Anti-murine Antibody Research Articles

UPAR Immuno-PET in Pancreatic Cancer, Aging, and Chemotherapy-Induced Senescence.

Identifying cancer therapy resistance is a key time-saving tool for physicians. Part of chemotherapy resistance includes senescence, a persistent state without cell division or cell death. Chemically inducing senescence with the combination of trametinib and palbociclib (TP) yields several tumorigenic and prometastatic factors in pancreatic cancer models with many potential antibody-based targets. In particular, urokinase plasminogen activator receptor (uPAR) has been shown to be a membrane-bound marker of senescence in addition to an oncology target. Methods: Here, 2 antibodies against murine uPAR and human uPAR were developed as immuno-PET agents to noninvasively track uPAR antigen abundance. Results: TP treatment increased cell uptake both in murine KPC cells and in human MiaPaCa2 cells. In vivo, subcutaneously implanted murine KPC tumors had high tumor uptake with the antimurine uPAR antibody independently of TP in young mice, yet uPAR uptake was maintained in aged mice on TP. Mice xenografted with human MiaPaCa2 tumors showed a significant increase in tumor uptake on TP therapy when imaged with the antihuman uPAR antibody. Imaging with either uPAR antibody was found to be more tumor-selective than imaging with [18F]FDG or [18F]F-DPA-714. Conclusion: The use of radiolabeled uPAR-targeting antibodies provides a new antibody-based PET imaging candidate for pancreatic cancer imaging as well as chemotherapy-induced senescence.

Administration of an antibody against apoptosis inhibitor of macrophage prevents aortic aneurysm progression in mice

Apoptosis inhibitor of macrophage (AIM) is known to induce apoptosis resistance in macrophages and to exacerbate chronic inflammation, leading to arteriosclerosis. The role of AIM in aortic aneurysm (AA) remains unknown. This study examined the effects of an anti-AIM antibody in preventing AA formation and progression. In apolipoprotein E-deficient mice, AA was induced by subcutaneous angiotensin II infusion. Mice were randomly divided into two groups: (i) AIM group; weekly anti-murine AIM monoclonal antibody injection (n = 10), and (ii) IgG group; anti-murine IgG antibody injection as control (n = 14). The AIM group, compared with the IgG group, exhibited reduced AA enlargement (aortic diameter at 4 weeks: 2.1 vs. 2.7 mm, respectively, p = 0.012); decreased loss of elastic lamellae construction; reduced expression levels of IL-6, TNF-α, and MCP-1; decreased numbers of AIM-positive cells and inflammatory M1 macrophages (AIM: 1.4 vs. 8.0%, respectively, p = 0.004; M1 macrophages: 24.5 vs. 55.7%, respectively, p = 0.017); and higher expression of caspase-3 in the aortic wall (22.8 vs. 10.5%, respectively, p = 0.019). Our results suggest that administration of an anti-AIM antibody mitigated AA progression by alleviating inflammation and promoting M1 macrophage apoptosis.

Advances of monoclonal antibodies and analysis of marketed antibody drugs

In recent years, there has been a frequent occurrence of various epidemics worldwide such as COVID-19, monkeypox, influenza, and others additionally, there has been an increase in the number of new patients diagnosed with various types of tumors. Traditional drugs have limited effectiveness against emerging infectious diseases, tumors, and autoimmune diseases. However, with the emergence of hybridoma technology, monoclonal antibodies have achieved extensive applications and antibody drugs are playing an important role in modern medicine. Monoclonal antibodies have undergone various development stages, starting from mouse-derived antibodies to human-mouse chimeric antibodies, humanized antibodies, and ultimately human antibodies. Throughout this process, their immunogenicity has gradually decreased, while their safety for human use steadily increased. Fully human antibodies are currently the safest form of antibody, because their sequences all come from human sources and they do not induce human anti-murine antibody reactions. With the advance of genetic engineering technology, flow cytometry coupled to single B cell gene amplification technology has made it easier to construct and screen for fully human monoclonal antibodies. The development of antibody drugs has provided new opportunities, and the market for monoclonal antibody drugs will further expand. This article reviews the research progress of monoclonal antibodies and presents information on the 163 monoclonal antibody drugs approved by the United States Food and Drug Administration (FDA) as of Oct 1st, 2023. The aim is to offer new insights for the development and production of monoclonal antibodies in China.

Preclinical and translational pharmacology of afucosylated anti-CCR8 antibody for depletion of tumour-infiltrating regulatory T cells.

RO7502175 is an afucosylated antibody designed to eliminate C-C motif chemokine receptor 8 (CCR8)+ Treg cells in the tumour microenvironment through enhanced antibody-dependent cellular cytotoxicity (ADCC). We report findings from preclinical studies characterizing pharmacology, pharmacokinetics (PK)/pharmacodynamics (PD) and safety profile of RO7502175 and discuss the translational PK/PD approach used to inform first-in-human (FiH) dosing strategy and clinical development in solid tumour indications. RO7502175 demonstrated selective ADCC against human CCR8+ Treg cells from dissociated tumours in vitro. In cynomolgus monkeys, RO7502175 exhibited a biphasic concentration-time profile consistent with immunoglobulin G1 (IgG1) antibodies, reduced CCR8+ Treg cells in the blood, induced minimal and transient cytokine secretion, and was well tolerated with a no-observed-adverse-effect level (NOAEL) of 100 mg·kg-1. Moreover, RO7502175 caused minimal cytokine release from peripheral blood mononuclear cells (PBMCs) in vitro. A quantitative model was developed to capture surrogate anti-murine CCR8 antibody PK/PD and tumour dynamics in mice and RO7502175 PK/PD in cynomolgus monkeys. Subsequently, the model was used to project RO7502175 human PK and receptor occupancy (RO) in patients. Because traditional approaches resulted in a low FiH dose for this molecule, even with its superior preclinical safety profile, an integrated approach based on the totality of preclinical data and modelling insights was used for starting dose selection. This work demonstrates a translational research strategy for collecting and utilizing relevant nonclinical data, developing a mechanistic PK/PD model and using a comprehensive approach to inform clinical study design for RO7502175.

