Strategy For Cancer Immunotherapy Research Articles

Abstract 5298: BSI-093, a best-in-class anti-BTN3A monoclonal antibody for cancer immunotherapy by activation of Vg9Vd2 T cells

Abstract Background: Gamma delta T (γδ T) cells are potent anti-cancer effectors with the potential to target tumors broadly, independent of patient-specific neoantigens or human leukocyte antigen background. Among tumor-infiltrating lymphocytes, the presence of γδ T cells is the most favorable prognostic marker for overall survival of patients with various solid and hematologic tumors. Vγ9Vδ2 T cells are the predominant γδ T cells in peripheral circulation. Butyrophilin 3A (BTN3A) members, widely expressed in tumors, have emerged as novel molecules modulating the function of Vγ9Vδ2 T cells. Targeting BTN3A for activation of Vγ9Vδ2 T cells provides an alternative strategy for cancer immunotherapy. Experimental procedures: BALB/c mice were immunized with recombinant BTN3A1-ECD-Fc. The Biosion proprietary H3 (High-throughput, High-content and High-efficiency) antibody discovery platform was used to identify an anti-BTN3A monoclonal antibody lead candidate - BSI-093. The target binding specificity, binding activity, and affinity of BSI-093 were evaluated by protein-based ELISA, cell-based FACS and Biacore-based SPR. Ex vivo assays were used to evaluate the cellular bioactivity of BSI-093 on activating Vγ9Vδ2 T cells for killing activity of various tumor cells. B-NDG mice bearing Jurkat-GFP-Luc tumors were used to evaluate the tumor inhibitory activity of the anti-BTN3A antibody. Summary: BSI-093 is a humanized monoclonal antibody with the following critical properties: (1) binds to all BTN3A members (BTN3A1, BTN3A2 and BTN3A3) with high affinity; (2) has potentially longer half-life and silenced Fc-effector function by Fc-engineering; (3) exhibits cross-reactivity to rhesus BTN3A members; (4) demonstrates strong activity on activating Vγ9Vδ2 T cells to kill a variety of natural cancer cells in ex vivo assays; and (5) shows significant anti-tumor efficacy in a CDX model. Conclusion: BSI-093 demonstrates potential best-in-class biophysical properties and functional characteristics, supporting the initiation of development activities including manufacturing and IND-enabling studies. Citation Format: Wenwen Dai, Jun Li, Jinyu Liu, Hongyan Li, Xiaodong F. Liu, Shukai Xia, Qun Lyu, Hugh M. Davis, Mingjiu Chen, Zeyu Peng. BSI-093, a best-in-class anti-BTN3A monoclonal antibody for cancer immunotherapy by activation of Vg9Vd2 T cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5298.

Abstract 7251: Surface-engineered extracellular vesicles to modulate antigen-specific T cell expansion for cancer immunotherapy

Abstract Tumor immunotherapy, including immune checkpoint therapy, CAR T cell therapy, and TCR-T cell therapy, has made significant progress in the treatment of cancer. Recently, newly developed nanomaterials have also been applied to anti-tumor immunotherapy. Among them, extracellular vesicles (EVs) have been well-engineered in recent years due to their low immunogenicity, high stability, and wide distribution in biological fluids. Despite the recent development of several EVs-based cancer immunotherapies, their clinical efficacy remains limited. In this study, we have developed engineered EVs designed to mimic the function of antigen-presenting cells, which can co-deliver multiple immune-activation signals to tumor-associated T cells. We named these vesicles Antigen-presenting Extracellular Vesicles (AP-EVs). AP-EVs express a high level of MHC I-peptide complexes, costimulatory molecules, and surface-bound cytokines, allowing for the simultaneous presentation of multiple immune modulators to antigen-specific CD8+ T cells. AP-EVs promote the clonal expansion and differentiation of antigen-specific cytotoxic T lymphocytes, resulting in potent anticancer immune responses. Notably, our findings indicate that combination therapy involving AP-EVs and anti-PD-1 yields superior anticancer immunity against established tumors compared to anti-PD-1 monotherapy. This synergistic effect underscores the potential of our engineered EVs as a novel and highly effective strategy for cancer immunotherapy. Citation Format: Xiabing Lyu, Tomoyoshi Yamano, Shota Imai, Toan Van Le, Rikinari Hanayama. Surface-engineered extracellular vesicles to modulate antigen-specific T cell expansion for cancer immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7251.

