Immune surveillance against a solid tumor fails because of immunological ignorance

Control of aggressive 4T1-luc metastatic breast cancer using immunogenic cell lysates generated with methotrexate

This study investigated a novel immunization therapy for pre-clinical aggressive metastatic breast cancer using immunogenic cell lysates derived from 4T1-luc cells treated with cisplatin and methotrexate, addressing the critical need for improved treatments given the poor prognosis associated with breast cancer metastasis and its significant mortality rate. Methotrexate, a conventional cytotoxic agent, demonstrated a previously unrecognized capacity to induce immunogenic cell lysates, presenting a potential drug repositioning opportunity. In a murine model of stage IV metastatic breast cancer, immunization with these lysates significantly reduced primary tumor growth and lung metastasis, as assessed by bioluminescence imaging. Immunization also modulated immune cell populations, reducing splenomegaly and hepatomegaly, and partially reversing the immunosuppressive phenotype associated with 4T1-luc tumor growth, as evidenced by cytokine profiling (IL-6 and IFN-γ) and flow cytometry analysis of CD4 + and CD8 + T cell subpopulations. Specifically, methotrexate-treated lysates induced a significant shift in CD4 + T cells towards an effector phenotype. These findings highlight the potential of this immunotherapy approach to improve breast cancer treatment outcomes and warrant further investigation.

Infection of tumor cells with Salmonella typhimurium mimics immunogenic cell death and elicits tumor-specific immune responses

Some properties of Salmonella-infected cells overlap with immunogenic cell death. In this study, we demonstrated that intracellular infection of melanoma with Salmonella typhimurium induced high immunogenicity in melanoma cells, leading to antitumor effects with melanoma-antigen-specific T-cell responses. Murine B16F10 melanoma cells were infected with tdTomato-expressing attenuated S. typhimurium (VNP20009; VNP-tdT), triggering massive cell vacuolization. VNP-tdT-infected B16F10 cells were phagocytosed efficiently, which induced the activation of antigen-presenting cells with CD86 expression in vitro. Subcutaneous coimplantation of uninfected and VNP-tdT-infected B16F10 cells into C57BL/6 mice significantly suppressed tumor growth compared with the implantation of uninfected B16F10 cells alone. Inoculation of mice with VNP-tdT-infected B16F10 cells elicited the proliferation of melanoma-antigen (gp100)-specific T cells, and it protected the mice from the second tumor challenge of uninfected B16F10 cells. These results suggest that Salmonella-infected tumor cells acquire effective adjuvanticity, leading to ideal antitumor immune responses.

Hapten/Myristoyl Functionalized Poly(propyleneimine) Dendrimers as Potent Cell Surface Recruiters of Antibodies for Mediating Innate Immune Killing

Recruiting endogenous antibodies to the surface of cancer cells using antibody-recruiting molecules has the potential to unleash innate immune effector killing mechanisms against antibody-bound cancer cells. The affinity of endogenous antibodies is relatively low, and many currently explored antibody-recruiting strategies rely on targeting over-expressed receptors, which have not yet been identified in most solid tumors. Here, both challenges are addressed by functionalizing poly(propyleneimine) (PPI) dendrimers with both multiple dinitrophenyl (DNP) motifs, as anti-hapten antibody-recruiting motifs, and myristoyl motifs, as universal phospholipid cell membrane anchoring motifs, to recruit anti-hapten antibodies to cell surfaces. By exploiting the multivalency of the ligand exposure on the dendrimer scaffold, it is demonstrated that dendrimers featuring ten myristoyl and six DNP motifs exhibit the highest antibody-recruiting capacity in vitro. Furthermore, it is shown that treating cancer cells with these dendrimers in vitro marks them for phagocytosis by macrophages in the presence of anti-hapten antibodies. As a proof-of-concept, it is shown that intratumoral injection of these dendrimers in vivo in tumor-bearing mice results in the recruitment of anti-DNP antibodies to the cell surface in the tumor microenvironment. These findings highlight the potential of dendrimers as a promising class of novel antibody-recruiting molecules for use in cancer immunotherapy.

Changes of immune microenvironment in head and neck squamous cell carcinoma in 3D-4-culture compared to 2D-4-culture

BACKGROUND

The immune system plays a crucial role in initiating, progressing, and disseminating HNSCC. This study aims to investigate the differences in immune microenvironments between 2D-4-culture and 3D-4-culture models of head and neck squamous cell carcinoma (HNSCC) cells (FaDu), human fibroblasts (HF), human monocytes (THP-1), and human endothelial cells (HUVEC).

METHODS

For the 3D-4-culture model, FaDu:HF:THP-1 (2:1:1) were inoculated in an ultra-low attachment culture plate, while HUVECs were placed in a transwell chamber. The ordinary culture plate was used for the 2D-4-culture model. Tumor-associated macrophage markers (CD163), tumor-associated fibroblast markers (FAP), and epithelial-mesenchymal transition (EMT) were detected by western blot. Inflammatory cytokines (IL-4, IL-2, CXCL 10, IL-1 β, TNF-α, CCL 2, IL-17 A, IL-6, IL-10, IFN-γ, IL-12 p 70, CXCL 8, TGFβ1) in the supernatant were measured by flow cytometry. HUVEC migration was observed under a microscope. The 3D spheres were stained and observed with a confocal microscope. CCK8 assay was used to detect the resistance of mixed cells to cisplatin in both 2D-4-culture and 3D-4-culture.

RESULTS

After three days of co-culture, the 3D-4-culture model showed increased expression levels of CD163 and FAP proteins (both P < 0.001), increased expression of E-cadherin protein and N-cadherin protein expression (P < 0.001), decreased expression of vimentin (P < 0.01) and Twist protein (P < 0.001). HUVEC migration significantly increased (P < 0.001), as did the concentrations of IP-10, MCP-1, IL-6, and IL-8 (all P < 0.001). Confocal microscopy showed that 3D-4-culture formed loose cell clusters on day 1, which gradually became a dense sphere surrounded by FaDu cells invading the inside. After co-culturing for 24 h, 48 h, and 72 h, the resistance of mix cells to cisplatin in 3D-4-culture was significantly higher than in 2D-4-culture (P < 0.01 for all).

CONCLUSION

Compared to 2D-4-culture, 3D-4-culture better simulates the in vivo immune microenvironment of HNSCC by promoting fibroblast transformation into tumor-associated fibroblasts, monocyte transformation into tumor-associated macrophages, enhancing endothelial cell migration ability, partial EMT formation in HNSCC cells, and is more suitable for studying the immunosuppressive microenvironment of HNSCC.

