Tumor RNA Sequencing Research Articles

Abstract 5466: In vivo characterization of neuroblastoma intratumoral heterogeneity

Abstract Background: Neuroblastoma is a pediatric solid tumor that arises from neural crest-derived progenitor cells of the peripheral sympathetic nervous system (PSNS). Neuroblastoma patients display a significant level of genetic and phenotypic heterogeneity, with amplification of the MYCN oncogene associated with poor clinical outcomes. To better understand underlying genetic mechanisms associated with aggressive neuroblastoma, our group incorporated patient-relevant loss-of-function mutations into the established MYCN-driven zebrafish model of neuroblastoma (Tg(dbh:EGFP-MYCN)), which resulted in increased tumor penetrance and a highly metastatic phenotype. Aims & Methods: We aimed to investigate metastases-associated intratumoral heterogeneity in vivo using our patient-relevant metastatic zebrafish models, with functional validations performed using human neuroblastoma cell lines. Results: Single-cell RNA sequencing of metastatic zebrafish neuroblastoma tumors revealed intra-tumor cell heterogeneity, with a subset of cells highly expressing markers of more differentiated adrenergic-like cell fates (th, dbh, phox2a) while others enriched for markers of less differentiated mesenchymal-like progenitor cells (prrx1a, vim, fn1a). Differential cell labeling in zebrafish neuroblastoma suggests distinct tumor cell populations for follow-up validation and characterization throughout metastatic progression. Conclusion: Single-cell RNA sequencing of zebrafish metastatic neuroblastoma showed evidence of intratumoral heterogeneity that warrants further investigation. We are characterizing neuroblastoma intratumoral heterogeneity in our in vivo metastatic zebrafish models to examine the association between neuroblastoma tumor composition and metastatic potential. Altogether, this work aims to improve our understanding of the evolution of tumor cell heterogeneity associated with neuroblastoma metastasis and uncover novel therapeutic opportunities to improve patient outcomes. Citation Format: Willow R. Squires, Alex Weiss, Sarah Cohen-Gogo, Adam Shlien, David Kaplan, Meredith S. Irwin, Madeline N. Hayes. In vivo characterization of neuroblastoma intratumoral heterogeneity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5466.

Abstract 762: The combination of EPA and naproxen suppresses colon tumorigenesis via altering the TME, and promoting epithelial maturation in cancerous crypts

Abstract Introduction: Colorectal cancer (CRC) is a leading cause of cancer-associated mortality. Our recent study in Pirc rats revealed that the combination of eicosapentaenoic acid and sodium naproxen exhibited additive tumor protection. While the results from this preclinical study were impressive, showing tumor suppression in excess of 95%, potential mechanisms underlying this tumor protection remain unclear. The purpose of this study was to determine the transcriptomic changes resulting in the tumor suppression afforded by the combination of EPA and naproxen supplementation in the diet. Methods: Six week-old Pirc rats were fed either a control AIN-93G diet, or AIN-93G diet supplemented with 2% EPA combined with 200 ppm naproxen, for a total of 20 weeks. Global transcriptomic analysis was performed using RNA sequencing (RNA-Seq) of colon tumors and tumor-adjacent normal tissue from 26-week-old Pirc rats. 100-bp paired-end sequencing was performed on an Illumina NovaSeq to a depth of 25 million reads per sample. Reads were trimmed with Trimmomatic-v0.39, and reads were mapped to the mRatBN7.2.105 rat reference genome using HISAT2. Differentially expressed genes were calculated using DESeq2, and gene set enrichment analysis (GSEA) were performed using Rstudio. Results: DESeq2 identified 809 differentially expressed genes (DEGs, 2-fold change > 1, FDR < 0.05) between large tumors from AIN-93G fed rats versus suppressed tumors from rats fed the combination of EPA and naproxen (490 up-regulated, 319 down-regulated). GSEA analysis revealed activation of inflammatory pathways including IL-17 signaling, JAK-STAT signaling, complement activation, cytokine signaling, ribosome biogenesis, and cell cycle were enriched in untreated control. In contrast, suppressed tumors from animals supplemented with EPA and naproxen were enriched in pathways including negative regulation of Wnt signaling, cell fate specification, ion channel complexes, and nutrient absorption. Furthermore, suppressed tumors shared significant GSEA pathway overlap with normal tissue, leading us to believe the combination of EPA and naproxen may be preventing tumorigenesis in part by maintaining cells in a differentiated state. Conclusion and Future directions: Inflammation plays a key role in tumorigenesis and promoting cancer stem cell niches in tumors. According to our analysis, the combination of EPA and naproxen attenuated cancer-associated inflammation and reduced proliferation in part by augmenting tumor differentiation. Future studies will utilize single-nuclei RNA-Seq (snRNA-Seq) to determine at a single cell resolution the transcriptomic changes of epithelial and stromal populations within the TME. This work was supported by National Cancer Institute task order 75N91019F00132. Citation Format: Ryan Beach, Michael Martinez, Vignesh Gunasekharan, Daniel W. Rosenberg. The combination of EPA and naproxen suppresses colon tumorigenesis via altering the TME, and promoting epithelial maturation in cancerous crypts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 762.

Abstract 4032: ATRA induces an interferon response to reprogram the immunosuppressive tumor microenvironment and overcomes resistance to immune checkpoint inhibition in murine models of LKB1-deficient non-small cell lung cancer

