinically significant subtype recognition, and the proposed signature may be a helpful guide for clinicians to improve the treatment regimens.

Exome sequencing reveals a distinct somatic genomic landscape in breast cancer from women with germline PTEN variants

Germline PTEN variants (PTEN hamartoma tumor syndrome [PHTS]) confer up to 85% lifetime risk of female breast cancer (BC). BCs arising in PHTS are clinically distinct from sporadic BCs, including younger age of onset, multifocality, and an increased risk of second primary BCs. Yet, there is no previous investigation into the underlying genomic landscape of this entity. We sought to address the hypothesis that BCs arising in PHTS have a distinct genomic landscape compared to sporadic counterparts. We performed and analyzed exome sequencing data from 44 women with germline PTEN variants who developed BCs. The control cohort comprised of 497 women with sporadic BCs from The Cancer Genome Atlas (TCGA) dataset. We demonstrate that PHTS-derived BCs have a distinct somatic mutational landscape compared to the sporadic counterparts, namely second somatic hits in PTEN, distinct mutational signatures, and increased genomic instability. The PHTS group had a significantly higher frequency of somatic PTEN variants compared to TCGA (22.7% versus 5.6%; odds ratio [OR] 4.93; 95% confidence interval [CI] 2.21 to 10.98; p<0.001) and a lower mutational frequency in PIK3CA (22.7% versus 33.4%; OR 0.59; 95% CI 0.28 to 1.22; p= 0.15). Somatic variants in PTEN and PIK3CA were mutually exclusive in PHTS (p= 0.01) but not in TCGA. Our findings have important implications for the personalized management of PTEN-related BCs, especially in the context of more accessible genetic testing.

Distinct mutational landscapes characterize melanomas metastatic to different anatomical sites.

9562 Background: Despite revolutionary advances in systemic therapies for melanoma, many patients with metastatic disease have limited treatment options and some sites of disease remain particularly challenging to control, such as brain and liver metastases. We sought to define anatomical site-specific mutational profiles of melanoma metastases from which potentially novel personalized therapeutic opportunities may be developed. Methods: Targeted exome genomic profiling was performed via the FoundationOneCDx platform and known or likely pathogenic variants retained for analysis. PD-L1 immunohistochemistry was performed with the Dako 22C3 assay with PD-L1+ defined as tumor proportion score ≥1. Tumor mutational burden (TMB)-high was defined as TMB ≥10mut/Mb. UV signature was calculated using established algorithms. Aberrations in 23 genes potentially actionable in melanoma ( BARD1, BRAF, BRCA1/2, CDKN2A, DDX3X, FANCC, HRAS, IDH1, KIT, KRAS, MAP2K1, NF1, NRAS, PALB2, PIK3CA, PPP6C, PTEN, RAC1, RAD51C/D, RB1, TP53) were compared across metastatic sites including skin, lymph node, lung, liver, and brain. Results: A total of 4918 cutaneous-type melanoma tumors was evaluated, including 2854 skin lesions (primary/metastasis) and metastases from lymph nodes (n = 858), liver (n = 194), lung (n = 342), and brain (n = 200). The commonly mutated genes were CDKN2A (2220/4918, 45.1%), BRAF (2148/4918, 43.7%), NRAS(1347/4918, 27.4%), NF1 (1038/4918, 21.1%), TP53 (1234/4918, 25.1%) and PTEN (1038/4918, 13.5%). Compared with skin lesions, metastases to the lung were enriched for variants affecting NF1 (OR 2.57, p = 8.99e-13), TP53 (OR 1.65, p = 3.04e-04) and depleted in NRAS (OR 0.49, p = 9.00e-06) and BRAF (OR 0.70, p = 1.13e-02). Lung metastases were associated with higher prevalence of UV signatures, PD-L1 positivity and high TMB. PTEN variants were enriched in both brain (OR 3.00, p = 2.38e-08) and small intestine (OR3.46, p = 6.63e-3) metastases. Brain metastases were also enriched for CDKN2A variants (OR 1.56, p = 4.50e-02). Lymph node metastases had lower rates of UV signatures, NF1 variants, or high TMB, but were associated with PD-L1 positivity. Positional analysis of variants revealed that several, including NRAS, MAP2K1, KRAS, HRAS, IDH1, RAC1, GNA11 and GNAQ were highly restricted to hotspot loci, without definite variation by metastatic site. Conversely, variants affecting CDKN2A, PTEN, TP53 and NF1 were distributed widely across the gene, with high levels of non-hotspot mutations observed in skin lesions, suggesting that such non-hotspot subclones contribute less to distant metastatic potential and are lost during disease evolution. Conclusions: We observed distinct and organ site-specific mutational patterns in patients with metastatic melanoma. These data raise the possibility of metastatic phenotype-directed therapy to improve the personalization and outcomes of treatment for this disease.