Flow cytometric-based detection of CD80 is a useful diagnostic marker of acute myeloid leukemia in dogs.

CD80, a co-stimulatory molecule required for optimal T cell activation, is expressed on antigen-presenting cells, including monocytes and dendritic cells, in dogs and humans. We hypothesized that CD80 would be expressed on tumor cells in dogs from acute myeloid leukemia (AML) but not dogs with lymphoid neoplasms. We first evaluated the cellular staining pattern of a hamster anti-murine CD80 antibody (clone 16-10A1, ThermoFisher Scientific Cat# 17-0801-82, RRID: AB_469417) in blood and bone marrow aspirates from healthy dogs. Using flow cytometric analysis and examination of modified Wright's-stained cytologic smears of unsorted and flow cytometric or immunomagnetic bead-sorted leukocytes, we show that the antibody binds to mature and immature neutrophils and monocytes, but not lymphocytes or eosinophils, in blood and bone marrow. We then added the antibody to routine flow cytometric panels for immunophenotyping hematopoietic neoplasms in dogs. We found that the antibody labeled tumor cells in 72% of 39 dogs with AML and 36% of 11 dogs with acute leukemia expressing lymphoid and myeloid markers ("mixed lineage") but none of the dogs with B (n = 37) or T (n = 35) lymphoid neoplasms. A higher proportion of tumor cells in dogs with AML were labeled with the anti-CD80 antibody vs antibodies against other myeloid-associated antigens, including CD4 (36%, p = 0.003), CD11b (44%), CD11c (46%), CD14 (38%, p = 0.006) and CD18 (59%, clone YFC118). In contrast, antibodies against CD11b and CD11c bound to tumor cells in 8-32% of the lymphoid neoplasms. We show that CD80, as detected by antibody clone 16-10A1, is a sensitive and specific marker for AML and would be useful to include in flow cytometric immunophenotyping panels in dogs.

The Therapeutic Efficacy of CD19 Chimeric Antigen Receptor T Cells in Immune Thrombocytopenia Model

Abstract Introduction: ITP is a hemorrhagic autoimmune disease characterized by excessive platelet destruction and impaired platelet production,resulting in a high risk of bleeding. The pathogenesis of ITP involves immune intolerance towards platelet antigen, with platelet autoantibodies produced by plasma cells playing a significant role. Current treatments targeting this pathogenesis mainly rely on CD20 monoclonal antibodies, such as rituximab. However, as CD20 expression is present at the pre-B cell and mature B cell stages but absent on the surface of mature plasma cells. This can explain why a subset of autoantibody-positive patients do not respond to B-cell depletion therapy. CAR-T cell therapy, a form of adoptive cellular immunotherapy, has shown great potential in hematological malignancies and solid tumors. Recent studies have demonstrated its potential effectiveness of CAR-T cell therapy in various autoimmune diseases. CD19, expressed at all stages of B cell differentiation, presents an opportunity for CAR-T cell therapy in ITP. This study aims to evaluate the efficacy of CD19 CAR-T cell immunotherapy in an active murine ITP model. Methods: CD42-knockout mice were immunized with wild type (WT) C57BL/6 mice and splenocytes from these immunized mice were transplanted into irradiated WT mice to construct a murine model of active ITP. The ITP mice were then randomized into two groups, with the experimental group receiving an intraperitoneal injection with 1×10 6 CD19 CAR-T cells. Platelet counts were monitored weekly, and after 3 weeks, the ITP mice were euthanized and sacrificed. Single-cell suspensions were prepared from harvested spleens for analysis. Anti-murine antibodies were analyzed using flow cytometry (Beckmann Coulter, Brea, CA, USA). All data were analyzed by Statistical Package for the Social Sciences (SPSS) software, version 25.0 (IBM Corp., Armonk, NY, USA). P < 0.05 was considered statistically significance. Results: Our results demonstrated that the platelet counts of ITP mice reached their lowest level on day 7 after spleen cell transplantation, gradually recovering within a week. Platelet counts were significantly higher in the CD19 CAR-T cell therapy group compared to the control group on day 7 and persisted until day 21. There were no significant differences in weight between two groups, indicating no severe complication or CRS were identified. In the third week CD19 CAR-T cell therapy, the proportion of plasma cells in the spleen was determined, showing a marked decrease in the percentage of CD138+ plasma cells in the CAR-T group compared to the control group. Additionally, at day 14, the titers of anti-platelet CD42-specific antibodies were significantly lower in the CAR-T cell treated group compared to the control group. Furthermore, the mean fluorescence intensity (MFI) of CD19+ B cells in the spleen cells of the CD19 CAR-T cell immunotherapy group was significantly decreased compared to the control group. Conclusion: This study demonstrates the effectiveness of CD19 CAR-T cell therapy in treating thrombocytopenia by suppressing plasma and B cells in a mouse model of active ITP. These findings provide valuable insights into the potential therapeutic application of CD19 CAR-T cell immunotherapy for immune thrombocytopenia. Disclosure: No conflict of interest.

