Murine Bladder Cancer Cell Research Articles

Abstract IA005: Y chromosome loss in cancer drives growth by evasion of adaptive immunity

Abstract Loss of the Y chromosome (LOY) is observed in 10-40% of bladder cancers, but its clinical and biological significance is unknown. We will present genomic and transcriptomic studies that show LOY correlates with poor prognoses in patients. We performed studies of murine bladder cancer cells with LOY as well as those with deletion of Y chromosome by CRISPR/Cas9 and compared them to cells with and intact Y chromosome as controls. Y+ and Y- tumors grew similarly in vitro, while Y- tumors grew faster than Y+ tumors in immune competent hosts in a T cell-dependent manner. Flow cytometric analyses demonstrated that Y- tumors promote exhaustion of CD8+ T cells in the tumor microenvironment. These findings were supported by data obtained from single-nuclei RNA sequencing and spatial proteomic evaluation of human bladder cancers. Compared to Y+ tumors, Y- tumors exhibited a superior response to anti-PD-1 therapy in mice. In bladder cancer patients those with LOY tumors have better prognosis than those with Y+ tumors. This is the first evidence demonstrating that LOY in tumors alters T cell function by promoting T cell exhaustion and sensitizes them to PD-1-targeted immunotherapy. This work provides novel insights into basic LOY biology as well as the potential for the development of biomarkers for improved cancer immunotherapy. Citation Format: Dan Theodorescu. Y chromosome loss in cancer drives growth by evasion of adaptive immunity [abstract]. In: Proceedings of the AACR Special Conference on Bladder Cancer: Transforming the Field; 2024 May 17-20; Charlotte, NC. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(10_Suppl):Abstract nr IA005.

6]-Shogaol Induces Apoptosis of Murine Bladder Cancer Cells.

Bladder cancer is considered one of the most aggressive neoplasms due to its recurrence and progression profile, and even with the improvement in diagnosis and treatment methods, the mortality rate has not shown a declining trend in recent decades. From this perspective, the search and development of more effective and safer therapeutic alternatives are necessary. Phytochemicals are excellent sources of active principles with therapeutic potential. [6]-Shogaol is a phenolic compound extracted from the ginger rhizomes that has shown antitumor effects in a wide variety of cancer models. However, there is no record in the literature of studies reporting these effects in models of bladder cancer. Thus, this study aimed to investigate the in vitro cytotoxic and pro-apoptotic potential of [6]-Shogaol against murine bladder cancer urothelial cells (MB49). The cytotoxic effects of [6]-Shogaol on cell viability (MTT method), cell morphology (light microscopy), alteration of proliferative processes (clonogenic assay), oxidative stress pathway (levels of reactive oxygen species) and the induction of apoptotic events (flow cytometry and high-resolution epifluorescence imaging) were evaluated in murine urothelial bladder cancer cell lines (MB49), relative to non-tumor murine fibroblasts (L929). The results showed that [6]-Shogaol was able to induce concentration-dependent cytotoxic effects, which compromised cell viability, exhibiting an inhibitory concentration of 50% of cells (IC50) of 146.8 µM for MB49 tumor cells and 236.0 µM for L929 non-tumor fibroblasts. In addition to inhibiting and altering the proliferative processes if colony formation, it presented pro-apoptotic activity identified through a quantitative analysis and the observation of apoptotic phenotypes, events apparently mediated by the induction of nuclear fragmentation. The data presented suggest that [6]-Shogaol has a higher concentration-dependent cytotoxic and apoptosis-inducing potential in MB49 cells than in L929 fibroblasts. These results may contribute to the development of therapeutic alternatives for bladder cancer.

Abstract 1845: Mammalian orthoreoviruses R124 and jin-3 demonstrate oncolytic and immune-stimulatory effects in human preclinical bladder cancer models

Abstract Immunotherapy, including the use of immune checkpoint inhibitors, has emerged as an attractive strategy for treatment of various cancers. Unfortunately, less than half of the bladder cancer patients demonstrate clinical benefit from immune checkpoint inhibitors. Novel therapeutic approaches such as oncolytic virotherapy may unleash the full potential of immunotherapy. Oncolytic viruses display tumor-lysing properties, while leaving normal cells unharmed. Besides the direct oncolytic effects, oncolytic viruses are capable of inducing systemic anti-tumor immune responses, thereby representing a promising anti-cancer therapy. In our multi-center oncolytic viro-immunotherapy (OVIT) consortium we evaluate and compare the oncolytic and immunomodulatory properties of several oncolytic viruses (reoviruses, novel non-human primate Adenoviruses, Newcastle disease virus), develop tools to predict oncolytic virus efficacy and design strategies to personalize oncolytic virus therapy. In this study we evaluated and compared the direct oncolytic and indirect immunostimulatory effects of wildtype reovirus R124 and mutant reovirus jin-3 in human bladder cancer. Mutant reovirus jin-3 harbors mutations in the spike protein Sigma-1 and can infect cells independently of junction adhesion molecule A (JAM-A) expression on the tumor cell surface. For this, we exploited multiple preclinical bladder cancer models, including patient-derived tumor models (e.g. 3D cultures) and ex-vivo cultured tumor tissue slices. Both R124 and jin-3 reoviruses could infect, replicate and induce cell death in a panel of 2D and 3D cultured bladder cancer cells lines with a basal, luminal or mixed phenotype. Furthermore, the viruses were capable of infecting the tumor cells and induced cell death in ex-vivo cultured tumor tissue slices. Reovirus mutant jin-3, and to a lesser extent R124, strongly induced immunogenic cell death markers (HMGB1, cell surface expression of calreticulin, HSP90), interferon-stimulated genes, and inflammatory cytokines (IFNβ, CXCL10, TNFα) in human bladder cancer cells. Co-culture of reovirus-infected murine bladder cancer cells MB-49 with murine splenocytes resulted in increased activation markers of dendritic cells and NK cells. In conclusion, reoviruses display oncolytic properties in multiple preclinical models of human bladder cancer. Mutant reovirus jin-3 displays more potent immunomodulatory responses in preclinical bladder cancer models compared with wildtype reovirus R124. Therefore, jin-3 represents an attractive candidate for clinical translation. Citation Format: Arjanneke F. Van De Merbel, Maaike H. van der Mark, Thijs J. Janssen, Lobke C. Hensen, Diana J. van den Wollenberg, Rob C. Hoeben, Rob F. Bevers, Rob C. Pelger, Gabri van der Pluijm, Geertje van der Horst. Mammalian orthoreoviruses R124 and jin-3 demonstrate oncolytic and immune-stimulatory effects in human preclinical bladder cancer models [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 1845.

