Eradication of large established tumors in mice by combination immunotherapy that engages innate and adaptive immune responses

Engineering Dimeric EGFR-directed IgA Antibodies Reveals a Central Role of CD147 during Neutrophil-mediated Tumor Cell Killing of Head and Neck Squamous Cancer Cells

Human IgA Abs engage neutrophils for cancer immunotherapy more effectively than IgG Abs. Previous studies demonstrated that engineering approaches improved biochemical and functional properties. In this study, we report a novel, to our knowledge, IgA2 Ab against the epidermal growth factor receptor generated by protein engineering and polymerization. The resulting molecule demonstrated a covalent linkage of L and H chains and an effective polymerization by the joining chain. The engineered dimer outperformed its monomeric variant in functional experiments on Fab-mediated modes of action and binding to the Fc receptor. The capacity to engage neutrophils for Ab-dependent cell-mediated cytotoxicity (ADCC) of adherent growing target cancer cells was cell line dependent. Although the engineered dimer displayed a long-term efficacy against the vulva carcinoma cell line A431, there was a notable in-efficacy against human papillomavirus (HPV)- head and neck squamous cell carcinoma (HNSCC) cell lines. However, the highly engineered IgA Abs triggered a neutrophil-mediated cytotoxicity against HPV+ HNSCC cell lines. Short-term ADCC efficacy correlated with the target cells' epidermal growth factor receptor expression and the ability of cancer cell-conditioned media to enhance the CD147 surface level on neutrophils. Notably, the HPV+ HNSCC cell lines demonstrated a significant increment in releasing soluble CD147 and a reduced induction of membranous CD147 on neutrophils compared with HPV- cells. Although membranous CD147 on neutrophils may impair proper IgA-Fc receptor binding, soluble CD147 enhanced the IgA-neutrophil-mediated ADCC in a dose-dependent manner. Thus, engineering IgA Abs and impedance-based ADCC assays provided valuable information regarding the target-effector cell interaction and identified CD147 as a putative critical parameter for neutrophil-mediated cytotoxicity.

Metabolic Reprogramming of Tumor-Associated Macrophages Using Glutamine Antagonist JHU083 Drives Tumor Immunity in Myeloid-Rich Prostate and Bladder Cancers

Glutamine metabolism in tumor microenvironments critically regulates antitumor immunity. Using the glutamine-antagonist prodrug JHU083, we report potent tumor growth inhibition in urologic tumors by JHU083-reprogrammed tumor-associated macrophages (TAMs) and tumor-infiltrating monocytes. We show JHU083-mediated glutamine antagonism in tumor microenvironments induced by TNF, proinflammatory, and mTORC1 signaling in intratumoral TAM clusters. JHU083-reprogrammed TAMs also exhibited increased tumor cell phagocytosis and diminished proangiogenic capacities. In vivo inhibition of TAM glutamine consumption resulted in increased glycolysis, a broken tricarboxylic acid (TCA) cycle, and purine metabolism disruption. Although the antitumor effect of glutamine antagonism on tumor-infiltrating T cells was moderate, JHU083 promoted a stem cell-like phenotype in CD8+ T cells and decreased the abundance of regulatory T cells. Finally, JHU083 caused a global shutdown in glutamine-utilizing metabolic pathways in tumor cells, leading to reduced HIF-1α, c-MYC phosphorylation, and induction of tumor cell apoptosis, all key antitumor features. Altogether, our findings demonstrate that targeting glutamine with JHU083 led to suppressed tumor growth as well as reprogramming of immunosuppressive TAMs within prostate and bladder tumors that promoted antitumor immune responses. JHU083 can offer an effective therapeutic benefit for tumor types that are enriched in immunosuppressive TAMs.

Engineering Versatile Bacteria-Derived Outer Membrane Vesicles: An Adaptable Platform for Advancing Cancer Immunotherapy

In recent years, cancer immunotherapy has undergone a transformative shift toward personalized and targeted therapeutic strategies. Bacteria-derived outer membrane vesicles (OMVs) have emerged as a promising and adaptable platform for cancer immunotherapy due to their unique properties, including natural immunogenicity and the ability to be engineered for specific therapeutic purposes. In this review, a comprehensive overview is provided of state-of-the-art techniques and methodologies employed in the engineering of versatile OMVs for cancer immunotherapy. Beginning by exploring the biogenesis and composition of OMVs, unveiling their intrinsic immunogenic properties for therapeutic appeal. Subsequently, innovative approaches employed to engineer OMVs are delved into, ranging from the genetic engineering of parent bacteria to the incorporation of functional molecules. The importance of rational design strategies is highlighted to enhance the immunogenicity and specificity of OMVs, allowing tailoring for diverse cancer types. Furthermore, insights into clinical studies and potential challenges utilizing OMVs as cancer vaccines or adjuvants are also provided, offering a comprehensive assessment of the current landscape and future prospects. Overall, this review provides valuable insights for researchers involved in the rapidly evolving field of cancer immunotherapy, offering a roadmap for harnessing the full potential of OMVs as a versatile and adaptable platform for cancer treatment.

PIKfyve, expressed by CD11c-positive cells, controls tumor immunity

Cancer treatment continues to shift from utilizing traditional therapies to targeted ones, such as protein kinase inhibitors and immunotherapy. Mobilizing dendritic cells (DC) and other myeloid cells with antigen presenting and cancer cell killing capacities is an attractive but not fully exploited approach. Here, we show that PIKFYVE is a shared gene target of clinically relevant protein kinase inhibitors and high expression of this gene in DCs is associated with poor patient response to immune checkpoint blockade (ICB) therapy. Genetic and pharmacological studies demonstrate that PIKfyve ablation enhances the function of CD11c+ cells (predominantly dendritic cells) via selectively altering the non-canonical NF-κB pathway. Both loss of Pikfyve in CD11c+ cells and treatment with apilimod, a potent and specific PIKfyve inhibitor, restrained tumor growth, enhanced DC-dependent T cell immunity, and potentiated ICB efficacy in tumor-bearing mouse models. Furthermore, the combination of a vaccine adjuvant and apilimod reduced tumor progression in vivo. Thus, PIKfyve negatively regulates the function of CD11c+ cells, and PIKfyve inhibition has promise for cancer immunotherapy and vaccine treatment strategies.

Disulfidptosis-related lncRNAs signature predicting prognosis and immunotherapy effect in lung adenocarcinoma

PURPOSE

Lung adenocarcinoma (LUAD) is a prevalent malignant tumor worldwide, with high incidence and mortality rates. However, there is still a lack of specific and sensitive biomarkers for its early diagnosis and targeted treatment. Disulfidptosis is a newly identified mode of cell death that is characteristic of disulfide stress. Therefore, exploring the correlation between disulfidptosis-related long non-coding RNAs (DRGs-lncRNAs) and patient prognosis can provide new molecular targets for LUAD patients.

METHODS

The study analysed the transcriptome data and clinical data of LUAD patients in The Cancer Genome Atlas (TCGA) database, gene co-expression, and univariate Cox regression methods were used to screen for DRGs-lncRNAs related to prognosis. The risk score model of lncRNA was established by univariate and multivariate Cox regression models. TIMER, CIBERSORT, CIBERSORT-ABS, and other methods were used to analyze immune infiltration and further evaluate immune function analysis, immune checkpoints, and drug sensitivity. Real-time polymerase chain reaction (RT-PCR) was performed to detect the expression of DRGs-lncRNAs in LUAD cell lines.

RESULTS

A total of 108 lncRNAs significantly associated with disulfidptosis were identified. A prognostic model was constructed by screening 10 lncRNAs with independent prognostic significance through single-factor Cox regression analysis, LASSO regression analysis, and multiple-factor Cox regression analysis. Survival analysis of patients through the prognostic model showed that there were obvious survival differences between the high- and low-risk groups. The risk score of the prognostic model can be used as an independent prognostic factor independent of other clinical traits, and the risk score increases with stage. Further analysis showed that the prognostic model was also different from tumor immune cell infiltration, immune function, and immune checkpoint genes in the high- and low-risk groups. Chemotherapy drug susceptibility analysis showed that high-risk patients were more sensitive to Paclitaxel, 5-Fluorouracil, Gefitinib, Docetaxel, Cytarabine, and Cisplatin. Additionally, RT-PCR analysis demonstrated differential expression of DRGs-lncRNAs between LUAD cell lines and the human bronchial epithelial cell line.

CONCLUSIONS

The prognostic model of DRGs-lncRNAs constructed in this study has certain accuracy and reliability in predicting the survival prognosis of LUAD patients, and provides clues for the interaction between disulfidptosis and LUAD immunotherapy.