T Cells in Colorectal Cancer: Unravelling the Function of Different T Cell Subsets in the Tumor Microenvironment

Therapeutic options for metastatic colorectal cancer (mCRC) are very limited, and the prognosis using combination therapy with a chemotherapeutic drug and a targeted agent, e.g., epidermal growth factor receptor or tyrosine kinase, remains poor. Therefore, mCRC is associated with a poor median overall survival (mOS) of only 25-30 months. Current immunotherapies with checkpoint inhibitor blockade (ICB) have led to a substantial change in the treatment of several cancers, such as melanoma and non-small cell lung cancer. In CRC, ICB has only limited effects, except in patients with microsatellite instability-high (MSI-H) or mismatch repair-deficient (dMMR) tumors, which comprise about 15% of sporadic CRC patients and about 4% of patients with metastatic CRC. The vast majority of sporadic CRCs are microsatellite-stable (MSS) tumors with low levels of infiltrating immune cells, in which immunotherapy has no clinical benefit so far. Immunotherapy with checkpoint inhibitors requires the presence of infiltrating T cells into the tumor microenvironment (TME). This makes T cells the most important effector cells in the TME, as evidenced by the establishment of the immunoscore-a method to estimate the prognosis of CRC patients. The microenvironment of a tumor contains several types of T cells that are anti-tumorigenic, such as CD8⁺ T cells or pro-tumorigenic, such as regulatory T cells (Tregs) or T helper 17 (Th17) cells. However, even CD8⁺ T cells show marked heterogeneity, e.g., they can become exhausted, enter a state of hyporesponsiveness or become dysfunctional and express high levels of checkpoint molecules, the targets for ICB. To kill cancer cells, CD8⁺ T cells need the recognition of the MHC class I, which is often downregulated on colorectal cancer cells. In this case, a population of unconventional T cells with a γδ T cell receptor can overcome the limitations of the conventional CD8⁺ T cells with an αβT cell receptor. γδ T cells recognize antigens in an MHC-independent manner, thus acting as a bridge between innate and adaptive immunity. Here, we discuss the effects of different T cell subsets in colorectal cancer with a special emphasis on γδ T cells and the possibility of using them in CAR-T cell therapy. We explain T cell exclusion in microsatellite-stable colorectal cancer and the possibilities to overcome this exclusion to enable immunotherapy even in these "cold" tumors.

Targeting protein tyrosine phosphatases for CDK6-induced immunotherapy resistance

Elucidating the mechanisms of resistance to immunotherapy and developing strategies to improve its efficacy are challenging goals. Bioinformatics analysis demonstrates that high CDK6 expression in melanoma is associated with poor progression-free survival of patients receiving single-agent immunotherapy. Depletion of CDK6 or cyclin D3 (but not of CDK4, cyclin D1, or D2) in cells of the tumor microenvironment inhibits tumor growth. CDK6 depletion reshapes the tumor immune microenvironment, and the host anti-tumor effect depends on cyclin D3/CDK6-expressing CD8+ and CD4+ T cells. This occurs by CDK6 phosphorylating and increasing the activities of PTP1B and T cell protein tyrosine phosphatase (TCPTP), which, in turn, decreases tyrosine phosphorylation of CD3ζ, reducing the signal transduction for T cell activation. Administration of a PTP1B and TCPTP inhibitor prove more efficacious than using a CDK6 degrader in enhancing T cell-mediated immunotherapy. Targeting protein tyrosine phosphatases (PTPs) might be an effective strategy for cancer patients who resist immunotherapy treatment.

Effector Memory T Cells and CD45RO+ Regulatory T Cells in Metastatic vs. Non-Metastatic Lymph Nodes in Lung Cancer Patients

Lymphocytes play a leading role in regulation of the immune system in lung cancer patients. The recognition of T cells profile may help in prediction of effectiveness of anticancer immunotherapy. The aim of the study was to determine the dominant subpopulation of CD4+ and CD8+ lymphocytes in metastatic and non-metastatic lymph nodes (LNs) of lung cancer patients. LNs aspirates were obtained during EBUS/TBNA procedure and cells were analyzed by flow cytometry. We showed a higher percentage of CD4+ and CD8+ effector memory T cells in the metastatic than in the non-metastatic LNs (28.6 vs. 15.3% and 28.6 vs. 14.0%, p< 0.05). The proportion of CD45RO+ T regulatory cells (CD45RO+ Tregs) was higher in the metastatic LNs than in the non-metastatic ones (65.6 vs. 31%, p< 0.05). We reported the significant differences in T cell subsets depending on the lung cancer metastatic process. We observed that the effector memory T cells were predominant subpopulations in metastatic LNs. Lymphocyte profile in LNs is easy to evaluate by flow cytometry of EBUS/TBNA samples and may reflect the immune status in lung cancer.

CD8+ T cell differentiation and dysfunction in cancer

CD8⁺ T cells specific for cancer cells are detected within tumours. However, despite their presence, tumours progress. The clinical success of immune checkpoint blockade and adoptive T cell therapy demonstrates the potential of CD8⁺ T cells to mediate antitumour responses; however, most patients with cancer fail to achieve long-term responses to immunotherapy. Here we review CD8⁺ T cell differentiation to dysfunctional states during tumorigenesis. We highlight similarities and differences between T cell dysfunction and other hyporesponsive T cell states and discuss the spatio-temporal factors contributing to T cell state heterogeneity in tumours. An important challenge is predicting which patients will respond to immunotherapeutic interventions and understanding which T cell subsets mediate the clinical response. We explore our current understanding of what determines T cell responsiveness and resistance to immunotherapy and point out the outstanding research questions.

The Dynamic Entropy of Tumor Immune Infiltrates: The Impact of Recirculation, Antigen-Specific Interactions, and Retention on T Cells in Tumors

Analysis of tumor infiltration using conventional methods reveals a snapshot view of lymphocyte interactions with the tumor environment. However, lymphocytes have the unique capacity for continued recirculation, exploring varied tissues for the presence of cognate antigens according to inflammatory triggers and chemokine gradients. We discuss the role of the inflammatory and cellular makeup of the tumor environment, as well as antigen expressed by cancer cells or cross-presented by stromal antigen presenting cells, on recirculation kinetics of T cells. We aim to discuss how current cancer therapies may manipulate lymphocyte recirculation versus retention to impact lymphocyte exclusion in the tumor.

Defining Immunogenic and Radioimmunogenic Tumors

In the cancer literature tumors are inconsistently labeled as ‘immunogenic’, and experimental results are occasionally dismissed since they are only tested in known ‘responsive’ tumor models. The definition of immunogenicity has moved from its classical definition based on the rejection of secondary tumors to a more nebulous definition based on immune infiltrates and response to immunotherapy interventions. This review discusses the basis behind tumor immunogenicity and the variation between tumor models, then moves to discuss how these principles apply to the response to radiation therapy. In this way we can identify radioimmunogenic tumor models that are particularly responsive to immunotherapy only when combined with radiation, and identify the interventions that can convert unresponsive tumors so that they can also respond to these treatments.

Biomechanics of T Cell Dysfunctions in Chronic Diseases

Understanding the mechanisms behind T cell dysfunctions during chronic diseases is critical in developing effective immunotherapies. As demonstrated by several animal models and human studies, T cell dysfunctions are induced during chronic diseases, spanning from infections to cancer. Although factors governing the onset and the extent of the functional impairment of T cells can differ during infections and cancer, most dysfunctional phenotypes share common phenotypic traits in their immune receptor and biophysical landscape. Through the latest developments in biophysical techniques applied to explore cell membrane and receptor-ligand dynamics, we are able to dissect and gain further insights into the driving mechanisms behind T cell dysfunctions. These insights may prove useful in developing immunotherapies aimed at reinvigorating our immune system to fight off infections and malignancies more effectively. The recent success with checkpoint inhibitors in treating cancer opens new avenues to develop more effective, targeted immunotherapies. Here, we highlight the studies focused on the transformation of the biophysical landscape during infections and cancer, and how T cell biomechanics shaped the immunopathology associated with chronic diseases.

