Target For Cancer Immunotherapy Research Articles

Abstract A017: The FES tyrosine kinase as an emerging target for cancer immunotherapy

Abstract Immunotherapies are a promising emerging pillar of cancer treatment, but they still face many barriers due to the immunosuppressive nature of cancer. Cancer immunotherapy relies on the interplay between innate and adaptive immune responses. One way of stimulating such responses, known as immunogenic cell death (ICD), involves the release of tumour-associated antigens and damage associated molecular patterns (DAMPs). These DAMPs function to recruit and activate innate immune cells, including antigen-presenting cells (APCs), through engagement of pattern recognition receptors (PRRs), subsequently leading to production of the pro-inflammatory Signal 3 cytokines required for activation of adaptive immune cells (e.g., cytotoxic T lymphocytes [CTLs] and natural killer [NK] cells). The tyrosine kinase Fes suppresses innate immune responses in APCs by inhibiting components of the PRR signaling cascade. In non-cancer contexts, the negative regulation of APCs by Fes may guard against consequences of overactive innate immunity, including endotoxic shock or autoimmune disease. However, this same inhibitory effect on APC function may also serve as a checkpoint to successful anti-cancer immunotherapy, by obstructing efficient priming of cancer specific CTLs by APCs. Therefore, by inhibiting Fes, we hypothesize there will be greater Signal 3 cytokine production, resulting in greater CTL activation, and therefore improved tumor control. Using bone marrow derived APCs, including macrophages (BMDMs) and dendritic cells (BMDCs), from wildtype (WT) or Fes knockout (fes-/-) mice, we have shown through both Western blotting and flow cytometry analysis, that PRR signal transduction cascades are suppressed by Fes and increase levels of Signal 3 cytokines produced by fes-/- APCs. This includes higher levels of cell associated IL-12 in fes-/- APCs. Using syngeneic orthotopic mouse engraftment models of triple negative breast cancer (EO771) and melanoma (B16-F10) we showed that treatment with doxorubicin (which induces ICD) or anti-PD-1 (immune checkpoint inhibitor) plus doxorubicin controls tumor growth and prolongs survival to a greater extent in fes-/- mice. Immunophenotyping of tumors and spleens from these mice showed higher levels of activated CTLs and skewing of macrophages to a M1 state in fes-/- mice. SIINFEKL peptide loaded-BMDM/BMDCs from fes-/- mice were also more effective at priming CTLs from OT-1 mice (which express a T cell receptor that recognizes the SIINFEKL peptide) in antigen cross-presentation co-culture assays. These results implicate Fes as a potential novel immune checkpoint whose inhibition may enhance anti-cancer immunotherapy by suppressing its role in dampening inflammatory Signal 3 cytokine production by APCs. I will present recent data exploring the role of Fes in regulating the expression and trafficking of IL-12 in APCs to better understand the molecular basis of improved CTL activation by fes-/- APCs. Citation Format: Julian Simonetti, Brian J. Laight, Natasha Dmytryk, Danielle Harper, Yan Gao, Changnian Shi, Madhuri Koti, Sameh Basta, Peter A. Greer. The FES tyrosine kinase as an emerging target for cancer immunotherapy [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Optimizing Therapeutic Efficacy and Tolerability through Cancer Chemistry; 2024 Dec 9-11; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(12_Suppl):Abstract nr A017.