MHC-II presentation by oral Langerhans cells impacts intraepithelial Tc17 abundance and Candida albicans oral infection via CD4 T cells

In a murine model (LCΔMHC-II) designed to abolish MHC-II expression in Langerhans cells (LCs), ∼18% of oral LCs retain MHC-II, yet oral mucosal CD4 T cells numbers are unaffected. In LCΔMHC-II mice, we now show that oral intraepithelial conventional CD8αβ T cell numbers expand 30-fold. Antibody-mediated ablation of CD4 T cells in wild-type mice also resulted in CD8αβ T cell expansion in the oral mucosa. Therefore, we hypothesize that MHC class II molecules uniquely expressed on Langerhans cells mediate the suppression of intraepithelial resident-memory CD8 T cell numbers via a CD4 T cell-dependent mechanism. The expanded oral CD8 T cells co-expressed CD69 and CD103 and the majority produced IL-17A [CD8 T cytotoxic (Tc)17 cells] with a minority expressing IFN-γ (Tc1 cells). These oral CD8 T cells showed broad T cell receptor Vβ gene usage indicating responsiveness to diverse oral antigens. Generally supporting Tc17 cells, transforming growth factor-β1 (TGF-β1) increased 4-fold in the oral mucosa. Surprisingly, blocking TGF-β1 signaling with the TGF-R1 kinase inhibitor, LY364947, did not reduce Tc17 or Tc1 numbers. Nonetheless, LY364947 increased γδ T cell numbers and decreased CD49a expression on Tc1 cells. Although IL-17A-expressing γδ T cells were reduced by 30%, LCΔMHC-II mice displayed greater resistance to Candida albicans in early stages of oral infection. These findings suggest that modulating MHC-II expression in oral LC may be an effective strategy against fungal infections at mucosal surfaces counteracted by IL-17A-dependent mechanisms.

Batf3+ DCs and the 4-1BB/4-1BBL axis are required at the effector phase in the tumor microenvironment for PD-1/PD-L1 blockade efficacy

The cellular source of positive signals that reinvigorate T cells within the tumor microenvironment (TME) for the therapeutic efficacy of programmed death-1 (PD-1)/programmed death-ligand 1 (PD-L1) blockade has not been clearly defined. We now show that Batf3-lineage dendritic cells (DCs) are essential in this process. Flow cytometric analysis, gene-targeted mice, and blocking antibody studies revealed that 4-1BBL is a major positive co-stimulatory signal provided by these DCs within the TME that translates to CD8+ T cell functional reinvigoration and tumor regression. Immunofluorescence and spatial transcriptomics on human tumor samples revealed clustering of Batf3+ DCs and CD8+ T cells, which correlates with anti-PD-1 efficacy. In addition, proximity to Batf3+ DCs within the TME is associated with CD8+ T cell transcriptional states linked to anti-PD-1 response. Our results demonstrate that Batf3+ DCs within the TME are critical for PD-1/PD-L1 blockade efficacy and indicate a major role for the 4-1BB/4-1BB ligand (4-1BBL) axis during this process.

Modeling T cell temporal response to cancer immunotherapy rationalizes development of combinatorial treatment protocols

Successful immunotherapy relies on triggering complex responses involving T cell dynamics in tumors and the periphery. Characterizing these responses remains challenging using static human single-cell atlases or mouse models. To address this, we developed a framework for in vivo tracking of tumor-specific CD8+ T cells over time and at single-cell resolution. Our tools facilitate the modeling of gene program dynamics in the tumor microenvironment (TME) and the tumor-draining lymph node (tdLN). Using this approach, we characterize two modes of anti-programmed cell death protein 1 (PD-1) activity, decoupling induced differentiation of tumor-specific activated precursor cells from conventional type 1 dendritic cell (cDC1)-dependent proliferation and recruitment to the TME. We demonstrate that combining anti-PD-1 therapy with anti-4-1BB agonist enhances the recruitment and proliferation of activated precursors, resulting in tumor control. These data suggest that effective response to anti-PD-1 therapy is dependent on sufficient influx of activated precursor CD8+ cells to the TME and highlight the importance of understanding system-level dynamics in optimizing immunotherapies.

Controlled Refolding of Denatured IL-12 Using In Situ Antigen-Capturing Nanochaperone Remarkably Reduces the Systemic Toxicity and Enhances Cancer Immunotherapy

Cytokines are powerful in cancer immunotherapy, however, their therapeutic potential is limited by the severe systemic toxicity. Here a potent strategy to reduce the toxicity of systemic cytokine therapy by delivering its denatured form using a finely designed nanochaperone, is described. It is demonstrated that even if the denatured protein cargos are occasionally released under normal physiological conditions they are still misfolded, while can effectively refold into native states and release to function in tumor microenvironment. Consequently, the systemic toxicity of cytokines is nearly completely overcome. Moreover, an immunogenic cell death (ICD)-inducing chemotherapeutic is further loaded and delivered to tumor using this nanochaperone to trigger the release of tumor-associated antigens (TAAs) that are subsequently captured in situ by nanochaperone and then reflows into lymph nodes (LNs) to promote antigen cross-presentation. This optimized personalized nanochaperone-vaccine demonstrates unprecedented suppressive effects against large, advanced tumors, and in combination with immune checkpoint blockade (ICB) therapy results in a significant abscopal effect and inhibition of postoperative tumor recurrence and metastasis. Hence, this approach provides a simple and universal delivery strategy to reduce the systemic toxicities of cytokines, as well as provides a robust personalized cancer vaccination platform, which may find wide applications in cancer immunotherapy.

Targeting Dectin-1 and or VISTA enhances anti-tumor immunity in melanoma but not colorectal cancer model

PURPOSE

Acquired resistance to immune checkpoint blockers (ICBs) is a major barrier in cancer treatment, emphasizing the need for innovative strategies. Dectin-1 (gene Clec7a) is a C-type lectin receptor best known for its ability to recognize β-glucan-rich structures in fungal cell walls. While Dectin-1 is expressed in myeloid cells and tumor cells, its significance in cancer remains the subject of controversy.

METHODS

Using Celc7a-/- mice and curdlan administration to stimulate Dectin-1 signaling, we explored its impact. VISTA KO mice were employed to assess VISTA's role, and bulk RNAseq analyzed curdlan effects on neutrophils.

RESULTS

Our findings reveal myeloid cells as primary Dectin-1 expressing cells in the tumor microenvironment (TME), displaying an activated phenotype. Strong Dectin-1 co-expression/co-localization with VISTA and PD-L1 in TME myeloid cells was observed. While Dectin-1 deletion lacked protective effects, curdlan stimulation significantly curtailed B16-F10 tumor progression. RNAseq and pathway analyses supported curdlan's role in triggering a cascade of events leading to increased production of pro-inflammatory mediators, potentially resulting in the recruitment and activation of immune cells. Moreover, we identified a heterogeneous subset of Dectin-1+ effector T cells in the TME. Similar to mice, human myeloid cells are the prominent cells expressing Dectin-1 in cancer patients.

CONCLUSION

Our study proposes Dectin-1 as a potential adjunctive target with ICBs, orchestrating a comprehensive engagement of innate and adaptive immune responses in melanoma. This innovative approach holds promise for overcoming acquired resistance to ICBs in cancer treatment, offering avenues for further exploration and development.

Immunomodulatory Peptides for Tumor Treatment

Peptides exhibit various biological activities, including biorecognition, cell targeting, and tumor penetration, and can stimulate immune cells to elicit immune responses for tumor immunotherapy. Peptide self-assemblies and peptide-functionalized nanocarriers can reduce the effect of various biological barriers and the degradation by peptidases, enhancing the efficiency of peptide delivery and improving antitumor immune responses. To date, the design and development of peptides with various functionalities have been extensively reviewed for enhanced chemotherapy; however, peptide-mediated tumor immunotherapy using peptides acting on different immune cells, to the knowledge, has not yet been summarized. Thus, this work provides a review of this emerging subject of research, focusing on immunomodulatory anticancer peptides. This review introduces the role of peptides in the immunomodulation of innate and adaptive immune cells, followed by a link between peptides in the innate and adaptive immune systems. The peptides are discussed in detail, following a classification according to their effects on different innate and adaptive immune cells, as well as immune checkpoints. Subsequently, two delivery strategies for peptides as drugs are presented: peptide self-assemblies and peptide-functionalized nanocarriers. The concluding remarks regarding the challenges and potential solutions of peptides for tumor immunotherapy are presented.