Tumor cells, rather than dendritic cells, deliver antigen to the lymph node for cross-presentation

It is widely accepted that generation of tumor specific CD8+ T-cell responses occur via cross-priming; however the source of tumor antigen for this event is unknown. We examined the source and form of tumor antigen required for cross-presentation in the local lymph node (LN) using a syngeneic mouse tumor model expressing a marker antigen. We found that cross-presentation of this model tumor antigen in the LN is dependent on continuous traffic of antigen from the tumor site, but without any detectable migration of tumor resident dendritic cells (DCs). Instead, small numbers of tumor cells metastasize to local LNs where they are exposed to a localized CTL attack, resulting in delivery of tumor antigen into the cross-presentation pathway.

Cellular cytotoxicity is a form of immunogenic cell death

Background

The immune response to cancer is often conceptualized with the cancer immunity cycle. An essential step in this interpretation is that antigens released by dying tumors are presented by dendritic cells to naive or memory T cells in the tumor-draining lymph nodes. Whether tumor cell death resulting from cytotoxicity, as mediated by T cells or natural killer (NK) lymphocytes, is actually immunogenic currently remains unknown.

Methods

In this study, tumor cells were killed by antigen-specific T-cell receptor (TCR) transgenic CD8 T cells or activated NK cells. Immunogenic cell death was studied analyzing the membrane exposure of calreticulin and the release of high mobility group box 1 (HMGB1) by the dying tumor cells. Furthermore, the potential immunogenicity of the tumor cell debris was evaluated in immunocompetent mice challenged with an unrelated tumor sharing only one tumor-associated antigen and by class I major histocompatibility complex (MHC)-multimer stainings. Mice deficient in Batf3, Ifnar1 and Sting1 were used to study mechanistic requirements.

Results

We observe in cocultures of tumor cells and effector cytotoxic cells, the presence of markers of immunogenic cell death such as calreticulin exposure and soluble HMGB1 protein. Ovalbumin (OVA)-transfected MC38 colon cancer cells, exogenously pulsed to present the gp100 epitope are killed in culture by mouse gp100-specific TCR transgenic CD8 T cells. Immunization of mice with the resulting destroyed cells induces epitope spreading as observed by detection of OVA-specific T cells by MHC multimer staining and rejection of OVA⁺ EG7 lymphoma cells. Similar results were observed in mice immunized with cell debris generated by NK-cell mediated cytotoxicity. Mice deficient in Batf3-dependent dendritic cells (conventional dendritic cells type 1, cDC1) fail to develop an anti-OVA response when immunized with tumor cells killed by cytotoxic lymphocytes. In line with this, cultured cDC1 dendritic cells uptake and can readily cross-present antigen from cytotoxicity-killed tumor cells to cognate CD8⁺ T lymphocytes.

Conclusion

These results support that an ongoing cytotoxic antitumor immune response can lead to immunogenic tumor cell death.

Clinical significance of CD38 and CD101 expression in PD-1+CD8+ T cells in patients with epithelial ovarian cancer

Previous studies using mouse liver tumor models have indicated that coexpression of CD38 and CD101 in programmed cell death-1 (PD-1)⁺CD8⁺ T cells may reflect fixed dysregulation of CD8⁺ T cells and thus indicate a poor response to anti-PD-1 immunotherapy. However, whether CD38 and CD101 expression in PD-1⁺CD8⁺ T cells can predict the clinical status and efficacy of chemotherapy for various cancer types, including ovarian cancer (OC), remains unclear. In the present study, peripheral blood mononuclear cells (PBMCs) were obtained by Ficoll-Hypaque gradient centrifugation from 96 fresh samples from healthy adult volunteers and patients with epithelial OC, aged 55.21±9.91 years. Additionally, tumor-infiltrating lymphocytes (TILs) were separated using a combination of mechanical, chemical and enzymatic digestion from fresh surgically removed tumor tissues from 15 patients with epithelial OC. The expression of CD38 and CD101 in PD-1⁺CD8⁺ T cells or TILs was detected by flow cytometry or immunofluorescence (IF) staining, respectively. The association between the level of CD38/CD101 expression and clinicopathological parameters or postoperative chemotherapy in patients with OC was statistically analyzed. The levels of CD38/CD101-coexpressing PD-1⁺CD8⁺ T cells were significantly increased in PBMCs and TILs of patients with OC compared with those of healthy volunteers. The frequency of PD-1⁺CD38⁺CD101⁺CD8⁺ T cells among the total PD-1⁺CD8⁺ T cell subpopulation was negatively associated with clinical stage, lymph node metastasis and postoperative chemotherapy prognosis in patients with OC. Furthermore, IF staining confirmed colocalization of CD38 and CD101 on the majority of TILs in OC tissues. Thus, the present study suggests that coexpression of CD38 and CD101 in peripheral PD-1⁺CD8⁺ T cells and TILs may serve as a new indicator for diagnosis and treatment efficacy in patients with epithelial OC.

Using Preclinical Data to Design Combination Clinical Trials of Radiation Therapy and Immunotherapy

Immunotherapies are rapidly entering the clinic as approved treatments for diverse cancer pathologies. Radiation therapy is an integral partner in cancer therapy, commonly as part of complicated multimodality approaches that optimize patient outcomes. Preclinical studies have demonstrated that the success of radiation therapy in tumor control is due in part to immune mechanisms, and that outcomes following radiation therapy can be improved through combination with a range of immunotherapies. However, preclinical models of cancer are very different from patient tumors, and the way these preclinical tumors are treated is often very different from standard of care treatment of patients. This review examines the preclinical and clinical data for the role of the immune system in radiation therapy outcomes, and how to integrate preclinical findings into clinical trials, using ongoing studies as examples.

Dual-target IL-12-containing nanoparticles enhance T cell functions for cancer immunotherapy

Cytotoxic T lymphocytes (CTLs) play a major role in cancer immunotherapy. A potent tumor immunotherapy may not only require activation of anti-tumor effector cells but also rely on the use of cytokines to create a controlled environment for the development of anti-tumor T cells. In this study, we fabricated a dual-target immunonanoparticle, e.g. poly(d,l-lactide-co-glycolide) nanoparticle, by loading Interleukin-12 (IL-12) and modifying with CD8 and Glypican-3 antibodies on the surface. Our results demonstrate that the fabricated targeting immunonanoparticles bind specifically to the two target cells of interest, i.e. CD8+ T cells and HepG-2 cells via the antibody-antigen interactions and form T cell-HepG-2 cell clusters, which enhances the cytotoxicity of T cells. IL-12-containing dual-target immunonanoparticles delivered IL-12 specifically to CD8+ T cells, and favored the expansion, activation and cytotoxic activity of CD8+ T lymphocytes. These results suggest that dual-target IL-12-encapsulated nanoparticles are a promising platform for cancer immunotherapy.

Impact of TCR Diversity on the Development of Transplanted or Chemically Induced Tumors

Burnet postulated that the diversity of T-cell receptors (TCR) allows T cells to protect against the development of cancers that display antigens with a similar, seemingly endless diversity. To test this hypothesis, we developed a strategy in which a single breeding pair of mice gives rise to four groups of sibling mice. Three of the four groups had a similar number of CD8⁺ T cells, but TCR diversity was either broad, significantly reduced, or absent when expressing only one type of TCR. The fourth group had no T cells. All mice shared the same housing, and, therefore, their microbial environment was similar. Only slight differences in the intestinal flora were observed under these conditions. An undisturbed broad TCR repertoire was required for the rejection of inoculated cancers displaying the natural antigenic heterogeneity of primary tumors, whereas even one type of TCR was sufficient to protect against artificial cancers stably expressing cognate antigens. The three groups of mice with limited or no TCR repertoire showed an increased risk of developing primary tumors after chemical induction. However, the risk of early death or morbidity in these cohorts of mice was significantly higher than in mice with a diverse TCR repertoire, and it remains unknown whether mice with reduced TCR diversity, who died early without cancer, would have developed tumors with higher, lower, or equal probability after induction. Together, TCR diversity seems crucial to overcome the natural genetic instability of cancers and their antigenic heterogeneity, which impacts the design of cellular therapies.

