Antagonistic Antibody Research Articles

Phase 1/2 Clinical Study of VRDN-001, A Full Antagonist Antibody to the Insulin-Like Growth Factor-1 Receptor (IGF-1R), in Patients with Thyroid Eye Disease (TED) (P3-9.001)

Phase 1/2 Clinical Study of VRDN-001, A Full Antagonist Antibody to the Insulin-Like Growth Factor-1 Receptor (IGF-1R), in Patients with Thyroid Eye Disease (TED) (P3-9.001)

Abstract CT040: A first-in-human phase 1 trial of IO-108, an antagonist antibody targeting LILRB2 (ILT4), as monotherapy and in combination with pembrolizumab in adult patients with advanced relapsed or refractory solid tumors: Dose escalation study

Abstract Background: IO-108 is a fully human IgG4 monoclonal antibody with high affinity and specificity towards LILRB2 (also known as ILT4). It blocks the interaction of LILRB2 with the known ligands for LILRB2, including HLA-G, ANGPTLs, SEMA4A and CD1d. Methods: IO-108-CL-001 is a first-in-human, Phase 1a/1b study in patients with relapsed/refractory solid tumors (NCT05054348). The dose escalation phase enrolled patients into escalating dose cohorts of IO-108 (60-1800 mg, Q3W IV) as monotherapy or in combination with pembrolizumab. Patients with disease progression on monotherapy could crossover to the combination arm. Primary objectives were safety and tolerability, and identification of the recommended phase 2 dose (RP2D). Secondary and exploratory objectives include evaluation of pharmacokinetics (PK), immunogenicity, pharmacodynamic (PD) biomarker effects and anti-tumor activity as measured by objective response rate (RECIST 1.1). Results: Twenty-five relapsed/refractory solid tumor patients (median 4.5 prior lines of therapy for monotherapy and 3.6 for combination therapy) were treated with IO-108 monotherapy (n=12) or IO-108 + pembrolizumab (n=13). IO-108 was well-tolerated up to the maximal administered dose of 1800 mg Q3W as monotherapy and in combination with pembrolizumab, with no SAEs related to IO-108 and no DLTs observed. Maximum tolerated dose (MTD) was not reached. Full receptor occupancy through 21 days was achieved at ≥600 mg. The preliminary RP2D is 1200 mg Q3W. Dose-expansion cohorts of IO-108 monotherapy and IO-108 + anti-PD-1 are ongoing.Twenty-three patients were efficacy evaluable (11 monotherapy, 12 combination therapy plus 1 crossover). Overall response rate was 9% in monotherapy cohort (1 Merkel cell carcinoma, prior pembrolizumab followed by nivolumab/ipilimumab) and 23% in combination therapy (2 cholangiocarcinoma, 1 MSS CRC with neuroendocrine features)​. The best overall response was 1 CR, 4 SD among monotherapy, and was 3 PR, 4 SD among combination therapy.​ The 4 responding patients remain on study with an on-going treatment duration of 8 to 12 months as of abstract submission.Consistent with the MOA, clinical benefit correlated with baseline characteristics and post-treatment changes in PD biomarkers including reprogramming of myeloid cells and activation of T cells. Conclusion: The initial encouraging data support further development of IO-108, both as monotherapy and in combination with anti-PD-(L)1 for patients with advanced solid tumors. Citation Format: Matthew H. Taylor, Manish R. Patel, John D. Powderly, Paul Woodard, Luke Chung, Hongyu Tian, Xiang Hong, Kyu Hong, Donna Valencia, Tao Huang, Xiao Min Schebye, Charlene Liao, Aung Naing. A first-in-human phase 1 trial of IO-108, an antagonist antibody targeting LILRB2 (ILT4), as monotherapy and in combination with pembrolizumab in adult patients with advanced relapsed or refractory solid tumors: Dose escalation study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT040.

TIGIT mediates activation-induced cell death of ILC2s during chronic airway allergy.

While group-2 innate lymphoid cells (ILC2s) are highly proliferative in allergic inflammation, the removal of overactivated ILC2s in allergic diseases has not been investigated. We previously showed that chronic airway allergy induces "exhausted-like" dysfunctional ILC2s expressing T cell immunoreceptor with Ig and ITIM domains (TIGIT). However, the physiological relevance of these cells in chronic allergy remains elusive. To precisely identify and monitor TIGIT+ ILC2s, we generated TIGIT lineage tracer mice. Chronic allergy stably induced TIGIT+ ILC2s, which were highly activated, apoptotic, and were quickly removed from sites of chronic allergy. Transcripts from coding genes were globally suppressed in the cells, possibly due to reduced chromatin accessibility. Cell death in TIGIT+ ILC2s was enhanced by interactions with CD155 expressed on macrophages, whereas genetic ablation of Tigit or blockade by anti-TIGIT antagonistic antibodies promoted ILC2 survival, thereby deteriorating chronic allergic inflammation. Our work demonstrates that TIGIT shifts the fate of ILC2s toward activation-induced cell death, which could present a new therapeutic target for chronic allergies.