Combining SiRPα decoy-coengineered T cells and antibodies augments macrophage-mediated phagocytosis of tumor cells

The adoptive transfer of T cell receptor-engineered (TCR-engineered) T cells (ACT) targeting the HLA-A2-restricted cancer-testis epitope NY-ESO-1157-165 (A2/NY) has yielded favorable clinical responses against several cancers. Two approaches to improve ACT are TCR affinity optimization and T cell coengineering to express immunomodulatory molecules that can exploit endogenous immunity. By computational design we previously developed a panel of binding-enhanced A2/NY-TCRs including A97L, which augmented the in vitro function of gene-modified T cells as compared with WT. Here, we demonstrated higher persistence and improved tumor control by A97L-T cells. In order to harness macrophages in tumors, we further coengineered A97L-T cells to secrete a high-affinity signal regulatory protein α (SiRPα) decoy (CV1) that blocks CD47. While CV1-Fc-coengineered A97L-T cells mediated significantly better control of tumor outgrowth and survival in Winn assays, in subcutaneous xenograft models the T cells, coated by CV1-Fc, were depleted. Importantly, there was no phagocytosis of CV1 monomer-coengineered T cells by human macrophages. Moreover, avelumab and cetuximab enhanced macrophage-mediated phagocytosis of tumor cells in vitro in the presence of CV1 and improved tumor control upon coadministration with A97L-T cells. Taken together, our study indicates important clinical promise for harnessing macrophages by combining CV1-coengineered TCR-T cells with targeted antibodies to direct phagocytosis against tumor cells.

Noncovalently particle-anchored cytokines with prolonged tumor retention safely elicit potent antitumor immunity

Preclinical studies have shown that immunostimulatory cytokines elicit antitumor immune responses but their clinical use is limited by severe immune-related adverse events upon systemic administration. Here, we report a facile and versatile strategy for noncovalently anchoring potent Fc-fused cytokine molecules to the surface of size-discrete particles decorated with Fc-binding peptide for local administration. Following intratumoral injection, particle-anchored Fc cytokines exhibit size-dependent intratumoral retention. The 1-micrometer particle prolongs intratumoral retention of Fc cytokine for over a week and has minimal systemic exposure, thereby eliciting antitumor immunity while eliminating systemic toxicity caused by circulating cytokines. In addition, the combination of these particle-anchored cytokines with immune checkpoint blockade antibodies safely promotes tumor regression in various syngeneic tumor models and genetically engineered murine tumor models and elicits systemic antitumor immunity against tumor rechallenge. Our formulation strategy renders a safe and tumor-agnostic approach that uncouples cytokines' immunostimulatory properties from their systemic toxicities for potential clinical application.

Biomaterial engineering strategies for B cell immunity modulations

B cell immunity has a penetrating effect on human health and diseases. Therapeutics aiming to modulate B cell immunity have achieved remarkable success in combating infections, autoimmunity, and malignancies. However, current treatments still face significant limitations in generating effective long-lasting therapeutic B cell responses for many conditions. As the understanding of B cell biology has deepened in recent years, clearer regulation networks for B cell differentiation and antibody production have emerged, presenting opportunities to overcome current difficulties and realize the full therapeutic potential of B cell immunity. Biomaterial platforms have been developed to leverage these emerging concepts to augment therapeutic humoral immunity by facilitating immunogenic reagent trafficking, regulating T cell responses, and modulating the immune microenvironment. Moreover, biomaterial engineering tools have also advanced our understanding of B cell biology, further expediting the development of novel therapeutics. In this review, we will introduce the general concept of B cell immunobiology and highlight key biomaterial engineering strategies in the areas including B cell targeted antigen delivery, sustained B cell antigen delivery, antigen engineering, T cell help optimization, and B cell suppression. We will also discuss our perspective on future biomaterial engineering opportunities to leverage humoral immunity for therapeutics.

Natural Killer Cells Do Not Attenuate a Mouse-Adapted SARS-CoV-2-Induced Disease in Rag2-/- Mice

This study investigates the roles of T, B, and Natural Killer (NK) cells in the pathogenesis of severe COVID-19, utilizing mouse-adapted SARS-CoV-2-MA30 (MA30). To evaluate this MA30 mouse model, we characterized MA30-infected C57BL/6 mice (B6) and compared them with SARS-CoV-2-WA1 (an original SARS-CoV-2 strain) infected K18-human ACE2 (K18-hACE2) mice. We found that the infected B6 mice developed severe peribronchial inflammation and rapid severe pulmonary edema, but less lung interstitial inflammation than the infected K18-hACE2 mice. These pathological findings recapitulate some pathological changes seen in severe COVID-19 patients. Using this MA30-infected mouse model, we further demonstrate that T and/or B cells are essential in mounting an effective immune response against SARS-CoV-2. This was evident as Rag2-/- showed heightened vulnerability to infection and inhibited viral clearance. Conversely, the depletion of NK cells did not significantly alter the disease course in Rag2-/- mice, underscoring the minimal role of NK cells in the acute phase of MA30-induced disease. Together, our results indicate that T and/or B cells, but not NK cells, mitigate MA30-induced disease in mice and the infected mouse model can be used for dissecting the pathogenesis and immunology of severe COVID-19.

Enhancing cancer immunotherapy with photodynamic therapy and nanoparticle: making tumor microenvironment hotter to make immunotherapeutic work better

Cancer immunotherapy has made tremendous advancements in treating various malignancies. The biggest hurdle to successful immunotherapy would be the immunosuppressive tumor microenvironment (TME) and low immunogenicity of cancer cells. To make immunotherapy successful, the 'cold' TME must be converted to 'hot' immunostimulatory status to activate residual host immune responses. To this end, the immunosuppressive equilibrium in TME should be broken, and immunogenic cancer cell death ought to be induced to stimulate tumor-killing immune cells appropriately. Photodynamic therapy (PDT) is an efficient way of inducing immunogenic cell death (ICD) of cancer cells and disrupting immune-restrictive tumor tissues. PDT would trigger a chain reaction that would make the TME 'hot' and have ICD-induced tumor antigens presented to immune cells. In principle, the strategic combination of PDT and immunotherapy would synergize to enhance therapeutic outcomes in many intractable tumors. Novel technologies employing nanocarriers were developed to deliver photosensitizers and immunotherapeutic to TME efficiently. New-generation nanomedicines have been developed for PDT immunotherapy in recent years, which will accelerate clinical applications.

Inhalable extracellular vesicle delivery of IL-12 mRNA to treat lung cancer and promote systemic immunity

Lung carcinoma is one of the most common cancers and has one of the lowest survival rates in the world. Cytokines such as interleukin-12 (IL-12) have demonstrated considerable potential as robust tumour suppressors. However, their applications are limited due to off-target toxicity. Here we report on a strategy involving the inhalation of IL-12 messenger RNA, encapsulated within extracellular vesicles. Inhalation and preferential uptake by cancer cells results in targeted delivery and fewer systemic side effects. The IL-12 messenger RNA generates interferon-γ production in both innate and adaptive immune-cell populations. This activation consequently incites an intense activation state in the tumour microenvironment and augments its immunogenicity. The increased immune response results in the expansion of tumour cytotoxic immune effector cells, the formation of immune memory, improved antigen presentation and tumour-specific T cell priming. The strategy is demonstrated against primary neoplastic lesions and provides profound protection against subsequent tumour rechallenge. This shows the potential for locally delivered cytokine-based immunotherapies to address orthotopic and metastatic lung tumours.

Human Tumor-Associated Macrophages and Neutrophils Regulate Antitumor Antibody Efficacy through Lethal and Sublethal Trogocytosis

The clinical benefits of tumor-targeting antibodies (tAb) are modest in solid human tumors. The efficacy of many tAbs is dependent on Fc receptor (FcR)-expressing leukocytes that bind Fc fragments of tAb. Tumor-associated macrophages (TAM) and neutrophils (TAN) represent the majority of FcR+ effectors in solid tumors. A better understanding of the mechanisms by which TAMs and TANs regulate tAb response could help improve the efficacy of cancer treatments. Here, we found that myeloid effectors interacting with tAb-opsonized lung cancer cells used antibody-dependent trogocytosis (ADT) but not antibody-dependent phagocytosis. During this process, myeloid cells "nibbled off" tumor cell fragments containing tAb/targeted antigen (tAg) complexes. ADT was only tumoricidal when the tumor cells expressed high levels of tAg and the effectors were present at high effector-to-tumor ratios. If either of these conditions were not met, which is typical for solid tumors, ADT was sublethal. Sublethal ADT, mainly mediated by CD32hiCD64hi TAM, led to two outcomes: (i) removal of surface tAg/tAb complexes from the tumor that facilitated tumor cell escape from the tumoricidal effects of tAb; and (ii) acquisition of bystander tAgs by TAM with subsequent cross-presentation and stimulation of tumor-specific T-cell responses. CD89hiCD32loCD64lo peripheral blood neutrophils (PBN) and TAN stimulated tumor cell growth in the presence of the IgG1 anti-EGFR Ab cetuximab; however, IgA anti-EGFR Abs triggered the tumoricidal activity of PBN and negated the stimulatory effect of TAN. Overall, this study provides insights into the mechanisms by which myeloid effectors mediate tumor cell killing or resistance during tAb therapy.

