Cold Tumors: A Therapeutic Challenge for Immunotherapy

Evolution of Molecular Targets in Melanoma Treatment

Melanoma is the deadliest type of skin cancers, accounting for more than 80% of skin cancer mortality. Although melanoma was known very early in the history of medicine, treatment for this disease had remained largely the same until very recently. Previous treatment options, including removal surgery and systemic chemotherapy, offered little benefit in extending the survival of melanoma patients. However, the last decade has seen breakthroughs in melanoma treatment, which all emerged following new insight into the oncogenic signaling of melanoma. This paper reviewed the evolution of drug targets for melanoma treatment based on the emergence of novel findings in the molecular signaling of melanoma. One of the findings that are most influential in melanoma treatment is that more than 50% of melanoma tumors contain BRAF mutations. This is fundamental for the development of BRAF inhibitors, which is the first group of drugs that significantly improves the overall survival of melanoma patients compared to the traditional chemotherapeutic dacarbazine. More recently, findings of the role of immune checkpoint molecules such as CTLA-4 and PD1/PD-L1 in melanoma biology have led to the development of a new therapeutic category: immune checkpoint inhibitors, which, for the first time in the history of cancer treatment, produced a durable response in a subset of melanoma patients. However, as this paper discussed next, there is still an unmet need for melanoma treatment. A significant population of patients did not respond to either BRAF inhibitors or immune checkpoint inhibitors. Of those patients who gained an initial response from those therapies, a remarkable percentage would develop drug resistance even when MEK inhibitors were added to the treatment. Finally, this paper discusses some possible targets for melanoma treatment.

The immune phenotype of tongue squamous cell carcinoma predicts early relapse and poor prognosis

BACKGROUND

In patients with squamous cell carcinoma of the oral tongue (OTSCC), current tumor node metastasis staging system fails to identify at-risk patients associated with early relapse and poor prognosis despite complete surgical resection. Given the importance of tumor-infiltrating lymphocytes (TILs) in the development of cancers, here we investigated the prognostic significance of the immune phenotype in OTSCC.

METHODS

Hematoxylin-eosin stained sections of OTSCCs from 211 patients were evaluated. Cancers were classified as (a) immune-inflamed when TILs were found next to tumor cell nests; (b) immune-excluded when TILs were found in the stroma, outside the tumor; and (c) immune-desert for tumors lacking lymphocyte infiltrate. The prognostic significance of these immune phenotypes classes was investigated. Data were further validated on an independent cohort from The Cancer Genome Atlas database.

RESULTS

Immune-desert phenotype was the least represented group of OTSCCs in our cohort (11.8%) and served as an independent prognostic factor. Patients with immune-desert tumors exhibited worse disease-specific survival (HR = 2.673; [CI: 95% 1.497-4.773]; P = .001), overall survival (HR = 2.591; [CI: 95% 1.468-4.572]; P = .001), and disease-free survival (HR = 2.313; [CI: 95% 1.118-4.786]; P = .024) at multivariate analysis.

CONCLUSIONS

We identified a specific subgroup of OTSCCs with poor prognosis. Tumor-infiltrating lymphocytes density and localization could serve as an integrative parameter to the current staging system and inform the selection of most appropriate treatments. In particular, the tumor immune phenotype could improve the stratification of patients with more aggressive disease.

Manipulation of immune‒vascular crosstalk: new strategies towards cancer treatment

Tumor vasculature is characterized by aberrant structure and function, resulting in immune suppressive profiles of tumor microenvironment through limiting immune cell infiltration into tumors, endogenous immune surveillance and immune cell function. Vascular normalization as a novel therapeutic strategy tends to prune some of the immature blood vessels and fortify the structure and function of the remaining vessels, thus improving immune stimulation and the efficacy of immunotherapy. Interestingly, the presence of "immune‒vascular crosstalk" enables the formation of a positive feedback loop between vascular normalization and immune reprogramming, providing the possibility to develop new cancer therapeutic strategies. The applications of nanomedicine in vascular-targeting therapy in cancer have gained increasing attention due to its specific physical and chemical properties. Here, we reviewed the recent advances of effective routes, especially nanomedicine, for normalizing tumor vasculature. We also summarized the development of enhancing nanoparticle-based anticancer drug delivery via the employment of transcytosis and mimicking immune cell extravasation. This review explores the potential to optimize nanomedicine-based therapeutic strategies as an alternative option for cancer treatment.

A new aspect of an old friend: the beneficial effect of metformin on anti-tumor immunity

T-cell-based cancer immunotherapies, such as immune checkpoint blockers (ICBs) and chimeric antigen receptor (CAR)-T-cells, have significant anti-tumor effects against certain types of cancer, providing a new paradigm for cancer treatment. However, the activity of tumor infiltrating T-cells (TILs) can be effectively neutralized in the tumor microenvironment (TME) of most solid tumors, rich in various immunosuppressive factors and cells. Therefore, to improve the clinical outcomes of established T-cell-based immunotherapy, adjuvants that can comprehensively relieve multiple immunosuppressive mechanisms of TME are needed. In this regard, recent studies have revealed that metformin has several beneficial effects on anti-tumor immunity. In this mini-review, we understand the immunosuppressive properties of TME and how metformin comprehensively enhances anti-tumor immunity. Finally, we will discuss this old friend’s potential as an adjuvant for cancer immunotherapy.

Id1 and PD-1 Combined Blockade Impairs Tumor Growth and Survival of KRAS-mutant Lung Cancer by Stimulating PD-L1 Expression and Tumor Infiltrating CD8+ T Cells

Simple Summary

Lung adenocarcinoma is the most frequent lung cancer subtype. Many of those adenocarcinomas of the lung are driven by the KRAS gene. Although immunotherapy has significantly improved the clinical outcomes of patients with lung adenocarcinomas, many patients do not benefit from that therapeutic strategy. Id1 is a protein involved in immunosuppression. Here we aimed to test whether a combined blockade of Id1 and PD-1 is able to improve outcomes of mice models with KRAS-driven lung adenocarcinoma.

Abstract

The use of PD-1/PD-L1 checkpoint inhibitors in advanced NSCLC is associated with longer survival. However, many patients do not benefit from PD-1/PD-L1 blockade, largely because of immunosuppression. New immunotherapy-based combinations are under investigation in an attempt to improve outcomes. Id1 (inhibitor of differentiation 1) is involved in immunosuppression. In this study, we explored the potential synergistic effect of the combination of Id1 inhibition and pharmacological PD-L1 blockade in three different syngeneic murine KRAS-mutant lung adenocarcinoma models. TCGA analysis demonstrated a negative and statistically significant correlation between PD-L1 and Id1 expression levels. This observation was confirmed in vitro in human and murine KRAS-driven lung cancer cell lines. In vivo experiments in KRAS-mutant syngeneic and metastatic murine lung adenocarcinoma models showed that the combined blockade targeting Id1 and PD-1 was more effective than each treatment alone in terms of tumor growth impairment and overall survival improvement. Mechanistically, multiplex quantification of CD3⁺/CD4⁺/CD8⁺ T cells and flow cytometry analysis showed that combined therapy favors tumor infiltration by CD8⁺ T cells, whilst in vivo CD8⁺ T cell depletion led to tumor growth restoration. Co-culture assays using CD8⁺ cells and tumor cells showed that T cells present a higher antitumor effect when tumor cells lack Id1 expression. These findings highlight that Id1 blockade may contribute to a significant immune enhancement of antitumor efficacy of PD-1 inhibitors by increasing PD-L1 expression and harnessing tumor infiltration of CD8⁺ T lymphocytes.

Genetically engineered macrophages persist in solid tumors and locally deliver therapeutic proteins to activate immune responses

Background

Though currently approved immunotherapies, including chimeric antigen receptor T cells and checkpoint blockade antibodies, have been successfully used to treat hematological and some solid tumor cancers, many solid tumors remain resistant to these modes of treatment. In solid tumors, the development of effective antitumor immune responses is hampered by restricted immune cell infiltration and an immunosuppressive tumor microenvironment (TME). An immunotherapy that infiltrates and persists in the solid TME, while providing local, stable levels of therapeutic to activate or reinvigorate antitumor immunity could overcome these challenges faced by current immunotherapies.