GDNF family receptor alpha-like antagonist antibody alleviates chemotherapy-induced cachexia in melanoma-bearing mice.

Patients with cancer undergoing chemotherapy experience cachexia with anorexia, body weight loss, and the depletion of skeletal muscles and adipose tissues. Effective treatment strategies for chemotherapy-induced cachexia are scarce. The growth differentiation factor 15 (GDF15)/GDNF family receptor alpha-like (GFRAL)/rearranged during transfection (RET) axis is a critical signalling pathway in chemotherapy-induced cachexia. In this study, we developed a fully human GFRAL antagonist antibody and investigated whether it inhibits the GDF15/GFRAL/RET axis, thereby alleviating chemotherapy-induced cachexia in tumour-bearing mice. Anti-GFRAL antibodies were selected via biopanning, using a human combinatorial antibody phage library. The potent GFRAL antagonist antibody A11 was selected via a reporter cell assay and its inhibitory activity of GDF15-induced signalling was evaluated using western blotting. To investigate the in vivo function of A11, a tumour-bearing mouse model was established by inoculating 8-week-old male C57BL/6 mice with B16F10 cells (n=10-16 mice per group). A11 was administered subcutaneously (10mg/kg) 1day before intraperitoneal treatment with cisplatin (10mg/kg). Animals were assessed for changes in food intake, body weight, and tumour volume. Plasma and key metabolic tissues such as skeletal muscles and adipose tissues were collected for protein and mRNA expression analysis. A11 reduced serum response element-luciferase reporter activity up to 74% (P<0.005) in a dose-dependent manner and blocked RET phosphorylation up to 87% (P=0.0593), AKT phosphorylation up to 28% (P=0.0593) and extracellular signal regulatory kinase phosphorylation up to 75% (P=0.0636). A11 inhibited the action of cisplatin-induced GDF15 on the brainstem and decreased GFRAL-positive neuron population expressing c-Fos in the area postrema and nucleus of the solitary tract by 62% in vivo (P<0.05). In a melanoma mouse model treated with cisplatin, A11 recovered anorexia by 21% (P<0.05) and tumour-free body weight loss by 13% (P<0.05). A11 significantly improved the cisplatin-induced loss of skeletal muscles (quadriceps: 21%, gastrocnemius: 9%, soleus: 13%, P<0.05) and adipose tissues (epididymal white adipose tissue: 37%, inguinal white adipose tissue: 51%, P<0.05). Our study suggests that GFRAL antagonist antibody may alleviate chemotherapy-induced cachexia, providing a novel therapeutic approach for patients with cancer experiencing chemotherapy-induced cachexia.

Abstract 5184: Anti-HVEM mAb therapy improves antitumoral immunity both in vitro and in vivo, in a novel transgenic mouse model expressing human HVEM and BTLA molecules challenged with HVEM expressing tumors

Abstract TNFRF-14/HVEM is the ligand for BTLA and CD160 negative immune co-signaling molecules as well as viral proteins. Its expression is dysregulated with an overexpression in tumors and a connection with tumors of adverse prognosis. We developed C57BL/6 mouse models co-expressing human huBTLA and huHVEM as well as antagonistic monoclonal antibodies (mAbs) that completely prevent the interactions of HVEM with its ligands. Here, we show that the anti-HVEM18-10 mAb increases primary human αβ-T cells activity alone (CIS-activity) or in the presence of HVEM-expressing lung or colorectal cancer cells in vitro (TRANS-activity). Anti-HVEM18-10 synergizes with anti-PD-L1 mAb to activate T cells in the presence of PDL-1 positive tumors, but is sufficient to trigger T cell activation in the presence of PD-L1 negative cells. In order to better understand HVEM18-10 effect in vivo and especially disentangle its CIS and TRANS effects, we developed a knock-in (KI) mouse model expressing human BTLA (huBTLA+/+) and a KI mouse model expressing both human BTLA and human HVEM (huBTLA+/+/huHVEM+/+ (DKI)). In vivo pre-clinical experiments performed in both mouse models showed that HVEM18-10 treatment was efficient to decrease human HVEM+ tumor growth. In the DKI model, anti-HVEM 18-10 treatment induces a decrease of exhausted CD8+ T cells and regulatory T cells and an increase of Effector memory CD4+ T cells within the tumor. Interestingly, mice which completely rejected tumors (± 20%) did not develop tumors upon re-challenge in both settings, therefore showing a marked T cell-memory phenotype effect. Altogether, our preclinical models validate anti-HVEM18-10 as a promising therapeutic antibody to use in clinics as a monotherapy or in combination with existing immunotherapies (anti-PD1/anti-PDL-1/anti-CTLA-4). Citation Format: Laurent GORVEL, Clemence Demerle, Marielle Mello, Sonia Pastor, Clara Degos, Ana Zarubica, Fabien Angelis, Frederic Fiore, Jacques Nunes, Bernard Malissen, Laurent Greillier, Geoffrey Guittard, Herve Luche, Fabrice Barlesi, Daniel Olive. Anti-HVEM mAb therapy improves antitumoral immunity both in vitro and in vivo, in a novel transgenic mouse model expressing human HVEM and BTLA molecules challenged with HVEM expressing tumors. [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 5184.