S100A2 and the Np63 Network, an overlooked pancreatic cancer drug target

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with an abysmal ~10% survival rate at 5-years. With 48,000 projected deaths in 2021 it is now the third most common cause of cancer death in the USA, and will be number two by 2030. In Australia (2020) there were 3,900 new cases and a staggering 3,300 deaths. Current therapies are palliative at best highlighting the urgent need for novel therapeutic agents targeting molecular phenotypes not responsive to current treatments. The highly heterogeneic and metastatic nature of PDAC presents a major challenge in therapeutic development. Recent integratomic studies have demonstrated that PDAC is composed of two major transcriptomic subtypes - classical (pancreatic) and squamous (or quasi-mesenchymal/basal-like), which are characterised by distinct mutational landscapes. The squamous subtype is associated with gene silencing of endoderm specification genes; metabolic reprogramming; and an extremely poor clinical outcome. The squamous subtype shows significant S100A2 upregulation, and its presence is associated with poor patient prognosis. This has been overlooked in the pancreatic cancer drug development pipeline and offers an unparalleled opportunity to specifically target biomarkers known to be upregulated in PDAC. Importantly, S100A2 is considered a validated PDAC biomarker. We have identified molecular mechanisms that contribute to these aggressive, metastatic subtypes, and are targetable with novel drugs.

Artificial Intelligence–Powered Hematoxylin and Eosin Analyzer Reveals Distinct Immunologic and Mutational Profiles among Immune Phenotypes in Non–Small-Cell Lung Cancer

The tumor microenvironment can be classified into three immune phenotypes: inflamed, immune excluded, and immune-desert. Immunotherapy efficacy has been shown to vary by phenotype; yet, the mechanisms are poorly understood and demand further investigation. This study unveils the mechanisms using an artificial intelligence-powered software called Lunit SCOPE. Artificial intelligence was used to classify 965 samples of non-small-cell lung carcinoma from The Cancer Genome Atlas into the three immune phenotypes. The immune and mutational profiles that shape each phenotype using xCell, gene set enrichment analysis with RNA-sequencing data, and cBioportal were described. In the inflamed subtype, which showed higher cytolytic score, the enriched pathways were generally associated with immune response and immune-related cell types were highly expressed. In the immune excluded subtype, enriched glycolysis, fatty acid, and cholesterol metabolism pathways were observed. The KRAS mutation, BRAF mutation, and MET splicing variant were mostly observed in the inflamed subtype. The two prominent mutations found in the immune excluded subtype were EGFR and PIK3CA mutations. This study is the first to report the distinct immunologic and mutational landscapes of immune phenotypes, and demonstrates the biological relevance of the classification. In light of these findings, the study offers insights into potential treatment options tailored to each immune phenotype.

Comprehensive characterization of CRC with germline mutations reveals a distinct somatic mutational landscape and elevated cancer risk in the Chinese population.

Objective:Hereditary colorectal cancer (CRC) accounts for approximately 5%–10% of all CRC cases. The full profile of CRC-related germline mutations and the corresponding somatic mutational profile have not been fully determined in the Chinese population.Methods:We performed the first population study investigating the germline mutation status in more than 1,000 (n = 1,923) Chinese patients with CRC and examined their relationship with the somatic mutational landscape. Germline alterations were examined with a 58-gene next-generation sequencing panel, and somatic alterations were examined with a 605-gene panel.Results:A total of 92 pathogenic (P) mutations were identified in 85 patients, and 81 likely pathogenic (LP) germline mutations were identified in 62 patients, accounting for 7.6% (147/1,923) of all patients. MSH2 and APC was the most mutated gene in the Lynch syndrome and non-Lynch syndrome groups, respectively. Patients with P/LP mutations had a significantly higher ratio of microsatellite instability, highly deficient mismatch repair, family history of CRC, and lower age. The somatic mutational landscape revealed a significantly higher mutational frequency in the P group and a trend toward higher copy number variations in the non-P group. The Lynch syndrome group had a significantly higher mutational frequency and tumor mutational burden than the non-Lynch syndrome group. Clustering analysis revealed that the Notch signaling pathway was uniquely clustered in the Lynch syndrome group, and the MAPK and cAMP signaling pathways were uniquely clustered in the non-Lynch syndrome group. Population risk analysis indicated that the overall odds ratio was 11.13 (95% CI: 8.289–15.44) for the P group and 20.68 (95% CI: 12.89–33.18) for the LP group.Conclusions:Distinct features were revealed in Chinese patients with CRC with germline mutations. The Notch signaling pathway was uniquely clustered in the Lynch syndrome group, and the MAPK and cAMP signaling pathways were uniquely clustered in the non-Lynch syndrome group. Patients with P/LP germline mutations exhibited higher CRC risk.