Methods

Using lentivirus-driven engineering, we programmed human and murine macrophages to express therapeutic payloads, including Interleukin (IL)-12. In vitro coculture studies were used to evaluate the effect of genetically engineered macrophages (GEMs) secreting IL-12 on T cells and on the GEMs themselves. The effects of IL-12 GEMs on gene expression profiles within the TME and tumor burden were evaluated in syngeneic mouse models of glioblastoma and melanoma and in human tumor slices isolated from patients with advanced gastrointestinal malignancies.

Results

Here, we present a cellular immunotherapy platform using lentivirus-driven genetic engineering of human and mouse macrophages to constitutively express proteins, including secreted cytokines and full-length checkpoint antibodies, as well as cytoplasmic and surface proteins that overcomes these barriers. GEMs traffic to, persist in, and express lentiviral payloads in xenograft mouse models of glioblastoma, and express a non-signaling truncated CD19 surface protein for elimination. IL-12-secreting GEMs activated T cells and induced interferon-gamma (IFNγ) in vitro and slowed tumor growth resulting in extended survival in vivo. In a syngeneic glioblastoma model, IFNγ signaling cascades were also observed in mice treated with mouse bone-marrow-derived GEMs secreting murine IL-12. These findings were reproduced in ex vivo tumor slices comprised of intact MEs. In this setting, IL-12 GEMs induced tumor cell death, chemokines and IFNγ-stimulated genes and proteins.

Conclusions

Our data demonstrate that GEMs can precisely deliver titratable doses of therapeutic proteins to the TME to improve safety, tissue penetrance, targeted delivery and pharmacokinetics.

Immunologic Characteristics of Nonmelanoma Skin Cancers: Implications for Immunotherapy

In this review, we summarize the immunology of nonmelanoma skin cancers (NMSCs) and the clinical data with immunotherapy in this heterogeneous group of cancers that include basal cell carcinoma (BCC), cutaneous squamous cell carcinoma (CSCC), and Merkel cell carcinoma (MCC). NMSCs are exceedingly common, and their treatment consumes substantial health care resources. Annual global mortality from NMSCs is comparable to that from malignant melanoma. Although the majority of NMSCs are localized at diagnosis and are treated effectively with surgery, metastases (nodal and distant) can sometimes arise and require systemic therapy. Given the success of immunotherapy in treating cutaneous melanoma, there has been an increasing interest in studying the immunology of NMSCs. Immunocompromised patients have a substantially higher risk of developing NMSCs (particularly CSCC and MCC), suggesting a role of the immune system in the pathogenesis of these cancers. Similar to cutaneous melanoma, the pathogenesis of BCC, CSCC, and virus-negative MCC is related to DNA damage from ultraviolet radiation exposure, and these cancers have a very high tumor mutational burden, which likely results in higher levels of tumor neoantigens that may be targets for the immune system. Viral antigens in virus-positive MCC are also strongly immunogenic. Emerging data from clinical trials of immune checkpoint inhibitors in NMSCs look very promising and are rapidly changing the treatment landscape of these cancers. Specifically, pembrolizumab and avelumab are U.S. Food and Drug Administration-approved for treatment of metastatic MCC and cemiplimab for metastatic CSCC. Several ongoing trials are investigating novel immunotherapies (monotherapies as well as combination) for treatment of NMSCs.

Immunostimulatory biomaterials to boost tumor immunogenicity

Cancer immunotherapy is exhibiting great promise as a new therapeutic modality for cancer treatment. However, immunotherapies are limited by the inability of some tumors to provoke an immune response. These tumors with a 'cold' immunological phenotype are characterized by low numbers of tumor-infiltrating lymphocytes, high numbers of immunosuppressive leukocytes (e.g. regulatory T cells, tumor-associated macrophages), and high production of immune-dampening signals (e.g. IL-10, TGF-β, IDO-1). Strategies to boost the aptitude of tumors to initiate an immune response (i.e. boost tumor immunogenicity) will turn 'cold' tumors 'hot' and augment the anti-tumor efficacy of current immunotherapies. Approaches to boost tumor immunogenicity already show promise; however, multifaceted delivery and immunobiology challenges exist. For instance, systemic delivery of many immune-stimulating agents causes off-target toxicity and/or the development of autoimmunity, limiting the administrable dose below the threshold needed to achieve efficacy. Moreover, once administered in vivo, molecules such as the nucleic acid-based agonists for many pattern recognition receptors are either rapidly cleared or degraded, and don't efficiently traffic to the intracellular compartments where the receptors are located. Thus, these nucleic acid-based drugs are ineffective without a delivery system. Biomaterials-based approaches aim to enhance current strategies to boost tumor immunogenicity, enable novel strategies, and spare dose-limiting toxicities. Here, we review recent progress to improve cancer immunotherapies by boosting immunogenicity within tumors using immunostimulatory biomaterials.

Chemical Strategies to Enhance the Therapeutic Efficacy of Toll-like Receptor Agonist Based Cancer Immunotherapy

Recent developments in the fields of biomedical chemistry and immune bioengineering have enabled innovative therapeutic approaches that can enhance the efficacy, accuracy, and safety of cancer immunotherapy. Among the numerous strategies utilized in cancer immunotherapy, Toll-like receptor (TLR) agonist-based approaches have been studied for a long time since they trigger the innate immune system and generate antigen-specific T cell responses to fight against tumors. In addition to these immunostimulatory functions, TLR agonists also contribute to the reprogramming of immune suppressive tumor microenvironments. Although TLR agonists are now being intensively studied in clinical trials due to their substantial immunomodulatory properties, they still show a low therapeutic index. Nonspecific and random stimulation of various immune cells produces excess levels of proinflammatory cytokines, resulting in cytokine storms and chronic diseases. Therefore, the development of chemical strategies to enhance the therapeutic efficacy as well as the safety of TLR agonist-based immunotherapy is essential and in high demand.In this Account, we summarize and discuss recent developments in biomedical chemistry and bioengineering techniques for the immunomodulation of TLR agonists that have addressed the limitations in current cancer immunotherapy. Immunomodulation of TLR agonists can be classified into two different approaches: (1) molecular modulation via chemical structure modification and (2) macroscopic modulation via an engineered drug delivery system. In molecular modulation, based on prodrug and antedrug principles, activity is modulated (active or inactive) through immolative chemical linkers that can respond to extrinsic or intrinsic biological stimulation and the plasmatic environment, respectively. To increase the effectiveness of TLR agonists as immunostimulatory agents, researchers have conjugated TLR agonists with other immunotherapeutic moieties (antigen, antibody, other TLR agonist, etc.). For macroscopic modulation, bioengineering of delivery carriers differing in size or with albumin hitchhiking moieties has been utilized to increase the efficiency of the targeting of these carriers to secondary lymphoid organs (lymph nodes (LNs) and spleen). The conjugation of specific targeting ligands and incorporation of stimulus-triggering moieties can promote the delivery of TLR agonists into specific cells or intracellular compartments. Implantable porous scaffolds for specific immune cell recruitment and in situ depot-forming gel systems for controlled release of immunomodulatory drugs can increase the therapeutic efficacy of TLR agonists while reducing systemic toxicity. Taken together, these findings show that well-designed and precisely controlled chemical strategies for the immunomodulation of TLR agonists at both the molecular and macroscopic levels are expected to play key roles in improving the therapeutic efficacy of cancer immunotherapy while minimizing immune-related toxicity.

CTNNB1 mutation suppresses infiltration of immune cells in hepatocellular carcinoma through miRNA-mediated regulation of chemokine expression

Mutations in the CTNNB1 gene in hepatocellular carcinoma (HCC) are related to immune exclusion, and HCC patients with CTNNB1 mutations tend to be primarily resistant to anti-PD1 therapy. However, systemic evaluation of immune cell infiltration in HCC with mutant CTNNB1 is lacking, and the mechanism of immune exclusion resulting from CTNNB1 mutations remains unclear. Based on CTNNB1 mutation status in HCC, we investigated RNA and miRNA expression and infiltration of immune cells. Data downloaded from TCGA showed that HCC with CTNNB1 mutation had an increased expression of CTNNB1. HCC with CTNNB1 mutation showed a reduction in infiltration score as well as in abundance of certain kinds of immune cells, including CD4 naïve T cells, CD4+ T cells, Tex cells, Th2 cells, Tfh cells, B cells, macrophages, and NK cells. Furthermore, there were 13 chemokines downregulated among all the 14 differentially expressed chemokines (DE-CKs) in CTNNB1 mutants compared to those in the wild type. A positive correlation was found between the expression of DE-CKs and infiltration score, as well as infiltration level of 6 types of immune cells, namely B cells, CD8+ cells, CD4+ cells, macrophages, neutrophils, and dendritic cells. Additionally, 302 differentially expressed immune-related genes (DE-IRGs) were involved mainly in the human immune response and cytokine-cytokine receptor interaction. The target DE-IRGs of differentially expressed miRNAs (DE-miRNAs) were identified and used to construct a network with DE-miRNAs and DE-CKs. Overall, CTNNB1 mutation in HCC led to a decrease in chemokine expression and subsequent suppression of immune cell infiltration partly through regulating specific miRNA-IRG-CK axes, pointing to a potential combination of interference of Wnt/β-catenin signaling with immunotherapy in HCC with CTNNB1 mutation.

