InVivoPlus anti-mouse PD-1 (CD279)

Therapies that harness the immune system to target and eliminate tumour cells have revolutionized cancer care. Immune checkpoint blockade (ICB), which boosts the anti-tumour immune response by inhibiting negative regulators of T cell activation1-3, is remarkably successful in a subset of cancer patients. Yet a significant proportion do not respond to treatment, emphasizing the need to understand factors influencing the therapeutic efficacy of ICB4-9. The gut microbiota, consisting of trillions of microorganisms residing in the gastrointestinal tract, has emerged as a critical determinant of immune function and response to cancer immunotherapy, with several studies demonstrating association of microbiota composition with clinical response10-16. However, a mechanistic understanding of how gut commensal bacteria influence the efficacy of ICB remains elusive. Here we use a gut commensal microorganism, segmented filamentous bacteria (SFB), which induces an antigen-specific T helper 17 (TH17) cell effector program in the small intestine lamina propria (SILP)17, to investigate how colonization with this microbe affects the efficacy of ICB in restraining distal growth of tumours sharing antigen with SFB. We find that anti-programmed cell death protein 1 (PD-1) treatment effectively inhibits the growth of implanted SFB antigen-expressing melanoma only if mice are colonized with SFB. Through T cell receptor (TCR) clonal lineage tracing, fate mapping and peptide-major histocompatability complex (MHC) tetramer staining, we identify tumour-associated SFB-specific T helper 1 (TH1)-like cells derived from the homeostatic TH17 cells induced by SFB colonization in the SILP. These gut-educated ex-TH17 cells produce high levels of the pro-inflammatory cytokines interferon (IFN)-γ and tumour necrosis factor (TNF) within the tumour microenvironment (TME), enhancing antigen presentation and promoting recruitment, expansion and effector functions of CD8+ tumour-infiltrating cytotoxic lymphocytes and thereby enabling anti-PD-1-mediated tumour control. Conditional ablation of SFB-induced IL-17A+CD4+ T cells, precursors of tumour-associated TH1-like cells, abolishes anti-PD-1-mediated tumour control and markedly impairs tumour-specific CD8+ T cell recruitment and effector function within the TME. Our data, as a proof of principle, define a cellular pathway by which a single, defined intestinal commensal imprints T cell plasticity that potentiates PD-1 blockade, and indicate targeted modulation of the microbiota as a strategy to broaden ICB efficacy.

Type 1 conventional dendritic cells (cDC1s) are unique in their efferocytosis1 and cross-presenting abilities2, resulting in antigen-specific T cell immunity3 or tolerance4-8. However, the mechanisms that underlie cDC1 tolerogenic function remain largely unknown. Here we show that the erythropoietin receptor (EPOR) acts as a critical switch that determines the tolerogenic function of cDC1s and the threshold of antigen-specific T cell responses. In total lymphoid irradiation-induced allograft tolerance9,10, cDC1s upregulate EPOR expression, and conditional knockout of EPOR in cDC1s diminishes antigen-specific induction and expansion of FOXP3+ regulatory T (Treg) cells, resulting in allograft rejection. Mechanistically, EPOR promotes efferocytosis-induced tolerogenic maturation7,11 of splenic cDC1s towards late-stage CCR7+ cDC1s characterized by increased expression of the integrin β8 gene12 (Itgb8), and conditional knockout of Itgb8 in cDC1s impairs tolerance induced by total lymphoid irradiation plus anti-thymocyte serum. Migratory cDC1s in peripheral lymph nodes preferentially express EPOR, and their FOXP3+ Treg cell-inducing capacity is enhanced by erythropoietin. Reciprocally, loss of EPOR enables immunogenic maturation of peripheral lymph node migratory and splenic CCR7+ cDC1s by upregulating genes involved in MHC class II- and class I-mediated antigen presentation, cross-presentation and costimulation. EPOR deficiency in cDC1s reduces tumour growth by enhancing anti-tumour T cell immunity, particularly increasing the generation of precursor exhausted tumour antigen-specific CD8+ T cells13 in tumour-draining lymph nodes and supporting their maintenance within tumours, while concurrently reducing intratumoural Treg cells. Targeting EPOR on cDC1s to induce or inhibit T cell immune tolerance could have potential for treating a variety of diseases.

