Genomic Intratumor Heterogeneity Research Articles

Abstract PO1-07-11: Radiogenomic-based imaging intratumor heterogeneity model predicts breast cancer prognosis and unveils therapeutic targets

Abstract Background: Intratumor heterogeneity (ITH) refers to variations observed among cancer cells within a single tumor, posing significant challenges in clinical practice due to its contribution to treatment resistance and unfavorable outcome. However, the inconvenience of multi-region biopsy and limitations of genomic sequencing based on limited tissue impede the practical detection of ITH. Consequently, there is an urgent need for a non-invasive method that comprehensively captures ITH from a holistic perspective of the entire tumor. Methods: We utilized a large multicenter dataset comprising dynamic contrast-enhanced magnetic resonance images from breast cancer patients (n = 1423) along with matched multiomics data (n = 468) to develop a non-invasive machine learning approach for measuring ITH. We extracted quantitative radiomic features from both the entire tumor and peritumor regions, with a specific focus on features associated with imaging heterogeneity. Using these radiomic features, we established an imaging ITH (IITH) model. The robustness of IITH evaluation was determined by assessing its correlation with genomic ITH (employing the mutant-allele tumor heterogeneity [MATH] algorithm) and pathological cellular ITH (analyzing variation in quantitative nuclear features extracted through digital pathology). Prognostic power was evaluated using Kaplan-Meier and multivariate Cox proportional hazards analyses. Integrated multiomics analyses were performed to investigate the molecular basis of different IITH subgroups. Results: We developed a non-invasive radiomic signature to quantify imaging ITH (IITH) in the FUSCC cohort. Breast cancer patients were retrospectively categorized into high and low IITH groups. Multivariate Cox analysis identified high IITH as an independent predictor of poor prognosis in breast cancer patients, even after adjusting for clinical risk factors such as tumor size, positive lymph nodes, clinical subtype and lymphovascular invasion status. These findings were further validated in the DUKE cohort, confirming the prognostic value of IITH. Moreover, we substantiated the robustness of IITH by demonstrating its association with genomic and pathological ITH. Multiomics analysis revealed the activation of oncogenic pathways and metabolic dysregulation in high-IITH tumors. Intriguingly, our investigation also highlighted ferroptosis as a vulnerability and potential therapeutic target in high-IITH tumors, which was further supported by evidence from the TCGA cohort. Conclusion: Radiomic-based assessment of ITH provides a non-invasive approach to comprehensively capture ITH and predict the prognosis of breast cancer patients. Targeting ferroptosis may hold promise as a treatment strategy for patients with high IITH. Citation Format: Guan-Hua Su, Yi Xiao, Chao You, Ren-Cheng Zheng, Shen Zhao, He Wang, Yi-Zhou Jiang, Ya-Jia Gu, Zhi-Ming Shao. Radiogenomic-based imaging intratumor heterogeneity model predicts breast cancer prognosis and unveils therapeutic targets [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 PO1-07-11.

Abstract PO3-15-10: Enhanced Cancer Cell Proliferation and Aggressive Phenotype Counterbalance in Breast Cancer with High BRCA1 Gene Expression

Abstract Introduction: It is estimated that 5–10% of all breast cancer cases have a hereditary component with BRCA1 mutation being one of the most frequently observed gene mutations in breast cancer patients. BRCA1 plays a crucial role in DNA repair, and its mutation has been extensively studied. However, the clinical significance of BRCA1 gene expression remains largely unexplored. Given that heightened DNA repair mechanisms can potentially increase cancer cell proliferation, we hypothesized that breast cancer with high BRCA1 gene expression might be associated with aggressive tumor biology and worse survival. Methods: The clinical, pathological and gene expression levels of a total of 6,245 breast cancer patients were analyzed from three large independent cohorts: METABRIC (n = 1,903), GSE96058 (n = 3,273), and The Cancer Genome Atlas (TCGA, n = 1,069). The data was retrieved through cBioPortal. The xCell algorithm was used to correlate the BRCA1 gene expression with the stromal and immune cell fractions infiltrating the tumor microenvironment (TME). Results: BRCA1 gene expression was higher in breast cancer patients without BRCA1 mutation, and it correlated with the DNA repair activity (p = 0.026 and p < 0.01 respectively), however, it did not correlate with BRCA2 gene expression (p = 0.38). Breast cancer with high BRCA1 gene expression was associated with cancer cell proliferation as evidenced by higher Nottingham histological grade (p < 0.001), Ki67 expression (p < 0.001), significant enrichment of cell proliferation-related gene sets such as E2F Targets, G2M Checkpoint, MYC Targets V1 and V2, Mitotic Spindle (all FDR < 0.25), and significantly less infiltration of stromal cells such as adipocytes, fibroblasts, microvascular and lymphatic endothelial cells, and pericytes (all p < 0.05). High BRCA1 gene expression was associated with higher homologous recombination deficiency, intratumor genomic heterogeneity, and fraction altered (all p < 0.001); however, there was no correlation observed with mutation rates or neoantigens. It was observed that breast cancer with high BRCA1 gene expression had less infiltration of CD8 T cells, dendritic cells, regulatory T cells, and B cells and had higher infiltration of Th1 cells (all p < 0.05). To our surprise, there was no significant difference in overall survival regardless of the subtypes (except for ER+/HER2- subtype in METABRIC cohort, p = 0.03). Breast cancer with low BRCA1 gene expression enriched cancer aggravating pathway gene sets such as Cancer Stem Cell-related signaling pathways (NOTCH and HEDGEHOG), Angiogenesis, Epithelial Mesenchymal Transition, Inflammatory Response, and TGF-beta signaling (all FDR < 0.25). Conclusion: Contrary to our initial hypothesis, we did not find any significant association between BRCA1 gene expression and survival outcomes in breast cancer patients. Based on the results of our study, we speculate that the interplay between enhanced cancer cell proliferation and aggressive tumor characteristics may counterbalance the effect of high BRCA1 expression in breast cancer. Citation Format: Kohei Chida, Masanori Oshi, Arya Mariam Roy, Itaru Endo, Kazuaki Takabe. Enhanced Cancer Cell Proliferation and Aggressive Phenotype Counterbalance in Breast Cancer with High BRCA1 Gene Expression [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 PO3-15-10.