A rationale for surgical debulking to improve anti-PD1 therapy outcome in non small cell lung cancer

Anti-PD1 immunotherapy has emerged as a gold-standard treatment for first- or second-line treatment of stage IV NSCLC, with response rates ranging from 10 to 60%. Strategies to improve the disease control rate are needed. Several reports suggested that debulking surgery enhances anti-tumor immunity. We aimed at examining tumor burden as a predictive factor of anti-PD1 tretment efficacy and to evaluate the role of cytoreductive surgery in anti-PD1 treated NSCLC. Immunocompetent DBA/2 mice engrafted with various amount of allogeneic lung squamous cancer KLN-205 cells were treated with anti-PD1 monoclonal antibody. Mice engrafted with two tumors also underwent a debulking surgery or a sham procedure. Tumor volume was monitored to assess treatment efficacy. Tumor infiltrating lymphocytes were assessed by flow cytometry. In a retrospective study of 48 stage IV NSCLC patients treated with Nivolumab who underwent a 18-FDG PETscan before treatment onset, the prognostic role of metabolic tumor volume was analysed. Anti-PD1 treatment effect was greater in mice bearing smaller tumors. Treatment with higher doses of anti-PD1 antibody did not improve the outcome, independently of the size of the tumor. In mice bearing 2 tumors, excision of 1 tumor improved the anti-PD1 treatment effect on the remaining tumor. In 48 NSCLC patients receiving anti-PD1 treatment, high metabolic tumor volume was associated with poor overall survival and the absence of clinical benefit. Treg infiltration, but not effector T cells, was positively correlated to tumor volume. Taken together, our results suggest that tumor volume is a predictive factor of anti-PD1 efficacy in NSCLC. Additionally, an experimental murine model suggests that tumor debulking may improve control of residual tumor.

Simple strategy for single-chain fragment antibody-conjugated probe construction

AIMS

A combination of biomarker and instrument technology diagnosis methods, especially antigen-targeted imaging methods, is required to increase the accuracy of the diagnosis of cancer. Currently, the targeting efficiency is limited by the conjugation methods used for the conjugation of antibodies and imaging materials. Here, a simple strategy for the conjugation of a probe and a single-chain fragment antibody (scFv) that does not change the characteristics of the antibody was shown.

MAIN METHODS

An ScFv was conjugated with superparamagnetic iron oxide (SPIO) or indocyanine green (ICG) via a linker by utilizing the reaction between cysteine and maleimide. The characterization of the probe was performed by flow cytometry, confocal imaging, optical imaging and magnetic resonance imaging (MRI).

KEY FINDINGS

After conjugation, the scFv retained high affinity, antigen specificity, and strong internalization ability. The application of the conjugated probe was also confirmed by optical imaging and MRI.

SIGNIFICANCE

The proposed strategy provides a simple method for the production of high efficiency antigen-targeted imaging probes for tumor diagnosis.

Immunological ignorance is an enabling feature of the oligo-clonal T cell response to melanoma neoantigens

The impact of intratumoral heterogeneity (ITH) and the resultant neoantigen landscape on T cell immunity are poorly understood. ITH is a widely recognized feature of solid tumors and poses distinct challenges related to the development of effective therapeutic strategies, including cancer neoantigen vaccines. Here, we performed deep targeted DNA sequencing of multiple metastases from melanoma patients and observed ubiquitous sharing of clonal and subclonal single nucleotide variants (SNVs) encoding putative HLA class I-restricted neoantigen epitopes. However, spontaneous antitumor CD8+ T cell immunity in peripheral blood and tumors was restricted to a few clonal neoantigens featuring an oligo-/monoclonal T cell-receptor (TCR) repertoire. Moreover, in various tumors of the 4 patients examined, no neoantigen-specific TCR clonotypes were identified despite clonal neoantigen expression. Mature dendritic cell (mDC) vaccination with tumor-encoded amino acid-substituted (AAS) peptides revealed diverse neoantigen-specific CD8+ T responses, each composed of multiple TCR clonotypes. Isolation of T cell clones by limiting dilution from tumor-infiltrating lymphocytes (TILs) permitted functional validation regarding neoantigen specificity. Gene transfer of TCRαβ heterodimers specific for clonal neoantigens confirmed correct TCR clonotype assignments based on high-throughput TCRBV CDR3 sequencing. Our findings implicate immunological ignorance of clonal neoantigens as the basis for ineffective T cell immunity to melanoma and support the concept that therapeutic vaccination, as an adjunct to checkpoint inhibitor treatment, is required to increase the breadth and diversity of neoantigen-specific CD8+ T cells.

Tumor infiltrating lymphocytes: The regulator of melanoma evolution

Melanoma is the most severe type of skin cancer and its incidence has increased in the last decades. In the United States, it is the 6th most common cancer in both men and women. Prognosis for patients with melanoma depends on the stage of the disease at the time of diagnosis and it can be influenced by the immunologic response. Melanoma has been historically considered an immunogenic malignancy. It often contains great amount of immune cells (different subsets of T-cells, dendritic cells, macrophages, neutrophils, mast cells, B lymphocytes), which may reflect a continuous intercommunication between host and tumor. It is not established if tumor-infiltrating lymphocytes (TILs) are induced by tumor cells or by other components of the microenvironment or when they are a host direct immunologic reaction. It has been observed that in many cases, the presence of a dense TIL is associated with good prognosis. The pattern and activation state of the cells which constitute TIL is variable and modulates the clinical outcome. An important step in the understanding of tumor immunobiology is the analysis of the populations and subsets of immune cells that form TIL. Besides its prognostic significance, after approval of cytotoxic T lymphocyte antigen 4, programmed cell death-1 and programmed death-1 ligand antibodies for the treatment of melanoma, the assessment of immune infiltrate composition has become even more captivating, as it could provide new target molecules and new biomarkers for predicting the effect of the treatment and disease outcome in patients treated with immunotherapy. In this review we discuss current state of knowledge in the field of immune cells that infiltrate melanoma, resuming the potential of TIL components to become prognostic markers for natural evolution, for response to drugs or valuable targets for new medication.

Tumor infiltrating lymphocytes: The regulator of melanoma evolution

Melanoma is the most severe type of skin cancer and its incidence has increased in the last decades. In the United States, it is the 6th most common cancer in both men and women. Prognosis for patients with melanoma depends on the stage of the disease at the time of diagnosis and it can be influenced by the immunologic response. Melanoma has been historically considered an immunogenic malignancy. It often contains great amount of immune cells (different subsets of T-cells, dendritic cells, macrophages, neutrophils, mast cells, B lymphocytes), which may reflect a continuous intercommunication between host and tumor. It is not established if tumor-infiltrating lymphocytes (TILs) are induced by tumor cells or by other components of the microenvironment or when they are a host direct immunologic reaction. It has been observed that in many cases, the presence of a dense TIL is associated with good prognosis. The pattern and activation state of the cells which constitute TIL is variable and modulates the clinical outcome. An important step in the understanding of tumor immunobiology is the analysis of the populations and subsets of immune cells that form TIL. Besides its prognostic significance, after approval of cytotoxic T lymphocyte antigen 4, programmed cell death-1 and programmed death-1 ligand antibodies for the treatment of melanoma, the assessment of immune infiltrate composition has become even more captivating, as it could provide new target molecules and new biomarkers for predicting the effect of the treatment and disease outcome in patients treated with immunotherapy. In this review we discuss current state of knowledge in the field of immune cells that infiltrate melanoma, resuming the potential of TIL components to become prognostic markers for natural evolution, for response to drugs or valuable targets for new medication.