Breast cancer-induced immune suppression in the sentinel lymph node is effectively countered by CpG-B in conjunction with inhibition of the JAK2/STAT3 pathway

BACKGROUND

We previously showed selectively hampered activation of lymph node-resident (LNR) dendritic cell (DC) subsets in the breast cancer (BrC) sentinel lymph node (SLN) to precede a state of profound T cell anergy. Reactivating these DC subsets by intratumoral delivery of the Toll-like receptor-9 (TLR9) agonist CpG-B could potentially offer a promising immune therapeutic strategy to combat this immune suppression and prevent disease spread. Unfortunately, CpG-B can limit its own immune stimulatory activity through direct TLR9-mediated activation of signal transducer and activator of transcription 3 (STAT3), pinpointed as a key regulator of immune suppression in the tumor microenvironment. Here, we have investigated whether in vitro exposure to CpG-B, with or without simultaneous inhibition of STAT3 signaling, could overcome immune suppression in BrC SLN.

METHODS

Immune modulatory effects of CpG-B (CPG7909) with or without the JAK2/STAT3 inhibitor (STAT3i) AG490 were assessed in ex vivo cultured BrC SLN-derived single-cell suspensions (N=29). Multiparameter flow cytometric analyses were conducted for DC and T cell subset characterization and assessment of (intracellular) cytokine profiles. T cell reactivity against the BrC-associated antigen Mammaglobin-A was determined by means of interferon-γ ELISPOT assay.

RESULTS

Although CpG-B alone induced activation of all DC subsets, combined inhibition of the JAK2/STAT3 pathway resulted in superior DC maturation (ie, increased CD83 expression), with most profound activation and maturation of LNR DC subsets. Furthermore, combined CpG-B and JAK2/STAT3 inhibition promoted Th1 skewing by counterbalancing the CpG-induced Th2/regulatory T cell response and significantly enhanced Mammaglobin-A specific T cell reactivity.

CONCLUSION

Ex vivo immune modulation of the SLN by CpG-B and simultaneous JAK2/STAT3 inhibition can effectively overcome BrC-induced immune suppression by preferential activation of LNR DC, ultimately restoring type 1-mediated antitumor immunity, thereby securing a BrC-specific T cell response. These findings provide a clear rationale for clinical exploration of SLN-immune potentiation through local CpG/STAT3i administration in patients with BrC.

Regulation of tumor growth by leukocyte-specific protein 1 in T cells

BACKGROUND

Clinical efficacy of T cell-based cancer immunotherapy is limited by the lack of T cell infiltration in the tumor mass, especially in solid tumors. Our group demonstrated previously that leukocyte-specific protein 1 (LSP1), an intracellular signal regulator, negatively regulates T cell infiltration in inflamed tissues.

METHODS

To determine the immuno-regulatory effects of LSP1 in T cells on tumor progression, we investigated the growth of B16 melanoma in Lsp1 knockout (KO) mice and T cell-specific Lsp1 transgenic (Tg) mice. The immune cell subpopulation infiltrated into the tumor mass as well as the expression of interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α) in T cells was assessed by flow cytometry and/or immunohistochemistry. Chemotactic migration was assayed with Lsp1 KO and Lsp1 Tg T cells. Adoptive transfer of Lsp1 KO or Lsp1 Tg T cells was performed in B16 melanoma-challenged Rag1 KO mice.

RESULTS

Lsp1 KO mice showed decreased growth of B16 melanoma and increased infiltration of T cells in the tumor mass, which were completely reversed in T cell-specific Lsp1 Tg mice. Lsp1 KO CD8⁺ T cells also exhibited elevated migratory capacity in response to CXCL9 and CXCL10, whereas Lsp1 Tg CD8⁺ T cells did the opposite. LSP1 expression was increased in tumor-infiltrating T cells and could be induced by T cell receptor activation. Intriguingly, gene expression profiling of Lsp1 KO T cells suggested enhanced cytotoxicity. Indeed, expression of IFN-γ and TNF-α was increased in tumor-infiltrating CD4⁺ and CD8⁺ T cells of Lsp1 KO mice, while it was markedly reduced in those of Lsp1 Tg mice. Adoptive transfer of Lsp1 KO T cells to Rag1 KO mice was more effective in suppressing melanoma growth than transfer of Lsp1 Tg T cells. Of note, when treated with antiprogrammed cell death protein 1 (PD-1) antibody, inhibition of melanoma growth was more pronounced in Lsp1 KO mice than in Lsp1-sufficient mice, suggesting that Lsp1 depletion additively increases the antitumor effects of anti-PD-1 antibody.

CONCLUSIONS

LSP1 in T cells regulates the growth of B16 melanoma in mice, possibly by affecting migration and infiltration of T cells into the tumor and by modulating production of antitumor effector cytokines by CD8⁺ T cells. These findings provide evidence that LSP1 can be a target to improve the efficacy of T cell-based immunotherapy.

Dendritic Cell and T Cell Crosstalk in Liver Fibrogenesis and Hepatocarcinogenesis: Implications for Prevention and Therapy of Liver Cancer

Liver fibrosis is a chronic, highly prevalent disease that may progress to cirrhosis and substantially increases the risk for development of hepatocellular carcinoma (HCC). Fibrotic livers are characterized by an inflammatory microenvironment that is composed of various immunologically active cells, including liver-resident populations (e.g., Kupffer cells, hepatic stellate cells and sinusoidal endothelium) and infiltrating leukocytes (e.g., monocytes, monocyte-derived macrophages, neutrophils and lymphocytes). While inflammatory injury drives both fibrogenesis and carcinogenesis, the tolerogenic microenvironment of the liver conveys immunosuppressive effects that encourage tumor growth. An insufficient crosstalk between dendritic cells (DCs), the professional antigen presenting cells, and T cells, the efficient anti-tumor effector cells, is one of the main mechanisms of HCC tumor tolerance. The meticulous analysis of patient samples and mouse models of fibrosis-HCC provided in-depth insights into molecular mechanisms of immune interactions in liver cancer. The therapeutic modulation of this multifaceted immunological response, e.g., by inhibiting immune checkpoint molecules, in situ vaccination, oncolytic viruses or combinations thereof, is a rapidly evolving field that holds the potential to improve the outcome of patients with HCC. This review aims to highlight the current understanding of DC–T cell interactions in fibrogenesis and hepatocarcinogenesis and to illustrate the potentials and pitfalls of therapeutic clinical translation.

T-cell agonists in cancer immunotherapy

Cancer cells can evade immune surveillance in the body. However, immune checkpoint inhibitors can interrupt this evasion and enhance the antitumor activity of T cells. Other mechanisms for promoting antitumor T-cell function are the targeting of costimulatory molecules expressed on the surface of T cells, such as 4-1BB, OX40, inducible T-cell costimulator and glucocorticoid-induced tumor necrosis factor receptor. In addition, CD40 targets the modulation of the activation of antigen-presenting cells, which ultimately leads to T-cell activation. Agonists of these costimulatory molecules have demonstrated promising results in preclinical and early-phase trials and are now being tested in ongoing clinical trials. In addition, researchers are conducting trials of combinations of such immune modulators with checkpoint blockade, radiotherapy and cytotoxic chemotherapeutic drugs in patients with advanced tumors. This review gives a comprehensive picture of the current knowledge of T-cell agonists based on their use in recent and ongoing clinical trials.