Abstract 13322: Administrating the Anti-Apoptosis Inhibitor of Macrophage Antibody Prevents Aortic Aneurysm Progression in Mice

Introduction: Our previous report has shown that macrophages play vital roles in developing aortic aneurysms (AA). Apoptosis inhibitor of macrophage (AIM) secreted from macrophages is known to induce apoptosis resistance of macrophages and exacerbate chronic inflammation, which leads to arteriosclerosis. However, it is unclear the role of AIM in AA. Hypothesis: We hypothesized that administering the anti-AIM antibody could prevent eventual AA progression via inhibiting chronic inflammation and promoting apoptosis of macrophages. Methods: The AA was induced in apolipoprotein E deficient mice by subcutaneous angiotensin II (ATII) infusion. Along with ATII infusion, an anti-murine AIM monoclonal antibody or anti-murine IgG antibody was injected intraperitoneally. Mice were divided randomly into two groups: (i) AIM group; weekly anti-AIM antibody injection (n=10), and (ii) IgG group; anti-IgG antibody injection as control (n=14). All animals were euthanized 4 weeks after study initiation. Results: There were two deaths in the control group and one in the AIM group. None of the deaths were aorta-related. Compared with the IgG group, the AIM group exhibited reduced AA enlargement (aortic diameter at four weeks: AIM 2.1 vs. IgG 2.7 mm, p = 0.012), less loss of construction of the elastic lamellae, reduction protein expression levels of various inflammatory response including IL-6, TNF-α and MCP-1, a decrease in the number of AIM-positive cells and inflammatory M1 macrophages (AIM: 1.4 vs. 8.0 %, p = 0.004, M1 macrophages: 24.5 vs. 55.7 %, p = 0.017), and higher expression of caspase-3 (22.8 vs. 10.5 %, p = 0.019) in the aortic wall. Conclusions: Our results suggested that anti-AIM antibody therapy mitigated AA progression by controlling inflammation and promoting apoptosis.

P111 Efficacy of a novel long-acting lipidated interleukin-22, alone and in combination with anti-TNF treatment, in a murine chronic DSS colitis model

Abstract Background Most current treatments and new agents in clinical development for Inflammatory Bowel Disease focus on inhibition of excessive inflammation. However, to break the ceiling on current clinical remission rates, new approaches, for example targeting mucosal healing, are needed. The cytokine interleukin-22 (IL-22) plays a key role in epithelial healing and has early proof-of-concept as a potential drug class in a phase 1 trial in Ulcerative Colitis. Here we present results from a mouse model of colitis demonstrating the efficacy of IL-22 agonism and complementarity with existing immunomodulatory treatment options. Methods Eight-week-old female C57Bl/6N mice (n=56) were subjected to a DSS-induced model of colitis; mice were given 2% (weight/volume) DSS in the drinking water for three 7-day cycles followed by 7 days of regular drinking water. Mice were treated from day 18 until the end of study with either vehicle, lipidated IL-22, an anti-murine TNF antibody at a suboptimal dose, a combination of the lipidated IL-22 and anti-TNF, and, as positive control, anti-murine TNF at an optimal dose. Colitis severity was monitored during the study and at study end endoscopic scoring was performed. Colon length and weight were measured, and histological analysis on formalin-fixed paraffin sections performed by a blinded pathologist. Results At termination, all treatment groups showed reduced body weight loss and improved DAI scores compared to vehicle treated animals, which was significant for all but the suboptimal anti-TNF group. Combination treatment resulted in an additive treatment effect compared to single treatment alone, with mean DAI improving by 13% and 48% for the anti-TNF and IL-22 groups alone versus 68% in combination. Similar effects were observed for the endoscopic and histological scores. The compositive endoscopic score improved by 21% (anti-TNF) and 55% (IL-22) versus 66% for the combination, and histological scores 22% and 52% versus 66%. These combination results likely represent the maximum response that can be achieved in the model, since the improvements obtained are the same as those for the treatment positive control for the model (68% and 62% improvements in endoscopic and histological scores, respectively). Conclusion A novel long-acting lipidated IL-22, which acts on epithelial repair mechanisms, demonstrated strong and significant improvements on all measured parameters in a chronic DSS model of colitis. Combining the IL-22 mode-of-action with an immunomodulatory agent, exemplified by a murine anti-TNF antibody, demonstrated the complementarity of IL-22 agonism to existing treatment options. Clinical trials to assess safety and tolerability of lipidated IL-22 are expected to commence at the start of 2023.

Systematic Evaluation of AML-Associated Antigens Identifies Novel Anti-U5 snRNP200 Therapeutic Antibodies for the Treatment of AML

