InVivoMAb anti-mouse CD8α

Despite progress in immunotherapy for several solid tumors, pancreatic ductal adenocarcinoma (PDAC) remains largely unresponsive, primarily due to its profoundly immunosuppressive tumor microenvironment (TME) characterized by limited CD8+ T cell infiltration. Novel strategies are needed to overcome this immune resistance and enhance the efficacy of checkpoint blockade.

Beyond supporting cancer cell proliferation, tumor growth relies on the ability of cancer cells to evade immune surveillance. Identifying novel molecules that promote tumor immune escape may help develop more effective immunotherapeutic strategies. The histone acetyltransferase E1A-binding protein p300 (EP300) is a key epigenetic regulator that modulates gene transcription through chromatin remodeling and acetylation of histones and transcription factors. However, its role in regulating immune evasion remains incompletely understood. This study investigates the impact of EP300 on tumor immune escape and suggests its potential as an immunotherapeutic target.

Although Kirsten rat sarcoma virus (KRAS) G12C inhibitors alter the treatment strategy for patients with KRAS G12C-mutant lung cancer, their efficacy remains insufficient to eliminate tumors. Here, we identify that inhibition of mutant KRAS promotes escape from macrophage phagocytosis by upregulating the expression of cluster of differentiation 47 (CD47) and CD24. These proteins are induced by the binding of FOXA1 to the super-enhancer of CD47 and grainyhead-like transcription factor 2 (GRHL2) to the promoter of CD24, respectively. Whereas the addition of an anti-CD47 antibody restores macrophage phagocytosis, phagocytic macrophages induce programmed death-ligand 1 (PD-L1) expression, resulting in the suppression of CD8 T cell activation. Combination of a KRAS inhibitor with anti-CD47 and anti-PD-L1 antibodies achieves long-term survival in an orthotopic murine model recalcitrant to KRAS inhibition with immune checkpoint therapy. These results suggest that targeting KRAS with an anti-CD47 antibody and immune checkpoint blockade is a promising strategy, especially in immune-cold lung tumors.

Transplantation is the definitive treatment for patients with end-stage organ failure. Following allogeneic transplant, the recipient's immune system recognizes transplanted cells or organs as foreign. The immune system recognizes and targets the foreign tissue for damage through cell-mediated rejection (CMR) and/or antibody-mediated rejection (AMR). Immunosuppressive agents are utilized to protect the transplant from rejection and extend transplant function and survival. Despite advances in immunosuppressive agents, AMR remains a critical barrier to the success of transplantation. AMR occurs when B cells produce alloantibodies that bind the allograft causing antibody-dependent, complement-mediated or immune cell-mediated cytotoxic damage. Continued research on AMR is required to develop novel and effective therapeutic strategies. Murine AMR models have been utilized to investigate mechanisms mediating the production of posttransplant alloantibodies and the pathology of damage to the transplanted allograft. These models facilitating the investigation of cellular and molecular mechanisms of alloantibody production and allograft damage are critical to the development of novel therapeutic strategies to prevent and treat AMR. This article describes the methodologies used to study AMR in animal transplant models. These include protocols to detect and measure alloantibodies, allograft survival, AMR pathology, and effector immune cell responses following transplantation. © 2025 The Author(s). Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Alloserum transfer into immune-incompetent recipient mice to determine transplant organ susceptibility to AMR Basic Protocol 2: Allogeneic transplantation into immune-deficient mice to study critical cellular and molecular pathways impacting AMR Support Protocol 1: Quantification of posttransplant alloantibody titer Support Protocol 2: Monitoring of transplant allograft survival Support Protocol 3: Assessment of immunopathology and severity of AMR Basic Protocol 3: Analysis of posttransplant immunologic responses.

Wild-type interleukin (IL)-2 induces anti-tumor immunity and toxicity, predominated by vascular leak syndrome (VLS) leading to edema, hypotension, organ toxicity, and regulatory T cell (Treg) expansion. Efforts to uncouple IL-2 toxicity from its potency have failed in the clinic. We hypothesize that IL-2 toxicity is driven by cytokine release syndrome (CRS) followed by VLS and that coupling IL-2 with IL-10 will ameliorate toxicity. Our data, generated using human primary cells, mouse models, and non-human primates, suggest that coupling of these cytokines prevents toxicity while retaining cytotoxic T cell activation and limiting Treg expansion. In syngeneic murine tumor models, DK210 epidermal growth factor receptor (EGFR), an IL-2/IL-10 fusion molecule targeted to EGFR via an anti-EGFR single-chain variable fragment (scFV), potently activates T cells and natural killer (NK) cells and elicits interferon (IFN)γ-dependent anti-tumor function without peripheral inflammatory toxicity or Treg accumulation. Therefore, combining IL-2 with IL-10 uncouples toxicity from immune activation, leading to a balanced and pleiotropic anti-tumor immune response.