Siglec15 in blood system diseases: from bench to bedside

Inhibiting the PD-1/PD-L1 pathway using immunomodulators has demonstrated promising outcomes in clinics. Immunomodulators can effectively target immune checkpoints with a strong preference for the tumor microenvironment (TME). Besides, immunomodulators specifically target the recently discovered inhibitory immune checkpoint, sialic acid-binding immunoglobulin-like lectin (Siglec-15). Distinctive in its molecular composition, Siglec-15 has a unique molecular composition and been shown to be highly prevalent in numerous solid tumor tissues and tumor-associated macrophages (TAMs) in human subjects. Notably, Siglec-15 is up-regulated across various cancer types. As a result, Siglec-15 has attracted significant attention due to its exclusive nature concerning PD-L1 expression, suggesting its role in immune evasion in patients lacking PD-L1. Siglec-15 predominantly appears in certain populations and can promote tumor development by repressing T lymphocyte activation and proliferation, thereby facilitating tumor cell immune escape. Furthermore, Siglec-15 is implicated in osteoclast differentiation and bone remodeling, indicating that it is a promising target for next-generation cancer immunotherapies. Additionally, Siglec-15 can modulate immune responses to microbial infections. The current treatment strategies for hematological conditions predominantly include conventional intensive chemotherapy and transplantation methods. However, emerging immunotherapeutic approaches are increasingly recognized for their overall effectiveness, indicating that specific molecular targets should be identified. The expression of Siglec-15 within tumor cells may indicate a novel pathway for treating hematological malignancies. In this study, the biological attributes, expression patterns, and pathogenic mechanisms of Siglec-15 across various diseases were reviewed. The role of Siglec-15 in the pathogenesis and laboratory diagnosis of hematological disorders was also evaluated.

Mechanisms of Cbl-Mediated Ubiquitination of Proteins in T and Natural Killer Cells and Effects on Immune Cell Functions

Post-translational ubiquitination is an essential mechanism for the regulation of protein stability and function, which contributes to the regulation of the immune system. Cbl, an E3 ubiquitin ligase, is particularly well-characterized in the context of T and NK cell signaling, where it serves as a key regulator of receptor downstream signaling events and as a modulator of cell activation. Cbl promotes the proteasomal degradation of TCR/CD3 subunits as well as the protein kinases Fyn and Lck in T cells. Additionally, the scaffold protein linker for activation of T cells (LAT) is a universal target for Cbl-mediated ubiquitination and degradation in both T and NK cells. Recent findings suggest that CrkII-mediated ubiquitination and degradation of C3G by Cbl during early T cell activation may also be relevant to NK cell signaling. Given its role in modulating immune responses and its manageable impact on autoimmunity, Cbl is being investigated as a target for cancer immunotherapy. This review explores the ubiquitin ligase activity of Cbl and its implications for CAR T and NK cell immunotherapies.

Endogenous retroviruses: unveiling new targets for cancer immunotherapy.

Endogenous retroviruses: unveiling new targets for cancer immunotherapy.

PD-L1 antibody conjugated dihydrotanshinone I-loaded polymeric nanoparticle for targeted cancer immunotherapy combining PD-L1 blockade with immunogenic cell death

PurposeCombination immune checkpoint inhibitors (ICI) with chemotherapeutic agents has proven to be highly promising in cancer therapy. However, low response rate, immune-related adverse events, and lack of effectively targeted co-delivery strategy are still major hurdles to overcome for this combination therapeutic regimen. Herein, programmed death-L1 (PD-L1) antibody modified and dihydrotanshinone I (DHT) loaded nanoparticle was prepared for tumor targeting drug delivery, thus achieving immune checkpoint blockade (ICB) and immunogenic cell death (ICD) synergistic anti-tumor effects. MethodsThe DHT-loaded nanoparticle (DHT NP) was prepared by the emulsion solvent diffusion method. Atezolizumab (ATEZO) was thiolated with 2-iminothiolane and conjugated to the surface of DHT NP to prepare the ATEZO DHT NP. The drug encapsulation efficiency, drug loading, particle size and drug release were determined. The in vitro cellular uptake, cell proliferation inhibition and apoptosis were evaluated on the HGC-27 tumor cell. The in vivo tumor targeting, anti-tumor efficiency and immune regulation were assessed on tumor bearing mice. ResultsThe optimized ATEZO DHT NP was a spherical nanoparticle of about 250 nm with a continuous drug release profile. It was selectively taken up by the tumor cells through PD-L1 receptor-mediated endocytosis, which resulted in enhanced cytotoxicity and cell apoptosis. In vivo imaging further demonstrated its superior tumor tissue targeting ability. When tumor bearing mice were treated with the ATEZO DHT NP, its synergistic anti-tumor effect was much stronger than that of a single drug. Moreover, the tumor targeting delivery of DHT caused tumor necrosis and initiated ICD with release of tumor-associated antigens, which efficiently up-regulated the population of CD4+ and CD8+ T cells. Notably, there were no obvious system toxicity or tissue damage occur during the whole treatment period. ConclusionThe ATEZO DHT NP could specifically target to tumor and enhance treatment efficiency through combination of PD-L1 blockade with ICD effect.