A Responsive DNA Hydrogel Containing Poly‐Aptamers as Dual‐Target Inhibitors for Localized Cancer Immunotherapy

AbstractImmune checkpoint blockade (ICB) is emerging as an efficient strategy for cancer immunotherapy, which highly relies on the controlled loading and release of immune checkpoints inhibitors. Herein, a responsive DNA hydrogel containing polyvalent aptamers as dual‐target inhibitors is reported to achieve ICB for localized cancer immunotherapy. This DNA hydrogel is constructed by two ultralong DNA chains generated via rolling circle amplification (RCA), which contained two polyvalent aptamers (PD‐1 and CTLA‐4 aptamers), and is loaded with inflammatory‐responsive nanoparticles that encapsulated restriction endonuclease. The DNA hydrogel achieved the specific enrichment of T cells. The restriction endonuclease is specifically released by responding to the inflammatory microenvironment, which subsequently cleaved the DNA hydrogel at the cutting sites of DNA chains. The released PD‐1 and CTLA‐4 aptamers executed the biological functions as immune checkpoint inhibitors, successfully blocking immune checkpoints to activate T cells in tumor sites; as a result, the killing efficacy toward tumor cells is significantly enhanced. In a melanoma tumor‐bearing mouse model, the DNA hydrogel activated the immune response in tumor tissues and showed notable therapeutic efficacy for the inhibition of tumor progression (≈65%). This responsive DNA hydrogel is expected to be a promising formulation for immunotherapeutic medicines.

A specific enterotype derived from gut microbiome of older individuals enables favorable responses to immune checkpoint blockade therapy

Immunotherapy has revolutionized cancer treatment, but inconsistent responses persist. Our study delves into the intriguing phenomenon of enhanced immunotherapy sensitivity in older individuals with cancers. Through a meta-analysis encompassing 25 small-to-mid-sized trials of immune checkpoint blockade (ICB), we demonstrate that older individuals exhibit heightened responsiveness to ICB therapy. To understand the underlying mechanism, we reanalyze single-cell RNA sequencing (scRNA-seq) data from multiple studies and unveil distinct upregulation of exhausted and cytotoxic Tcell markers within the tumor microenvironment (TME) of older patients. Recognizing the potential role of gut microbiota in modulating the efficacy of immunotherapy, we identify an aging-enriched enterotype linked to improved immunotherapy outcomes in older patients. Fecal microbiota transplantation experiments in mice confirm the therapeutic potential of the aging-enriched enterotype, enhancing treatment sensitivity and reshaping the TME. Our discoveries confront the prevailing paradox and provide encouraging paths for tailoring cancer immunotherapy strategies according to an individual's gut microbiome profile.

Dual-Responsive Supramolecular Polymeric Nanomedicine for Self-Cascade Amplified Cancer Immunotherapy.

Insufficient tumor immunogenicity and immune escape from tumors remain common problems in all tumor immunotherapies. Recent studies have shown that pyroptosis, a form of programmed cell death that is accompanied by immune checkpoint inhibitors, can induce effective immunogenic cell death and long-term immune activation. Therapeutic strategies to jointly induce pyroptosis and reverse immunosuppressive tumor microenvironments are promising for cancer immunotherapy. In this regard, a dual-responsive supramolecular polymeric nanomedicine (NCSNPs) to self-cascade amplify the benefits of cancer immunotherapy is designed. The NCSNPs are formulated by β-cyclodextrin coupling nitric oxide (NO) donor, a pyroptosis activator, and NLG919, an indoleamine 2,3-dioxygenase (IDO) inhibitor, and self-assembled through host-guest molecular recognition and hydrophobic interaction to obtain nanoparticles. NCSNPs possess excellent tumor accumulation and bioavailability attributed to ingenious supramolecular engineering. The study not only confirms the occurrence of NO-triggered pyroptosis in tumors for the first time but also reverses the immunosuppressive microenvironment in tumor sites via an IDO inhibitor by enhancing the infiltration of cytotoxic T lymphocytes, to achieve remarkable inhibition of tumor proliferation. Thus, this study provides a novel strategy for cancer immunotherapy.