Numerous antibody-based immunotherapies are in development for AML including antibodies targeting CD47, CD70, CD123, CD33, and TIM3. However, systematic evaluation of the distribution of AML-associated antigens in combination with Fc receptors and the immune microenvironment required for antibody-mediated therapeutic responses have been limited. Additionally, efforts to maximize antibody Fc receptor engagement on immune effector cells in AML patients via Fc region engineering have not been explored. Here we applied a custom 36-color flow cytometry panel tailored for AML patient bone marrow along with proteogenomic assessment via CITE-seq to simultaneously assess known and novel antibody target expression on AML cells, immune microenvironment, and Fc receptor expression across immune subsets. Application to samples from 7 age-matched healthy donors and 51 newly diagnosed AML patients allowed for unbiased identification of the malignant blast population via UMAP projection. Quantification of differential antigen expression on blasts and leukemic stem cells versus normal hematopoietic stem and progenitor cell (HSPC) subsets, identified that out of 9 AML putative antibody targets (CD123, TIM3, CD33, CD47, CD90, CD38, CD25, CD70, U5 snRNP200), only U5 snRNP200 is expressed on blasts but not normal HSPCs (Fig. A). Characterization of the distribution of Fc receptors revealed that AML patients exhibit reduced cell-surface activating Fc receptors (CD16, CD32A) on NK and non-classical monocytes with concomitant increases in inhibitory (CD32B) Fc receptors on monocytes and B-cells. Moreover, AML patients had fewer classical monocytes and type 2 conventional dendritic (cDC2) cells than normal age-match control marrow. Given the unique cell surface expression of U5 snRNP200 on AML blasts compared with normal HSPCs, we deeply interrogated the distribution of this marker throughout normal and malignant hematopoiesis. While U5 snRNP200 expression was not seen on normal HSPCs, U5 snRNP200 was present on mature B-cells and a subset of NK cells in normal adult human and mouse hematopoietic cells. U5 snRNP200 is an RNA helicase which is an essential conserved component of the spliceosome. Its known function is limited to the nucleus and it is therefore unexpected that it would be expressed on the cell surface. To rigorously confirm expression of U5 snRNP200 on the cell membrane, we knocked in a HaloTag at the N-terminus of the locus encoding U5 snRNP200 within K562 cells and traced expression of tagged endogenous U5 snRNP200 protein across cellular compartments. This clearly revealed cell surface localization of the full-length protein on the surface of AML cells. We next conducted genome-wide CRISPR screens in two human AML cell lines to identify regulators of surface U5 snRNP200 expression. In both cell lines, the top gene required for cell surface U5 snRNP200 expression was CD32A. CRISPR knockout of CD32A in U937 cells reduced U5 snRNP200 surface expression, while restoration of CD32A rescued U5 snRNP200 surface expression. AML-associated expression of U5 snRNP200 was present on a number of syngeneic immunocompetent mouse models of AML including MLL-AF9, RN2 (MLL-AF9 + NRAS G12D), transgenic EVI1 rearranged/SF3B1K700E mutant, and Tet2/Zrsr2 double knockout mice. To test the therapeutic potential of targeting cell surface U5 snRNP200, we engineered several anti-murine U5 snRNP200 antibody variants featuring modified Fc regions to assess the possible roles of engagement of Fc receptors on immune cell subsets to enhance AML cell killing. In both the RN2 and EVI1/SF3B1 mutant models, anti-U5 snRNP200 antibodies featuring the Fc region modified to engage activating Fc receptors and induce antibody-dependent cellular cytotoxicity (IgG2a) provided superior survival benefit compared to IgG1 or IgG2b U5 snRNP200 antibodies or a mutant IgG1 antibody (IgG1 D265A) which does not bind Fc receptors (Fig. B). These data provide a high-density roadmap of the distribution of known and novel AML-associated antigens together with the Fc receptor distribution and immune microenvironment in AML. The results motivated discovery of a novel antibody-therapeutic targeting aberrant cell-surface U5 snRNP200 and research into mechanisms for cell surface trafficking of U5 snRNP200. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

TNFR2 antagonistic antibody induces the death of tumor infiltrating CD4+Foxp3+ regulatory T cells.

TNFR2 expression is a characteristic of highly potent immunosuppressive tumor infiltrating CD4+Foxp3+ regulatory T cells (Tregs). There is compelling evidence that TNF through TNFR2 preferentially stimulates the activation and expansion of Tregs. We and others, therefore, proposed that targeting TNFR2 may provide a novel strategy in cancer immunotherapy. Several studies have shown the effect of TNFR2 antagonistic antibodies in different tumor models. However, the exact action of the TNFR2 antibody on Tregs remained understood. TY101, an anti-murine TNFR2 antibody, was used to examine the effect of TNFR2 blockade on Treg proliferation and viability in vitro. The role of TNFR2 on Treg viability was further validated by TNFR2 knockout mice and in the TY101 antagonistic antibody-treated mouse tumor model. In this study, we found that an anti-mouse TNFR2 antibody TY101 could inhibit TNF-induced proliferative expansion of Tregs, indicative of an antagonistic property. To examine the effect of TY101 antagonistic antibody on Treg viability, we treated unfractionated lymph node(L.N.) cells with Dexamethasone (Dex) which was known to induce T cell death. The result showed that TY101 antagonistic antibody treatment further promoted Treg death in the presence of Dex. This led us to find that TNFR2 expression was crucial for the survival of Tregs. In the mouse EG7 lymphoma model, treatment with TY101 antagonistic antibody potently inhibited tumor growth, resulting in complete regression of the tumor in 60% of mice. The treatment with TY101 antagonistic antibody elicited potent antitumor immune responses in this model, accompanied by enhanced death of Tregs. This study, therefore, provides clear experimental evidence that TNFR2 antagonistic antibody, TY101, can promote the death of Tregs, and this effect may be attributable to the antitumor effect of TNFR2 antagonistic antibody.

Antibody Therapy: Past, Present and Future

The emergence of pandemics like SARS-CoV-2 and a gradual increase in Multidrug Resistant (MDR) infections highlights the need of innovation in therapeutics. Antibodies are one of the potential solutions for long. Antibody therapy has come very long way from the fight against infectious diseases, bacterial toxins to hybridoma technology and monoclonal antibodies. Hybridoma cells receive a deserving attention due to their antigen-specificity. But, as they were murine in origin, Human Anti Murine Antibody (HAMA) emerged. To achieve this, phage display was introduced. The emergence of molecular cloning lead to the generation of genetically engineered recombinant antibodies such as Fab, Fc, Variable Fragment (Fv), Single Chain Variable Fragments (scFv), single domain antibodies, diabodies; like scFv fragments to different moieties, such as drugs toxins, radionuclides, liposomes or quantum dots etc. Minimized antibodies have several advantages like rapid blood clearance, reduced immunogenicity, low retention time in non-target tissues, access to cryptic epitopes facilitating tumor penetration, rapid growth facilitating higher yield and lower production cost. This paper gives an overview of the history of development of antibodies and its fragments as potential therapeutic agents for the treatment of infectious diseases, one of the biggest challenges of humanity.

