Tumor Implantation Research Articles

Promoting wound recovery through stable intestinal flora: Reducing post-operative complications in colorectal cancer surgery patients.

In recent years, the relationship between intestinal flora and post-operative recovery, particularly in colorectal cancer (CRC) surgery patients, it has been hypothesized that intestinal flora stability influences wound healing, reduces complications and improves overall recovery outcomes after surgical interventions. This study examined the relationship between intestinal flora stability and post-operative recovery in patients undergoing CRC surgery. Between May 2020 and 2023, 80 CRC patients from our hospital's Colorectal Surgery Department were enrolled. A random number table was used to divide them into two categories. Both groups were subjected to distinct gastrointestinal preparation protocols. Indicators of clinical therapeutic effect, intestinal flora balance following surgery, post-operative complications and quality of life were evaluated. The observation group, which adhered to a distinct gastrointestinal regimen, demonstrated a statistically significant improvement in post-operative outcomes, with a clinical effectiveness rate of 97.5% compared to the control group's 75%. In addition, the observation group had a lower incidence of intestinal flora imbalance following surgery than the control group. The observation group had lower incidences of intestinal obstruction, infection, anastomotic leakage, incisional tumour implantation and delayed diarrhoea. Using the KPS score and the BMI, post-treatment assessments of the observation group's quality of life revealed significant enhancements in comparison to the control group. Additionally, wound healing rates were superior in the observation group, with a correlation between stable intestinal flora and decreased wound infection rates. The type of post-operative diet influenced the stabilization of the gut flora, with a high-fibre diet producing superior results in both groups. The stability of intestinal flora influences the post-operative rehabilitation of patients undergoing CRC surgery favourably. Appropriate bowel preparation and dietary considerations can reduce post-operative complications, improve wound healing rates and enhance overall quality of life.

Abstract A066: TUSC2 immunogene therapy enhances checkpoint blockade through increased cytotoxic immune activation in chemo-resistant small cell lung cancer (SCLC) in humanized mice

Abstract Immunotherapy has been effective but has had limited effect in clinical trials for SCLC. We identified TUSC2, a potent tumor suppressor gene, as a novel immunogene, which mediates both apoptosis and induces a strong antitumor immune response. TUSC2 expression is reduced in almost all SCLC tumors and absent in 41%. We investigated the antitumor immune response to TUSC2 gene therapy in combination with immune checkpoint blockade (ICB) against a chemo-resistant inflamed SCLC tumors in humanized mice. Colony formation was markedly reduced in platinum resistant inflamed H841 cells transfected with TUSC2. Humanized mice were generated by transplanting fresh human cord blood derived CD34 stem cells into sub-lethally irradiated NSG mice(hu-NSG). The level of engraftment of human CD45, CD3 T, CD19 B, NK cells was verified before tumor implantation at > 25%. Subcutaneous tumors were developed in hu-NSG mice and treated with intravenous injections of TUSC2 loaded cationic lipid nanoparticles (quaratusugene ozeplasmid abbreviated quar oze) with or without pembrolizumab (pembro; anti-PD1). A dramatic antitumor effect was mediated by quar oze, whereas pembro remained ineffective. A synergistic antitumor effect was found when quar oze was combined with pembro. The antitumor effect of the quar oze + pembro was associated with increased infiltration of human TILs, CD3 T, cytotoxic T, and NK cells, and a decreased number of human regulatory T (Treg) cells, and PD1 expressing exhausted CD8 T cells in the tumor microenvironment. Quar oze was also combined with atezolizumab (atezo; anti-PD-L1) and the antitumor effect on H841 lung metastases in hu-NSG mice was tested. Metastases were treated with quar oze and atezo alone or in combination. Although quar oze alone and atezo alone showed a strong antitumor effect in controlling metastases, a greater antitumor effect was found when quar oze was combined with atezo. Infiltration of human CD45, CD3 T, CD8 T and NK cells increased in the quar oze and quar oze +atezo treated groups compared with others. A significantly higher number of CD8 T effector memory and lower number of naïve T cells were found in the quar oze +atezo which were associated with increased activated CD8 T cells (CD69+, PD1+ CD8 T cells). HLA-DR+ dendritic cells were increased, whereas myeloid derived suppressor cells were strongly inhibited by the combination. Quar oze was also combined with carboplatin+atezo which showed enhanced antitumor efficacy compared with carbo+atezo or quar oze alone. When quar oze was combined with carboplatin, a greater effect was found in inhibiting H841 cell growth, colony formation, and induction of apoptosis. Quar oze was combined with NPRL2, another tumor suppressor gene, in H841 tumors in humanized mice. Synergistic antitumor efficacy of the dual gene therapy occurred with the quar oze +NPRL2 treatment. Taken together, these data suggest that TUSC2 gene therapy in combination with ICB induces strong antitumor activity on a chemo-resistant inflamed SCLC through cytotoxic CD8 T and NK cell activation. Citation Format: Ismail M Meraz, Mourad Majidi, Renduo Song, Feng Meng, Lihui Gao, Qi Wang, Jing Wang, Elizabeth Shpall, Mark Berger, Hemant Kumar, Jack A Roth. TUSC2 immunogene therapy enhances checkpoint blockade through increased cytotoxic immune activation in chemo-resistant small cell lung cancer (SCLC) in humanized mice [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A066.