SIGNIFICANCE

The elucidation of the conditions and mechanisms by which human FcR+ myeloid effectors mediate cancer cell resistance and killing during antibody treatment could help develop improved strategies for treating solid tumors.

Circulating immunotherapy strategy based on pyroptosis and STING pathway: Mn-loaded paclitaxel prodrug nanoplatform against tumor progression and metastasis

Immunotherapy has emerged as a promising strategy against tumors. However, its efficacy is limited by low immunogenicity, poor antigen presentation, and inadequate lymphocyte infiltration. Herein, we develop a nanoplatform (Mn-HSP) loaded with manganese ions (Mn2+) and paclitaxel (PTX) prodrug based on hyaluronic acid. PTX in Mn-HSP induces DNA damage and pyroptosis to release tumor-associated antigens (TAAs), enhancing tumor-specific adaptive immunity. Meanwhile, Mn2+ in Mn-HSP, together with PTX-induced DNA damage, activates the stimulator of interferon gene (STING) pathway to amplify innate immunity. Mn-HSP combines with adaptive and innate immunity, effectively enhancing the presentation of antigen-presenting cells (APCs) and promoting tumor infiltration of cytotoxic T lymphocytes (CTLs). In turn, the granzyme B (GZMB) secreted by CTLs triggers pyroptosis again, thereby establishing a "circulating immunotherapy" against tumors. Our results demonstrate that Mn-HSP efficiently inhibits primary breast tumors, as well as rechallenge tumors and lung metastasis in vivo. Therefore, the circulating immunotherapy that combines pyroptosis mediated adaptive immunity and STING pathway amplified innate immunity provides a novel strategy for enhancing tumor immunotherapy.

PIKfyve controls dendritic cell function and tumor immunity

The modern armamentarium for cancer treatment includes immunotherapy and targeted therapy, such as protein kinase inhibitors. However, the mechanisms that allow cancer-targeting drugs to effectively mobilize dendritic cells (DCs) and affect immunotherapy are poorly understood. Here, we report that among shared gene targets of clinically relevant protein kinase inhibitors, high PIKFYVE expression was least predictive of complete response in patients who received immune checkpoint blockade (ICB). In immune cells, high PIKFYVE expression in DCs was associated with worse response to ICB. Genetic and pharmacological studies demonstrated that PIKfyve ablation enhanced DC function via selectively altering the alternate/non-canonical NF-κB pathway. Both loss of Pikfyve in DCs and treatment with apilimod, a potent and specific PIKfyve inhibitor, restrained tumor growth, enhanced DC-dependent T cell immunity, and potentiated ICB efficacy in tumor-bearing mouse models. Furthermore, the combination of a vaccine adjuvant and apilimod reduced tumor progression in vivo. Thus, PIKfyve negatively controls DCs, and PIKfyve inhibition has promise for cancer immunotherapy and vaccine treatment strategies.

CD8+ T cell priming that is required for curative intratumorally anchored anti-4-1BB immunotherapy is constrained by Tregs

Although co-stimulation of T cells with agonist antibodies targeting 4-1BB (CD137) improves antitumor immune responses in preclinical studies, clinical success has been limited by on-target, off-tumor activity. Here, we report the development of a tumor-anchored ɑ4-1BB agonist (ɑ4-1BB-LAIR), which consists of a ɑ4-1BB antibody fused to the collagen-binding protein LAIR. While combination treatment with an antitumor antibody (TA99) shows only modest efficacy, simultaneous depletion of CD4+ T cells boosts cure rates to over 90% of mice. Mechanistically, this synergy depends on ɑCD4 eliminating tumor draining lymph node regulatory T cells, resulting in priming and activation of CD8+ T cells which then infiltrate the tumor microenvironment. The cytotoxic program of these newly primed CD8+ T cells is then supported by the combined effect of TA99 and ɑ4-1BB-LAIR. The combination of TA99 and ɑ4-1BB-LAIR with a clinically approved ɑCTLA-4 antibody known for enhancing T cell priming results in equivalent cure rates, which validates the mechanistic principle, while the addition of ɑCTLA-4 also generates robust immunological memory against secondary tumor rechallenge. Thus, our study establishes the proof of principle for a clinically translatable cancer immunotherapy.

Engineering approaches for innate immune-mediated tumor microenvironment remodeling

Cancer immunotherapy offers transformative promise particularly for the treatment of lethal cancers, since a correctly trained immune system can comprehensively orchestrate tumor clearance with no need for continued therapeutic intervention. Historically, the majority of immunotherapies have been T cell-focused and have included immune checkpoint inhibitors, chimeric antigen receptor T cells, and T-cell vaccines. Unfortunately T-cell-focused therapies have failed to achieve optimal efficacy in most solid tumors largely because of a highly immunosuppressed 'cold' or immune-excluded tumor microenvironment (TME). Recently, a rapidly growing treatment paradigm has emerged that focuses on activation of tumor-resident innate antigen-presenting cells, such as dendritic cells and macrophages, which can drive a proinflammatory immune response to remodel the TME from 'cold' or immune-excluded to 'hot'. Early strategies for TME remodeling centered on free cytokines and agonists, but these approaches have faced significant hurdles in both delivery and efficacy. Systemic toxicity from off-target inflammation is a paramount concern in these therapies. To address this critical gap, engineering approaches have provided the opportunity to add 'built-in' capabilities to cytokines, agonists, and other therapeutic agents to mediate improved delivery and efficacy. Such capabilities have included protective encapsulation to shield them from degradation, targeting to direct them with high specificity to tumors, and co-delivery strategies to harness synergistic proinflammatory pathways. Here, we review innate immune-mediated TME remodeling engineering approaches that focus on cytokines, innate immune agonists, immunogenic viruses, and cell-based methods, highlighting emerging preclinical approaches and strategies that are either being tested in clinical trials or already Food and Drug Administration approved.

Kupffer cells abrogate homing and repopulation of allogeneic hepatic progenitors in injured liver site

BACKGROUND

Allogeneic hepatocyte transplantation is an emerging approach to treat acute liver defects. However, durable engraftment of the transplanted cells remains a daunting task, as they are actively cleared by the recipient's immune system. Therefore, a detailed understanding of the innate or adaptive immune cells-derived responses against allogeneic transplanted hepatic cells is the key to rationalize cell-based therapies.

METHODS

Here, we induced an acute inflammatory regenerative niche (3-96 h) on the surface of the liver by the application of cryo-injury (CI) to systematically evaluate the innate immune response against transplanted allogeneic hepatic progenitors in a sustained micro-inflammatory environment.

RESULTS

The resulting data highlighted that the injured site was significantly repopulated by alternating numbers of innate immune cells, including neutrophils, monocytes and Kupffer cells (KCs), from 3 to 96 h. The transplanted allo-HPs, engrafted 6 h post-injury, were collectively eliminated by the innate immune response within 24 h of transplantation. Selective depletion of the KCs demonstrated a delayed recruitment of monocytes from day 2 to day 6. In addition, the intrasplenic engraftment of the hepatic progenitors 54 h post-transplantation was dismantled by KCs, while a time-dependent better survival and translocation of the transplanted cells into the injured site could be observed in samples devoid of KCs.

CONCLUSION

Overall, this study provides evidence that KCs ablation enables a better survival and integration of allo-HPs in a sustained liver inflammatory environment, having implications for rationalizing the cell-based therapeutic interventions against liver defects.

Targeting myeloperoxidase limits myeloid cell immunosuppression enhancing immune checkpoint therapy for pancreatic cancer

Pancreatic ductal adenocarcinoma is a devastating disease characterized by an extreme resistance to current therapies, including immune checkpoint therapy. The limited success of immunotherapies can be attributed to a highly immunosuppressive pancreatic cancer microenvironment characterized by an extensive infiltration of immune suppressing myeloid cells. While there are several pathways through which myeloid cells contribute to immunosuppression, one important mechanism is the increased production of reactive oxygen species. Here, we evaluated the contribution of myeloperoxidase, a myeloid-lineage restricted enzyme and primary source of reactive oxygen species, to regulate immune checkpoint therapy response in preclinical pancreatic cancer models. We compared treatment outcome, immune composition and characterized myeloid cells using wild-type, myeloperoxidase-deficient, and myeloperoxidase inhibitor treated wild-type mice using established subcutaneous pancreatic cancer models. Loss of host myeloperoxidase and pharmacological inhibition of myeloperoxidase in combination with immune checkpoint therapy significantly delayed tumor growth. The tumor microenvironment and systemic immune landscape demonstrated significant decreases in myeloid cells, exhausted T cells and T regulatory cell subsets when myeloperoxidase was deficient. Loss of myeloperoxidase in isolated myeloid cell subsets from tumor-bearing mice resulted in decreased reactive oxygen species production and T cell suppression. These data suggest that myeloperoxidase contributes to an immunosuppressive microenvironment and immune checkpoint therapy resistance where myeloperoxidase inhibitors have the potential to enhance immunotherapy response. Repurposing myeloperoxidase specific inhibitors may provide a promising therapeutic strategy to expand therapeutic options for pancreatic cancer patients to include immunotherapies.

