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Gastroesophageal adenocarcinoma (GEA) is the fastest rising cancer in North America. Over the course of five years, the survival rate is 200 GEA patients. A single-cell RNA sequencing atlas developed from >30 GEA DCF- or FLOT-treated patient samples will be used to identify CAF markers and targetable processes. CAF sub-populations will then be elucidated and correlated to tumor response. IF, FACS, and ELISA will be performed for subsequent CAF marker validation and characterization. Ex vivo drug testing with DCF or FLOT will be conducted on PDO-CAF co-cultures to recapitulate their drug response. Citation Format: Kulsum Tai, Sanjima Pal, Julie Bérubé, Iris Kong, Adam Hoffman, Swneke Bailey, Aki Kirbizakis, Sui Huang, Michael Strasser, David Gibbs, Nicholas Bertos, Veena Sangwan, Lorenzo Ferri. Dissecting the stromal drivers of gastroesophageal adenocarcinoma chemoresistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5959.

Metastasis is responsible for 90% of all cancer-related deaths, making it the most significant challenge in cancer treatment for clinicians worldwide. Metastasis is thought to occur in a stepwise process, in which local lymph nodes (LNs) are first colonized by tumour cells before proceeding to distal organs. However, the mechanism by which LN metastasis facilitates distal metastasis is poorly understood. LNs undergo environmental changes to accommodate tumour cell growth within, notably by shifting the environment towards immunosuppression to shut down anti-tumour immune cells. This immunosuppressive environment is critical for the establishment of LN metastases, as cytotoxic CD8 T cells will otherwise neutralize incoming circulating tumour cells. Neutrophils are among the first cells recruited to tumour-draining LNs to mediate the environmental shift, and yet their method of action has not been fully elucidated. They have recently been found to secrete NETs within LNs during cancer, which are pro-inflammatory web-like formations of DNA decorated with antimicrobial peptides. While NETs have been shown to exert pro-tumour effects in the tumour microenvironment and to facilitate metastasis as a whole, their role in LNs has never been explored. Using a NETs deficient mouse model (PAD4-/-), we report that NETs deposition within the tumour-draining LNs of mice upregulates the Treg population while simultaneously downregulating anti-tumour CD8 T cell proliferation and activation. Following these findings, we performed an in vitro suppression assay and found that NETs-educated Tregs hinder the expansion of CD8 T cells more than non-NETs-educated Tregs. Finally, through an induced metastasis mouse model, we have observed that tumour-draining LN resection as well as the absence of NETs protects against the development of distal metastasis, and decreases body-wide inflammation as seen by a lowered Neutrophil-to-Lymphocyte ratio in the circulation. Taken together, these findings highlight the role of NETs deposition in LNs as a key player in disease progression and bring forward a potential target for anti-metastatic drug development. Citation Format: Ariane Brassard, Xin Su, Iqraa Dhoparee-Doomah, Sabrina Leo, Lixuan Feng, France Bourdeau, Betty Giannias, Corissa Larson, Qian Qiu, Jonathan Spicer, Lorenzo Ferri, Jonathan Cools-Lartigue. NETs act as immunosuppressive agents within lymph nodes during cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1315.

Introduction: Esophageal cancer causes sixth most cancer-related morbidity and mortality worldwide, with a survival rate of 60%) in North America. Systemic docetaxel-based triplet chemotherapy represents the best standard of care, approx. 60% of patients showcasing innate chemo-resistance or developing acquired chemo-resistance. 3D organoids provide a robust and heterogeneous cell source but lack the stromal microenvironment. We established a high-fidelity, stromal-inclusive tumor-on-chip platform expanding on tumor heterogeneity with micro-physiological relevance and flexible complexity. Methods: A total of 8 (4 chemo-sensitive and 4 chemo-resistant) treatment naïve patient-derived organoids (PDOs) and matched fibroblasts were selected to develop syngeneic human esophageal microtissues (tumor and adjacent) on commercially available (Emulate), compartmentalized, porous polydimethylsiloxane (PDMS) membrane-based microfluidic device. Chips accommodate organoids-derived epithelial cells at the upper mucosal channel and matched fibroblasts at the bottom stromal channel. 3D-microtissue development on the chip and treatment-induced cytotoxicity were examined for up to 11 days. We followed the FLOT (docetaxel, oxaliplatin, and 5-fluorouracil; 1:1.7:52) based chemotherapy regime on the chip and evaluated the recapitulation of patient-specific response. Epithelial barrier integrity, adenocarcinoma-associated cellular proteins, and level of cyfra 21-1 (circulating tumor biomarker) were determined on-chip grown microtissues. Results: Real-time brightfield microscopic observations revealed that the EA chips manifest mucin production, adequate tissue tight epithelial barriers, and distinct morphological characteristics that emerged with adenocarcinoma progression. Presence of pleomorphic cells (multiple shapes and sizes), establishment of tight epithelial barriers and formation of mature microvilli was observed via electron microscopy. Patient specific tumor tissue growth were observed for maximum 12 days under a physiologically relevant media flow. Perfusion of pharmacokinetically pertinent doses of triplet chemotherapeutic compounds performed through the stromal channel and each chip recapitulated level of chemosensitivity observed in the patient. Fluorescent probes and LDH assay also demonstrated patient-specific chemo response. Confocal imaging revealed differential expression of proliferation (ki67), epithelial (CK7, E-cadherin), and mesenchymal (Vimentin) markers in each patient-derived chip. Conclusions: Human esophageal adenocarcinoma-on-a-chip is a novel, most human-relevant biomimetic platform built on a microfluidic chip and a potential alternative to inadequate pre-clinical animal models in the future. Citation Format: Sanjima Pal, Elee Shimshoni, Salvador Flores-Torres, Julie Bérubé, Kulsum Tai, Iris Kong, Betty Giannias, Sean Hall, Nicholas Bertos, Veena Sangwan, Donald E. Ingber, Lorenzo Ferri. Esophageal adenocarcinoma-on-a-chip; modeling patient specific disease progression and a step towards functional precision oncology [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 168.