Transcriptomic and genomic profiling of multiple primary colorectal cancers reveals intratumor heterogeneity and a distinct immune microenvironment

This study reported on the intratumor genomic and immunological heterogeneity of different tumor lesions from a single patient with multiple primary colorectal cancer (MPCC). The goal of this study was to explore the molecular and microenvironment characteristics of tumor lesions from different primary sites in a patient with MPCC.A total of three tumor lesions located in the hepatic flexure of the transverse colon, sigmoid colon, and rectum were collected from a 72-year-old male patient with MPCC. All three tumor samples were examined by using whole-exome sequencing (WES) and single-cell RNA sequencing (scRNA-seq). The transcriptome data of The Cancer Genome Atlas (TCGA) colon cancer (COAD) dataset were explored to characterize the biological impacts of certain immune cells. Only three nonsynonymous mutations were shared by all of the tumor lesions, whereas a number of single nucleotide variant (SNV) and copy number variation (CNV) mutations were shared by tumor samples from the sigmoid colon and rectum. Transcriptomic analysis showed that tumor lesions derived from the transverse colon had decreased levels of RTK, ERK, and AKT pathway activity, thus suggesting lower oncogenic properties in the transverse lesion compared to the other two samples. Further immune landscape evaluation by using single-cell transcriptomic analysis displayed significant intratumor heterogeneity in MPCC. Specifically, more abundant mucosal-associated invariant T (MAIT) cell infiltration was found in transverse colon tumor lesions. Afterwards, we found that higher MAIT cell infiltration may correlate with a better prognosis of patients with colon cancer (immunohistochemical status was MSI-L/pMMR) by using a publicly available TCGA dataset.

Association of a high E2F targets score with survival in hepatocellular carcinoma patients.

4106 Background: Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related mortality. Multiple staging systems have all been proposed to date; however, the optimal tool for stratification of prognosis is still not universally accepted. E2F targets are the essential component of cell proliferation, thus we hypothesized that a score to quantify E2F activity is expected to reflect the aggressiveness and prognosis of HCC. Methods: Total of 655 HCC patients from TCGA (The Cancer Genome Atlas) -HCC ( n=358), GSE6764 ( n=75), GSE76427 ( n = 115), and GSE89377 ( n=107) cohorts were analyzed. The score was generated using MSigDb Hallmark E2F Targets gene set using Gene Set Variation Analysis. Results: The E2F targets scores of TGCA-HCC patients showed a bimodal distribution, thus high vs. low score groups were divided by median. As expected, high E2F targets enriched all of the Hallmark cell proliferation-related gene sets; E2F targets, G2M checkpoint, MYC targets v1 and v2, and Mitotic spindle. It also enriched gene sets known to aggravate cancer, such as Glycolysis, mTORC1 signaling, DNA repair, and Unfolded protein response. E2F targets were significantly associated with histological grade, tumor size, and stage, as well as proliferation score and MKI67 expression. Furthermore, a higher E2F targets score was significantly associated with higher intra-tumoral genomic heterogeneity and homologous recombination deficiency, suggesting greater tumor aggressiveness. In agreement, E2F targets score correlated with the pathological progression from normal liver, cirrhosis, dysplasia, to early and advanced HCC consistently in two cohorts (GSE6764 and GSE89377). Further, the abundance of hepatocytes, fibroblasts, adipocytes, and lymphatic endothelial cells were all significantly less in high E2F HCC, which reflects proliferative cancer. On the other hand, there was no relationship between E2F and mutation rates or neoantigens. High E2F was associated with high infiltration of anti-cancerous immune cells; CD8, CD4 memory, and Th1 cells, however, there was no difference in cytolytic activity, and it did not enrich any of immune response-related gene sets. High E2F HCC was associated with worse disease-free (DFS), disease-specific (DSS), and overall survival (OS), and this was the case in both early (I and II) and late (III and IV) stages. A multivariate analysis revealed that the E2F targets score was an independent prognostic factor for OS (HR=1.68, 95%CI= 1.15–2.46, p = 0.007) as well as DSS (HR=1.81, 95%CI=1.27–2.59, p = 0.001) in patients with HCC. Conclusions: We found that the E2F targets score not only indicates cell proliferation, but also is associated with cancer aggressiveness and worse survival. Our findings suggest a possible future use of the E2F targets score as a prognostic biomarker in patients with HCC.

