Lipid Nanoparticle-mRNA Engineered Dendritic Cell Based Adoptive Cell Therapy Enhances Cancer Immune Response.

Lipid nanoparticles encapsulating mRNA (LNP-mRNA) revolutionized medicine over the past several years. While clinically approved indications currently focus on infectious disease vaccination, LNP-mRNA based treatments also hold promise for cancer immunotherapy. However, the route of dosing may impact treatment efficacy, safety, and dose. To minimize adverse effects, it is hypothesized that LNP-mRNA can be used to activate and engineer dendritic cells (DC) ex vivo before re-administration of these cells. Here, it is shown that LNP-mRNA engineered DCs can indeed vaccinate recipient mice. Vaccinated mice showed strong anti-tumor T cell responses, rejected tumor challenge, and displayed no evidence of toxicity. Further, it is found that DC specific ablation of the immune activating kinase NFkB inducing kinase (NIK) abrogated vaccination efficacy, demonstrating that adoptively transferred DCs can be functionally modified in addition to their antigen presentation capacity. Collectively, these studies show that ex vivo LNP-mRNA engineering of DCs is a feasible and robust therapeutic strategy for cancer.

The aged tumor microenvironment limits T cell control of cancer.

The etiology and effect of age-related immune dysfunction in cancer is not completely understood. Here we show that limited priming of CD8+ T cells in the aged tumor microenvironment (TME) outweighs cell-intrinsic defects in limiting tumor control. Increased tumor growth in aging is associated with reduced CD8+ T cell infiltration and function. Transfer of T cells from young mice does not restore tumor control in aged mice owing to rapid induction of T cell dysfunction. Cell-extrinsic signals in the aged TME drive a tumor-infiltrating age-associated dysfunctional (TTAD) cell state that is functionally, transcriptionally and epigenetically distinct from canonical T cell exhaustion. Altered natural killer cell-dendritic cell-CD8+ T cell cross-talk in aged tumors impairs T cell priming by conventional type 1 dendritic cells and promotes TTAD cell formation. Aged mice are thereby unable to benefit from therapeutic tumor vaccination. Critically, myeloid-targeted therapy to reinvigorate conventional type 1 dendritic cells can improve tumor control and restore CD8+ T cell immunity in aging.

A non-lipid nucleic acid delivery vector with dendritic cell tropism and stimulation.

Rationale: Nucleic acid constructs are commonly used for vaccination, immune stimulation, and gene therapy, but their use in cancer still remains limited. One of the reasons is that systemic delivery to tumor-associated antigen-presenting cells (dendritic cells and macrophages) is often inefficient, while off-target nucleic acid-sensing immune pathways can stimulate systemic immune responses. Conversely, certain carbohydrate nanoparticles with small molecule payloads have been shown to target these cells efficiently in the tumor microenvironment. Yet, nucleic acid incorporation into such carbohydrate-based nanoparticles has proven challenging. Methods: We developed a novel approach using cross-linked bis succinyl-cyclodextrin (b-s-CD) nanoparticles to efficiently deliver nucleic acids and small-molecule immune enhancer to phagocytic cells in tumor environments and lymph nodes. Our study involved incorporating these components into the nanoparticles and assessing their efficacy in activating antigen-presenting cells. Results: The multi-modality immune stimulators effectively activated antigen-presenting cells and promoted anti-tumor immunity in vivo. This was evidenced by enhanced delivery to phagocytic cells and subsequent immune response activation in tumor environments and lymph nodes. Conclusion: Here, we describe a new approach to incorporating both nucleic acids and small-molecule immune enhancers into cross-linked bis succinyl-cyclodextrin (b-s-CD) nanoparticles for efficient delivery to phagocytic cells in tumor environments and lymph nodes in vivo. These multi-modality immune stimulators can activate antigen-presenting cells and foster anti-tumor immunity. We argue that this strategy can potentially be used to enhance anti-tumor efficacy.

Host-functionalization of macrin nanoparticles to enable drug loading and control tumor-associated macrophage phenotype.