Abstract Lung cancer remains the deadliest form of cancer, claiming 1.8 million lives worldwide in 2020. While treatment options have improved with the advent of immune checkpoint inhibitors (ICI), many patients do not respond to immunotherapy or develop resistance following initial response. A significant subset of non-small cell lung cancer (NSCLC) patients harbors somatic co-mutations in Kirsten rat sarcoma virus (KRAS) and Liver kinase 1 [LKB1, also known as serine/threonine kinase 11 (STK11)] genes, whose tumors are characterized by an immunosuppressive tumor microenvironment (TME) that are resistant to ICI. Our studies revealed that all-trans retinoic acid (ATRA), a metabolite derived from vitamin A, sensitized a murine model of NSCLC with increased tumor mutational burden (Kras G12D P53-/-Lkb1-/-; KPL-3M) to PD-1 blockade. The ATRA and anti-PD-1 combination therapy improved local and systemic T cell activation and generated systemic tumor-specific immunity. To understand ATRA-mediated anti-tumor effects, we performed single cell RNA sequencing (scRNA-seq) of KPL-3M murine tumors with or without 6 daily ATRA treatments. scRNA-seq analysis revealed a reduction of neutrophils as well as an enrichment in T cell and natural killer (NK) cell populations in the TME. Furthermore, scRNA-seq analysis revealed elevated expression of interferon (IFN) downstream genes in multiple immune subpopulations in the TME. Preliminary ex vivo studies indicated that ATRA increases NOX2 levels, intracellular reactive oxygen species (ROS), and IFN signaling in the neutrophils in KPL-3M tumors. Our findings suggest that ATRA may reshape the TME by activating IFN signaling in multiple cell subtypes to sensitize resistant tumors to ICI immunotherapy. Citation Format: William P. Crosson, Rui Li, Ramin Salehi-Rad, Raymond J. Lim, Jensen Abascal, Bitta P. Kahangi, Edgar Perez Reyes, Michael Oh, Camelia Dumitras, Nico Edgar, Ryan Chew, Rashel Jocobo, Adam Tfayli, Zhe Jing, Kostyantyn Krysan, Linh Tran, Steven M. Dubinett, Bin Liu. ATRA induces an interferon response to reprogram the immunosuppressive tumor microenvironment and overcomes resistance to immune checkpoint inhibition in murine models of LKB1-deficient non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4032.

Abstract 3050: Evaluating the role of ∆Np63α in driving growth and metastasis of pancreatic ductal adenocarcinoma

Abstract Pancreatic ductal adenocarcinoma (PDAC) is the third leading cause of cancer-related deaths in the US and is rising in incidence. PDAC tumors may be either classical or basal in transcriptomic subtype, and PDAC patients with basal tumors have worse prognosis and may have increased resistance to chemotherapy. Previous studies have shown that ∆Np63α drives basal program expression. The goal of this project is to investigate whether ∆Np63α expression is sufficient to increase pancreatic cancer cell growth, metastasis and chemoresistance and whether these cells can outcompete ∆Np63α non-expressers in mixed tumors. Non-∆Np63α expressing human PDAC cell lines AsPC1 and HPAFII were stably transduced to express either ∆Np63α or mCherry (control). For both AsPC1 and HPAFII, ∆Np63α-expressing and control cells had similar proliferation rates and susceptibility to chemotherapy agents oxaliplatin and SN38 when grown in culture. When control or ∆Np63α-expressing AsPC1 cells were implanted orthotopically into the pancreas of athymic nude mice, there was no significant difference in primary tumor mass and pathological analysis of lungs and livers did not reveal any significant difference in metastatic burden. Bulk RNA sequencing of primary tumors confirmed that tumors in mice inoculated with AsPC1-∆Np63α had significantly upregulated expression of genes associated with the basal subtype. Collectively, these data suggest that while ∆Np63α drives the basal program in PDAC, its expression is insufficient to cause resistance to these chemotherapies or a growth or metastatic advantage in an immunodeficient setting. Further work is needed to elucidate the mechanism by which ∆Np63α contributes to more aggressive PDAC tumors. Citation Format: Daniel H. Ryan, Chin-Hsien (Emily) Tai, Xianyu Zhang, Mayrel Palestino Dominguez, Christine Alewine. Evaluating the role of ∆Np63α in driving growth and metastasis of pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3050.

Abstract 1803: ACOD1 is a key regulator of immunosuppressive MDSCs, prostate cancer progression, and resistance to immunotherapy

Abstract Although Immune checkpoint therapy (ICT) is highly effective in a wide range of malignancies, patients with metastatic castration-resistant prostate cancer (mCRPC) are largely resistant to ICT. Yet, the cellular and molecular basis of the poor response to ICT in lethal prostate cancer remain poorly defined. Polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) have emerged as a key driver of prostate cancer progression and resistance to immunotherapy. Yet the molecular mechanisms underlying the immunosuppressive activities of PMN-MDSCs remains poorly defined. By performing single-cell RNA-sequencing (scRNA-seq) of prostate tumors, we identified Acod1, a gene that encodes cis-aconitate decarboxylase (ACOD1) and catalyzes the synthesis of itaconate from cis-aconitate in the tricarboxylic acid (TCA) cycle, is among the top 5 metabolic-related genes that are overexpressed in PMN-MDSCs. Moreover, bulk RNA-seq and microarray datasets revealed that intratumoral and splenic PMN-MDSCs express a significantly higher level of Acod1 compared to less immunosuppressive bone marrow PMN-MDSCs. Importantly, high ACOD1 expression is strongly associated with significantly shorter overall survival and higher Gleason scores in human mCRPC. Using an autochthonous whole-body Acod1-KO mouse model, we showed that Acod1 KO in TRAMP mice led to a reduction in tumor burden and an increase in overall survival. Furthermore, using syngeneic prostate cancer models, we showed that whole-body or PMN-specific Acod1-KO delayed tumor progression. As expected, Acod1 KO dramatically reduced the production of itaconate in bone marrow-derived MDSCs (BM-MDSC) as shown by targeted metabolic profiling. Importantly, we found that Acod1 KO impaired immunosuppressive activities of BM-MDSC and an increase in CD3+ and CD8+ T cell infiltration in the tumors. Also, Acod1-KO in BM-MDSC led to a reduction of H2DCFDA staining intensity suggesting a reduction in the production of reactive oxygen species (ROS). Gene set enrichment analysis (GSEA) revealed that Acod1-KO MDSCs have hyperactive oxidative phosphorylation (OXPHOS) compared to Acod1-WT BM-MDSCs. KO of Acod1 also leads to suppression of key MDSC functions signaling such as TNFα/NFκB, IL6/JAK/STAT3, and C/EBPβ pathways. In summary, our data suggests that the upregulation of ACOD1 in PMN-MDSCs has a vital role in prostate cancer progression and resistance to ICT by regulating their immunosuppressive activities through metabolic reprogramming. Also, our data suggest that targeting ACOD1 could be an effective therapeutic strategy for lethal prostate cancer as a monotherapy and in combination with immunotherapy. Citation Format: Celia Sze Ling Mak, Xin Liang, Jessica Suh, Derek Liang, Ming Zhu, Guocan Wang. ACOD1 is a key regulator of immunosuppressive MDSCs, prostate cancer progression, and resistance to immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1803.

