71 Tumors with higher heterogeneity were associated with superior survival outcome amongst stage I lung cancer patients with low tumor mutational burden (TMB)

BackgroundTumor mutational burden (TMB) has been shown to predict response to immune checkpoint inhibitors.1 Furthermore, the FDA has approved the use of TMB as a biomarker for response to pembrolizumab in solid tumors.2 Simultaneously, the relationship between tumor heterogeneity and outcome has been studied across a range of cancer indications and has shown predictive value.3 For Lung Squamous Cell Carcinoma (LUSC) the utility of heterogeneity metrics has not been established. To study this relationship we used both TMB and tumor heterogeneity to stratify patients, compare outcomes, explore differences in immune cell enrichment, and predict driver genes.MethodsWe obtained Tumor Cancer Genome Atlas (TCGA) LUSC SNP, CNV, and RNASeq data from the GDC Data Portal4 and clinical data from the PanCancer Atlas dataset through cBioPortal.5 TMB was calculated by dividing the number of mutations by 38 to yield a mut/Mb value. To estimate tumor heterogeneity we ran PyClone, an algorithm that estimates the number of tumor clones.6 PyClone uses a random seed and output for the same sample may differ. We ran each sample in triplicate on three separate days yielding 9 runs per sample, yielding an average PyClone clone number. Clones with >2 mutations were counted. Using p-value minimization we chose 5 for the TMB cutoff and 4.6 for the PyClone cutoff. This yielded 4 groups: HTHP, HTLP, LTHP, and LTLP, where H - high, L- low, T-TMB, and P-Pyclone. Immune cell enrichment analysis was accomplished with ssGSEA via the GenePattern platform.7 Driver gene prediction was performed with OncoDriveClust8 via the R package maftools.9ResultsA statistically significant difference was found in progression free survival (PFS) between stage I LTHP (LTHPI, N = 15) and stage I LTLP (LTLPI, N = 77) patients (51.27 months vs. 25.4 months, p-value = 0.0059). Intriguingly, highly heterogeneous tumors revealed superior survival outcomes compared to less heterogeneous tumors in this subgroup. LTLPI patients were enriched for immature B cells, regulatory T cells, and myeloid derived suppressor cells (figure 1). Three driver genes were predicted for the LTLPI cohort (NFE2L2, PIK3CA, and TP53), while none were predicted for the LTHPI cohort.Abstract 71 Figure 1Immune Cell Gene Set EnrichmentConclusionsContrary to previous literature, superior survival outcomes were observed in high tumor heterogeneity, low TMB Stage I LUSC patients. Early stage patients can be stratified using heterogeneity metrics like PyClone. Given the presence of specific driver genes and an immunosuppressive tumor microenvironment, this population warrants further investigation for therapeutic implications.AcknowledgementsThis research was supported in part through the computational resources and staff contributions provided by the Genomics Compute Cluster which is jointly supported by the Feinberg School of Medicine, the Center for Genetic Medicine, and Feinberg’s Department of Biochemistry and Molecular Genetics, the Office of the Provost, the Office for Research, and Northwestern Information Technology. The Genomics Compute Cluster is part of Quest, Northwestern University’s high performance computing facility, with the purpose to advance research in genomics.Trial RegistrationN/AReferencesSamstein RM, Lee C-H, Shoushtari AN, Hellmann MD, Shen R, Janjigian YY, et al. Tumor mutational load predicts survival after immunotherapy across multiple cancer types. Nature Genetics 2019;51(2):202–6.Center for Drug Evaluation and Research. FDA approves pembrolizumab for adults and children With TMB-H solid tu [Internet]. U.S. Food and Drug Administration. FDA; [cited 2021 Jul 28]. Available from: https://www.fda.gov/drugs/drug-approvals-and-databases/fda-approves-pembrolizumab-adults-and-children-tmb-h-solid-tumorsMorris LGT, Riaz N, Desrichard A, Şenbabaoğlu Y, Hakimi AA, Makarov V, et al. Pan-cancer analysis of intratumor heterogeneity as a prognostic determinant of survival. Oncotarget 2016;7(9):10051–63.GDC. [cited 2021Jul28]. Available from: https://portal.gdc.cancer.gov/cBioPortal for cancer genomics [Internet]. cBioPortal for Cancer Genomics. [cited 2021Jul28]. Available from: https://www.cbioportal.org/Roth A, Khattra J, Yap D, Wan A, Laks E, Biele J, et al. PyClone: Statistical inference of CLONAL population structure in cancer. Nature Methods 2014;11(4):396–8.GenePattern [Internet]. GenePattern sign in. [cited 2021Jul28]. Available from: https://cloud.genepattern.org/gp/pages/index.jsfTamborero D, Gonzalez-Perez A, Lopez-Bigas N. OncodriveCLUST: Exploiting the Positional clustering of somatic mutations to identify CANCER GENES. Bioinformatics. 2013;29(18):2238–44.Mayakonda A, Lin D-C, Assenov Y, Plass C, Koeffler HP. Maftools: Efficient and comprehensive analysis of somatic variants in cancer. Genome Research 2018;28(11):1747–56.Ethics ApprovalN/AConsentN/A

Identification of stem cell-related subtypes and risk scoring for gastric cancer based on stem genomic profiling