Abstract 6384: ATG-034, an LILRB4 antagonist antibody, reinvigorates dendritic cells and prevents tumor progression

Abstract Background: Dendritic cells (DCs) are vital for initiating antigen-specific T cell-dependent antitumor immune responses. However, emerging evidence reveals that local DCs within the tumor microenvironment (TME) are tolerized to facilitate immune evasion. Reprogramming of DCs is recognized as a promising strategy for tumor immunotherapy. Leukocyte immunoglobulin-like receptor B4 (LILRB4) is an inhibitory receptor belonging to the LILR family which is mainly expressed on normal myeloid cells and myeloid-derived malignant cells. It is upregulated on tolerogenic DCs (tolDCs), which exhibit low expression levels of costimulatory molecules and resistance to DC maturation. Targeting LILRB4 to reprogram tolDCs has been reported to be a promising strategy for cancer treatment. Here we report the preclinical development of an LILRB4 antagonist antibody, ATG-034. Method: The protein-based and cell-based binding affinity of ATG-034 were measured using SPR, ELISA and FACS analysis. Fc receptor (FcR) stimulation assay was used to evaluate the ability of ATG-034 to block the interaction of LILRB4 with its ligand fibronectin. ATG-034-mediated enhancement of antigen presentation and co-stimulation ability of DCs was determined by FACS analysis for the change of surface expression of HLA-DR, HLA-ABC, CD86, and CD206. The mixed lymphocyte reaction (MLR) assay was used to assess the immunomodulatory potential of ATG-034. The in vivo antitumor efficacy of ATG-034 was evaluated in a radiation therapy-resistant murine Lewis lung carcinoma (LLC) syngeneic model. Results: ATG-034 binds to LILRB4 protein with a single-digit nM affinity. It potently reversed the fibronectin-mediated inhibition of FcR-driven TNF-α cytokine production. TolDCs were reprogrammed by ATG-034 to immunogenic DCs with significant upregulation of the expression of HLA-DR, HLA-ABC, CD86 and downregulation of the expression of CD206. Furthermore, ATG-034 remarkably reinvigorated tolDCs for priming T cell activation with noticeable upregulation of the expression of CD25 and the secretion of IFN-γ, enhancing antitumor immunity. In addition, 10 mg/kg ATG-034 significantly inhibited the LLC tumor growth in vivo with a TGI of 40.28%, while a benchmark antibody only demonstrated a 24.43% TGI. Conclusion: Our data show that ATG-034 reprograms tolDC, enhancing anti-tumor immunity, and demonstrates potent in vivo anti-tumor efficacy. Therefore, ATG-034 may be a promising strategy for the treatment of cancer. Citation Format: Ao Sun, Enlin Zheng, Huili Cao, Mengshi Cao, Suya Bai, Peng Chen, Linjie Tian, Jay Mei, Bo Shan, Bing Hou. ATG-034, an LILRB4 antagonist antibody, reinvigorates dendritic cells and prevents tumor progression [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 6384.

Abstract 6376: Discovery and preclinical characterization of dual antagonist antibodies targeting both LILRB1 and LILRB2 that enhance innate and adaptive anti-cancer immune responses

