The site of tumor development determines immunogenicity via temporal mobilization of antigen-laden dendritic cells in draining lymph nodes

Enhanced oral versus flank lymph node T cell response parallels anti-PD1 efficacy in head and neck cancer

OBJECTIVES

Understanding head and neck tissue specific immune responses is important for elucidating immunotherapy resistance mechanisms to head and neck squamous cell carcinoma (HNSCC). In this study, we aimed to investigate HNSCC-specific immune response differences between oral and subcutaneous flank tumor transplantation in preclinical models.

MATERIALS AND METHODS

The MOC1 syngeneic mouse oral carcinoma cell line or versions expressing either the H2Kb-restricted SIINFEKL peptide from ovalbumin (MOC1OVA) or ZsGreen (MOC1ZsGreen) were inoculated into mouse oral mucosa (buccal space) or subcutaneous flank and compared for immune cell kinetics in tumors and tumor-draining lymph nodes (TDLNs) and for anti-PD1 response.

RESULTS

Compared to subcutaneous flank tumors, orthotopic oral MOC1OVA induced a higher number of OVA-specific T cells, PD1 + or CD69 + activated OVA-specific T cells in both primary tumors and TDLNs. Tumors were also larger in the flank site and CD8 depletion eliminated the difference in tumor weight between the two sites. Oral versus flank SIINFEKL peptide vaccination showed enhanced TDLN lymphocyte response in the former site. Notably, cDC1 from oral TDLN showed enhanced antigen uptake and co-stimulatory marker expression, resulting in elicitation of an increased antigen specific T cell response and increased activated T cells. Parental MOC1 in the oral site showed increased endogenous antigen-reactive T cells in TDLNs and anti-PD1 blockade rejected oral MOC1 tumors but not subcutaneous flank MOC1.

CONCLUSION

Collectively, we find distinct immune responses between orthotopic oral and heterotopic subcutaneous models, including priming by cDC1 in TDLN, revealing important implications for head and neck cancer preclinical studies.

From pain to tumor immunity: influence of peripheral sensory neurons in cancer

The nervous and immune systems are the primary sensory interfaces of the body, allowing it to recognize, process, and respond to various stimuli from both the external and internal environment. These systems work in concert through various mechanisms of neuro-immune crosstalk to detect threats, provide defense against pathogens, and maintain or restore homeostasis, but can also contribute to the development of diseases. Among peripheral sensory neurons (PSNs), nociceptive PSNs are of particular interest. They possess a remarkable capability to detect noxious stimuli in the periphery and transmit this information to the brain, resulting in the perception of pain and the activation of adaptive responses. Pain is an early symptom of cancer, often leading to its diagnosis, but it is also a major source of distress for patients as the disease progresses. In this review, we aim to provide an overview of the mechanisms within tumors that are likely to induce cancer pain, exploring a range of factors from etiological elements to cellular and molecular mediators. In addition to transmitting sensory information to the central nervous system, PSNs are also capable, when activated, to produce and release neuropeptides (e.g., CGRP and SP) from their peripheral terminals. These neuropeptides have been shown to modulate immunity in cases of inflammation, infection, and cancer. PSNs, often found within solid tumors, are likely to play a significant role in the tumor microenvironment, potentially influencing both tumor growth and anti-tumor immune responses. In this review, we discuss the current state of knowledge about the degree of sensory innervation in tumors. We also seek to understand whether and how PSNs may influence the tumor growth and associated anti-tumor immunity in different mouse models of cancer. Finally, we discuss the extent to which the tumor is able to influence the development and functions of the PSNs that innervate it.

A Pilot Study to Develop Paraneoplastic Cerebellar Degeneration Mouse Model

Modeling paraneoplastic neurological diseases to understand the immune mechanisms leading to neuronal death is a major challenge given the rarity and terminal access of patients' autopsies. Here, we present a pilot study aiming at modeling paraneoplastic cerebellar degeneration with Yo autoantibodies (Yo-PCD). Female mice were implanted with an ovarian carcinoma cell line expressing CDR2 and CDR2L, the known antigens recognized by anti-Yo antibodies. To boost the immune response, we also immunized the mice by injecting antigens with diverse adjuvants and immune checkpoint inhibitors. Ataxia and gait instability were assessed in treated mice as well as autoantibody levels, Purkinje cell density, and immune infiltration in the cerebellum. We observed the production of anti-Yo antibodies in the CSF and serum of all immunized mice. Brain immunoreaction varied depending on the site of implantation of the tumor, with subcutaneous administration leading to a massive infiltration of immune cells in the meningeal spaces, choroid plexus, and cerebellar parenchyma. However, we did not observe massive Purkinje cell death nor any motor impairments in any of the experimental groups. Self-sustained neuro-inflammation might require a longer time to build up in our model. Unusual tumor antigen presentation and/or intrinsic, species-specific factors required for pro-inflammatory engagement in the brain may also constitute strong limitations to achieve massive recruitment of antigen-specific T-cells and killing of antigen-expressing neurons in this mouse model.