Probiotics enhances anti-tumor immune response induced by gemcitabine plus cisplatin chemotherapy for urothelial cancer.

Chemotherapy drugs, such as gemcitabine and cisplatin (GC), are frequently administered to patients with advanced urothelial carcinoma, however the influence of the gut microbiota on their action is unclear. Thus, we investigated the effects of GC on the gut microbiome and determined whether oral supplementation with a probiotics mixture of Lactobacillus casei Shirota and Bifidobacterium breve enhanced the anti-tumor immune response. After subcutaneous inoculation with MBT2 murine bladder cancer cells, syngenic C3H mice were randomly allocated into eight groups. The gut microbiome cluster pattern was altered in both the GC and oral probiotics groups (p=0.025). Both tumor-bearing conditions (no treatment) and GC chemotherapy influenced Pseudoclostridium, Robinsoniella, Merdimonas, and Phocea in the gut. Furthermore, comparison of the GC-treated and GC + probiotics groups revealed an association of four methyltransferase family enzymes and two short-change fatty acid-related enzymes with oral probiotics use. A significant difference in tumor volume was observed between the GC and GC + probiotics groups at week 2 of treatment. Additionally, decreased recruitment of cancer-associated fibroblasts and regulatory T cells, and activation of CD8+ T cells and dendritic cells were observed in the tumor microenvironment. Our findings reveal the positive effects of a probiotics mixture of Lactobacillus and Bifidobacterium in enhancing anti-tumor effects through the gut-tumor immune response axis. Future clinical trials are needed to evaluate the full benefits of this novel supplement with oral probiotics in patients with advanced urothelial carcinoma.

Abstract 2060: Treatment combination strategies to improve radiation efficacy in immunologically cold tumors in vivo

Abstract Introduction: Radiation therapy (RT) is a promising bladder-sparing therapy in muscle-invasive bladder cancer (MIBC). However, 30% of patients exhibit radioresistant tumors requiring salvage surgery. Combining RT with immune checkpoint inhibitor was reported to have synergic effects on anti-tumor immunity. Yet, it is also met with treatment resistance. In addition, activation of the STING pathway was shown to induce cell death, cancer cell antigens release and presentation, and promote the priming, activation and trafficking of T cells into tumors. Previous in vivo results from our team using the MB49 murine bladder cancer cell line - and immunologically ‘hot’ tumor model - demonstrated significant improvement of survival and immune cell infiltration upon STING agonist treatment, when combined with RT and anti-PDL1 treatment. Oppositely, treating the ‘cold’ tumor model UPPL with a combination of RT and anti-PDL1 treatment did not improve survival compared to RT alone. Consistently, UPPL tumors present low T cell and high neutrophil infiltration in vivo. Thus, the main objective of the present study is to evaluate whether combining RT, anti-PDL-1 and STING agonist treatments can improve the immunogenicity of UPPL tumors. Methods: Seven-week-old male C57BL/6 mice were subcutaneously injected with 5.106 UPPL tumor cells. Once tumors reached 0.1-0.15 cm3, mice were randomized into the following treatment groups : 1) Untreated; 2) PDL-1; 3) STING; 4) PDL-1 + STING; 5) RT; 6) RT + PDL-1; 7) RT + STING; 8) RT + STING + PDL-1. Midpoint (~0.6-0.8 cm3, n=5) and endpoint (2 cm3, n=8) tumors, spleens and draining lymph nodes (dLN) were harvested and dissociated for flow cytometry analysis of TME composition and cytokine production. Results: We report that RT and RT-combined treatments delayed tumor growth and prolonged survival in vivo compared to untreated. Additionally, our combination approaches shifted immune infiltration : compared to untreated, each strategy changed myeloid and T cells infiltrating cells in tumors. Combination of RT with anti-PDL-1 and STING agonist favored macrophages infiltration as well as increased MHC-II expression in dendritic cells (DC). Furthermore, we observed increased infiltration of cytotoxic CD8+ T cells (Granzyme B+ and IFN-γ+ CD8+) in these groups. Conclusions: Our results suggest RT and RT combination treatments in cold tumor affect antigen presentation potency in DCs, fine-tune the functionality of infiltrating CD8+ T cells. This preliminary study shows immunologically cold tumors can be modulated through treatment combination, which has relevance in human treatment-resistant tumors. It adds to the very small body of literature taking a deep dive into the immune modulation of a conventionally used ‘cold’ tumor cell line. Citation Format: Eva Michaud, Gautier Marcq, Sabina Fehric, JiaMin Huang, Jose Joao Mansure, Ciriaco Piccirillo, Wassim Kassouf. Treatment combination strategies to improve radiation efficacy in immunologically cold tumors in vivo [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 2060.