Immune cell networking in solid tumors: focus on macrophages and neutrophils

The tumor microenvironment is composed of tumor cells, stromal cells and leukocytes, including innate and adaptive immune cells, and represents an ecological niche that regulates tumor development and progression. In general, inflammatory cells are considered to contribute to tumor progression through various mechanisms, including the formation of an immunosuppressive microenvironment. Macrophages and neutrophils are important components of the tumor microenvironment and can act as a double-edged sword, promoting or inhibiting the development of the tumor. Targeting of the immune system is emerging as an important therapeutic strategy for cancer patients. However, the efficacy of the various immunotherapies available is still limited. Given the crucial importance of the crosstalk between macrophages and neutrophils and other immune cells in the formation of the anti-tumor immune response, targeting these interactions may represent a promising therapeutic approach against cancer. Here we will review the current knowledge of the role played by macrophages and neutrophils in cancer, focusing on their interaction with other immune cells.

CAR-T cell therapy targeting surface expression of TYRP1 to treat cutaneous and rare melanoma subtypes

A major limitation to developing chimeric antigen receptor (CAR)-T cell therapies for solid tumors is identifying surface proteins highly expressed in tumors but not in normal tissues. Here, we identify Tyrosinase Related Protein 1 (TYRP1) as a CAR-T cell therapy target to treat patients with cutaneous and rare melanoma subtypes unresponsive to immune checkpoint blockade. TYRP1 is primarily located intracellularly in the melanosomes, with a small fraction being trafficked to the cell surface via vesicular transport. We develop a highly sensitive CAR-T cell therapy that detects surface TYRP1 in tumor cells with high TYRP1 overexpression and presents antitumor activity in vitro and in vivo in murine and patient-derived cutaneous, acral and uveal melanoma models. Furthermore, no systemic or off-tumor severe toxicities are observed in an immunocompetent murine model. The efficacy and safety profile of the TYRP1 CAR-T cell therapy supports the ongoing preparation of a phase I clinical trial.

Lymph Node-Targeted Vaccine Boosting of TCR T-cell Therapy Enhances Antitumor Function and Eradicates Solid Tumors

T-cell receptor (TCR)-modified T-cell therapies have shown promise against solid tumors, but overall therapeutic benefits have been modest due in part to suboptimal T-cell persistence and activation in vivo, alongside potential tumor antigen escape. In this study, we demonstrate an approach to enhance the in vivo persistence and function of TCR T cells through combination with Amphiphile (AMP) vaccination including cognate TCR T peptides. AMP modification improves lymph node targeting of conjugated tumor immunogens and adjuvants, thereby coordinating a robust T cell-activating endogenous immune response. AMP vaccine combination with TCR T-cell therapy led to complete eradication and durable responses against established murine solid tumors refractory to TCR T-cell monotherapy. Enhanced antitumor efficacy was correlated with simultaneous in vivo invigoration of adoptively transferred TCR T cells and in situ expansion of the endogenous antitumor T-cell repertoire. Long-term protection against tumor recurrence in AMP-vaccinated mice was associated with antigen spreading to additional tumor-associated antigens not targeted by vaccination. AMP vaccination further correlated with pro-inflammatory lymph node transcriptional reprogramming and increased antigen presenting-cell maturation, resulting in TCR T-cell expansion and functional enhancement in lymph nodes and solid tumor parenchyma without lymphodepletion. In vitro evaluation of AMP peptides with matched human TCR T cells targeting NY-ESO-1, mutant KRAS, and HPV16 E7 illustrated the clinical potential of AMP vaccination to enhance human TCR T-cell proliferation, activation, and antitumor activity. Taken together, these studies provide rationale and evidence to support clinical evaluation of combining AMP vaccination with TCR T-cell therapies to augment antitumor activity.

Breaking NGF-TrkA immunosuppression in melanoma sensitizes immunotherapy for durable memory T cell protection

Melanoma cells, deriving from neuroectodermal melanocytes, may exploit the nervous system's immune privilege for growth. Here we show that nerve growth factor (NGF) has both melanoma cell intrinsic and extrinsic immunosuppressive functions. Autocrine NGF engages tropomyosin receptor kinase A (TrkA) on melanoma cells to desensitize interferon γ signaling, leading to T and natural killer cell exclusion. In effector T cells that upregulate surface TrkA expression upon T cell receptor activation, paracrine NGF dampens T cell receptor signaling and effector function. Inhibiting NGF, either through genetic modification or with the tropomyosin receptor kinase inhibitor larotrectinib, renders melanomas susceptible to immune checkpoint blockade therapy and fosters long-term immunity by activating memory T cells with low affinity. These results identify the NGF-TrkA axis as an important suppressor of anti-tumor immunity and suggest larotrectinib might be repurposed for immune sensitization. Moreover, by enlisting low-affinity T cells, anti-NGF reduces acquired resistance to immune checkpoint blockade and prevents melanoma recurrence.

Lymph-node-targeted, mKRAS-specific amphiphile vaccine in pancreatic and colorectal cancer: the phase 1 AMPLIFY-201 trial

Pancreatic and colorectal cancers are often KRAS mutated and are incurable when tumor DNA or protein persists or recurs after curative intent therapy. Cancer vaccine ELI-002 2P enhances lymph node delivery and immune response using amphiphile (Amph) modification of G12D and G12R mutant KRAS (mKRAS) peptides (Amph-Peptides-2P) together with CpG oligonucleotide adjuvant (Amph-CpG-7909). We treated 25 patients (20 pancreatic and five colorectal) who were positive for minimal residual mKRAS disease (ctDNA and/or serum tumor antigen) after locoregional treatment in a phase 1 study of fixed-dose Amph-Peptides-2P and ascending-dose Amph-CpG-7909; study enrollment is complete with patient follow-up ongoing. Primary endpoints included safety and recommended phase 2 dose (RP2D). The secondary endpoint was tumor biomarker response (longitudinal ctDNA or tumor antigen), with exploratory endpoints including immunogenicity and relapse-free survival (RFS). No dose-limiting toxicities were observed, and the RP2D was 10.0 mg of Amph-CpG-7909. Direct ex vivo mKRAS-specific T cell responses were observed in 21 of 25 patients (84%; 59% both CD4+ and CD8+); tumor biomarker responses were observed in 21 of 25 patients (84%); biomarker clearance was observed in six of 25 patients (24%; three pancreatic and three colorectal); and the median RFS was 16.33 months. Efficacy correlated with T cell responses above or below the median fold increase over baseline (12.75-fold): median tumor biomarker reduction was -76.0% versus -10.2% (P < 0.0014), and the median RFS was not reached versus 4.01 months (hazard ratio = 0.14; P = 0.0167). ELI-002 2P was safe and induced considerable T cell responses in patients with immunotherapy-recalcitrant KRAS-mutated tumors. ClinicalTrials.gov identifier: NCT04853017 .

Adaptive immune cells are necessary for SARS-CoV-2-induced pathology

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is causing the ongoing global pandemic associated with morbidity and mortality in humans. Although disease severity correlates with immune dysregulation, the cellular mechanisms of inflammation and pathogenesis of COVID-19 remain relatively poorly understood. Here, we used mouse-adapted SARS-CoV-2 strain MA10 to investigate the role of adaptive immune cells in disease. We found that while infected wild-type mice lost ~10% weight by 3 to 4 days postinfection, rag-/- mice lacking B and T lymphocytes did not lose weight. Infected lungs at peak weight loss revealed lower pathology scores, fewer neutrophils, and lower interleukin-6 and tumor necrosis factor-α in rag-/- mice. Mice lacking αβ T cells also had less severe weight loss, but adoptive transfer of T and B cells into rag-/- mice did not significantly change the response. Collectively, these findings suggest that while adaptive immune cells are important for clearing SARS-CoV-2 infection, this comes at the expense of increased inflammation and pathology.