Abstract PO-155: Racial heterogeneity in the molecular landscape of pancreatic adenocarcinoma: A call for action

Abstract Background: Pancreatic adenocarcinoma (PDAC) is an aggressive cancer predicted to be the second leading cause of cancer mortality in the next decade. Significant disparities in the incidence rate and outcomes of Black patients with PDAC have recently been reported. Efforts to characterize the molecular landscape of PDAC are ongoing; however, the molecular mechanisms driving cancer in PDAC patients remain largely unexplored with respect to sociocultural race. In this study, we utilized the Cancer Genome Atlas (TCGA) dataset to describe the somatic mutation, DNA methylation and gene expression profiles of PDAC patients with respect to sociocultural race in an effort to elucidate the racial heterogeneity in pancreatic carcinogenesis. Methods: This study involved accessing the public TCGA dataset for all patients with diagnosed PDACs. We filtered this cohort to include only patients with available racial information and matched DNA methylation, mRNA expression and simple somatic mutation data (n = 150). We analyzed the frequency and nature of non-silent simple somatic mutations for our cohort, both combined and separated by sociocultural race, and calculated the top differentially-methylated and differentially-expressed genes, using a maximum p-value of 0.01 for the Benjamini-Hochberg adjustment method as our cut-off. Results: We observed the four previously reported pancreatic adenocarcinoma driver genes (KRAS, TP53, SMAD4, and CDKN2A) to be the genes most frequently mutated in White (n = 132) and Asian (n = 9) PDAC samples. In Black (n = 5) samples, PDAC appears to be only partially driven by mutation of these driver genes. We found Black PDAC samples have a distinct mutational landscape and harbor somatic mutations in additional genes, including: CSMD2 (42.9%), RYR1 (28.6%), CBLL2 (28.6%), ANKRD24 (28.6%), SAMD7 (28.6%). The DNA methylation landscape of PDAC patients is also distinct with respect to sociocultural race, with the majority of differentially-methylated loci present to a greater degree in Black (53.8%) or Asian samples (28.2%), compared to White (17.9%) samples. Gene expression data also follow this trend, with the majority of genes showing the highest degree of differential expression in Black (82.4%) versus Asian (14.7%) or White (2.9%) patients. Conclusion: Our preliminary analyses suggest racial heterogeneity exists at the level of DNA methylation, gene expression and somatic mutation. We discovered that reporting on PDAC driver mutations is likely biased by the overrepresentation of White patient samples in the TCGA dataset – the largest publicly available dataset with data on sociocultural race. Given our preliminary results, further work to describe the DNA methylation and gene expression landscape in PDAC with respect to sociocultural race is imperative. However, until minority representation is improved in such biobanking efforts – the ability to perform molecular profiling of PDAC within those populations experiencing disparate incidence and outcomes remains underpowered. Citation Format: Haleigh Tianna Larson, Ankit Chhoda, Astrid Hengartner, Nesrin Hasan, Nensi Ruzgar, Sri Yalamanchi, John W. Kunstman, James J. Farrell, Anup Sharma, Nita Ahuja. Racial heterogeneity in the molecular landscape of pancreatic adenocarcinoma: A call for action [abstract]. In: Proceedings of the AACR Virtual Conference: 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2021 Oct 6-8. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PO-155.

