Mutational and Antigenic Landscape in Tumor Progression and Cancer Immunotherapy

Emerging role of immunogenic cell death in cancer immunotherapy: Advancing next-generation CAR-T cell immunotherapy by combination

Immunogenic cell death (ICD) is a stress-driven form of regulated cell death (RCD) in which dying tumor cells' specific signaling pathways are activated to release damage-associated molecular patterns (DAMPs), leading to the robust anti-tumor immune response as well as a reversal of the tumor immune microenvironment from "cold" to "hot". Chimeric antigen receptor (CAR)-T cell therapy, as a landmark in anti-tumor immunotherapy, plays a formidable role in hematologic malignancies but falls short in solid tumors. The Gordian knot of CAR-T cells for solid tumors includes but is not limited to, tumor antigen heterogeneity or absence, physical and immune barriers of tumors. The combination of ICD induction therapy and CAR-T cell immunotherapy is expected to promote the intensive use of CAR-T cell in solid tumors. In this review, we summarize the characteristics of ICD, stress-responsive mechanism, and the synergistic effect of various ICD-based therapies with CAR-T cells to effectively improve anti-tumor capacity.

Recent Advances in Immune-Based Therapies for Acute Myeloid Leukemia

Despite advancements, acute myeloid leukemia (AML) remains unconquered by current therapies. Evidence of immune evasion during AML progression, such as HLA loss and T-cell exhaustion, suggests that antileukemic immune responses contribute to disease control and could be harnessed by immunotherapy. In this review, we discuss a spectrum of AML immunotherapy targets, encompassing cancer cell-intrinsic and surface antigens as well as targeting in the leukemic milieu, and how they can be tailored for personalized approaches. These targets are overviewed across major immunotherapy modalities applied to AML: immune checkpoint inhibitors, antibody-drug conjugates, therapeutic vaccines, bispecific/trispecific antibodies, and chimeric antigen receptor (CAR)-T and CAR-NK cells. Significance: Immune therapies in AML treatment show evolving promise. Ongoing research aims to customize approaches for varied patient profiles and clinical scenarios. This review covers immune surveillance mechanisms, therapy options like checkpoint inhibitors, antibodies, CAR-T/NK cells, and vaccines, as well as resistance mechanisms and microenvironment considerations.

Clinical application of immunogenic cell death inducers in cancer immunotherapy: turning cold tumors hot

Immunotherapy has emerged as a promising cancer treatment option in recent years. In immune "hot" tumors, characterized by abundant immune cell infiltration, immunotherapy can improve patients' prognosis by activating the function of immune cells. By contrast, immune "cold" tumors are often less sensitive to immunotherapy owing to low immunogenicity of tumor cells, an immune inhibitory tumor microenvironment, and a series of immune-escape mechanisms. Immunogenic cell death (ICD) is a promising cellular process to facilitate the transformation of immune "cold" tumors to immune "hot" tumors by eliciting innate and adaptive immune responses through the release of (or exposure to) damage-related molecular patterns. Accumulating evidence suggests that various traditional therapies can induce ICD, including chemotherapy, targeted therapy, radiotherapy, and photodynamic therapy. In this review, we summarize the biological mechanisms and hallmarks of ICD and introduce some newly discovered and technologically innovative inducers that activate the immune system at the molecular level. Furthermore, we also discuss the clinical applications of combing ICD inducers with cancer immunotherapy. This review will provide valuable insights into the future development of ICD-related combination therapeutics and potential management for "cold" tumors.

The senescence journey in cancer immunoediting

Cancer progression is continuously controlled by the immune system which can identify and destroy nascent tumor cells or inhibit metastatic spreading. However, the immune system and its deregulated activity in the tumor microenvironment can also promote tumor progression favoring the outgrowth of cancers capable of escaping immune control, in a process termed cancer immunoediting. This process, which has been classified into three phases, i.e. "elimination", "equilibrium" and "escape", is influenced by several cancer- and microenvironment-dependent factors. Senescence is a cellular program primed by cells in response to different pathophysiological stimuli, which is based on long-lasting cell cycle arrest and the secretion of numerous bioactive and inflammatory molecules. Because of this, cellular senescence is a potent immunomodulatory factor promptly recruiting immune cells and actively promoting tissue remodeling. In the context of cancer, these functions can lead to both cancer immunosurveillance and immunosuppression. In this review, the authors will discuss the role of senescence in cancer immunoediting, highlighting its context- and timing-dependent effects on the different three phases, describing how senescent cells promote immune cell recruitment for cancer cell elimination or sustain tumor microenvironment inflammation for immune escape. A potential contribution of senescent cells in cancer dormancy, as a mechanism of therapy resistance and cancer relapse, will be discussed with the final objective to unravel the immunotherapeutic implications of senescence modulation in cancer.

ZNF689 deficiency promotes intratumor heterogeneity and immunotherapy resistance in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is an aggressive disease characterized by remarkable intratumor heterogeneity (ITH), which poses therapeutic challenges. However, the clinical relevance and key determinant of ITH in TNBC are poorly understood. Here, we comprehensively characterized ITH levels using multi-omics data across our center's cohort (n = 260), The Cancer Genome Atlas cohort (n = 134), and four immunotherapy-treated cohorts (n = 109). Our results revealed that high ITH was associated with poor patient survival and immunotherapy resistance. Importantly, we identified zinc finger protein 689 (ZNF689) deficiency as a crucial determinant of ITH formation. Mechanistically, the ZNF689-TRIM28 complex was found to directly bind to the promoter of long interspersed element-1 (LINE-1), inducing H3K9me3-mediated transcriptional silencing. ZNF689 deficiency reactivated LINE-1 retrotransposition to exacerbate genomic instability, which fostered ITH. Single-cell RNA sequencing, spatially resolved transcriptomics and flow cytometry analysis confirmed that ZNF689 deficiency-induced ITH inhibited antigen presentation and T-cell activation, conferring immunotherapy resistance. Pharmacological inhibition of LINE-1 significantly reduced ITH, enhanced antitumor immunity, and eventually sensitized ZNF689-deficient tumors to immunotherapy in vivo. Consistently, ZNF689 expression positively correlated with favorable prognosis and immunotherapy response in clinical samples. Altogether, our study uncovers a previously unrecognized mechanism underlying ZNF689 deficiency-induced ITH and suggests LINE-1 inhibition combined with immunotherapy as a novel treatment strategy for TNBC.

In Vitro Evaluation of Cancer Cell Immunogenicity and Antigen-Specific T-Cell Cytotoxicity by Flow Cytometry

A cardinal principle of oncoimmunology is that cancer cells can be eliminated by tumor-infiltrating cytotoxic CD8 T lymphocytes. This has been widely demonstrated during the last 20 years and also recently harnessed for therapy. However, emerging evidence indicates that even neoplasms showing striking initial responses to conventional and targeted (immuno)therapies often acquire resistance, resulting in tumor relapse, increased aggressiveness, and metastatization. Indeed, tumors are complex ecosystems whose malignant and nonmalignant cells, constituting the tumor microenvironment, constantly interact and evolve in space and time. Together with patient's own genetic factors, such environmental interplays may curtail antitumor immune responses leading to cancer immune evasion and natural/acquired (immuno)therapy resistance. In this context, cancer stem cells (CSCs) are thought to be the roots of therapy failure. Flow cytometry is a powerful technology that finds extensive applications in cancer biology. It offers several unique advantages as it allows the rapid, quantitative, and multiparametric analysis of cell populations or functions at the single-cell level. In this chapter, we discuss a two-color flow cytometric protocol to evaluate cancer cell immunogenicity by analyzing the proliferative and tumor-killing potential of ovalbumin (OVA)-specific CD8 OT-1 T cells exposed to OVA-expressing MCA205 sarcoma cells and their CSC counterparts.

