GIST Quiz: TesNt your knowledge.

Having a strong understanding of the epidemiology, pathophysiology, and clinical management of Gastrointestinal Stromal Tumors (GIST) is critical for clinicians who may encounter this cancer. The quiz below is designed for medical students, residents, fellows, and practicing physicians to test their knowledge and review key concepts for understanding GIST.

Cyclin-Dependent Kinase 4/6 Inhibition as a Novel Therapy for Peritoneal Mucinous Carcinomatosis With GNAS Mutations.

PURPOSE: Mucinous neoplasms of the gastrointestinal tract are characterized by a propensity for metastasis to the peritoneum, resulting in peritoneal mucinous carcinomatosis (PMC). A subset of these tumors, most often originating in the appendix, harbor mutations in the GNAS oncogene. While the natural history of GNAS-mutant PMC varies, patient outcomes are generally poor, as is response to cytotoxic chemotherapy. The purpose of this study was to evaluate the clinical efficacy of single-agent palbociclib, a cyclin-dependent kinase (CDK)4/6 inhibitor, in patients with GNAS-mutant PMC. PATIENTS AND METHODS: We enrolled 16 patients with PMC in a single-arm personalized cancer therapy trial. For all patients, tumor tissue and/or circulating tumor DNA genomic profiling using next-generation sequencing and, when possible, PD-L1 expression, tumor mutational burden, and microsatellite instability status was assessed. Twelve of 16 patients had previous disease progression on at least one previous line of chemotherapy. The primary tumor was appendix in 13 patients, unknown in two patients, and pancreas in one patient. Eleven cases were classified as low grade, and five as high grade. RESULTS: In 13 of 16 patients, we observed a decrease in carcinoembryonic antigen (CEA), and in six patients, the CEA declined by >50%. As measured by clinical and modified peritoneal RECIST criteria, 50% of evaluable patients had stable disease after 12 months of palbociclib. At a median follow-up of 17.6 months, median survival has not been reached. Clinical response to CDK4/6 inhibition was mirrored in tumors with GNAS mutation and mucinous histology using an ex vivo preclinical platform. CONCLUSION: CDK4/6 inhibition with palbociclib had clinical activity in PMC characterized by mutations in GNAS that was superior to that previously reported with cytotoxic chemotherapy. CDK4/6 inhibition is a novel therapeutic strategy worthy of further evaluation in this subgroup of gastrointestinal neoplasms.

Accurate Co-Localization of Luciferase Expression and Fluorescent Anti-CEA Antibody Targeting of Liver Metastases in an Orthotopic Mouse Model of Colon Cancer.

BACKGROUND: The present study aimed to validate the accuracy of a tumor-specific antibody to target liver metastases of colorectal cancer. METHODS: A humanized anti-CEA antibody conjugated to a fluorescent dye (M5A-IR800) was tested for targeting human colorectal cancer liver metastases (CRLMs) expressing luciferase in an orthotopic mouse model. Orthotopic mouse models of CRLMs were established by implanting fragments of a luciferase-expressing human colorectal cancer cell line, LS174T, in the liver of nude mice. Mice received 50 µg M5A-IR800 72 h prior to imaging. To test co-localization, bioluminescence imaging was performed using D-luciferin, which was given via intraperitoneal injection just prior to imaging. RESULTS: Tumors were able to be visualized non-invasively through the skin with the luciferase-luciferin signal. Intra-abdominal imaging showed accurate labeling of CRLMs with M5A-IR800, which co-localized with the luciferase-luciferin signal. CONCLUSIONS: The present results validate the accuracy of a tumor-specific anti-CEA antibody in targeting liver metastases of colorectal cancer.

HIF-2α drives hepatic Kupffer cell death and proinflammatory recruited macrophage activation in nonalcoholic steatohepatitis.