RNA N6-Methyladenosine-Binding Protein YTHDFs Redundantly Attenuate Cancer Immunity by Downregulating IFN-γ Signaling in Gastric Cancer.

Immunotherapy holds potential as a treatment for gastric cancer (GC), though immune checkpoint inhibitor (ICI) resistance remains an obstacle. One resistance mechanism involves defects in interferon-γ (IFN-γ) signaling, in which IFN-γ is linked to improved responsiveness to ICIs. Herein, the roles of RNA N6-methyladenosine (m6A) modifications in regulation of IFN-γ signaling and the responsiveness to ICIs are unveiled. The m6A-binding protein YTH N6-methyladenosine RNA-binding protein F1 (YTHDF1) is overexpressed in GC tissues, correlating with the suppression of cancer immunity and poorer survival rates. YTHDF1 overexpression impaired the responsiveness to IFN-γ in GC cells, and knockdown studies indicated the redundant effects of YTHDF2 and YTHDF3 with YTHDF1 in IFN-γ responsiveness. RNA immunoprecipitation sequencing revealed YTHDFs directly target interferon regulatory factor 1 (IRF1) mRNA, a master regulator of IFN-γ signaling, leading to reduced RNA stability and consequent downregulation of IFN-γ signaling. Furthermore, in mouse syngeneic tumor models, Ythdf1 depletion in cancer cells resulted in reduced tumor growth and increased tumor-infiltrating lymphocytes, which are attributed to the augmentation of IFN-γ signaling. Collectively, these findings highlight how YTHDFs modulate cancer immunity by influencing IFN-γ signaling through IRF1 regulation, suggesting their viability as therapeutic targets in cancer immunotherapy.

Emerging Role of Extracellular pH in Tumor Microenvironment as a Therapeutic Target for Cancer Immunotherapy.

Identifying definitive biomarkers that predict clinical response and resistance to immunotherapy remains a critical challenge. One emerging factor is extracellular acidosis in the tumor microenvironment (TME), which significantly impairs immune cell function and contributes to immunotherapy failure. However, acidic conditions in the TME disrupt the interaction between cancer and immune cells, driving tumor-infiltrating T cells and NK cells into an inactivated, anergic state. Simultaneously, acidosis promotes the recruitment and activation of immunosuppressive cells, such as myeloid-derived suppressor cells and regulatory T cells (Tregs). Notably, tumor acidity enhances exosome release from Tregs, further amplifying immunosuppression. Tumor acidity thus acts as a "protective shield," neutralizing anti-tumor immune responses and transforming immune cells into pro-tumor allies. Therefore, targeting lactate metabolism has emerged as a promising strategy to overcome this barrier, with approaches including buffer agents to neutralize acidic pH and inhibitors to block lactate production or transport, thereby restoring immune cell efficacy in the TME. Recent discoveries have identified genes involved in extracellular pH (pHe) regulation, presenting new therapeutic targets. Moreover, ongoing research aims to elucidate the molecular mechanisms driving extracellular acidification and to develop treatments that modulate pH levels to enhance immunotherapy outcomes. Additionally, future clinical studies are crucial to validate the safety and efficacy of pHe-targeted therapies in cancer patients. Thus, this review explores the regulation of pHe in the TME and its potential role in improving cancer immunotherapy.

A Quest for the Dual Role of Lymphatic Transport in Cancer: From Immune Surveillance to Tumour Dissemination