Therapeutic approaches to enhance natural killer cell cytotoxicity.

Enhancing the cytotoxicity of natural killer (NK) cells has emerged as a promising strategy in cancer immunotherapy, due to their pivotal role in immune surveillance and tumor clearance. This literature review provides a comprehensive overview of therapeutic approaches designed to augment NK cell cytotoxicity. We analyze a wide range of strategies, including cytokine-based treatment, monoclonal antibodies, and NK cell engagers, and discuss criteria that must be considered when selecting an NK cell product to combine with these strategies. Furthermore, we discuss the challenges and limitations associated with each therapeutic strategy, as well as the potential for combination therapies to maximize NK cell cytotoxicity while minimizing adverse effects. By exploring the wealth of research on this topic, this literature review aims to provide a comprehensive resource for researchers and clinicians seeking to develop and implement novel therapeutic strategies that harness the full potential of NK cells in the fight against cancer. Enhancing NK cell cytotoxicity holds great promise in the evolving landscape of immunotherapy, and this review serves as a roadmap for understanding the current state of the field and the future directions in NK cell-based therapies.

Microfluidics-enabled fluorinated assembly of EGCG-ligands-siTOX nanoparticles for synergetic tumor cells and exhausted t cells regulation in cancer immunotherapy

Immune checkpoint inhibitor (ICI)-derived evolution offers a versatile means of developing novel immunotherapies that targets programmed death-ligand 1 (PD-L1)/programmed death-1 (PD-1) axis. However, one major challenge is T cell exhaustion, which contributes to low response rates in "cold" tumors. Herein, we introduce a fluorinated assembly system of LFNPs/siTOX complexes consisting of fluorinated EGCG (FEGCG), fluorinated aminolauric acid (LA), and fluorinated polyethylene glycol (PEG) to efficiently deliver small interfering RNA anti-TOX (thymus high mobility group box protein, TOX) for synergistic tumor cells and exhausted T cells regulation. Using a microfluidic approach, a library of LFNPs/siTOX complexes were prepared by altering the placement of the hydrophobe (LA), the surface PEGylation density, and the siTOX ratio. Among the different formulations tested, the lead formulation, LFNPs3-3/siTOX complexes, demonstrated enhanced siRNA complexation, sensitive drug release, improved stability and delivery efficacy, and acceptable biosafety. Upon administration by the intravenous injection, this formulation was able to evoke a robust immune response by inhibiting PD-L1 expression and mitigating T cell exhaustion. Overall, this study provides valuable insights into the fluorinated assembly and concomitant optimization of the EGCG-based delivery system. Furthermore, it offers a promising strategy for cancer immunotherapy, highlighting its potential in improving response rates in ‘‘cold’’ tumors.Graphical

Gentulizumab, a novel anti-CD47 antibody with potent antitumor activity and demonstrates a favorable safety profile

BackgroundTargeting CD47/SIRPα axis has emerged as a promising strategy in cancer immunotherapy. Despite the encouraging clinical efficacy observed in hematologic malignancies through CD47-SIRPα blockade, there are safety concerns related to the binding of anti-CD47 antibodies to CD47 on the membrane of peripheral blood cells.MethodsIn order to enhance the selectivity and therapeutic efficacy of the antibody, we developed a humanized anti-CD47 monoclonal antibody called Gentulizumab (GenSci059). The binding capacity of GenSci059 to CD47 was evaluated using flow cytometry and surface plasmon resonance (SPR) methods, the inhibitory effect of GenSci059 on the CD47-SIRPα interaction was evaluated through competitive ELISA assays. The anti-tumor activity of GenSci059 was assessed using in vitro macrophage models and in vivo patient-derived xenograft (PDX) models. To evaluate the safety profile of GenSci059, binding assays were conducted using blood cells. Additionally, we investigated the underlying mechanisms contributing to the weaker binding of GenSci059 to erythrocytes. Finally, toxicity studies were performed in non-human primates to assess the potential risks associated with GenSci059.ResultsGenSci059 displayed strong binding to CD47 in both human and monkey, and effectively inhibited the CD47-SIRPα interaction. With doses ranging from 5 to 20 mg/kg, GenSci059 demonstrated potent inhibition of the growth of subcutaneous tumor with the inhibition rates ranged from 30.3% to complete regression. Combination of GenSci059 with 2.5 mg/kg Rituximab at a dose of 2.5 mg/kg showed enhanced tumor inhibition compared to monotherapy, exhibiting synergistic effects. GenSci059 exhibited minimal binding to hRBCs compared to Hu5F9-G4. The binding of GenSci059 to CD47 depended on the cyclization of N-terminal pyroglutamic acid and the spatial conformation of CD47, but was not affected by its glycosylation modifications. A maximum tolerated dose (MTD) of 450 mg/kg was observed for GenSci059, and no significant adverse effects were observed in repeated dosages up to 10 + 300 mg/kg, indicating a favorable safety profile.ConclusionGenSci059 selectively binds to CD47, effectively blocks the CD47/SIRPα axis signaling pathway and enhances the phagocytosis effects of macrophages toward tumor cells. This monoclonal antibody demonstrates potent antitumor activity and exhibits a favorable safety profile, positioning it as a promising and effective therapeutic option for cancer.