Development of a Novel Solid Tumor-Bearing Humanized Animal Model for Simultaneously Evaluating the Toxicity and Efficacy of Bispecific T Cell Engager

The development of novel therapeutics for cancer immunotherapy is tightly restricted by using human samples to estimate the drug toxicity before moving to clinical trials. Currently numerous tumor-bearing animal models have been utilized to test the efficacy of anti-tumor drugs. However, the success rate remains low in the development of clinical treatment. One prominent reason is that the utilized animal models could not accurately predict the toxic response of human immune system to the drugs. Thus, establishing a predictive nonclinical animal platform that can detect potential unwanted toxicity to human patient will be critical for improving the safety of immune drug development. Previously, we have demonstrated a disseminated tumor-bearing humanized mouse model that can evaluate the toxicity and efficacy of bispecific T cell engager (BiTE). Here we aim to develop a novel tumor-bearing mouse model that can simultaneously evaluate the long-term efficacy against solid tumor in addition to cytokine level assessment. In this study, we co-engrafted disseminated and solid tumor cells to the same mice and compared with mice engrafted with disseminated tumor or solid tumor. Three donors were tested. Method: Human triple negative breast cancer MDA-MB-231/Luciferase-2A-GFP (MDA) cell line is epidermal growth factor receptor (EGFR) positive and is labeled with luciferin. The cells were implanted into PBMC humanized NSG-MHC class I/II double knock out (DKO) mice via orthotopic injection into mammary fat pad (MFP, 5x10 6 cells/mouse) and/or via intravenous (IV, 1x10 6/mouse) injection. Disseminated MDA cells normally colonize lung of mice after IV injection. Following EGFRxCD3 BiTE dosing initiation, tumor burden in MFP and lung were evaluated by a in vivo Xenogen imaging system, and solid tumor volume in MFP was measured 2 to 3 times a week by a digital caliper. To evaluate the toxicity levels in response to EGFRxCD3 BiTE treatment, the level of inflammatory cytokine levels in serum of mice were analyzed by BD cytometric bead array. Clinical observations, body weight change, and human immune cell activation were also monitored for drug toxicity assessment. Results: EGFRxCD3 BiTE treatment induced elevated human inflammatory cytokines in serum from humanized mice implanted with combined MFP and IV tumor. By comparison, the serum cytokine levels were low in mice implanted with MDA cells via MFP alone, suggesting that IV injection of tumor cells is required for cytokine production induced by EGFRxCD3 BiTE. MFP solid tumor continued to grow in the PBS control group and EGFRxCD3 BiTE treatments significantly inhibited solid tumor growth regardless the presence of IV implanted with MDA cells. Conclusion: Without disseminated tumor, MFP solid tumor-bearing mice served as a model for efficacy but did not produce inflammatory cytokines after treatment with EGFRxCD3 BiTE. Combination of solid and disseminated tumor implantation provides a new tumor inoculation approach that can be used for simultaneously evaluating the toxic cytokine release and long-term efficacy of immunotherapy drugs. This is a promising preclinical platform to define optimal approaches for clinical cancer treatment.

Assessment of hypoxia and oxidative-related changes in a lung-derived brain metastasis model by [64Cu][Cu(ATSM)] PET and proteomic studies

BackgroundBrain metastases (BM) are the most frequent malignant brain tumors. The aim of this study was to characterize the tumor microenvironment (TME) of BM and particularly hypoxia and redox state, known to play a role in tumor growth and treatment resistance with multimodal PET and MRI imaging, immunohistochemical and proteomic approaches in a human lung cancer (H2030-BrM3)-derived BM model in rats.ResultsFirst, in vitro studies confirmed that H2030-BrM3 cells respond to hypoxia with increasing expression of HIF-1, HIF-2 and their target genes. Proteomic analyses revealed, among expression changes, proteins associated with metabolism, oxidative stress, metal response and hypoxia signaling in particular in cortical BM. [64Cu][Cu(ATSM)] PET revealed a significant uptake by cortical BM (p < 0.01), while no uptake is observed in striatal BM 23 days after tumor implantation. Pimonidazole, HIF-1α, HIF-2α, CA-IX as well as GFAP, CTR1 and DMT1 immunostainings are positive in both BM.ConclusionOverall, [64Cu][Cu(ATSM)] imaging and proteomic results showed the presence of hypoxia and protein expression changes linked to hypoxia and oxidative stress in BM, which are more pronounced in cortical BM compared to striatal BM. Moreover, it emphasized the interest of [64Cu][Cu(ATSM)] PET to characterize TME of BM and depict inter-metastasis heterogeneity that could be useful to guide treatments.

Lactate promotes HMGB1 phosphorylation and release via Akt signaling pathway in gastric cancer cells HGC-27