Abstract 2524: Investigating the role of neutrophils in muscle-invasive bladder cancer and response to radiation therapy

Abstract Background: Radiation therapy (RT) is an increasingly used bladder-sparing therapy for patients with muscle-invasive bladder cancer (MIBC). However, 20-30% of patients do not respond to RT. Neutrophils have previously been linked to radioresistance, but the specific mechanism is still unknown. Previous work by our team has shown that neutrophil extracellular trap (NET) formation plays a role in RT resistance in an immunologically hot tumor, with high T cell infiltration, using the MB49 murine bladder cancer cell line, in a vivo model. In MIBC, a recently developed cell line can be used to study cold, luminal-like tumors. However, work on this cell line and its response to RT is still in its initial stages. Immune checkpoint inhibitors such as anti-PD-L1 have been tested by our team in these cold tumors of MIBC and have not shown to be effective in treating or radiosensitizing the tumor. Consequently, we aim to determine how neutrophil migration and neutrophil extracellular traps (NET) impact tumor growth in a cold, luminal-like tumor model. Furthermore, we aim to understand how neutrophil migration and NETs impact immunological changes in the tumor microenvironment (TME). Methods: To determine the response to RT in these cold tumors, mice were injected with 5M cells on the right flank of our luminal-like cancer model (UPPL cell line). Once tumors reached 0.1-0.15 cm3, mice were randomized into the different treatment groups: 1) Control; 2) RT; 3) Anti-PDL1 4) DNAse I; 5) RT + Anti-PDL1; 6) RT + DNAse I; 7) Anti-PDL1 + DNAse I; 8) RT + Anti-PDL1 + DNAse I. Size of the tumor was monitored. 8 mice tumors per group were collected at the primary endpoint set at 1.5 cm3 and 5 mice tumors per group were collected after 21 days (midpoint). Tumors were collected analyzed by flow cytometry and immunohistochemistry (IHC). Preliminary Results: Prolonged survival was observed in the mice treated with the triple combination when compared to the other groups. Tumor growth in this group also showed delay early on. So far, the frequency of pro-tumorigenic neutrophils infiltration in tumors seems to happen early on (midpoints) in mice treated with RT, whereas the infiltration happens later (endpoint) in the mice treated with the triple combination. Currently, we are also evaluating the NET production in these tumors through IHC. Conclusion: This ongoing experiment using RT on the UPPL cell line will allow us to understand what happens in patients who are resistant to RT. Understanding the role of neutrophils and NETs, along with the changes in the TME caused by the manipulation of these is key to understanding radiation resistance. This knowledge will bring us one step closer to developing new bladder-sparring treatments and improving patient care in the clinic. Citation Format: Sabina Fehric, Eva Michaud, Surashri Shinde-Jadhav, JiaMin Huang, Jose J. Mansure, Roni Rayes, Jonathan Spicer, Wassim Kassouf. Investigating the role of neutrophils in muscle-invasive bladder cancer and response to radiation therapy [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 2524.

Enhanced anti-tumor immunity of vaccine combined with anti-PD-1 antibody in a murine bladder cancer model.

Programmed cell death protein 1 (PD-1) and ligand programmed death ligand 1 (PD-L1) are important immune-suppressive regulators in the tumor microenvironment. A vaccine-induced immune effect on tumor cells is blunted by the immunosuppressive tumor microenvironment. Therefore, we hypothesized that a dendritic cell (DC) vaccine combined with anti-PD-1 (αPD-1) antibodies could elicit a synergistic anti-tumor immunity in bladder cancer. We produced a model of subcutaneous transplantation in C3H/HeJ mice by transplanting murine MBT-2 bladder cancer cells. DCs were isolated from normal C3H/HeJ mice, followed by stimulation against MBT-2 lysate before injection. Two weeks later of MBT-2 inoculation, αPD-1 and stimulated DCs were injected two times at one-week interval intraperitoneally and intravenously, respectively. Tumor-infiltrating immune cells and splenocytes were analyzed using flow cytometry. T-cell-mediated anti-tumor responses were measured by interferon (IFN)-γ ELISPOT and lactate dehydrogenase assays. The mice treated with DC+αPD-1 showed a significant decrease in tumor volume compared to the DC-treated mice and IgG-treated group. Survival of the DC+αPD-1-treated group was improved compared with that of the IgG-treated mice. IFN-γ secretion from splenocytes against tumor cells was significantly increased in the DC+αPD-1 group compared with that of αPD-1-treated mice. The frequency of CD8+ and CD4+ T-cells in spleens was statistically increased in the DC+αPD-1-treated mice compared to those receiving monotherapy (DC- or αPD-1-treated group). Our results support the hypothesis that the combination therapy of a DC vaccine and αPD-1 antibodies could enhance the anti-tumor immune response against bladder cancer.

Intravesical High Dose BCG Tokyo and Low Dose BCG Tokyo with GMCSF+IFN α Induce Systemic Immunity in a Murine Orthotopic Bladder Cancer Model.

This study evaluates a short therapy schedule for bladder cancer using BCG Tokyo. BCG Tokyo was evaluated in vitro using bone marrow derived dendritic cells, neutrophils, RAW macrophages and the murine bladder cancer cell line, MB49PSA, and compared to other BCG strains. BCG Tokyo > BCG TICE at inducing cytokine production. In vivo, high dose (1 × 107 colony forming units (cfu)) and low dose (1 × 106 cfu) BCG Tokyo with and without cytokine genes (GMCSF + IFNα) were evaluated in C57BL/6J mice (n = 12–16 per group) with orthotopically implanted MB49PSA cells. Mice were treated with four instillations of cytokine gene therapy and BCG therapy. Both high dose BCG alone and low dose BCG combined with cytokine gene therapy were similarly effective. In the second part the responsive groups, mice (n = 27) were monitored by urinary PSA analysis for a further 7 weeks after therapy cessation. More mice were cured at day 84 than at day 42 confirming activation of the immune system. Cured mice resisted the re-challenge with subcutaneous tumors unlike naïve, age matched mice. Antigen specific T cells recognizing BCG, HY and PSA were identified. Thus, fewer intravesical instillations, with high dose BCG Tokyo or low dose BCG Tokyo with GMCSF + IFNα gene therapy, can induce effective systemic immunity.