Abstract 1029: Dissecting the mechanism of action targeting TNFR2 with a lignd blocking anti-TNFR2 antibody that elicits potent anti-tumor activity

Abstract Tumor necrosis factor receptor-2 (TNFR2) is a TNF receptor superfamily member and has been reported to have restricted expression in the immune system, including potent suppressive Tregs, myeloid suppressor cells and endothelial cells. The therapeutic potential of targeting TNFR2 for cancers has been previously demonstrated but with conflicting data reported by different groups. In order to gain further insight into the mechanism of action (MoA) of targeting TNFR2, we used an anti-murine TNFR2 surrogate antibody (suAb) and tested its functional activities both in vitro and in vivo. suAb was able to bind murine TNFR2 with high sub-nanomolar affinity, in the meantime, it can also block the interaction between murine TNFα and TNFR2 at both protein and cellular levels. CD4+ T cells were isolated from spleens of wildtype Balb/c mice, the co-incubation of which with murine TNFα and IL-2 rendering the significant proliferation of Treg within the CD4+ T cell population. Addition of suAb can potently reduce Treg proliferation while downregulating the expression of TNFR2 on these Tregs. Further detailed analysis by using isolated mouse FoxP3+ Treg confirmed that suAb could effectively suppress murine Treg proliferation induced by TNFα and IL-2. In vivo, suAb treatment resulted in significant tumor growth inhibition across various syngeneic tumor models (CT26, EMT6 and LL/2) as single agent or when combined with anti-mPD-1 (CT26). Tumor infiltrating lymphocytes (TILs) analysis revealed dramatic increase of the effective-memory pool of both CD4+ and CD8+ T cells together with an significantly improved CD8/Treg ratio. In addition, treatment with suAb led to decreased expression of PD-1 on tumor infiltrating CD8+ T cells suggesting a potential relieved exhaustion phenotype after the treatment. Based on this careful MoA characterization, corresponding human anti-TNFR2 lead antibodies have been identified and are currently under development as potential novel treatment for cancer patients. Citation Format: Xiaofeng Zhao, Xiaoqing Liu, Zhenna Gao, Mengyu Wang, Wenjing Li, Ran Pang, Wenqing Yang, Zhuoxiao Cao, Renhong Tang. Dissecting the mechanism of action targeting TNFR2 with a lignd blocking anti-TNFR2 antibody that elicits potent anti-tumor activity [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 1029.

Abstract 1802: CD39 inhibition shapes the transcriptional landscape of myeloid cells and induces proinflammatory states in the CT26 syngeneic tumor model

Abstract Extracellular adenosine triphosphate (ATP) generated by tissue damage or immunogenic cell death initiates proinflammatory responses that are potently restricted by adenosine produced through ATP hydrolysis. The ectonucleotidases CD39 and CD73 limit immune responses by sequentially converting ATP to adenosine monophosphate (AMP) and adenosine, respectively. Increased activity of CD39, the rate-limiting enzyme in ATP hydrolysis in tumor microenvironments (TME), results in significant reductions in extracellular ATP. The subsequent accumulation of adenosine contributes to tumor immune escape, induction of angiogenesis, and metastatic progression. Although pharmacological targeting of CD39 has antitumor effects in preclinical models, the immunological mechanisms of therapeutic CD39 blockade have not been finely parsed. In this study, the immunological effects of CD39 inhibition on tumor infiltrating lymphocytes (TILs) were examined by single-cell transcriptome analysis. Mice bearing syngeneic CT26 tumors were treated with an anti-murine CD39 antibody that blocks the conversion of ATP to AMP. After 3 doses, tumors were harvested on Day 15 post-implant, dissociated, and enriched for CD45+ cells. Isolated TILs were captured in droplets, and single-cell sequencing libraries were generated through standard 10× Genomics protocols. Raw reads were pre-processed through the CellRanger pipeline. Data quality, normalization, integration, and clustering were performed with Seurat. Cell type annotation and differential expression was performed with SingleR and EdgeR, respectively. Several defined immunocyte populations identified in the CT26 TME were conserved across all conditions tested. These cell clusters segregated along the lymphoid/myeloid axis, with many sub-clusters identified for each major lineage. Data for each cell were aggregated in a pseudo-bulk RNA-seq analysis to define broad effects of CD39 blockade, which revealed major changes to immunocyte transcriptional landscapes. Notably, CD39 blockade upregulated several proinflammatory genes, including Gzmf, Gzmg, Cxcl9, and Csf3. Mapping of these changes to single-cell clusters revealed that CD39 blockade predominantly altered the transcriptional profiles of myeloid cell subsets, generally inducing proinflammatory gene modules. This analysis also demonstrated a significant effect of CD39 inhibition on plasmacytoid dendritic cells, inducing Cxcl2, Il1b, Gadd45g, and Fabp4 expression. Interestingly, CD39 blockade repressed Klk1, a kallikrein previously implicated in tumorigenesis. In summary, single-cell RNA-seq of the CT26 syngeneic tumor model suggests that CD39 inhibition predominantly shaped the transcriptional landscape of myeloid cells and generally induced proinflammatory conditions. Citation Format: Devapregasan Moodley, Mayra Carneiro, Sonia D. Gas, Austin Dulak, Ricard Masia, Secil Koseoglu, Matthew Rausch, Marisella Panduro, Michael C. Warren, John Stagg, Benjamin Lee, Pamela M. Holland, Vito J. Palombella, Andrew C. Lake. CD39 inhibition shapes the transcriptional landscape of myeloid cells and induces proinflammatory states in the CT26 syngeneic tumor model [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 1802.

Anti-RANKL monoclonal antibody and bortezomib prevent mechanical unloading-induced bone loss.