Objective: To investigate the molecular mechanism of how lactate induces high mobility group box 1 (HMGB1) release. Methods: Gastric cancer HGC-27 cells were divided into the control group and the lactate group (The cells were treated with lactate for 6 h). The level of HMGB1 in the cell culture medium was detected by enzyme-linked immunosorbent assay (ELISA), the localization of HMGB1 was detected using laser confocal microscopy, and the nuclear translocation of HMGB1 was detected using the nucleoplasmic separation assay. The phosphorylation and acetylation levels of HMGB1 were determined by co-immunoprecipitation, and Western blot was used to measure the phosphorylation of Akt and protein kinase C (PKC). HGC-27 cells were first treated with lactate and LY294002, the inhibitor of Akt, and then the phosphorylation of HMGB1 and Akt was analyzed by co-immunoprecipitation and Western blot, respectively. The localization of HMGB1 in cells was detected by laser confocal microscopy. EdU and Transwell assays were used to detect the proliferation and migration abilities of HGC-27 cells, respectively. HGC-27 cells were then injected into the BALB/C null mice for subcutaneous tumor implantation. Mice in the lactate group were intraperitoneally injected with lactate (0.2 g/kg/2 d), while those in the control group were intraperitoneally injected with an equal amount of PBS for 20 consecutive days. ELISA was used to detect the HMGB1 levels in the blood samples taken from the medial canthus vein of the mice, while co-immunoprecipitation and Western blot were used to detect the phosphorylation of HMGB1 and Akt in tumor tissue proteins, respectively. Results: The release levels of HMGB1 in the lactate group were (2 995.00±660.91) pg/ml and (696.33±22.03) pg/ml, after lactate treatment for 6 h and 12 h, respectively, both higher than those in the control group (485.00±105.83) pg/ml (P<0.001 and P=0.028, respectively). After lactate treatment for 6 h, the relative expression of HMGB1 protein in the cytoplasm of HGC-27 cells was 1.13±0.09, higher than that of the control group (0.83±0.07, P=0.001), while the relative expression of HMGB1 in the nucleus was 0.79±0.06, lower than that of the control group (1.07±0.06, P=0.007). The phosphorylation level of HMGB1 reached 1.41±0.09, which was higher than that of the control group (0.97±0.10, P=0.031). The phosphorylation level of Akt was 11.16±0.06, higher than that of the control group (0.91±0.022, P=0.002). The phosphorylation level and nuclear translocation of HMGB1 induced by lactate decreased obviously after Akt inhibition; the proliferation and migration abilities induced by lactate were also obviously inhibited after Akt inhibition. In vivo, the HMGB1 level in the peripheral blood was (1 280.70±389.66) pg/ml in the lactate group, which was obviously higher than that in the control group (595.11±44.75) pg/ml (P=0.008), and the phosphorylation levels of HMGB1 and Akt in tumor tissues in the lactate group were obviously enhanced compared with the control group. Conclusion: Lactate induces HMGB1 release through enhancing HMGB1 phosphorylation via the Akt signaling pathway.

Survival following complete resection of neuroblastoma in novel orthotopic rat xenograft model

Neuroblastoma accounts for 15% of pediatric cancer deaths, despite multimodal therapy including surgical resection. Current neuroblastoma rodent models are insufficient for studying the impact of surgery and combination treatments, largely due to the small size of mouse models. Human neuroblastoma SK-N-BE(2) cells were injected into the left adrenal gland of 5–6-week-old RNU homozygous nude rats. Rats were either monitored by MRI until humane endpoint was reached or after 5 weeks underwent operative tumor resection, followed by monitoring for recurrence and survival. Following neuroblastoma cell implantation, the majority of tumors grew to greater than 5000 mm3 within 5.5–6.5 weeks, meeting the humane endpoint. Surgical resection was successfully done in 8 out of 9 rats, extending survival following tumor implantation from a median of 42 days to 78 days (p < 0.005). Pathology was consistent with human neuroblastoma, showing small round blue cell tumors with Homer-Wright rosettes, high mitoses and karyorrhectic index, and strong PHOX2B staining. Thus, we have established a novel orthotopic xenograft rat model of neuroblastoma and demonstrated increased survival of rats after surgical tumor resection. This model can be used for the development of surgical techniques, such as the use of intraoperative molecular imaging or assessment of combination therapies that include surgery.

Aitongping patch could alleviate cancer pain via suppressing microglia activation and modulating the miR-150-5p/CXCL12 signaling.

We aimed to investigate the pharmacological effects and mechanisms of the Aitongping formula for treating cancer pain. We enrolled 60 cancer patients with Numeric Rating Scale above 4 and grouped them randomly as a Control group (N= 30) and a Patch group (N= 30). We also established bone cancer mice models via tumor implantation. And the animal groups were established as a Sham group, a tumor cell implantation (TCI) group, a TCI + Patch group, and a Patch group. After the validation of successful tumor implantation, we identified candidate miRNAs and genes that were dysregulated in TCI mice and compared their expressions between different mice groups. We also observed the effect of Aitongping patch in vitro in mice primary microglia. The time to disease progression and cancer stability were prolonged by Aitongping patch in cancer patients. And the daily morphine dose was lower, and patients' quality of life was improved in the Patch group. Moreover, Aitongping patch alleviated cancer pain and inhibited microglia activation after the successful implantation of bone tumor in TCI mice. We also observed the dysregulation of miR-150-5p and chemokine CXC motif ligand 12 (CXCL12) mRNA in TCI mice. And CXCL12 was found to be targeted by miR-150-5p. Aitongping patch was found to upregulate miR-150-5p and downregulate CXCL12 in vivo and in vitro. Aitongping patch could alleviate cancer pain via suppressing microglia activation, and the downregulation of miR-150-5p, as well as the upregulation of CXCL12 mRNA and protein, induced by tumor implantation or lipopolysaccharide stimulation, was restored by Aitongping treatment.

Transurethral Hem-o-lok Clip Ligation of the Distal Ureter in Retroperitoneal Laparoscopic Radical Nephroureterectomy

Background and Objective: Distal ureter management is an essential part of radical nephroureterectomy (RNU). However, there is no agreement on the optimal surgical treatment for ureter and bladder cuff excision. The classical “pluck” technique following transurethral resection of the intramural ureter increases the risk of extravesical and intravesical tumor cell spillage. We aimed to provide a simple transurethral technique with the Hem-o-lok clip ligation for the management of the distal ureter during retroperitoneal laparoscopic RNU. Methods: Transurethral resection of the bladder cuff was performed using a bipolar β electrode mounted on resectoscope. Subsequently, a Super Scope (S-scope) with a 5.6-mm diameter working channel was used with a clip applier to deliver the 5-mm Hem-o-lok clips, which consequently ligated the ureteral stump and avoided urine spillage from the upper tract. Traditional retroperitoneal laparoscopic surgery was used to treat the renal and upper ureter. The resected distal ureter and the Hem-o-lok clip were gently pulled out of the bladder by the “pluck” technique. Results: A total of 14 upper tract urothelial carcinoma patients were analyzed, including 10 men and 4 women. The Hem-o-lok clip ligation took less than 20 s. In each patient, the clip was clearly visible and attached tightly to the ureter, and a clear distal ureter was observed in all patients. Histopathology results showed pT2 in 8 and pT3 in 6 patients. A median follow-up of 15 months revealed no extravesicular or intravesicular recurrences. Conclusions: Transurethral Hem-o-lok clip ligation technique provides a simple and safe option for distal ureter management in retroperitoneal laparoscopic RNU. This novel approach enables construction of a watertight system of the upper urinary tract, preventing the spread of tumor cells effectively and minimizing local tumor implantation risk.