E2F target score is associated with cell proliferation and survival of patients with hepatocellular carcinoma

BackgroundE2F target genes are essential for the cell cycle. A score that quantifies its activity is expected to reflect the aggressiveness and prognosis of hepatocellular carcinoma. MethodsCohorts of hepatocellular carcinoma patients (total n = 655) from The Cancer Genome Atlas, GSE89377, GSE76427, and GSE6764 were analyzed. The cohorts were divided into high versus low by the median. ResultsAll the Hallmark cell proliferation-related gene sets were consistently enriched in hepatocellular carcinoma with high E2F targets score, and E2F score was associated with grade, tumor size, American Joint Committee on Cancer staging, proliferation score, and MKI67 expression, as well as with less abundance of hepatocytes and stromal cells. E2F targets enriched DNA repair, mTORC1 signaling, glycolysis, and unfolded protein response gene sets and were significantly associated with the higher intratumoral genomic heterogeneity, homologous recombination deficiency, and progression of hepatocellular carcinoma. On the other hand, there was no relationship between E2F targets and mutation rates or neoantigens. High E2F hepatocellular carcinoma did not enrich any of the immune-response–related gene sets but was associated with high infiltration of Th1, Th2 cells, and M2 macrophage; however, there was no difference in cytolytic activity. In both early (I and II) and late (III and IV) stages of hepatocellular carcinoma, a high E2F score was associated with worse survival and was an independent prognostic factor for overall and disease-specific survival in patients with hepatocellular carcinoma. ConclusionThe E2F target score, associated with cancer aggressiveness and worse survival, could be used as a prognostic biomarker in patients with hepatocellular carcinoma.

Analysis of genomic and immune intratumor heterogeneity in linitis plastica via multiregional exome and T-cell receptor sequencing.

The molecular landscape and the intratumor heterogeneity (ITH) architecture of gastric linitis plastica (LP) are poorly understood. We performed whole-exome sequencing (WES) and T-cell receptor (TCR) sequencing on 40 tumor regions from four LP patients. The landscape and ITH at the genomic and immunological levels in LP tumors were compared with multiple cancers that have previously been reported. The lymphocyte infiltration was further assessed by immunohistochemistry (IHC) in LP tumors. In total, we identified 6339 non-silent mutations from multi-samples, with a median tumor mutation burden (TMB) of 3.30 mutations per Mb, comparable to gastric adenocarcinoma from the Cancer Genome Atlas (TCGA) cohort (P = 0.53). An extremely high level of genomic ITH was observed, with only 12.42%, 5.37%, 5.35%, and 30.67% of mutations detectable across 10 regions within the same tumors of each patient, respectively. TCR sequencing revealed that TCR clonality was substantially lower in LP than in multi-cancers. IHC using antibodies against CD4, CD8, and PD-L1 demonstrated scant T-cell infiltration in the four LP tumors. Furthermore, profound TCR ITH was observed in all LP tumors, with no T-cell clones shared across tumor regions in any of the patients, while over 94% of T-cell clones were restricted to individual tumor regions. The Morisita overlap index (MOI) ranged from 0.21 to 0.66 among multi-regions within the same tumors, significantly lower than that of lung cancer (P = 0.002). Our results show that LP harbored extremely high genomic and TCR ITH and suppressed T-cell infiltration, suggesting a potential contribution to the frequent recurrence and poor therapeutic response of this adenocarcinoma.

Analysis of Immune Intratumor Heterogeneity Highlights Immunoregulatory and Coinhibitory Lymphocytes as Hallmarks of Recurrence in Stage I Non–Small Cell Lung Cancer

Our understanding of the molecular mechanisms underlying postsurgical recurrence of non–small cell lung cancer (NSCLC) is rudimentary. Molecular and T cell repertoire intratumor heterogeneity (ITH) have been reported to be associated with postsurgical relapse; however, how ITH at the cellular level impacts survival is largely unknown. Here we report the analysis of 2880 multispectral images representing 14.2% to 27% of tumor areas from 33 patients with stage I NSCLC, including 17 cases (relapsed within 3 years after surgery) and 16 controls (without recurrence ≥5 years after surgery) using multiplex immunofluorescence. Spatial analysis was conducted to quantify the minimum distance between different cell types and immune cell infiltration around malignant cells. Immune ITH was defined as the variance of immune cells from 3 intratumor regions. We found that tumors from patients having relapsed display different immune biology compared with nonrecurrent tumors, with a higher percentage of tumor cells and macrophages expressing PD-L1 (P =.031 and P =.024, respectively), along with an increase in regulatory T cells (Treg) (P =.018), antigen-experienced T cells (P =.025), and effector-memory T cells (P =.041). Spatial analysis revealed that a higher level of infiltration of PD-L1+ macrophages (CD68+PD-L1+) or antigen-experienced cytotoxic T cells (CD3+CD8+PD-1+) in the tumor was associated with poor overall survival (P =.021 and P =.006, respectively). A higher degree of Treg ITH was associated with inferior recurrence-free survival regardless of tumor mutational burden (P =.022), neoantigen burden (P =.021), genomic ITH (P =.012) and T cell repertoire ITH (P =.001). Using multiregion multiplex immunofluorescence, we characterized ITH at the immune cell level along with whole exome and T cell repertoire sequencing from the same tumor regions. This approach highlights the role of immunoregulatory and coinhibitory signals as well as their spatial distribution and ITH that define the hallmarks of tumor relapse of stage I NSCLC.