Macrophages are critical regulators of the tumor microenvironment and often present an immuno-suppressive phenotype, supporting tumor growth and immune evasion. Promoting a robust pro-inflammatory macrophage phenotype has emerged as a therapeutic modality that supports tumor clearance, including through synergy with immune checkpoint therapies. Polyglucose nanoparticles (macrins), which possess high macrophage affinity, are useful vehicles for delivering drugs to macrophages, potentially altering their phenotype. Here, we examine the potential of functionalized macrins, synthesized by crosslinking carboxymethyl dextran with L-lysine, as effective carriers of immuno-stimulatory drugs to tumor-associated macrophages (TAMs). Azide groups incorporated during particle synthesis provided a handle for click-coupling of propargyl-modified ß-cyclodextrin to macrins under mild conditions. Fluorescence-based competitive binding assays revealed the ability of ß-cyclodextrin to non-covalently bind to hydrophobic immuno-stimulatory drug candidates (Keq ~ 103 M-1), enabling drug loading within nanoparticles. Furthermore, transcriptional profiles of macrophages indicated robust pro-inflammatory reprogramming (elevated Nos2 and Il12; suppressed Arg1 and Mrc1 expression levels) for a subset of these immuno-stimulatory agents (UNC2025 and R848). Loading of R848 into the modified macrins improved the drug's effect on primary murine macrophages by three-fold in vitro. Intravital microscopy in IL-12-eYFP reporter mice (24 h post-injection) revealed a two-fold enhancement in mean YFP fluorescence intensity in macrophages targeted with R848-loaded macrins, relative to vehicle controls, validating the desired pro-inflammatory reprogramming of TAMs in vivo by cell-targeted drug delivery. Finally, in an intradermal MC38 tumor model, cyclodextrin-modified macrin NPs loaded with immunostimulatory drugs significantly reduced tumor growth. Therefore, efficient and effective repolarization of tumor-associated macrophages to an M1-like phenotype-via drug-loaded macrins-inhibits tumor growth and may be useful as an adjuvant to existing immune checkpoint therapies.

Pharmacological Polarization of Tumor-Associated Macrophages Toward a CXCL9 Antitumor Phenotype.

Tumor-associated macrophages (TAM) are a diverse population of myeloid cells that are often abundant and immunosuppressive in human cancers. CXCL9Hi TAM has recently been described to have an antitumor phenotype and is linked to immune checkpoint response. Despite the emerging understanding of the unique antitumor TAM phenotype, there is a lack of TAM-specific therapeutics to exploit this new biological understanding. Here, the discovery and characterization of multiple small-molecule enhancers of chemokine ligand 9 (CXCL9) and their targeted delivery in a TAM-avid systemic nanoformulation is reported. With this strategy, it is efficient encapsulation and release of multiple drug loads that can efficiently induce CXCL9 expression in macrophages, both in vitro and in vivo in a mouse tumor model. These observations provide a window into the molecular features that define TAM-specific states, an insight a novel therapeutic anticancer approach is used to discover.

Highly Active Myeloid Therapy for Cancer.

Tumor-associated macrophages (TAM) interact with cancer and stromal cells and are integral to sustaining many cancer-promoting features. Therapeutic manipulation of TAM could therefore improve clinical outcomes and synergize with immunotherapy and other cancer therapies. While different nanocarriers have been used to target TAM, a knowledge gap exists on which TAM pathways to target and what payloads to deliver for optimal antitumor effects. We hypothesized that a multipart combination involving the Janus tyrosine kinase (JAK), noncanonical nuclear factor kappa light chain enhancer of activated B cells (NF-κB), and toll-like receptor (TLR) pathways could lead to a highly active myeloid therapy (HAMT). Thus, we devised a screen to determine drug combinations that yield maximum IL-12 production from myeloid cells to treat the otherwise highly immunosuppressive myeloid environments in tumors. Here we show the extraordinary efficacy of a triple small-molecule combination in a TAM-targeted nanoparticle for eradicating murine tumors, jumpstarting a highly efficient antitumor response by adopting a distinctive antitumor TAM phenotype and synergizing with other immunotherapies. The HAMT therapy represents a recently developed approach in immunotherapy and leads to durable responses in murine cancer models.

Hybrid LNP Prime Dendritic Cells for Nucleotide Delivery.