Polymer-loaded hydrogels serve as depots for lactate and mimic "cold" tumor microenvironments

The burgeoning field of biomaterials for immunotherapy has aided in the understanding of foundational mechanisms of cancer immunology. In particular, implantable biomaterials can be engineered to investigate specific aspects of the tumor microenvironment either singularly or in combination. Of note, the metabolite - lactate, a byproduct of anaerobic glycolysis, is known to reprogram immune cells, resulting in increased tumor survival. An adequate model that can recapitulate intratumoral lactate concentrations does not exist. In this study, we demonstrate that a simple biomaterial platform could be developed as an instructive tool to decipher the effects of lactate in vivo. Briefly, we demonstrate that a peptide hydrogel loaded with granulocyte-macrophage colony stimulating factor and poly-(lactic-co-glycolic acid)/(lactic acid) microparticles can generate the localized lactate concentrations (∼2-22 mM) and cellular makeup of the tumor microenvironment, following subcutaneous implantation in mice. Furthermore, infiltrating immune cells adopt phenotypes similar to those seen in other in vitro and in vivo cancer models, including immunosupressive dendritic cells. This hydrogel system is a framework to interrogate immune cell modulation in cancer-like environments using safe and degradable biomaterials. Moreover, this system can be multifaceted, as incorporation of other cancer tumor environmental factors or chemotherapeutic drugs is facile and could be insightful in developing or improving immunotherapies.

Hybrid Fc-fused interleukin-7 induces an inflamed tumor microenvironment and improves the efficacy of cancer immunotherapy

Objectives

Emerging oncotherapeutic strategies require the induction of an immunostimulatory tumor microenvironment (TME) containing numerous tumor‐reactive CD8⁺ T cells. Interleukin‐7 (IL‐7), a T‐cell homeostatic cytokine, induces an antitumor response; however, the detailed mechanisms underlying the contributions of the IL‐7 to TME remain unclear. Here, we aimed to investigate the mechanism underlying the induction of antitumor response by hybrid Fc‐fused long‐acting recombinant human IL‐7 (rhIL‐7‐hyFc) through regulation of both adaptive and innate immune cells in the TME.

Methods

We evaluated rhIL‐7‐hyFc‐mediated antitumor responses in murine syngeneic tumor models. We analysed the cellular and molecular features of tumor‐infiltrating lymphocytes (TILs) and changes in the TME after rhIL‐7‐hyFc treatment. Furthermore, we evaluated the antitumor efficacy of rhIL‐7‐hyFc combined with chemotherapy and checkpoint inhibitors (CPIs).

Results

Systemic delivery of rhIL‐7‐hyFc induced significant therapeutic benefits by expanding CD8⁺ T cells with enhanced tumor tropism. In tumors, rhIL‐7‐hyFc increased both tumor‐reactive and bystander CD8⁺ TILs, all of which displayed enhanced effector functions but less exhausted phenotypes. Moreover, rhIL‐7‐hyFc suppressed the generation of immunosuppressive myeloid cells in the bone marrow of tumor‐bearing mice, resulting in the immunostimulatory TME. Combination therapy with chemotherapy and CPIs, rhIL‐7‐hyFc elicited a strong antitumor response and even under a T lymphopenic condition by restoring CD8⁺ T cells. When combined with chemotherapy and CPIs, rhIL‐7‐hyFc administration enhanced antitumor response under intact andlymphopenic conditions by restoring CD8⁺ T cells.

Conclusion

Taken together, these data demonstrate that rhIL‐7‐hyFc induces antitumor responses by generating T‐cell‐inflamed TME and provide a preclinical proof of concept of immunotherapy with rhIL‐7‐hyFc to enhance therapeutic responses in the clinic.

Tailoring precision immunotherapy: coming to a clinic soon?

Cell-based and antibody-based cancer immunotherapies have been widely tested across increasing numbers of cancers with an unprecedented number of successful practice-changing immunotherapy clinical trials, achieving significant survival outcomes and, characteristically, some very long-term survivors. Still, a sizeable proportion of patients, especially with solid tumours, do not benefit from immunotherapy. Here, we summarise key literature on immunotherapy biomarkers and resistance mechanisms and discuss potential strategies to overcome such resistance to improve patient outcomes. The ever-expanding understanding of the tumour-immune interaction and the tumour microenvironment allows a real opportunity to identify predictive biomarkers and tailor immune-based therapies, including designing rational combination drugs to enhance clinical outcomes, and to identify patients most likely to benefit from immunotherapy. Where there has never been a precision chemotherapy clinic in the last 70 years since its inception, even with no shortage of trying, the hope and evolution of a functional precision immunotherapy cancer clinic is a much more likely reality.

The VE-Cadherin/β-catenin signalling axis regulates immune cell infiltration into tumours

Vascular normalisation, the process that reverses the structural and functional abnormalities seen in tumour-associated vessels, is also accompanied by changes in leucocyte trafficking. Our previous studies have shown the normalisation effects of the agent CD5-2 which acts to stabilise VE-Cadherin leading to increased penetration of CD8⁺ T cells but decreased infiltration of neutrophils (CD11b⁺Gr1^hi) into tumour parenchyma. In the present study, we demonstrate that VE-Cadherin stabilisation through CD5-2 treatment of purified endothelial cells (ECs) results in a similar leucocyte-selective regulation of transmigration, suggesting the existence of an endothelial specific intrinsic mechanism. Further, we show by RNA sequencing (RNA-seq)-based transcriptomic analysis, that treatment of ECs with CD5-2 regulates chemokines known to be involved in leucocyte transmigration, including upregulation of CCL2 and CXCL10 that facilitate CD8⁺ T cell transmigration. Both in vitro and in vivo mechanistic studies revealed that the increased CCL2 expression was dependent on expression of VE-Cadherin and downstream activation of the AKT/GSK3β/β-catenin/TCF4 signalling pathway. CD5-2 treatment also contributed to the reorganisation of the cytoskeleton, inducing reorganisation of stress fibres to circumferential actin, which previously has been described as associated with the stabilisation of the endothelial barrier, and amplification of the transcellular migration of CD8⁺ T cells. Thus, we propose that promotion of endothelial junctional integrity during vascular normalisation not only inhibits vascular leak but also resets the endothelial dependent regulation of immune cell infiltration.

Differential gene expression of tumor-infiltrating CD8+ T cells in advanced versus early-stage colorectal cancer and identification of a gene signature of poor prognosis

Background

Cytotoxic CD8⁺ T cell-mediated response is the most important arm of adaptive immunity, which dictates the capacity of the host immune response in eradicating tumor cells. Due to tumor intrinsic and/or extrinsic factors, the density and function of CD8⁺ tumor-infiltrating lymphocytes (TILs) could be compromised, leading to poor prognosis and survival.

Methods

Using RNA-Seq, transcriptomes of sorted CD3⁺CD8⁺ TILs from treatment-naïve colorectal cancer (CRC) patients at advanced stages (III and IV) were compared with those from patients with early stages (I and II). A signature referred to as ‘poor prognosis CD8 gene signature (ppCD8sig)’ was identified and analyzed in The Cancer Genome Atlas CRC dataset. Scores for the ppCD8sig were calculated and classified as high, intermediate and low, and its prognostic significance was assessed using multivariate analysis and Cox proportional hazard model. Densities of CD3⁺ and CD8⁺ T cell infiltration in tumors from patients with high and low ppCD8sig scores were assessed by flow cytometry and immunostaining.

Results

Genes related to epigenetic regulation and response to hypoxia were upregulated in CD8⁺ TILs from patients with advanced stages, while genes related to T cell activation, cell proliferation and cell cycle were downregulated. Patients with high ppCD8sig score had poorer disease-specific survival (DSS) and shorter progression-free interval (PFI). The ppCD8sig was an independent prognostic indicator for DSS (HR 1.83, 95% CI 1.40 to 2.38, p<0.0001) and PFI (HR 1.42, 95% CI 1.04 to 1.93, p=0.026). Additionally, patients with high ppCD8sig score were more likely to have advanced stages (χ² p<0.0001) and residual disease after primary therapy (χ² p=0.046). Patients with high ppCD8sig score had reduced levels of CD3⁺ and CD8⁺ TILs and low Immunoscores (IS), compared to patients with low ppCD8sig score.

Conclusions

Our data provided insights into the altered regulation of biological mechanisms and signaling pathways in CD8⁺ TILs during CRC progression, and revealed a gene signature as an independent prognostic indicator. Patients with high ppCD8sig score had lower levels of TILs and low IS. These data further confirm the prognostic value of the identified ppCD8sig and potentially highlight its clinical relevance.