The Role of Quiescence in Acute Myeloid Leukemia Growth

Acute myeloid leukemia (AML) is the most common leukemia in adults and its prognosis is usually poor. Despite the introduction of targeted treatments in recent years, AML remains a high-mortality disease with a 5-year survival of less than 30%. Emerging evidence suggest that therapy failure and leukemia relapse are due to the intra-tumoral genomic and biological heterogeneity. At biological level, AML is hierarchically organized with leukemia stem cells (LSCs) at the apex. LSCs are a rare cell sub-population with self-renewal capacity, responsible for leukemia initiation and maintenance. Standard AML therapies have limited effects on LSCs, mainly due to their property of exiting the cell cycle and enter quiescence. Preliminary data obtained in our group have shown that different leukemia-initiating oncogenes (NPMc+, PML-RARα and MLL-AF9) share the property of enforcing quiescence in pre-leukemic hematopoietic stem cells (HSCs), and that this is critical for the progression and maintenance of the leukemia clone. Underlying molecular mechanisms, however, are unknown. To this end, we have performed an in vivo reverse genetic screening to identify quiescence-related genes indispensable for leukemia growth. Among the identified hits, Socs2, Stat1 and Sytl4 silencing prevented AML outgrowth in vivo. Notably, Socs2 and Stat1 interference increased proliferation, prevented accumulation of quiescent blasts and induced apoptosis. Interestingly, Socs2 and Stat1 silencing exerted no effects on in vitro proliferation, cell cycle distribution or survival of AML blasts, suggesting that their effects are largely dependent on the in vivo leukemia context. Single-cell RNAseq (scRNAseq) analysis of Socs2-interfered blasts showed marked down-regulation of genes characterizing the dormant status of quiescent HSCs, suggesting that loss of quiescence in Socs2-interfered blasts is linked to the loss of their regenerative potential. Since dormancy and self-renewal potential in HSCs are antagonized by prolonged stress signals, we analyzed scRNAseq data for activation of the integrated stress response (ISR). Strikingly, Socs2-interfered cells showed aberrant activation of ATF4, UPR and autophagic transcriptional programs, which was evident in both proliferating and cell cycle restricted blasts, at variance with control blasts that showed increased ISR expression specifically in proliferating cells. Since elevated levels of UPR may act as danger signals and favor immune-mediated clearance in vivo, we analyzed immune-related signaling pathways. Consistently, Socs2-silenced blasts showed a dramatic down-regulation of specific immune check-point molecules, including CD24a, galectin 9 and VISTA, which are involved in the regulation of B cells, T cells, NK cells and macrophages. Based on these findings, we hypothesized that Socs2 regulates the resolution of stressful signals that eventually accumulate in hyper-proliferating AML blasts by allowing cells to enter quiescence and activate pathways of ISR resolution, including upregulation of immune check-point molecules. If blasts fail to enter quiescence, as in in the absence of Socs2 expression, cells maintain sustained ISR activation and downregulate immune check-point molecules, thus triggering immune-mediated cell death. Consistently, the anti-leukemic effect of Socs2-silencing was partially rescued upon propagation into immunocompromised mice. As well, macrophage depletion prolonged disease latency of Socs2-interfered blasts in immunocompetent mice. These findings provide preliminary evidence of the existence, in AML blasts, of an adaptive response to hyperproliferation that involves ISR activation, induction of quiescence and immune evasion. Targeting this adaptive response, as by Socs2 interference, may activate potent mechanisms of AML immune clearance.

FOXA1 repression drives lineage plasticity and immune heterogeneity in bladder cancers with squamous differentiation

Cancers arising from the bladder urothelium often exhibit lineage plasticity with regions of urothelial carcinoma adjacent to or admixed with regions of divergent histomorphology, most commonly squamous differentiation. To define the biologic basis for and clinical significance of this morphologic heterogeneity, here we perform integrated genomic analyses of mixed histology bladder cancers with separable regions of urothelial and squamous differentiation. We find that squamous differentiation is a marker of intratumoral genomic and immunologic heterogeneity in patients with bladder cancer and a biomarker of intrinsic immunotherapy resistance. Phylogenetic analysis confirms that in all cases the urothelial and squamous regions are derived from a common shared precursor. Despite the presence of marked genomic heterogeneity between co-existent urothelial and squamous differentiated regions, no recurrent genomic alteration exclusive to the urothelial or squamous morphologies is identified. Rather, lineage plasticity in bladder cancers with squamous differentiation is associated with loss of expression of FOXA1, GATA3, and PPARG, transcription factors critical for maintenance of urothelial cell identity. Of clinical significance, lineage plasticity and PD-L1 expression is coordinately dysregulated via FOXA1, with patients exhibiting morphologic heterogeneity pre-treatment significantly less likely to respond to immune checkpoint inhibitors.

The clonal expression genes associated with poor prognosis of liver cancer.