The efficient activation of professional antigen-presenting cells-such as dendritic cells (DC)-in tumors and lymph nodes is critical for the design of next-generation cancer vaccines and may be able to provide anti-tumor effects by itself through immune stimulation. The challenge is to stimulate these cells without causing excessive toxicity. It is hypothesized that a multi-pronged combinatorial approach to DC stimulation would allow dose reductions of innate immune receptor-stimulating TLR3 agonists while enhancing drug efficacy. Here, a hybrid lipid nanoparticle (LNP) platform is developed and tested for double-stranded RNA (polyinosinic:polycytidylic acid for TLR3 agonism) and immune modulator (L-CANDI) delivery. This study shows that the ≈120 nm hybrid nanoparticles-in-nanoparticles effectively eradicate tumors by themselves and generate long-lasting, durable anti-tumor immunity in mouse models.

Dendritic cells as shepherds of T cell immunity in cancer.

In cancer patients, dendritic cells (DCs) in tumor-draining lymph nodes can present antigens to naive T cells in ways that break immunological tolerance. The clonally expanded progeny of primed T cells are further regulated by DCs at tumor sites. Intratumoral DCs can both provide survival signals to and drive effector differentiation of incoming T cells, thereby locally enhancing antitumor immunity; however, the paucity of intratumoral DCs or their expression of immunoregulatory molecules often limits antitumor T cell responses. Here, we review the current understanding of DC-T cell interactions at both priming and effector sites of immune responses. We place emerging insights into DC functions in tumor immunity in the context of DC development, ontogeny, and functions in other settings and propose that DCs control at least two T cell-associated checkpoints of the cancer immunity cycle. Our understanding of both checkpoints has implications for the development of new approaches to cancer immunotherapy.

Non-cell-autonomous cancer progression from chromosomal instability.

Chromosomal instability (CIN) is a driver of cancer metastasis1-4, yet the extent to which this effect depends on the immune system remains unknown. Using ContactTracing-a newly developed, validated and benchmarked tool to infer the nature and conditional dependence of cell-cell interactions from single-cell transcriptomic data-we show that CIN-induced chronic activation of the cGAS-STING pathway promotes downstream signal re-wiring in cancer cells, leading to a pro-metastatic tumour microenvironment. This re-wiring is manifested by type I interferon tachyphylaxis selectively downstream of STING and a corresponding increase in cancer cell-derived endoplasmic reticulum (ER) stress response. Reversal of CIN, depletion of cancer cell STING or inhibition of ER stress response signalling abrogates CIN-dependent effects on the tumour microenvironment and suppresses metastasis in immune competent, but not severely immune compromised, settings. Treatment with STING inhibitors reduces CIN-driven metastasis in melanoma, breast and colorectal cancers in a manner dependent on tumour cell-intrinsic STING. Finally, we show that CIN and pervasive cGAS activation in micronuclei are associated with ER stress signalling, immune suppression and metastasis in human triple-negative breast cancer, highlighting a viable strategy to identify and therapeutically intervene in tumours spurred by CIN-induced inflammation.

A neutrophil response linked to tumor control in immunotherapy.

Neutrophils accumulate in solid tumors, and their abundance correlates with poor prognosis. Neutrophils are not homogeneous, however, and could play different roles in cancer therapy. Here, we investigate the role of neutrophils in immunotherapy, leading to tumor control. We show that successful therapies acutely expanded tumor neutrophil numbers. This expansion could be attributed to a Sellhi state rather than to other neutrophils that accelerate tumor progression. Therapy-elicited neutrophils acquired an interferon gene signature, also seen in human patients, and appeared essential for successful therapy, as loss of the interferon-responsive transcription factor IRF1 in neutrophils led to failure of immunotherapy. The neutrophil response depended on key components of anti-tumor immunity, including BATF3-dependent DCs, IL-12, and IFNγ. In addition, we found that a therapy-elicited systemic neutrophil response positively correlated with disease outcome in lung cancer patients. Thus, we establish a crucial role of a neutrophil state in mediating effective cancer therapy.

Dual Immunostimulatory Pathway Agonism through a Synthetic Nanocarrier Triggers Robust Anti-Tumor Immunity in Murine Glioblastoma.