Patient Characteristics Associated with Growth of Patient-Derived Tumor Implants in Mice (Patient-Derived Xenografts).

Background: patient-derived xenografts (PDXs) have defined the field of translational cancer research in recent years, becoming one of the most-used tools in early drug development. The process of establishing cancer models in mice has turned out to be challenging, since little research focuses on evaluating which factors impact engraftment success. We sought to determine the clinical, pathological, or molecular factors which may predict better engraftment rates in PDXs. Methods: between March 2017 and January 2021, tumor samples obtained from patients with primary or metastatic cancer were implanted into athymic nude mice. A full comprehensive evaluation of baseline factors associated with the patients and patients' tumors was performed, with the goal of potentially identifying predictive markers of engraftment. We focused on clinical (patient factors) pathological (patients' tumor samples) and molecular (patients' tumor samples) characteristics, analyzed either by immunohistochemistry (IHC) or next-generation sequencing (NGS), which were associated with the likelihood of final engraftment, as well as with tumor growth rates in xenografts. Results: a total of 585 tumor samples were collected and implanted. Twenty-one failed to engraft, due to lack of malignant cells. Of 564 tumor-positive samples, 187 (33.2%) grew at time of analysis. The study was able to find correlation and predictive value for engraftment for the following: the use of systemic antibiotics by the patient within 2 weeks of sampling (38.1% (72/189) antibiotics- group vs. 30.7% (115/375) no-antibiotics) (p = 0.048), and the administration of systemic steroids to the patients within 2 weeks of sampling (41.5% (34/48) steroids vs. 31.7% (153/329), no-steroids) (p = 0.049). Regarding patient's baseline tests, we found certain markers could help predict final engraftment success: for lactate dehydrogenase (LDH) levels, 34.1% (140/411) of tumors derived from patients with baseline blood LDH levels above the upper limit of normality (ULN) achieved growth, against 30.7% (47/153) with normal LDH (p = 0.047). Histological tumor characteristics, such as grade of differentiation, were also correlated. Grade 1: 25.4% (47/187), grade 2: 34.8% (65/187) and grade 3: 40.1% (75/187) tumors achieved successful growth (p = 0.043), suggesting the higher the grade, the higher the likelihood of success. Similarly, higher ki67 levels were also correlated with better engraftment rates: low (Ki67 < 15%): 8.9% (9/45) achieved growth vs. high (Ki67 ≥ 15%): 31% (35/113) (p: 0.002). Other markers of aggressiveness such as the presence of lymphovascular invasion in tumor sample of origin was also predictive: 42.2% (97/230) with lymphovascular vs. 26.9% (90/334) of samples with no invasion (p = 0.0001). From the molecular standpoint, mismatch-repair-deficient (MMRd) tumors showed better engraftment rates: 62.1% (18/29) achieved growth vs. 40.8% (75/184) of proficient tumors (p = 0.026). A total of 84 PDX were breast models, among which 57.9% (11/19) ER-negative models grew, vs. 15.4% (10/65) of ER-positive models (p = 0.0001), also consonant with ER-negative tumors being more aggressive. BRAFmut cancers are more likely to achieve engraftment during the development of PDX models. Lastly, tumor growth rates during first passages can help establish a cutoff point for the decision-making process during PDX development, since the higher the tumor grades, the higher the likelihood of success. Conclusions: tumors with higher grade and Ki67 protein expression, lymphovascular and/or perineural invasion, with dMMR and are negative for ER expression have a higher probability of achieving growth in the process of PDX development. The use of steroids and/or antibiotics in the patient prior to sampling can also impact the likelihood of success in PDX development. Lastly, establishing a cutoff point for tumor growth rates could guide the decision-making process during PDX development.

EXTH-39. D2C7-CAR: A NOVEL, DUAL-SPECIFIC CHIMERIC ANTIGEN RECEPTOR T CELL WITH HIGH SPECIFICITY FOR EGFR AND EGFRVIII IMPROVES SURVIVAL IN EGFR/EGFRVIII GLIOBLASTOMA AND EGFR OVER-EXPRESSING MEDULLOBLASTOMA