Abstract Background: One cause for the failure of checkpoint inhibitors is the immunosuppressive nature of the tumor microenvironment. LILRB1 (ILT2) and LILRB2 (ILT4) are ITIM-containing inhibitory receptors that recognize HLA Class 1 and nonclassical ligands (e.g., HLA-A, HLA-G, etc.). LILRB1 is expressed on myeloid cells and subsets of B, NK, and T cells, while LILRB2 expression is mostly restricted to myeloid cells. Interaction of LILRB1 and LILRB2 receptors with HLA ligands promotes an inhibitory milieu that prevents T cells from attacking cancer cells. The distinct pattern of expression and function of these lymphoid and myeloid checkpoints suggests complementary targeting approaches for cancer immunotherapy. Dual blockade of LILRB1 and LILRB2 receptors by a single antibody that restores both innate and adaptive immune responses is a promising strategy to enhance efficacy of checkpoint inhibitors. Methods: Dual LILRB1 and LILRB2 targeting antibodies were cloned from B cells derived from rabbits immunized with human LILRB2 recombinant protein, and subsequently humanized. Antibodies were evaluated for binding to human LILRB1 and LILRB2 proteins. Dual targeting antibodies were evaluated in a panel of functional and phenotypic assays. Selected antibodies were further tested for efficacy in a humanized NSG-SGM3 tumor model. Results: Dual antibodies were selected based on binding to recombinant human LILRB1 and LILRB2 protein, as well as blocking of HLA-G binding. These antibodies demonstrated binding to cells expressing LILRB1 and LILRB2, with no appreciable binding to other family members. Lead antibodies demonstrated activity in functional cell-based assays modeling LILRB1- or LILRB2-mediated immunosuppression. Dual antibodies also enhanced IFN-γ production by LPS-stimulated human PBMC. Selected clones restored T-cell function from M2c macrophage-mediated suppression in coculture with CD8+ T cell, and enhanced the tumoricidal activity of NK cells. Importantly, the lead antibody demonstrated in vivo efficacy with significant tumor growth inhibition and tumor regression in an SK-MEL-5 tumor model in humanized NSG-SGM3 mice. Conclusions: We have identified dual antagonist antibodies targeting both LILRB1 and LILRB2 antibodies that restore both innate and adaptive immune responses. Additionally, dual antibodies restored CD8+ T cell activation from macrophage-mediated suppression and enhanced NK cell cytotoxic activity. These data provide a strong rationale for further development of dual antibodies as an anti-cancer immunotherapy. Citation Format: Meghan Zuck, Myriam Bouchlaka, Huyen Dinh, Kevin Green, Francisco Zapata, Ramya Chandrasekaran, Tatyana Pisarenko, Lauren Loh, Gajendra S. Naika, Meilyn Sylvestre, Jacob Heit, Raymond Fox, Darbie Whitman, Tom Graddis, Kamal D. Puri, Peter Probst. Discovery and preclinical characterization of dual antagonist antibodies targeting both LILRB1 and LILRB2 that enhance innate and adaptive anti-cancer immune responses [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 6376.

Abstract 2283: An immunosuppressive ectoenzyme-expressing T cell population is associated with non-responsiveness to immune checkpoint blockade in metastatic melanoma patients

Abstract The development of antibodies to block immune checkpoints like PD-1, CTLA-4, PD-L1 or LAG-3 has been a major advance in cancer therapy. This has led to the approval of multiple antibodies for metastatic melanoma and other malignancies. A large proportion of the patients do not benefit from CTLA-4 or PD-1 antagonistic antibodies. Understanding the mechanisms of resistance to immunotherapy is thus critical to improve its effectiveness. Previously we identified and validated a novel population of cells characterized by phenotype CD3+CD4+CD127-GARP-CD38+CD39+ that was associated with non-responsiveness to immune checkpoint blockade (ICB) in metastatic melanoma patients (Woods et al, 2020). CD38 and CD39 are ectonucleotidases, that convert intracellular ATP or NADPH to extracellular adenosine which has suppressive effect on T cell functions. We used high-dimension flow cytometry and bulk RNA seq to characterize the phenotype of these cells and evaluated the functions by T cell suppression assays. All characterizations and functional experiments were performed on peripheral blood samples from metastatic melanoma patients undergoing anti-PD1 therapy. The characterization of this population by flow cytomtery shows an enhanced expression of activation markers (4-1BB, HLA-DR, OX-40, GITR), inhibitory receptors (Tim3, CTLA-4, PD-1) and ligands (PD-L1, CD244) and an exhausted phenotype (TOXhiTCF1low). Further functional studies performed on these cells showed a suppressive phenotype, as observed by a significant decrease in the proliferation of target autologous CD4 (p=0.001) and CD8 (p=0.0012) T cells when in co-culture with these cells, compared to the controls. The transcriptomic features of these cells showed an upregulation of genes associated with proliferation (e.g. CDC20, TK1, DHFR, MYL6B), as well as exhaustion (e.g. upregulated TOX), consistent with the flow cytometry data. We also evaluated the presence of these cells and their correlation with the outcome in other melanoma datasets. By performing gene set variation analysis (GSVA) on existing single-cell RNA seq datasets of tumor derived immune cells in melanoma, we have found that an intra-tumoral CD3+CD4+CD127-GARP-CD38+CD39+ signature is associated with resistance to immunotherapy (p= 0.000003). We identified a novel population of ectonucleotidase expressing T cells in peripheral blood and tumor to be associated with immunotherapy resistance in metastatic melanoma patients. This population showed an exhausted phenotype and suppressed autologous T-cells in vitro. Our data identifies CD3+CD4+CD127-GARP-CD38+CD39+ cells as a potential target to enhance the efficacy of immunotherapy in advanced melanoma patients. Citation Format: Ankita Mitra, Brian Thompson, David M. Woods, Jeffrey S. Weber. An immunosuppressive ectoenzyme-expressing T cell population is associated with non-responsiveness to immune checkpoint blockade in metastatic melanoma patients [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 2283.