Putting into Perspective the Future of Cancer Vaccines: Targeted Immunotherapy

Pre-clinical models and human clinical trials have confirmed the ability of cancer vaccines to induce immune responses that are tumour-specific and, in some cases, associated with clinical response. However, cancer vaccines as a targeted immunotherapy strategy have not yet come of age. So, why the discordance after so much research has been invested in cancer vaccines? There are several reasons for this that include: limited tumour immunogenicity (limited targeted antigen expression, antigen tolerance); antigenic heterogeneity in tumours; heterogeneity of individual immune responses; multiple mechanisms associated with suppressed functional activity of immune effector cells, the underlying rationale for the use of immune checkpoint inhibitors; and immune system exhaustion. The success of checkpoint therapy has refocussed investigations into defining relationships between tumours and host immune systems, appreciating the mechanisms by which tumour cells escape immune surveillance and reinforcing recognition of the potential of vaccines in the treatment and prevention of cancer. Recent developments in cancer immunotherapies, together with associated technologies, for instance, the unparalleled achievements by immune checkpoint inhibitors and neo-antigen identification tools, may foster potential improvements in cancer vaccines for the treatment of malignancies.

Pharmacologic Suppression of B7-H4 Glycosylation Restores Antitumor Immunity in Immune-Cold Breast Cancers

Despite widespread utilization of immunotherapy, treating immune-cold tumors has proved to be a challenge. Here, we report that expression of the immune checkpoint molecule B7-H4 is prevalent among immune-cold triple-negative breast cancers (TNBC), where its expression inversely correlates with that of PD-L1. Glycosylation of B7-H4 interferes with its interaction/ubiquitination by AMFR, resulting in B7-H4 stabilization. B7-H4 expression inhibits doxorubicin-induced cell death through the suppression of eIF2α phosphorylation required for calreticulin exposure vis-à-vis the cancer cells. NGI-1, which inhibits B7-H4 glycosylation causing its ubiquitination and subsequent degradation, improves the immunogenic properties of cancer cells treated with doxorubicin, enhancing their phagocytosis by dendritic cells and their capacity to elicit CD8⁺ IFNγ-producing T-cell responses. In preclinical models of TNBC, a triple combination of NGI-1, camsirubicin (a noncardiotoxic doxorubicin analogue) and PD-L1 blockade was effective in reducing tumor growth. Collectively, our findings uncover a strategy for targeting the immunosuppressive molecule B7-H4. SIGNIFICANCE: This work unravels the regulation of B7-H4 stability by ubiquitination and glycosylation, which affects tumor immunogenicity, particularly regarding immune-cold breast cancers. The inhibition of B7-H4 glycosylation can be favorably combined with immunogenic chemotherapy and PD-L1 blockade to achieve superior immuno-infiltration of cold tumors, as well as improved tumor growth control.See related commentary by Pearce and Läubli, p. 1789.This article is highlighted in the In This Issue feature, p. 1775.

CRISPR-Cas, a robust gene-editing technology in the era of modern cancer immunotherapy

Cancer immunotherapy has been emerged as a promising strategy for treatment of a broad spectrum of malignancies ranging from hematological to solid tumors. One of the principal approaches of cancer immunotherapy is transfer of natural or engineered tumor-specific T-cells into patients, a so called "adoptive cell transfer", or ACT, process. Construction of allogeneic T-cells is dependent on the employment of a gene-editing tool to modify donor-extracted T-cells and prepare them to specifically act against tumor cells with enhanced function and durability and least side-effects. In this context, CRISPR technology can be used to produce universal T-cells, equipped with recombinant T cell receptor (TCR) or chimeric antigen receptor (CAR), through multiplex genome engineering using Cas nucleases. The robust potential of CRISPR-Cas in preparing the building blocks of ACT immunotherapy has broaden the application of such therapies and some of them have gotten FDA approvals. Here, we have collected the last investigations in the field of immuno-oncology conducted in partnership with CRISPR technology. In addition, studies that have addressed the challenges in the path of CRISPR-mediated cancer immunotherapy, as well as pre-treatment applications of CRISPR-Cas have been mentioned in detail.

Breaking Bottlenecks for the TCR Therapy of Cancer

Immune checkpoint inhibitors have redefined the treatment of cancer, but their efficacy depends critically on the presence of sufficient tumor-specific lymphocytes, and cellular immunotherapies develop rapidly to fill this gap. The paucity of suitable extracellular and tumor-associated antigens in solid cancers necessitates the use of neoantigen-directed T-cell-receptor (TCR)-engineered cells, while prevention of tumor evasion requires combined targeting of multiple neoepitopes. These can be currently identified within 2 weeks by combining cutting-edge next-generation sequencing with bioinformatic pipelines and used to select tumor-reactive TCRs in a high-throughput manner for expeditious scalable non-viral gene editing of autologous or allogeneic lymphocytes. "Young" cells with a naive, memory stem or central memory phenotype can be additionally armored with "next-generation" features against exhaustion and the immunosuppressive tumor microenvironment, where they wander after reinfusion to attack heavily pretreated and hitherto hopeless neoplasms. Facilitated by major technological breakthroughs in critical manufacturing steps, based on a solid preclinical rationale, and backed by rapidly accumulating evidence, TCR therapies break one bottleneck after the other and hold the promise to become the next immuno-oncological revolution.

Enhancing the efficacy of immunotherapy using radiotherapy

Recent clinical breakthroughs in cancer immunotherapy, especially with immune checkpoint blockade, offer great hope for cancer sufferers - and have greatly changed the landscape of cancer treatment. However, whilst many patients achieve clinical responses, others experience minimal benefit or do not respond to immune checkpoint blockade at all. Researchers are therefore exploring multimodal approaches by combining immune checkpoint blockade with conventional cancer therapies to enhance the efficacy of treatment. A growing body of evidence from both preclinical studies and clinical observations indicates that radiotherapy could be a powerful driver to augment the efficacy of immune checkpoint blockade, because of its ability to activate the antitumor immune response and potentially overcome resistance. In this review, we describe how radiotherapy induces DNA damage and apoptosis, generates immunogenic cell death and alters the characteristics of key immune cells in the tumor microenvironment. We also discuss recent preclinical work and clinical trials combining radiotherapy and immune checkpoint blockade in thoracic and other cancers. Finally, we discuss the scheduling of immune checkpoint blockade and radiotherapy, biomarkers predicting responses to combination therapy, and how these novel data may be translated into the clinic.

Tackling Resistance to Cancer Immunotherapy: What Do We Know?

Cancer treatment has evolved tremendously in the last few decades. Immunotherapy has been considered to be the forth pillar in cancer treatment in addition to conventional surgery, radiotherapy, and chemotherapy. Though immunotherapy has resulted in impressive response, it is generally limited to a small subset of patients. Understanding the mechanisms of resistance toward cancer immunotherapy may shed new light to counter that resistance. In this review, we highlighted and summarized two major hurdles (recognition and attack) of cancer elimination by the immune system. The mechanisms of failure of some available immunotherapy strategies were also described. Moreover, the significance role of immune compartment for various established cancer treatments were also elucidated in this review. Then, the mechanisms of combinatorial treatment of various conventional cancer treatment with immunotherapy were discussed. Finally, a strategy to improve immune cancer killing by characterizing cancer immune landscape, then devising treatment based on that cancer immune landscape was put forward.

Epigenetics in modulating immune functions of stromal and immune cells in the tumor microenvironment

Epigenetic regulation of gene expression in cancer cells has been extensively studied in recent decades, resulting in the FDA approval of multiple epigenetic agents for treating different cancer types. Recent studies have revealed novel roles of epigenetic dysregulation in altering the phenotypes of immune cells and tumor-associated stromal cells, including fibroblasts and endothelial cells. As a result, epigenetic dysregulation of these cells reshapes the tumor microenvironment (TME), changing it from an antitumor environment to an immunosuppressive environment. Here, we review recent studies demonstrating how specific epigenetic mechanisms drive aspects of stromal and immune cell differentiation with implications for the development of solid tumor therapeutics, focusing on the pancreatic ductal adenocarcinoma (PDA) TME as a representative of solid tumors. Due to their unique ability to reprogram the TME into a more immunopermissive environment, epigenetic agents have great potential for sensitizing cancer immunotherapy to augment the antitumor response, as an immunopermissive TME is a prerequisite for the success of cancer immunotherapy but is often not developed with solid tumors. The idea of combining epigenetic agents with cancer immunotherapy has been tested both in preclinical settings and in multiple clinical trials. In this review, we highlight the basic biological mechanisms underlying the synergy between epigenetic therapy and immunotherapy and discuss current efforts to translate this knowledge into clinical benefits for patients.