Abstract 5301: Tumor-targeted activation of CD137 using Bicycles: New insights into mechanism of action and discovery of BT7455, a clinical candidate for the treatment of EphA2-expressing cancers

Abstract Introduction: Clinical studies in cancer patients have validated CD137 agonism as an activator of the immune system to enable tumor rejection. We have demonstrated that small, chemically synthetic bicyclic peptides can drive tumor-localized agonism of CD137 and anti-tumor immunity in mouse models. Here, we report the next stage of our work - delving into the mechanism of action of these novel agents and extending our program to serve patients whose tumors express EphA2. Experimental Procedures: MultiOmyx™ hyperplexed immunofluorescence assay was used to evaluate the expression of CD137 and EphA2 in head and neck squamous cell carcinoma samples. Human PBMC/tumor cell co-culture assays were used to assess CD137 Bicycle TICA™ in vitro bioactivity and syngeneic mouse tumor models were used to evaluate CD137 Bicycle TICA anti-tumor activity as mono- or combination therapies. Pharmacodynamic activity was evaluated by transcriptional profiling using NanoString assays or single cell RNA sequencing. Summary of the Data: Studies utilizing a syngeneic mouse model and deep RNA sequencing of tumors from CD137 Bicycle TICA-treated mice implicated intratumoral dendritic cells in addition to T cells as early responders to localized CD137 agonism and potential contributors to the anti-tumor response. Furthermore, a mouse efficacy model demonstrated synergy with checkpoint inhibitor therapy. Multiplex imaging revealed that EphA2 and CD137 are co-expressed in human tumors of high unmet medical need and therefore, using our highly modular Bicycle platform, we discovered BT7455, a Bicycle TICA that engages EphA2 and CD137 with high affinity, resulting in potent EphA2-dependent activity in vitro and robust anti-tumor activity in vivo with intermittent dosing in mouse models. Gene expression profiling of tumors revealed that BT7455 led to increased production of cytokines and chemokines known to drive T cell infiltration, the extent of which differentiated it from both a checkpoint inhibitor and an anti-CD137 monoclonal antibody agonist. BT7455 was well tolerated in preclinical species and liver function tests indicated no evidence of hepatic toxicity. Statement of Conclusions: In summary, we have identified EphA2 as a promising target to pair with a CD137 agonist. In addition to CD8+ T cells, tumor-resident dendritic cells are a likely contributor to anti-tumor immunity following treatment with Bicycle® TICAs, supporting utility for Bicycle® tumor-targeted CD137 agonists in solid tumors beyond those that are highly T cell-infiltrated. We have advanced a clinical development candidate, BT7455, to realize this potential for patients with EphA2-expressing cancers. Citation Format: Johanna Lahdenranta, Kristen Hurov, Heather Cohen, Lia Luus, Cara Bray, Peter Brown, Anna Devlen, Carly Campbell, Matthew Gray, Mike Kelly, Gemma Mudd, Punit Upadhyaya, Sailaja Battula, Kelvin Zhang, Anne-Sophie Dugast, Kevin McDonnell, Phil Brandish, Nicholas Keen. Tumor-targeted activation of CD137 using Bicycles: New insights into mechanism of action and discovery of BT7455, a clinical candidate for the treatment of EphA2-expressing cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5301.

Abstract 716: Depletion of stromal cells remodels tumor microenvironment and potentiates immune checkpoint blockade in pancreatic cancer

Abstract During carcinoma progression, mesenchymal stromal cells (MSCs) become recruited to tumors and contribute to the pool of cancer-associated fibroblasts (CAFs). Sub-populations of CAFs, have diverse and incompletely understood effects on disease progression and resistance to therapy. Adipose stromal cells (ASCs), the MSCs from fat tissue increasingly recruited by carcinomas in the context of obesity, have been shown to support cancer progression. Here, the roles of perivascular CAFs expressing platelet-derived growth factor receptor beta (Pdgfrb) and of CAFs expressing non-glycanated decorin (ngDCN), a marker of ASCs, were analyzed. We used mice orthotopically grafted with pancreatic ductal adenocarcinoma (KPC) cells. Ablation of cells expressing thymidine kinase under the control of Pdgfrb promoter with ganciclovir resulted in suppression of primary pancreatic tumor growth. However, ablation Pdgfrb+ cells induced spontaneous metastases to the liver. For depletion of ngDCN+ cells, we used a hunter-killer peptide D-CAN, which has been previously reported to induce apoptosis of ASCs and CAFs in mouse models. Here, D-CAN also had a negative effect on pancreatic tumor growth, however, there was no significant effect on metastatic dissemination. Single cell RNA sequencing of tumors demonstrated that targeting of Pdgfrb+ and ngDCN+ stromal cells had distinct effects on sub-populations of CAFs. Endothelial cell and cancer cell survival was decreased by depletion of either Pdgfrb+ or ngDCN+ stroma. However, pathway analysis revealed that depletion of Pdgfrb+ and ngDCN+ stromal cells has different effects on the markers of cancer cell aggressiveness. D-CAN treatment, and to a less extent Pdgfrb+ cell ablation, suppressed macrophage M2 polarization and increased infiltration of cytotoxic T-lymphocytes. This observation, confirmed in the MyCap graft model of prostate cancer, suggested that ablation of ngDCN+ stroma should synergize with immune checkpoint inhibitors. We tested the effect of D-CAN on the efficacy of anti-PDL1 antibody in the orthotopic KPC model. Compared to D-CAN and anti-PDL1 antibody alone, combination treatment had a synergistic effect on tumor growth. Importantly, liver metastases were suppressed by the D-CAN/anti-PDL1 antibody combination, but not by individual agents. We conclude that improved approaches to target mesenchymal stroma in tumors may be effective in combination with immunotherapy. Citation Format: Joseph Rupert, Alexes Daquinag, Lingyi Cai, Yulin Dai, Zhongming Zhao, Dimitris Anastassiou, Mikhail Kolonin. Depletion of stromal cells remodels tumor microenvironment and potentiates immune checkpoint blockade in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 716.