MHC/HLA Class I Loss in Cancer Cells

In this chapter I describe Tumour Immune Escape mechanisms associated with MHC/HLA class I loss in human and experimental tumours. Different altered HLA class-I phenotypes can be observed that are produced by different molecular mechanisms. Experimental and histological evidences are summarized indicating that at the early stages of tumour development there is an enormous variety of tumour clones with different MHC class I expression patterns. This phase is followed by a strong T cell mediated immune-selection of MHC/HLA class-I negative tumour cells in the primary tumour lesion. This transition period results in a formation of a tumour composed only of HLA-class I negative cells. An updated description of this process observed in a large variety of human tumors is included. In the second section I focus on MHC/HLA class I alterations observed in mouse and human metastases, and describe the generation of different tumor cell clones with altered MHC class I phenotypes, which could be similar or different from the original tumor clone. The biological and immunological relevance of these observations is discussed. Finally, the interesting phenomenon of metastatic dormancy is analyzed in association with a particular MHC class I negative tumor phenotype.

Activating the Nucleic Acid-Sensing Machinery for Anticancer Immunity

Nucleic acid sensing pathways have likely evolved as part of a broad pathogen sensing strategy intended to discriminate infectious agents and initiate appropriate innate and adaptive controls. However, in the absence of infectious agents, nucleic acid sensing pathways have been shown to play positive and negative roles in regulating tumorigenesis, tumor progression and metastatic spread. Understanding the normal biology behind these pathways and how they are regulated in malignant cells and in the tumor immune environment can help us devise strategies to exploit nucleic acid sensing to manipulate anti-cancer immunity.

Tumor cure by radiation therapy and checkpoint inhibitors depends on pre-existing immunity

Radiation therapy is a source of tumor antigen release that has the potential to serve as an endogenous tumor vaccination event. In preclinical models radiation therapy synergizes with checkpoint inhibitors to cure tumors via CD8 T cell responses. To evaluate the immune response initiated by radiation therapy, we used a range of approaches to block the pre-existing immune response artifact initiated by tumor implantation. We demonstrate that blocking immune responses at tumor implantation blocks development of a tumor-resident antigen specific T cell population and prevents tumor cure by radiation therapy combined with checkpoint immunotherapy. These data demonstrate that this treatment combination relies on a pre-existing immune response to cure tumors, and may not be a solution for patients without pre-existing immunity.

Growth and Immune Evasion of Lymph Node Metastasis

Cancer patients with lymph node (LN) metastases have a worse prognosis than those without nodal disease. However, why LN metastases correlate with reduced patient survival is poorly understood. Recent findings provide insight into mechanisms underlying tumor growth in LNs. Tumor cells and their secreted molecules engage stromal, myeloid, and lymphoid cells within primary tumors and in the lymphatic system, decreasing antitumor immunity and promoting tumor growth. Understanding the mechanisms of cancer survival and growth in LNs is key to designing effective therapy for the eradication of LN metastases. In addition, uncovering the implications of LN metastasis for systemic tumor burden will inform treatment decisions. In this review, we discuss the current knowledge of the seeding, growth, and further dissemination of LN metastases.

Correction to: Characterization of the first fully human anti-TEM1 scFv in models of solid tumor imaging and immunotoxin-based therapy

Tumor endothelial marker 1 (TEM1) has been identified as a novel surface marker upregulated on the blood vessels and stroma in many solid tumors. We previously isolated a novel single-chain variable fragment (scFv) 78 against TEM1 from a yeast display scFv library. Here we evaluated the potential applications of scFv78 as a tool for tumor molecular imaging, immunotoxin-based therapy and nanotherapy. Epitope mapping, three-dimensional (3D) structure docking and affinity measurements indicated that scFv78 could bind to both human and murine TEM1, with equivalent affinity, at a well-conserved conformational epitope. The rapid internalization of scFv78 and scFv78-labeled nanoparticles was triggered after specific TEM1 binding. The scFv78-saporin immunoconjugate also exerted dose-dependent cytotoxicity with high specificity to TEM1-positive cells in vitro. Finally, specific and sensitive tumor localization of scFv78 was confirmed with optical imaging in a mouse tumor model that has highly endogenous mTEM1 expression in the vasculature. Our data indicate that scFv78, the first fully human anti-TEM1 recombinant antibody, recognizes both human and mouse TEM1 and has unique and favorable features that are advantageous for the development of imaging probes or antibody-toxin conjugates for a large spectrum of human TEM1-positive solid tumors.

Cellular and functional biomarkers of clinical transplant tolerance

Development of tolerance protocols requires assays or biomarkers that distinguish tolerant recipients from non-tolerant ones to be established. In addition, a thorough understanding of the plausible mechanisms associated with clinical transplant tolerance is necessary to take the field forward. Unlike the majority of molecular signature analyses utilized by others, the emphasis of this article is on the cellular and functional biomarkers of induced transplant tolerance. Immunity to an organ transplant is very complex, comprised of two broad categories - innate and acquired or adaptive immune responses. Innate immunity can be avoided by eliminating or preventing ischemic injuries to the donor organ and tolerance at the level of adaptive immunity can be induced by infusions of a number of cellular products. Since adaptive immune response consists of inflammatory hypersensitivity, cellular (cytotoxic and helper) and humoral aspects, all these need to be measured, and the recipients who demonstrate donor-specific unresponsiveness in all can be considered tolerant or candidates for immunosuppression minimization and/or withdrawal. The mechanisms by which these agents bring about transplant tolerance include regulation, anergy, exhaustion, senescence and deletion of the recipient immune cells. Another proven mechanism of tolerance is full or mixed donor chimerism. However, it should be cautioned that non-deletional tolerance can be reversed.

Viral based vaccine TG4010 induces broadening of specific immune response and improves outcome in advanced NSCLC

BACKGROUND

Advanced non-small cell lung cancer patients receiving TG4010, a therapeutic viral vaccine encoding human Mucin 1 and interleukin-2 in addition to standard chemotherapy, displayed longer overall survival in comparison to that of patients treated with standard chemotherapy alone. Our study intended to establish the association between overall survival and vaccine-induced T cell responses against tumor associated antigens (TAA) targeted by the vaccine.

METHOD

The TIME trial was a placebo-controlled, randomized phase II study aimed at assessing efficacy of TG4010 with chemotherapy in NSCLC. 78 patients from the TIME study carrying the HLA-A02*01 haplotype were analyzed using combinatorial encoding of MHC multimers to detect low frequencies of cellular immune responses to TG4010 and other unrelated TAA.

RESULTS

We report that improvement of survival under TG4010 treatment correlated with development of T cell responses against MUC1. Interestingly, responses against MUC1 were associated with broadening of CD8 responses against non-targeted TAA, thus demonstrating induction of epitope spreading.