Single-cell deconvolution reveals high lineage- and location-dependent heterogeneity in mesenchymal multivisceral stage 4 colorectal cancer

Metastasized colorectal cancer (CRC) is associated with a poor prognosis and rapid disease progression. Besides hepatic metastasis, peritoneal carcinomatosis is the major cause of death in Union for International Cancer Control (UICC) stage IV CRC patients. Insights into differential site-specific reconstitution of tumor cells and the corresponding tumor microenvironment are still missing. Here, we analyzed the transcriptome of single cells derived from murine multivisceral CRC and delineated the intermetastatic cellular heterogeneity regarding tumor epithelium, stroma, and immune cells. Interestingly, we found an intercellular site-specific network of cancer-associated fibroblasts and tumor epithelium during peritoneal metastasis as well as an autologous feed-forward loop in cancer stem cells. We furthermore deciphered a metastatic dysfunctional adaptive immunity by a loss of B cell-dependent antigen presentation and consecutive effector T cell exhaustion. Furthermore, we demonstrated major similarities of this murine metastatic CRC model with human disease and - based on the results of our analysis - provided an auspicious site-specific immunomodulatory treatment approach for stage IV CRC by intraperitoneal checkpoint inhibition.

Radiation dose, schedule, and novel systemic targets for radio-immunotherapy combinations

Immunotherapy combinations are being investigated to expand the benefit of immune checkpoint blockade across many cancer types. Radiation combinations, in particular using stereotactic body radiotherapy, are of keen interest because of underlying mechanistic rationale, safety, and availability as a standard of care in certain cancers. In addition to direct tumor cytotoxicity, radiation therapy has immunomodulatory effects such as induction of immunogenic cell death, enhancement of antigen presentation, and expansion of the T-cell receptor repertoire as well as recruitment and increased activity of tumor-specific effector CD8+ cells. Combinations of radiation with cytokines and/or chemokines and anti-programmed death 1 and anticytotoxic T-lymphocyte antigen 4 therapies have demonstrated safety and feasibility, as well as the potential to improve long-term outcomes and possibly induce out of irradiated field or abscopal responses. Novel immunoradiotherapy combinations represent a promising therapeutic approach to overcome radioresistance and further enhance systemic immunotherapy. Potential benefits include reversing CD8+ T-cell exhaustion, inhibiting myeloid-derived suppressor cells, and reversing M2 macrophage polarization as well as decreasing levels of colony-stimulating factor-1 and transforming growth factor-β. Here, we discuss current data and mechanistic rationale for combining novel immunotherapy agents with radiation therapy.

Coengineering specificity, safety, and function into T cells for cancer immunotherapy

Adoptive T-cell transfer (ACT) therapies, including of tumor infiltrating lymphocytes (TILs) and T cells gene-modified to express either a T cell receptor (TCR) or a chimeric antigen receptor (CAR), have demonstrated clinical efficacy for a proportion of patients and cancer-types. The field of ACT has been driven forward by the clinical success of CD19-CAR therapy against various advanced B-cell malignancies, including curative responses for some leukemia patients. However, relapse remains problematic, in particular for lymphoma. Moreover, for a variety of reasons, relative limited efficacy has been demonstrated for ACT of non-hematological solid tumors. Indeed, in addition to pre-infusion challenges including lymphocyte collection and manufacturing, ACT failure can be attributed to several biological processes post-transfer including, (i) inefficient tumor trafficking, infiltration, expansion and retention, (ii) chronic antigen exposure coupled with insufficient costimulation resulting in T-cell exhaustion, (iii) a range of barriers in the tumor microenvironment (TME) mediated by both tumor cells and suppressive immune infiltrate, (iv) tumor antigen heterogeneity and loss, or down-regulation of antigen presentation machinery, (v) gain of tumor intrinsic mechanisms of resistance such as to apoptosis, and (vi) various forms of toxicity and other adverse events in patients. Affinity-optimized TCRs can improve T-cell function and innovative CAR designs as well as gene-modification strategies can be used to coengineer specificity, safety, and function into T cells. Coengineering strategies can be designed not only to directly support the transferred T cells, but also to block suppressive barriers in the TME and harness endogenous innate and adaptive immunity. Here, we review a selection of the remarkable T-cell coengineering strategies, including of tools, receptors, and gene-cargo, that have been developed in recent years to augment tumor control by ACT, more and more of which are advancing to the clinic.

Spatiotemporally programming cytokine immunotherapies through protein engineering

Cytokines have long been considered promising cancer immunotherapy agents due to their endogenous role in activating and proliferating lymphocytes. However, since the initial FDA approvals of Interleukin-2 (IL-2) and Interferon-ɑ (IFNɑ) for oncology over 30 years ago, cytokines have achieved little success in the clinic due to narrow therapeutic windows and dose-limiting toxicities. This is attributable to the discrepancy between the localized, regulated manner in which cytokines are deployed endogenously versus the systemic, untargeted administration used to date in most exogenous cytokine therapies. Furthermore, cytokines' ability to stimulate multiple cell types, often with paradoxical effects, may present significant challenges for their translation into effective therapies. Recently, protein engineering has emerged as a tool to address the shortcomings of first-generation cytokine therapies. In this perspective, we contextualize cytokine engineering strategies such as partial agonism, conditional activation and intratumoral retention through the lens of spatiotemporal regulation. By controlling the time, place, specificity, and duration of cytokine signaling, protein engineering can allow exogenous cytokine therapies to more closely approach their endogenous exposure profile, ultimately moving us closer to unlocking their full therapeutic potential.

Biodegradable scaffolds for enhancing vaccine delivery

Sustained release of vaccine components is a potential method to boost efficacy compared with traditional bolus injection. Here, we show that a biodegradable hyaluronic acid (HA)-scaffold, termed HA cryogel, mediates sustained antigen and adjuvant release in vivo leading to a durable immune response. Delivery from subcutaneously injected HA cryogels was assessed and a formulation which enhanced the immune response while minimizing the inflammation associated with the foreign body response was identified, termed CpG-OVA-HAC2. Dose escalation studies with CpG-OVA-HAC2 demonstrated that both the antibody and T cell responses were dose-dependent and influenced by the competency of neutrophils to perform oxidative burst. In immunodeficient post-hematopoietic stem cell transplanted mice, immunization with CpG-OVA-HAC2 elicited a strong antibody response, three orders of magnitude higher than dose-matched bolus injection. In a melanoma model, CpG-OVA-HAC2 induced dose-responsive prophylactic protection, slowing the tumor growth rate and enhancing overall survival. Upon rechallenge, none of the mice developed new tumors suggesting the development of robust immunological memory and long-lasting protection against repeat infections. CpG-OVA-HAC2 also enhanced survival in mice with established tumors. The results from this work support the potential for CpG-OVA-HAC2 to enhance vaccine delivery.

HDACi-dependent Microenvironmental Normalization Overcomes Tumor Burden-induced T-cell Exhaustion

PURPOSE

T-cell exhaustion limits immunotherapy for the treatment of solid tumors. Although immune checkpoint blockade and adoptive T-cell therapy (ACT) can mediate tumor regression, their potency is often determined by tumor burden. Here, we identified tumor burden-related pathway changes that are conducive to T-cell exhaustion. We then determined whether microenvironmental reprogramming via epigenetic modulation could reverse T-cell exhaustion and improve immunotherapeutic responsiveness.

EXPERIMENTAL DESIGN

We developed a murine syngeneic tumor model wherein an increased burden ablated therapeutic responsiveness to ACT, which corresponded with systemic induction of T-cell exhaustion. Transcriptome analysis of these large tumors allowed us to characterize changes to immunosuppressive pathway expression during class I histone deacetylase inhibitor MS-275 treatment. We then measured the therapeutic impact of MS-275 during ACT and assessed T-cell exhaustion by transcriptome/phenotypic analysis.

RESULTS

ACT durably regressed small tumors but failed to control large tumors, which were associated with systemic T-cell exhaustion and ablation of T-cell responses. Large tumors were defined by an immunosuppressive pathway signature. MS-275 reversed this pathway signature and promoted durable regression of large tumors during ACT. Prototypical exhaustion marker Tim-3 was selectively upregulated in transferred T cells despite displaying a reduced exhaustion signature. Instead, we observed enhanced activation-dependent signaling correlating with enrichment of the IL2-STAT5 signaling axis. Activated CD8+ T-cell responses were predominantly skewed toward terminal effector cell-like CD44+ Tim-3hi TCF1- CD127- KLRG1+ differentiation.

CONCLUSIONS

Tumor burden-induced pathway changes can be reversed through epigenetic reprogramming, enabling the conversion from T-cell exhaustion to effector lineage differentiation.

Evaluation of CD47 in the Suppressive Tumor Microenvironment and Immunotherapy in Prostate Cancer

Background

CD47 has high levels of expression in malignant cancer cells, which binds to SIRP-α to release the "don't eat me" signal and prevents mononuclear macrophages from phagocytosing the cells. Resistance to drugs and metastases are potential barriers for prostate cancer endocrine therapy. Although immunotherapy for tumors has developed rapidly in the last few decades, its effectiveness in treating prostate cancer is unsatisfactory. Prostate cancer has a high-expression level of CD47. Therefore, a novel approach for potential immunotherapy may be provided by investigating the relationship among CD47 and the infiltration of immune cells in the prostate carcinoma.