Abstract BACKGROUND GBM is the most common primary malignant brain tumor found in adults. Despite strenuous efforts at improving outcomes, overall survival remains dismal (15-20 months). D2C7-CAR is a dual specific CAR T cell that targets EGFR and EGFRvIII. We performed pre-clinical analysis of D2C7-CAR glioblastoma and other EGFR aberrant tumor models to assessed efficacy and safety. METHODS U87 and U87vIII glioblastoma and DAOY medulloblastoma cell lines were characterized by flow cytometry to evaluate for EGFR and EGFRvIII expression. Cytotoxicity assays were performed utilizing flow cytometry on serially diluted effector: target ratios of U87, U87vIII, and DAOY mixed with D2C7 CAR. U87 and U87vIII was orthotopically implanted into the frontal lobe and DAOY was orthotopically implanted into the frontal lobe and posterior fossa of NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ (NSG) mice. After tumor implantation, D2C7 CAR, vIII CAR, or Mock CAR was introduced within the tumor bed. Survival was measured and analyzed using the Log-rank test. Bioluminescence with IVIS imaging of CT2AVIII with luciferase was utilized to perform time point analysis of IC tumor response to treatment vs control. Toxicity against somatic tissue EGFR expression was assessed by in vitro cytotoxicity assay as described above. RESULTS EGFR was detected in U87, U87vIII, and DAOY on flow analysis. EGFRvIII was expressed only on U87vIII. D2C7 CAR demonstrated effective in vitro cytotoxicity against all three cell lines with &amp;gt;90% cytotoxicity achieved at an effector: target ratio of 2.5:1. In vivo, D2C7 CAR significantly prolonged survival compared to treatment with mock and vIII CAR when tumor was implanted intracranially. Bioluminescence imaging demonstrated robust tumor response. D2C7 was not cytotoxic when co-cultured with EGFR expressing human keratinocytes. CONCLUSION D2C7-CAR demonstrates effective preclinical results both in vitro and in vivo. D2C7-CAR is not cytotoxic against human keratinocytes, suggesting it will be well tolerated in clinical trials.

MODL-19. DEVELOPMENT OF A RECURRENT GLIOBLASTOMA MURINE MODEL FOLLOWING SURGICAL RESECTION: INVESTIGATING THE TUMOR-IMMUNE MICROENVIRONMENT TO EVALUATE NOVEL PERIOPERATIVE THERAPIES

Abstract BACKGROUND Most glioblastoma (GBM) patients experience tumor recurrence following standard-of-care treatment which includes tumor resection, radiation, and chemotherapy with concomitant and adjuvant temozolomide. Currently, no murine surgical GBM resection models to evaluate novel therapies exist and understanding of postsurgical tumor microenvironment (TME) has yet to be fully elucidated in pre-clinical GBM models. METHODS GL261 GBM cells were orthotopically implanted in C57BL/6 mice on day 1. On day 14, tumor resection was performed using the NICO Murine Neuroscience System, an automated, intraoperative, pre-clinical surgical resection system designed to minimize damage to surrounding tissue thus preventing the need for animal sacrifice. Standard T2-MRI and Terason uSmart 3200T ultrasound system were used to analyze tumor size following resection and recurrent growth. Immunological and biochemical assays were performed to explore local TME. RESULTS We observed that surgically resected GL261 GBM mice survived 55 + 8 days whereas mice with unresected GBM survived 35 + 7 days following tumor implantation. This new preclinical surgical resection recurrent immunocompetent GBM (Sur-rGBM) model was used for analyzing TME. Our results demonstrated significant changes in TME, such as an increase in astrocytic activation (GFAP+), increased microglia/macrophage (CD11b+, and IBA-1+) infiltration to surrounding tissue, increase in M2 macrophage (TGM2+ and CCL22+) and NK regulatory cells (CDC 26 +), and increased angiogenesis (VEGF) in Sur-rGBM as compared to unresected GBM. We also observed increased proliferation (Ki-67) and upregulation of stem cell markers CD133, Nestin, and Olig2 at the protein level. CONCLUSION Our data demonstrated the upregulation of tumor-promoting activation factors in Sur-rGBM as compared to unresected GBM. Currently, the Sur-rGBM model does not fully resemble the entire treatment regimen offered to GBM patients. Thus, our future aim is to further refine this resection model and assess adjuvant therapies at different time points along disease progression without needing to sacrifice the animal for analysis of tissue.

TMIC-67. GLIOBLASTOMA AUGMENTS SYSTEMIC IMMUNUNOSUPPRESSION UPON LOSS OF TESTOSTERONE VIA ALTERATION OF GLUCOCORTICOIDS PRODUCTION

Abstract While sex differences in incidence, genetics, and immune changes are established in glioblastoma (GBM), the specific contribution of sex hormones to these differences has not been fully explored. Testosterone has been shown to have a pro-tumorigenic effect on human and mouse GBM tumor cells. However, the systemic effect of testosterone in an immune competent model has not been tested. To test this, we performed castration or sham surgery on C57BL/6 male mice, followed by intracranial implantation of syngeneic glioma cells. Surprisingly, castrated mice exhibited more aggressive tumor growth compared to sham surgery controls, and this castration-induced aggressiveness could be reversed by administering exogenous testosterone. This finding was further confirmed by chemically blocking androgen receptor signaling using enzalutamide. We observed a significant increase in adrenocorticotropic hormone (ACTH) levels in the serum from castrated mice compared to the sham group after tumor implantation. Additionally, mass spectrometry analysis detected elevated levels of circulating glucocorticoids in castrated mice, and pharmacological blockade of glucocorticoid receptor using mifepristone reversed the shorted survival in castrated mice, but not in sham control. Flow analysis revealed decreased production of anti-tumor cytokines such as IFN-γ and TNF-α in CD4+ and CD8+ T cells from tumors and lymph nodes in castrated mice, suggesting systemic immunosuppression in these animals. Indeed, castration of immune-compromised mice, specifically NSG and RAG1KO strains, did not result in reduced survival. Moreover, when GBM cells were subcutaneously implanted into the flank, tumor growth in castrated mice was decelerated compared to sham controls. We also observed significantly lower ACTH levels in the flank tumor model compared to the brain tumor model, indicating a brain-specific effect of steroid hormones on tumor control. Taken together, these findings demonstrate that testosterone regulates T cell function through glucocorticoids, ultimately affecting GBM growth in a site-specific manner.