DDX3 regulates cancer immune surveillance via 3′ UTR-mediated cell-surface expression of PD-L1

Programmed death-1 (PD-1)/PD ligand-1 (PD-L1)-mediated immune escape contributes to cancer development and has been targeted as an anti-cancer strategy. Here, we show that inhibition of the RNA helicase DDX3 increased CD8+ Tcell infiltration in syngeneic oral squamous cell carcinoma tumors. DDX3 knockdown compromised interferon-γ-induced PD-L1 expression and, in particular, reduced the level of cell-surface PD-L1. DDX3 promoted surface PD-L1 expression by recruiting the adaptor protein 2 (AP2) complex to the 3' UTR of PD-L1 mRNA. DDX3 depletion or 3' UTR truncation increased the binding of the coatomer protein complexes to PD-L1, leading to its intracellular accumulation. Therefore, this 3' UTR-dependent mechanism may counteract cellular negative effects on surface trafficking of PD-L1. Finally, pharmaceutic disruption of DDX3's interaction with AP2 reduced surface PD-L1 expression, supporting that the DDX3-AP2 pathway routes PD-L1 to the cell surface. Targeting DDX3 to modulate surface trafficking of immune checkpoint proteins may provide a potential strategy for cancer immunotherapy.

Network-based screening identifies sitagliptin as an antitumor drug targeting dendritic cells

BackgroundDendritic cell (DC)-mediated antigen presentation is essential for the priming and activation of tumor-specific T cells. However, few drugs that specifically manipulate DC functions are available. The identification of drugs...

An EBV-related CD4 TCR immunotherapy inhibits tumor growth in an HLA-DP5+ nasopharyngeal cancer mouse model.

Adoptive transfer of T cell receptor-engineered T cells (TCR-T) is a promising strategy for immunotherapy against solid tumors. However, the potential of CD4+ T cells in mediating tumor regression has been neglected. Nasopharyngeal cancer is consistently associated with EBV. Here, to evaluate the therapeutic potential of CD4 TCR-T in nasopharyngeal cancer, we screened for CD4 TCRs recognizing EBV nuclear antigen 1 (EBNA1) presented by HLA-DP5. Using mass spectrometry, we identified EBNA1567-581, a peptide naturally processed and presented by HLA-DP5. We isolated TCR135, a CD4 TCR with high functional avidity, that can function in both CD4+ and CD8+ T cells and recognizes HLA-DP5-restricted EBNA1567-581. TCR135-transduced T cells functioned in two ways: directly killing HLA-DP5+EBNA1+ tumor cells after recognizing EBNA1 presented by tumor cells and indirectly killing HLA-DP5-negative tumor cells after recognizing EBNA1 presented by antigen-presenting cells. TCR135-transduced T cells preferentially infiltrated into the tumor microenvironment and significantly inhibited tumor growth in xenograft nasopharyngeal tumor models. Additionally, we found that 62% of nasopharyngeal cancer patients showed 50%-100% expression of HLA-DP on tumor cells, indicating that nasopharyngeal cancer is well suited for CD4 TCR-T therapy. These findings suggest that TCR135 may provide a new strategy for EBV-related nasopharyngeal cancer immunotherapy in HLA-DP5+ patients.

Self-Adjuvanting Polyguanidine Nanovaccines for Cancer Immunotherapy.