Animal Models in Bladder Cancer.

Background: Bladder cancer (urothelial cancer of the bladder) is the most common malignancy affecting the urinary system with an increasing incidence and mortality. Mouse models of bladder cancer should possess a high value of reproducibility, predictability, and translatability to allow mechanistic, chemo-preventive, and therapeutic studies that can be furthered into human clinical trials. Objectives: To provide an overview and resources on the origin, molecular and pathological characteristics of commonly used animal models in bladder cancer. Methods: A PubMed and Web of Science search was performed for relevant articles published between 1980 and 2021 using words such as: “bladder” and/or “urothelial carcinoma” and animal models. Animal models of bladder cancer can be categorized as autochthonous (spontaneous) and non-autochthonous (transplantable). The first are either chemically induced models or genetically engineered models. The transplantable models can be further subclassified as syngeneic (murine bladder cancer cells implanted into immunocompetent or transgenic mice) and xenografts (human bladder cancer cells implanted into immune-deficient mice). These models can be further divided—based on the site of the tumor—as orthotopic (tumor growth occurs within the bladder) and heterotopic (tumor growth occurs outside of the bladder).

Antitumor Effect of IL-2 and TRAIL Proteins Expressed by Recombinant Salmonella in Murine Bladder Cancer Cells.

Cancer is the second most deadly disease in the world. The bladder cancer is one of the most aggressive types and shows a continuous increase in the number of cases. The use of bacteria as live vectors to deliver molecules directly to the tumor is a promising tool and has been used as an adjuvant treatment against several types of cancer. The aim of this study was to investigate the antitumor effect of Interleukin 2 (IL-2), TNF-related apoptosis-inducing ligand (TRAIL) and protein MIX against murine bladder cancer cells, lineage MB49. The attenuated Salmonella strain SL3261 was transformed by inserting the IL-2 and TRAIL genes. The effects of proteins on cell viability (MTT method), cell morphology (optical microscopy), cell recovery (clonogenic assay), cell membrane (lactate dehydrogenase release - LDH), on oxidative stress pathway (levels of nitric oxide, NO) and apoptosis (flow cytometry and high resolution epifluorescence images) were evaluated at intervals of 24 and 48 hours of action. The results showed that there was a decrease in cell viability via damage to the cell membrane, alteration of cell morphology, non-recovery of cells, increase in the production of NO and incubate for of cells in the state of apoptosis in the two periods analyzed. The data presented suggest that IL-2, TRAIL and their MIX proteins in MB49 cells have cytotoxic potential and that this is associated with oxidative stress and apoptosis pathways. These results may contribute to the development of new therapeutic strategies for bladder cancer.

Abstract 1516: Inclusion of a Dap10 costimulatory domain enhances anti-tumor efficacy of chimeric PD1-expressing T cells in multiple types of solid tumors

Abstract Adoptive transfer of T cells is a promising anti-tumor therapy for many cancers. To enhance tumor recognition by T cells, chimeric antigen receptors (CAR) consisting of signaling domains fused to receptors that recognize tumor antigens can be expressed in T cells. One receptor that is a prospective target for a new chimeric antigen receptor is PD1 because the ligands for the PD1 receptor are expressed on many cancer types. Therefore, we developed a murine chimeric PD1 receptor (chPD1) consisting of the PD1 receptor extracellular domain and the activation domain of CD3 zeta. In addition, current chimeric antigen receptor therapies utilize various costimulatory domains to enhance anti-tumor efficacy. Therefore, we also compared the inclusion of CD28, Dap10, 4-1BB, GITR, ICOS, or OX40 costimulatory domains in the chPD1 receptor to determine which costimulatory domain induced optimal anti-tumor immunity. To determine if this novel CAR could potentially target a wide variety of tumors, the anti-tumor efficacy of chPD1 T cells against murine lymphoma, melanoma, kidney, pancreatic, liver, colon, breast, ovarian, prostate, and bladder cancer cell lines was measured. Of the eighteen cell lines tested, all expressed PD1 ligands on their cell surface, making them potential targets for chPD1 T cells. Regardless of the costimulatory domain in the CAR, all of the chPD1 T cells induced similar levels of T cell proliferation and tumor cell lysis. However, differences were observed in the cytokine secretion profiles depending on which costimulatory receptor was included in the CAR. While most of the chPD1 T cell receptor combinations secreted both pro-inflammatory (IFNγ, TNFα, IL-2, GM-CSF, IL-17, and IL-21) and anti-inflammatory cytokines (IL-10), chPD1 T cells containing a Dap10 costimulatory domain secreted high levels of proinflammatory cytokines but did not secrete a significant amount of anti-inflammatory cytokines. Furthermore, T cells expressing chPD1 receptors with a Dap10 domain also had the strongest anti-tumor efficacy in vivo. ChPD1 T cells did not survive for longer than 14 days in vivo, however treatment with chPD1 T cells induced long-lived protective host-anti-tumor immune responses in tumor-bearing mice. Therefore, adoptive transfer of chPD1 T cells could be a novel therapeutic strategy to treat multiple types of cancer and inclusion of the Dap10 costimulatory domain in chimeric antigen receptors may induce a preferential cytokine profile for anti-tumor therapies. Citation Format: Amorette E. Barber. Inclusion of a Dap10 costimulatory domain enhances anti-tumor efficacy of chimeric PD1-expressing T cells in multiple types of solid tumors [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 1516.