Myeloid cells are abundant, create a highly immunosuppressive environment in glioblastoma (GBM), and thus contribute to poor immunotherapy responses. Based on the hypothesis that small molecules can be used to stimulate myeloid cells to elicit anti-tumor effector functions, a synthetic nanoparticle approach is developed to deliver dual NF-kB pathway-inducing agents into these cells via systemic administration. Synthetic, cyclodextrin-adjuvant nanoconstructs (CANDI) with high affinity for tumor-associated myeloid cells are dually loaded with a TLR7 and 8 (Toll-like receptor, 7 and 8) agonist (R848) and a cIAP (cellular inhibitor of apoptosis protein) inhibitor (LCL-161) to dually activate these myeloid cells. Here CANDI is shown to: i) readily enter the GBM tumor microenvironment (TME) and accumulate at high concentrations, ii) is taken up by tumor-associated myeloid cells, iii) potently synergize payloads compared to monotherapy, iv) activate myeloid cells, v) fosters a "hot" TME with high levels of T effector cells, and vi) controls the growth of murine GBM as mono- and combination therapies with anti-PD1. Multi-pathway targeted myeloid stimulation via the CANDI platform can efficiently drive anti-tumor immunity in GBM.

Resident Kupffer cells and neutrophils drive liver toxicity in cancer immunotherapy.

Immunotherapy is revolutionizing cancer treatment but is often restricted by toxicities. What distinguishes adverse events from concomitant antitumor reactions is poorly understood. Here, using anti-CD40 treatment in mice as a model of TH1-promoting immunotherapy, we showed that liver macrophages promoted local immune-related adverse events. Mechanistically, tissue-resident Kupffer cells mediated liver toxicity by sensing lymphocyte-derived IFN-γ and subsequently producing IL-12. Conversely, dendritic cells were dispensable for toxicity but drove tumor control. IL-12 and IFN-γ were not toxic themselves but prompted a neutrophil response that determined the severity of tissue damage. We observed activation of similar inflammatory pathways after anti-PD-1 and anti-CTLA-4 immunotherapies in mice and humans. These findings implicated macrophages and neutrophils as mediators and effectors of aberrant inflammation in TH1-promoting immunotherapy, suggesting distinct mechanisms of toxicity and antitumor immunity.

Dendritic cell targeting with Fc-enhanced CD40 antibody agonists induces durable antitumor immunity in humanized mouse models of bladder cancer.

Intravesical immunotherapy using Bacille Calmette-Guérin (BCG) attenuated bacteria delivered transurethrally to the bladder has been the standard of care for patients with high-risk non-muscle-invasive bladder cancer (NMIBC) for several decades. BCG therapy continues to be limited by high rates of disease recurrence and progression, and patients with BCG-unresponsive disease have few effective salvage therapy options besides radical cystectomy, highlighting a need for new therapies. We report that the immune-stimulatory receptor CD40 is highly expressed on dendritic cells (DCs) within the bladder tumor microenvironment of orthotopic bladder cancer mouse models, recapitulating CD40 expression by DCs found in human disease. We demonstrate that local CD40 agonism in mice with orthotopic bladder cancer through intravesical delivery of anti-CD40 agonist antibodies drives potent antitumor immunity and induces pharmacodynamic effects in the bladder tumor microenvironment, including a reduction in CD8+ T cells with an exhausted phenotype. We further show that type 1 conventional DCs (cDC1) and CD8+ T cells are required for both bladder cancer immune surveillance and anti-CD40 agonist antibody responses. Using orthotopic murine models humanized for CD40 and Fcγ receptors, we demonstrate that intravesical treatment with a fully human, Fc-enhanced anti-CD40 agonist antibody (2141-V11) induces robust antitumor activity in both treatment-naïve and treatment-refractory settings, driving long-term systemic antitumor immunity with no evidence of systemic toxicity. These findings support targeting CD40-expressing DCs in the bladder cancer microenvironment through an intravesical agonistic antibody approach for the treatment of NMIBC.

Cancer metastasis as a non-healing wound.