Abstract 4291: Bai1 inhibition promotes ferroptosis of breast cancer cells to prevent tumor growth in human xenograft tumor models

Abstract The adhesion G-protein coupled- receptor 1 ADGRB1/Bai1 was identified as a phosphatidylserine receptor that cooperates with ELMO/Dock180/Rac to promote maximal engulfment of apoptotic cells. This function of Bai1 was also shown to promote myoblasts fusion. Cell-cell fusion has been demonstrated to occur in normal physiological functions as well as in diseases. Studies have shown in cancer that cell-cell fusion increases tumor heterogeneity, drug resistance, and metastasis as hybrids acquire new properties that allow them to migrate and proliferate at new sites. Activation of ELMO-Dock signaling pathway has been associated with breast cancer metastasis. Moreover, ELMO1 has been identified as a modifier of breast cancer risk for BRCA mutation carriers. Rac1 was also shown to be overexpressed in proliferative breast disease, preinvasive and invasive breast carcinoma as well as lymph node metastases. Our recent studies showed that breast cancer cell fusion with bone marrow-derived mesenchymal stem cells was modulated by hypoxic conditions and promoted by apoptosis. Our hypothesis is that hypoxia stress induced apoptosis activates the phosphatidylserine receptor Bai1, and it signals through the ELMO/DOCK180/Rac to promote breast cancer cell fusion-driven tumor heterogeneity and metastasis. In this study, we determined the ability of Bai1 depleted breast cancer cells to induce tumor growth in immunocompromised mice. We used Bai1 sgRNA to inhibit Bai1 expression in the breast cancer cell MDA-MB-231. These cells (1x 106) together with bone marrow-derived mesenchymal stem cells (MSCs) (1x 106) were injected into the fat pad of the breast of 15 NOD SCID female mice. Control mice (15) received the same cells with no inhibition of Bai1. The mice were monitored for eight weeks. We found that Bai1 inhibition significantly reduced tumor growth in these mice in the course of time (P<0.05). The average tumor weight was also significantly reduced when Bai1 was inhibited (P<0.001). RNA sequencing of tumors generated from these mice revealed a significant increase in the expression of genes driving ferroptosis and a reduction in critical oncogenes in the experiment group compared to the control group. These findings will be helpful in the development of new classes of drugs effective in breast cancer treatment. Grant Support The NIH/NIMHD grant 5U54MD015929-03, the Society for Investigative Dermatology (SID) Freinkel Diversity Fellowship, and NSF Award Notice for Award ID 2142465 (awarded to FNK). Citation Format: Felicite Kamdem Noubissi, Oluwatowin Odubanjo, Hung-Chung Huang, Brenda Ogle, Paul Tchounwou. Bai1 inhibition promotes ferroptosis of breast cancer cells to prevent tumor growth in human xenograft tumor models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4291.

Abstract 5610: Investigating the role of BRCA2 in the development of pediatric rhabdomyosarcoma

Abstract Introduction: In a large-scale exome sequencing study of pediatric rhabdomyosarcoma (RMS) patients, we identified a statistical enrichment of patients with germline variants in BRCA2 (Li, et al. JNCI, 2020), which prompted this study to assess the role of heterozygous BRCA2 variants in the development of pediatric RMS in both precursor cell and mouse models. Methods: We engineered BRCA2 loss of function (LoF) variants in lines of immortalized mesenchymal stem cells, a potential precursor cell to RMS, using CRISPR and Prime Editing (PE). CRISPR was used to induce frameshift alleles in Exons 10 and 11 and with PE, we created two RMS patient specific LOF variants in Exons 5 and 17. We generated a genetically engineered mouse model (GEMM) with heterozygous excision of Exon 11 of Brca2. This allele is now being crossed into two different previously established GEMMs of RMS: a myoblast-specific (MyoD1-Cre) conditional loss of p53, and a gain-of-function mutant p53, LSL-p53R172H (Nakahata, et al. Dis. Model. Mech., 2022), to assess changes in the pace of tumorigenesis and metastatic potential. Through an X01 agreement with the Gabriella Miller Kids First Program, we have submitted paired tumor-normal samples for additional whole-genome sequencing and RNA sequencing (tumor only) on >500 patients with RMS, including those with germline variants in BRCA2. Results: Using CRISPR, we generated cell lines heterozygous for the frameshift variants c.1345dup, c.5680del, and c.5680dup. With Prime Editing, we created heterozygous lines mimicking two specific variants detected in the RMS cohort, c.462_463del and c.7857G>A. Generation of a C57BL6 GEMM with a heterozygous removal of Exon 11 in Brca2 has been successful. No homozygous mice were obtained following 7 heterozygous crosses (50 pups), a departure from Mendelian ratios (p=0.0001) consistent with embryonic lethality. Heterozygous Brca2 mice derived from crosses into two RMS models are being monitored for tumor development. We have completed tumor-normal whole-genome and tumor RNA sequencing for 609 RMS patients, including 228 subjects not previously analyzed. We will directly assess whether there is evidence for mutation or loss of expression of the remaining BRCA2 allele in tumors and whether these tumor genomes exhibit signatures of DNA repair deficiency. Conclusions: The goal of this project is to determine the molecular basis for the enrichment in germline BRCA2 LOF variants in pediatric malignancies, including RMS. Ongoing experiments using the engineered heterozygous BRCA2 in vitro cell line models will assess genomic stability, homologous recombination proficiency, and DNA replication fork stability. Assessment of the effect of heterozygous Brca2 variants in GEMMs of RMS, and subsequent analysis of additional sequencing data, will further elucidate what role this gene may play in increasing risk or progression of pediatric cancers. Citation Format: P. Adam Weinstein, Ryan Zabriskie, Cem Ozdemir, Kyle M. Miller, Olga Medina-Martinez, Jason D. Heaney, Aniko Sabo, Philip J. Lupo, Sharon E. Plon. Investigating the role of BRCA2 in the development of pediatric rhabdomyosarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5610.