Intratumoral injection of TLR9 agonist promotes an immunopermissive microenvironment transition and causes cooperative antitumor activity in combination with anti-PD1 in pancreatic cancer

Background

Complex tumor and immune microenvironment render pancreatic ductal adenocarcinoma (PDAC) resistant to immune checkpoint inhibitors (ICIs). Therefore, a strategy to convert the immune hostile into an immunopermissive tumor is required. Recent studies showed that intratumoral injection of Toll-like receptor 9 agonist IMO-2125 primes the adaptive immune response. Phase I and II trials with intratumoral IMO-2125 demonstrated its safety and antitumoral activity.

Methods

We generated an array of preclinical models by orthotopically engrafting PDAC-derived cell lines in syngeneic mice and categorized them as high, low and no immunogenic potential, based on the ability of tumor to evoke T lymphocyte or NK cell response. To test the antitumor efficacy of IMO-2125 on locally treated and distant sites, we engrafted cancer cells on both flanks of syngeneic mice and treated them with intratumoral IMO-2125 or vehicle, alone or in combination with anti-PD1 ICI. Tumor tissues and systemic immunity were analyzed by transcriptomic, cytofluorimetric and immunohistochemistry analysis.

Results

We demonstrated that intratumoral IMO-2125 as single agent triggers immune system response to kill local and distant tumors in a selected high immunogenic subtype affecting tumor growth and mice survival. Remarkably, intratumoral IMO-2125 in combination with systemic anti-PD1 causes a potent antitumor effect on primary injected and distant sites also in pancreatic cancer models with low immunogenic potential, preceded by a transition toward an immunopermissive microenvironment, with increase in tumor-infiltrating dendritic and T cells in tumor and lymph nodes.

Conclusion

We demonstrated a potent antitumor activity of IMO-2125 and anti-PD1 combination in immunotherapy-resistant PDAC models through the modulation of immune microenvironment, providing the rationale to translate this strategy into a clinical setting.

Depth of tumor implantation affects response to in situ vaccination in a syngeneic murine melanoma model

An important component of research using animal models is ensuring rigor and reproducibility. This study was prompted after two experimenters performing virtually identical studies obtained different results when syngeneic B78 murine melanoma cells were implanted into the skin overlying the flank and treated with an in situ vaccine (ISV) immunotherapy. Although both experimenters thought they were using identical technique, we determined that one was implanting the tumors intradermally (ID) and the other was implanting them subcutaneously (SC). Though the baseline in vivo immunogenicity of tumors can depend on depth of their implantation, the response to immunotherapy as a function of tumor depth, particularly in immunologically 'cold' tumors, has not been well studied. The goal of this study was to evaluate the difference in growth kinetics and response to immunotherapy between identically sized melanoma tumors following ID versus SC implantation. We injected C57BL/6 mice with syngeneic B78 melanoma cells either ID or SC in the flank. When tumors reached 190-230 mm3, they were grouped into a 'wave' and treated with our previously published ISV regimen (12 Gy local external beam radiation and intratumoral hu14.18-IL2 immunocytokine). Physical examination demonstrated that ID-implanted tumors were mobile on palpation, while SC-implanted tumors became fixed to the underlying fascia. Histologic examination identified a critical fascial layer, the panniculus carnosus, which separated ID and SC tumors. SC tumors reached the target tumor volume significantly faster compared with ID tumors. Most ID tumors exhibited either partial or complete response to this immunotherapy, whereas most SC tumors did not. Further, the 'mobile' or 'fixed' phenotype of tumors predicted response to therapy, regardless of intended implantation depth. These findings were then extended to additional immunotherapy regimens in four separate tumor models. These data indicate that the physical 'fixed' versus 'mobile' characterization of the tumors may be one simple method of ensuring homogeneity among implanted tumors prior to initiation of treatment. Overall, this short report demonstrates that small differences in depth of tumor implantation can translate to differences in response to immunotherapy, and proposes a simple physical examination technique to ensure consistent tumor depth when conducting implantable tumor immunotherapy experiments.