Triple-negative breast cancer (TNBC) remains a lethal malignancy with limited targeted therapies and high metastatic rates. Cancer cells evade macrophage clearance by overexpressing anti-phagocytic cell surface proteins, termed "don't eat me" signals. Blocking antibodies (e.g., anti-CD47) against these signals show therapeutic promise in multiple cancers, yet variable responses and limited durability of efficacy to such agents imply additional unknown "don't eat me" signals exist. Here, we detected positive CD52 expression in tumors from TNBC patients and demonstrated that CD52 on TNBC cells facilitates immune evasion by engaging the inhibitory receptor sialic acid-binding Ig-like lectin G (Siglec-G) on tumor-associated macrophages. Genetic ablation of either CD52 or Siglec-G, as well as antibody-mediated blockade of their interaction restored macrophage phagocytic activity both in vitro and in vivo. This consequently suppressed tumor progression, improved survival, and promoted an immunologically active tumor microenvironment in TNBC mouse models. Additionally, cotreatment with anti-CD52 sensitized tumor cells to PD-1 blockade therapy in the spontaneous MMTV-PyMT TNBC model. Our findings identify CD52 as a prominently expressed anti-phagocytic checkpoint in TNBC and reveal the therapeutic potential of dual PD-1/CD52 blockade as a novel immunotherapeutic strategy.

Cancer immunotherapy is only effective in a subset of patients, highlighting the need for effective biomarkers and combination therapies. Here, we systematically identify genetic determinants of cancer cell sensitivity to anti-tumor immunity by performing whole-genome CRISPR-Cas9 knockout screens in autologous tumoroid-T cell co-cultures, isogenic cancer cell models deficient in interferon signaling, and in the context of four cytokines. We discover that loss of CHD1 and MAP3K7 (encoding TAK1) potentiates the transcriptional response to IFN-γ, thereby creating an acquired vulnerability by sensitizing cancer cells to tumor-reactive T cells. Immune checkpoint blockade is more effective in a syngeneic mouse model of melanoma deficient in Chd1 and Map3k7 and is associated with elevated intra-tumoral CD8+ T cell numbers and activation. CHD1 and MAP3K7 are recurrently mutated in cancer, and reduced expression in tumors correlates with response to immune checkpoint inhibitors in patients, nominating these genes as potential biomarkers of immunotherapy response.

Immunotherapy has improved outcomes in many cancers, yet the clinical benefits remain limited in prostate cancer. We evaluated whether an adenovirus-based bivalent prostate cancer vaccine (Ad-PS2) targeting two tumor antigens could be strengthened by combination with immune checkpoint blockade. Using immunocompetent mouse models, we found that Ad-PS2 combined with low-dose anti-CTLA4 generated robust anti-tumor immunity capable of eliminating established tumors, exceeding the effects of either treatment alone. Tumor-free mice resisted subsequent tumor rechallenge, indicating durable immune protection. Tumor analysis revealed a significant increase in intratumor CD8+ T cell infiltration with Ad-PS2 and anti-CTLA4, whereas anti-PD1 alone produced minimal infiltration and, with the vaccine, provided no therapeutic advantage. These results highlight a mechanistically synergistic interaction between dual antigen-targeted vaccination and CTLA4 blockade and illustrate how rational combination immunotherapy can overcome resistance in prostate cancer. This work defines a strategy that could inform future translational approaches for improving immunologic control of prostate cancer.