Effective small molecule therapies are a major unmet need in triple-negative breast cancer. Therefore, we examined the mechanism of action of a novel cancer therapeutic target in preclinical mouse models focusing on the α7 nicotinic acetylcholine receptor (CHRNA7). E0771 breast tumor cells were implanted into CHRNA7KO mice to determine the role of CHRNA7, which is expressed in tumor-associated myeloid immune cells. We observed that tumor-bearing CHRNA7KO mice had decreased survival and increased tumor burden linked to a CHRNA7-mediated reduction in immune cell activation. Based on the tumor permissive phenotype of CHRNA7KO mice, we tested the effect of a small molecule agonist of CHRNA7, AR-R17779, in several mouse models of breast cancer. For example, in both the E0771 tumor model and PyMT tumor models, treatment with AR-R17779 increased survival. In the 4T1 breast tumor model, treatment with AR-R17779 also increased survival, with a well-defined reduction in primary tumor burden and lung metastases. The antitumorigenic effects of AR-R17779 were linked to an adaptive immune response based on in vivo studies showing a survival benefit when AR-R17779 was administered as a combination therapy with anti-PD-L1, demonstrating that the effects of AR-R17779 were dependent on CD8 T cells, and in vitro studies showing AR-R17779 treatment of dendritic cells increased T cell activation. Together these findings supported the importance of CHRNA7 as a novel therapeutic target expressed on dendritic cells based on its role in potentiating the adaptive immune response in mouse models of breast cancer.

Optimizing intratumoral dendritic cell (DC)-T cell responses is pivotal for effective cancer immunotherapy. However, the mechanistic governing these dynamics within the tumor microenvironment (TME) remains unclear, and strategies to improve their therapeutic potential are underexplored. Here, we show that precise radiotherapy activates the pro-TLR7/8 agonist imidazoquinoline (IMDQ) locally in preclinical tumor models, stimulating DCs to elicit T cell immunity without the need for further recruitment or causing systemic toxicity. Mechanistically, this synergistic approach triggers type I interferon via STING and MyD88 signaling pathways, strengthening local immune responses. Importantly, we reveal that fractionated, low-dose radiotherapy can effectively optimize local DC-T cell dynamics to control the irradiated tumor, while also promoting abscopal effect. Thus, our findings underscore the critical role of harnessing intratumoral DCs to reinvigorate pre-existing T cell immunity and provide mechanistic insights into improving both local and distal tumor control, opening new avenues for advancing cancer immunotherapy.

Resistance to v-raf murine sarcoma viral oncogene homolog B1 (BRAF) plus mitogen-activated protein kinase kinase (MEK) inhibition (BRAFi+MEKi) in BRAFV600E-mutant gliomas drives rebound, progression, and high mortality, yet it remains poorly understood. This study addresses the urgent need to develop treatments for BRAFi+MEKi-resistant glioma using preclinical mouse models and patient-derived materials. BRAFi+MEKi reveals glioma plasticity by heightening cell state transitions along glial differentiation trajectories, giving rise to astrocyte- and immunomodulatory oligodendrocyte (OL)-like states. PD-L1 upregulation in OL-like cells links cell state transitions to immune evasion, possibly orchestrated by Galectin-3. BRAFi+MEKi induces interferon response signatures, tumor infiltration, and suppression of T cells. Combining BRAFi+MEKi with immune checkpoint inhibition enhances survival in a T cell-dependent manner, reinvigorates T cells, and outperforms individual or sequential therapies in mice. Elevated PD-L1 expression in BRAF-mutant versus BRAF-wild-type glioblastoma supports the rationale for PD-1 inhibition in patients. These findings underscore the potential of targeting glioma plasticity and highlight combination strategies to overcome therapy resistance in BRAFV600E-mutant high-grade glioma.

Immunotherapies targeting the programmed cell death 1 (PD-1)/programmed death ligand 1 (PD-L1) have shown great promise for a subset of patients with non-small cell lung cancer (NSCLC). However, safe and robust combination therapies are still needed to bring the benefit to broader patient populations.