Introduction: Gastroesophageal adenocarcinoma (GEA) is one of the most lethal malignancies worldwide. Even with the standard-of-care chemotherapy, 40% of the patients are innately resistant and half of the initial responders develop acquired resistance. The molecular mechanisms underlying the development of resistance in GEA remain largely unknown. Methods: 30 GEA patients who received chemotherapy were included in this cohort. Both pre-and post-treatment primary tissues were collected to generate patient-derived organoids (PDOs). 29 PDOs were treated with chemotherapeutic agents and the cell viability was measured. We also evaluated the correlation between ex-vivo drug responses of PDOs and in-patient clinical responses. Data obtained from whole-exome (WES) and RNA sequencing of the primary tumor and their PDOs were analyzed to identify targetable molecules associated with chemo-resistance. Results: After treatment, the cell viability of the PDOs obtained from chemo-resistant patients was significantly higher than that of chemo-sensitive patients. The variant allele frequency of the PDOs recapitulated their parental tumors. WES of one patient tumor revealed an increased copy number of EGFR, and their PDOs showed high sensitivity to an EGFR inhibitor in the subsequent drug screens. Furthermore, 40% of chemo-sensitive patients had mutations in one or more genes belonging to the adhesion G protein-coupled receptors (GPCRs) family. The adenylate cyclase-activating G protein-coupled receptor signaling pathway was found to be significantly activated only in chemo-sensitive patients. Single-cell RNA sequencing of pre-and post-treatment tissue revealed a broadly shifted transcriptome in epithelial cells. Patients with upregulated cell stemness genes including CTNNB1, MYC, ETS2, and KLF4 had disease recurrence 6 months post-surgery, while patients with unaltered or downregulated stemness genes remain disease-free 18 months until today. Conclusion: Our PDOs not only reflected the genetic profile of primary tumors but also recapitulated patient responses to chemotherapy. Genomic analysis revealed that mutations in a few GPCR genes might have a role in increased sensitivity to chemotherapy. In addition, the transcriptomic analysis showed stemness genes were associated with disease recurrence. Our GEA PDO platform allows the identification and the subsequent verification of resistant-conferring targets, providing insight for novel therapeutic combinations. Funding: This project is supported by the Cancer Research Society (CCS), and the Department of Defence (DoD), USA. Citation Format: Mingyang Kong, Swneke Bailey, Veena Sangwan, Lorenzo Ferri. Identify targetable molecular drivers of chemotherapy resistance in gastroesophageal adenocarcinoma [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 3068.

Introduction: Esophagogastric adenocarcinomas with microsatellite instability (MSI) high status often display chemoresistance, as the current therapies are ineffective. It is hypothesized that the poor response of MSI-high esophagogastric adenocarcinomas to therapies is due to the extensive genomic mutational heterogeneity, which can be overcome by identifying, stratifying, and targeting multiple genetic alterations concurrently. The goals of this project are to: 1) Identify a matched retrospective cohort of 20 MSI-high to 20 microsatellite stable organoids, derived from biobanked tumor tissue. 2) Analyze mismatch repair protein function/loss, to confirm that the primary tumor microsatellite status is recapitulated in 3D organoid models. 3) Test standard of care chemotherapies, and explore alternative approaches to prevent chemoresistance by evaluating targeted agents based on genomic sequencing. Methods: Patient-derived organoids grow for ~14 days, after which they are enzymatically disrupted and plated in Matrigel. I will confirm that the organoid models accurately represent clinal response, by treating them with the same chemotherapy received by the patient. 10 different drug concentrations are added in triplicate using a drug dispenser, then after 72 hours, organoid viability is determined with a plate reader. Results: Genomic characterization of 13/226 MSI-high cases has been conducted with a 234 gene gastric cancer specific panel to identify and target genomic alterations. Preliminary robotic drug screens guided by these mutation profiles have been conducted, yielding promising alternative treatments. Conclusions: By targeting the particular mutations found in MSI-high patients, it could help explain the chemoresistance mechanism, so promising personalized treatment approaches for esophagogastric adenocarcinomas can be clinically implemented. Sources of Funding: This project is funded by the Inez and Willena Beaton Award in Oncology, valued at $7,500 and provided by the RI-MUHC. The operating grants that support the research are $120,000 over 2 years from the Cancer Research Society, and $1,200,000 USD over 3 years given by the Department of Defense. Citation Format: Adam Hoffman, Sanjima Pal, Veena Sangwan, Lorenzo Ferri. Personalized chemotherapy treatments for microsatellite instable tumors [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 2625.