The extensive spatial genomic intratumor heterogeneity (ITH) in liver cancer hindered treatment development and limited biomarker design. Early events that drive tumor malignant transformation in tumor founder cells are clonally present in all tumor cell populations, which provide stable biomarkers for the localization of tumor cells and patients’ prognosis. In the present study, we identified the recurrently clonal somatic mutations and copy number alterations (CNAs) (893 clonal somatic mutations and 6,617 clonal CNAs) in 353 liver cancer patients from The Cancer Genome Atlas (TCGA) and evaluated their prognosis potential. We showed that prognosis-related clonal alterations might play essential roles in tumor evolution. We identified 32 prognosis related clonal alterations differentially expressed between paired normal and tumor samples, that their expression was cross-validated by three independent cohorts (50 paired samples in TCGA, 149 paired samples in GSE76297, and 9 paired samples in SUB6779164). These clonal expression alterations were also significantly correlated with clinical phenotypes. Using stepwise regression, we identified five (UCK2, EFNA4, KPAN2, UBE2T, and KIF14) and six (MCM10, UCK2, IQGAP3, EFNA4, UBE2T, and KPNA2) clonal expression alterations for recurrence and survival model construction, respectively. Furthermore, in 10 random repetitions, we showed strong applicability of the multivariate Cox regression models constructed based on the clonal expression genes, which significantly predicted the outcomes of the patients in all the training and validation sets. Taken together, our work may provide a new avenue to overcome spatial ITH and refine biomarker design across cancer types.

Genomic landscapes of canine splenic angiosarcoma (hemangiosarcoma) contain extensive heterogeneity within and between patients.

Cancer genomic heterogeneity presents significant challenges for understanding oncogenic processes and for cancer’s clinical management. Variation in driver mutation frequency between patients with the same tumor type as well as within an individual patients’ cancer can shape the use of mutations as diagnostic, prognostic, and predictive biomarkers. We have characterized genomic heterogeneity between and within canine splenic hemangiosarcoma (HSA), a common naturally occurring cancer in pet dogs that is similar to human angiosarcoma (AS). HSA is a clinically, physiologically, and genomically complex canine cancer that may serve as a valuable model for understanding the origin and clinical impact of cancer heterogeneity. We conducted a prospective collection of 52 splenic masses from 43 dogs (27 HSA, 15 benign masses, and 1 stromal sarcoma) presenting for emergency care with hemoperitoneum secondary to a ruptured splenic mass. Multi-platform genomic analysis included matched tumor/normal targeted sequencing panel and exome sequencing. We found candidate somatic cancer driver mutations in 14/27 (52%) HSAs. Among recurrent candidate driver mutations, TP53 was most commonly mutated (30%) followed by PIK3CA (15%), AKT1 (11%), and CDKN2AIP (11%). We also identified significant intratumoral genomic heterogeneity, consistent with a branched evolution model, through multi-region exome sequencing of three distinct tumor regions from selected primary splenic tumors. These data provide new perspectives on the genomic landscape of this veterinary cancer and suggest a cross-species value for using HSA in pet dogs as a naturally occurring model of intratumoral heterogeneity.

Abstract 760: Concordance of DNA copy number profiles between primary and metastatic colorectal carcinoma

Abstract The most common form of genomic instability in sporadic colorectal cancer (CRC) is chromosomal instability, a phenotype characterized by a high frequency of DNA copy number gain (CNG) and loss (CNL). Given the fundamental role of chromosomal instability in the pathogenesis of CRC, this study aimed to investigate the concordance of DNA copy number variants (CNV) between primary and metastatic CRC to better understand how the genomic structure differs during tumor evolution. In this study, the SurePrint G3 Human Genome CGH+SNP 2x400K Microarray (Agilent, SC, California, USA) was used for genome-wide screening of CNV in 9 pairs of primary tumors and metachronous liver metastases obtained during surgical resection from patients diagnosed with advanced CRC. Data from the Microarray-based Comparative Genomic Hybridization was analyzed by COSMIC Cancer Gene Census (CGC) and an independent non-CGC panel to map hotspot regions harboring genes causally implicated in cancer in the course of the metastatic cascade. Also, unique CNV in metastases were further investigated to identify loci advantageous for tumor progression and those presumably associated with therapy resistance. Overall, CNG observed in primary tumors were highly concordant with those in liver metastases. The CNG hotspot regions for both tissues represented chr7 (p22.3-p13), chr8 (q21.13-q24.3), chr13 (q12.11-q13.3), chr20 (q11.1-q13.33) and chrX (q11.1-q28) loci, while the most frequent CNL was at chr8 (p21.3-p12) locus. All identified loci underwent CNV events with a higher frequency in metastases (67-100%) than in primary tumors (55%). The identified genomic loci with CNG encode DNA repair genes (such as PMS2, NBN, BRCA2, RAD54B, RAD21, RPA3,4, and TREX2), homeobox genes (HOXA9,11,13), genes encoding centrosome-associated proteins (CETN2, MPLKIP), proto-oncogenes (MYC), and also tumor suppressor (ATRX, ASXL1). Additionally, an analysis of unique CNV within distinct tissues revealed CNG at Chr6 (p25.1-p22.3) in 89% of metastatic samples and absent in all the primary tumor lesions. This particular genomic region contains proto-oncogene DEK. Although the analysis is still underway, we have identified several shared and unique regions of altered copy number in both, primary tumors and metastases. We conclude that despite the high inter- and intra-tumoral genomic heterogeneity, metachronous metastases “inherit” a similar profile of DNA CNV from their respective primary tumor tissues. We intend to further extend our studied group of patients and perform integrative analyses of CNV with gene expression. This study was supported by the Charles University (UNCE/MED/006) and the Grant Agency of the Czech Republic (21-04607X, 21-27902S) Citation Format: Michal Kroupa, Kristyna Tomasova, Katerina Saskova, Jana Drabova, Josef Horak, Ludmila Vodickova, Jachym Rosendorf, Vaclav Liska, Pavel Vodicka. Concordance of DNA copy number profiles between primary and metastatic colorectal carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 760.