Tumour vasculature: Friend or foe of oncolytic viruses?

In the past two decades there have been substantial advances in understanding the anti-cancer mechanisms of oncolytic viruses (OVs). OVs can mediate their effects directly, by preferentially infecting and killing tumour cells. Additionally, OVs can indirectly generate anti-tumour immune responses. These differing mechanisms have led to a paradoxical divergence in strategies employed to further increase the potency of oncolytic virotherapies. On one hand, the tumour neovasculature is seen as a vital lifeline to the survival of the tumour, leading some to use OVs to target the tumour vasculature in hopes to starve cancers. Therapeutics causing vascular collapse can potentiate tumour hypoxia, nutrient restriction and pro-inflammatory cytokine release, which has shown promise in oncological studies. On the other hand, the same vasculature plays an important role for the dissemination of OVs, trafficking of effector cells and other therapeutics, which has prompted researchers to find ways of normalizing the vasculature to enhance infiltration of leukocytes and delivery of therapeutic agents. This article describes the recent developments of therapies aimed to shut down versus normalize tumour vasculature in order to inform researchers striving to optimize OV-based therapies.

Cancer immunotherapy with γδ T cells: many paths ahead of us

γδ T cells play uniquely important roles in stress surveillance and immunity for infections and carcinogenesis. Human γδ T cells recognize and kill transformed cells independently of human leukocyte antigen (HLA) restriction, which is an essential feature of conventional αβ T cells. Vγ9Vδ2 γδ T cells, which prevail in the peripheral blood of healthy adults, are activated by microbial or endogenous tumor-derived pyrophosphates by a mechanism dependent on butyrophilin molecules. γδ T cells expressing other T cell receptor variable genes, notably Vδ1, are more abundant in mucosal tissue. In addition to the T cell receptor, γδ T cells usually express activating natural killer (NK) receptors, such as NKp30, NKp44, or NKG2D which binds to stress-inducible surface molecules that are absent on healthy cells but are frequently expressed on malignant cells. Therefore, γδ T cells are endowed with at least two independent recognition systems to sense tumor cells and to initiate anticancer effector mechanisms, including cytokine production and cytotoxicity. In view of their HLA-independent potent antitumor activity, there has been increasing interest in translating the unique potential of γδ T cells into innovative cellular cancer immunotherapies. Here, we discuss recent developments to enhance the efficacy of γδ T cell-based immunotherapy. This includes strategies for in vivo activation and tumor-targeting of γδ T cells, the optimization of in vitro expansion protocols, and the development of gene-modified γδ T cells. It is equally important to consider potential synergisms with other therapeutic strategies, notably checkpoint inhibitors, chemotherapy, or the (local) activation of innate immunity.

The updated landscape of tumor microenvironment and drug repurposing

Accumulating evidence shows that cellular and acellular components in tumor microenvironment (TME) can reprogram tumor initiation, growth, invasion, metastasis, and response to therapies. Cancer research and treatment have switched from a cancer-centric model to a TME-centric one, considering the increasing significance of TME in cancer biology. Nonetheless, the clinical efficacy of therapeutic strategies targeting TME, especially the specific cells or pathways of TME, remains unsatisfactory. Classifying the chemopathological characteristics of TME and crosstalk among one another can greatly benefit further studies exploring effective treating methods. Herein, we present an updated image of TME with emphasis on hypoxic niche, immune microenvironment, metabolism microenvironment, acidic niche, innervated niche, and mechanical microenvironment. We then summarize conventional drugs including aspirin, celecoxib, β-adrenergic antagonist, metformin, and statin in new antitumor application. These drugs are considered as viable candidates for combination therapy due to their antitumor activity and extensive use in clinical practice. We also provide our outlook on directions and potential applications of TME theory. This review depicts a comprehensive and vivid landscape of TME from biology to treatment.

Genomic Mapping Identifies Mutations in RYR2 and AHNAK as Associated with Favorable Outcome in Basal-Like Breast Tumors Expressing PD1/PD-L1

Treatment with anti-PD-L1 antibodies has shown efficacy in basal-like breast cancer. In this context, identification of pre-activated immune tumors is a main goal. Here we explore mutations in PD1 and PD-L1 high-expressing tumors to identify genomic correlates associated with outcome. To do so, RNA-seq and mutation data from 971 breast cancer patients from the TCGA dataset were used to identify most prevalent mutations in patients with high levels of PD1 and PD-L1. Transcriptomic signatures associated with the selected mutations were identified and analyzed in terms of outcome and immune cell infiltration. We identified co-occurrent mutations in RYR2 and AHNAK in 8% and 5% of basal-like tumors respectively, which conferred good prognosis in patients with high expression of PD1 and PD-L1 genes. The transcriptomic signature associated with these mutations, composed of CXCL9, GBP5, C1QA, IL2RG, CSF2RB, IDO1 and LAG3 genes, also conferred good prognosis and correlated with immune infiltrations within the tumors. The joint signature classified patients with favorable relapse-free survival (HR: 0.28; CI: 0.2–0.38; p = 1.7 × 10⁻¹⁶) and overall survival (HR: 0.18; CI: 0.09–0.34; p = 6.8 × 10⁻⁹), showing a stronger prediction capacity than previous reported signatures. In conclusion, we describe two novel mutations and their transcriptomic signature, both associated with a favorable outcome and immune infiltrates in PD1 and PD-L1 high-expressing basal-like tumors.

New Approaches on Cancer Immunotherapy

Metastasis, which occurs when cancer cells disseminate from the primary tumor site to other parts of the body, is the primary cause of mortality in patients, and the recurrence of multiple metastatic tumors is an obstacle to eliminating cancer. Recent clinical studies demonstrated that patients who respond to immunotherapy have longer survival rates with lower metastatic relapse, suggesting that immunotherapy may be one of the solutions to overcome cancer metastasis. Indeed, various host immune cells not only shape the tumor microenvironment but also participate in multiple stages of metastasis. Therefore, to improve clinical outcome, it is critical to understand the immunological events associated with tumor development and progression. In this article, we summarize those events that are involved in tumor progression and discuss immunotherapies that can potentially target cancer metastasis.

Comprehensive analyses of immunodynamics and immunoreactivity in response to treatment in ALK-positive non-small-cell lung cancer

Background

EML4-ALK is a distinct molecular entity that is highly sensitive to ALK tyrosine kinase inhibitors (TKIs). Immune checkpoint inhibitors (ICIs) have not proved efficacy in ALK-positive non-small cell lung cancer so far. In this study, we performed a mouse clinical trial using EML4-ALK transgenic mice model to comprehensively investigate immunomodulatory effects of ALK TKI and to investigate the mechanisms of resistance to ICIs.

Methods

EML4-ALK transgenic mice were randomized to three treatment arms (arm A: antiprogrammed death cell protein-1 (PD-1), arm B: ceritinib, arm C: anti-PD-1 and ceritinib), and tumor response was evaluated using MRI. Progression-free survival and overall survival were measured to compare the efficacy. Flow cytometry, multispectral imaging, whole exome sequencing and RNA sequencing were performed from tumors obtained before and after drug resistance.

Results

Mouse clinical trial revealed that anti-PD-1 therapy was ineffective, and the efficacy of ceritinib and anti-PD-1 combination was not more effective than ceritinib alone in the first line. Dynamic changes in immune cells and cytokines were observed following each treatment, while changes in T lymphocytes were not prominent. A closer look at the tumor immune microenvironment before and after ceritinib resistance revealed increased regulatory T cells and programmed death-ligand 1 (PD-L1)-expressing cells both in the tumor and the stroma. Despite the increase of PD-L1 expression, these findings were not accompanied by increased effector T cells which mediate antitumor immune responses.

Conclusions

ALK-positive tumors progressing on ceritinib is not immunogenic enough to respond to immune checkpoint inhibitors.