Bone loss is a major health concern for astronauts during long-term spaceflight and for patients during prolonged bed rest or paralysis. It is essential to develop therapeutic strategies to combat the bone loss occurring in people afflicted with disuse atrophy on earth as well as in astronauts in space, especially during prolonged missions. Although several drugs have been demonstrated for treating postmenopausal osteoporosis or bone-related diseases, their effects on microgravity-induced bone loss are still unclear. Here, we employed the hindlimb-unloading (HLU) tail suspension model and compared the preventive efficiencies of five agents including alendronate (ALN), raloxifene (Rox), teriparatide (TPTD), anti-murine RANKL monoclonal antibody (anti-RANKL) and proteasome inhibitor bortezomib (Bzb) on mechanical unloading-induced bone loss. Bone mineral density (BMD) was measured by quantitative computed tomography. The osteoblastic and osteoclastic activity were measured by serum ELISA, histology analysis, and histomorphometric analysis. Compared to the control, ALN and anti-RANKL antibody could restore bone mass close to sham levels by inhibiting bone resorption. Bzb could increase the whole bone mass and strength by inhibiting bone resorption and promoting bone formation simultaneously. Meanwhile, Rox did not affect bone loss caused by HLU. TPTD stimulated cortical bone formation but the total bone mass was not increased significantly. We demonstrated for the first time that anti-RANKL antibody and Bzb had a positive effect on preventing mechanical unloading-induced bone loss. This finding puts forward the potential use of anti-RANKL and Bzb on bone loss therapies or prophylaxis of astronauts in spaceflight.

Impact of Humoral Immunogenicity (Anti-mCAR19 Antibodies) on CTL019 Cellular Kinetics, Efficacy, and Safety

Background: The humoral immunogenicity of CAR19, a chimeric antigen receptor with a murine scFV domain developed for treatment with CTL019 (tisagenlecleucel) in relapsed/refractory (R/R) pediatric and young adult acute lymphoblastic leukemia (ALL), was evaluated in 2 studies (ELIANA [NCT02435849]; ENSIGN [NCT02228096]). To date, little is known about the presence and impact of preexisting or treatment-induced anti-murine (m)CAR19 antibodies in patients treated with CAR T-cell therapy.Methods: Anti-mCAR19 antibodies were measured in patients from ELIANA and ENSIGN trials before and after CTL019 infusion to evaluate the impact of anti-mCAR19 antibodies on cellular kinetics, efficacy, and safety. Data were pooled from ELIANA (n = 68) and ENSIGN (n = 29). Anti-mCAR19 antibodies were captured by mCAR19-transfected Jurkat cells and wild-type Jurkat cells. Following incubation and washing, an R-phycoerythrin (PE)-labeled anti-IgG/M F(ab')2 fragment was added for detection of anti-mCAR19 antibodies using flow cytometry and reported as median fluorescence intensity (MFI). Exploratory assay development included assessment of whether the presence of immunoglobulins after IVIG therapy in clinical samples would interfere with the anti-mCAR19 antibody assay. Impact of preexisting immunogenicity, as detected by MFI levels, was evaluated using cellular kinetic, efficacy, and safety endpoints. The impact of treatment-induced immunogenicity (defined as having an increase in anti-mCAR19 antibody levels over baseline) was assessed by calculating the fold change between preexisting (ie, baseline) levels and postinfusion levels.Results: Approximately 90% of patients displayed preexisting anti-mCAR19 antibodies; a similar incidence was detected in healthy volunteer samples, as observed during assay development. Approximately 35% of patients developed treatment-induced anti-mCAR19 antibodies. No apparent relationship between CTL019 expansion (AUC0-28d) and preexisting or treatment-induced anti-mCAR19 antibodies was identified (r2 < 0.001 and r2 = 0.006, respectively); similar results were seen for Cmax (Figure 1a). Presence of anti-mCAR19 after infusion did not appear to influence the persistence of transgene or day 28 response (Figure 1b). Kaplan-Meier curves showed that the presence of preexisting and treatment-induced anti-mCAR19 antibodies did not appear to impact the duration of response or event-free survival (Figure 1c). Strip plots showed consistent levels of preexisting and treatment-induced anti-mCAR19 antibodies across patients with safety events (grade 0/1/2/3/4), including CRS, neutropenia, thrombocytopenia, and neurological events. There was no apparent relationship between treatment- induced anti-mCAR19 antibodies with B-cell recovery categories (recovery ≤ 3 months, > 3 months and ≤ 6 months, > 6 months, and ongoing sustained B-cell aplasia). There was also no association in patients at the time of B-cell recovery with the presence of treatment-induced anti-mCAR19 antibodies following CTL019 infusion. B-cell aplasia requiring immunoglobulin replacement therapy (IVIG) occurred following CTL019 in the majority of patients. The CTL019 concentration time profiles for patients with treatment-induced anti-mCAR19 antibodies were categorized by the time following IVIG administration (within 1 week, 2 weeks, or > 3 weeks of IVIG administration). The results revealed no impact of the time at which IVIG was administered on the in vivo expansion and persistence of the transgene.Conclusions: We report the first comprehensive assessment of the impact of anti-mCAR antibodies on clinically relevant endpoints for CAR therapy. Determination of immunogenicity is an important endpoint required by health authorities for biologic drugs, and these analyses demonstrate the importance of characterizing the impact on clinical endpoints for CAR therapies. These analyses in patients with pediatric R/R ALL revealed a surprisingly high frequency of baseline anti-mCAR19 antibodies and showed that the presence of preexisting and treatment-induced anti-mCAR19 antibodies did not impact the cellular kinetics, safety, and efficacy of CTL019. Cell-mediated immunity studies are ongoing. [Display omitted] DisclosuresMueller:Novartis Pharmaceuticals Corporation: Employment. Waldron:Novartis Pharmaceuticals Corporation: Employment. Sickert:Novartis Institutes for BioMedical Research: Employment. Grupp:University of Pennsylvania: Patents & Royalties; Novartis Pharmaceuticals Corporation: Consultancy, Other: grant; Adaptimmune: Consultancy; Jazz Pharmaceuticals: Consultancy. Maude:Novartis Pharmaceuticals: Consultancy, Other: Medical Advisory Boards. Levine:Novartis Pharmaceuticals Corporation: Membership on an entity's Board of Directors or advisory committees. Laetsch:Novartis Pharmaceuticals Corporation: Consultancy. Pulsipher:Novartis Pharmaceuticals Corporation: Consultancy, Other: Phase II steering committee; Chimerix: Other: Advisory board Dec 2015; Jazz Pharmaceuticals: Other: advisory board, education; CSL Behring: Other: advisory board Feb 2017; Adaptive: Other: Advisory board 6/17. Boyer:Novartis Pharmaceuticals Corporation: Honoraria. August:Novartis Pharmaceuticals Corporation: Consultancy. Awasthi:Novartis Pharmaceuticals Corporation: Employment. Levine:GE Healthcare: Consultancy; Novartis Pharmaceuticals Corporation: Patents & Royalties, Research Funding; Brammer Bio: Consultancy; Tmunity Therapeutics: Equity Ownership, Research Funding. June:WIRB/Copernicus Group: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celldex: Honoraria, Membership on an entity's Board of Directors or advisory committees; Immune Design: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Novartis: Patents & Royalties, Research Funding; Tmunity Therapeutics: Equity Ownership, Research Funding. Taran:Novartis Pharmaceuticals Corporation: Employment, Equity Ownership. Wood:Novartis Pharmaceuticals Corporation: Employment, Equity Ownership. Myers:Novartis Pharmaceuticals Corporation: Consultancy.