Bladder tumor metabolic alterations in response to IFNα gene therapy.

468 Background: Intravesical interferon-alpha (IFNα) gene therapy with Nadofaragene firadenovec has shown clinical efficacy in patients with non-muscle invasive bladder cancer (NMIBC) in a phase III clinical trial, highlighting the therapeutic potential of this approach in a disease with significant unmet clinical need. Optimizing the clinical efficacy of IFNα gene therapy requires an understanding of the underlying therapeutic mechanisms. Here, we investigate the impact of IFNα gene therapy on tumor metabolism using in vitro and orthotopic murine preclinical models and clinical trial data to elucidate mechanisms of tumor resistance and identify predictive biomarkers. Methods: In vitro murine bladder cancer cell lines treated with recombinant IFNα (rIFNα) and lentiviral IFNα (LV-IFNα) were analyzed by whole-transcriptome sequencing, glucose uptake, and lactate production. Preclinical murine bladder cancer models were treated with LV-IFNα (orthotopic tumor model) or Poly(I:C) (flank tumor model), a potent IFN inducer. Disease response was monitored by in vivo real-time luciferase imaging. Tumors were harvested and whole-transcriptome sequencing performed to assess effects of IFNα therapy on tumor metabolism and lipidomics. Lipidomic profiling was performed on patient urine samples from a phase II clinical trial of intravesical Nadofaragene firadenovec (7 clinical responders and 6 non-responders) to assess for clinically-relevant differences in lipid metabolism. Results: Following IFNα therapy in vitro and in murine orthotopic bladder cancer models, we identified downregulation of genes involved in fatty acid synthesis and upregulation of genes involved in glycolysis by whole-transcriptome sequencing. This was confirmed by higher glucose uptake and lactate production by IFNα-treated cells in vitro. These findings were recapitulated in whole-transcriptome sequencing data of human bladder tumors treated with intravesical Nadofaragene firadenovec. Lipidomics performed on murine MB49 tumors treated with poly(I:C) identified 79 upregulated lipids, including phosphotidyl choline, spingomyelin and phosphatidyl ethanolamine, and 12 downregulated lipids, notably the cardiolipin class. Lipidomics performed on patient urine samples collected pre- and post-treatment with intravesical Nadofaragene firadenovec detected >592 lipids with distinct expression profiles differentiating clinical responders and non-responders at both timepoints. Conclusions: We describe novel modulation of glucose and lipid metabolism by bladder tumor cells in response to IFNα gene therapy. These metabolic changes were reproducible across in vitro, in vivo and clinical trial studies and improve our mechanistic understanding of IFNα gene therapy, identify tumor escape pathways targetable with combination therapy regimens, and identify a new class of biomarkers for predicting clinical response of NMIBC to IFNα gene therapy.

Optimizing Sequence of PD-L1 Immune-Checkpoint Inhibitors and Radiation Therapy in Bladder Cancer

BACKGROUND: New bladder preserving strategies are needed for muscle invasive bladder cancer (MIBC). Combined therapy of immune-checkpoint inhibitors and radiation was shown to have synergistic antitumoral effects in preclinical studies. OBJECTIVES: We aim to evaluate whether the sequence of administration of this combined therapy impacts antitumoral response. METHODS: We developed an in-vivo syngeneic MIBC mouse model where murine bladder cancer cells (MB49) were injected subcutaneously in the right flank of C57BL/6 mice. Mice were then randomized to the following treatments: control, anti-programmed cell death ligand 1 (PD-L1) alone, radiation alone (XRT) consisting of 6.25 Gy x2 fractions, concurrent anti-PD-L1 with XRT, neoadjuvant anti-PD-L1 followed by XRT, or XRT followed by adjuvant anti-PD-L1 therapy. Tumor growth, survival, and rate of response were analyzed. RESULTS: Total of 60 mice were randomized. One-way analysis of variance showed statistically significant difference in tumor growth rate across the treatment arms (p = 0.029). Importantly, timing of immunotherapy (neoadjuvant, concurrent, or adjuvant) did not alter either tumor growth or survival (p > 0.05). The rate of response was also similar in each combination arm (p > 0.05). CONCLUSION: Combining anti-PD-L1 immunotherapy and radiation therapy offers optimal antitumoral responses. Timing of immunotherapy (neoadjuvant, concurrent, or adjuvant) does not appear to affect outcomes. Whether the toxicity profile differs across various sequential deliveries of combination therapy requires further evaluation.

Relevance of iNOS expression in tumor growth and maintenance of cancer stem cells in a bladder cancer model.