Background/Objectives: Non-melanoma skin cancer, which includes cutaneous squamous cell carcinoma (cSCC), ranks as the 5th most common cancer globally with high morbidity and more total deaths than melanoma despite having a lower mortality rate. While most cSCC cases can be treated with surgery, locally advanced, metastatic, and high-risk cSCC tumors are associated with a worse prognosis with higher rates of recurrence and require multimodality therapy. However, there is limited data on animal models of cutaneous squamous cell carcinoma for the use of combinatory immunotherapy and radiation. Methods: In this study, spontaneously generated tumors using DMBA/TPA were treated over three weeks with either IgG control, anti-PD1 antibody monotherapy, 8 Gy of localized radiation, or a combination of anti-PD1 and 8 Gy of radiation followed by anti-PD1 therapy. Results: We found that while anti-PD1 therapy showed a trend toward slowed tumor growth compared to controls, this difference was not statistically significant (p = 0.0775), with most mice showing continued tumor progression. Preliminary histological analysis suggested that anti-PD1 treatment increased CD8+ T cell infiltration, and the addition of radiation further enhanced CD8+ responses but added greater variability. A pathologic review revealed that irradiated tumors were associated with fibroblastic spindle-like cell morphology. Conclusions: This animal model represents a potential preclinical model for studying CSCC with limited responses to immunotherapy to understand potential mechanisms of resistance.

T-cell engager (TCE)-based immunotherapy is clinically validated in hematological cancers. However, application in solid tumors faces hurdles including T cell penetration, the immunosuppressive tumor microenvironment, and toxicity. We develop an mRNA-encoded TCE (MTS105) targeting Glypican-3, the hepatocellular carcinoma antigen, delivered via lipid nanoparticles directly to liver tissue. In mice, rats, and cynomolgus monkeys, MTS105 exhibits higher liver exposure versus plasma. Liver-orthotopic tumor-bearing mice achieve complete, dose-dependent regression, with fast intratumoral T cell activation owing to sustained higher liver and tumor functional TCE exposure versus conventional antibody-based TCE. In vivo, MTS105 induces intratumoral CD8 cell precursor and terminally differentiated memory subsets with high activation scores. In cynomolgus monkeys, MTS105 displays favorable, linear plasma pharmacokinetics including mRNA, ionizable lipid, and translated TCE following single and repeated-four-weekly dosing (up to 45 μg/kg). No severe adverse effects or gross pathology were observed. Our results thus support the advancement of MTS105 into clinical trials, with a first-in-human study currently underway.

Small cell lung cancer (SCLC) is characterized by its highly aggressive phenotype and dismal outcome. Despite the benefit of adding immune checkpoint blockade to standard chemotherapy, tumors acquire the ability to evade immunosurveillance and develop resistance. To investigate these underlying mechanisms, we perform high-dimensional profiling of human and murine SCLC specimens. In matched primary and metastatic human samples, we observe MHC-I loss in metastases, highlighting its role in immune evasion. Correspondingly, silencing MHC-I in SCLC cells drastically reduces immune infiltration and promotes metastasis in mice. Using mass spectrometry and phospho-tyrosine kinase analyses, we identify ERBB2 signaling as a suppressor of MHC-I and driver of immune-modulatory transcripts. Mechanistically, genetic and pharmacologic blockade of ERBB2 induces MHC-I in a STING-dependent manner and prevents immune evasion in autochthonous murine SCLC. Strikingly, combining ERBB2 inhibition with anti-PD-1 elicits profound synergistic responses in preclinical models, suggesting this combination for future clinical trials in SCLC patients.

We present the preclinical rationale and clinical data from a phase 1b trial investigating the STING agonist dazostinag plus pembrolizumab following hypofractionated radiotherapy (RT) in patients with advanced non-small cell lung cancer (NSCLC), triple-negative breast cancer (TNBC), or squamous cell carcinoma of the head and neck (SCCHN) whose disease had progressed on prior checkpoint inhibitors (CPI; NCT04879849).

Immunotherapy resistance in microsatellite-stable colorectal cancer (CRC) remains a major therapeutic challenge. Recent strategies to overcome the immunosuppressive tumor microenvironment have focused on reactivating innate immune pathways, particularly the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) axis, which links cytosolic DNA sensing to proinflammatory cytokine production and T cell activation. Although STING agonists show promise, their clinical application is limited by poor drug stability and cytokine storms triggered by excessive STING activation. This study establishes valosin-containing protein (VCP/p97) as a druggable target to potentiate cGAS-STING-driven antitumor immunity, offering a promising therapeutic strategy to overcome immunotherapy resistance in CRC.