Posttranscriptional modifications are involved in cancer progression. However, the function and regulatory mechanism of mRNA acetylation modification remains largely unknown. Here, we discover an unexpected role of N4-acetylcytidine (ac4C) RNA acetyltransferase NAT10 in reshaping the tumor immune microenvironment. By analyzing patients' data, we find that NAT10 is upregulated in tumor tissues, and negatively correlated with immune cell infiltration and overall survival. Loss of tumoral NAT10 enhances tumor-specific cellular immune response and suppresses tumor growth. Mechanistically, MYC is identified as a key downstream target of NAT10 via enhancing mRNA ac4C modification. Inhibition of NAT10 blocks the MYC/CDK2/DNMT1 pathway, enhances double-stranded RNA (dsRNA) formation, which triggers type I interferon response and improves tumor specific CD8+ T cell response in vivo. More importantly, the inhibition of NAT10, using either small molecule inhibitor (Remodelin) or PEI/PC7A/siNAT10 nanoparticles, synergize PD-1 blockade in elevating anti-tumor immune response and repressing tumor progression. Our findings thus uncover the crucial role of tumor-intrinsic NAT10 in tumor immune microenvironment, which represents a promising target for enhancing cancer immunotherapy.

Despite recent progress in cancer treatment, liver metastases persist as an unmet clinical need. Here, we show that arming liver and tumor-associated macrophages in vivo to co-express tumor antigens (TAs), IFNα, and IL-12 unleashes robust anti-tumor immune responses, leading to the regression of liver metastases. Mechanistically, in vivo armed macrophages expand tumor reactive CD8+ T cells, which acquire features of progenitor exhausted T cells and kill cancer cells independently of CD4+ T cell help. IFNα and IL-12 produced by armed macrophages reprogram antigen presenting cells and rewire cellular interactions, rescuing tumor reactive T cell functions. In vivo armed macrophages trigger anti-tumor immunity in distinct liver metastasis mouse models of colorectal cancer and melanoma, expressing either surrogate tumor antigens, naturally occurring neoantigens or tumor-associated antigens. Altogether, our findings support the translational potential of in vivo armed liver macrophages to expand and rejuvenate tumor reactive T cells for the treatment of liver metastases.

Immune checkpoint blockade (ICB) therapy only induces durable responses in a subset of cancer patients. The underlying mechanisms of such selective efficacy remain largely unknown. By analyzing the expression profiles of immune checkpoint molecules in different statuses of murine tumors, we found that tumor progression generally randomly upregulated multiple immune checkpoints, thus increased the Heterogeneity of Immune checkpoint Signature (HIS) and resulted in immunotherapeutic resistance. Interestingly, overexpressing one pivotal immune checkpoint in a tumor hindered the upregulation of a majority of other immune checkpoint genes during tumor progression via suppressing interferon γ, resulting in HIS-low. Indeed, PD-L1 high-expression sensitized baseline large tumors to anti-PD1 therapy without altering the sensitivity of baseline small tumors. In line with these preclinical results, a retrospective analysis of a phase III study involving patients with non-small cell lung cancer (NSCLC) revealed that PD-L1 tumor proportion score (TPS) ≥ 50% more reliably predicted therapeutic response in NSCLC patients with baseline tumor volume (BTV)-large compared to patients with BTV-small. Notably, TPS combined with BTV significantly improved the predictive accuracy. Collectively, the data suggest that HIS reflects the dynamic features of tumor immune evasion and dictates the selective efficacy of ICB in a tumor size-dependent manner, providing a potential novel strategy to improve precision ICB. These findings highlight the application of ICB to earlier stages of cancer patients. The integration of PD-L1 with BTV may immediately improve patient stratification and prediction performance in the clinic.