Proinflammatory hepatic macrophage activation plays a key role in the development of nonalcoholic steatohepatitis (NASH). This involves increased embryonic hepatic Kupffer cell (KC) death, facilitating the replacement of KCs with bone marrow-derived recruited hepatic macrophages (RHMs) that highly express proinflammatory genes. Moreover, phago/efferocytic activity of KCs is diminished in NASH, enhancing liver inflammation. However, the molecular mechanisms underlying these changes in KCs are not known. Here, we show that hypoxia-inducible factor 2α (HIF-2α) mediates NASH-associated decreased KC growth and efferocytosis by enhancing lysosomal stress. At the molecular level, HIF-2α stimulated mammalian target of rapamycin (mTOR)- and extracellular signal-regulated kinase-dependent inhibitory transcription factor EB (TFEB) phosphorylation, leading to decreased lysosomal and phagocytic gene expression. With increased metabolic stress and phago/efferocytic burden in NASH, these changes were sufficient to increase lysosomal stress, causing decreased efferocytosis and lysosomal cell death. Of interest, HIF-2α-dependent TFEB regulation only occurred in KCs but not RHMs. Instead, in RHMs, HIF-2α promoted mitochondrial reactive oxygen species production and proinflammatory activation by increasing ANT2 expression and mitochondrial permeability transition. Consequently, myeloid lineage-specific or KC-specific HIF-2α depletion or the inhibition of mTOR-dependent TFEB inhibition using antisense oligonucleotide treatment protected against the development of NASH in mice. Moreover, treatment with an HIF-2α-specific inhibitor reduced inflammatory and fibrogenic gene expression in human liver spheroids cultured under a NASH-like condition. Together, our results suggest that macrophage subtype-specific effects of HIF-2α collectively contribute to the proinflammatory activation of liver macrophages, leading to the development of NASH.

IL-22 resolves MASLD via enterocyte STAT3 restoration of diet-perturbed intestinal homeostasis.

The exponential rise in metabolic dysfunction-associated steatotic liver disease (MASLD) parallels the ever-increasing consumption of energy-dense diets, underscoring the need for effective MASLD-resolving drugs. MASLD pathogenesis is linked to obesity, diabetes, "gut-liver axis" alterations, and defective interleukin-22 (IL-22) signaling. Although barrier-protective IL-22 blunts diet-induced metabolic alterations, inhibits lipid intake, and reverses microbial dysbiosis, obesogenic diets rapidly suppress its production by small intestine-localized innate lymphocytes. This results in STAT3 inhibition in intestinal epithelial cells (IECs) and expansion of the absorptive enterocyte compartment. These MASLD-sustaining aberrations were reversed by administration of recombinant IL-22, which resolved hepatosteatosis, inflammation, fibrosis, and insulin resistance. Exogenous IL-22 exerted its therapeutic effects through its IEC receptor, rather than hepatocytes, activating STAT3 and inhibiting WNT-ß-catenin signaling to shrink the absorptive enterocyte compartment. By reversing diet-reinforced macronutrient absorption, the main source of liver lipids, IL-22 signaling restoration represents a potentially effective interception of dietary obesity and MASLD.

Goblet cell adenocarcinoma.

Appendix, considered a vestigial and disposable organ, has been long neglected as a source of abdominal tumors. Among the appendiceal tumors, goblet cell adenocarcinoma (GCA) is a rare primary epithelial neoplasm which has undergone multiple name changes and classifications in recent years, adding to confusion surrounding this unique amphicrine tumor. This entity was previously known as goblet cell carcinoid and adenocarcinoma ex goblet cell carcinoid. This review article provides an update on pathology, nomenclature, and recent classification systems with emphasis on 2019 World Health Organization Classification of Tumors, 3-tiered grading system.1.

Targeting Patient-Derived Orthotopic Gastric Cancers with a Fluorescent Humanized Anti-CEA Antibody.

BACKGROUND: Gastric cancer poses a major diagnostic and therapeutic challenge as surgical resection provides the only opportunity for a cure. Specific labeling of gastric cancer could distinguish resectable and nonresectable disease and facilitate an R0 resection, which could improve survival. METHODS: Two patient-derived gastric cancer lines, KG8 and KG10, were established from surgical specimens of two patients who underwent gastrectomy for gastric adenocarcinoma. Harvested tumor fragments were implanted into the greater curvature of the stomach to establish patient-derived orthotopic xenograft (PDOX) models. M5A (humanized anti-CEA antibody) or IgG control antibodies were conjugated with the near-infrared dye IRDye800CW. Mice received 50 µg of M5A-IR800 or 50 µg of IgG-IR800 intravenously and were imaged after 72 hr. Fluorescence imaging was performed by using the LI-COR Pearl Imaging System. A tumor-to-background ratio (TBR) was calculated by dividing the mean fluorescence intensity of the tumor versus adjacent stomach tissue. RESULTS: M5A-IR800 administration resulted in bright labeling of both KG8 and K10 tumors. In the KG8 PDOX models, the TBR for M5A-IR800 was 5.85 (SE ± 1.64) compared with IgG-IR800 at 0.70 (SE ± 0.17). The K10 PDOX models had a TBR of 3.71 (SE ± 0.73) for M5A-IR800 compared with 0.66 (SE ± 0.12) for IgG-IR800. CONCLUSIONS: Humanized anti-CEA (M5A) antibodies conjugated to fluorescent dyes provide bright and specific labeling of gastric cancer PDOX models. This tumor-specific fluorescent antibody is a promising potential clinical tool to detect the extent of disease for the determination of resectability as well as to visualize tumor margins during gastric cancer resection.