IMMU-36. PD-1KO HEMATOPOIETIC STEM CELLS RAPIDLY DIFFERENTIATE INTO GLIOMA-INFILTRATING EFFECTOR T-CELLS

Abstract INTRODUCTION We previously published that hematopoietic stem cell combination therapy (HSC+aPD1) extends survival in murine CNS malignancies, including glioma. To better understand lymphoid-specific mechanisms, we analyzed various lymphoid tissues in a murine glioma model. We hypothesize early PD-1 blockade in HSCs influences later differentiation trajectories. Transferred HSCs differentiate into T-cells within the thymus and then migrate to the intracranial tumor microenvironment as anticipated. Indeed, blocking PD-1/PD-L1 signaling during HSC differentiation significantly impacts subsequent T-cell maturation. Remarkably, TILs derived from HSCPD1KO cells were biased towards CD4+ Treg or CD8+ effector lineages, whereas HSCPD1+/+ progeny leaned toward immature/naïve cell states. METHODS HSCs were prepared from constitutive GFP-expressing (CD45.2+) and PD1KO (CD45.2+) mice and transferred into CD45.1+ hosts. Sublethal 5Gy total body irradiation was administered day 5 post-intracranial tumor implantation. The next day, 1e6 HSCs from a 1:1-GFP:PD1KO cocktail were injected intravenously. Descriptive statistics are reported as mean ± SD. Transferred HSCs engraft, expand, differentiate, tended and migrate to form approximately 25% of the TIL compartment in only 15 days. RESULTS We found that, 56.2% ± 20.3 of CD3+ TILs display an immature CD4+CD8+ (DP) phenotype in early disease, and 43.8% ± 17.4 of these DP-TILs are HSC-derived. DP-TILs were virtually absent in advanced disease 29 days after treatment, but HSC-derived TILs most commonly fell within the single-positive (SP) TIL subsets, comprising 9.8% ± 5.6 of SP-CD8+ TILs. Notably, HSCPD1KO-derived cells were 4x more abundant amongst SP-CD8 TILs when compared to HSCGFP-derived cells (6.5% vs 1.6%, p &amp;lt; 0.05). SP-CD8 thymocytes were similarly enriched for HSCPD1KO progeny (41.1% vs 24.7%, p &amp;lt; 0.05) suggesting that PD-1 blockade impacts thymopoiesis directly. CONCLUSION PD-1 signaling modulates thymic output. Blocking the PD-1/PD-L1 axis during thymopoiesis increases the abundance of HSC-derived CD8+ effectors at the tumor site. HSC+aPD1 therapy is uniquely positioned to leverage thymus-dependent anti-tumor immunity.

EXTH-52. LONG-ACTING RECOMBINANT INTERLEUKIN-7, NT-I7, IMPROVES SURVIVAL FOLLOWING ONCOLYTIC ZIKA VIRUS TREATMENT IN THE SB28 IMMUNOSUPPRESSIVE AND TREATMENT-RESISTANT MURINE GLIOMA MODEL

Abstract Glioblastoma (GBM) does not respond to immunotherapy for several reasons, including limited cancer-specific neoantigens and poor T-cell infiltration. The SB28 murine glioma model recapitulates these aspects of human GBM. Zika virus (ZIKV) treatment of GL261 and CT2A-bearing mice resulted in significant survival improvement through multiple mechanisms, including direct tumor killing and induction of a local CD8+ T-cell anti-tumor response, but ZIKV is less effective against SB28 tumors. Previously, we published that a long-acting human IL-7, rhIL-7-hyFc (NT-I7, efineptakin alfa; NeoImmuneTech Inc.), increases T-cell abundance and improves tumor infiltration. Therefore, we hypothesize that combining NT-I7 with oncolytic ZIKV therapy will enhance the anti-tumor response and improve survival in mice bearing SB28 syngeneic tumors. 1×103 SB28 tumor cells were intracranially implanted in C57BL/6J mice. Mice were treated with NT-I7 on post tumor implantation day 7 and 10, followed by intratumoral ZIKV on day 14. Tumor burden was assessed using bioluminescence imaging; mice were monitored for survival and bled weekly to assess the systemic T-cell response to NT-I7. Subcutaneous injection of NT-I7 significantly boosted systemic T-cell abundance compared to control (5,623 cells/uL vs. 136 cells/uL, p &amp;lt; 0.05), particularly cytotoxic CD8+ T-cells (4,776 cells/uL vs. 47 cells/uL, p &amp;lt; 0.05). This increased abundance of CD8+ T-cells peaked at 7 days after initial treatment and persisted for 21 days. NT-I7 monotherapy did not confer any survival benefit. However, the combination of NT-I7 and ZIKV treatment resulted in significant improvement in survival compared to NT-I7 or ZIKV treatment alone (p &amp;lt; 0.05). Treatment with NT-I7 primes the immune system by expanding the circulating CD8+ T-cell population by 100-fold. Timing the oncolytic ZIKV injection with the peak in peripheral CD8+ T-cells greatly improved survival in the immunotherapy resistant SB28 glioma model. These data suggest a role for NT-I7 as an adjunct to various T-cell mediated treatment strategies for GBM.