Radiotherapy (RT) resistance in head and neck squamous cell carcinoma (HNSCC) significantly hampers local control and patient prognosis. This study investigated the efficacy and molecular mechanisms of high-energy X-ray-based ultra-high dose rate radiotherapy (UHDR-RT) in overcoming RT resistance. The established RT-resistant HNSCC cell lines and animal models were subjected to UHDR-RT or conventional RT (Conv-RT) via a high-power rhodotron accelerator. Cellular assays assessed the malignant phenotype, viability, and degree of DNA damage, whereas in vivo evaluations focused on tumor proliferation and the tumor immune microenvironment (TiME). Transcriptome sequencing and Olink proteomics were employed to explore the underlying mechanisms involved. In vitro experiments indicated that UHDR-RT suppressed radioresistant cell proliferation and invasion, while promoting apoptosis and exacerbating DNA damage. In contrast, its efficacy in radiosensitive cells was comparable to that of Conv-RT. In vivo studies using patient-derived xenograft nude mice models demonstrated that UHDR-RT only partially reversed RT resistance. Transcriptomic and proteomic analyses of C57BL/6J mice models revealed the predominant role of TiME modulating in reversing radioresistance. Immunofluorescence and flow cytometry confirmed increased CD8+ T cells and an increased M1/M2 macrophage ratio post-UHDR-RT. Mechanistically, UHDR-RT activated CD8+ T cells, which stimulated M1 macrophages through paracrine IFN-γ signaling, thereby enhancing TiME activation. Furthermore, the activated M1 macrophages secreted CXCL9, which in turn reactivated CD8+ T cells, forming a feedforward loop that amplified TiME activation. This study elucidates the dual role of UHDR-RT in directly inducing DNA damage and modulating the TiME, highlighting its potential in treating radioresistant HNSCC.

Oncolytic viruses have been considered promising cancer immunotherapies. However, oncovirotherapy agents impart durable responses in only a subset of cancer patients. Thus, exploring the cellular and molecular mechanisms underlying the heterogeneous responses in patients can provide guidance to develop more effective oncolytic virus therapies. Single-cell RNA sequencing (scRNA-seq) analysis of tumors responsive and non-responsive to oncovirotherapy revealed signatures of the tumor immune microenvironment associated with immune response. Thus, we designed and constructed an armed oncolytic virus, OV-5A, that expressed five genes with non-redundant functions. OV-5A treatment exhibits robust immune response against various tumors in multiple mouse models, peripheral blood mononuclear cell -patient-derived xenograft models, organoid-immune cell co-culture systems, and patient tissue sections by activating a cooperative innate-adaptive immune response against tumor cells. scRNA-seq analysis of complete responders and partial responders to OV-5A treatment guided the design of combination therapy of OV-5A. This data-driven approach paves an innovative way to rationalize the design of oncolytic virus and multi-agent combination therapies.

Fat mass and obesity-associated protein (FTO), an eraser of N6-methyadenosine (m6A), plays oncogenic roles in various cancers. However, its role in hepatocellular carcinoma (HCC) is unclear. Furthermore, small extracellular vesicles (sEVs, or exosomes) are critical mediators of tumourigenesis and metastasis, but the relationship between FTO-mediated m6A modification and sEVs in HCC is unknown.

Poly ADP-ribose polymerase inhibitors (PARPi) are first-line maintenance therapy for ovarian cancer and an alternative therapy for several other cancer types. However, PARPi-resistance is rising, and there is currently an unmet need to combat PARPi-resistant tumors. Here, we created an immunocompetent, PARPi-resistant mouse model to test the efficacy of combinatory PARPi and euchromatic histone methyltransferase 1/2 inhibitor (EHMTi) in the treatment of PARPi-resistant ovarian cancer. We discovered that inhibition of EHMT1/2 resensitizes cells to PARPi. Markedly, we show that single EHMTi and combinatory EHMTi/PARPi significantly reduced PARPi-resistant tumor burden and that this reduction is partially dependent on CD8 T cells. Altogether, our results show a low-toxicity drug that effectively treats PARPi-resistant ovarian cancer in an immune-dependent manner, supporting its entry into clinical development and potential incorporation of immunotherapy. Implications: Targeting the epigenome of therapy-resistant ovarian cancer induces an antitumor response mediated in part through an antitumor immune response.

Poly (ADP-ribose) Polymerase inhibitors (PARPi) have demonstrated remarkable clinical efficacy in treating ovarian cancer (OV) with BRCA1/2 mutations. However, drug resistance inevitably limits their clinical applications and there is an urgent need for improved therapeutic strategies to enhance the clinical utility of PARPi, such as Olaparib. Here, compelling evidence indicates that sensitivity of PARPi is associated with cell cycle dysfunction. Through high-throughput drug screening with a cell cycle kinase inhibitor library, XL413, a potent cell division cycle 7 (CDC7) inhibitor, is identified which can synergistically enhance the anti-tumor efficacy of Olaparib. Mechanistically, the combined administration of XL413 and Olaparib demonstrates considerable DNA damage and DNA replication stress, leading to increased sensitivity to Olaparib. Additionally, a robust type-I interferon response is triggered through the induction of the cGAS/STING signaling pathway. Using murine syngeneic tumor models, the combination treatment further demonstrates enhanced antitumor immunity, resulting in tumor regression. Collectively, this study presents an effective treatment strategy for patients with advanced OV by combining CDC7 inhibitors (CDC7i) and PARPi, offering a promising therapeutic approach for patients with limited response to PARPi.