The expression of inducible nitric oxide (NO) synthase (iNOS) in human bladder cancer (BC) is a poor prognostic factor associated with invasion and tumor recurrence. Here, we evaluated the relevance of iNOS expression in BC progression and in cancer stem cell (CSC) maintenance in a murine BC model. Also, iNOS expression and CSC markers were analyzed in human BC samples. iNOS inhibitors (L-NAME or 1400W) or shRNA were used on murine BC model with different iNOS expressions and invasiveness grades: MB49 (iNOS+, non-muscle invasive (NMI)) and MB49-I (iNOS++, muscle invasive (MI)), in order to analyzed cell proliferation, tumor growth, angiogenesis, number of CSC, and pluripotential marker expression. iNOS, SOX2, Oct4, and Nanog expressions were also analyzed in human BC samples by qPCR and immunohistochemistry. iNOS inhibtion reduced parameters associated with tumor progression and reduced the number of CSC, wich resulted higher in MB49-I than in MB49, in concordance with the higher expression of SOX2, Oct4, and Nanog. The expression of SOX2 was notoriously diminished, when iNOS was inhibited only in the MI cell line. Similar results were observed in human samples, where MI tumors expressed higher levels of iNOS and pluripotential genes, in comparison to NMI tumors with a positive correlation between those and iNOS, suggesting that iNOS expression is associated with CSC. iNOS plays an important role in BC progression and CSC maintenance. Its inhibition could be a potential therapeutic target to eradicate CSC, responsible fortumor recurrences. KEY MESSAGES: • iNOS expression is involved in bladder tumor development, growth, and angiogenesis. • iNOS expression is involved in bladder cancer stem cell generation and maintenance, playing an important role regulating their self-renewal capacity, especially in muscle invasive murine bladder cancer cells. • iNOS expression is higher in human muscle invasive tumors, in association with a high expression of pluripotential genes, especially of SOX2.

Abstract 5553: The effect of PLAG on the PD-L1 immune-checkpoint drug therapy in the MB49 bladder cancer syngeneic model

Abstract Background: The development of immune-checkpoint drugs, a fourth-generation anticancer drug, is a significant breakthrough in anticancer research. Cancer therapy using immune-checkpoint drugs are still enlarged. To improve the efficacy of immune-checkpoint drugs, modulation of the tumor microenvironment is essentially required. In this experiment, we examined the elevated anti-cancer efficacy of 1-Palmitoyl-2-Linoleoyl-3-Acetyl-rac-Glycerol (PLAG), which has been demonstrated to attenuate tumor infiltrated neutrophils (TINs) in the tumor, along with the PD-L1 immune checkpoint inhibitor treatment. Methods: The syngeneic model was used (n=6) to investigate the enhanced anti-tumor effect of PD-L1 antibody with the addition of PLAG. MB49 murine bladder cancer cells were implanted into the C57BL/6 mice subcutaneously and bred for 5 weeks. After a week from tumor implantation, PLAG at different dosages (25/50/100 mpk) were daily administered orally for another 4 weeks with or without 5 mpk PD-L1 antibody (10F.9G2). PD-L1 antibody was delivered via IP injection twice a week. Tumor growth was calculated in 3-day intervals. Neutrophil chemotaxis-related chemokines and neutrophil-to-lymphocyte rate (NLR) were also evaluated with a 2-week interval. The degree of neutrophil infiltration in the tumor on the day of sacrifice and the degree of infiltration between lymphocytes and neutrophils were analyzed. Results: The PLAG treatment groups demonstrated that the tumor burden decreased in a concentration-dependent manner. In 50 and 100 mpk of PLAG treated mice, the tumor burden was decreased to a significant value compared to a positive control (p < 0.05). In the group treated with PD-L1 antibody alone, the growth rate of the tumor decreased until about 2 weeks. In the group treated simultaneously with PLAG and PD-L1 antibody, the growth of the tumor was significantly reduced compared to the group treated with PD-L1 antibody alone. As a result of calculating neutrophils and lymphocytes every two weeks, NLR level in the group treated with PLAG and PD-L1 was significantly decreased compared to that treated with PD-L1 antibody alone. Besides, the number of TINs were effectively reduced by PLAG treatment alone. The interruption of tumor growth and reduced chemokine secretion were also observed in the PLAG treated groups. In summary, our data suggest that PLAG provides an enhanced PD-L1 antibody effect on the regression of tumor burden in the syngeneic mice model via reducing the number of TINs. Conclusion: PLAG may be utilized for improving the efficacy of PD-L1 antibody on reducing the tumor burden at the devastating tumor microenvironment. Citation Format: Guen Tae Kim, Sun Young Yoon, Ji Sun Park, Ki-Young Sohn, Jae Wha Kim. The effect of PLAG on the PD-L1 immune-checkpoint drug therapy in the MB49 bladder cancer syngeneic model [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5553.

Abstract A12: Bladder cancer-derived extracellular vesicles and immune activation

Abstract Background: Bladder tumors occur on the luminal surface of the bladder, and cancer cells and cellular components are shed in urine, which permits the isolation of an enriched population of bladder cancer-specific extracellular vesicles (EVs). EVs contain proteins, miRNA, mRNA, and cellular metabolites, which may serve as stimulators of immune cells. The objective of this study was to evaluate the immune potential of tumor-derived EVs (TEVs) produced on exposure to BCG using a murine bladder cancer cell line and immune cells. Methods: TEVs were isolated by differential high-speed centrifugation of cell culture supernatants. They were confirmed to be extracellular vesicles by electron microscopy and size measurement using nanoparticle tracking analysis. Unstimulated murine bladder cancer cells (MB49) were used to prepare TEV1. The cells were then exposed to BCG Tokyo (MOI 4) and TEVs were isolated after 2 hours (TEV2). BCG was then washed off and the cells were allowed to grow in complete media for 2 days before isolation of the third sample, TEV3. EVs from BCG (BEV) were collected to serve as a control. Bone marrow-derived cells were obtained from C57BL/6J mice to generate dendritic cells (DC) and neutrophils. These cells were untreated or treated with 1ug of TEVs or BEV or BCG (MOI 5) for 24 hours. The supernatants were analyzed for cytokine production and the DCs and neutrophils were analyzed for activation markers by flow cytometry. The institutional animal care and use committee approved the use of mice. Results: DCs treated with TEV2 had significantly higher expression of CD86 (at similar levels when DCs were treated with BCG) and MHC2, both of which enhanced the DC's capacity to present antigens to T cells, when compared to TEV1 or TEV3. While neutrophils induced by BCG expressed significantly higher levels of costimulatory molecules CD80, CD83, CD86, and MHC2, TEV2 induced significant expression of CD80 and CD86. BCG caused a massive release of proinflammatory cytokines (IL6, TNFa, and IL12p70) and the anti-inflammatory cytokine IL10. Cytokine production induced by TEV2 was not as high as that induced by direct BCG stimulation, but it was significantly higher than that produced by untreated cells or TEV1 and TEV3. Unlike BCG, TEV2 did not significantly stimulate IL10 production. Conclusion: Our results demonstrate that tumor cells treated with BCG for 2 hours produce EVs that are able to cause significant modulation of DCs and neutrophils. TEVs generated during BCG immunotherapy have immunostimulatory potential. Therefore, TEVs represent a promising source of material to increase immune activation and efficacy of BCG therapy. This could reduce the number of instillations and adverse effects associated with BCG therapy. Citation Format: Sin Mun Tham, Kesavan Esuvaranathan, Ratha Mahendran. Bladder cancer-derived extracellular vesicles and immune activation [abstract]. In: Proceedings of the AACR Special Conference on Bladder Cancer: Transforming the Field; 2019 May 18-21; Denver, CO. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(15_Suppl):Abstract nr A12.