Immune cells as tumor drug delivery vehicles

This review article describes the use of immune cells as potential candidates to deliver anti-cancer drugs deep within the tumor microenvironment. First, the rationale of using drug carriers to target tumors and potentially decrease drug-related side effects is discussed. We further explain some of the current limitations when using nanoparticles for this purpose. Next, a comprehensive step-by-step description of the migration cascade of immune cells is provided as well as arguments on why immune cells can be used to address some of the limitations associated with nanoparticle-mediated drug delivery. We then describe the benefits and drawbacks of using red blood cells, platelets, granulocytes, monocytes, macrophages, myeloid-derived suppressor cells, T cells and NK cells for tumor-targeted drug delivery. An additional section discusses the versatility of nanoparticles to load anti-cancer drugs into immune cells. Lastly, we propose increasing the circulatory half-life and development of conditional release strategies as the two main future pillars to improve the efficacy of immune cell-mediated drug delivery to tumors.

Innate Immune Defense Mechanisms by Myeloid Cells That Hamper Cancer Immunotherapy

Over the past decade, cancer immunotherapy has been steering immune responses toward cancer cell eradication. However, these immunotherapeutic approaches are hampered by the tumor-promoting nature of myeloid cells, including monocytes, macrophages, and neutrophils. Despite the arsenal of defense strategies against foreign invaders, myeloid cells succumb to the instructions of an established tumor. Interestingly, the most primordial defense responses employed by myeloid cells against pathogens, such as complement activation, antibody-dependent cell cytotoxicity and phagocytosis, actually seem to favor cancer progression. In this review, we discuss how rudimentary defense mechanisms deployed by myeloid cells can promote tumor progression.

Medical Treatment of Lung Cancer: Can Immune Cells Predict the Response? A Systematic Review

The landscape for medical treatment of lung cancer has irreversibly changed since the development of immuno-oncology (IO). Yet, while immune checkpoint blockade (ICB) revealed that T lymphocytes play a major role in lung cancer, the precise dynamic of innate and adaptive immune cells induced by anticancer treatments including chemotherapy, targeted therapy, and/or ICB is poorly understood. In lung cancer, studies evaluating specific immune cell populations as predictors of response to medical treatment are scarce, and knowledge is fragmented. Here, we review the different techniques allowing the detection of immune cells in the tumor and blood (multiplex immunohistochemistry and immunofluorescence, RNA-seq, DNA methylation pattern, mass cytometry, functional tests). In addition, we present data that consider different baseline immune cell populations as predictors of response to medical treatments of lung cancer. We also review the potential for assessing dynamic changes in cell populations during treatment as a biomarker. As powerful tools for immune cell detection and data analysis are available, clinicians and researchers could increase understanding of mechanisms of efficacy and resistance in addition to identifying new targets for IO by developing translational studies that decipher the role of different immune cell populations during lung cancer treatments.

Focused Ultrasound Stimulates ER Localized Mechanosensitive PANNEXIN-1 to Mediate Intracellular Calcium Release in Invasive Cancer Cells

Focused ultrasound (FUS) is a rapidly developing stimulus technology with the potential to uncover novel mechanosensory dependent cellular processes. Since it is non-invasive, it holds great promise for future therapeutic applications in patients used either alone or as a complement to boost existing treatments. For example, FUS stimulation causes invasive but not non-invasive cancer cell lines to exhibit marked activation of calcium signaling pathways. Here, we identify the membrane channel PANNEXIN1 (PANX1) as a mediator for activation of calcium signaling in invasive cancer cells. Knockdown of PANX1 decreases calcium signaling in invasive cells, while PANX1 overexpression enhances calcium elevations in non-invasive cancer cells. We demonstrate that FUS may directly stimulate mechanosensory PANX1 localized in endoplasmic reticulum to evoke calcium release from internal stores. This process does not depend on mechanosensory stimulus transduction through an intact cytoskeleton and does not depend on plasma membrane localized PANX1. Plasma membrane localized PANX1, however, plays a different role in mediating the spread of intercellular calcium waves via ATP release. Additionally, we show that FUS stimulation evokes cytokine/chemokine release from invasive cancer cells, suggesting that FUS could be an important new adjuvant treatment to improve cancer immunotherapy.

Uncovering the Tumor Antigen Landscape: What to Know about the Discovery Process

According to the latest available data, cancer is the second leading cause of death, highlighting the need for novel cancer therapeutic approaches. In this context, immunotherapy is emerging as a reliable first-line treatment for many cancers, particularly metastatic melanoma. Indeed, cancer immunotherapy has attracted great interest following the recent clinical approval of antibodies targeting immune checkpoint molecules, such as PD-1, PD-L1, and CTLA-4, that release the brakes of the immune system, thus reviving a field otherwise poorly explored. Cancer immunotherapy mainly relies on the generation and stimulation of cytotoxic CD8 T lymphocytes (CTLs) within the tumor microenvironment (TME), priming T cells and establishing efficient and durable anti-tumor immunity. Therefore, there is a clear need to define and identify immunogenic T cell epitopes to use in therapeutic cancer vaccines. Naturally presented antigens in the human leucocyte antigen-1 (HLA-I) complex on the tumor surface are the main protagonists in evocating a specific anti-tumor CD8+ T cell response. However, the methodologies for their identification have been a major bottleneck for their reliable characterization. Consequently, the field of antigen discovery has yet to improve. The current review is intended to define what are today known as tumor antigens, with a main focus on CTL antigenic peptides. We also review the techniques developed and employed to date for antigen discovery, exploring both the direct elution of HLA-I peptides and the in silico prediction of epitopes. Finally, the last part of the review analyses the future challenges and direction of the antigen discovery field.

Clinical relevance of B7H3 expression in retinoblastoma

Retinoblastoma (RB) is the most common paediatric intraocular tumour. Currently, chemotherapy is widely used to reduce the chance of metastasis as well as for vision salvage. The limitations of chemotherapy for RB include chemoresistance and cytotoxicity. Recently, immunotherapy is considered for treating chemoresistant cancers. Although, several molecular targets are available for immunotherapy in different cancers, we were interested in B7H3, as it was differentially expressed between retinoblastoma and retina in our earlier proteomics study. Hence, in this study we validated the previous finding by Western blotting and immunohistochemistry on primary RB tumor samples. The results suggest significantly increased expression of B7H3 in RB tumor samples compared to retina by western blotting. Immunohistochemistry revealed spatial, inter and intratumoral heterogeneity in the primary RB tumor sections. Correlation of the B7H3 expression with clinical and histopathological data revealed significantly increased expression of B7H3 in poorly differentiated, non-neural invasive tumors and lower expression in neural invasion and severe anaplastic areas of the tumors. B7H3 expression did not significantly vary between low-risk and high-risk tumors. The study also revealed considerably reduced infiltration of T lymphocytes in RB. We conclude that B7H3 is prominently expressed in primary RB tumors and could be used for targeted therapy.

Breakthrough concepts in immune-oncology: Cancer vaccines at the bedside

Clinical approval of the immune checkpoint blockade (ICB) agents for multiple cancer types has reinvigorated the long-standing work on cancer vaccines. In the pre-ICB era, clinical efforts focused on the Ag, the adjuvants, the formulation, and the mode of delivery. These translational efforts on therapeutic vaccines range from cell-based (e.g., dendritic cells vaccine Sipuleucel-T) to DNA/RNA-based platforms with various formulations (liposome), vectors (Listeria monocytogenes), or modes of delivery (intratumoral, gene gun, etc.). Despite promising preclinical results, cancer vaccine trials without ICB have historically shown little clinical activity. With the anticipation and expansion of combinatorial immunotherapeutic trials with ICB, the cancer vaccine field has entered the personalized medicine arena with recent advances in immunogenic neoantigen-based vaccines. In this article, we review the literature to organize the different cancer vaccines in the clinical space, and we will discuss their advantages, limits, and recent progress to overcome their challenges. Furthermore, we will also discuss recent preclinical advances and clinical strategies to combine vaccines with checkpoint blockade to improve therapeutic outcome and present a translational perspective on future directions.

Computerised scoring protocol for identification and quantification of different immune cell populations in breast tumour regions by the use of QuPath software

AIMS

As important prognostic and predictive information can be obtained from the composition, functionality and spatial arrangement of different immune cell subtypes, this study aims at characterizing the immune infiltrate in breast tumours.