Abstract 2340: Development of a CCR8 monoclonal antibody which blocks CCR8 signaling and abolishes the immunosuppressive function of Treg for the treatment of cancer

Abstract Within the tumor microenvironment (TME), regulatory T (Treg) cells are one attractive cell type for targeting as they play a critical role in immunosuppression. Therapeutic strategies that specifically inhibit tumor-infiltrating Tregs while sparing peripheral and normal tissue Tregs are highly desirable. The tumor-associated Tregs express the chemokine receptor CCR8, which plays a role in the induction, expansion, chemotactic migration, and immunosuppression of tumor-associated Tregs. Thus, targeted inhibition of CCR8 is a potential therapeutic strategy against cancer. We have developed a monoclonal antibody antagonist of CCR8, IPG0521, which potently inhibited the receptor-mediated signaling and chemotaxis in Treg cells with single digital nanomolar IC50. RNA sequencing (RNA-seq)analysis indicated that CCL1-induced up-regulation of immunosuppressive genes, including PD-1, CTLA4, IL-10, TIGIT etc., were reversed by IPG0521 in tumor-derived Treg cells. IPG0521 potently inhibited the growth of multiple tumor types in both syngeinic and immune-humanized mouse models, including lung cancer, liver cancer, breast cancer, via inhibiting Treg and activating CD8+ T cells. These data pave the way for the development of IPG0521, which is under IND filing, as a novel therapeutic agent against cancer. Citation Format: Guohuang Fan, Jianfei Wang, Na Wang, Yuanyuan Zhang, Yong Zhang, Binle Tian, Xuebing Jia. Development of a CCR8 monoclonal antibody which blocks CCR8 signaling and abolishes the immunosuppressive function of Treg for the treatment of cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2340.

Abstract 2649: Discovery of a potent, selective, and tumor-suppressing antibody antagonist of DKK1

Abstract Wnt signaling plays an important role in embryonic development and tumorigenesis. These biological effects are exerted by activation of the β-catenin/TCF transcription complex and consequent regulation of a set of downstream genes. Dickkopf WNT Signaling Pathway Inhibitor 1 (DKK1) has been shown to be a potent inhibitor of Wnt signaling via competing Wnt binding to LRP5/6. DKK1 is tumorigenic in multiple cancer types and also immunosuppressive via MDSCs and NK cells. Emerging evidence indicates that DKK1 has been involved in T cell differentiation and induction of cancer evasion of immune surveillance by accumulating MDSCs. Consequently, DKK1 has become a promising target for cancer immunotherapy, and the mechanisms of DKK1 affecting cancers and immune cells have received great attention. With Twist’s precision DNA writing technologies, we have created phage display libraries with diversity greater than 1 × 1010, and utilized machine learning model for optimal discovery. In this study, we discovered anti-DKK1 antibodies blocking the binding of DKK1 to the receptor. The in vitro functional assays showed that the interaction of Wnt to its receptor was restored in the presence of anti-DKK1 antibodies, resulting in TCF/LEF signaling upregulation. Moreover, anti-DKK1 antibodies induced immune cell activation, and led to tumor cell cytotoxicity. In addition, anti-DKK1 antibodies binding to different domains of DKK1 led to different functional effect. In vivo study indicated anti-DKK1 antibodies is potent in tumor regression. Our anti-DKK1 leads shows promising efficacy in cancer immunotherapy. Citation Format: Linya Wang, Sean M. Peterson, Ana Lujan, Kara Y. Chan, Cameron F. Hu, Mouna Villalta, Tom Z. Yuan, Zhen Han, Marisa Yang, Vishwas Prabhu, Tammy Htoy, Paul VanDyke, Carson Holliday, Hector Franco, Hansika Wadhwa, Hoa Giang, Ryan Stafford, Fumiko Axelrod, Aaron Sato. Discovery of a potent, selective, and tumor-suppressing antibody antagonist of DKK1 [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 2649.