Methods

The GEPIA database was utilized to compare the abundance of CD47 in malignant tissues with tissues that were normal. Furthermore, the function of CD47 in prostate carcinoma was assessed by CancerSEA. The association among CD47 and the tumor microenvironment was assessed utilizing the TISCH single cell data database. By using TIMER, the connection among CD47 and immunological invasion of prostate cancer was explored. Moreover, macrophages were cocultured with mouse prostate cancer cell RM-1 blocked by CD47 antibody to observe the changes in phagocytosis efficiency in vitro.

Results

Expression level of CD47 is upregulated in prostate carcinoma, and it is closely connected with prostate cancer's inadequate immune invasion. CD47 antibody blocking promotes macrophage phagocytosis of RM-1.

Conclusion

Our research demonstrates a closely relationship among CD47 and the immunological microenvironment of prostate cancer, and blocking CD47 can promote macrophages to phagocytosis of prostate cancer cells. Therefore, CD47 may provide novel strategies for potential immunotherapy of prostate cancer.

PD-L1/PD-1 checkpoint pathway regulates hippocampal neuronal excitability and learning and memory behavior

Programmed death protein 1 (PD-1) and its ligand PD-L1 constitute an immune checkpoint pathway. We report that neuronal PD-1 signaling regulates learning/memory in health and disease. Mice lacking PD-1 (encoded by Pdcd1) exhibit enhanced long-term potentiation (LTP) and memory. Intraventricular administration of anti-mouse PD-1 monoclonal antibody (RMP1-14) potentiated learning and memory. Selective deletion of PD-1 in excitatory neurons (but not microglia) also enhances LTP and memory. Traumatic brain injury (TBI) impairs learning and memory, which is rescued by Pdcd1 deletion or intraventricular PD-1 blockade. Conversely, re-expression of Pdcd1 in PD-1-deficient hippocampal neurons suppresses memory and LTP. Exogenous PD-L1 suppresses learning/memory in mice and the excitability of mouse and NHP hippocampal neurons through PD-1. Notably, neuronal activation suppresses PD-L1 secretion, and PD-L1/PD-1 signaling is distinctly regulated by learning and TBI. Thus, conditions that reduce PD-L1 levels or PD-1 signaling could promote memory in both physiological and pathological conditions.

Rescue of dendritic cells from glycolysis inhibition improves cancer immunotherapy in mice

Inhibition of glycolysis in immune cells and cancer cells diminishes their activity, and thus combining immunotherapies with glycolytic inhibitors is challenging. Herein, a strategy is presented where glycolysis is inhibited in cancer cells using PFK15 (inhibitor of PFKFB3, rate-limiting step in glycolysis), while simultaneously glycolysis and function is rescued in DCs by delivery of fructose-1,6-biphosphate (F16BP, one-step downstream of PFKFB3). To demonstrate the feasibility of this strategy, vaccine formulations are generated using calcium-phosphate chemistry, that incorporate F16BP, poly(IC) as adjuvant, and phosphorylated-TRP2 peptide antigen and tested in challenging and established YUMM1.1 tumours in immunocompetent female mice. Furthermore, to test the versatility of this strategy, adoptive DC therapy is developed with formulations that incorporate F16BP, poly(IC) as adjuvant and mRNA derived from B16F10 cells as antigens in established B16F10 tumours in immunocompetent female mice. F16BP vaccine formulations rescue DCs in vitro and in vivo, significantly improve the survival of mice, and generate cytotoxic T cell (Tc) responses by elevating Tc1 and Tc17 cells within the tumour. Overall, these results demonstrate that rescuing glycolysis of DCs using metabolite-based formulations can be utilized to generate immunotherapy even in the presence of glycolytic inhibitor.

Cooperative phagocytosis of solid tumours by macrophages triggers durable anti-tumour responses

In solid tumours, the abundance of macrophages is typically associated with a poor prognosis. However, macrophage clusters in tumour-cell nests have been associated with survival in some tumour types. Here, by using tumour organoids comprising macrophages and cancer cells opsonized via a monoclonal antibody, we show that highly ordered clusters of macrophages cooperatively phagocytose cancer cells to suppress tumour growth. In mice with poorly immunogenic tumours, the systemic delivery of macrophages with signal-regulatory protein alpha (SIRPα) genetically knocked out or else with blockade of the CD47-SIRPα macrophage checkpoint was combined with the monoclonal antibody and subsequently triggered the production of endogenous tumour-opsonizing immunoglobulin G, substantially increased the survival of the animals and helped confer durable protection from tumour re-challenge and metastasis. Maximizing phagocytic potency by increasing macrophage numbers, by tumour-cell opsonization and by disrupting the phagocytic checkpoint CD47-SIRPα may lead to durable anti-tumour responses in solid cancers.

STING Protein-Based In Situ Vaccine Synergizes CD4+ T, CD8+ T, and NK Cells for Tumor Eradication

Stimulator of interferon genes (STING) signaling is a promising target in cancer immunotherapy, with many ongoing clinical studies in combination with immune checkpoint blockade (ICB). Existing STING-based therapies largely focus on activating CD8+ T cell or NK cell-mediated cytotoxicity, while the role of CD4+ T cells in STING signaling has yet to be extensively studied in vivo. Here, a distinct CD4-mediated, protein-based combination therapy of STING and ICB as an in situ vaccine, is reported. The treatment eliminates subcutaneous MC38 and YUMM1.7 tumors in 70-100% of mice and protected all cured mice against rechallenge. Mechanistic studies reveal a robust TH 1 polarization and suppression of Treg of CD4+ T cells, followed by an effective collaboration of CD4+ T, CD8+ T, and NK cells to eliminate tumors. Finally, the potential to overcome host STING deficiency by significantly decreasing MC38 tumor burden in STING KO mice is demonstrated, addressing the translational challenge for the 19% of human population with loss-of-function STING variants.

Recent Advances in Antitumor Dendritic Cell Vaccines

Background: Dendritic cells (DCs) are the most important antigen-presenting cells in the body and play a key role in antigen recognition, uptake, processing, and presentation and mediate nonspecific immunity and specific immunity. Purpose: To summarize the main findings that DC vaccines are a new immunotherapy scheme combining the strengths of tumor antigens and DCs that can boost the body's identification and clearance of tumors. Methods: In this review, the authors focus on the biological characteristics of DCs, recent advances in the understanding of antitumor mechanisms, and the classification of DC vaccines. Results: The current progress of DC-based vaccine immunotherapy for common tumors with high morbidity or mortality in China were systematically summarize. Conclusions: The DC vaccines combining the strengths of tumor antigens will provide directions to explore reasonable, safe, and effective combination immunotherapy strategies for tumors in the future.

An iPSC-derived exosome-pulsed dendritic cell vaccine boosts antitumor immunity in melanoma

Induced pluripotent stem cells (iPSCs) express a broad spectrum of tumor-associated antigens and exert prophylactic effects on various tumors. However, some problems remain, such as potential tumorigenicity, challenges in transport to the lymph nodes and spleen, and limited antitumor effects. Thus, designing a safe and effective iPSC-based tumor vaccine is necessary. We prepared iPSC-derived exosomes and incubated them with DCs (dendritic cells) for pulsing to explore their antitumor effects in murine melanoma models. The antitumor immune response induced by the DC vaccine pulsed with iPSC exosomes (DC + EXO) was assessed in vitro and in vivo. After DC + EXO vaccination, extracted spleen T cells effectively killed a variety of tumor cells (melanoma, lung cancer, breast cancer, and colorectal cancer) in vitro. In addition, DC + EXO vaccination significantly inhibited melanoma growth and lung metastasis in mouse models. Furthermore, DC + EXO vaccination induced long-term T cell responses and prevented melanoma rechallenge. Finally, biocompatibility studies showed that the DC vaccine did not significantly alter the viability of normal cells and mouse viscera. Hence, our research may provide a prospective strategy of a safe and effective iPSC-based tumor vaccine for clinical use.