Background: Lymphatic transport is indispensable for maintaining tissue homeostasis and orchestrating immune surveillance. However, its association with solid tumor development and dissemination poses a paradox. While initially perceived as a passive conduit for metastasis, recent research highlights the active involvement of lymphatic vessels in tumor progression, inflammation, and immune surveillance. Objective: This study aims to elucidate the active mechanisms underlying lymphatic transport's contribution to peripheral tissue immunity and its dual role in tumor-associated immune responses. Additionally, it explores emerging areas of interest in targeted cancer immunotherapy. Methods: A comprehensive literature review was conducted to gather insights into the role of lymphatic transport in both physiological and pathological contexts, with a focus on cancer progression and immune modulation. Relevant studies and reviews were analyzed to provide current understanding and identify future directions in cancer immunotherapy. Results: Lymphatic vessels actively shape their transport function to influence peripheral tissue immunity, facilitating immune cell trafficking and antigen drainage. However, tumor-associated lymphatic remodeling disrupts this balance, promoting tumor dissemination and fostering a protumorigenic microenvironment. Emerging research implicates lymphatic vessels in the formation of tertiary lymphoid structures, immune surveillance in the central nervous system, and interactions with the microbiome, obesity, and aging, highlighting their multifaceted role in cancer immunity. Conclusion: Insights gained in lymphatic biology offer promising avenues for enhancing cancer immunotherapy by targeting lymphatic vessels and their transport function. A comprehensive understanding of lymphatic involvement in cancer pathogenesis supports its integration into therapeutic strategies to optimize immune surveillance and improve patient outcomes.

A Computational Approach to Characterize the Protein S-Mer Tyrosine Kinase (PROS1-MERTK) Protein-Protein Interaction Dynamics.

Protein S (PROS1) has recently been identified as a ligand for the TAM receptor MERTK, influencing immune response and cell survival. The PROS1-MERTK interaction plays a role in cancer progression, promoting immune evasion and metastasis in multiple cancers by fostering a tumor-supportive microenvironment. Despite its importance, limited structural insights into this interaction underscore the need for computational studies to explore their binding dynamics, potentially guiding targeted therapies. In this study, we investigated the PROS1-MERTK interaction using advanced computational analyses to support immunotherapy research. High-resolution structural models from ColabFold, an AlphaFold2 adaptation, provided a baseline structure, allowing us to examine the PROS1-MERTK interface with ChimeraX and map residue interactions through Van der Waals criteria. Molecular dynamics (MD) simulations were conducted in GROMACS over 100 ns to assess stability and conformational changes using RMSD, RMSF, and radius of gyration (Rg). The PROS1-MERTK interface was predicted to contain a heterogeneous mix of amino acid contacts, with lysine and leucine as frequent participants. MD simulations demonstrated prominent early structural shifts, stabilizing after approximately 50 ns with small conformational shifts occurring as the simulation completed. In addition, there are various regions in each protein that are predicted to have greater conformational fluctuations as compared to others, which may represent attractive areas to target to halt the progression of the interaction. These insights deepen our understanding of the PROS1-MERTK interaction role in immune modulation and tumor progression, unveiling potential targets for cancer immunotherapy.

Injectable microgels containing genetically engineered bacteria for colon cancer therapy through programmed Chemokine expression

Chemokines are emerging as important targets for cancer immunotherapy due to their role in regulating immune cell migration and activation within the tumor microenvironment. Effective delivery and sustained presence of chemokines at the tumor site is essential for recruiting and activating immune cells to exert anti-tumor effects. In this study, we report a genetically engineered bacterial cell factory designed for the continuous production of chemokine CCL21 in a controlled manner. To decrease the formation of infusion bodies (IBs) in bacteria, we used thioredoxin (Trx) as the fusion partner and cloned at N-terminal of the target protein. The commonly used promoters, pT7-LacO, pBV220, and pDawn, were employed to explore the influence of various inducers on the expression of CCL21 in bacteria. The engineered bacteria were finally encapsulated within spherical gelatin methacryloyl (GelMA) microgels, which not only maintained bacterial viability but also prolonged their retention in the intestines of mice. As a result, the sustained presence and localized production of CCL21 led to effective suppression of tumor growth.

Synthetic Nanocapsules with Tailored Surface Chemistry for Lung-Specific Protein Delivery and Cancer Immunotherapy.

Efficient delivery of therapeutic proteins remains a major challenge in developing effective immunotherapies and treatments for genetic disorders due to the limited tissue targeting capability of native proteins. In this study, the design and synthesis of protein nanocapsules (NCs) that achieve lung-specific delivery of therapeutic proteins are reported. These NCs are synthesized through a surface modification process that involves coating protein with functional monomers and cross-linkers, followed by in situ polymerization to create a protective shell on the protein surface with tailored surface chemistry. This approach preserves protein integrity and significantly enhances delivery efficiency and tissue specificity. Notably, it is shown that protein@NC with guanidine-rich surfaces exhibit exceptional lung-targeting capabilities. This is likely attributed to the formation of a vitronectin-rich protein corona, which facilitates receptor-mediated endocytosis by lung cells. The platform effectively delivers various proteins, such as ovalbumin, to antigen-presenting cells (APCs) in the lung, thereby enhancing antigen presentation and offering a promising strategy for cancer immunotherapy. These findings provide a significant advancement in tissue-specific protein delivery and hold the potential for targeted cancer immunotherapy.