Crosstalk between endoplasmic reticulum stress and multidrug-resistant cancers: hope or frustration

Endoplasmic reticulum stress (ERS) is a kind of cell response for coping with hypoxia and other stresses. Pieces of evidence show that continuous stress can promote the occurrence, development, and drug resistance of tumors through the unfolded protein response. Therefore, the abnormal ac-tivation of ERS and its downstream signaling pathways not only can regulate tumor growth and metastasis but also profoundly affect the efficacy of antitumor therapy. Therefore, revealing the molecular mechanism of ERS may be expected to solve the problem of tumor multidrug resistance (MDR) and become a novel strategy for the treatment of refractory and recurrent tumors. This re-view summarized the mechanism of ERS and tumor MDR, reviewed the relationship between ERS and tumor MDR, introduced the research status of tumor tissue and ERS, and previewed the prospect of targeting ERS to improve the therapeutic effect of tumor MDR. This article aims to provide researchers and clinicians with new ideas and inspiration for basic antitumor treatment.

Dendritic Cell Vaccines: A Shift from Conventional Approach to New Generations

In the emerging era of cancer immunotherapy, immune checkpoint blockades (ICBs) and adoptive cell transfer therapies (ACTs) have gained significant attention. However, their therapeutic efficacies are limited due to the presence of cold type tumors, immunosuppressive tumor microenvironment, and immune-related side effects. On the other hand, dendritic cell (DC)-based vaccines have been suggested as a new cancer immunotherapy regimen that can address the limitations encountered by ICBs and ACTs. Despite the success of the first generation of DC-based vaccines, represented by the first FDA-approved DC-based therapeutic cancer vaccine Provenge, several challenges remain unsolved. Therefore, new DC vaccine strategies have been actively investigated. This review addresses the limitations of the currently most adopted classical DC vaccine and evaluates new generations of DC vaccines in detail, including biomaterial-based, immunogenic cell death-inducing, mRNA-pulsed, DC small extracellular vesicle (sEV)-based, and tumor sEV-based DC vaccines. These innovative DC vaccines are envisioned to provide a significant breakthrough in cancer immunotherapy landscape and are expected to be supported by further preclinical and clinical studies.

The Therapeutic Potential of a Strategy to Prevent Acute Myeloid Leukemia Stem Cell Reprogramming in Older Patients

Acute myeloid leukemia (AML) is the most common and incurable leukemia subtype. Despite extensive research into the disease's intricate molecular mechanisms, effective treatments or expanded diagnostic or prognostic markers for AML have not yet been identified. The morphological, immunophenotypic, cytogenetic, biomolecular, and clinical characteristics of AML patients are extensive and complex. Leukemia stem cells (LSCs) consist of hematopoietic stem cells (HSCs) and cancer cells transformed by a complex, finely-tuned interaction that causes the complexity of AML. Microenvironmental regulation of LSCs dormancy and the diagnostic and therapeutic implications for identifying and targeting LSCs due to their significance in the pathogenesis of AML are discussed in this review. It is essential to perceive the relationship between the niche for LSCs and HSCs, which together cause the progression of AML. Notably, methylation is a well-known epigenetic change that is significant in AML, and our data also reveal that microRNAs are a unique factor for LSCs. Multiple-targeted approaches to reduce the risk of epigenetic factors, such as the administration of natural compounds for the elimination of local LSCs, may prevent potentially fatal relapses. Furthermore, the survival analysis of overlapping genes revealed that specific targets had significant effects on the survival and prognosis of patients. We predict that the multiple-targeted effects of herbal products on epigenetic modification are governed by different mechanisms in AML and could prevent potentially fatal relapses. Thus, these strategies can facilitate the incorporation of herbal medicine and natural compounds into the advanced drug discovery and development processes achievable with Network Pharmacology research.

Genomic and molecular landscape of homologous recombination deficiency across multiple cancer types

Homologous recombination deficiency (HRD) causes faulty double-strand break repair and is a prevalent cause of tumorigenesis. However, the incidence of HRD and its clinical significance in pan-cancer patients remain unknown. Using computational analysis of Single-nucleotide polymorphism array data from 10,619 cancer patients, we demonstrate that HRD frequently occurs across multiple cancer types. Analysis of the pan-cancer cohort revealed that HRD is not only a biomarker for ovarian cancer and triple-negative breast cancer, but also has clinical prognostic value in numerous cancer types, including adrenocortical cancer and thymoma. We discovered that homologous recombination-related genes have a high mutation or deletion frequency. Pathway analysis shows HRD is positively correlated with the DNA damage response and the immune-related signaling pathways. Single cell RNA sequencing of tumor-infiltrating lymphocytes reveals a significantly higher proportion of exhausted T cells in HRD patients, indicating pre-existing immunity. Finally, HRD could be utilized to predict pan-cancer patients' responses to Programmed cell death protein 1 immunotherapy. In summary, our work establishes a comprehensive map of HRD in pan-cancer. The findings have significant implications for expanding the scope of Poly ADP-ribose polymerase inhibitor therapy and, possibly, immunotherapy.

Immunogenic cell death in cancer: concept and therapeutic implications

Mammalian cells responding to specific perturbations of homeostasis can undergo a regulated variant of cell death that elicits adaptive immune responses. As immunogenic cell death (ICD) can only occur in a precise cellular and organismal context, it should be conceptually differentiated from instances of immunostimulation or inflammatory responses that do not mechanistically depend on cellular demise. Here, we critically discuss key conceptual and mechanistic aspects of ICD and its implications for cancer (immuno)therapy.

Evaluation of immunotherapy efficacy in gynecologic cancer

Various immunotherapies have demonstrated remarkable success over the past few decades, and have been approved for the treatment of different cancer types. However, patient responses to immunotherapy are variable, and approximately 50% of cases are refractory to these agents. Tumor biomarker-based stratification of cases may therefore help identify subpopulations that are sensitive/resistant to immunotherapy; it may also improve prediction of response in various cancers including gynecologic cancer. These biomarkers include the tumor mutational burden, microsatellite instability, mismatch repair deficiency, T cell-inflamed gene expression profile, programmed cell death protein 1 ligand 1, tumor-infiltrating lymphocytes, and numerous other genomic alterations. Future directions in the treatment of gynecologic cancer include the utilization of these biomarkers to select ideal candidates. This review focused on recent advances in the predictive ability of molecular biomarkers in patients with gynecologic cancer who undergo immunotherapy. The most recent developments in combined immunotherapy and targeted therapy strategies and novel immune interventions against gynecologic cancers have also been discussed.