High-Dose Paclitaxel and its Combination with CSF1R Inhibitor in Polymeric Micelles for Chemoimmunotherapy of Triple Negative Breast Cancer

The presence of immunosuppressive immune cells in tumors is a significant barrier to the generation of therapeutic immune responses. Similarly, in vivo triple-negative breast cancer (TNBC) models often contain prevalent, immunosuppressive tumor-associated macrophages in the tumor microenvironment (TME), resulting in breast cancer initiation, invasion, and metastasis. Here, we test systemic chemoimmunotherapy using small-molecule agents, paclitaxel (PTX), and colony-stimulating factor 1 receptor (CSF1R) inhibitor, PLX3397, to enhance the adaptive T cell immunity against TNBCs in immunocompetent mouse TNBC models. We use high-capacity poly(2-oxazoline) (POx)-based polymeric micelles to greatly improve the solubility of insoluble PTX and PLX3397 and widen the therapeutic index of such drugs. The results demonstrate that high-dose PTX in POx, even as a single agent, exerts strong effects on TME and induces long-term immune memory. In addition, we demonstrate that the PTX and PLX3397 combination provides consistent therapeutic improvement across several TNBC models, resulting from the repolarization of the immunosuppressive TME and enhanced T cell immune response that suppress both the primary tumor growth and metastasis. Overall, the work emphasizes the benefit of drug reformulation and outlines potential translational path for both PTX and PTX with PLX3397 combination therapy using POx polymeric micelles for the treatment of TNBC.

Chemically programmed STING-activating nano-liposomal vesicles improve anticancer immunity

The often immune-suppressive tumor microenvironment (TME) may hinder immune evasion and response to checkpoint blockade therapies. Pharmacological activation of the STING pathway does create an immunologically hot TME, however, systemic delivery might lead to undesired off-target inflammatory responses. Here, we generate a small panel of esterase-activatable pro-drugs based on the structure of the non-nucleotide STING agonist MSA-2 that are subsequently stably incorporated into a liposomal vesicle for intravenous administration. The pharmacokinetic properties and immune stimulatory capacity of pro-drugs delivered via liposomes (SAProsomes) are enhanced compared to the free drug form. By performing efficacy screening among the SAProsomes incorporating different pro-drugs in syngeneic mouse tumor models, we find that superior therapeutic performance relies on improved delivery to the desired tumor and lymphoid compartments. The best candidate, SAProsome-3, highly stimulates secretion of inflammatory cytokines and creates a tumoricidal immune landscape. Notably, upon application to breast cancer or melanoma mouse models, SAProsome-3 elicits durable remission of established tumors and postsurgical tumor-free survival while decreasing metastatic burden without significant systemic toxicity. In summary, our work establishes the proof of principle for a better targeted and more efficient and safe STING agonist therapy.

Vaccine-boosted CAR T crosstalk with host immunity to reject tumors with antigen heterogeneity

Chimeric antigen receptor (CAR) T cell therapy effectively treats human cancer, but the loss of the antigen recognized by the CAR poses a major obstacle. We found that in vivo vaccine boosting of CAR T cells triggers the engagement of the endogenous immune system to circumvent antigen-negative tumor escape. Vaccine-boosted CAR T promoted dendritic cell (DC) recruitment to tumors, increased tumor antigen uptake by DCs, and elicited the priming of endogenous anti-tumor T cells. This process was accompanied by shifts in CAR T metabolism toward oxidative phosphorylation (OXPHOS) and was critically dependent on CAR-T-derived IFN-γ. Antigen spreading (AS) induced by vaccine-boosted CAR T enabled a proportion of complete responses even when the initial tumor was 50% CAR antigen negative, and heterogeneous tumor control was further enhanced by the genetic amplification of CAR T IFN-γ expression. Thus, CAR-T-cell-derived IFN-γ plays a critical role in promoting AS, and vaccine boosting provides a clinically translatable strategy to drive such responses against solid tumors.

Dual identity of tumor-associated macrophage in regulated cell death and oncotherapy

Tumor-associated macrophage (TAM) affects the intrinsic properties of tumor cells and the tumor microenvironment (TME), which can stimulate tumor cell proliferation, migration, and genetic instability, and macrophage diversity includes the diversity of tumors with different functional characteristics. Macrophages are now a central drug target in various diseases, especially in the TME, which, as "tumor promoters" and "immunosuppressors", have different responsibilities during tumor development and accompany by significant dynamic alterations in various subpopulations. Remodelling immunosuppression of TME and promotion of pre-existing antitumor immune responses is critical by altering TAM polarization, which is relevant to the efficacy of immunotherapy, and uncovering the exact mechanism of action of TAMs and identifying their specific targets is vital to optimizing current immunotherapies. Hence, this review aims to reveal the triadic interactions of macrophages with programmed death and oncotherapy, and to integrate certain relationships in cancer treatment.

Anti-tumor antibody isotype response can be modified with locally administered immunoadjuvants

In situ vaccination with immunostimulatory compounds is a demonstrated means to treat tumors preclinically. While these therapeutic effects have been attributed to the actions of T cells or innate immune activation, characterisation of the humoral immune response is seldom performed. This study aims to identify whether the injection of immunoadjuvants, Addavax (Adda) and cytosine-phosphorothioate-guanine oligodeoxynucleotide (CpG), intratumorally can influence the antibody response. Specifically, whether intratumoral injection of immunoadjuvants can alter the tumor-specific antibody target, titre and isotype. Following this, the study aimed to investigate whether serum obtained from in situ vaccinated mice could neutralise circulating tumor cells. Serum was obtained from mice bearing B16F10-OVA-Luc-GFP tumors treated with immunoadjuvants. Antibody targets' titre and isotype were assessed by indirect ELISA. The ability of serum to neutralise circulating cancer cells was evaluated in a B16F10 pseudo-metastatic model. It was observed that tumor-bearing mice mount a specific anti-tumor antibody response. Antibody titre and target were unaffected by in situ vaccination with immunoadjuvants; however, a higher amount of IgG2c was produced in mice receiving Adda plus CpG. Serum from in situ vaccinated mice was unable to neutralise circulating B16F10 cells. Thus, this study has demonstrated that anti-tumor antibody isotype may be modified using in situ vaccination; however, this alone is not sufficient to neutralise circulating cancer cells.

Autonomous IL-36R signaling in neutrophils activates potent antitumor effector functions

While the rapid advancement of immunotherapies has revolutionized cancer treatment, only a small fraction of patients derive clinical benefit. Eradication of large, established tumors appears to depend on engaging and activating both innate and adaptive immune system components to mount a rigorous and comprehensive immune response. Identifying such agents is a high unmet medical need, because they are sparse in the therapeutic landscape of cancer treatment. Here, we report that IL-36 cytokine can engage both innate and adaptive immunity to remodel an immune-suppressive tumor microenvironment (TME) and mediate potent antitumor immune responses via signaling in host hematopoietic cells. Mechanistically, IL-36 signaling modulates neutrophils in a cell-intrinsic manner to greatly enhance not only their ability to directly kill tumor cells but also promote T and NK cell responses. Thus, while poor prognostic outcomes are typically associated with neutrophil enrichment in the TME, our results highlight the pleiotropic effects of IL-36 and its therapeutic potential to modify tumor-infiltrating neutrophils into potent effector cells and engage both the innate and adaptive immune system to achieve durable antitumor responses in solid tumors.

Tumor-localized catalases can fail to alter tumor growth and transcriptional profiles in subcutaneous syngeneic mouse tumor models

Catalase is an antioxidant enzyme that catalyzes the rapid conversion of hydrogen peroxide to water and oxygen. Use of catalase as a cancer therapeutic has been proposed to reduce oxidative stress and hypoxia in the tumor microenvironment, both activities which are hypothesized to reduce tumor growth. Furthermore, exposing murine tumors to exogenous catalase was previously reported to have therapeutic benefit. We studied the therapeutic effect of tumor-localized catalases with the aim to further elucidate the mechanism of action. To do this, we engineered two approaches to maximize intratumoral catalase exposure: 1) an injected extracellular catalase with enhanced tumor retention, and 2) tumor cell lines that over-express intracellular catalase. Both approaches were characterized for functionality and tested for therapeutic efficacy and mechanism in 4T1 and CT26 murine syngeneic tumor models. The injected catalase was confirmed to have enzyme activity >30,000 U/mg and was retained at the injection site for more than one week in vivo. The engineered cell lines exhibited increased catalase activity and antioxidant capacity, with catalase over-expression that was maintained for at least one week after gene expression was induced in vivo. We did not observe a significant difference in tumor growth or survival between catalase-treated and untreated mice when either approach was used. Finally, bulk RNA sequencing of tumors was performed, comparing the gene expression of catalase-treated and untreated tumors. Gene expression analysis revealed very few differentially expressed genes as a result of exposure to catalase and notably, we did not observe changes consistent with an altered state of hypoxia or oxidative stress. In conclusion, we observe that sustained intratumoral catalase neither has therapeutic benefit nor triggers significant differential expression of genes associated with the anticipated therapeutic mechanism in the subcutaneous syngeneic tumor models used. Given the lack of effect observed, we propose that further development of catalase as a cancer therapeutic should take these findings into consideration.