Recent clinical studies highlight the effectiveness of combining cytotoxic agents with immunotherapies, emphasizing the need for next-generation treatments that integrate both therapeutic approaches. Here, we use 30 cancer cell lines, 15 tumor models, and 45 patient samples to develop N17350, a therapeutic elastase that targets the "neutrophil elastase pathway" to induce tumor regression and stimulate anti-tumor immunity. N17350 leverages linker histone H1.0 and H1.2, proteins elevated in many cancers, to trigger immunogenic cancer cell death while preserving immune cells. Intra-tumoral N17350 administration induces rapid, genotype-independent tumor regression, triggering CD8+ T cell activation to promote durable responses and enable checkpoint inhibitor efficacy in refractory models. N17350 maintains potency with repeated dosing and across diverse treatment histories, including resistance to chemotherapies and checkpoint inhibitors. These findings support the advancement of N17350 to first-in-human clinical trials as a cytotoxic agent designed to stimulate anti-tumor immunity by selectively killing cancer cells.

Immune checkpoint blockade (ICB) therapy, which has revolutionized cancer treatment, has been approved for the treatment of triple-negative breast cancer (TNBC). Unfortunately, most patients with TNBC are either not eligible for treatment or exhibit resistance, resulting in limited overall survival benefits. There is an urgent need to elucidate the mechanisms of resistance and enhance therapeutic efficacy. Here, via CRISPR activation (CRISPRa) screening, we identified family with sequence similarity 114 member A1 (FAM114A1) as a key mediator of immune evasion and ICB resistance in TNBC. Mechanistically, FAM114A1 binds p85α to disrupt the p85α/p110α protein complex, thus activating the PI3K/AKT pathway and simultaneously preventing condensate formation of E2F Transcription Factor 4 (E2F4) to promote E2F4-driven Metadherin (MTDH) transcription. Upregulation of these FAM114A1-mediated pathways suppresses tumor antigen presentation and consequently attenuates antitumor immunity in TNBC. Moreover, targeting FAM114A1 improves the therapeutic effectiveness of anti-PD-1 therapy in mouse models, and a FAM114A1-based signature shows strong predictive performance for identifying patients with TNBC who may benefit from ICB. Collectively, our findings not only reveal that FAM114A1 is an immune evasion driver but also highlight it as a promising biomarker and therapeutic target. Our study provides new insights into TNBC immune evasion and outlines a potential avenue to improve the effectiveness of ICB.

Immune checkpoint inhibitor (ICIs)-associated cardiotoxicity is a significant cause of immune-related adverse events and mortality in cancer immunotherapy, lacking effective preventative or therapeutic strategies. Xihuang Pill (XHW), a traditional Chinese medicine with established anti-inflammatory properties and clinical use in cancer treatment and adverse event mitigation, merits investigation for its efficacy against ICIs-induced cardiac toxicity.

Background. The dense hyaluronan (HA)-rich stroma in solid tumors can prevent effective tumor growth inhibition by hindering drug delivery and immune cell infiltration. However, the degradation of HA alone by systemic delivery of hyaluronidase has not shown significant improvement of tumor growth inhibition. Objectives/Methods. In this study, we targeted hyaluronan degradation by using antibody-enzyme (AbEn) molecules by fusing antibodies to a recombinant human hyaluronidase (HYAL). Results. The AbEn molecules were stable, retained both antigen-binding and enzymatic activities, and demonstrated a prolonged serum half-life of 132 h in rodent models. In the HA-rich colorectal cancer model, the cancer-associated fibroblast (CAF)-directed AbEn, TAVO423 (FAP × LRRC15 × HYAL trispecific antibody) achieved greater intratumoral HA depletion resulting in superior tumor growth inhibition compared to untargeted HYAL. Furthermore, the combination of TAVO423 in combination with other solid tumor cell targeting modalities such as 5-fluorouracil (5-FU), anti-PD-L1 monoclonal antibody, a PD-L1 × CD3 bispecific T-cell engager (TCE), and a CD318-targeting antibody-drug conjugate (ADC) all demonstrated enhanced tumor growth inhibition (TGI) values of 49-67% as compared to the respective monotherapy TGI values of 1-28%. In addition, TAVO423 improved the antitumor response of a 5T4 × CD3 TCE with an increase in TGI from 73% to 92% in an in vivo HA-rich pancreatic cancer model. The CAF-targeted HA degradation mediated by TAVO423 also reversed immune exclusion by increasing the density of CD8+ tumor-infiltrating lymphocytes (TILs) by 6-9-fold and synergized with PD-1 blockade to enhance TGI from 33% to 51% in an in vivo immunocompetent EMT-6 breast cancer model. Conclusions. These findings demonstrated the broad potential of the modular AbEn platform for targeted HA degradation to overcome barrier entry in stromal HA-rich solid tumors.