Distinguishing characteristics of xanthogranulomatous cholecystitis and gallbladder adenocarcinoma: a persistent diagnostic dilemma.

BACKGROUND: Xanthogranulomatous cholecystitis (XGC) is an uncommon variant of chronic cholecystitis which can resemble gallbladder adenocarcinoma (GAC) on preoperative imaging and present technical challenges in the performance of cholecystectomy. We examined our experience with each pathology to identify distinguishing characteristics that may guide patient counseling and surgical management. METHODS: A retrospective review of all pathologically confirmed cases of XGC and GAC following cholecystectomy between 2015 and 2021 at a single institution was performed. Clinical, biochemical, radiographic, and intraoperative features were compared. RESULTS: There were 37 cases of XGC and 20 cases of GAC. Patients with GAC were older (mean 70.3 years vs 58.0, p = 0.01) and exclusively female (100% vs 45.9%, p < 0.0001). There were no significant differences in accompanying symptoms between groups (nausea/vomiting, fevers, or jaundice). The mean maximum white blood cell count was elevated for XGC compared to GAC (16.4 vs 8.6 respectively, p = 0.044); however, there were no differences in the remainder of the biochemical profile, including bilirubin, liver transaminases, CEA, and CA 19-9. The presence of an intraluminal mass (61.1% vs 9.1%, p = 0.0001) and lymphadenopathy (18.8%. vs 0.0%, p = 0.045) were associated with malignancy, whereas gallbladder wall thickening as reported on imaging (87.9% vs 38.9%, p = 0.0008) and gallstones (76.5% vs. 50.0%, p = 0.053) were more often present with XGC. Cases of XGC more often had significant adhesions/inflammation (83.8% vs 55.0%, p = 0.03). CONCLUSION: Clinical features that may favor benign chronic cholecystitis over gallbladder adenocarcinoma include younger age, male gender, current or prior leukocytosis, and the absence of an intraluminal mass or lymphadenopathy. Laparoscopic cholecystectomy is a safe surgical option for equivocal presentations. Intraoperative frozen section or intentional staging of more extensive procedures based upon final histopathology are valuable surgical strategies.

Humanized Anti-Carcinoembryonic Antigen Antibodies Brightly Target and Label Gastric Cancer in Orthotopic Mouse Models.

INTRODUCTION: Gastric cancer poses a major therapeutic challenge. Improved visualization of tumor margins at the time of gastrectomy with fluorescent tumor-specific antibodies could improve outcomes. The present report demonstrates the potential of targeting gastric cancer with a humanized anti-carcinoembryonic antigen (CEA) antibody in orthotopic mouse models. METHODS: MKN45 cells were injected subcutaneously into nude mice to establish xenograft models. Tumor fragments collected from subcutaneous models were then implanted into the greater curvature of the stomach to establish orthotopic models. For tumor labeling, a humanized anti-CEA antibody (M5A) and IgG as a control, were conjugated with the near-infrared dye IRDye800CW. Time (24-72 h) and dose (50-100 µg) response curves were performed in subcutaneous models. Orthotopic models received 50 µg of M5A-IR800 or 50 µg IgG-IR800 as a control and were imaged after 72 h. Fluorescence imaging was performed on the mice using the LI-COR Pearl Imaging System. RESULTS: In subcutaneous models, tumor to background ratios (TBRs) reached 8.85 at 72 h. Median TBRs of orthotopic model primary tumors were 6.25 (interquartile range [IQR] 6.03-7.12) for M5A-IR800 compared to 0.42 (IQR 0.38-0.54) for control. Abdominal wall metastasis median TBRs were 13.52 (IQR 12.79-13.76) for M5A-IR800 and 3.19 (IQR 2.65-3.73) for the control. Immunohistochemistry confirmed CEA expression within tumors. CONCLUSIONS: Humanized anti-CEA antibodies conjugated to near-infrared dyes provide specific labeling of gastric cancers in mouse models. Orthotopic models demonstrated bright and specific labeling with TBRs greater than ten times that of control. This tumor-specific fluorescent antibody is a promising potential clinical tool for improving visualization of gastric cancer margins at time of surgical resection.