Interleukin-17-Producing CD4+ T Cells Promote Inflammatory Response and Foster Disease Progression in Hyperlipidemic Patients and Atherosclerotic Mice.

Atherosclerosis is a chronic inflammatory disease. Interleukin-17-producing CD4+ T cells (Th17 cells) play important roles in the progression of atherosclerosis. However, most of the studies were focused on the advanced stage of atherosclerosis. In the current study, we investigated the roles of Th17 cells, relevant mechanisms in hyperlipidemic patients, and different stages of atherosclerotic mice. Human blood samples were collected, and percentages of Th17 cells, macrophages, and neutrophils were analyzed by flow cytometry. ApoE−/− mice were fed with high-fat diet (HFD) and sacrificed at different time points to evaluate the infiltration of inflammatory cells at different stages of atherosclerosis. Furthermore, essential mechanisms of IL-17A in atherosclerotic inflammatory milieu formation were studied in vivo by intraperitoneal injection with monoclonal anti-murine IL-17 antibody. Our study reveals the higher percentages of Th17 cells, monocytes, and neutrophils in hyperlipidemic patients compared to healthy donors. Meanwhile, we also identify an infiltration of Th17 cells in the early stage of atherosclerosis (4 weeks after HFD), which maintains at high level until late stage of atherosclerosis (20 weeks after HFD). What is more, inflammatory cells including macrophages and neutrophils were also accumulated in atherosclerotic lesions. Neutralization of IL-17 in ApoE−/− mice resulted in less infiltration of macrophages and neutrophils and smaller atherosclerotic lesions. Importantly, in accordance with what is found in the mouse model, positive correlations between Th17 cells and macrophages or neutrophils were observed in hyperlipidemic patients. In conclusion, our clinical and mouse model data together reveal a pro-atherogenic role of Th17 cells through the promotion of inflammation in hyperlipidemic conditions and different stages of atherosclerosis, which further supports the notion that IL-17 may be a therapy target for the treatment of atherosclerosis.

Phase II study of zolbetuximab plus pembrolizumab in claudin 18.2: Positive locally advanced or metastatic gastric or gastroesophageal junction adenocarcinoma (G/GEJ)—ILUSTRO Cohort 3.

TPS260 Background: Five-year survival with advanced G/GEJ is poor, and limited biomarkers exist to inform optimal treatment selection. Pembrolizumab, an anti–programmed death-1 receptor (PD-1) antibody, is approved for advanced/metastatic PD-ligand 1–positive (PD-L1+) G/GEJ that progressed after ≥2 lines of therapy. The transmembrane tight junction protein claudin 18.2 (CLDN18.2) is normally confined to gastric mucosa but is often overexpressed in G/GEJ with roughly one-third of patients (pts) having high expression (≥75%). Zolbetuximab, a chimeric IgG1 monoclonal antibody, binds to CLDN18.2 and mediates cancer cell death through antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity. Phase 2 (NCT01630083) results showed prolonged survival with zolbetuximab + epirubicin, oxaliplatin, and capecitabine (EOX) vs EOX alone in G/GEJ. Results of nonclinical studies showed enhanced antitumor activity with zolbetuximab + anti-murine PD-1 antibody, and it was hypothesized that a combination with pembrolizumab (new Cohort 3) might augment ADCC and antitumor immune response in CLDN18.2 overexpressing G/GEJ. Methods: This phase 2 open-label study (NCT03505320) will enroll ~112 adult pts from 22 sites in 5 countries into 3 cohorts; this abstract describes Cohort 3 (~62 pts). Key eligibility criteria are advanced/metastatic G/GEJ, measurable disease (RECIST v1.1), adequate organ function and performance status, and high/intermediate (Cohort 3A) or high (Cohort 3B) expression of CLDN18.2. Central testing of tumor tissue will determine CLDN18.2 expression; pts are considered CLDN18.2 positive (CLDN18.2+) if ≥75% (high) or ≥50% to &lt; 75% (intermediate) of tumor cells demonstrate moderate-to-strong membranous IHC staining. Patients in Cohort 3B are required to be PD-L1+, defined as a combined positive score ≥1 (IHC staining per the Dako 22C3 PD-L1 assay). Patients will receive zolbetuximab + pembrolizumab in the third/later line in Cohort 3A and third line in Cohort 3B. In Cohort 3A (safety cohort), zolbetuximab will be administered at a loading dose of 800 mg/m2 IV on Day 1 Cycle 1 followed by 600 mg/m2 IV every 3 weeks; a reduction from 600 mg/m2 every 3 weeks is permitted. Pembrolizumab 200 mg IV will be administered on Day 1 of each 21-day cycle. Cohort 3B (expansion cohort) zolbetuximab dose is determined from results of Cohort 3A. Imaging will occur every 6 weeks for 24 weeks and every 12 weeks thereafter. The primary endpoint is objective response rate; additional endpoints include duration of response, disease control rate, and progression-free survival by independent review committee and investigator assessment. Pharmacokinetics, safety/tolerability, quality of life, and immunogenicity will be assessed. The study is currently recruiting pts. Clinical trial information: NCT03505320.