Most cancer deaths are caused by metastasis: recurrence of disease by disseminated tumour cells at sites distant from the primary tumour. Large numbers of disseminated tumour cells are released from the primary tumour, even during the early stages of tumour growth. However, only a minority survive as potential seeds for future metastatic outgrowths. These cells must adapt to a relatively inhospitable microenvironment, evade immune surveillance and progress from the micro- to macro-metastatic stage to generate a secondary tumour. A pervasive driver of this transition is chronic inflammatory signalling emanating from tumour cells themselves. These signals can promote migration and engagement of stem and progenitor cell function, events that are also central to a wound healing response. In this review, we revisit the concept of cancer as a non-healing wound, first introduced by Virchow in the 19th century, with a new tumour cell-intrinsic perspective on inflammation and focus on metastasis. Cellular responses to inflammation in both wound healing and metastasis are tightly regulated by crosstalk with the surrounding microenvironment. Targeting or restoring canonical responses to inflammation could represent a novel strategy to prevent the lethal spread of cancer.

Phase II Trial of IL-12 Plasmid Transfection and PD-1 Blockade in Immunologically Quiescent Melanoma.

PURPOSE: Tumors with low frequencies of checkpoint positive tumor-infiltrating lymphocytes (cpTIL) have a low likelihood of response to PD-1 blockade. We conducted a prospective multicenter phase II trial of intratumoral plasmid IL-12 (tavokinogene telseplasmid; "tavo") electroporation combined with pembrolizumab in patients with advanced melanoma with low frequencies of checkpoint positive cytotoxic lymphocytes (cpCTL). PATIENTS AND METHODS: Tavo was administered intratumorally days 1, 5, and 8 every 6 weeks while pembrolizumab (200 mg, i.v.) was administered every 3 weeks. The primary endpoint was objective response rate (ORR) by RECIST, secondary endpoints included duration of response, overall survival and progression-free survival. Toxicity was evaluated by the CTCAE v4. Extensive correlative analysis was done. RESULTS: The combination of tavo and pembrolizumab was well tolerated with adverse events similar to those previously reported with pembrolizumab alone. Patients had a 41% ORR (n = 22, RECIST 1.1) with 36% complete responses. Correlative analysis showed that the combination enhanced immune infiltration and sustained the IL-12/IFNγ feed-forward cycle, driving intratumoral cross-presenting dendritic cell subsets with increased TILs, emerging T cell receptor clones and, ultimately, systemic cellular immune responses. CONCLUSIONS: The combination of tavo and pembrolizumab was associated with a higher than expected response rate in this poorly immunogenic population. No new or unexpected toxicities were observed. Correlative analysis showed T cell infiltration with enhanced immunity paralleling the clinical activity in low cpCTL tumors.

Dendritic Cells, the T-cell-inflamed Tumor Microenvironment, and Immunotherapy Treatment Response.

The development of the most successful cancer immunotherapies in solid tumors, immune-checkpoint blockade, has focused on factors regulating T-cell activation. Until recently, the field has maintained a predominately T-cell centric view of immunotherapy, leaving aside the impact of innate immunity and especially myeloid cells. Dendritic cells (DC) are dominant partners of T cells, necessary for initiation of adaptive immune responses. Emerging evidence supports a broader role for DCs in tumors including the maintenance and support of effector functions during T-cell responses. This relationship is evidenced by the association of activated DCs with immune-checkpoint blockade responses and transcriptional analysis of responding tumors demonstrating the presence of type I IFN transcripts and DC relevant chemokines. T-cell-inflamed tumors preferentially respond to immunotherapies compared with non-T-cell-inflamed tumors and this model suggests a potentially modifiable spectrum of tumor microenvironmental immunity. Although host and commensal factors may limit the T-cell-inflamed phenotype, tumor cell intrinsic factors are gaining prominence as therapeutic targets. For example, tumor WNT/ß-catenin signaling inhibits production of chemokine gradients and blocking DC recruitment to tumors. Conversely, mechanisms of innate immune nucleic acid sensing, normally operative during pathogen response, may enhance DC accumulation and make tumors more susceptible to cancer immunotherapy. Elucidating mechanisms whereby DCs infiltrate and become activated within tumors may provide new opportunities for therapeutic intervention. Conceptually, this would facilitate conversion of non-T-cell-inflamed to T-cell-inflamed states or overcome secondary resistance mechanisms in T-cell-inflamed tumors, expanding the proportion of patients who benefit from cancer immunotherapy.