Discrimination of cell-intrinsic and environment-dependent effects of natural genetic variation on Kupffer cell epigenomes and transcriptomes.

Noncoding genetic variation drives phenotypic diversity, but underlying mechanisms and affected cell types are incompletely understood. Here, investigation of effects of natural genetic variation on the epigenomes and transcriptomes of Kupffer cells derived from inbred mouse strains identified strain-specific environmental factors influencing Kupffer cell phenotypes, including leptin signaling in Kupffer cells from a steatohepatitis-resistant strain. Cell-autonomous and non-cell-autonomous effects of genetic variation were resolved by analysis of F1 hybrid mice and cells engrafted into an immunodeficient host. During homeostasis, non-cell-autonomous trans effects of genetic variation dominated control of Kupffer cells, while strain-specific responses to acute lipopolysaccharide injection were dominated by actions of cis-acting effects modifying response elements for lineage-determining and signal-dependent transcription factors. These findings demonstrate that epigenetic landscapes report on trans effects of genetic variation and serve as a resource for deeper analyses into genetic control of transcription in Kupffer cells and macrophages in vitro.

PEGylated Fluorescent Anti-carcinoembryonic Antigen Antibody Labels Colorectal Cancer Tumors in Orthotopic Mouse Models.

INTRODUCTION: Colorectal cancer (CRC) patients often develop liver metastasis. However, curative resection of liver metastasis is not always possible due to poor visualization of tumor margins. The present study reports the characterization of a humanized anti-carcinoembryonic antigen monoclonal antibody conjugated to a PEGylated near-infrared dye, that targets and brightly labels human CRC tumors in metastatic orthotopic mouse models. METHODS: The hT84.66-M5A (M5A) monoclonal antibody was conjugated with a polyethylene glycol (PEG) chain that incorporated a near infrared (NIR) IR800 dye to establish M5A-IR800 Sidewinder (M5A-IR800-SW). Nude mice with CRC orthotopic primary tumors and liver metastasis both developed from a human CRC cell line, were injected with M5A-IR800-SW and imaged with the Pearl Trilogy Imaging System. RESULTS: M5A-IR800-SW targeted and brightly labeled CRC tumors, both in primary-tumor and liver-metastasis models. M5A-IR800-SW at 75 µg exhibited highly-specific tumor labeling in a primary-tumor orthotopic model with a median tumor-to-background ratio of 9.77 and in a liver-metastasis orthotopic model with a median tumor-to-background ratio of 7.23 at 96 h. The precise labeling of the liver metastasis was due to lack of hepatic accumulation of M5A-IR800-SW in the liver. CONCLUSIONS: M5A-IR800-SW provided bright and targeted NIR images of human CRC in orthotopic primary-tumor and liver-metastasis mouse models. The results of the present study suggest the clinical potential of M5A-IR800-SW for fluorescence-guided surgery including metastasectomies for CRC. The lack of hepatic NIR signal is of critical importance to allow for precise labeling of liver tumors.

Isolation of primary human liver cells from normal and nonalcoholic steatohepatitis livers.

Here, we present a protocol for isolating human hepatocytes and neural progenitor cells from normal and nonalcoholic steatohepatitis livers. We describe steps for perfusion for scaled-up liver cell isolation and optimization of chemical digestion to achieve maximal yield and cell viability. We then detail a liver cell cryopreservation and potential applications, such as the use of human liver cells as a tool to link experimental and translational research.

Specific Targeting and Labeling of Colonic Polyps in CPC-APC Mice with Mucin 5AC Fluorescent Antibodies: A Model for Detection of Early Colon Cancer.