Therapy of Myeloid Leukemia using Novel Bispecific Fusion Proteins Targeting CD45 and 90Y-DOTA

Pretargeted radioimmunotherapy (PRIT) has been investigated as a multi-step approach to decrease relapse and toxicity for high-risk acute myeloid leukemia (AML). Relevant factors including endogenous biotin and immunogenicity, however, have limited the use of PRIT with an anti-CD45 antibody streptavidin conjugate and radiolabeled DOTA-biotin. To overcome these limitations we designed anti-murine and anti-human CD45 bispecific antibody constructs using 30F11 and BC8 antibodies, respectively, combined with an anti-yttrium (Y)-DOTA single-chain variable fragment (C825) to capture a radiolabeled ligand. The bispecific construct targeting human CD45 (BC8-Fc-C825) had high uptake in leukemia HEL xenografts [7.8 ± 0.02% percent injected dose/gram of tissue (% ID/g)]. Therapy studies showed that 70% of mice with HEL human xenografts treated with BC8-Fc-C825 followed by 44.4 MBq (1,200 μCi) of 90Y-DOTA-biotin survived at least 170 days after therapy, while all nontreated controls required euthanasia because of tumor progression by day 32. High uptake at sites of leukemia (spleen and bone marrow) was also seen with 30F11-IgG1-C825 in a syngeneic disseminated SJL murine leukemia model (spleen, 9.0 ± 1.5% ID/g and bone marrow, 8.1 ± 1.2% ID/g), with minimal uptake in all other normal organs (<0.5% ID/g) at 24 hours after 90Y-DOTA injections. SJL leukemia mice treated with the bispecific 30F11-IgG1-C825 and 29.6 MBq (800 μCi) of 90Y-DOTA-biotin had a survival advantage compared with untreated leukemic mice (median, 43 vs. 30 days, respectively; P < 0.0001). These data suggest bispecific antibody-mediated PRIT may be highly effective for leukemia therapy and translation to human studies.

Blocking Interleukin-33 Alleviates the Joint Inflammation and Inhibits the Development of Collagen-Induced Arthritis in Mice.

Rheumatoid arthritis (RA) is considered a systemic chronic inflammatory joint disease characterized by chronic synovitis and cartilage and bone destruction. Interleukin-33 (IL-33) is a proinflammatory cytokine which is highly expressed in the synovium of RA patients and the joints of mice with collagen-induced arthritis (CIA) and exacerbates CIA in mice. However, the role of the IL-33-neutralizing antibody in the murine model of CIA remains unclear. In the present study, CIA mice were given intraperitoneally with polyclonal rabbit anti-murine IL-33 antibody (anti-IL-33) or normal rabbit IgG control after the first signs of arthritis. Administration of anti-IL-33 after the onset of disease significantly reduced the severity of CIA and joint damage compared with controls treated with normal rabbit IgG. Anti-IL-33 treatment also significantly decreased the serum levels of interferon-γ(IFN-γ),IL-6, IL-12, IL-33, and tumor necrosis factor-α (TNF-α). Moreover, anti-IL-33 treatment significantly downregulated the production of IFN-γ, IL-6, IL-12, IL-33, and TNF-α in ex vivo-stimulated spleen cells. Together, our results indicate that the IL-33-neutralizing antibody may provide a therapeutic strategy for RA by inhibiting the release of proinflammatory cytokines.

Chronic glucose-dependent insulinotropic polypeptide receptor (GIPR) agonism desensitizes adipocyte GIPR activity mimicking functional GIPR antagonism

Antagonism or agonism of the glucose-dependent insulinotropic polypeptide (GIP) receptor (GIPR) prevents weight gain and leads to dramatic weight loss in combination with glucagon-like peptide-1 receptor agonists in preclinical models. Based on the genetic evidence supporting GIPR antagonism, we previously developed a mouse anti-murine GIPR antibody (muGIPR-Ab) that protected diet-induced obese (DIO) mice against body weight gain and improved multiple metabolic parameters. This work reconciles the similar preclinical body weight effects of GIPR antagonists and agonists in vivo, and here we show that chronic GIPR agonism desensitizes GIPR activity in primary adipocytes, both differentiated in vitro and adipose tissue in vivo, and functions like a GIPR antagonist. Additionally, GIPR activity in adipocytes is partially responsible for muGIPR-Ab to prevent weight gain in DIO mice, demonstrating a role of adipocyte GIPR in the regulation of adiposity in vivo.