Abstract 6556: Targeting mesenchymal tumor cell-intrinsic factors sensitizes refractory tumors to immune checkpoint blockade therapy

Abstract Immune checkpoint blockade (ICB) therapy has emerged as a promising approach for treating breast cancer, however, only a fraction of patients derives clinical benefit and the underlying reasons for heterogeneous responses remain elusive. The epithelial-to-mesenchymal transition (EMT) enables these carcinomas to metastasize and acquire resistance to chemotherapy. We have recently demonstrated that the EMT program also confers resistance to immunotherapies. Specifically, epithelial tumors recruit CD8+ T-cells to the tumor microenvironment and are sensitive to anti-CTLA4 ICB. In contrast, mesenchymal tumors assemble an immunosuppressive tumor microenvironment and are resistant to the same treatment. Furthermore, mesenchymal tumors express multiple immunosuppressive paracrine factors relative to their epithelial counterparts. Of these, abrogation of CSF1 or SPP1 from mesenchymal cancer cells generates partial responses to ICB therapy. Strikingly, abrogation of CD73 from mesenchymal carcinoma cells completely sensitizes otherwise refractory tumors to immunotherapy. While targeting cancer cell-intrinsic factors can sensitize mesenchymal tumors to ICB, the mechanisms that dictate partial versus complete responses are unclear. Furthermore, whether abrogation of CD73 can also sensitize mesenchymal tumors to other forms of ICB remains unknown. By performing immunofluorescent analysis of tumor sections, we observed that knockout of CD73 promoted the greatest infiltration of both CD4+ and CD8+ T-cells in response to anti-CTLA4 ICB compared to tumors knocked out for CSF1 and SPP1, which showed only intermediate levels of infiltration. Moreover, treatment of mesenchymal tumor-bearing mice with anti-CD73 generated synergistic responses with anti-CTLA4 ICB, but not with anti-PD1, or combinations of anti-CTLA4 and anti-PD1. In conclusion, our results demonstrate that the EMT program in cancer cells is predictive of responses to ICB. Targeting CD73 in mesenchymal breast tumors promotes an influx of both CD4+ and CD8+ T-cells and potentiates the efficacy of anti-CTLA4 ICB. Through mining of canine mammary tumor RNA sequencing data, we have found that canine tumors associated with EMT have increased expression of CD73, which suggests that these mechanisms of immune evasion may translate across species. These findings could promote therapies for both animals and humans that sensitize highly refractory populations of more-mesenchymal cancer cells. Citation Format: Kimaya M. Bakhle, Caitie H. Sams, Anushka Dongre. Targeting mesenchymal tumor cell-intrinsic factors sensitizes refractory tumors to immune checkpoint blockade therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6556.

Abstract 1560: In vivo CRISPR/Cas9 transcriptional activation screen leads to discovery of INAFM2, a novel driver of metastasis

Abstract Metastasis is the main cause of mortality in cancer patients and accounts for about 90% of cancer deaths, which has not changed in the past 50 years. This indicates a significant need for further study of metastasis pathways to find novel druggable targets. Ewing sarcoma (ES) is an aggressive childhood cancer that occurs in the bones or soft tissue. The five-year survival rate for Ewing sarcoma patients diagnosed with metastatic disease is still only 25%, making ES a good model for studying metastasis. We performed a genome-wide CRISPR/Cas9 transcriptional activation screen in a zebrafish xenograft model to discover genes whose activation leads to increased metastasis. The screen identified a number of genes that may accelerate ES metastasis; we chose INAFM2 for further study because multiple unique INAFM2-targeting gRNAs were enriched in the screen and we discovered a potential link to metastasis and patient survival in publicly available clinical data. Overexpression of INAFM2 in six different cancer cell lines (four ES, one hepatocellular carcinoma, and one stomach adenocarcinoma) caused increased cell migration and chemotaxis in vitro, and increased intravasation in zebrafish xenografts. INAFM2 knockdown in four cancer cell lines (two ES, one clear cell renal cell carcinoma, and one stomach adenocarcinoma) decreased chemotaxis and rescue of INAFM2 expression restored the cells’ ability to migrate. Analysis of patient tumor RNA sequencing data from many different types of cancers revealed correlations between INAFM2 expression and both an increased metastatic phenotype and poor patient survival. Further in vivo studies by tail vein injection of ES cells in immunodeficient mice demonstrated significantly increased gross metastases with INAFM2 overexpression and decreased gross metastases with INAFM2 knockdown compared to the respective control groups. This provides strong evidence for a substantial role of INAFM2 in cancer metastasis. Human INAFM2 is an unstudied gene and our preliminary work has revealed that the INAFM2 protein localizes to the cell membrane, is glycosylated, and may be involved in Wnt and/or MAPK pathway signaling. Inafm2 silencing by morpholino in zebrafish embryos lead to significant mortality, necrosis, and developmental delays/defects including severe cardiac edema. Current studies are focused on further discerning the molecular pathways that mediate the role of INAFM2 in promoting metastasis using in vitro and in vivo models as well as characterizing the functional significance of the direct protein binding partners and post-translational modifications for INAFM2. Citation Format: Anna Molotkova, Emre Deniz, Matthew Swift, Eric Glasgow, Jeffrey Toretsky, Aykut Üren. In vivo CRISPR/Cas9 transcriptional activation screen leads to discovery of INAFM2, a novel driver of metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1560.