Metabolic rearrangements and intratumoral heterogeneity for immune response in hepatocellular carcinoma

Liver cancer is one of the most common malignant tumors globally. Not only is it difficult to diagnose, but treatments are scarce and the prognosis is generally poor. Hepatocellular carcinoma (HCC) is the most common type of liver cancer. Aggressive cancer cells, such as those found in HCC, undergo extensive metabolic rewiring as tumorigenesis, the unique feature, ultimately causes adaptation to the neoplastic microenvironment. Intratumoral heterogeneity (ITH) is defined as the presence of distinct genetic features and different phenotypes in the same tumoral region. ITH, a property unique to malignant cancers, results in differences in many different features of tumors, including, but not limited to, tumor growth and resistance to chemotherapy, which in turn is partly responsible for metabolic reprogramming. Moreover, the different metabolic phenotypes might also activate the immune response to varying degrees and help tumor cells escape detection by the immune system. In this review, we summarize the reprogramming of glucose metabolism and tumoral heterogeneity and their associations that occur in HCC, to obtain a better understanding of the mechanisms of HCC oncogenesis.

T Cell-Mediated Tumor Killing-Related Classification of the Immune Microenvironment and Prognosis Prediction of Lung Adenocarcinoma

BACKGROUND

Although immune checkpoint inhibitors (ICI) are a promising therapeutic strategy for lung adenocarcinoma (LUAD), individual subgroups that might benefit from them are yet to be identified. As T cell-mediated tumor killing (TTK) is an underlying mechanism of ICI, we identified subtypes based on genes associated with TTK sensitivity and assessed their predictive significance for LUAD immunotherapies.

METHODS

Using high-throughput screening techniques, genes regulating the sensitivity of T cell-mediated tumor killing (GSTTK) with differential expression and associations with prognosis were discovered in LUAD. Furthermore, patients with LUAD were divided into subgroups using unsupervised clustering based on GSTTK. Significant differences were observed in the tumor immune microenvironment (TIME), genetic mutation and immunotherapy response across subgroups. Finally, the prognostic significance of a scoring algorithm based on GSTTK was assessed.

RESULTS

A total of 6 out of 641 GSTTK exhibited differential expression in LUAD and were associated with prognosis. Patients were grouped into two categories based on the expression of the six GSTTK, which represented different TTK immune microenvironments in LUAD. Immune cell infiltration, survival difference, somatic mutation, functional enrichment and immunotherapy responses also varied between the two categories. Additionally, a scoring algorithm accurately distinguished overall survival rates across populations.

CONCLUSIONS

TTK had a crucial influence on the development of the varying TIME. Evaluation of the varied TTK modes of different tumors enhanced our understanding of TIME characteristics, wherein the changes in T cell activity in LUAD are reflected. Thus, this study guides the development of more effective therapeutic methods.

Discovery and characterization of tumor antigens in hepatocellular carcinoma for mRNA vaccine development

BACKGROUND

mRNA vaccines are emerging as new targets for cancer immunotherapy. However, the potential tumor antigens for mRNA vaccine design in hepatocellular carcinoma (HCC) remain to be elucidated.

METHODS

Genetic and RNA-Seq data were obtained from TCGA and ICGC. Tumor-specific antigens (TSAs) were identified by differential expression, mutation status, HLA binding, antigen-presenting cell (APC) correlation, immune checkpoint (ICP) relevance and prognosis. Consensus clustering was used for patient classification. The molecular and immune status of TSAs and clustered patients, including prognostic ability, tumor microenvironment, tumor-related signature and tumor immune dysfunction and exclusion (TIDE), were further characterized.

RESULTS

Five dysregulated and mutated TSAs were identified in HCC (TSA5): FXYD6, JAM2, GALNT16, C7, and CCDC146. Seven immune gene modules and five immune subtypes (IS1-IS5) of HCC were identified. The immune subtypes and TSA5-related modules showed distinct molecular, cellular and clinical characteristics. According to our study, IS1 patients may be suitable for vaccination.

Flavonoids regulate tumor-associated macrophages - From structure-activity relationship to clinical potential (Review)

In recent years, the strategy for tumor therapy has changed from focusing on the direct killing effect of different types of therapeutic agents on cancer cells to the new mainstream of multi-mode and -pathway combined interventions in the microenvironment of the developing tumor. Flavonoids, with unique tricyclic structures, have diverse and extensive immunomodulatory and anti-cancer activities in the tumor microenvironment (TME). Tumor-associated macrophages (TAMs) are the most abundant immunosuppressive cells in the TME. The regulation of macrophages to fight cancer is a promising immunotherapeutic strategy. This study covers the most comprehensive cognition of flavonoids in regulating TAMs so far. Far more than a simple list of studies, we try to dig out evidence of crosstalk at the molecular level between flavonoids and TAMs from literature, in order to discuss the most relevant chemical structure and its possible relationship with the multimodal pharmacological activity, as well as systematically build a structure-activity relationship between flavonoids and TAMs. Additionally, we point out the advantages of the macro-control of flavonoids in the TME and discuss the potential clinical implications as well as areas for future research of flavonoids in regulating TAMs. These results will provide hopeful directions for the research of antitumor drugs, while providing new ideas for the pharmaceutical industry to develop more effective forms of flavonoids.

Differential Infiltration of Immune Cells Driven by Tumor Heterogeneity Reveals Two Immune Subtypes in Lung Adenocarcinoma

Intra-tumoral heterogeneity (ITH) is a critical factor leading to aggressive progression and response to immunotherapy in lung adenocarcinoma (LUAD). However, the relationship between ITH and immune cells in the tumor microenvironment (TME) has not been systematically elucidated. In the present study, we evaluated the ITH status of LUAD samples based on the mutational data obtained from The Cancer Genome Atlas database. First, we identified five key immune pathways with a significantly continuous downtrend among normal, low-heterogeneous, and high-heterogeneous samples and further excavated nine key immune cells related to the key immune pathways and tumor heterogeneity. Then, two immune subtypes were defined by a consensus clustering algorithm based on the infiltration of these immune cells. Differences between these two immune subtypes were remarkable, including alterations of tumor mutation burden and DNA copy number variation at the genomic level, various metabolic pathways, and the different clinical outcome, which was also validated in two independent Gene Expression Omnibus datasets. The results revealed that ITH was significantly associated with prognosis and infiltrating immune cells in the TME. Our study provides novel insights in understanding the relationship between ITH and immune cells and contributes to the immunotherapy of LUAD patients.

A promising Prognostic risk model for advanced renal cell carcinoma (RCC) with immune-related genes

Background

Renal cell carcinoma (RCC) is a third most common tumor of the urinary system. Nowadays, Immunotherapy is a hot topic in the treatment of solid tumors, especially for those tumors with pre-activated immune state.

Methods

In this study, we downloaded genomic and clinical data of RCC samples from The Cancer Genome Atlas (TCGA) database. Four immune-related genetic signatures were used to predict the prognosis of RCC by Cox regression analysis. Then we established a prognostic risk model consisting of the genes most related to prognosis from four signatures to value prognosis of the RCC samples via Kaplan–Meier (KM) survival analysis. An independent data from International Cancer Genome Consortium (ICGC) database were used to test the predictive stability of the model. Furthermore, we performed landscape analysis to assess the difference of gene mutant in the RCC samples from TCGA. Finally, we explored the correlation between the selected genes and the level of tumor immune infiltration via Tumor Immune Estimation Resource (TIMER) platform.