Abstract A01: Adoptive cell therapy (ACT) using tumor-infiltrating lymphocytes (TIL) for the treatment of bladder cancer

Abstract Bladder cancer remains a leading cause of death and one of the most expensive cancers to treat in the United States. Adoptive cell therapy (ACT) using tumor-infiltrating lymphocytes (TIL) is a personalized therapeutic approach that has the potential to treat bladder cancer at every stage of disease. We have previously demonstrated the ability to expand tumor reactive T cells from transurethral resection, radical cystectomy, and metastatic lymph node tumor specimens collected from bladder cancer patients. In this study, our goal is to investigate different delivery approaches of ACT in vivo to determine the best strategy to decrease tumor burden and advise clinical trial design. Experiments were performed using MB49 murine bladder cancer cells transfected to express ovalbumin (MB49OVA). MB49OVA cells are recognized by OVA-specific OT-I T cells as determined by IFN-gamma production in vitro. Our methods include both subcutaneous and orthotopic bladder tumor models. In vivo, we first tested systemic delivery of OT-I T cells (5.0 × 10e6) by tail vein injection after lymphodepletion with a regimen of cyclophosphamide followed by fludarabine in mice bearing subcutaneous MB49OVA tumors. ACT-treated mice experienced significant tumor regression (p=0.02), improved survival (median survival PBS=47 days, ACT=undefined, p=0.01), and increased tumor infiltration of CD3+, CD4+, and CD8+ T cells. OT-I T cells as well as endogenous OVA-specific CD8+ T cells were detectable in the spleens and tumors of treated mice. Next we tested the efficacy of intravesical delivery of OT-I T cells in mice bearing orthotopic MB49OVA tumors, without prior lymphodepletion. OT-I T cells (4.0 × 10e6) were delivered directly to the bladder via catherization and tumor growth was monitored weekly via ultrasound imaging. Infiltration of CellTrace Violet-labeled OT-I T cells into orthotopic tumors was detected after 3 hours of incubation by flow cytometry analysis of resected tumor. Orthotopic bladder tumor growth was significantly abrogated in ACT-treated mice compared with PBS control-treated mice (p=0.001) and improved survival was observed (median survival PBS=35 days, ACT=undefined). An increase in CD8+ T-cell infiltration was measured in tumors of mice at day 60 post treatment. In order to evaluate the efficacy of TIL transfer in these bladder tumor models, T cells infiltrating subcutaneous MB49OVA tumors were isolated and cultured in vitro in media containing IL-2. After 1 week, bladder TIL demonstrated reactivity against MB49OVA and MB49 parental cells as determined by IFN-gamma production. Future work will implement the adoptive transfer of MB49 TIL for the treatment of orthotopic bladder tumors alone or in combination with anti-PD-L1 therapy. Taken together, these data suggest that ACT using bladder tumor-specific T cells has the potential to reduce bladder tumor burden when given either systemically or intravesically directly into the bladder. Citation Format: Brittany L. Bunch, Jennifer Morse, Sarah Asby, Michael Poch, Shari Pilon-Thomas. Adoptive cell therapy (ACT) using tumor-infiltrating lymphocytes (TIL) for the treatment of bladder cancer [abstract]. In: Proceedings of the AACR Special Conference on Bladder Cancer: Transforming the Field; 2019 May 18-21; Denver, CO. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(15_Suppl):Abstract nr A01.

Abstract A17: Gene expression changes associated with metastasis in mice with bladder cancer