Abstract 7647: Identification of transcriptional plasticity biomarkers for patient stratification

Abstract Biomarker signatures associated with disease progression are important tools for the management of patient care. However, such signatures are frequently indication-specific, which limits their utility to stratify broader populations. Transcriptional plasticity, the ability of a transcriptome to change in response to external stimuli, is of interest due to its relation to disease progression and therapeutic response. To extend and generalize the measurement of a patient’s risk of disease progression to a pan-cancer, sequencing-based biomarker, Emax, the maximum cytotoxicity of a compound in a cell line, was explored as a potential universal marker of transcriptional plasticity. To explore correlation between Emax and transcriptional plasticity, cancer cell lines were ranked by mean Emax across multiple classes of cytotoxic compounds analyzed in GDSC (Yang et. al., 2013). Cell lines with lower Emax (more surviving cells at high drug concentrations) were filtered to exclude cell lines which tended to have higher IC50 values to remove cell lines that may be generally more resistant. With GDSC1 as the train set and GDSC2 as the test set, differentially expressed genes between high-Emax and low-Emax cell lines were selected for further analysis and possible inclusion in the plasticity biomarker signature. Test analysis in GDSC2 revealed an R2 of 0.88 suggesting transferability. For clinical validation, public repositories were queried for tumor RNA sequencing data with paired response data. To avoid batch effects between experiments, preliminary validation focused on one sufficiently large dataset with well-curated response data (n = 170; Barrett et. al., 2013, GSE91061; phs000452.v1.p1). Analysis of the expression of the genes identified in the in vitro signature revealed significant differential expression between patients who were reported as having an objective response and patients who achieved stable disease as best response. In silico pathway analysis of this signature revealed enrichment in cell-cell adhesion, signaling, and gene regulation, which relate to the hallmarks of phenotypic plasticity and epigenetic reprogramming (Hanahan, 2022). This analysis reveals similarity between gene expression patterns associated with Emax measured in vitro and transcriptional plasticity in the clinic. Additional experimentation is underway to prospectively analyze this set of biomarkers and to retrospectively validate this signature in additional datasets with the goal of patient stratification by the risk of disease progression following an initial, incomplete response to therapy. Citation Format: Jeremy Goldstein, Christina Gavazzi, Mikhail Grushko, Mahta Samizadeh, Zakary ElSeht, Katherine Arline. Identification of transcriptional plasticity biomarkers for patient stratification [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7647.

Abstract B082: A pro-tumorigenic, aged microenvironment may aid in worsened disease progression in an HGSOC model

Abstract Over 70% of HGSOC patients are diagnosed after 55 and the average patient succumbs to disease at 70 years old. Despite this, most ovarian cancer research, and cancer studies generally, utilize young mice that are mimetic of human teenagers and/or do not investigate age as a variable despite it being the top cancer risk factor. An improved understanding of how age affects HGSOC progression may enable development of alternative treatment strategies aimed at intercepting metastasis and preventing cancer cells from establishing in the peritoneum. Our preliminary studies show tumor burden and disease severity are significantly higher in aged versus young animals. We developed an epithelial cell line derived from C57Bl/6 oviducts and used CRISPR-Cas9 genome editing to develop a syngeneic tumorigenic line harboring Trp53, Pten, and Brca2 deletions. After intraperitoneal injection into 6-week and 14-month-old immunocompetent C57Bl/6 mice, we observed a stark increase in tumor burden in aged mice. Furthermore, older mice died at a faster rate; all aged mice succumbed to disease within 1-month of inoculation compared to young mice surviving up to 3 months. Total RNA-sequencing of tumors harvested from aged and young mice is ongoing. Characterization of the tumor-naïve peritoneal compartment revealed the aged microenvironment to be highly inflammatory. When assessed via cytokine array, peritoneal fluid of aged mice had higher concentrations of inflammatory markers including soluble TNF receptor-1 (sTNFR-1), L-selectin, and VCAM-1. Flow cytometry of peritoneal lavage indicated an over 2-fold increase in the number CD45+ cells present in the peritoneal cavity, coinciding with cytokine array results. Within this population, there was nearly complete depletion of macrophage and neutrophil populations and a significant increase in B cells and CD4+ and CD8+ T cells. The percentage of PD-1+ CD8+ cells also increased. In addition to increased signs of inflammation, a significantly higher concentration of insulin-like growth factor-1 (IGF-I) and higher concentrations of the associated IGF binding proteins -3 and -6 were found in peritoneal fluid of aged mice. In addition, during tissue collection, organs of the aged mice were found to be much larger than young mice, a common effect of elevated IGF-I; aged omentum weighed 2-4 times that of young. Notably, IGF-I is known to inhibit apoptosis and promote proliferation and increased IGF-I is correlated with increased risk of breast, prostate, and lung cancer. A drastic difference in disease severity occurs when identical cancer cells are injected into 6-week and 14-month-old mice. To identify possible microenvironmental differences in the two populations, a broad panel of cytokines was assessed, and immune populations were quantified in pre-cancerous mice. Overall, multiple pro-inflammatory markers and the number of lymphocytes were upregulated in the aged peritoneal cavity, and markers of immune fatigue were present. Further work is aimed at identifying immune cell state via further cytometry and sequencing. Citation Format: Katherine A. Cummins, Ronny I. Drapkin, Matthew Knarr. A pro-tumorigenic, aged microenvironment may aid in worsened disease progression in an HGSOC model [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr B082.

Multiomic molecular characterization of the response to combination immunotherapy in MSS/pMMR metastatic colorectal cancer

BackgroundImmune checkpoint inhibitor (ICI) combinations represent an emerging treatment strategies in cancer. However, their efficacy in microsatellite stable (MSS) or mismatch repair-proficient (pMMR) colorectal cancer (CRC) is variable. Here, a...