Platelet Angiopoietin-1 Protects Against Experimental Lung Metastasis By Limiting Tumor Cell Extravasation

In addition to their fundamental roles in hemostasis, platelets can contribute to both tumor growth and metastasis. However, despite being a reservoir for pro-angiogenic and metastatic cytokines, platelets also harbor negative regulators of tumor progression. One such regulator is angiopoietin-1 (Angpt1), an angiogenic cytokine that preserves vascular integrity by promoting cell-cell endothelial interactions downstream of its receptor, the receptor tyrosine kinase Tie-2. In addition, Angpt1 also protects against tumor cell metastasis through an unidentified mechanism. Although platelets are believed to be the primary source of Angpt1 in circulation, the contributions of platelet-derived Angpt1 to tumor growth and metastasis have not been investigated. In this study, we demonstrate that platelet Angpt1 is selectively upregulated in the spontaneous PyMT breast cancer mouse model, but not pre-clinical models of melanoma or non-malignant inflammation (colitis), suggesting a distinct contribution of platelet Angpt1 in breast cancer. To test whether deletion of platelet Angpt1 affects tumor growth or metastasis, we generated mice selectively lacking Angpt1 in megakaryocytes and their platelet progeny (Angpt1 fl/flPF4 Cre, referred to as Angpt1 Plt KO). Plasma Angpt1 was undetectable in Angpt1 Plt KO mice, comparable to mice deficient in the megakaryocyte differentiation factor thrombopoietin, which display approximately 10% of platelet counts. Taken together, these findings establish that platelets are the principal source of circulating Angpt1. In tumor implantation studies, orthotopic tumor growth and vascularization were unaffected in Angpt1 Plt KO mice in pre-clinical models of breast cancer and melanoma. However, Angpt1 Plt KO mice had increased experimental metastasis during both early (3-24 hours) and late (10 days, Figure 1) stages of tumor colonization in both breast cancer and melanoma models, revealing an important role for platelet Angpt1 in restraining the latter stages of tumor metastasis following tumor engraftment. Next, we sought to mechanistically determine how platelet Angpt1 limits tumor cell metastasis. Static adhesion assays demonstrated that platelets lacking Angpt1 did not affect tumor cell attachment to endothelial cells when compared to platelets containing Angpt1. However, Angpt1 Plt KO mice had increased tumor cell retention and extravasation in their lungs following experimental metastasis (3-24 hours), suggesting that platelet Angpt1 limits endothelial permeabilization and the trans-endothelial migration of tumor cells out of blood vessels. Most importantly, all intravascular tumor cells were found within platelet-rich microthrombi immediately after sequestration in the lungs. We therefore conclude that localized Angpt1 released by activated platelets at the site of tumor cell arrest likely reprograms the surrounding endothelium to limit successful tumor cell extravasation. These findings reveal an unexpected role for platelets in restricting tumor cell metastasis.

Pathological features of primary cardiac myxoid tumour in dogs: a review of 11 cases (2002–2022)

This report documents the pathological features of primary cardiac myxoid tumour (MT) in 11 dogs. Macroscopically, all the tumours were located in the tricuspid valve (TV), its septal leaflet being predominantly affected. Therefore, it appears that the TV is the most common site of occurrence for cardiac MT in dogs. Two gross anatomical types of canine valvular MT were evident. Seven of the 11 tumours were round or oval with a smooth or gently lobulated and glistening surface, while the other four were gelatinous, multilobulated and polypoid, with an irregular surface. Microscopically, in nine cases the tumours had an abundant myxoid matrix within which elongated spindle-shaped cells with no remarkable cytological atypia were sparsely embedded, suggesting a benign character (ie, myxoma). In the other two cases the tumours consisted of variably dense, haphazardly arranged, interlacing streams of anaplastic spindle-shaped or polygonal cells containing many mitotic figures, indicative of a malignant form of myxoma (ie, myxosarcoma). Isolated or clustered collections of myxoma cells (eg, cords, rings, syncytia) characteristic of human atrial myxoma were only rarely evident or lacking in all 11 cases, indicating that rarity or absence of such structural features may be specific to valvular MTs. Immunohistochemical findings were indicative of smooth muscle differentiation of the neoplastic cells. Tumour embolization to the intrapulmonary arteries and/or tumour implantation on the endocardium of the right heart chambers was evident only in the four cases of irregular-surfaced MT.

A potential protective role of congenital peritoneal encapsulation coexisting with metastatic colon cancer: a rare case report

Introduction and importance: Congenital peritoneal encapsulation (CPE) is a rare condition in which the small intestine is encased within a mesothelial-lined sac. The following case is an extremely rare description of the co-existence of both colon cancer and peritoneal encapsulation, highlighting the potential role of this co-existence in preventing the spread of metastases and tumor implantation. Case-presentation: A 60-year-old female was diagnosed with metastatic colon cancer. During the operation, a thin fibrous membrane was found covering the small intestine, which suggested CPE. The tumor was removed, and the additional membrane was totally excised. The patient is currently receiving chemotherapy for metastatic treatment and is in good health. Clinical discussion: CPE is a medical condition that results from abnormal peritoneal development, and it is often confused with other differential diagnoses resulting from inflammatory causes. It can occur at different ages and remains asymptomatic for the majority of cases. However, it can be a potential cause of bowel obstruction. An intraoperative diagnosis can easily differentiate the case. The co-existence with colon cancer has been described only once in the literature. Conclusion: Peritoneal encapsulation is a rare, mostly asymptomatic condition. However, it may play a protective role in preventing metastatic colon cancer from affecting the small intestine, thus potentially opening up new avenues for the treatment of cancer metastases.