Low density (LDNs) and high density (HDNs) are two neutrophil subsets that can be separated through gradient centrifugation. LDNs was shown to be a tumor-promoting phenotype and high percentage of circulating LDNs was associated with poor cancer prognosis. In the last decade, it has also been suggested that neutrophil-to-lymphocyte ratio (NLR) is a marker of cancer-associated inflammation and high peripheral blood NLR was associated with poor cancer patient survival. Our study therefore aimed to i) establish the correlation between the percentage of circulating LDN fraction and blood NLR in cancer patients; ii) determine the differences between LDN and HDN protein expression; iii) compare the protein expression of neutrophils between cancer patients and healthy volunteers. Materials & methods: Peripheral blood of esophageal/gastric cancer patients with clinical stage of II-III were collected. Circulating LDNs and HDNs were isolated using differential density centrifugation, and protein expression determined by immunophenotyping of cells using 12 different markers. Immunophenotyping of neutrophils from healthy volunteers was compared with that of cancer patients using the same panel of markers. Results: The percentage of circulating LDN fraction varied between 0.2% to 40% in cancer patients with an average higher than that in healthy volunteers. LDN fraction was significantly elevated in patients with high peripheral blood NLR (NLR above 4). We observed a positive Pearson's correlation between NLR and LDN fraction in blood of cancer patients. Compared to HDNs, pro-tumor LDNs was bigger in size and exhibited a higher expression of Arginase 1 (Arg1), CD66b (CEACA-8), and CXCR2. Peripheral blood neutrophils (PBNs) in cancer patients, containing both HDN and LDN fractions, showed a lower expression of Arg1 and neutrophil elastase (NE). Conclusion: Higher percentage of circulating LDNs in patients with elevated blood NLR may explain the correlation between high NLR and poor survival in cancer patients. High Arg1 expression of LDNs compared to HDNs can contribute to LDNs pro-tumor activity. Decreased expression of Arg1 and NE in PBNs of cancer patients compared to healthy subjects could be due to the degranulation of PBNs in cancer patients. Citation Format: Ramin Rohanizadeh, Olivia Koufos, Xin Su, Ariane Brassard, Betty Giannias, France Bourdeau, Roni Rayes, Jonathan Spicer, Veena Sangwan, Swneke Bailey, Lorenzo Ferri, Jonathan Cools-Lartigue. Peripheral blood neutrophil-to-lymphocyte ratio (NLR), a predictor of poor survival in cancer patients, was positively associated with the percentage of circulating low-density neutrophil fraction [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 1767.

Adenocarcinoma of the proximal stomach is the fastest rising malignancy in North America, and is associated with a high rate of recurrence to the peritoneum. As part of cancer treatment, the majority of patients undergo at least one invasive surgical procedure. Recent clinical data has linked postoperative infection complications with adverse oncologic outcomes; however, the underlying mechanisms are unclear. Emerging evidence suggests that the release of TNFa, a key inflammatory cytokine during infection facilitates cancer progression. The role and mechanisms the gram-negative bacterial infections play in facilitating the metastatic potential of gastric cancer to the peritoneum is entirely unknown. We hypothesized that incubation of gastric cancer cells and MC with heat-inactivated E. Coli or LPS can augment gastric cancer cell adhesion and invasion via TNFR1 signaling and increase the potential of peritoneal metastasis. Incubation of human gastric cancer cells or/and MC with heat inactivated E. coli, LPS or TNFa significantly increased in vitro adhesion 3-4 folds to MC and enhanced in vitro invasion. These enhanced cell adhesion and invasion phenotypes following incubation with LPS or E. coli were attenuated at three levels: inhibition of TLR4 (Eritoran), inhibition of TNFR1 (anti-TNFR1/isotype control antibodies) or p38 MAPK inhibitor (BIRB0796). TNFa treatment also increases CD54, CD44 and CD29 expression on cancer cells and MC. To further validate in vitro results, a novel ex-vivo murine peritoneal metastasis model is developed. We report that ex vivo gastric cancer cells adhesion to murine peritoneum is augmented by overnight LPS, E. Coli and TNFa treatments and this effect was abrogated when TNFR1-/- mouse peritoneum is used or in the presence of TNFR1 monoclonal or isotype control antibodies. These findings implicate TNFa in the process of gastric cancer metastasis to peritoneum in the context of systemic infection and identify TNFa as potential therapeutic targets. Citation Format: Malak Alzahrani, Betty Giannias, France Bourdeau, Rafael Kayano, Lorenzo Ferri. Gram-negative bacterial infection enhances the potential of gastric adenocarcinoma peritoneal metastasis via TNFR1 dependent manner. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Metastasis; 2015 Nov 30-Dec 3; Austin, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(7 Suppl):Abstract nr A29.