Results

We used four genetic signatures to construct prognostic risk models respectively and found that each of the models could divide the RCC samples into high- and low-risk groups with significantly different prognosis, especially in advanced RCC. A comprehensive prognostic risk model was constructed by 8 candidate genes from four signatures (HLA-B, HLA-A, HLA-DRA, IDO1, TAGAP, CIITA, PRF1 and CD8B) dividing the advanced RCC samples from TCGA database into high-risk and low-risk groups with a significant difference in cancer-specific survival (CSS). The stability of the model was verified by independent data from ICGC database. And the classification efficiency of the model was stable for the samples from different subgroups. Landscape analysis showed that mutation ratios of some genes were different between two risk groups. In addition, the expression levels of the selected genes were significantly correlated with the infiltration degree of immune cells in the advanced RCC.

Conclusions

Sum up, eight immune-related genes were screened in our study to construct prognostic risk model with great predictive value for the prognosis of advanced RCC, and the genes were associated with infiltrating immune cells in tumors which have potential to conduct personalized treatment for advanced RCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09755-2.

Rational design of synthetically tractable HDAC6/HSP90 dual inhibitors to destroy immune-suppressive tumor microenvironment

INTRODUCTION

The tumor microenvironment is mainly flooded with immunosuppressive cells and inhibitory cytokines, resulting in the inability of effective immune cells to infiltrate and recognize tumors and even the loss of anti-cancer ability.

OBJECTIVES

We propose a novel HDAC6/HSP90 dual inhibitory strategy as well as a chemoimmunotherapeutic agent that does not only kill tumor cells but also destroys the tumor microenvironment and enhances anti-cancer immunity.

METHODS

A hybrid scaffold construction approach was leveraged to furnish a series of rationally designed resorcinol-based hydroxamates as dual selective HDAC6/HSP90 inhibitors. The drug design campaign commenced with a fragment recruitment process to pinpoint validated structural units to inhibit HDAC6 and HSP90, followed by their installation in flexible HDAC inhibitory templates via an efficient and facile multistep synthetic route. Subsequent evaluations identified a strikingly potent selective HDAC6/HSP90 dual inhibitor (compound 17) via molecular and biological analysis in vitro and in vivo.

RESULTS

Compound 17 exhibited not only direct cytotoxicity to cancer cells but also downregulated immune checkpoints (PD-L1 and IDO) expression in tumors via the inhibition of STAT1 pathway and degradation of oncogene proteins (Src, AKT, Rb, and FAK), leading to in vivo tumor growth inhibition. These multiple effects enabled the effector T cells to largely infiltrate into the tumor region and release granzyme B to kill cancer cells. In addition, compound 17 also decreased TGF-β secretion from normal cells, resulting in the systemic reduction of immunosuppressive regulatory T cells. Delightfully, a cocktail treatment of compound 17 and anti-PD-1 antibodies demonstrated synergistic efficacy to eliminate solid tumors with 83.9% of tumor growth inhibition.

CONCLUSION

In summary, the impressive activity profile of compound 17, as an effective anticancer agent and a potential immunosensitizer, forecasts the application of HDAC6/HSP90 dual inhibitory strategy to overcome the immunosuppressive tumor microenvironment.

Recent insights into the effects of metabolism on breast cancer cell dormancy

Breast cancer (BC) remains the most common cancer, as well as the leading cause of cancer mortality in women worldwide [1]. Approximately 30% of patients with early-stage BC experience metastasis or a recurrent form of the disease [2]. The phenomenon of BC dormancy, where metastasised cancer cells remain in a quiescent phase at their disseminated location and for unknown reasons can become actively proliferative again, further adds to BC’s clinical burden with treatment at this secondary stage typically proving futile. An emerging avenue of research focuses on the metabolic properties of dormant BC cells (BCCs) and potential metabolic changes causing BCCs to enter/exit their quiescent state. Here we explore several studies that have uncovered changes in carbon metabolism underlying a dormant state, with conflicting studies uncovering shifts towards both glycolysis and/or oxidative phosphorylation. This review highlights that the metabolic states/shifts of dormant BCCs seem to be dependent on different BC subtypes and receptor status; however, more work needs to be done to fully map these differences. Building on the research that this review outlines could provide new personalised therapeutic possibilities for BC patients.

Investigating the Clinico-Molecular and Immunological Evolution of Lung Adenocarcinoma Using Pseudotime Analysis

Introduction

As the molecular features of lung adenocarcinoma (LUAD) have been evaluated as a cross-sectional study, the course of tumor characteristics has not been modeled. The temporal evolution of the tumor immune microenvironment (TIME), as well as the clinico-molecular features of LUAD, could provide a precise strategy for immunotherapy and surrogate biomarkers for the course of LUAD.

Methods

A pseudotime trajectory was constructed in patients with LUAD from the Cancer Genome Atlas and non-small cell lung cancer radiogenomics datasets. Correlation analyses were performed between clinical features and pseudotime. Genes associated with pseudotime were selected, and gene ontology analysis was performed. F-18 fluorodeoxyglucose positron emission tomography images of subjects were collected, and imaging parameters, including standardized uptake value (SUV), were obtained. Correlation analyses were performed between imaging parameters and pseudotime. Correlation analyses were performed between the enrichment scores of various immune cell types and pseudotime. In addition, correlation analyses were performed between the expression of PD-L1, tumor mutation burden, and pseudotime.

Results

Pseudotime trajectories of LUAD corresponded to clinical stages. Molecular profiles related to cell division and natural killer cell activity were changed along the pseudotime. The maximal SUV of LUAD tumors showed a positive correlation with pseudotime. Type 1 helper T (Th1) cells showed a positive correlation, whereas M2 macrophages showed a negative correlation with pseudotime. PD-L1 expression showed a negative correlation, whereas tumor mutation burden showed a positive correlation with pseudotime.

Conclusion

The estimated pseudotime associated with the stage suggested that it could reflect the clinico-molecular evolution of LUAD. Specific immune cell types in the TIME as well as cell division and glucose metabolism were dynamically changed according to the progression of the pseudotime. As a molecular progression of LUAD, different cellular targets should be considered for immunotherapy.

Spatial distribution and functional analysis define the action pathway of Tim-3/Tim-3 ligands in tumor development

The spatial organization of immune cells within the tumor microenvironment (TME) largely determines the anti-tumor immunity and also highly predicts tumor progression and therapeutic response. Tim-3 is a well-accepted immune checkpoint and plays multifaceted immunoregulatory roles via interaction with distinct Tim-3 ligands (Tim-3L), showing great potential as an immunotherapy target. However, the cell sociology mediated by Tim-3/Tim-3L and their contribution to tumor development remains elusive. Here, we analyzed the spatial distribution of Tim-3/Tim-3L in TME using multiplex fluorescence staining and revealed that despite the increased Tim-3 expression in various tumor-infiltrated lymphocytes, Tim-3⁺CD4⁺ cells were more accumulated in parenchymal/tumor region compared with stromal region and exhibited more close association with patient survival. Strikingly, CD4 T cells surrounding Tim-3L⁺ cells expressed higher Tim-3 than other cells in cancerous tissues. In vivo studies confirmed that depletion of CD4 T cells completely abrogated the inhibition of tumor growth and metastasis, as well as the functional improvement of CD8 T and NK, mediated by Tim-3 blockade, which was further validated in peripheral lymphocytes from patients with hepatocellular carcinoma. In conclusion, our findings unravel the importance of CD4 T cells in Tim-3/Tim-3L-mediated immunosuppression and provide new thoughts for Tim-3 targeted cancer immunotherapy.