Abstract 1603: Genomic transcriptomic evolution in TRACERx lung cancer and metastasis

Abstract Background: Genomic intra-tumor heterogeneity (ITH) drives tumor evolution, leading to immune evasion and resistance to therapy. Emerging evidence implicates the transcriptome as a source of important variation that impacts tumor phenotype. Here, we perform a genomic-transcriptomic analysis of intra-tumor transcriptomic diversity upon 941 tumor regions taken from 357 TRACERx non-small cell lung cancers (NSCLC) across primary and metastatic disease subjected to high-depth bulk DNA and RNA sequencing, as well as 91 tumor-adjacent normal tissue samples. Results: Genomic and transcriptomic diversity are linked across primary and metastatic disease, with expression signatures of proliferation being enriched in the metastasis seeding subclone of the primary tumor relative to non-metastasis seeding subclones. Copy-number independent allele-specific expression (CN-independent ASE), a source of transcriptome-specific diversity, affects 1% (± 0.5%) of genes and is underpinned by aberrant allele-specific methylation (OR=7.58, p≤2.2x10-16), thus providing a window to the NSCLC epigenomic landscape. Driver mutations in chromatin remodellers and histone modifiers, in particular SETD2 and KDM5C, are associated with increased global levels of CN-independent ASE (p=0.0001). In genomically stable tumors, high levels of CN-independent ASE are linked to expression signatures consistent with genomic instability and proliferation (R=0.58, p=0.001), highlighting convergence between the genome and transcriptome in tumor evolution. For the first time, we uncover mutational signatures of RNA editing. Analysis of their activity links the expression of ADAR and APOBEC enzymes to editing processes revealing otherwise hidden APOBEC activity within tumors at sampling (RNA APOBEC activity identified in 188 tumor regions (32%) without evidence of DNA APOBEC activity). RNA editing activity is shared between primary tumors and paired metastasis, but not paired tumor-adjacent normal tissue, suggestive of heritability of this somatic transcriptional process. Finally, we combine multiple measures of genomic and transcriptomic variation in a multi-region approach to define important variation within cancer genes. We illustrate examples that would be missed with a purely genomic focus and demonstrate genomic-transcriptomic parallel evolution, converging on disruption to single cancer genes, such as FAT1 and APC, in different regions of a tumor. Conclusions: This work highlights the importance of the transcriptome during tumor evolution, as well as the power of integrative multi-omic assessments of ITH, and provides novel insight into the role of transcriptomic variation in lung cancer. Citation Format: James R. M. Black, Carlos Martinez-Ruiz, Clare Puttick, Jonas Demeulemeester, Elizabeth Larose Cadieux, Kerstin Thol, Thomas P. Jones, Selvaraju Veeriah, Cristina Naceur-Lombardelli, Andrew Rowan, Sophia Ward, Michelle Dietzen, Ariana Huebner, Maise Al Bakir, Miljana Tanic, Thomas B. Watkins, Emilia L. Lim, Ali M. Al Rashed, Daniel E. Cook, Rachel Rosenthal, Gareth Wilson, Alexander M. Frankell, Nnennaya Kanu, Kevin Litchfield, Nicolai J. Birkbak, Allan Hackshaw, Stephan Beck, Peter Van Loo, Mariam Jamal-Hanjani, the lung TRACERx Consortium, Charles Swanton, Nicholas McGranahan. Genomic transcriptomic evolution in TRACERx lung cancer and metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1603.

Copy-number intratumor heterogeneity increases the risk of relapse in chemotherapy-naive stage II colon cancer.

Optimal selection of high-risk patients with stage II colon cancer is crucial to ensure clinical benefit of adjuvant chemotherapy. Here, we investigated the prognostic value of genomic intratumor heterogeneity and aneuploidy for disease recurrence. We combined targeted sequencing, SNP arrays, fluorescence in situ hybridization, and immunohistochemistry on a retrospective cohort of 84 untreated stage II colon cancer patients. We assessed the clonality of copy-number alterations (CNAs) and mutations, CD8+ lymphocyte infiltration, and their association with time to recurrence. Prognostic factors were included in machine learning analysis to evaluate their ability to predict individual relapse risk. Tumors from recurrent patients displayed a greater proportion of CNAs compared with non-recurrent (mean 31.3% versus 23%, respectively; p = 0.014). Furthermore, patients with elevated tumor CNA load exhibited a higher risk of recurrence compared with those with low levels [p = 0.038; hazard ratio (HR) 2.46], which was confirmed in an independent cohort (p = 0.004; HR 3.82). Candidate chromosome-specific aberrations frequently observed in recurrent cases included gain of the chromosome arm 13q (p = 0.02; HR 2.67) and loss of heterozygosity at 17q22-q24.3 (p = 0.05; HR 2.69). CNA load positively correlated with intratumor heterogeneity (R = 0.52; p < 0.0001). Consistently, incremental subclonal CNAs were associated with an elevated risk of relapse (p = 0.028; HR 2.20), which we did not observe for subclonal single-nucleotide variants and small insertions and deletions. The clinico-genomic model rated an area under the curve of 0.83, achieving a 10% incremental gain compared with clinicopathological markers (p = 0.047). In conclusion, tumor aneuploidy and copy-number intratumor heterogeneity were predictive of poor outcome and improved discriminative performance in early-stage colon cancer. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

A Portrait of Intratumoral Genomic and Transcriptomic Heterogeneity at Single-Cell Level in Colorectal Cancer.