Keeping up with venetoclax for leukemic malignancies: key findings, optimal regimens and clinical considerations

Introduction Venetoclax has transformed the treatment landscape in hematologic malignancies, especially in elderly population. With high rates of remission, deep and durable responses, and safe toxicity profile, venetoclax in combination therapy has been extremely effective, garnering accelerated approval and becoming standard of care in lymphoid and myeloid malignancies. Areas covered The role of venetoclax in the intrinsic apoptotic pathway is covered. This includes preclinical and clinical experience of venetoclax monotherapy and combination therapy in relapsed/refractory and frontline CLL, AML, ALL and high-risk MDS, with an emphasis on key clinical trials and efficacy of combination regimens in distinct mutational landscapes. Strategies to mitigate myelosuppression, manage dose adjustments and infectious complications are addressed. Expert opinion Targeting BCL-2 offers a safe and highly effective adjunct to available therapies in hematologic malignancies. Despite success and frequent utilization of venetoclax, several resistance mechanisms have been elucidated, prompting development of novel combinatorial strategies. Further, on-target myelosuppression of venetoclax is a key obstacle in clinical practice, requiring diligent monitoring and practice-based knowledge of dose modifications. Despite these limitations, venetoclax has gained tremendous popularity in hematologic-oncology, becoming an integral component of numerous combination regimes, with ongoing plethora of clinical trials encompassing standard chemotherapy, targeted agents and immune-based approaches.

Genomic Sub-Classification of Ovarian Clear Cell Carcinoma Revealed by Distinct Mutational Signatures.

Simple SummaryIt is well-known that ovarian clear cell carcinoma presents unique molecular traits in comparison to other ovarian cancer subtypes, partially reflecting on chemotherapy resistance. Here, by investigating a panel of cancer-associated genes in a Danish population, our data showed that patients were further stratified into four different molecular subgroups: “PIK3CA”, “ARID1A”, “PIK3CA-ARID1A” and “Undetermined”, in regard to the presence of mutation on these genes. Somatic signature investigation further revealed that those subgroups share common features, such as ageing and defective MMR, whilst also bearing unique signatures. These findings suggest that different groups possess specific molecular backgrounds, indicating that such individuals could better benefit from more individualized therapy regimens.Ovarian clear cell carcinoma (OCCC) is characterized by dismal prognosis, partially due to its low sensitivity to standard chemotherapy regimen. It is also well-known for presenting unique molecular features in comparison to other epithelial ovarian cancer subtypes. Here, we aim to identify potential subgroups of patients in order to (1) determine their molecular features and (2) characterize their mutational signature. Furthermore, we sought to perform the investigation based on a potentially clinically relevant setting. To that end, we assessed the mutational profile and genomic instability of 55 patients extracted from the Gynecologic Cancer Database (DGCD) by using a panel comprised of 409 cancer-associated genes and a microsatellite assay, respectively; both are currently used in our routine environment. In accordance with previous findings, ARID1A and PIK3CA were the most prevalent mutations, present in 49.1% and 41.8%, respectively. From those, the co-occurrence of ARID1A and PIK3CA mutations was observed in 36.1% of subjects, indicating that this association might be a common feature of OCCC. The microsatellite instability frequency was low across samples. An unbiased assessment of signatures identified the presence of three subgroups, where “PIK3CA” and “Double hit” (with ARID1A and PIK3CA double mutation) subgroups exhibited unique signatures, whilst “ARID1A” and “Undetermined” (no mutations on ARID1A nor PIK3CA) subgroups showed similar profiles. Those differences were further indicated by COSMIC signatures. Taken together, the current findings suggest that OCCC presents distinct mutational landscapes within its group, which may indicate different therapeutic approaches according to its subgroup. Although encouraging, it is noteworthy that the current results are limited by sample size, and further investigation on a larger group would be crucial to better elucidate them.

Genomic analyses of high-grade neuroendocrine gynecological malignancies reveal a unique mutational landscape and therapeutic vulnerabilities.

High‐grade neuroendocrine carcinoma of gynecologic origin (NEC‐GYN) is a highly aggressive cancer that often affects young women. The clinical management of NEC‐GYN is typically extrapolated from its counterpart, small cell carcinoma of the lung (SCLC), but, unfortunately, available therapies have limited benefit. In our NEC‐GYN cohort, median progression‐free survival (PFS) and overall survival (OS) were 1 and 12 months, respectively, indicating the highly lethal nature of this cancer. Our comprehensive genomic analyses unveiled that NEC‐GYN harbors a higher mutational burden with distinct mutational landscapes from SCLC. We identified 14 cancer driver genes, including the most frequently altered KMT2C (100%), KNL1 (100%), NCOR2 (100%), and CCDC6 (93%) genes. Transcriptomic analysis identified several novel gene fusions; astonishingly, the MALAT1 lincRNA gene was found in ˜ 20% of all fusion events in NEC‐GYN. Furthermore, NEC‐GYN exhibited a highly immunosuppressive state, intact RB1 expression, and was uniquely enriched with the YAP1 high molecular subtype. Our study identifies several potential therapeutic targets and suggests an urgent need to re‐evaluate the treatment options for NEC‐GYN.