Immune checkpoint inhibitors (ICIs), particularly programmed cell death protein 1 (PD-1) blockades, have redefined oncology in the last decade. Previous studies on PD-1 blockades mostly concentrate on their interactions with immune cells. This study aims to investigate how PD-1 blockades affect endothelial cell (EC) heterogeneity in the tumor microenvironment (TME) and to explore potential targets for enhancing the anti-tumor effects of PD-1 blockades. Here, we established a pan-cancer EC atlas from the public database and revealed that PD-1 blockades repress the angiogenic population in ECs and inhibit the CXCL12-CXCR4 signaling derived from ECs. Using a murine tumor model built with Lewis Lung Carcinoma cell line, we further validated our findings that a PD-1 blockade, as well as a CXCR4 antagonist AMD3100, inhibited EC population in tumors and their CXCL12 expression. In addition, the combo therapy of the PD-1 blockade and AMD3100 showed superior anti-tumor effects to monotherapy. Moreover, we predicted MYC to be the potential regulator through which PD-1 blockades affect ECs. Together, our results suggest that PD-1 blockades have an anti-angiogenic effect besides boosting T cell immunity, and the CXCL12/CXCR4 pathway is a potential target for enhancing the effectiveness of PD-1 blockades.

Perineural invasion (PNI) is a well-established factor of poor prognosis in multiple cancer types1, yet its mechanism remains unclear. Here we provide clinical and mechanistic insights into the role of PNI and cancer-induced nerve injury (CINI) in resistance to anti-PD-1 therapy. Our study demonstrates that PNI and CINI of tumour-associated nerves are associated with poor response to anti-PD-1 therapy among patients with cutaneous squamous cell carcinoma, melanoma and gastric cancer. Electron microscopy and electrical conduction analyses reveal that cancer cells degrade the nerve fibre myelin sheets. The injured neurons respond by autonomously initiating IL-6- and type I interferon-mediated inflammation to promote nerve healing and regeneration. As the tumour grows, the CINI burden increases, and its associated inflammation becomes chronic and skews the general immune tone within the tumour microenvironment into a suppressive and exhaustive state. The CINI-driven anti-PD-1 resistance can be reversed by targeting multiple steps in the CINI signalling process: denervating the tumour, conditional knockout of the transcription factor mediating the injury signal within neurons (Atf3), knockout of interferon-α receptor signalling (Ifnar1-/-) or by combining anti-PD-1 and anti-IL-6-receptor blockade. Our findings demonstrate the direct immunoregulatory roles of CINI and its therapeutic potential.

As a part of the commensal microbiome, the regulatory role of the intratumoral microbiome in tumor immunity is gradually revealed. However, the relationship between the intratumoral microbiome and the efficacy of immune checkpoint inhibitors (ICIs) clinical treatment remains unclear. Here, we collect RNA sequencing (RNA-seq) data and clinical information from publicly available ICIs therapy cohorts. By developing an improved bioinformatics pipeline to identify the intratumoral microbiome and performing a comprehensive association analysis, we find that the intratumoral microbiome is associated with response to ICIs and characteristics of the tumor microenvironment (TME). In vivo experiments demonstrate that intratumoral injection of Burkholderia cepacia, Priestia megaterium, or Corynebacterium kroppenstedtii, which were selected from our analysis results, would synergize with anti-PD-1 therapy to inhibit tumor growth and enhance antitumor immunity. Our findings highlight the essential role of the intratumoral microbiome in the clinical effectiveness differences of ICIs, suggesting its potential in future ICIs combination therapy.