In the study of cancer, omics technologies are supporting the transition from traditional clinical approaches to precision medicine. Intra-tumoral heterogeneity (ITH) is detectable within a single tumor in which cancer cell subpopulations with different genome features coexist in a patient in different tumor areas or may evolve/differ over time. Colorectal carcinoma (CRC) is characterized by heterogeneous features involving genomic, epigenomic, and transcriptomic alterations. The study of ITH is a promising new frontier to lay the foundation towards successful CRC diagnosis and treatment. Genome and transcriptome sequencing together with editing technologies are revolutionizing biomedical research, representing the most promising tools for overcoming unmet clinical and research challenges. Rapid advances in both bulk and single-cell next-generation sequencing (NGS) are identifying primary and metastatic intratumoral genomic and transcriptional heterogeneity. They provide critical insight in the origin and spatiotemporal evolution of genomic clones responsible for early and late therapeutic resistance and relapse. Single-cell technologies can be used to define subpopulations within a known cell type by searching for differential gene expression within the cell population of interest and/or effectively isolating signal from rare cell populations that would not be detectable by other methods. Each single-cell sequencing analysis is driven by clustering of cells based on their differentially expressed genes. Genes that drive clustering can be used as unique markers for a specific cell population. In this review we analyzed, starting from published data, the possible achievement of a transition from clinical CRC research to precision medicine with an emphasis on new single-cell based techniques; at the same time, we focused on all approaches and issues related to this promising technology. This transition might enable noninvasive screening for early diagnosis, individualized prediction of therapeutic response, and discovery of additional novel drug targets.

Cold and heterogeneous T cell repertoire is associated with copy number aberrations and loss of immune genes in small-cell lung cancer

Small-cell lung cancer (SCLC) is speculated to harbor complex genomic intratumor heterogeneity (ITH) associated with high recurrence rate and suboptimal response to immunotherapy. Here, using multi-region whole exome/T cell receptor (TCR) sequencing as well as immunohistochemistry, we reveal a rather homogeneous mutational landscape but extremely cold and heterogeneous TCR repertoire in limited-stage SCLC tumors (LS-SCLCs). Compared to localized non-small cell lung cancers, LS-SCLCs have similar predicted neoantigen burden and genomic ITH, but significantly colder and more heterogeneous TCR repertoire associated with higher chromosomal copy number aberration (CNA) burden. Furthermore, copy number loss of IFN-γ pathway genes is frequently observed and positively correlates with CNA burden. Higher mutational burden, higher T cell infiltration and positive PD-L1 expression are associated with longer overall survival (OS), while higher CNA burden is associated with shorter OS in patients with LS-SCLC.

Genomic Heterogeneity of Pancreatic Ductal Adenocarcinoma and Its Clinical Impact.

Simple SummaryAlthough much progress has been made in recent years in the clinical management of solid tumors, pancreatic ductal adenocarcinoma (PDAC) remains a malignancy with limited therapeutical options. Indeed, responses to standard chemotherapy and targeted therapies vary widely when administered to unselected patient populations. This is in part due to the heterogeneous and variable molecular profile of PDAC. Here, we review current knowledge about the genomic heterogeneity of PDAC and its impact on disease behavior, and treatment including the molecular mechanisms of chemoresistance.Pancreatic ductal adenocarcinoma (PDAC) is one of the leading causes of cancer death due to limited advances in recent years in early diagnosis and personalized therapy capable of overcoming tumor resistance to chemotherapy. In the last decades, significant advances have been achieved in the identification of recurrent genetic and molecular alterations of PDAC including those involving the KRAS, CDKN2A, SMAD4, and TP53 driver genes. Despite these common genetic traits, PDAC are highly heterogeneous tumors at both the inter- and intra-tumoral genomic level, which might contribute to distinct tumor behavior and response to therapy, with variable patient outcomes. Despite this, genetic and genomic data on PDAC has had a limited impact on the clinical management of patients. Integration of genomic data for classification of PDAC into clinically defined entities—i.e., classical vs. squamous subtypes of PDAC—leading to different treatment approaches has the potential for significantly improving patient outcomes. In this review, we summarize current knowledge about the most relevant genomic subtypes of PDAC including the impact of distinct patterns of intra-tumoral genomic heterogeneity on the classification and clinical and therapeutic management of PDAC.