The therapeutic potential of commensal microbes and their metabolites is promising in the functional cure of chronic hepatitis B virus (HBV) infection, which is defined as hepatitis B surface antigen (HBsAg) loss. Here, using both specific-pathogen-free and germ-free mice, we report that probiotics significantly promote the decline of HBsAg and inhibit HBV replication by enhancing intestinal homeostasis and provoking intrahepatic interferon (IFN)-γ+CD4+ T cell immune response. Depletion of CD4+ T cells or blockage of IFN-γ abolishes probiotics-mediated HBV inhibition. Specifically, probiotics-derived spermidine accumulates in the gut and transports to the liver, where it exhibits a similar anti-HBV effect. Mechanistically, spermidine enhances IFN-γ+CD4+ T cell immunity by autophagy. Strikingly, administration of probiotics in HBV patients reveals a preliminary trend to accelerate the decline of serum HBsAg. In conclusion, probiotics and their derived spermidine promote HBV clearance via autophagy-enhanced IFN-γ+CD4+ T cell immunity, highlighting the therapeutic potential of probiotics and spermidine for the functional cure of HBV patients.

Tumor-associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs) play a critical role in resistance to immunotherapy. In this study, we identified epidermal growth factor-like 6 (Egfl6) as a regulator of myeloid cell functions. Our analyses indicated that Egfl6, via binding with β3 integrins and activation of p38 and SYK signaling, acts as a chemotactic factor for myeloid cell migration and promotes their differentiation toward an immunosuppressive state. In syngeneic mouse models of ovarian cancer (OvCa), tumor expression of Egfl6 increased the intratumoral accumulation of polymorphonuclear (PMN) MDSCs and TAMs and their expression of immunosuppressive factors, including CXCL2, IL-10, and PD-L1. Consistent with this, in an immune 'hot' tumor model, Egfl6 expression eliminated response to anti-PD-L1 therapy, while Egfl6 neutralizing antibody decreased the accumulation of tumor-infiltrating CD206+ TAMs and PMN-MDSCs and restored the efficacy of anti-PD-L1 therapy. Supporting a role in human tumors, in human OvCa tissue samples, areas of high EGFL6 expression colocalized with myeloid cell infiltration. scRNA-Seq analyses revealed a correlation between EGFL6 and immune cell expression of immunosuppressive factors. Our data provide mechanistic insights into the oncoimmunologic functions of EGFL6 in mediating tumor immune suppression and identified EGFL6 as a potential therapeutic target to enhance immunotherapy in patients with OvCa.

Despite progress significant advances in immunotherapy for some solid tumors, pancreatic ductal adenocarcinoma (PDAC) remains unresponsive poorly responsive to such interventions, largely due to its highly immunosuppressive tumor microenvironment (TME) with limited CD8+ T cell infiltration. This study explores the role of the epigenetic factor Sin3B in the PDAC TME. Using murine PDAC models, we found that tumor cell-intrinsic Sin3B loss reshapes the TME, increasing CD8+ T cell infiltration and cytotoxicity, thus impeding tumor progression and enhancing sensitivity to anti-PD1 treatment. Sin3B-deficient tumor cells exhibited amplified CXCL9/10 secretion in response to Interferon-gamma (IFNγ), creating a positive feedback loop via the CXCL9/10-CXCR3 axis, thereby intensifying the anti-tumor immune response against PDAC. Mechanistically, extensive epigenetic regulation is uncovered by Sin3B loss, particularly enhanced H3K27Ac distribution on genes related to immune responses in PDAC cells. Consistent with the murine model findings, analysis of human PDAC samples revealed a significant inverse correlation between SIN3B levels and both CD8+ T cell infiltration and CXCL9/10 expression. Notebly, PDAC patients with lower SIN3B expression showed a more favorable response to anti-PD1 therapy. The findings suggest that targeting SIN3B can enhance cytotoxic T cell infiltration into the tumor site and improve immunotherapy efficacy in PDAC, offering potential avenues for therapeutic biomarker or target in this challenging disease.