CONCLUSION

Our results support the causality of specific T-cell response in improved survival in NSCLC. Additionally, vaccine induced epitope spreading to other TAA participates to the enrichment of the diversity of the anti-tumor response. Hence, TG4010 appears as a useful therapeutic option to maximize response rate and clinical benefit in association with other targeted immuno-modulators.

TRIAL REGISTRATION

Registered on ClinicalTrials.gov under identifier NCT01383148 on June 23rd, 2011.

CD70 reverse signaling enhances NK cell function and immunosurveillance in CD27-expressing B-cell malignancies

CD27 expression on malignant B cells triggers CD70 reverse signaling in NK cells and improves lymphoma immunosurveillance. CD70 reverse signaling in NK cells is mediated via the AKT signaling pathway and enhances survival and effector function.

Dying cells actively regulate adaptive immune responses

Dying cells have an important role in the initiation of CD8⁺ T cell-mediated immunity. The cross-presentation of antigens derived from dying cells enables dendritic cells to present exogenous tissue-restricted or tumour-restricted proteins on MHC class I molecules. Importantly, this pathway has been implicated in multiple autoimmune diseases and accounts for the priming of tumour antigen-specific T cells. Recent data have revealed that in addition to antigen, dying cells provide inflammatory and immunogenic signals that determine the efficiency of CD8⁺ T cell cross-priming. The complexity of these signals has been evidenced by the multiple molecular pathways that result in cell death and that have now been shown to differentially influence antigen transfer and immunity. In this Review, we provide a detailed summary of both the passive and active signals that are generated by dying cells during their initiation of CD8⁺ T cell-mediated immunity. We propose that molecules generated alongside cell death pathways - inducible damage-associated molecular patterns (iDAMPs) - are upstream immunological cues that actively regulate adaptive immunity.

Characterization of the first fully human anti-TEM1 scFv in models of solid tumor imaging and immunotoxin-based therapy

Tumor endothelial marker 1 (TEM1) has been identified as a novel surface marker upregulated on the blood vessels and stroma in many solid tumors. We previously isolated a novel single-chain variable fragment (scFv) 78 against TEM1 from a yeast display scFv library. Here, we evaluated the potential applications of scFv78 as a tool for tumor molecular imaging, immunotoxin-based therapy and nanotherapy. Epitope mapping, three-dimensional structure docking and affinity measurements indicated that scFv78 could bind to both human and murine TEM1, with equivalent affinity, at a well-conserved conformational epitope. The rapid internalization of scFv78 and scFv78-labeled nanoparticles was triggered after specific TEM1 binding. The scFv78-saporin immunoconjugate also exerted dose-dependent cytotoxicity with high specificity to TEM1-positive cells in vitro. Finally, specific and sensitive tumor localization of scFv78 was confirmed with optical imaging in a tumor mouse model that has highly endogenous mTEM1 expression in the vasculature. Our data indicated that scFv78, the first fully human anti-TEM1 recombinant antibody, recognizes both human and mouse TEM1 and has unique and favorable features that are advantageous for the development of imaging probes or antibody-toxin conjugates for a large spectrum of human TEM1-positive solid tumors.

Presentation of Autoantigen in Peripheral Lymph Nodes Is Sufficient for Priming Autoreactive CD8+ T Cells

Peripheral tolerance is an important mechanism by which the immune system can guarantee a second line of defense against autoreactive T and B cells. One autoimmune disease that is related to a break of peripheral tolerance is diabetes mellitus type 1. Using the RIP-GP mouse model, we analyzed the role of the spleen and lymph nodes (LNs) in priming CD8⁺ T cells and breaking peripheral tolerance. We found that diabetes developed in splenectomized mice infected with the lymphocytic choriomeningitis virus (LCMV), a finding showing that the spleen was not necessary in generating autoimmunity. By contrast, the absence of LNs prevented the priming of LCMV-specific CD8⁺ T cells, and diabetes did not develop in these mice. Additionally, we found that dendritic cells are responsible for the distribution of virus in secondary lymphoid organs, when LCMV was administered intravenously. Preventing this distribution with the sphingosine-1-phosphate receptor antagonist FTY720 inhibits the transport of antigen to peripheral LNs and consequently prevented the onset of diabetes. However, in case of subcutaneous infection, administration of FTY720 could not inhibit the onset of diabetes because the viral antigen is already presented in the peripheral LNs. These findings demonstrate the importance of preventing the presence of antigen in LNs for maintaining tolerance.

Transfer of Allogeneic CD4+ T Cells Rescues CD8+ T Cells in Anti-PD-L1-Resistant Tumors Leading to Tumor Eradication

Adoptively transferred CD8⁺ T cells can stabilize the size of solid tumors over long periods of time by exclusively recognizing antigen cross-presented on tumor stroma. However, these tumors eventually escape T-cell-mediated growth control. The aim of this study was to eradicate such persistent cancers. In our model, the SIYRYYGL antigen is expressed by cancer cells that lack the MHC-I molecule K^b needed for direct presentation, but the antigen is picked up and cross-presented by tumor stroma. A single injection of antigen-specific 2C CD8⁺ T cells caused long-term inhibition of tumor growth, but without further intervention, tumors started to progress after approximately 3 months. Escape was associated with reduced numbers of circulating 2C cells. Tumor-infiltrating 2C cells produced significantly less TNFα and expressed more of the "exhaustion" markers PD-1 and Tim-3 than T cells from lymphoid organs. High-dose local ionizing radiation, depletion of myeloid-derived suppressor cells, infusions of additional 2C cells, and antibodies blocking PD-L1 did not prevent tumor escape. In contrast, adoptive transfer of allogeneic CD4⁺ T cells restored the numbers of circulating Ag-specific CD8⁺ T cells and their intratumoral function, resulting in tumor eradication. These CD4⁺ T cells had no antitumor effects in the absence of CD8⁺ T cells and recognized the alloantigen cross-presented on tumor stroma. CD4⁺ T cells might also be effective in cancer patients when PD-1/PD-L1 blockade does not rescue intratumoral CD8⁺ T-cell function and tumors persist. Cancer Immunol Res; 5(2); 127-36. ©2017 AACR.

Successful chemoimmunotherapy against hepatocellular cancer in a novel murine model

BACKGROUND & AIMS

We have established a clinically relevant animal model of hepatocellular cancer (HCC) in immune competent mice to elucidate the complex dialog between host immunity and tumors during HCC initiation and progression. Mechanistic findings have been leveraged to develop a clinically feasible anti-tumor chemoimmunotherapeutic strategy.

METHODS

Intraperitoneal injection of carbon tetrachloride and intrasplenic inoculation of oncogenic hepatocytes were combined to induce progressive HCCs in fibrotic livers of immunocompetent mice. Immunization and adoptive cell transfer (ACT) were used to dissect the tumor antigen-specific immune response. The ability of the tyrosine kinase inhibitor sunitinib to enhance immunotherapy in the setting of HCC was evaluated.

RESULTS

This new mouse model mimics human HCC and reflects its typical features. Tumor-antigen-specific CD8⁺ T cells maintained a naïve phenotype and remained responsive during early-stage tumor progression. Late tumor progression produced circulating tumor cells, tumor migration into draining lymph nodes, and profound exhaustion of tumor-antigen-specific CD8⁺ T cells associated with accumulation of programmed cell death protein 1 (PD-1)^hi CD8⁺ T cells and regulatory T cells (Tregs). Sunitinib-mediated tumoricidal effect and Treg suppression synergized with antibody-mediated blockade of PD-1 to powerfully suppress tumor growth and activate anti-tumor immunity.