Abstract 6435: BCG008, a human Siglec-15 blocking antibody, displays potent anti-tumor activity in Siglec-15-humanized mice

Abstract Sialic acid-binding Ig-like lectin 15, or Siglec-15, is identified as a critical immune suppressor. Siglec-15 expression is normally limited to certain myeloid cells, but it can be upregulated in a variety of tumors and on tumor-infiltrating myeloid cells. Siglec-15 significantly inhibits antigen-specific T cell responses both in vitro and in vivo. Conversely, genetic ablation of Siglec-15 promotes anti-tumor responses. Therefore, a Siglec-15-targeting blocking antibody could represent a novel class of anti-tumor immunotherapy. BCG008, a fully human monoclonal antibody antagonist of Siglec-15, was generated from RenMab™ mice, which contain the entire human immunoglobulin variable domain. Compared to a reference Siglec-15 blocking antibody (5G12), BCG008 exhibited higher affinity for human and cynomolgus monkey Siglec-15 and targeted distinct binding epitopes. In in vitro studies, BCG008 significantly abrogated Siglec-15-mediated T cell suppression in a dose-dependent manner, as measured by CD4+ and CD8+ T cell proliferation. Subsequently, the efficacy and safety of BCG008 was evaluated in syngeneic tumor models in Siglec15-humanized mice. BCG008 monotherapy significantly inhibited tumor growth, and the effect of the tumor inhibition was potentiated when administered in combination with other immune-checkpoint inhibitors, including anti-PD-L1 antibodies. In safety evaluation, BCG008 was well-tolerated in the tumor-bearing mice; no adverse effects were observed even at high doses (e.g. 30 mg/kg). Taken together, these results demonstrate that BCG008 is a novel anti-human Siglec-15 blocking antibody with favorable efficacy and safety profiles that can provide potential benefits for future cancer immunotherapy. Citation Format: Yongfei Yang, Aidong Qu, Fengping Yao, Pan Song, Hongyuan Liang, Maopeng Tian, Fang Yang, Zhaoxue Yu, Xu Zhou, Xiuling Li. BCG008, a human Siglec-15 blocking antibody, displays potent anti-tumor activity in Siglec-15-humanized mice [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 6435.

BYON4228 is a pan-allelic antagonistic SIRPα antibody that potentiates destruction of antibody-opsonized tumor cells and lacks binding to SIRPγ on T cells

BackgroundPreclinical studies have firmly established the CD47-signal-regulatory protein (SIRP)α axis as a myeloid immune checkpoint in cancer, and this is corroborated by available evidence from the first clinical studies with...

Advances in the CD40-mediated Manipulation Strategies

ABSTRACT: Immune homeostasis is crucial in a normal physiological, diseased, or pathogenic state and is mediated by numerous biological molecules. Certain pairs of costimulatory molecules, such as CD40-CD154 play major roles in many different situations. The functions of CD40-CD154 are pivotal for the maintenance of the immune system, cancer prevention, promotion of autoimmune disorders, and fighting against many pathogens. Since the discovery of CD40-CD154, numerous approaches have been taken to dissect this pathway favoring the interest of the host. Ranging from generating small peptides to mutated CD40L to agonistic or antagonistic antibodies have been tested in different models with varying levels of success. This review focuses on the various strategies that have been employed to manipulate CD40-CD154 dyad. Comprehensive knowledge of the understanding of different manipulation strategies of the CD40-CD154 pathway could be important for therapeutic purposes.

The IgV domain of the poliovirus receptor alone is immunosuppressive and binds to its receptors with comparable affinity

PVR (poliovirus receptor) functions as a ligand that signals through TIGIT and CD96 to induce suppression of T-cell and NK-cell responses. Alternatively, PVR binds to CD226, resulting in a co-stimulatory signal. To date, TIGIT antibody antagonists have been developed to restore immune functions and allow PVR to signal though CD226 in the context of cancer immunotherapy. Due to PVR receptor heterogeneity, agonizing either of these pathways with a recombinant form of the PVR extracellular domain represents a therapeutic strategy for either immunosuppression or activation. Here, we developed a minimal murine PVR-Fc fusion construct, consisting of only the IgV domain of PVR (vdPVR-Fc), and assessed its ability to dampen inflammatory responses in a murine model of psoriasis. vdPVR-Fc and PVR-Fc containing the full-length extracellular domain bound to TIGIT, CD96 and CD226 with similar low nanomolar affinities as defined by surface plasmon resonance. vdPVR-Fc was also able to suppress the in-vitro proliferation of murine CD4+ and CD8+ T-cells in mixed splenocyte cultures. Importantly, vdPVR-Fc delayed the onset, and reduced inflammatory responses (scaling and thickness) in a murine model of psoriasis. Collectively, our results suggest that the minimal IgV domain of PVR is sufficient to dampen immune responses in-vitro and attenuate symptoms of psoriasis in-vivo.

Nerve growth factor promotes differentiation and protects the oligodendrocyte precursor cells from in vitro hypoxia/ischemia.