CWF19L1 promotes T-cell cytotoxicity through the regulation of alternative splicing

Enhancing host anti-tumor immunity is paramount for advancing cancer immunotherapy. In this study, we identify CWF19-like cell cycle control factor 1 (CWF19L1) as a novel splicing regulator that enhances T cell-mediated cytotoxicity. CWF19L1 interacts prominently with key splicing factors within the nucleus, including components of the U5 small nuclear ribonucleoprotein (snRNP) and the pre-mRNA processing factor 19 (PRPF19) complex. Deficiency of CWF19L1 disrupts alternative splicing of immune-related genes, resulting in diminished expression of cytotoxic molecules. Furthermore, CWF19L1 plays a critical role in promoting T cell-mediated anti-tumor responses by upregulating the expression of effector cytokines. Our findings unveil previously undocumented functions of CWF19L1 in alternative splicing and its involvement in the regulation of anti-tumor immunity, highlighting its potential as a therapeutic target for novel cancer immunotherapies.

Next Generation of Solid Target Radionuclide Antibody Conjugates for Tumor Immuno-Therapy.

Immune checkpoint therapy has emerged as an effective treatment option for various types of cancers. Key immune checkpoint molecules, such as cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), programmed cell death protein 1 (PD-1), and lymphocyte activation gene 3 (LAG-3), have become pivotal targets in cancer immunotherapy. Antibodies designed to inhibit these molecules have demonstrated significant clinical efficacy. Nevertheless, the ability to monitor changes in the immune status of tumors and predict treatment response remains limited. Conventional methods, such as assessing lymphocytes in peripheral blood or conducting tumor biopsies, are inadequate for providing real-time, spatial information about T-cell distributions within heterogeneous tumors. Positron emission tomography (PET) using T-cell specific probes represents a promising and noninvasive approach to monitor both systemic and intratumoral immune changes during treatment. This technique holds substantial clinical significance and potential utility. In this paper, we review the applications of PET probes that target immune cells in molecular imaging.

Characterizing dynamic tumor-immune interactions in lung adenocarcinoma through orthotopic allograft modeling.

The major clinical challenge in lung cancer immunotherapy is drug resistance. Therefore, establishing efficient orthotopic lung cancer mouse models to explore the mechanisms of drug immunotherapy resistance is highly important. In this study, we generated multiple fluorescently labeled lung adenocarcinoma cell lines from agenetically engineered KPZ mice model. Orthotopic transplantation of the primary 1F3 cell line induced a strong immune response, causing many small tumors to disappear, but some tumors evaded the immune attack and eventually formed large tumors. Tumor microenvironment analysis demonstrated that M2 macrophages play key roles in the immune response. Further mechanistic studies revealed that the chemokine CCL7 promoted the infiltration of M2 macrophages to facilitate immune escape, thereby promoting tumor growth in the orthotopic mouse model. Moreover, CCL7 levels were elevated in human lung cancer biopsies and positively correlated with M2 macrophage infiltration, and high CCL7 levels predicted advanced pathological stage and poor survival in lung cancer patients. Overall, we established a visualized and orthotopic mouse model with fluorescently labeled cells to better dissect the tumor microenvironment of lung cancer and define the critical role of CCL7 in promoting M2 macrophage polarization and tumorigenesis, providing new preclinical tools and potential targets for lung cancer immunotherapy.