Surgical experience in cardiac myxomas at a tertiary hospital

IntroductionCardiac myxomas account for 50% of all benign cardiac tumors. Their clinical presentation varies from embolisms to fever. Our objective was to describe the surgical experience in the resection of cardiac myxomas during an 8-year period. MethodsThis is a retrospective, descriptive study of a series of cases with cardiac myxomas diagnosed from 2014 to 2022 at a tertiary care center. Descriptive statistics were used to define the populational and surgical characteristics. We used Pearson’s correlation to study the relationship between postoperative complications and age, tumor size and affected cardiac chamber. Results31 patients were included, with a predominance of females (1:2 ratio). The prevalence was 0.44%, which was calculated based on the number of cardiac surgeries performed in our unit over the 8-year period. The main clinical manifestation was dyspnea (85%, n = 23), followed by cerebrovascular event (CVE) (18%, n = 5). Atriotomy and resection of the pedicle were performed with preservation of the interatrial septum. Mortality was 3.2%. The postoperative evolution was uneventful in 77%. Tumor recurrence occurred in 2 patients (7%), both debuting with embolic phenomena. No association was observed between postoperative complications or recurrence and tumor size, nor aortic clamping and extracorporeal circulation times with regard to age. ConclusionsFour atrial myxoma resections are performed in our unit per year, with an estimated prevalence of 0.44%. The tumor characteristics described coincide with the previous literature. A relationship between embolisms and recurrences cannot be ruled out. Wide surgical resection of the pedicle and base of tumor implantation may influence tumor recurrence, although further studies are needed.

Proteomics, Transcriptomics, and Phosphoproteomics Reveal the Mechanism of Talaroconvolutin-A Suppressing Bladder Cancer via Blocking Cell Cycle and Triggering Ferroptosis

Talaroconvolutin-A (TalaA) is a compound from the endophytic fungus T. convolutispora of the Chinese herbal medicine Panax notoginseng. Whether TalaA exerts anticancer activity in bladder cancer remains unknown. Using CCK8 assay, EdU staining, crystal violet staining, flow cytometry, living/dead cell staining, and Western blotting, we studied the anticancer activity of TalaA in vitro. Moreover, we performed xenograft tumor implantation. The antitumor effects were evaluated through H&E and immunohistochemistry staining. Proteomics was conducted to detect changes in the protein profile; transcriptomics was performed to detect changes in mRNA abundance; phosphoproteomics was used to detect changes in protein phosphorylation. TalaA inhibited tumor cell proliferation, DNA replication, and colony formation in a dose-dependent manner in bladder cancer cells. The IC50 values of TalaA on SW780 and UM-UC-3 cells were 5.7 and 8.2 μM, respectively. TalaA (6.0 mg/kg) significantly repressed the growth of xenografted tumors and did not affect the body weight nor cause obvious hepatorenal toxicity. TalaA arrested the cell cycle by downregulating cyclinA2, cyclinB1, and AURKB and upregulating p21/CIP. TalaA also elevated intracellular reactive oxygen species and upregulated transferrin and heme oxygenase 1 to induce ferroptosis. Moreover, TalaA was able to bind to MAPKs (MAPK1, MAPK8, and MAPK14) to inhibit the phosphorylation of ∗SP∗ motif of transcription regulators. This study revealed that TalaA inhibited bladder cancer by arresting cell cycle to suppress proliferation and triggering ferroptosis to cause cell death. Conclusively, TalaA would be a potential candidate for treating bladder cancer by targeting MAPKs, suppressing the cell cycle, and inducing ferroptosis.

Enhancing Immune-Mediated Radiotherapy Efficacy in Murine Models of Head and Neck Cancer through Peroxisome Proliferator-Activated Receptor Modulation

The tumor microenvironment (TME) in HPV-unrelated head and neck cancer (HNC) is considered to be immunologically "cold," and immunometabolic adaptations to radiotherapy (RT) can exacerbate these conditions and lead to radioresistance. Peroxisome proliferator-activated receptor-α (PPARα) agonism may improve the immune response to RT by reducing glucose scarcity through upregulation of fatty acid utilization in cancer cells. Our clinical trial data shows that high serum oleic acid (OA), a PPAR ligand, correlates with response to radioimmunotherapy. Orthotopic buccal tumor implantations of MOC2 and LY2 HNC cell lines were performed in C57BL/6 and BALB/c mice, respectively. Mice were placed on a high OA diet (38% kcal from OA) 3 weeks prior to tumor implantation. Control diet consisted of 1% kcal from OA. In vitro RT was performed to characterize the metabolic effects on the cancer cell lines. For in vivo studies, tumors were irradiated upon reaching 100 mm^3 with three 8 Gy fractions, given every 4-5 days. The PPARα agonist fenofibrate (FF, 100mg/kg/day) was given via oral gavage or intraperitoneal injection starting 5 days after RT. Tumor volume and overall survival were measured as objective outcomes, and flow cytometry was used to characterize the immune landscape of the tumor, blood, and lymph nodes. Mass spectrometry was employed for bulk proteomics and metabolomics on serum samples, and stable isotope labeling was performed on CD8 T cells from treated mice ex vivo. Extracellular flux analyses were performed on tumor cells and CD8 T cells to determine metabolic phenotypic changes. In vitro cytotoxicity was met for MOC2 and LY2 cancer cells in 100 uM FF and OA in comparison to solvent (p<0.01). Extracellular flux analyses show that RT upregulates the glycolytic phenotype of MOC2 and LY2 cancer cells; and that FF and/or OA decrease the glycolytic capacity of the cancer cells. Ex vivo extracellular flux analyses showed increased glycolytic capacity of CD8 T cells in mice treated with FF in comparison to RT alone. RT in combination with FF significantly improved tumor volume response in comparison to RT alone (mean 99.4 vs 182.7 mm^3, p = 0.001) and was comparable to combination radioimmunotherapy (with anti-PDL1 therapy; mean 99.4 vs. 132.3 mm^3). Unexpectedly, OA negated this improvement in efficacy in both MOC2 and LY2 tumor models; mice on the high OA diet had significantly higher average body weight (p<0.01). Significant changes in adaptive immune response were observed within the TME with the addition of FF. This was mirrored by changes in serum metabolomics. PPARα agonism improved the efficacy of RT in murine HNC models and could be considered in future translational clinical trial design.