Tapping into the innate immune system's power, nanovaccines can induce tumor-specific immune responses, which is a promising strategy in cancer immunotherapy. However, traditional vaccine design, requiring simultaneous loading of antigens and adjuvants, is complex and poses challenges for mass production. Here, we developed a tumor nanovaccine platform that integrates adjuvant functions into the delivery vehicle, using branched polyguanidine (PolyGu) nanovaccines. These nanovaccines were produced by modifying polyethylenimine (PEI) with various guanidine groups, transforming PEI's cytotoxicity into innate immune activation. The PolyGu nanovaccines based on poly(phenyl biguanidine ) (Poly-PBG) effectively stimulated dendritic cells, promoted their maturation via the TLR4 and NLRP3 pathways, and displayed robust in vivo immune activity. They significantly inhibited tumor growth and extended mouse survival. The PolyGu also showed promise for constructing more potent mRNA-based nanovaccines, offering a platform for personalized cancer vaccine. This work advances cancer immunotherapy toward potential clinical application by introducing a paradigm for developing self-adjuvanting nanovaccines.

Anti-OX40 Antibody Combined with HBc VLPs Delays Tumor Growth in a Mouse Colon Cancer Model

ObjectiveCombination immunotherapy strategies targeting OX40, a co-stimulatory molecule that can enhance antitumor immunity by modulating the proliferation, differentiation, and effector function of tumor-infiltrating T cells, have attracted much attention for their excellent therapeutic effects. In this study, we aimed to evaluate the antitumor efficacy of combined anti-OX40 and hepatitis B core virus-like particles (HBc VLPs) therapy using a mouse colon cancer model. MethodsHumanized B-hOX40 mice were injected subcutaneously with MC38 colon tumor cells and treated with HBc VLPs+anti-hOX40 antibody. Tumor growth was monitored. Flow cytometric analysis was performed to evaluate the populations of T cell subsets in the tumors. ResultsThe combination of anti-OX40 with HBc VLPs resulted in a significant delay in tumor growth, suggesting that a potent antitumor immunity was induced by the combination therapy. Further studies revealed that HBc VLPs+anti-OX40 treatment induced a significant increase in effector T cells (Teffs) and a significant decrease in regulatory T cells (Tregs) in the tumor microenvironment (TME), which accounted for the synergistic antitumor effect of anti-OX40 in combination with HBc VLPs. ConclusionCombination therapy of anti-hOX40 and HBc VLPs provides synergistic antitumor activity in colon cancer-bearing mice, which may represent a potential design strategy for cancer immunotherapy.

Synergizing CXCL9 with BRD4‐PROTAC Using Nanochaperone Boosts Robust T Cell‐Dependent Antitumor Immune Responses for Cancer Immunotherapy

AbstractThe efficacy of cancer immunotherapy is greatly restricted by insufficient infiltration of cytotoxic T lymphocytes and immunosuppressive microenvironment in tumor tissue. Here a potent strategy to address the limitations by combination therapy of chemokine (CXCL9) with BRD4‐PROTAC (dBET6) using the unique mixed‐shell polymeric micelle (MSPM)‐based nanochaperone (nChap) delivery platform is reported. CXCL9 significantly enhances the intratumoral infiltration of CD8+ T cells while dBET6 induces tumor cell immunogenic cell death (ICD) and downregulates the interferon‐γ (IFNγ)‐triggered programmed death ligand 1 (PD‐L1) expression, synergizing to boost robust T cell‐dependent antitumor immunity responses to enhance cancer immunotherapy is demonstrated. Moreover, this nano‐CXCL9/dBET6 exhibits reduced systemic toxicity, prolonged half‐life, and enhanced tumor accumulation in comparison to free drugs. This study provides a promising strategy for efficient cancer immunotherapy.

PROTAC-mediated NR4A1 degradation as a novel strategy for cancer immunotherapy.