Cancer Stem Cells in Ovarian Cancer-A Source of Tumor Success and a Challenging Target for Novel Therapies

Ovarian cancer is the most lethal neoplasm of the female genital organs. Despite indisputable progress in the treatment of ovarian cancer, the problems of chemo-resistance and recurrent disease are the main obstacles for successful therapy. One of the main reasons for this is the presence of a specific cell population of cancer stem cells. The aim of this review is to show the most contemporary knowledge concerning the biology of ovarian cancer stem cells (OCSCs) and their impact on chemo-resistance and prognosis in ovarian cancer patients, as well as to present the treatment options targeted exclusively on the OCSCs. The review presents data concerning the role of cancer stem cells in general and then concentrates on OCSCs. The surface and intracellular OCSCs markers and their meaning both for cancer biology and clinical prognosis, signaling pathways specifically activated in OCSCs, the genetic and epigenetic regulation of OCSCs function including the recent studies on the non-coding RNA regulation, cooperation between OCSCs and the tumor microenvironment (ovarian cancer niche) including very specific environment such as ascites fluid, the role of shear stress, autophagy and metabolic changes for the function of OCSCs, and finally mechanisms of OCSCs escape from immune surveillance, are described and discussed extensively. The possibilities of anti-OCSCs therapy both in experimental settings and in clinical trials are presented, including the recent II phase clinical trials and immunotherapy. OCSCs are a unique population of cancer cells showing a great plasticity, self-renewal potential and resistance against anti-cancer treatment. They are responsible for the progression and recurrence of the tumor. Several completed and ongoing clinical trials have tested different anti-OCSCs drugs which, however, have shown unsatisfactory efficacy in most cases. We propose a novel approach to ovarian cancer diagnosis and therapy.

Immunological control of ovarian carcinoma by chemotherapy and targeted anticancer agents

At odds with other solid tumors, epithelial ovarian cancer (EOC) is poorly sensitive to immune checkpoint inhibitors (ICIs), largely reflecting active immunosuppression despite CD8⁺ T cell infiltration at baseline. Accumulating evidence indicates that both conventional chemotherapeutics and targeted anticancer agents commonly used in the clinical management of EOC not only mediate a cytostatic and cytotoxic activity against malignant cells, but also drive therapeutically relevant immunostimulatory or immunosuppressive effects. Here, we discuss such an immunomodulatory activity, with a specific focus on molecular and cellular pathways that can be harnessed to develop superior combinatorial regimens for clinical EOC care.

Influence of T Cell-Mediated Immune Surveillance on Somatic Mutation Occurrences in Melanoma

Background

Neoantigens are presented on the cancer cell surface by peptide-restricted human leukocyte antigen (HLA) proteins and can subsequently activate cognate T cells. It has been hypothesized that the observed somatic mutations in tumors are shaped by immunosurveillance.

Methods

We investigated all somatic mutations identified in The Cancer Genome Atlas (TCGA) Skin Cutaneous Melanoma (SKCM) samples. By applying a computational algorithm, we calculated the binding affinity of the resulting neo-peptides and their corresponding wild-type peptides with the major histocompatibility complex (MHC) Class I complex. We then examined the relationship between binding affinity alterations and mutation frequency.

Results

Our results show that neoantigens derived from recurrent mutations tend to have lower binding affinities with the MHC Class I complex compared to peptides from non-recurrent mutations. Tumor samples harboring recurrent SKCM mutations exhibited lower immune infiltration levels, indicating a relatively colder immune microenvironment.

Conclusions

These results suggested that the occurrences of somatic mutations in melanoma have been shaped by immunosurveillance. Mutations that lead to neoantigens with high MHC class I binding affinity are more likely to be eliminated and thus are less likely to be present in tumors.

Impact of Cancer Stem Cells and Cancer Stem Cell-Driven Drug Resiliency in Lung Tumor: Options in Sight

Causing a high mortality rate worldwide, lung cancer remains an incurable malignancy resistant to conventional therapy. Despite the discovery of specific molecular targets and new treatment strategies, there remains a pressing need to develop more efficient therapy to further improve the management of this disease. Cancer stem cells (CSCs) are considered the root of sustained tumor growth. This consensus corroborates the CSC model asserting that a distinct subpopulation of malignant cells within a tumor drives and maintains tumor progression with high heterogeneity. Besides being highly tumorigenic, CSCs are highly refractory to standard drugs; therefore, cancer treatment should be focused on eliminating these cells. Herein, we present the current knowledge of the existence of CSCs, CSC-associated mechanisms of chemoresistance, the ability of CSCs to evade immune surveillance, and potential CSC inhibitors in lung cancer, to provide a wider insight to drive a more efficient elimination of this pro-oncogenic and treatment-resistant cell fraction.

Therapeutic cancer vaccines revamping: technology advancements and pitfalls

Cancer vaccines (CVs) represent a long-sought therapeutic and prophylactic immunotherapy strategy to obtain antigen (Ag)-specific T-cell responses and potentially achieve long-term clinical benefit. However, historically, most CV clinical trials have resulted in disappointing outcomes, despite promising signs of immunogenicity across most formulations. In the past decade, technological advances regarding vaccine delivery platforms, tools for immunogenomic profiling, and Ag/epitope selection have occurred. Consequently, the ability of CVs to induce tumor-specific and, in some cases, remarkable clinical responses have been observed in early-phase clinical trials. It is notable that the record-breaking speed of vaccine development in response to the coronavirus disease-2019 pandemic mainly relied on manufacturing infrastructures and technological platforms already developed for CVs. In turn, research, clinical data, and infrastructures put in place for the severe acute respiratory syndrome coronavirus 2 pandemic can further speed CV development processes. This review outlines the main technological advancements as well as major issues to tackle in the development of CVs. Possible applications for unmet clinical needs will be described, putting into perspective the future of cancer vaccinology.

Narrative review of emerging roles for AKT-mTOR signaling in cancer radioimmunotherapy

OBJECTIVE

To summarize the roles of AKT-mTOR signaling in the regulation of the DNA damage response and PD-L1 expression in cancer cells, and propose a novel strategy of targeting AKT-mTOR signaling in combination with radioimmunotherapy in the era of cancer immunotherapy.

BACKGROUND

Immunotherapy has greatly improved the clinical outcomes of many cancer patients and has changed the landscape of cancer patient management. However, only a small subgroup of cancer patients (~20-30%) benefit from immune checkpoint blockade-based immunotherapy. The current challenge is to find biomarkers to predict the response of patients to immunotherapy and strategies to sensitize patients to immunotherapy.

METHODS

Search and review the literature which were published in PUBMED from 2000-2021 with the key words mTOR, AKT, drug resistance, DNA damage response, immunotherapy, PD-L1, DNA repair, radioimmunotherapy.