LTX-315 sequentially promotes lymphocyte-independent and lymphocyte-dependent antitumor effects.

LTX-315 is an oncolytic peptide that has antitumor efficacy in mice grafted with various tumor cell lines and is currently being tested in phase II clinical trials. Here we aimed to further evaluate LTX-315 in conditional genetic mouse models of cancer that typically resist current treatment options and to better understand the drug's mode of action in vivo. We report LTX-315 mediates profound antitumor effects against Braf- and Pten-driven melanoma and delays the progression of Kras- and P53-driven soft tissue sarcoma in mice. Additionally, we show in melanoma that LTX-315 triggers two sequential phases of antitumor response. The first phase of response, which begins within minutes of drug delivery into tumors, is defined by disrupted tumor vasculature and decreased tumor burden and occurs independently of lymphocytes. The second phase of response, which continues over weeks, is defined by long-term alteration of the tumor microenvironment; the changes induced by LTX-315 are most notably characterized by CD8+ T cell infiltration. We further show that these CD8+ T cells are involved in suppressing melanoma outgrowth in mice and report similar CD8+ T cell infiltration following LTX-315 treatment in melanoma and sarcoma patients. Taken together, these findings reveal LTX-315's multiple antitumor effects, including disrupting the tumor vasculature and promoting the conversion of poorly immunogenic tumors into ones that display antitumor T cell immunity.

Development of Adamantane-Conjugated TLR7/8 Agonists for Supramolecular Delivery and Cancer Immunotherapy.

Tumor-associated macrophages (TAMs) are often abundant in solid cancers, assuming an immunosuppressive (M2-like) phenotype which supports tumor growth and immune escape. Recent methods have focused on identification of means (e.g., drugs, nanomaterials) that polarize TAMs to a tumor suppressive (M1-like) phenotype; however, reducing the systemic side effects of these therapies and enabling their delivery to TAMs has remained a challenge. Methods: Here, we develop R848-Ad, an adamantane-modified derivative of the toll-like receptor (TLR) 7/8 agonist resiquimod (R848) through iterative drug screening against reporter cell lines. The adamantane undergoes guest-host interaction with cyclodextrin nanoparticles (CDNPs), enabling drug loading under aqueous conditions and TAM-targeted drug delivery. Therapeutic efficacy and systemic side effects were examined in a murine MC38 cancer model. Results: R848-Ad retained macrophage polarizing activity through agonization of TLR7/8, and the adamantane moiety improved drug affinity for the CDNP. In preclinical studies, nanoformulated R848-Ad resulted in a drastic reduction in measurable systemic effects (loss of body weight) relative to similarly formulated R848 alone while arresting tumor growth. Conclusions: The findings demonstrate the ability of strong nanoparticle-drug interactions to limit systemic toxicity of TLR agonists while simultaneously maintaining therapeutic efficacy.

Tissue-Specific Macrophage Responses to Remote Injury Impact the Outcome of Subsequent Local Immune Challenge.

Myocardial infarction, stroke, and sepsis trigger systemic inflammation and organism-wide complications that are difficult to manage. Here, we examined the contribution of macrophages residing in vital organs to the systemic response after these injuries. We generated a comprehensive catalog of changes in macrophage number, origin, and gene expression in the heart, brain, liver, kidney, and lung of mice with myocardial infarction, stroke, or sepsis. Predominantly fueled by heightened local proliferation, tissue macrophage numbers increased systemically. Macrophages in the same organ responded similarly to different injuries by altering expression of tissue-specific gene sets. Preceding myocardial infarction improved survival of subsequent pneumonia due to enhanced bacterial clearance, which was caused by IFNÉ£ priming of alveolar macrophages. Conversely, EGF receptor signaling in macrophages exacerbated inflammatory lung injury. Our data suggest that local injury activates macrophages in remote organs and that targeting macrophages could improve resilience against systemic complications following myocardial infarction, stroke, and sepsis.