Immunization with alloantibodies-covered melanoma cells induces regional antitumor effects that become systemic when combined with 5-FU treatment

Alloantibodies, in particular immunoglobulin G (allo-IgG), confer a rejection advantage to tumors sharing the same major histocompatibility complex (MHC) in mice. However, when administrated intratumorally, this effect can only be achieved in combination with dendritic cells (DCs) activation. Here, we developed high titer allo-IgG by multiple rounds of immunization with allogenic B16 melanoma cells, which allows for the strong binding with B16 cells. We demonstrate that B16 cells incubated with these allo-IgG (referred to as allo-IgG-B16) become highly immunogenic, which release tumor antigens that are efficiently presented by classic DCs in lymph nodes (LNs). Injection of allo-IgG-B16 turns the tumor into an immune hot one and even elicits a systemic antitumor response when used together with 5-fluorouracil (5-FU). This systemic response is tumor-specific and relies on the critical site - LNs. Our findings provide a rationale for the use of allo-IgG in cancer treatment.

The immuno-oncological implications of insulin

Emerging evidence has implicated insulin in regulating the phenotypes of various immune cells through canonical downstream signalling effectors of insulin, namely, the PI3K/Akt/mTOR pathway. Notably, these signalling components also exhibit crosstalk with other immune signalling pathways, such as the JAK/STAT pathway (activated by cytokines and growth factors), and, importantly, are also negatively regulated by the immune checkpoint blockers (ICBs), PD-1 and CTLA-4. Here, we point out recent findings, suggesting that insulin may promote a pro-inflammatory phenotype with potential implications on ICB therapy. As an example, the contemporary paradigm holds that, while T cell receptor recognition of distinct MHC-expressed epitopes ensures specificity, co-activation of CD28 along with signal inputs form various cytokines and insulin operates to 'fine-tune' the immune response via PI3K and other downstream signalling molecules. These considerations highlight the urgent need for focused investigations into the role of insulin in regulating immune cell function in the context of ICB therapies.

Preclinical murine tumor models: a structural and functional perspective

The goal of this review is to pinpoint the specific features, including the weaknesses, of various tumor models, and to discuss the reasons why treatments that are efficient in murine tumor models often do not work in clinics. In a detailed comparison of transplanted and spontaneous tumor models, we focus on structure-function relationships in the tumor microenvironment. For instance, the architecture of the vascular tree, which depends on whether tumor cells have gone through epithelial-mesenchymal transition, is determinant for the extension of the spontaneous necrosis, and for the intratumoral localization of the immune infiltrate. Another key point is the model-dependent abundance of TGFβ in the tumor, which controls the variable susceptibility of different tumor models to treatments. Grounded in a historical perspective, this review provides a rationale for checking factors that will be key for the transition between preclinical murine models and clinical applications.

TGFβ blocks IFNα/β release and tumor rejection in spontaneous mammary tumors

Type I interferons (IFN) are being rediscovered as potent anti-tumoral agents. Activation of the STimulator of INterferon Genes (STING) by DMXAA (5,6-dimethylxanthenone-4-acetic acid) can induce strong production of IFNα/β and rejection of transplanted primary tumors. In the present study, we address whether targeting STING with DMXAA also leads to the regression of spontaneous MMTV-PyMT mammary tumors. We show that these tumors are refractory to DMXAA-induced regression. This is due to a blockade in the phosphorylation of IRF3 and the ensuing IFNα/β production. Mechanistically, we identify TGFβ, which is abundant in spontaneous tumors, as a key molecule limiting this IFN-induced tumor regression by DMXAA. Finally, blocking TGFβ restores the production of IFNα by activated MHCII⁺ tumor-associated macrophages, and enables tumor regression induced by STING activation. On the basis of these findings, we propose that type I IFN-dependent cancer therapies could be greatly improved by combinations including the blockade of TGFβ.

Skin tumor immunity: Site does matter for antigen presentation by DCs

The immune system has the ability to specifically identify and eliminate tumors, but the underlying mechanisms responsible for this phenomenon are not fully understood. A study published in this issue of the European Journal of Immunology now provides new insights into this important problem. Joncker et al. [Eur. J. Immunol. 2016. 46: 609-618] show that the timely mobilization of tumor antigen-bearing dendritic cells (DCs) from the periphery to the lymph nodes is critical for effective antitumor T-cell immunity, and that DCs present tumor antigens much more efficiently when encountered in the skin rather than in the subcutaneous tissues.