CONCLUSIONS

More than 50% of cancer patients receive radiotherapy during their course of treatment. Radiotherapy has been shown to reduce the growth of locally irradiated tumors as well as metastatic non-irradiated tumors (abscopal effects) by affecting systemic immunity. Consistently, immunotherapy has been demonstrated to enhance radiotherapy with more than one hundred clinical trials of radiation in combination with immunotherapy (radioimmunotherapy) across cancer types. Nevertheless, current available data have shown limited efficacy of trials testing radioimmunotherapy. AKT-mTOR signaling is a major tumor growth-promoting pathway and is upregulated in most cancers. AKT-mTOR signaling is activated by growth factors as well as genotoxic stresses including radiotherapy. Importantly, recent advances have shown that AKT-mTOR is one of the main signaling pathways that regulate DNA damage repair as well as PD-L1 levels in cancers. These recent advances clearly suggest a novel cancer therapy strategy by targeting AKT-mTOR signaling in combination with radioimmunotherapy.

The Immune Privilege of Cancer Stem Cells: A Key to Understanding Tumor Immune Escape and Therapy Failure

Cancer stem cells (CSCs) are broadly considered immature, multipotent, tumorigenic cells within the tumor mass, endowed with the ability to self-renew and escape immune control. All these features contribute to place CSCs at the pinnacle of tumor aggressiveness and (immune) therapy resistance. The immune privileged status of CSCs is induced and preserved by various mechanisms that directly affect them (e.g., the downregulation of the major histocompatibility complex class I) and indirectly are induced in the host immune cells (e.g., activation of immune suppressive cells). Therefore, deeper insights into the immuno-biology of CSCs are essential in our pursuit to find new therapeutic opportunities that eradicate cancer (stem) cells. Here, we review and discuss the ability of CSCs to evade the innate and adaptive immune system, as we offer a view of the immunotherapeutic strategies adopted to potentiate and address specific subsets of (engineered) immune cells against CSCs.

Hyperthermia and Tumor Immunity

Thermal ablation is a cornerstone in the management of cancer patients. Typically, ablation procedures are performed for patients with a solitary or oligometastatic disease with the intention of eradicating all sites of the disease. Ablation has traditionally played a less prominent role for patients with a widely metastatic disease. For such patients, attempting to treat numerous sites of disease compounds potential risks without a clear clinical benefit and, as such, a compelling justification for performing an intervention that is unlikely to alter a patient's clinical trajectory is uncommon. However, the discovery of immune checkpoints and the development of immune checkpoint inhibitors have brought a new perspective to the relevance of local cancer therapies such as ablation for patients with a metastatic disease. It is becoming increasingly apparent that local cancer therapies can have systemic immune effects. Thus, in the new perspective of cancer care centered upon immunologic principles, there is a strong interest in exploring the utility of ablation for patients with a metastatic disease for its immunologic implications. In this review, we summarize the unmet clinical need for adjuvant interventions such as ablation to broaden the impact of systemic immunotherapies. We additionally highlight the extant preclinical and clinical data for the immunogenicity of common thermal ablation modalities.

Intratumoral heterogeneity in cancer progression and response to immunotherapy

Most (if not all) tumors emerge and progress under a strong evolutionary pressure imposed by trophic, metabolic, immunological, and therapeutic factors. The relative impact of these factors on tumor evolution changes over space and time, ultimately favoring the establishment of a neoplastic microenvironment that exhibits considerable genetic, phenotypic, and behavioral heterogeneity in all its components. Here, we discuss the main sources of intratumoral heterogeneity and its impact on the natural history of the disease, including sensitivity to treatment, as we delineate potential strategies to target such a detrimental feature of aggressive malignancies.

Detection of immunogenic cell death and its relevance for cancer therapy

Chemotherapy, radiation therapy, as well as targeted anticancer agents can induce clinically relevant tumor-targeting immune responses, which critically rely on the antigenicity of malignant cells and their capacity to generate adjuvant signals. In particular, immunogenic cell death (ICD) is accompanied by the exposure and release of numerous damage-associated molecular patterns (DAMPs), which altogether confer a robust adjuvanticity to dying cancer cells, as they favor the recruitment and activation of antigen-presenting cells. ICD-associated DAMPs include surface-exposed calreticulin (CALR) as well as secreted ATP, annexin A1 (ANXA1), type I interferon, and high-mobility group box 1 (HMGB1). Additional hallmarks of ICD encompass the phosphorylation of eukaryotic translation initiation factor 2 subunit-α (EIF2S1, better known as eIF2α), the activation of autophagy, and a global arrest in transcription and translation. Here, we outline methodological approaches for measuring ICD markers in vitro and ex vivo for the discovery of next-generation antineoplastic agents, the development of personalized anticancer regimens, and the identification of optimal therapeutic combinations for the clinical management of cancer.

Tuning Cancer Fate: Tumor Microenvironment's Role in Cancer Stem Cell Quiescence and Reawakening

Cancer cell dormancy is a common feature of human tumors and represents a major clinical barrier to the long-term efficacy of anticancer therapies. Dormant cancer cells, either in primary tumors or disseminated in secondary organs, may reawaken and relapse into a more aggressive disease. The mechanisms underpinning dormancy entry and exit strongly resemble those governing cancer cell stemness and include intrinsic and contextual cues. Cellular and molecular components of the tumor microenvironment persistently interact with cancer cells. This dialog is highly dynamic, as it evolves over time and space, strongly cooperates with intrinsic cell nets, and governs cancer cell features (like quiescence and stemness) and fate (survival and outgrowth). Therefore, there is a need for deeper insight into the biology of dormant cancer (stem) cells and the mechanisms regulating the equilibrium quiescence-versus-proliferation are vital in our pursuit of new therapeutic opportunities to prevent cancer from recurring. Here, we review and discuss microenvironmental regulations of cancer dormancy and its parallels with cancer stemness, and offer insights into the therapeutic strategies adopted to prevent a lethal recurrence, by either eradicating resident dormant cancer (stem) cells or maintaining them in a dormant state.

MPA/DMBA-driven mammary carcinomas

The polycyclic aromatic hydrocarbon 7,12-dimethylbenz[a]anthracene (DMBA, D) administered per os to wild-type female mice bearing slow-release medroxyprogesterone (MPA, M) pellets s.c. drives the formation of mammary carcinomas that recapitulate numerous immunobiological features of human luminal B breast cancer. In particular, M/D-driven mammary carcinomas established in immunocompetent C57BL/6 female mice (1) express hormone receptors, (2) emerge by evading natural immunosurveillance and hence display a scarce immune infiltrate largely polarized toward immunosuppression, (3) exhibit exquisite sensitivity to CDK4/CDK6 inhibitors, and (4) are largely resistant to immunotherapy with immune checkpoint blockers targeting PD-1. Thus, M/D-driven mammary carcinomas evolving in immunocompetent female mice stand out as a privileged preclinical platform for the study of luminal B breast cancer. Here, we provide a detailed protocol for the establishment of M/D-driven mammary carcinomas in wild-type C57BL/6 female mice. This protocol can be easily adapted to generate M/D-driven mammary carcinomas in female mice with most genetic backgrounds (including genetically-engineered mice).

Immunocyte density in parathyroid carcinoma is correlated with disease relapse

PURPOSE

Parathyroid carcinoma (PC) is an endocrine malignancy with a poor prognosis. The tumour immune microenvironment is a critical factor influencing the outcomes of multiple cancer types. However, knowledge of the immune microenvironment in PC remains limited.

METHODS

The intratumoural density of immunocytes and the Ki-67 index were evaluated immunohistochemically in 51 PC patient samples and were compared with clinicopathological features and parafibromin staining results. The Kaplan-Meier method and Cox proportional hazards analysis were used to estimate the effects of these variables on clinical outcomes.