Transcriptomic Analysis of Metastatic Colorectal Tumor with Low Mutational Burden

Objective: To identify potential drug targets for metastasis colorectal cancer (CRC) patients with low mutational burden by examining differences in immune-related gene expression. Methods: For this study, 623 samples were collected from The Cancer Genome Atlas (TCGA) database, comprising tumor mutational burden (TMB), RNA sequencing (RNA-Seq), and clinical data. Differential gene expression analysis, Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of the identified genes were conducted using the R package. Additionally, a comparative analysis of immune infiltrating cell composition in metastatic and non-metastatic groups was performed. Hub genes, exhibiting high levels of interaction, were selected using the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database. The Drug Gene Interaction Database (DGIdb) was then utilized to estimate drugs targeting the identified hub genes. Results: The transcriptome data of 326 colorectal cancer patients with low TMB were analyzed, comprising 58 patients with metastasis and 268 patients without metastasis. Among the differential expression in 1,111 genes for patients with metastasis compared to those without metastasis, 733 genes were upregulated, and 378 genes were downregulated. KEGG and GO enrichment analysis indicated significant differences in gene expression in CRC metastatic patients with low TMB compared to non-metastasis patients with low TMB. Enriched pathways included humoral immuneresponse, immunoglobulin production, and regulation of AMPA receptor activity. Two genes related to interleukin-12 were identified through secondary enrichment for immune-related genes. Analysis of tumor-infiltrating immune cell data revealed significant differences in memory-activated T cell CD4 and T cell CD8. Conclusions: This analysis of RNA sequencing data and immune-filtrating cell data revealed significant differences between metastatic colorectal cancer patients with low TMB and their non-metastatic counterparts. These distinctions suggest the possibility of identifying more effective drugs or therapies for metastatic colorectal cancer patients with low TMB.

Divergent HLA variations and heterogeneous expression but recurrent HLA loss-of- heterozygosity and common HLA-B and TAP transcriptional silencing across advanced pediatric solid cancers.

The human leukocyte antigen (HLA) system is a major factor controlling cancer immunosurveillance and response to immunotherapy, yet its status in pediatric cancers remains fragmentary. We determined high-confidence HLA genotypes in 576 children, adolescents and young adults with recurrent/refractory solid tumors from the MOSCATO-01 and MAPPYACTS trials, using normal and tumor whole exome and RNA sequencing data and benchmarked algorithms. There was no evidence for narrowed HLA allelic diversity but discordant homozygosity and allele frequencies across tumor types and subtypes, such as in embryonal and alveolar rhabdomyosarcoma, neuroblastoma MYCN and 11q subtypes, and high-grade glioma, and several alleles may represent protective or susceptibility factors to specific pediatric solid cancers. There was a paucity of somatic mutations in HLA and antigen processing and presentation (APP) genes in most tumors, except in cases with mismatch repair deficiency or genetic instability. The prevalence of loss-of-heterozygosity (LOH) ranged from 5.9 to 7.7% in HLA class I and 8.0 to 16.7% in HLA class II genes, but was widely increased in osteosarcoma and glioblastoma (~15-25%), and for DRB1-DQA1-DQB1 in Ewing sarcoma (~23-28%) and low-grade glioma (~33-50%). HLA class I and HLA-DR antigen expression was assessed in 194 tumors and 44 patient-derived xenografts (PDXs) by immunochemistry, and class I and APP transcript levels quantified in PDXs by RT-qPCR. We confirmed that HLA class I antigen expression is heterogeneous in advanced pediatric solid tumors, with class I loss commonly associated with the transcriptional downregulation of HLA-B and transporter associated with antigen processing (TAP) genes, whereas class II antigen expression is scarce on tumor cells and occurs on immune infiltrating cells. Patients with tumors expressing sufficient HLA class I and TAP levels such as some glioma, osteosarcoma, Ewing sarcoma and non-rhabdomyosarcoma soft-tissue sarcoma cases may more likely benefit from T cell-based approaches, whereas strategies to upregulate HLA expression, to expand the immunopeptidome, and to target TAP-independent epitopes or possibly LOH might provide novel therapeutic opportunities in others. The consequences of HLA class II expression by immune cells remain to be established. Immunogenetic profiling should be implemented in routine to inform immunotherapy trials for precision medicine of pediatric cancers.

Abstract B049: Pancreatic beta cell stress pathways drive pancreatic ductal adenocarcinoma development in obesity

Abstract Epidemiologic studies have shown that obesity is a risk factor for more than a dozen cancers, including pancreatic ductal adenocarcinoma (PDAC). As PDAC is one of the leading causes of cancer-related death and obesity rates are rapidly increasing worldwide, it is imperative that we understand the mechanisms by which obesity promotes PDAC progression. To address this gap in knowledge, our lab combined a well-established genetic model for obesity (O: Lepob/ob) with a Kras-driven pancreatic cancer model (KC: Pdx1-Cre; KrasLSL-G12D/+) that mimics human PDAC progression. Resultant KCO mice had a drastic increase in tumor development compared to their lean counterparts, whereas induced weight loss intercepted tumor progression, showing that the tumor-promoting effects of obesity can be reversed. Bulk RNA sequencing of tumors from these mice revealed aberrantly increased expression of multiple peptide hormones expressed in insulin-producing beta (b) cells of pancreatic islets, including cholecystokinin (CCK) and amylin (Iapp). Strikingly, transgenic expression of CCK and Iapp in b-cells was sufficient to promote Kras-driven pancreatic tumorigenesis in non-obese mice. Single-cell RNA sequencing of b cells showed a trajectory of changes in gene expression with increasing obesity from wildtype to high-fat diet-fed to Lepob/ob mice. Further in silico analysis combining archetypal (AANet) with pseudotime (TrajectoryNet) methods demonstrated that b cells misexpressing hormones (CCK and Iapp) arose from a specific subtype of preexisting b cells, specifically virgin b cells, a rare, immature, regenerative population. Preliminary in vivo lineage tracing analyses in MIP-CreERT;LSL-TdTomato;Lepob/ob mice support these findings. Finally, we investigated the transcriptional networks that lead to aberrant CCK and Iapp expression in b cells. By combining Grainger causality analysis with known gene-gene relationships in the Transcriptional Regulatory Relationship Unraveled by Sentence-based Text mining (TRRUST) v2 database, we discovered a stress-induced mitogen-activated protein kinase (MAPK8)-cJun pathway that promotes pro-tumorigenic hormone expression in b cells. These combined experimental and computational methods nominate novel b cell targets to subvert the development of PDAC, an exocrine tumor. Citation Format: Cathy C. Garcia, Aarthi Venkat, Alex Tong, Sherry Agabiti, Lauren Lawres, Rebecca Cardone, Richard Kibbey, Smita Krishnaswamy, Mandar D Muzumdar. Pancreatic beta cell stress pathways drive pancreatic ductal adenocarcinoma development in obesity [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B049.