An effective cancer therapy requires killing cancer cells and targeting the tumor microenvironment (TME). Searching for molecules critical for multiple cell types in the TME, we identified NR4A1 as one such molecule that can maintain the immune suppressive TME. Here, we establish NR4A1 as a valid target for cancer immunotherapy and describe a first-of-its-kind proteolysis-targeting chimera (PROTAC, named NR-V04) against NR4A1. NR-V04 degrades NR4A1 within hours in vitro and exhibits long-lasting NR4A1 degradation in tumors with an excellent safety profile. NR-V04 inhibits and frequently eradicates established tumors. At the mechanistic level, NR-V04 induces the tumor-infiltrating (TI) B cells and effector memory CD8+ T (Tem) cells and reduces monocytic myeloid-derived suppressor cells (m-MDSC), all of which are known to be clinically relevant immune cell populations in human melanomas. Overall, NR-V04-mediated NR4A1 degradation holds promise for enhancing anticancer immune responses and offers a new avenue for treating various types of cancers such as melanoma.

B10 cells: Development, phenotype, and function in cancer.

B10 cells, a specialized subset of regulatory B cells, have been identified in both mice and humans. These cells are characterized by their regulatory impact on immune dynamics, principally through their secretion of interleukin-10 (IL-10), a cytokine known for its anti-inflammatory properties. The pivotal role of immune mediators such as B10 cells is to maintain a delicate equilibrium between antitumor immunity and tumor-promoting responses. Emerging studies have cast B10 cells as key suppressors in the antitumor immune arsenal. They operate in synergy with a spectrum of immune cells within the innate and adaptive spectrums, contributing to a milieu that favors tumor progression and metastatic spread. In this comprehensive review, we will discuss the ontogeny, phenotype and effector functions of B10 cells in murine systems. We will also review the role of B10 cells in oncological models in animal studies and extend these findings to the human clinical context, elucidating their role in facilitating tumor immune evasion. A thorough understanding of these processes is imperative for the strategic targeting and attenuation of B10 cell activity, which is anticipated to be a cornerstone in the advancement of effective cancer immunotherapy strategies.

Targeting ALK averts ribonuclease 1-induced immunosuppression and enhances antitumor immunity in hepatocellular carcinoma

Tumor-secreted factors contribute to the development of a microenvironment that facilitates the escape of cancer cells from immunotherapy. In this study, we conduct a retrospective comparison of the proteins secreted by hepatocellular carcinoma (HCC) cells in responders and non-responders among a cohort of ten patients who received Nivolumab (anti-PD-1 antibody). Our findings indicate that non-responders have a high abundance of secreted RNase1, which is associated with a poor prognosis in various cancer types. Furthermore, mice implanted with HCC cells that overexpress RNase1 exhibit immunosuppressive tumor microenvironments and diminished response to anti-PD-1 therapy. RNase1 induces the polarization of macrophages towards a tumor growth-promoting phenotype through activation of the anaplastic lymphoma kinase (ALK) signaling pathway. Targeting the RNase1/ALK axis reprograms the macrophage polarization, with increased CD8+ T- and Th1- cell recruitment. Moreover, simultaneous targeting of the checkpoint protein PD-1 unleashes cytotoxic CD8+ T-cell responses. Treatment utilizing both an ALK inhibitor and an anti-PD-1 antibody exhibits enhanced tumor regression and facilitates long-term immunity. Our study elucidates the role of RNase1 in mediating tumor resistance to immunotherapy and reveals an RNase1-mediated immunosuppressive tumor microenvironment, highlighting the potential of targeting RNase1 as a promising strategy for cancer immunotherapy in HCC.

CXCR2 inhibition in G-MDSCs enhances CD47 blockade for melanoma tumor cell clearance

The use of colony-stimulating factor-1 receptor (CSF1R) inhibitors has been widely explored as a strategy for cancer immunotherapy due to their robust depletion of tumor-associated macrophages (TAMs). While CSF1R blockade effectively eliminates TAMs from the solid tumor microenvironment, its clinical efficacy is limited. Here, we use an inducible CSF1R knockout model to investigate the persistence of tumor progression in the absence of TAMs. We find increased frequencies of granulocytic myeloid-derived suppressor cells (G-MDSCs) in the bone marrow, throughout circulation, and in the tumor following CSF1R deletion and loss of TAMs. We find that G-MDSCs are capable of suppressing macrophage phagocytosis, and the elimination of G-MDSCs through CXCR2 inhibition increases macrophage capacity for tumor cell clearance. Further, we find that combination therapy of CXCR2 inhibition and CD47 blockade synergize to elicit a significant anti-tumor response. These findings reveal G-MDSCs as key drivers of tumor immunosuppression and demonstrate their inhibition as a potent strategy to increase macrophage phagocytosis and enhance the anti-tumor efficacy of CD47 blockade in B16-F10 melanoma.