Development of a PD-L1 Overexpression System in HEK293T Cells: A Platform for Studying Immune Evasion Mechanisms

Programmed death-ligand 1 (PD-L1) is a key immune checkpoint protein that facilitates tumor immune evasion by interacting with PD-1 receptors on T cells, making the PD-1/PD-L1 axis a critical target in cancer immunotherapy. However, resistance to these therapies remains a challenge, necessitating further exploration of PD-L1’s functions and regulatory mechanisms. In this study, we amplified the PD-L1 coding sequence (CDS) from human cDNA, cloned it into a pcDNA3.1 vector, and transfected it into HEK293T cells to establish a robust in vitro PD-L1 overexpression system. Quantitative RT-qPCR demonstrated a 300-400 fold increase in PD-L1 mRNA expression compared to controls. These results confirm the successful construction of the PD-L1 overexpression plasmid and validate its application as a tool for studying PD-L1’s role in immune modulation and its potential implications in overcoming resistance to immunotherapy. This system provides a valuable platform for future investigations into PD-L1-mediated mechanisms of immune evasion and cancer progression.

Current advancements in PD-L1 modulation by CMTM6 in malignant tumors

Abstract The CKLF-like MARVEL transmembrane domain-containing protein 6 (CMTM6), a member of the chemokine-like factor superfamily, binds to programmed death-ligand 1 (PD-L1) on the cell membrane, thereby impeding PD-L1’s lysosomal degradation and sustaining its expression. In recent years, extensive studies on PD-L1 have provided insights into its function as an immunepoint inhibitor involved in tumor cell immune evasion. The specific interaction between CMTM6 and PD-L1 suggests a potential role in tumor cell immune evasion and suppression, potentially offering a novel therapeutic target for cancer immunotherapy. Currently, the research on CMTM6 and PD-L1 in diverse tumors and diseases is limited, but their significant roles are indicated. This article provides an overview of the impact of CMTM6 on the immune microenvironment in different types of cancer (such as lung cancer, breast cancer, and liver cancer), and summarizes the effects of CMTM6 on the occurrence and development of various tumors.

Clinical significance of CD155 expression in surgically resected lung squamous cell carcinoma.

Cluster of differentiation 155 (CD155) is expressed in many tumor types. CD155 is involved in the immune avoidance of tumor cells and contributes to tumor development and progression. Therefore, CD155 is a novel target for cancer immunotherapy. The clinical significance of CD155 expression in lung squamous cell carcinoma (LUSC) has not been fully elucidated. We performed a retrospective analysis of 264 patients with surgically resected LUSC. Immunohistochemistry was used to evaluate CD155 expression. The association of CD155 expression with clinicopathological features and clinical outcomes was assessed. We also analyzed the relationship between CD155 expression and programmed cell death-ligand 1 (PD-L1) expression and tumor-infiltrating lymphocytes. Among the 264 patients, 137 patients (51.9%) were classified in the high CD155 expression group. High CD155 expression was significantly associated with pleural invasion, vascular invasion, PD-L1 positivity, and high CD3, CD4, and CD8 expressions. In multivariate analysis, the presence of pleural invasion and PD-L1 positivity were independent predictors of high CD155 expression. Kaplan-Meier curve analysis showed that high CD155 expression was significantly associated with shorter disease-free survival and overall survival. In multivariate analysis, high CD155 expression was an independent poor prognostic factor for overall survival, but not for disease-free survival. Subgroup analyses revealed that the prognostic effect of CD155 expression was observed in the PD-L1 positive group but not the PD-L1 negative group. Our analysis revealed that high CD155 expression significantly predicted poor prognosis in patients with surgically resected LUSC, especially in patients with PD-L1-positive tumors.

Evaluation of STK17B as a cancer immunotherapy target utilizing highly potent and selective small molecule inhibitors.

The serine/threonine kinase 17B (STK17B) is involved in setting the threshold for T cell activation and its absence sensitizes T cells to suboptimal stimuli. Consequently, STK17B represents an attractive potential target for cancer immunotherapy. To assess the potential of STK17B as an immuno-oncology target, we developed potent and selective tool compounds from starting points in Blueprint Medicines Corporation's proprietary kinase inhibitor library. To characterize these molecules, enzyme and cellular assays for STK17A and STK17B were established to drive chemistry optimization. Mass spectrometry-based phosphoproteomics profiling with tool inhibitors led to the identification of Ser19 on myosin light chain 2 as STK17B substrate, which is then developed into a flow cytometry-based pharmacodynamic readout of STK17B inhibition both in vitro and in vivo. In a mouse T cell activation assay, STK17B inhibitors demonstrated the ability to enhance interleukin-2 (IL-2) production. Similarly, treatment with STK17B inhibitors resulted in stronger cytokine secretion in human T cells activated using a T cell bispecific antibody. Subsequent chemistry optimization led to the identification of a highly selective and orally bioavailable tool compound, BLU7482. In vivo, STK17B inhibition led to dose-dependent modulation of myosin light chain 2 phosphorylation and enhanced priming of naïve T cells, as determined by upregulation of CD69, IL-2 and interferon-γ secretion. In line with increased T cell activation, treatment with STK17B inhibitor enhanced antitumor activity of anti-PD-L1 antibody in the MCA205 model. In summary, we successfully identified and optimized STK17B kinase inhibitors which led to increased T cell responses in vitro and in vivo. This allowed us to evaluate the potential of STK17B inhibition as an approach for cancer immunotherapy.