Background Although numerous studies demonstrate the role of cancer stem cells in occurrence, recurrence, and distant metastases in gastric cancer (GC), little is known about the evolving genetic and epigenetic changes in the stem and progenitor cells. The purpose of this study was to identify the stem cell subtypes in GC and examine their clinical relevance. Methods Two publicly available datasets were used to identify GC stem cell subtypes, and consensus clustering was performed by unsupervised machine learning methods. The cancer stem cell (CSC) typing-related risk scoring (RS) model was established through multivariate Cox regression analysis. Results Cross-platform dataset-based two stable GC stem cell subtypes, namely low stem cell enrichment (SCE_L) and high stem cell enrichment (SCE_H), were prudently identified. Gene set enrichment analysis revealed that the classical oncogenic pathways, immune-related pathways, and regulation of stem cell division were active in SCE_H; ferroptosis, NK cell activation, and post-mutation repair pathways were active in SCE_L. GC stem cell subtypes could accurately predict clinical outcomes in patients, tumor microenvironment cell-infiltration characteristics, somatic mutation landscape, and potential responses to immunotherapy, targeted therapy, and chemotherapy. Additionally, a CSC typing-related RS model was established; it was strongly independent and could accurately predict the patient’s overall survival. Conclusions This study demonstrated the complex oncogenic mechanisms underlying GC. The findings provide a basis and reference for the diagnosis and treatment of GC.

Integrating magnetic capabilities to intracellular chips for cell trapping

Current microtechnologies have shown plenty of room inside a living cell for silicon chips. Microchips as barcodes, biochemical sensors, mechanical sensors and even electrical devices have been internalized into living cells without interfering their cell viability. However, these technologies lack from the ability to trap and preconcentrate cells in a specific region, which are prerequisites for cell separation, purification and posterior studies with enhanced sensitivity. Magnetic manipulation of microobjects, which allows a non-contacting method, has become an attractive and promising technique at small scales. Here, we show intracellular Ni-based chips with magnetic capabilities to allow cell enrichment. As a proof of concept of the potential to integrate multiple functionalities on a single device of this technique, we combine coding and magnetic manipulation capabilities in a single device. Devices were found to be internalized by HeLa cells without interfering in their viability. We demonstrated the tagging of a subpopulation of cells and their subsequent magnetic trapping with internalized barcodes subjected to a force up to 2.57 pN (for magnet-cells distance of 4.9 mm). The work opens the venue for future intracellular chips that integrate multiple functionalities with the magnetic manipulation of cells.

PCGF1 promotes epigenetic activation of stemness markers and colorectal cancer stem cell enrichment

Colorectal cancer (CRC) stem cells are resistant to cancer therapy and are therefore responsible for tumour progression after conventional therapy fails. However, the molecular mechanisms underlying the maintenance of stemness are poorly understood. In this study, we identified PCGF1 as a crucial epigenetic regulator that sustains the stem cell-like phenotype of CRC. PCGF1 expression was increased in CRC and was significantly correlated with cancer progression and poor prognosis in CRC patients. PCGF1 knockdown inhibited CRC stem cell proliferation and CRC stem cell enrichment. Importantly, PCGF1 silencing impaired tumour growth in vivo. Mechanistically, PCGF1 bound to the promoters of CRC stem cell markers and activated their transcription by increasing the H3K4 histone trimethylation (H3K4me3) marks and decreasing the H3K27 histone trimethylation (H3K27me3) marks on their promoters by increasing expression of the H3K4me3 methyltransferase KMT2A and the H3K27me3 demethylase KDM6A. Our findings suggest that PCGF1 is a potential therapeutic target for CRC treatment.

Mesenchymal Epithelial Transition Factor Signaling in Pediatric Nervous System Tumors: Implications for Malignancy and Cancer Stem Cell Enrichment

Malignant nervous system cancers in children are the most devastating and worrisome diseases, specifically due to their aggressive nature and, in some cases, inoperable location in critical regions of the brain and spinal cord, and the impermeable blood-brain barrier that hinders delivery of pharmaco-therapeutic compounds into the tumor site. Moreover, the delicate developmental processes of the nervous system throughout the childhood years adds another limitation to the therapeutic modalities and doses used to treat these malignant cancers. Therefore, pediatric oncologists are charged with the daunting responsibility of attempting to deliver effective cures to these children, yet with limited doses of the currently available therapeutic options in order to mitigate the imminent neurotoxicity of radio- and chemotherapy on the developing nervous system. Various studies reported that c-Met/HGF signaling is affiliated with increased malignancy and stem cell enrichment in various cancers such as high-grade gliomas, high-risk medulloblastomas, and MYCN-amplified, high-risk neuroblastomas. Therapeutic interventions that are utilized to target c-Met signaling in these malignant nervous system cancers have shown benefits in basic translational studies and preclinical trials, but failed to yield significant clinical benefits in patients. While numerous pre-clinical data reported promising results with the use of combinatorial therapy that targets c-Met with other tumorigenic pathways, therapeutic resistance remains a problem, and long-term cures are rare. The possible mechanisms, including the overexpression and activation of compensatory tumorigenic mechanisms within the tumors or ineffective drug delivery methods that may contribute to therapeutic resistance observed in clinical trials are elaborated in this review.