Nerve growth factor (NGF) is a pleiotropic molecule acting on different cell types in physiological and pathological conditions. However, the effect of NGF on the survival, differentiation and maturation of oligodendrocyte precursor cells (OPCs) and oligodendrocytes (OLs), the cells responsible for myelin formation, turnover, and repair in the central nervous system (CNS), is still poorly understood and heavily debated. Here we used mixed neural stem cell (NSC)-derived OPC/astrocyte cultures to clarify the role of NGF throughout the entire process of OL differentiation and investigate its putative role in OPC protection under pathological conditions. We first showed that the gene expression of all the neurotrophin receptors (TrkA, TrkB, TrkC, and p75NTR ) dynamically changes during the differentiation. However, only TrkA and p75NTR expression depends on T3-differentiation induction, as Ngf gene expression induction and protein secretion in the culture medium. Moreover, in the mixed culture, astrocytes are the main producer of NGF protein, and OPCs express both TrkA and p75NTR . NGF treatment increases the percentage of mature OLs, while NGF blocking by neutralizing antibody and TRKA antagonist impairs OPC differentiation. Moreover, both NGF exposure and astrocyte-conditioned medium protect OPCs exposed to oxygenglucose deprivation (OGD) from cell death and NGF induces an increase of AKT/pAKT levels in OPCs nuclei by TRKA activation. This study demonstrated that NGF is implicated in OPC differentiation, maturation, and protection in the presence of metabolic challenges, also suggesting implications for the treatment of demyelinating lesions and diseases.

Agonistic and antagonistic targeting of immune checkpoint molecules differentially regulate osteoclastogenesis.

Immune checkpoint inhibitors are used in the treatment of various cancers and have been extensively researched with regard to inflammatory and autoimmune diseases. However, this revolutionary therapeutic strategy often provokes critical auto-inflammatory adverse events, such as inflammatory reactions affecting the cardiovascular, gastrointestinal, nervous, and skeletal systems. Because the function of these immunomodulatory co-receptors is highly cell-type specific and the role of macrophages as osteoclast precursors is widely published, we aimed to analyze the effect of immune checkpoint inhibitors on these bone-resorbing cells. We established an in vitro model of osteoclastogenesis using human peripheral blood mononuclear cells, to which various immune checkpoints and corresponding antagonistic antibodies were administered. Formation of osteoclasts was quantified and cell morphology was analyzed via immunofluorescence staining, cell size measurements, and calculation of cell numbers in a multitude of samples. These methodical approaches for osteoclast research achieved objective, comparable, and reproducible results despite the great heterogeneity in the form, size, and number of osteoclasts. In addition to the standardization of experimental analyses involving osteoclasts, our study has revealed the substantial effects of agonistic and antagonistic checkpoint modulation on osteoclastogenesis, confirming the importance of immune checkpoints in bone homeostasis. Our work will enable more robust and reproducible investigations into the use of immune checkpoint inhibitors in conditions with diminished bone density such as osteoporosis, aseptic loosening of endoprostheses, cancer, as well as the side effects of cancer therapy, and might even pave the way for novel individualized diagnostic and therapeutic strategies.

Hierarchical ensembles of FeCo metal-organic frameworks reinforced nickel foam as an impedimetric sensor for detection of IL-1RA in human samples

Early surveillance of oral cancer demands utmost concern owing to its alarming prevalence in the modern world. An efficient electrochemical impedimetric immunosensor is fabricated based on bimetallic amino-functionalized FeCo metal–organic frameworks uniformly grown on porous nickel foam solid supports (FeCo-MOF/NF) as a transducer for the detection of oral squamous cell carcinoma (OSCC). Herein, the interleukin-1 receptor antagonist (IL-1RA) antibody is used as a biorecognition element for the first time in the determination of oral cancer in real human blood samples using electrochemical impedance spectroscopy (EIS). Furthermore, the presence of specific functional groups ensures selectivity and rapid sensitivity against the target analyte IL-1RA when compared to the other biomarkers including interleukin-6 (IL-6), interleukin-8 (IL-8), CYFRA 21-1, and so on. The immunosensor shows a wide linear dynamic detection range of IL-1RA (10 fg/mL to 10 ng/mL) with a limit of detection (LOD) of 7.30 fg/mL in buffer and 7.22 fg/mL in serum conditions and a limit of quantification (LOQ) of 22.14 fg/mL in PBS and 21.88 fg/mL in serum. For a real-life demonstration, IL-1RA in human samples is detected by the immunosensor for the first time and compared with the gold standard method. The immunosensor also displays an excellent correlation with the standard detection of IL-1RA in human samples. Altogether, this work demonstrates that the electrochemical immunosensor has a high clinical significance by being a promising alternative to conventional approaches.

At the crossroads of immunotherapy for oncogene-addicted subsets of NSCLC.