C/EBPα mediates the maturation and antitumor functions of macrophages in human hepatocellular carcinoma

Recent studies have suggested that therapeutic upregulation of CCAAT/enhancer binding protein α (C/EBPα) prevents hepatocellular carcinoma (HCC) progression. However, the mechanisms underlying this outcome are not fully understood. In this study, we investigated the expression and functional roles of C/EBPα in human HCC, with a focus on monocytes/macrophages (Mφs). Paraffin-embedded tissues were used to visualize C/EBPα expression and analyze the prognostic value of C/EBPα+ monocytes/Mφs in HCC patients. The underlying regulatory mechanisms were examined using human monocyte-derived Mφs. The results showed that the expression of C/EBPα on monocytes/Mφs was significantly decreased in intra-tumor tissues compared to the corresponding peri-tumor tissues. C/EBPα+ monocytes/Mφs displayed well-differentiation and antitumor capacities, and the accumulation of these cells in tissue was associated with antitumor immune responses and predicted longer overall survival (OS) of HCC patients. Mechanistic studies demonstrated that C/EBPα was required for Mφ maturation and HLA-DR, CD169 and CD86 expression, which initiates antitumor cytotoxic T-cell responses; however, these effects were inhibited by monocyte autocrine IL-6- and IL-1β-induced suppression of mTOR1 signaling. Reprogramming Mφs via the upregulation of C/EBPα may provide a novel strategy for cancer immunotherapy in patients with HCC.

Exploratory analysis of biomarkers of response to durvalumab in advanced HER2-negative oesophago-gastric adenocarcinoma within a phase 2 clinical trial.

384 Background: Advanced oesophago-gastric cancers have showcased varied responses to immunotherapy based on biomarkers such as tumour mutational burden, microsatellite instability, and PD-L1 expression. However, these markers may not fully capture tumour heterogeneity and evolutionary dynamics. Hence, understanding the intricate relationship between immune selection, specifically immune dN/dS,1 and tumour evolution is vital for devising personalized therapeutic strategies. Methods: In our phase 2 open label, multicentre, randomised PLATFORM trial (NCT02678182), patients received maintenance durvalumab post first-line chemotherapy. A survival advantage was not seen with maintenance durvalumab compared to surveillance and exploratory analysis of PD-L1 expression was not associated with improved survival outcomes.2 However, a subset of patients treated with durvalumab experienced durable responses and some experienced incremental radiological responses. A pilot substudy on a selected cohort (n=24) of these patients was designed to explore the potential of immunogenomics evolutionary-based metrics, notably dN/dS, as predictive biomarkers. DNA and RNA from FFPE baseline tumour samples underwent analysis, examining genomic factors including tumour mutational burden, indel signatures, PDL1 status, and immune evasion mechanisms. Furthermore, the evolutionary metric, immune dN/dS, which has implications in tumour immunoediting and its response to immunotherapies, was scrutinized. Results: A dominant indel mutational signature emerged from the analysis. The majority of patients displayed a significantly higher number of indel variants, compared to non-synonymous and synonymous single-nucleotide variants. A recurring observation was dN/dS values consistently above 1, indicating positive selection for non-synonymous somatic variants. Additionally, hypermutation in driver genes, notably TP53 and XIRP2, was detected. One patient, with a unique dN/dS < 1, showcased survival beyond four years without liver metastases. Immune dN/dS > 1 and no evidence of liver metastases displayed the best prognosis after treatment in contrast with those that have immune dN/dS < 1 with or without liver metastases. Conclusions: Immune dN/dS emerges as a promising tool to decode tumour evolutionary mechanisms, providing profound insights into the dynamics of tumour evolution in advanced HER2 negative oesophago-gastric cancer patients receiving durvalumab immunotherapy. This pilot study underscores the potential of this novel immunogenomic approach in improving patient stratification and tailoring therapeutic strategies in cancer immunotherapy. 1. Zapata et al, Nature Genetics, 2023. 2. Fong et al, J Clin Oncol, 2021. Clinical trial information: NCT02678182 .