RESULTS

Intratumoural immunocyte density was not correlated with age, gender, urolithiasis, or palpation of a neck mass. The Ki-67 index was correlated with the intratumoural density of CD3⁺ cells (P = 0.022) and CD8⁺ cells (P = 0.021) and serum calcium levels (P = 0.022). In the intratumoural area of primary foci, Kaplan-Meier method showed that the risk factors associated with recurrence/metastasis were a low density of CD3⁺ (P = 0.017), CD8⁺ (P = 0.019) and CD45⁺ cells (P = 0.047), a high density of CD163⁺ cells (P = 0.003) and a high Ki-67 index (P = 0.004). Cox regression multivariate analysis revealed that CD163⁺ cell density (hazard ratio (HR) 16.19, 95% confidence interval (CI) 1.99-131.66; P = 0.009) and CD8⁺ cell density (HR 0.13, 95% CI 0.02-0.76, P = 0.024) were independent factors associated with PC relapse.

CONCLUSION

The immune microenvironment is an important factor influencing the relapse of PC. The intratumoural density of CD3⁺, CD8⁺, CD45⁺, and CD163⁺ immunocytes was correlated with disease-free survival (DFS) in patients with PC. Immunotherapy based on T lymphocytes or tumour-associated macrophages may be a promising treatment strategy.

Immunogenicity of cell death driven by immune effectors

Whether cell death caused by T lymphocytes and natural killer (NK) cells would be immunogenic per se has been a matter of intense debate. Two back-to-back papers from the Melero’s and Pardo’s groups have now resolved this conundrum, demonstrating that T and NK cell–mediated cytotoxicity represents indeed a bona fide variant of immunogenic cell death.

A brief review concerning Chimeric Antigen Receptors T cell therapy

The understanding concerning the function of immune system in cancer has achieved considerable advance with time passes by. Manipulating genetically engineered immune cells were investigated as a novel strategy for treating cancer. Chimeric antigen receptors (CARs) are recombinant protein molecules by merging the exquisite targeting the potent cytotoxicity of T cells and specificity of monoclonal antibodies and, which could trigger serial cascades of signal transduction and thereby activate T cells to directly destroy the tumor cells. Manufacturing CAR-modified T lymphocytes were successfully implemented in treating cancer derived from they could specifically retarget tumor-associated antigens, causing effective elimination of tumor cells, which spurred the optimization and development of new CAR-T cell technology. The advancement of synthetic biology methodologies of cell therapy in CAR-T would ultimately provide us with a much safer, reliable and efficient modality to against cancer. This review primarily described the emergence, development and application of cell therapy in CAR-T, then discuss the side effects and the potential factors of tumor reccurrence caused by CAR-T cell therapy, in addition to the corresponding countermeasure concerning complications.

Calreticulin and cancer

Calreticulin (CALR) is an endoplasmic reticulum (ER)-resident protein involved in a spectrum of cellular processes. In healthy cells, CALR operates as a chaperone and Ca²⁺ buffer to assist correct protein folding within the ER. Besides favoring the maintenance of cellular proteostasis, these cell-intrinsic CALR functions support Ca²⁺-dependent processes, such as adhesion and integrin signaling, and ensure normal antigen presentation on MHC Class I molecules. Moreover, cancer cells succumbing to immunogenic cell death (ICD) expose CALR on their surface, which promotes the uptake of cell corpses by professional phagocytes and ultimately supports the initiation of anticancer immunity. Thus, loss-of-function CALR mutations promote oncogenesis not only as they impair cellular homeostasis in healthy cells, but also as they compromise natural and therapy-driven immunosurveillance. However, the prognostic impact of total or membrane-exposed CALR levels appears to vary considerably with cancer type. For instance, while genetic CALR defects promote pre-neoplastic myeloproliferation, patients with myeloproliferative neoplasms bearing CALR mutations often experience improved overall survival as compared to patients bearing wild-type CALR. Here, we discuss the context-dependent impact of CALR on malignant transformation, tumor progression and response to cancer therapy.

Trial Watch: experimental TLR7/TLR8 agonists for oncological indications

Resiquimod (R848) and motolimod (VTX-2337) are second-generation experimental derivatives of imiquimod, an imidazoquinoline with immunostimulatory properties originally approved by the US Food and Drug Administration for the topical treatment of actinic keratosis and genital warts more than 20 years ago. Both resiquimod and motolimod operate as agonists of Toll-like receptor 7 (TLR7) and/or TLR8, in thus far delivering adjuvant-like signals to antigen-presenting cells (APCs). In line with such an activity, these compounds are currently investigated as immunostimulatory agents for the treatment of various malignancies, especially in combination with peptide-based, dendritic cell-based, cancer cell lysate-based, or DNA-based vaccines. Here, we summarize preclinical and clinical evidence recently collected to support the development of resiquimod and motolimod and other TLR7/TLR8 agonists as anticancer agents.

Trial watch: STING agonists in cancer therapy

Stimulator of interferon response cGAMP interactor 1 (STING1, best known as STING) is an endoplasmic reticulum-sessile protein that serves as a signaling hub, receiving input from several pattern recognition receptors, most of which sense ectopic DNA species in the cytosol. In particular, STING ensures the production of type I interferon (IFN) in response to invading DNA viruses, bacterial pathogens, as well as DNA leaking from mitochondria or the nucleus (e.g., in cells exposed to chemotherapy or radiotherapy). As a type I IFN is critical for the initiation of anticancer immune responses, the pharmaceutical industry has generated molecules that directly activate STING for use in oncological indications. Such STING agonists are being tested in clinical trials with the rationale of activating STING in tumor cells or tumor-infiltrating immune cells (including dendritic cells) to elicit immunostimulatory effects, alone or in combination with a range of established chemotherapeutic and immunotherapeutic regimens. In this Trial Watch, we discuss preclinical evidence and accumulating clinical experience shaping the design of Phase I and Phase II trials that evaluate the safety and preliminary efficacy of STING agonists in cancer patients.

Trial watch: IDO inhibitors in cancer therapy

Indoleamine 2,3-dioxygenase 1 (IDO1) catalyzes the first, rate-limiting step of the so-called “kynurenine pathway”, which converts the essential amino acid L-tryptophan (Trp) into the immunosuppressive metabolite L-kynurenine (Kyn). While expressed constitutively by some tissues, IDO1 can also be induced in specific subsets of antigen-presenting cells that ultimately favor the establishment of immune tolerance to tumor antigens. At least in part, the immunomodulatory functions of IDO1 can be explained by depletion of Trp and accumulation of Kyn and its derivatives. In animal tumor models, genetic or pharmacological IDO1 inhibition can cause the (re)activation of anticancer immune responses. Similarly, neoplasms expressing high levels of IDO1 may elude anticancer immunosurveillance. Therefore, IDO1 inhibitors represent promising therapeutic candidates for cancer therapy, and some of them have already entered clinical evaluation. Here, we summarize preclinical and clinical studies testing IDO1-targeting interventions for oncologic indications.