Abstract 2742: Integrated multiregional transcriptomic and multi-parameter single-cell imaging analysis of clear cell renal cell carcinoma elucidates diverse cellular communities present within the tumor microenvironment

Abstract Although genomic analyses of clear cell renal cell carcinoma (ccRCC) patients have revealed targetable pathways that have led to FDA-approved therapies, the responses to these therapies remain limited. The significant success of immune checkpoint inhibitors and anti-angiogenic agents suggest that ccRCC has a unique tumor microenvironment composition and tumor behavior that influences therapeutic response. Here, we describe an integrated proteogenomic method to study intratumoral heterogeneity (ITH), microenvironment composition, tumor spatial behavior, and cellular communities in ccRCC. A unique AI-based segmentation platform for multiplex immunofluorescence (MxIF) was developed to analyze an entire tissue slide at single-cell resolution, including 70 regions of interest per slide, providing significant information regarding spatial architecture. Primary ccRCC tumors collected from patients were biopsied at multiple locations and subjected to MxIF (20 markers, n = 10 sites, 4 pts, ~1,000,000 cells), RNA-seq (n = 8 sites, 3 pts) and CyTOF (n = 21 sites, 6 pts), allowing integrated multi-omics analysis at the single-cell level. Integrated analysis showed that genomic intratumor heterogeneity (ITH) was remarkably similar across all regions biopsied from the same patient, and the cellular populations present within each region of the same patient were alike. However, some cell types such as TCM CD4 T cells and Tem CD38 and Tem PD1+CD69+CD38- CD8 T cells, and CD163+PDL1+LAMP+ showed great inter-patient differences in the proportion of these cell populations. Notably, 14 CD4 T cell, 13 CD8 T cell, and 10 macrophage subpopulations were identified across the ccRCC tumors. Moreover, 14 microenvironment proximity communities based on MxIF imaging analysis of ~1 million cells were identified. The presence of B cell- and T cell-enriched communities (e.g., CD8 T cell enrichment and T-cell enrichment at the tumor border) correlated with the expression of interferon-gamma, PD1, IL-6, IL-10, PD-L1, CXCL13, and others. Macrophage-enriched communities correlated with the expression of CXCL12 and PDGFRB. Finally, tertiary lymphoid structures within the “B cell-enriched” communities correlating with the expression of CXCL13 were found in two tumors collected from one patient, with subsequent validation via H&amp;E staining. Further, B cell repertoire (BCR) analysis of RNA-seq of the tumors from this patient showed the presence of a large B cell clone in the tumors. In conclusion, via MxIF, 14 distinct spatial microenvironment communities with unique cytokine expression patterns were identified in ccRCC. Uncovering the spatial behavior of tumors can lead to the development of effective therapies personalized for each patient based on microenvironment composition and architecture. Citation Format: Natalia Miheecheva, Akshaya Ramachandran, Yang Lyu, Ekaterina Postovalova, Viktor Svekolkin, Ilia Galkin, Pavel Ovcharov, Diana Shamsutdinova, Vladimir Zyrin, Alexander Bagaev, Krystle Nomie, Felix Frenkel, Ravshan Ataullakhanov, James J. Hsieh. Integrated multiregional transcriptomic and multi-parameter single-cell imaging analysis of clear cell renal cell carcinoma elucidates diverse cellular communities present within the tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2742.

Precision Therapy for Mesothelioma: Feasibility and New Opportunities.

Simple SummaryMesothelioma remains a lethal cancer. Personalized treatment is lacking. Emerging insights into the genomic and epigenomic landscape of mesothelioma highlight promising opportunities for precision therapy, where are discussed.Malignant pleural mesotheliomas (MPMs) are characterised by their wide variation in natural history, ranging from minimally to highly aggressive, associated with both interpatient and intra-tumour genomic heterogeneity. Recent insights into the nature of this genetic variation, the identification of drivers, and the emergence of novel strategies capable of targeting vulnerabilities that result from the inactivation of key tumour suppressors suggest that new approaches to molecularly strategy therapy for mesothelioma may be feasible.

Phenotypic Heterogeneity and Metastasis of Breast Cancer Cells.

Although intratumoral genomic heterogeneity can impede cancer research and treatment, less is known about the effects of phenotypic heterogeneities. To investigate the role of cell migration heterogeneities in metastasis, we phenotypically sorted metastatic breast cancer cells into two subpopulations based on migration ability. Although migration is typically considered to be associated with metastasis, when injected orthotopically in vivo, the weakly migratory subpopulation metastasized significantly more than the highly migratory subpopulation. To investigate the mechanism behind this observation, both subpopulations were assessed at each stage of the metastatic cascade, including dissemination from the primary tumor, survival in the circulation, extravasation, and colonization. Although both subpopulations performed each step successfully, weakly migratory cells presented as circulating tumor cell (CTC) clusters in the circulation, suggesting clustering as one potential mechanism behind the increased metastasis of weakly migratory cells. RNA sequencing revealed weakly migratory subpopulations to be more epithelial and highly migratory subpopulations to be more mesenchymal. Depletion of E-cadherin expression from weakly migratory cells abrogated metastasis. Conversely, induction of E-cadherin expression in highly migratory cells increased metastasis. Clinical patient data and blood samples showed that CTC clustering and E-cadherin expression are both associated with worsened patient outcome. This study demonstrates that deconvolving phenotypic heterogeneities can reveal fundamental insights into metastatic progression. More specifically, these results indicate that migratory ability does not necessarily correlate with metastatic potential and that E-cadherin promotes metastasis in phenotypically sorted breast cancer cell subpopulations by enabling CTC clustering. SIGNIFICANCE: This study employs phenotypic cell sorting for migration to reveal a weakly migratory, highly metastatic breast cancer cell subpopulation regulated by E-cadherin, highlighting the dichotomy between cancer cell migration and metastasis.