Radiotherapy (RT)-elicited antitumor immunity serves as a pivotal mechanism in RT-mediated tumor control. The strategic integration of RT with immunotherapies, particularly immune checkpoint blockade (ICB), is revolutionizing cancer therapeutics, demonstrating remarkable clinical potential. In this context, identifying molecular targets to potentiate radioimmunotherapy (RIT) efficacy represents a critical research priority. Emerging as a central immunomodulatory axis, the cGAS/STING signaling pathway bridges DNA damage response with antitumor immunity, positioning itself as a prime therapeutic target for radiation sensitization. Our study unveils caspase-activated DNase (CAD) as a previously unrecognized suppressor of cGAS/STING signaling that governs radiosensitivity in colorectal cancer (CRC). CAD physically blocks STING dimerization and cGAMP binding through a nuclease-independent function, thereby compromising RT-induced STING activation and subsequent type I interferon (IFN-I) production. Functional analyses demonstrated that CAD ablation potentiates CD8+ T cell infiltration/activation within the tumor microenvironment and synergizes with anti-PD-1 immunotherapy upon radiation. Translational validation revealed clinical correlations between CAD overexpression in CRC specimens and suboptimal radiotherapy responses coupled with diminished intratumoral CD8+ T cell infiltration. Collectively, our findings establish CAD as a novel rheostat of cGAS-STING signaling and propose CAD inhibition as a promising combinatorial strategy to enhance RT and RIT efficacy in CRC.

Cancer genomic studies have identified frequent alterations in genes encoding components of the SWI/SNF chromatin remodeling complex, including SMARCA4 and ARID1A. Importantly, clinical reports indicate that SMARCA4-mutant lung cancers respond poorly to immunotherapy and have dismal prognosis. In this study, we corroborated the clinical findings by using immune-humanized, syngeneic, and genetically engineered mouse models of lung cancer harboring SMARCA4 deficiency. Specifically, models with SMARCA4 loss showed decreased response to anti-PD-1 immunotherapy associated with significantly reduced infiltration of dendritic cells and CD4+ T cells into the tumor microenvironment. SMARCA4 loss in tumor cells led to profound downregulation of STING1, IL1β, and other components of the innate immune system, as well as inflammatory cytokines that are required for efficient recruitment and activity of immune cells. The deregulation of gene expression was caused by cancer cell-intrinsic reprogramming of the enhancer landscape with marked loss of chromatin accessibility at enhancers of genes involved in innate immune response, such as STING1, IL1β, type I IFN, and inflammatory cytokines. Interestingly, the transcription factor NF-κB-binding motif was enriched in enhancers that lose accessibility upon SMARCA4 deficiency. Furthermore, SMARCA4 and NF-κB co-occupied the same genomic loci on enhancers associated with STING1 and IFNβ, indicating a functional interplay between SMARCA4 and NF-κB. Taken together, these findings provide the mechanistic basis for the poor response of SMARCA4-mutant tumors to immunotherapy and establish a functional link between SMARCA4 and NF-κB in innate immune and inflammatory gene expression regulation. Significance: Epigenetic reprogramming in SMARCA4-mutant cancer cells alters immune infiltration and limits immunotherapy efficacy by downregulating immunostimulatory gene expression, which could potentially be targeted to overcome immunotherapy resistance in SMARCA4-deficient tumors.

Strategies for deploying indoleamine 2,3-dioxygenase 1 (IDO1)-targeted therapies for use against cancer have focused on IDO1's role in promoting peripheral immune tolerance that shields tumors from effector T cells. However, preclinical investigation of both primary and metastatic tumor development in the lungs has uncovered a previously unappreciated role for IDO1 in directing a counterregulatory response to interferon (IFN)-γ that realigns the local inflammatory environment to promote tumor neovascularization. Understanding how to therapeutically leverage the ability of IDO1 inhibitors to subvert inflammatory neovascularization within the tumor microenvironment has potential ramifications for future clinical development of these compounds.