Monoclonal antibody targeting CEACAM1 enhanced the response to anti-PD1 immunotherapy in non-small cell lung cancer

Carcinoembryonic antigen-related cellular adhesion molecule 1 (CEACAM1), an extensively studied cell surface molecule, mainly expressed by certain epithelial, endothelial, lymphoid and myeloid cells, and is an attractive target for cancer immunotherapy. Here, to investigate the anti-tumor effects and mechanisms of CEACAM1 antibody, we prepared the antibody and explored its anti-tumor effects on Non-small Cell Lung Cancer (NSCLC) in vitro and in vivo. Firstly, antigen of human CEACAM1 recombinant protein was immunized on BALB/c mice and the high-affinity mouse anti-human monoclonal antibody 3C11 was selected by hybridoma technique. Next, ELISA was applied to detect the blocking effects of 3C11 on CEACAM1-CEACAM1 and CEACAM1-CEACAM5. Then, cell assays and ELISA were used to evaluate the role of 3C11 in blocking CEACAM1-CEACAM1 immunosuppressive signal transduction between dendritic cells (DCs) and T cells or natural killer cells (NK) and tumor cells. Finally, the synergistic anti-tumor effect of 3C11 combined with anti-PD-1 antibody was evaluated through cell stimulation assays and NCI-H358-induced tumor models in mice. The results showed the EC50 of 3C11 binding to NCI-H358 or exhausted T cells were 0.04971 μg/mL and 0.03475 μg/mL, respectively. 3C11 activated the exhausted T cells and enhanced the killing effect of NK by blocking CEACAM1-CEACAM1. In addition, the combination of 3C11 and anti-PD1 antibody produced synergistic anti-tumor effect on NSCLC. Its improved tumor growth inhibition value (TGI) of anti-PD-1 from 18 % to 85 % in vivo. These findings suggest that 3C11 can be considered an effective immunotherapy drug for NSCLC.

In silico and pharmacological evaluation of GPR65 as a cancer immunotherapy target regulating T-cell functions.

The success of cancer immunotherapies such as immune checkpoint inhibitors, CAR T-cells and immune cell engagers have provided clinicians with tools to bypass some of the limitations of cancer immunity. However, numerous tumour factors curtail the immune response against cancer and limit the efficiency of immuno-oncology (IO) therapies. Acidification of the extra-cellular tumour environment consecutive to aberrant cancer cell metabolism is a well-known promoter of oncogenic processes that also acts as an immune regulator. Yet, the suppressive mechanisms of low extra-cellular pH on anti-cancer immunity remain poorly understood. Recent reports have suggested that GPR65, a Gαs-coupled proton-sensing GPCR broadly expressed in the immune system, may act as an immune suppressant detrimental to anti-tumour immunity. So far, the immuno-regulatory properties of GPR65 in acidic milieux have mostly been documented in macrophages and myeloid cells. Our computational evaluation of GPR65's transcriptomic expression profile and potential as an IO target using public datasets prompted us to further investigate its functions in human T-cells. To this end, we identified and validated GPR65 small molecule inhibitors active in in vitro cellular assays and we showed that GPR65 inhibition promoted the killing capacity of antigen-specific human T-cells. Our results broaden the scope of GPR65 as an IO target by suggesting that its inhibition may enhance T-cell anti-tumour activity and provide useful pharmacological tools to further investigate the therapeutic potential of GPR65 inhibition.