Abstract Background: Prognosis for bladder cancer is dependent on both tumor stage and grade. In patients with non-muscle invasive bladder cancer, the tumor invariably recurs and may progress. Patients who subsequently develop metastatic disease or present with it have a worse prognosis. The purpose of this study was to detect and find differences in patterns of gene expression between the primary tumor and common metastatic sites in a mouse model of bladder cancer to identify possible triggering events that result in metastasis. Methods: Five- to six-week-old female C57BL/6 mice were orthotopically implanted with MB49-PSA (murine bladder cancer cells secreting human prostate-specific antigen as a tumor marker). The institutional animal care and use committee approved the use of mice. At termination (up to 78 days after tumor implantation), bladders, kidneys, lymph nodes, and lungs were snap frozen and RNA was extracted by homogenizing the tissue in Trizol. Tumor presence in the tissues was confirmed by PSA gene expression, which was quantified by real-time PCR. Gene expression level profiling of the transcriptome was analyzed via RNA sequencing of samples from 4 bladders, 4 kidneys, 3 lymph nodes, and 2 lungs. Gene expression of a select group of genes was verified by real-time PCR with a bigger population of RNA samples. Results: Common differentially expressed genes were found between bladder and kidney (42 genes), bladder and lung (54 genes), and bladder and lymph nodes (198 genes). Bioinformatics software Panther and String were used to assign the genes into 6 pathways. These were morphogenesis of a branching epithelium; positive regulation of transcription from RNA polymerase II promoter; cell differentiation; negative regulation of epithelial to mesenchymal transition; epithelial cell differentiation; and transcriptional mis-regulation in cancer. Expression of paired-box 8 (Pax8), a transcription factor involved in embryonic development, was significantly higher in the kidneys compared to the other tissues. This suggests that overexpression of Pax8 may facilitate malignant development but may not be required for later stages of cell differentiation. Nanog, also a transcription regulator, was significantly higher in the kidneys when compared to bladders and was elevated in the lungs as well. It promotes epithelial-mesenchymal transition, resulting in metastasis; thus, increased expression of Nanog in cancer cells may indicate tumor aggressiveness. In the literature, Pax8 is expressed in noninvasive bladder tumors but not in normal bladder tissue in humans and Nanog expression is high in bladder tumors. Conclusion: Pax8 and Nanog expression indicates that the murine model of bladder cancer with metastatic disease is similar to that observed in patients. Thus, this model could be used to evaluate methods of blocking progression. Citation Format: Sin Mun Tham, Stefanie Alicia Fung, Kesavan Esuvaranathan, Ratha Mahendran. Gene expression changes associated with metastasis in mice with bladder cancer [abstract]. In: Proceedings of the AACR Special Conference on Bladder Cancer: Transforming the Field; 2019 May 18-21; Denver, CO. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(15_Suppl):Abstract nr A17.

Analysis of chemotherapy-related modulation of the immune microenvironment in muscle invasive bladder cancer.

5049 Background: Novel immune checkpoint inhibitors provide significant clinical benefits for patients with metastatic bladder cancer. It is known that chemotherapy administered to muscle invasive patients prior to radical cystectomy (neoadjuvant chemotherapy) improves survival. However, it is unknown whether immune checkpoint inhibitor therapy in combination with chemotherapy can provide further clinical benefits as neoadjuvant therapy. Here, we test the hypothesis that treatment of bladder cancer with certain chemotherapy agents can modulate bladder tumor immune microenvironment (TIME) for optimal combination with immune checkpoint therapy. Methods: Time course and dose response experiments were performed using eight human bladder cancer cell lines (UMUC3, RT4, 253J, RT112, J82, HT1376, T24, and HT1197) and two murine bladder cancer cell lines (MB49, MBT2). Conventional chemotherapy agents and combinations (MVAC, GemCis, PemVin) were used to treat bladder cancer cell lines. Flow cytometry analysis was used to measure immune cell subsets and PD-L1 expression. For in vivo studies, the subcutaneous MB49 murine bladder cancer model was used to evaluate responses to chemotherapy and anti-PD-L1 combinations. Pre- and post-treatment bladder tumors from patients who received neoadjuvant MVAC and GemCis are selected to evaluate changes in TIME. Results: Our data demonstrate that chemotherapy agents varies in their ability to up-regulate PD-L1 expression on bladder cancer cell lines. Vinblastine, gemcitabine, and pemetrexed treatment each resulted in significant upregulation of PD-L1 expression. Combination regimens with GemCis or PemVin demonstrated induction of PD-L1 across different cell lines. In in-vivo studies, GemCis + anti-PD-L1 had a synergistic activity in causing tumor regression. We also found that sequential versus concurrent treatment with chemotherapy and anti-PD-L1 had a similar outcome. Tissue analyses show that combination chemotherapies increased CD4 Th cell infiltration while decreasing Treg cells in TIME. Consistent with the in vitro data, PD-L1 expression was also up-regulated with combination treatment. The evaluation of TIME modulation in human bladder tumors treated with neoadjuvant MVAC or GemCis is ongoing. Conclusions: Our data suggest that chemotherapy could favorably modulate TIME and thus, may be combined with immune checkpoint inhibitor to improve anti-tumor responses in the neoadjuvant setting for patients with muscle invasive bladder cancer.

Biomolecular study and conjugation of two para-aminobenzoic acid derivatives with serum proteins: drug binding efficacy and protein structural analysis

Two aminobenzoic acid derivatives DAB-0 and DAB-1 showed distinct biological properties on murine bladder cancer (BCa) cell line MB49-I. In contrast to DAB-1, DAB-0 does not possess any anti-inflammatory activity and is less toxic. Furthermore, DAB-0 does not interfere with INFγ-induced STAT1 activation and TNFα-induced IκB phosphorylation, while DAB-1 does. In order to rationalize these results, the binding efficacy of DAB-0 and DAB-1 with serum proteins such a human serum albumin (HSA), bovine serum albumin (BSA) and beta-lactoglobulin (β-LG) was investigated in aqueous solution at physiological pH. Multiple spectroscopic methods and thermodynamic analysis were used to determine the binding efficacy of DAB-0 and DAB-1 with serum proteins. Drug-protein conjugation was observed via through ionic contacts. DAB-1 forms stronger adducts than DAB-0, while β-LG shows more affinity with the order of stability β-LG > BSA > HSA. The stronger complexation of DAB-1 with serum proteins might account for its biological potential and transport in the blood. The binding efficacy ranged from 40 to 60%. Major alterations of protein secondary structures were detected upon drug complexation. Serum proteins are capable of delivering DAB-1 in vitro.Communicated by Ramaswamy H. Sarma