Non-small-cell lung cancer (NSCLC) has become a paradigm of precision medicine, with the discovery of numerous disease subtypes defined by specific oncogenic driver mutations leading to the development of a range of molecularly targeted therapies. Over the past decade, rapid progress has also been made in the development of immune-checkpoint inhibitors (ICIs), especially antagonistic antibodies targeting the PD-L1-PD-1 axis, for the treatment of NSCLC. Although many of the major oncogenic drivers of NSCLC are associated with intrinsic resistance to ICIs, patients with certain oncogene-driven subtypes of the disease that are highly responsive to specific targeted therapies might also derive benefit from immunotherapy. However, the development of effective immunotherapy approaches for oncogene-addicted NSCLC has been challenged by a lack of predictive biomarkers for patient selection and limited knowledge of how ICIs and oncogene-directed targeted therapies should be combined. Therefore, whether ICIs alone or with chemotherapy or even in combination with molecularly targeted agents would offer comparable benefit in the context of selected oncogenic driver alterations to that observed in the general unselected NSCLC population remains an open question. In this Review, we discuss the effects of oncogenic driver mutations on the efficacy of ICIs and the immune tumour microenvironment as well as the potential vulnerabilities that could be exploited to overcome the challenges of immunotherapy for oncogene-addicted NSCLC.

Prolactin receptor signaling: A novel target for cancer treatment - Exploring anti-PRLR signaling strategies.

Prolactin (PRL) is a peptide hormone mainly secreted from the anterior pituitary gland. PRL is reported to play a role in pregnancy, mammary gland development, immune modulation, reproduction, and differentiation of islet cells. PRL binds to its receptor PRLR, which belongs to a superfamily of the class I cytokine receptor that has no intrinsic kinase activity. In canonical signaling, PRL binding to PRLR induces downstream signaling including JAK-STAT, AKT and MAPK pathways. This leads to increased cell proliferation, stemness, migration, apoptosis inhibition, and resistance to chemotherapy. PRL-signaling is upregulated in numerous hormone-dependent cancers including breast, prostate, ovarian, and endometrial cancer. However, more recently, the pathway has been reported to play a tumor-promoting role in other cancer types such as colon, pancreas, and hepatocellular cancers. Hence, the signaling pathway is an attractive target for drug development with blockade of the receptor being a potential therapeutic approach. Different strategies have been developed to target this receptor including modification of PRL peptides (Del1-9-G129R-hPRL, G129R-Prl), growth hormone receptor/prolactin receptor bispecific antibody antagonist, neutralizing antibody LFA102, an antibody-drug conjugate (ABBV-176) of the humanized antibody h16f (PR-1594804) and pyrrolobenzodiazepine dimer, a bispecific antibody targeting both PRLR and CD3, an in vivo half-life extended fusion protein containing PRLR antagonist PrlRA and albumin binding domain. There have also been attempts to discover and develop small molecular inhibitors targeting PRLR. Recently, using structure-based virtual screening, we identified a few antipsychotic drugs including penfluridol as a molecule that inhibits PRL-signaling to inhibit PDAC tumor progression. In this review, we will summarize the recent advances in the biology of this receptor in cancer and give an account of PRLR antagonist development for the treatment of cancer.

Functional Analysis of a Novel Complement C5a Receptor 1-Blocking Monoclonal Antibody

Introduction: The complement system anaphylatoxin C5a is a critical player in inflammation. By binding to complement C5a receptor 1 (C5aR1/CD88), C5a regulates many cellular functions, mainly as a potent pro-inflammatory inducer. We describe the generation and selection of a potent antagonistic C5aR1 mouse monoclonal antibody (mAb). Methods: Initial C5aR1 hybridoma clone selection was performed with a cell-binding study in human whole blood. In-house C5aR1 mAb assessment for C5aR1 inhibition was done via the iLite® C5a assay. C5aR1 mAb specificity was investigated on C5aR1his- and C5aR2his-expressing Flp-In™-CHO cells. Physiological C5aR1 inhibition was assessed via a C5a-driven calcium flux assay and stimulation assay based on isolated polymorphonuclear leukocytes (PMNs) and a whole blood model stimulated with Escherichia coli. Results: The supernatant of hybridoma clones targeting the N-terminal section of C5aR1 displayed efficient binding to C5aR1 in whole blood, which was confirmed for purified mAbs. The C5aR1 mAb 18-41-6 was selected following the assay of in-house C5aR1 mAbs via the iLite® C5a assay. The mAb 18-41-6 was specific for C5aR1. Full-size and/or F(ab’)2 preparations of mAb 18-41-6 were found to efficiently abrogate C5a-induced calcium flux in neutrophils and to significantly reduce the upregulation of the activation markers CD11b (neutrophils, monocytes) and CD66b (neutrophils). Conclusion: Our results demonstrate that mAb 18-41-6 is a valuable tool for investigating the C5a-C5aR1 axis and a potential therapeutic candidate for inflammatory disease treatment.