Abstract A023: Cytokine loss leads to decreased tumor differentiation and a more aggressive phenotype

Abstract Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers with a 5-year survival rate of only 11% and approximately half the patients present with distant metastasis at the time of diagnosis. PDAC is accompanied by pronounced alterations in stromal responses and immune surveillance programs, which are now recognized as some of the major drivers in PDAC tumor evolution. The role of immune modulators in driving aggressiveness of PDAC is poorly understood. We investigate how the loss of host-derived IL-12 and IL-23 in murine models of pancreatic cancer can lead to changes in changes in tumor morphology, cellular differentiation, and tumor immune microenvironment. In orthotopic tumors isolated from IL-12 and IL-23 knockout mice tumor morphology is altered and appears to be less differentiated. Noticeably, ductal area decreases in tumors from IL-23 and IL-12 knockout mice. Single cell RNA sequencing of tumors isolated from IL-12 and IL-23 knockout mice reveals a cluster of tumor cells with decreased gastric gene expression. Gastric genes such as TFF1, TFF2, MUC5AC, GKN1, and GKN2 have been implicated in pancreatic cancer development, progression, and tumor subtype. The classical pancreatic tumor subtype designation correlates with better differentiated pancreatic tumors as opposed to the more poorly differentiated tumors in the basal subtype. The classical expression signature is characterized by the expression of GATA6 and other epithelial cell terminal differentiation genes and includes several of these gastric genes. We hypothesize that loss of IL-12 and IL-23 leads to loss of tumor differentiation and to a more aggressive phenotype. Citation Format: Whitney J. Bell, Nancy Kren, Yan Wang, Jennifer Modliszewski, Yi Xu, Meijiang Guan, Kathleen DelGiorno, Jen Jen Yeh, Yuliya Pylayeva-Gupta. Cytokine loss leads to decreased tumor differentiation and a more aggressive phenotype [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr A023.

Hypoxia-activated prodrug and antiangiogenic therapies cooperatively treat pancreatic cancer but elicit immunosuppressive G-MDSC infiltration.

We previously showed that ablation of tumor hypoxia can sensitize tumors to immune checkpoint blockade (ICB). Here, we used a Kras+/G12D TP53+/R172H Pdx1-Cre-derived (KPC-derived) model of pancreatic adenocarcinoma to examine the tumor response and adaptive resistance mechanisms involved in response to 2 established methods of hypoxia-reducing therapy: the hypoxia-activated prodrug TH-302 and vascular endothelial growth factor receptor 2 (VEGFR-2) blockade. The combination of both modalities normalized tumor vasculature, increased DNA damage and cell death, and delayed tumor growth. In contrast with prior cancer models, the combination did not alleviate overall tissue hypoxia or sensitize these KPC tumors to ICB therapy despite qualitative improvements to the CD8+ T cell response. Bulk tumor RNA sequencing, flow cytometry, and adoptive myeloid cell transfer suggested that treated tumor cells increased their capacity to recruit granulocytic myeloid-derived suppressor cells (G-MDSCs) through CCL9 secretion. Blockade of the CCL9/CCR1 axis could limit G-MDSC migration, and depletion of Ly6G-positive cells could sensitize tumors to the combination of TH-302, anti-VEGFR-2, and ICB. Together, these data suggest that pancreatic tumors modulate G-MDSC migration as an adaptive response to vascular normalization and that these immunosuppressive myeloid cells act in a setting of persistent hypoxia to maintain adaptive immune resistance.

Proteomic and transcriptomic analyses identify apo-transcobalamin-II as a biomarker of overall survival in osteosarcoma.

The large-scale proteomic platform known as the SomaScan® assay is capable of simultaneously measuring thousands of proteins in patient specimens through next-generation aptamer-based multiplexed technology. While previous studies have utilized patient peripheral blood to suggest serum biomarkers of prognostic or diagnostic value in osteosarcoma (OSA), the most common primary pediatric bone cancer, they have ultimately been limited in the robustness of their analyses. We propose utilizing this aptamer-based technology to describe the systemic proteomic milieu in patients diagnosed with this disease. To determine novel biomarkers associated with overall survival in OSA, we deployed the SomaLogic SomaScan® 7k assay to investigate the plasma proteomic profile of naive primary, recurrent, and metastatic OSA patients. Following identification of differentially expressed proteins (DEPs) between 2-year deceased and survivor cohorts, publicly available databases including Survival Genie, TIGER, and KM Plotter Immunotherapy, among others, were utilized to investigate the significance of our proteomic findings. Apo-transcobalamin-II (APO-TCN2) was identified as the most DEP between 2-year deceased and survivor cohorts (Log2 fold change = 6.8, P-value= 0.0017). Survival analysis using the Survival Genie web-based platform indicated that increased intratumoral TCN2 expression was associated with better overall survival in both OSA (TARGET-OS) and sarcoma (TCGA-SARC) datasets. Cell-cell communication analysis using the TIGER database suggested that TCN2+ Myeloid cells likely interact with marginal zone and immunoglobin-producing B lymphocytes expressing the TCN2 receptor (CD320) to promote their proliferation and survival in both non-small cell lung cancer and melanoma tumors. Analysis of publicly available OSA scRNA-sequencing datasets identified similar populations in naive primary tumors. Furthermore, circulating APO-TCN2 levels in OSA were then associated with a plasma proteomic profile likely necessary for robust B lymphocyte proliferation, infiltration, and formation of intratumoral tertiary lymphoid structures for improved anti-tumor immunity. Overall, APO-TCN2, a circulatory protein previously described in various lymphoproliferative disorders, was associated with 2-year survival status in patients diagnosed with OSA. The relevance of this protein and apparent immunological function (anti-tumor B lymphocyte responses) was suggested using publicly available solid tumor RNA-sequencing datasets. Further studies characterizing the biological function of APO-TCN2 and its relevance in these diseases is warranted.