CONCLUSION

Treg accumulation and upregulation of PD-1 provide two independent mechanisms to induce profound immune tolerance in HCC. Chemoimmunotherapy using Food and Drug Administration-approved sunitinib with anti-PD-1 antibodies achieved significant tumor control, supporting translation of this approach for the treatment of HCC patients.

LAY SUMMARY

In the current study, we have established a clinically relevant mouse model which mimics human liver cancer. Using this unique model, we studied the response of the immune system to this aggressive cancer. Findings from this trial have led to the development of an innovative and clinically feasible chemoimmunotherapeutic strategy.

Kv1.3 Channels Mark Functionally Competent CD8+ Tumor-Infiltrating Lymphocytes in Head and Neck Cancer

Tumor-infiltrating lymphocytes (TIL) are potent mediators of an antitumor response. However, their function is attenuated in solid tumors. CD8⁺ T-cell effector functions, such as cytokine and granzyme production, depend on cytoplasmic Ca²⁺, which is controlled by ion channels. In particular, Kv1.3 channels regulate the membrane potential and Ca²⁺ influx in human effector memory T (T_EM) cells. In this study, we assessed the contribution of reduced Kv1.3 and Ca²⁺ flux on TIL effector function in head and neck cancer (HNC). We obtained tumor samples and matched peripheral blood from 14 patients with HNC. CD3⁺ TILs were composed of 57% CD4⁺ (82% T_EM and 20% Tregs) and 36% CD8⁺ cells. Electrophysiology revealed a 70% reduction in functional Kv1.3 channels in TILs as compared with peripheral blood T cells from paired patients, which was accompanied by a decrease in Ca²⁺ influx. Immunofluorescence analysis showed that CD8⁺ TILs expressing high Kv1.3 preferentially localized in the stroma. Importantly, high expression of Kv1.3 correlated with high Ki-67 and granzyme B expression. Overall, these data indicate that defective Kv1.3 channels and Ca²⁺ fluxes in TILs may contribute to reduced immune surveillance in HNC. Cancer Res; 77(1); 53-61. ©2016 AACR.

Immunotherapy advances in uro-genital malignancies

Immunotherapy for the treatment of cancer has made significant progresses over the last 20 years. Multiple efforts have been attempted to restore immune-mediated tumor elimination, leading to the development of several targeted immunotherapies. Data from recent clinical trials suggest that these agents might improve the prognosis of patients with advanced genito-urinary (GU) malignancies. Nivolumab has been the first immune checkpoint-inhibitor approved for pre-treated patients with metastatic renal cell carcinoma. Pembrolizumab and atezolizumab have shown promising results in both phase I and II trials in urothelial carcinoma. Brentuximab vedotin has demonstrated early signals of clinical activity and immunomodulatory effects in highly pre-treated patients with testicular germ cell tumors. In this review, we have summarized the major clinical achievements of immunotherapy in GU cancers, focusing on immune checkpoint blockade as well as the new immunomodulatory monoclonal antibodies (mAbs) under clinical evaluation for these malignancies.

Mathematical model of tumor-immune surveillance

We present a novel mathematical model involving various immune cell populations and tumor cell populations. The model describes how tumor cells evolve and survive the brief encounter with the immune system mediated by natural killer (NK) cells and the activated CD8(+) cytotoxic T lymphocytes (CTLs). The model is composed of ordinary differential equations describing the interactions between these important immune lymphocytes and various tumor cell populations. Based on up-to-date knowledge of immune evasion and rational considerations, the model is designed to illustrate how tumors evade both arms of host immunity (i.e. innate and adaptive immunity). The model predicts that (a) an influx of an external source of NK cells might play a crucial role in enhancing NK-cell immune surveillance; (b) the host immune system alone is not fully effective against progression of tumor cells; (c) the development of immunoresistance by tumor cells is inevitable in tumor immune surveillance. Our model also supports the importance of infiltrating NK cells in tumor immune surveillance, which can be enhanced by NK cell-based immunotherapeutic approaches.

A Validated Preclinical Animal Model for Primary Bone Tumor Research

BACKGROUND

Despite the introduction of 21st-century surgical and neoadjuvant treatment modalities, survival of patients with osteosarcoma (OS) has not improved in two decades. Advances will depend in part on the development of clinically relevant and reliable animal models. This report describes the engineering and validation of a humanized tissue-engineered bone organ (hTEBO) for preclinical research on primary bone tumors in order to minimize false-positive and false-negative results due to interspecies differences in current xenograft models.

METHODS

Pelvic bone and marrow fragments were harvested from patients during reaming of the acetabulum during hip arthroplasty. HTEBOs were engineered by embedding fragments in a fibrin matrix containing bone morphogenetic protein-7 (BMP-7) and implanted into NOD-scid mice. After 10 weeks of subcutaneous growth, one group of hTEBOs was harvested to analyze the degree of humanization. A second group was injected with human luciferase-labeled OS (Luc-SAOS-2) cells. Tumor growth was followed in vivo with bioluminescence imaging. After 5 weeks, the OS tumors were harvested and analyzed. They were also compared with tumors created via intratibial injection.

RESULTS

After 10 weeks of in vivo growth, a new bone organ containing human bone matrix as well as viable and functional human hematopoietic cells developed. Five weeks after injection of Luc-SAOS-2 cells into this humanized bone microenvironment, spontaneous metastatic spread to the lung was evident. Relevant prognostic markers such as vascular endothelial growth factor (VEGF) and periostin were found to be positive in OS tumors grown within the humanized microenvironment but not in tumors created in murine tibial bones. Hypoxia-inducible transcription factor-2α (HIF-2α) was detected only in the humanized OS.

CONCLUSIONS

We report an in vivo model that contains human bone matrix and marrow components in one organ. BMP-7 made it possible to maintain viable mesenchymal and hematopoietic stem cells and created a bone microenvironment mimicking human physiology.

CLINICAL RELEVANCE

This novel platform enables preclinical research on primary bone tumors in order to test new treatment options.

Molecular and clinical implementations of ovarian cancer mouse avatar models

Innovation in oncology drug development has been hindered by lack of preclinical models that reliably predict clinical activity of novel therapies in cancer patients. Increasing desire for individualize treatment of patients with cancer has led to an increase in the use of patient-derived xenografts (PDX) engrafted into immune-compromised mice for preclinical modeling. Large numbers of tumor-specific PDX models have been established and proved to be powerful tools in pre-clinical testing. A subset of PDXs, referred to as Avatars, establish tumors in an orthotopic and treatment naïve fashion that may represent the most clinical relevant model of individual human cancers. This review will discuss ovarian cancer (OC) PDX models demonstrating the opportunities and limitations of these models in cancer drug development, and describe concepts of clinical trials design in Avatar guided therapy.