METHODS AND RESULTS

Tumour-infiltrating lymphocytes (TILs) in 62 patients with luminal B-like breast cancer were characterised by immunohistochemical staining with standard markers, and were subsequently classified and quantified by the use of QuPath software. In different delineated tumour regions, the proportion and density of CD3⁺ , CD4⁺ , CD5⁺ , CD8⁺ , CD20⁺ and FOXP3⁺ cells were assessed. The results of the software analysis were compared with those of manual counting for CD8 and CD20 staining. The QuPath scoring protocol slightly overestimated positive, negative and total lymphocyte counts and density, while minimally underestimating the proportion of positively stained lymphocytes. However, for density and proportion, no real differences from manual counting were observed. For all markers, the density of positively stained immune cells was higher in the invasive front than in the tumour centre, pointing to an accumulation of immune cells near the tumour boundaries. When we looked at the proportion of immunohistochemically positive immune cells, we observed enrichment of CD5 (P = 0.025) and CD20 (P < 0.001) at the periphery, and FOXP3 enrichment in the centre (P < 0.001).

CONCLUSION

The QuPath scoring protocol can adequately identify positively stained immune cells in breast tumours, and allows the evaluation of differences in immune cell proportion and density within different tumour regions. The entire tumour section can be quantitatively assessed quite rapidly, which is a major advantage over manual counting.

Induction of Immune Response Against Metastatic Tumors via Vaccination of Mannan-BAM, TLR Ligands and Anti-CD40 Antibody (MBTA)

Emerging evidence is demonstrating the extent of T-cell infiltration within the tumor microenvironment has favorable prognostic and therapeutic implications. Hence, immunotherapeutic strategies that augment the T-cell signature of tumors hold promising therapeutic potential. Recently, immunotherapy based on intratumoral injection of mannan-BAM, toll-like receptor ligands and anti-CD40 antibody (MBTA) demonstrated promising potential to modulate the immune phenotype of injected tumors. The strategy promotes the phagocytosis of tumor cells to facilitate the recognition of tumor antigens and induce a tumor-specific adaptive immune response. Using a syngeneic colon carcinoma model, we demonstrate MBTA's potential to augment CD8⁺ T-cell tumor infiltrate when administered intratumorally or subcutaneously as part of a whole tumor cell vaccine. Both immunotherapeutic strategies proved effective at controlling tumor growth, prolonged survival and induced immunological memory against the parental cell line. Collectively, our investigation demonstrates MBTA's potential to trigger a potent anti-tumor immune response.

High-capacity poly(2-oxazoline) formulation of TLR 7/8 agonist extends survival in a chemo-insensitive, metastatic model of lung adenocarcinoma

About 40% of patients with non-small cell lung cancer (NSCLC) have stage IV cancer at the time of diagnosis. The only viable treatment options for metastatic disease are systemic chemotherapy and immunotherapy. Nonetheless, chemoresistance remains a major cause of chemotherapy failure. New immunotherapeutic modalities such as anti-PD-1 immune checkpoint blockade have shown promise; however, response to such strategies is highly variable across patients. Here, we show that our unique poly(2-oxazoline)-based nanomicellar formulation (PM) of Resiquimod, an imidazoquinoline Toll-like receptor (TLR) 7/8 agonist, had a superior tumor inhibitory effect in a metastatic model of lung adenocarcinoma, relative to anti-PD-1 therapy or platinum-based chemotherapy. Investigation of the in vivo immune status following Resiquimod PM treatment showed that Resiquimod-based stimulation of antigen-presenting cells in the tumor microenvironment resulted in the mobilization of an antitumor CD8+ immune response. Our study demonstrates the promise of poly(2-oxazoline)-formulated Resiquimod for treating metastatic NSCLC.

Enhancing the Efficacy of CAR T Cells in the Tumor Microenvironment of Pancreatic Cancer

Pancreatic cancer has the worst prognosis and lowest survival rate among all types of cancers and thus, there exists a strong need for novel therapeutic strategies. Chimeric antigen receptor (CAR)-modified T cells present a new potential option after successful FDA-approval in hematologic malignancies, however, current CAR T cell clinical trials in pancreatic cancer failed to improve survival and were unable to demonstrate any significant response. The physical and environmental barriers created by the distinct tumor microenvironment (TME) as a result of the desmoplastic reaction in pancreatic cancer present major hurdles for CAR T cells as a viable therapeutic option in this tumor entity. Cancer cells and cancer-associated fibroblasts express extracellular matrix molecules, enzymes, and growth factors, which can attenuate CAR T cell infiltration and efficacy. Recent efforts demonstrate a niche shift where targeting the TME along CAR T cell therapy is believed or hoped to provide a substantial clinical added value to improve overall survival. This review summarizes therapeutic approaches targeting the TME and their effect on CAR T cells as well as their outcome in preclinical and clinical trials in pancreatic cancer.

Adoptive cell transfer (ACT) of autologous tumor-infiltrating lymphocytes (TILs) to treat malignant melanoma: the dawn of a chimeric antigen receptor T (CAR-T) cell therapy from autologous donor

BACKGROUND

Tumor-infiltrating lymphocytes (TILs) are B, T-helper, and T-cytotoxic lymphocytes migrated from the blood or lymph stream toward a tumor with the aim to infiltrate and destroy it. They can be histologically graded as brisk, nonbrisk, or absent. Malignant melanoma has been the first malignancy found to be correlated with TILs status, being brisk TILs associated with better clinical outcomes. By the terminology of "adoptive cell transfer" (ACT), the medical oncology refers to the transfer of cells in a tumor-bearing patient from the same recipient or a healthy donor.

METHODS

A PubMed literature search on the topic has been performed. Additional documents known to the authors and identified from the reference list of cited publications have been included.

RESULTS

In the past, autologous TILs ACT was successfully tested for the treatment of malignant melanoma and, today, it is a standardized procedure in several centers around the world. It represents the first research step toward the bioengineered chimeric antigen receptor T (CAR-T) cell therapy from autologous donor.

CONCLUSIONS

Both autologous TILs ACT and CAR-T cell therapy from autologous donor exploit the anticancer power of targeted self-lymphocytes, but CAR-T cell technology also virtually allows treatment of those melanomas devoid of TILs or with so few cytotoxic TILs that are difficult to identify.

Growth/Differentiation Factor-15 (GDF-15): From Biomarker to Novel Targetable Immune Checkpoint

Growth/differentiation factor-15 (GDF-15), also named macrophage inhibitory cytokine-1, is a divergent member of the transforming growth factor β superfamily. While physiological expression is barely detectable in most somatic tissues in humans, GDF-15 is abundant in placenta. Elsewhere, GDF-15 is often induced under stress conditions, seemingly to maintain cell and tissue homeostasis; however, a moderate increase in GDF-15 blood levels is observed with age. Highly elevated GDF-15 levels are mostly linked to pathological conditions including inflammation, myocardial ischemia, and notably cancer. GDF-15 has thus been widely explored as a biomarker for disease prognosis. Mechanistically, induction of anorexia via the brainstem-restricted GDF-15 receptor GFRAL (glial cell-derived neurotrophic factor [GDNF] family receptor α-like) is well-documented. GDF-15 and GFRAL have thus become attractive targets for metabolic intervention. Still, several GDF-15 mediated effects (including its physiological role in pregnancy) are difficult to explain via the described pathway. Hence, there is a clear need to better understand non-metabolic effects of GDF-15. With particular emphasis on its immunomodulatory potential this review discusses the roles of GDF-15 in pregnancy and in pathological conditions including myocardial infarction, autoimmune disease, and specifically cancer. Importantly, the strong predictive value of GDF-15 as biomarker may plausibly be linked to its immune-regulatory function. The described associations and mechanistic data support the hypothesis that GDF-15 acts as immune checkpoint and is thus an emerging target for cancer immunotherapy.

Personalized neoantigen vaccination with synthetic long peptides: recent advances and future perspectives

Therapeutic cancer vaccines are one of the most promising strategies of immunotherapy. Traditional vaccines consisting of tumor-associated antigens have met with limited success. Recently, neoantigens derived from nonsynonymous mutations in tumor cells have emerged as alternatives that can improve tumor-specificity and reduce on-target off-tumor toxicity. Synthetic peptides are a common platform for neoantigen vaccines. It has been suggested that extending short peptides into long peptides can overcome immune tolerance and induce both CD4⁺ and CD8⁺ T cell responses. This review will introduce the history of long peptide-based neoantigen vaccines, discuss their advantages, summarize current preclinical and clinical developments, and propose future perspectives.