Poor visualization of polyps can limit colorectal cancer screening. Fluorescent antibodies to mucin5AC (MUC5AC), a glycoprotein upregulated in adenomas and colorectal cancer, could improve screening colonoscopy polyp detection rate. Adenomatous polyposis coli flox mice with a Cdx2-Cre transgene (CPC-APC) develop colonic polyps that contain both dysplastic and malignant tissue. Mice received MUC5AC-IR800 or IRdye800 as a control IV and were sacrificed after 48 h for near-infrared imaging of their colons. A polyp-to-background ratio (PBR) was calculated for each polyp by dividing the mean fluorescence intensity of the polyp by the mean fluorescence intensity of the background tissue. The mean 25 µg PBR was 1.70 (±0.56); the mean 50 µg PBR was 2.64 (±0.97); the mean 100 µg PBR was 3.32 (±1.33); and the mean 150 µg PBR was 3.38 (±0.87). The mean PBR of the dye-only control was 2.22 (±1.02), significantly less than the 150 µg arm (p-value 0.008). The present study demonstrates the ability of fluorescent anti-MUC5AC antibodies to specifically target and label colonic polyps containing high-grade dysplasia and intramucosal adenocarcinoma in CPC-APC mice. This technology can potentially improve the detection rate and decrease the miss rate of advanced colonic neoplasia and early cancer at colonoscopy.

Highly Selective Targeting of Pancreatic Cancer in the Liver with a Near-Infrared Anti-MUC5AC Probe in a PDOX Mouse Model: A Proof-of-Concept Study.

Accurately identifying metastatic disease is critical to directing the appropriate treatment in pancreatic cancer. Mucin 5AC is overexpressed in pancreatic cancer but absent in normal pancreas tissue. The present proof-of-concept study demonstrates the efficacy of an anti-mucin 5AC antibody conjugated to an IR800 dye (MUC5AC-IR800) to preferentially label a liver metastasis of pancreatic cancer (Panc Met) in a unique patient-derived orthotopic xenograft (PDOX) model. In orthotopic models, the mean tumor to background ratio was 1.787 (SD ± 0.336), and immunohistochemistry confirmed the expression of MUC5AC within tumor cells. MUC5AC-IR800 provides distinct visualization of pancreatic cancer liver metastasis in a PDOX mouse model, demonstrating its potential utility in staging laparoscopy and fluorescence-guided surgery.

Imaging Non-alcoholic Fatty Liver Disease Model Using H-1 and F-19 MRI.

PURPOSE: We explore the use of intravenously delivered perfluorocarbon (PFC) nanoemulsion and 19F MRI for detecting inflammation in a mouse model of non-alcoholic fatty liver disease (NAFLD). Correlative studies of 1H-based liver proton density fat fraction (PDFF) and T1 measurements and histology are also evaluated. PROCEDURES: C57BL/6 mice were fed standard or high-fat diet (HFD) for 6 weeks to induce NAFLD. 1H MRI measurements of PDFF and T1 relaxation time were performed at baseline to assess NAFLD onset prior to administration of a PFC nanoemulsion to enable 19F MRI of liver PFC uptake. 1H and 19F MRI biomarkers were acquired at 2, 21, and 42 days post-PFC to assess changes. Histopathology of liver tissue was performed at experimental endpoint. RESULTS: Significant increases in liver volume, PDFF, and total PFC uptake were noted in HFD mice compared to Std diet mice. Liver fluorine density and T1 relaxation time were significantly reduced in HFD mice. CONCLUSIONS: We demonstrated longitudinal quantification of multiple MRI biomarkers of disease in NAFLD mice. The changes in liver PFC uptake in HFD mice were compared with healthy mice that suggests that 19F MRI may be a viable biomarker of liver pathology.

Is Routine Omentectomy a Necessary Component of Cytoreductive Surgery and HIPEC?

BACKGROUND: Cytoreductive surgery (CRS) with or without hyperthermic intraperitoneal chemotherapy (HIPEC) for peritoneal metastases traditionally includes omentectomy, even in the absence of visible omental metastases. We sought to determine the rate of occult histologic omental metastasis (OHOM), evaluate morbidity with omentectomy, and examine the rate of omental recurrence among patients undergoing CRS-HIPEC. METHODS: All CRS-HIPEC procedures from August 2007 to August 2020 were included in this single-center, retrospective, cohort study. Procedures were divided into those that included greater omentectomy (OM) and those that did not (NOM). The incidence of OHOM was evaluated specifically among the OM group with a grossly normal omentum. Multivariate regression analyses were performed to evaluate return of bowel function, ileus, and morbidity in the OM and NOM groups. RESULTS: Among 683 CRS-HIPEC procedures, 578 (84.6%) included omentectomy and 105 (15.4%) did not. The OM group had higher operative time, blood loss, peritoneal cancer index, number of visceral resections, and length of stay. In the OM group, 72 (12.5%) patients had a grossly normal omentum, and 23 (31.9%) of these had OHOM. Risk-adjusted return of bowel function, ileus, and 60-day complications were no different in the OM and NOM groups. Among 43 patients with residual omentum, 24 (55.8%) recurred, including 9 (20.9%) with omental recurrence. CONCLUSIONS: Histologically occult metastasis was present in one-third of patients undergoing omentectomy during CRS-HIPEC. Omentectomy did not increase the rate of overall morbidity, and one-fifth of patients with residual omentum later developed omental recurrence. Thus, omentectomy is warranted in the absence of gross metastases during CRS-HIPEC.