IFNγ-Dependent Interactions between ICAM-1 and LFA-1 Counteract Prostaglandin E2-Mediated Inhibition of Antitumor CTL Responses

Tumor-expressed ICAM-1 interaction with LFA-1 on naïve tumor-specific CD8(+) T cells not only stabilizes adhesion, but, in the absence of classical B7-mediated costimulation, is also able to provide potent alternative costimulatory signaling resulting in the production of antitumor cytotoxic T lymphocyte (CTL) responses. This study shows that overproduction of prostaglandin (PG) E2 by metastatic murine renal carcinoma (Renca) cells inhibited direct priming of tumor-specific CTL responses in vivo by preventing the IFNγ-dependent upregulation of ICAM-1 that is vital during the initial priming of naïve CD8(+) T cells. The addition of exogenous IFNγ during naïve CD8(+) T-cell priming abrogated PGE2-mediated suppression, and overexpression of ICAM-1 by tumor cells restored IFNγ production and proliferation among PGE2-treated tumor-specific CD8(+) T cells; preventing tumor growth in vivo These findings suggest that novel anticancer immunotherapies, which increase expression of ICAM-1 on tumor cells, could help alleviate PGE2-mediated immunosuppression of antitumor CTL responses. Cancer Immunol Res; 4(5); 400-11. ©2016 AACR.

Multifunctional nanoparticles for cancer immunotherapy

During the last decades significant progress has been made in the field of cancer immunotherapy. However, cancer vaccines have not been successful in clinical trials due to poor immunogenicity of antigen, limitations of safety associated with traditional systemic delivery as well as the complex regulation of the immune system in tumor microenvironment. In recent years, nanotechnology-based delivery systems have attracted great interest in the field of immunotherapy since they provide new opportunities to fight the cancer. In particular, for delivery of cancer vaccines, multifunctional nanoparticles present many advantages such as targeted delivery to immune cells, co-delivery of therapeutic agents, reduced adverse outcomes, blocked immune checkpoint molecules, and amplify immune activation via the use of stimuli-responsive or immunostimulatory materials. In this review article, we highlight recent progress and future promise of multifunctional nanoparticles that have been applied to enhance the efficiency of cancer vaccines.

Molecular and Translational Classifications of DAMPs in Immunogenic Cell Death

The immunogenicity of malignant cells has recently been acknowledged as a critical determinant of efficacy in cancer therapy. Thus, besides developing direct immunostimulatory regimens, including dendritic cell-based vaccines, checkpoint-blocking therapies, and adoptive T-cell transfer, researchers have started to focus on the overall immunobiology of neoplastic cells. It is now clear that cancer cells can succumb to some anticancer therapies by undergoing a peculiar form of cell death that is characterized by an increased immunogenic potential, owing to the emission of the so-called “damage-associated molecular patterns” (DAMPs). The emission of DAMPs and other immunostimulatory factors by cells succumbing to immunogenic cell death (ICD) favors the establishment of a productive interface with the immune system. This results in the elicitation of tumor-targeting immune responses associated with the elimination of residual, treatment-resistant cancer cells, as well as with the establishment of immunological memory. Although ICD has been characterized with increased precision since its discovery, several questions remain to be addressed. Here, we summarize and tabulate the main molecular, immunological, preclinical, and clinical aspects of ICD, in an attempt to capture the essence of this phenomenon, and identify future challenges for this rapidly expanding field of investigation.

Immune modulation by ER stress and inflammation in the tumor microenvironment

It is now increasingly evident that the immune system represents a barrier to tumor emergence, growth, and recurrence. Although this idea was originally proposed almost 50 years ago as the "immune surveillance hypothesis", it is commonly recognized that, with few rare exceptions, tumor cells always prevail. Thus, one of the central unsolved paradoxes of tumor immunology is how a tumor escapes immune control, which is reflected in the lack of effective autochthonous or vaccine-induced anti-tumor T cell responses. In this review, we discuss the role of the endoplasmic reticulum (ER) stress response/unfolded protein response (UPR) in the immunomodulation of myeloid cells and T cells. Specifically, we will discuss how the tumor cell UPR polarizes myeloid cells in a cell-extrinsic manner, and how in turn, thus polarized myeloid cells negatively affect T cell activation and clonal expansion.

RIPK1 and NF-κB signaling in dying cells determines cross-priming of CD8⁺ T cells

Dying cells initiate adaptive immunity by providing both antigens and inflammatory stimuli for dendritic cells, which in turn activate CD8(+) T cells through a process called antigen cross-priming. To define how different forms of programmed cell death influence immunity, we established models of necroptosis and apoptosis, in which dying cells are generated by receptor-interacting protein kinase-3 and caspase-8 dimerization, respectively. We found that the release of inflammatory mediators, such as damage-associated molecular patterns, by dying cells was not sufficient for CD8(+) T cell cross-priming. Instead, robust cross-priming required receptor-interacting protein kinase-1 (RIPK1) signaling and nuclear factor κB (NF-κB)-induced transcription within dying cells. Decoupling NF-κB signaling from necroptosis or inflammatory apoptosis reduced priming efficiency and tumor immunity. Our results reveal that coordinated inflammatory and cell death signaling pathways within dying cells orchestrate adaptive immunity.

The immunology of ablative radiation

Radiation has been a staple of cancer therapy since the early 20th century and is implemented in nearly half of current cancer treatment plans. Originally, the genotoxic function of radiation led to a focus on damage and repair pathways associated with deoxyribonucleic acid as important therapeutic targets to augment radiation efficacy. However, in recent decades, the participation of endogenous immune responses in modifying radiation effects have been widely documented and exploited in both preclinical and clinical settings. In particular, preclinical studies have highlighted the capacity of hypofractionated-radiation dose schedules to modify endogenous immune responses raising interest in the use of hypofractionation in the clinical setting to harness the indirect immune effects of radiation and improve clinical responses. We review the current literature regarding the immunomodulatory effects of hypofractionated "ablative" radiation with a primary focus on the preclinical literature but also highlight examples from the clinical literature.

Challenges and future perspectives of T cell immunotherapy in cancer

Since the formulation of the tumour immunosurveillance theory, considerable focus has been on enhancing the effectiveness of host antitumour immunity, particularly with respect to T cells. A cancer evades or alters the host immune response by various ways to ensure its development and survival. These include modifications of the immune cell metabolism and T cell signalling. An inhibitory cytokine milieu in the tumour microenvironment also leads to immune suppression and tumour progression within a host. This review traces the development in the field and attempts to summarize the hurdles that the approach of adoptive T cell immunotherapy against cancer faces, and discusses the conditions that must be improved to allow effective eradication of cancer.

Melanoma-derived factors alter the maturation and activation of differentiated tissue-resident dendritic cells

Dendritic cells (DCs) are key regulators of host immunity that are capable of inducing either immune tolerance or activation. In addition to their well-characterized role in shaping immune responses to foreign pathogens, DCs are also known to be critical for the induction and maintenance of anti-tumor immune responses. Therefore, it is important to understand how tumors influence the function of DCs and the quality of immune responses they elicit. Although the majority of studies in this field to date have utilized either immortalized DC lines or DC populations that have been generated under artificial conditions from hematopoietic precursors in vitro, we wished to investigate how tumors impact the function of already differentiated, tissue-resident DCs. Therefore, we used both an ex vivo and in vivo model system to assess the influence of melanoma-derived factors on DC maturation and activation. In ex vivo studies with freshly isolated splenic DCs, we demonstrate that the extent to which DC maturation and activation are altered by these factors correlates with melanoma tumorigenicity, and we identify partial roles for tumor-derived transforming growth factor (TGF)β1 and vascular endothelial growth factor (VEGF)-A in the altered functionality of DCs. In vivo studies using a lung metastasis model of melanoma also demonstrate tumorigenicity-dependent alterations to the function of lung-resident DCs, and skewed production of proinflammatory cytokines and chemokines by these tumor-altered cells is associated with recruitment of an immune infiltrate that may ultimately favor tumor immune escape and outgrowth.