Proof of Principle of Combining Fluorescence-Guided Surgery with Photoimmunotherapy to Improve the Outcome of Pancreatic Cancer Therapy in an Orthotopic Mouse Model.

BACKGROUND: Pancreatic cancer is a recalcitrant disease in which R0 resection is often not achieved owing to difficulty in visualization of the tumor margins and proximity of adjacent vessels. To improve outcomes, we have developed fluorescence-guided surgery (FGS) and photoimmunotherapy (PIT) using a fluorescent tumor-specific antibody. METHODS: Nude mice received surgical orthotopic implantation (SOI) of the human pancreatic cancer cell line BxPC-3 expressing green fluorescent protein. An anti-carcinoembryonic antigen-related cell adhesion molecule (CEACAM) monoclonal antibody (6G5j) was conjugated to the 700-nm fluorescent dye IR700DyeDX (6G5j-IR700DX). Three weeks after SOI, 16 mice received 50 µg 6G5j-IR700DX via the tail vein 24 h before surgery and were randomized to two groups: FGS-only (n = 8) and FGS + PIT (n = 8). All tumors were imaged with the Pearl Trilogy imaging system and resected under the guidance of the FLARE imaging system. The FGS + PIT group received PIT of the post-surgical bed at an intensity of 150 mW/cm2 for 30 min. Mice were sacrificed 4 weeks after initial surgery, and tumors were imaged with a Dino-Lite digital microscope, excised, and weighed. RESULTS: The 6G5j-IR700DX dye illuminated the orthotopic pancreatic tumors for FGS and PIT. The metastatic recurrence rate was 100.0% for FGS-only and 25.0% for FGS + PIT (p = 0.007). The average total recurrent tumor weight was 2370.3 ± 1907.8 mg for FGS-only and 705.5 ± 1200.0 mg for FGS + PIT (p = 0.039). CONCLUSIONS: FGS and adjuvant PIT can be combined by using a single antibody-fluorophore conjugate to significantly reduce the frequency of pancreatic cancer recurrence.

An Ex Vivo Organotypic Culture Platform for Functional Interrogation of Human Appendiceal Cancer Reveals a Prominent and Heterogenous Immunological Landscape.

PURPOSE: Epithelial neoplasms of the appendix are difficult to study preclinically given their low incidence, frequent mucinous histology, and absence of a comparable organ in mice for disease modeling. Although surgery is an effective treatment for localized disease, metastatic disease has a poor prognosis as existing therapeutics borrowed from colorectal cancer have limited efficacy. Recent studies reveal that appendiceal cancer has a genomic landscape distinct from colorectal cancer and thus preclinical models to study this disease are a significant unmet need. EXPERIMENTAL DESIGN: We adopted an ex vivo slice model that permits the study of cellular interactions within the tumor microenvironment. Mucinous carcinomatosis peritonei specimens obtained at surgical resection were cutoff using a vibratome to make 150-µm slices cultured in media. RESULTS: Slice cultures were viable and maintained their cellular composition regarding the proportion of epithelial, immune cells, and fibroblasts over 7 days. Within donor specimens, we identified a prominent and diverse immune landscape and calcium imaging confirmed that immune cells were functional for 7 days. Given the diverse immune landscape, we treated slices with TAK981, an inhibitor of SUMOylation with known immunomodulatory functions, in early-phase clinical trials. In 5 of 6 donor samples, TAK981-treated slices cultures had reduced viability, and regulatory T cells (Treg). These data were consistent with TAK981 activity in purified Tregs using an in vitro murine model. CONCLUSIONS: This study demonstrates an approach to study appendiceal cancer therapeutics and pathobiology in a preclinical setting. These methods may be broadly applicable to the study of other malignancies.