Trial watch: TLR3 agonists in cancer therapy

Toll-like receptor 3 (TLR3) is a pattern recognition receptor that senses exogenous (viral) as well as endogenous (mammalian) double-stranded RNA in endosomes. On activation, TLR3 initiates a signal transduction pathway that culminates with the secretion of pro-inflammatory cytokines including type I interferon (IFN). The latter is essential not only for innate immune responses to infection but also for the initiation of antigen-specific immunity against viruses and malignant cells. These aspects of TLR3 biology have supported the development of various agonists for use as stand-alone agents or combined with other therapeutic modalities in cancer patients. Here, we review recent preclinical and clinical advances in the development of TLR3 agonists for oncological disorders.

Abbreviations

cDC, conventional dendritic cell; CMT, cytokine modulating treatment; CRC, colorectal carcinoma; CTL, cytotoxic T lymphocyte; DC, dendritic cell; dsRNA, double-stranded RNA; FLT3LG, fms-related receptor tyrosine kinase 3 ligand; HNSCC, head and neck squamous cell carcinoma; IFN, interferon; IL, interleukin; ISV, in situ vaccine; MUC1, mucin 1, cell surface associated; PD-1, programmed cell death 1; PD-L1, programmed death-ligand 1; polyA:U, polyadenylic:polyuridylic acid; polyI:C, polyriboinosinic:polyribocytidylic acid; TLR, Toll-like receptor.

Immunomodulation by anticancer cell cycle inhibitors

Cell cycle proteins that are often dysregulated in malignant cells, such as cyclin-dependent kinase 4 (CDK4) and CDK6, have attracted considerable interest as potential targets for cancer therapy. In this context, multiple inhibitors of CDK4 and CDK6 have been developed, including three small molecules (palbociclib, abemaciclib and ribociclib) that are currently approved for the treatment of patients with breast cancer and are being extensively tested in individuals with other solid and haematological malignancies. Accumulating preclinical and clinical evidence indicates that the anticancer activity of CDK4/CDK6 inhibitors results not only from their ability to block the cell cycle in malignant cells but also from a range of immunostimulatory effects. In this Review, we discuss the ability of anticancer cell cycle inhibitors to modulate various immune functions in support of effective antitumour immunity.

CAR T cell therapy: newer approaches to counter resistance and cost

The genetically engineered Chimeric Antigen Receptor bearing T-cell (CAR T cell) therapy has been emerged as the new paradigm of cancer immunotherapy. However, recent studies have reported an increase in the number of relapsed haematological malignancies. This review provides newer insights into how the efficacy of CAR T cells might be increased by the application of new genome editing technologies, monitoring the complexity of tumor types and T cells sub-types. Next, tumor mutation burden along with tumormicroenvironment and epigenetic mechanisms of CAR T cell as well as tumor cell may play a vital role to tackle the cancer resistance mechanisms. These studies highlight the need to consider traditional cancer therapy in conjunction with CAR T cell therapy for relapsed or cases unresponsive to treatment. Of note, this therapy is highly expensive and requires multi-skill for successful implementation, which results in reduction of its accessibility/affordability to the patients. Here, we also propose a model for cost minimization of CAR T cell therapy by a collaboration of academia, hospitals and industry.

Computational methods in tumor immunology

The remarkable success of cancer immunotherapies, especially the checkpoint blocking antibodies, in a subset of patients has reinvigorated the study of tumor-immune crosstalk and its role in heterogeneity of response. High-throughput sequencing and imaging technologies can help recapitulate various aspects of the tumor ecosystem. Computational approaches provide an arsenal of tools to efficiently analyze, quantify and integrate multiple parameters of tumor immunity mined from these diverse but complementary high-throughput datasets. This chapter describes numerous such computational approaches in tumor immunology that leverage high-throughput data from diverse sources (genomic, transcriptomics, epigenomics and digitized histopathology images) to systematically interrogate tumor immunity in context of its microenvironment, and to identify mechanisms that confer resistance or sensitivity to cancer therapies, in particular immunotherapy.

Consensus guidelines for the definition, detection and interpretation of immunogenic cell death

Cells succumbing to stress via regulated cell death (RCD) can initiate an adaptive immune response associated with immunological memory, provided they display sufficient antigenicity and adjuvanticity. Moreover, multiple intracellular and microenvironmental features determine the propensity of RCD to drive adaptive immunity. Here, we provide an updated operational definition of immunogenic cell death (ICD), discuss the key factors that dictate the ability of dying cells to drive an adaptive immune response, summarize experimental assays that are currently available for the assessment of ICD in vitro and in vivo, and formulate guidelines for their interpretation.

Cytofluorometric assessment of dendritic cell-mediated uptake of cancer cell apoptotic bodies

Dendritic cells (DCs) are specialized antigen presenting cells (APCs) able to intake and crosspresent antigens (Ags) on major histocompatibility complex (MHC) class I and II molecules to T cells thus initiating primary and memory immune responses. DC-mediated Ag uptake and crosspresentation represent crucial steps toward cancer recognition and eventually elimination. Cytofluorometry is a standardized procedure to study phagocytosis. By fast and reproducible single cell measurements, flow cytometry allows for simultaneous biochemical and functional analyses of Ag intake. In this chapter, we discuss a two-color flow cytometric analysis of DC-mediated uptake of apoptotic bodies. We also show data on the adjuvanticity of Type-I-interferons (Type-I-IFNs) during Ag retention as we offer a guideline and a range of advice on sample preparation and acquisition.

Genomic Signatures of Immune Activation Predict Outcome in Advanced Stages of Ovarian Cancer and Basal-Like Breast Tumors

There is an unmet need for new therapies in metastatic ovarian cancer and basal-like breast cancer since no curative therapies are currently available. Immunotherapy has shown to be active in several solid tumors, but particularly more in those where a pre-activated immune state does exist. In this work, we aim to identify biomarkers that could distinguish immune-activated tumors and predict response to therapies in ovarian and basal-like breast cancer, as well as their association with the level of tumor immune infiltration. We found that the combined expression of IFNG, CD30, CXCL13, and PRF1 correlated with better overall survival (OS) in advanced stage ovarian cancer. This was confirmed using an independent dataset from TCGA. Interestingly, we observed that this gene combination also predicted for better prognosis in ovarian tumors with low mutational load, which typically respond less to immunotherapy. Expression of IFNG, CD30, CXCL13, and PRF1 was associated with increased level of immune infiltrates (CD8⁺ T cells, dendritic cells, and neutrophils) within the tumor. Moreover, we found that these gene signature also correlated with an increased OS and with a higher level of tumor immune infiltrates (B cells, CD8⁺ T cells, CD4⁺ T cells, neutrophils, and dendritic cells) in basal-like breast cancer. In conclusion, our analysis identifies genes signatures with potential to recognize immune activated ovarian and basal-like breast cancers with favorable prognosis and with a remarkable predictive capacity in tumors with low mutational burden. The presented results led to a hypothesis being formulated, but prospective clinical studies are needed to support a potential clinical application.

Trial watch: chemotherapy-induced immunogenic cell death in immuno-oncology

The term ‘immunogenic cell death’ (ICD) denotes an immunologically unique type of regulated cell death that enables, rather than suppresses, T cell-driven immune responses that are specific for antigens derived from the dying cells. The ability of ICD to elicit adaptive immunity heavily relies on the immunogenicity of dying cells, implying that such cells must encode and present antigens not covered by central tolerance (antigenicity), and deliver immunostimulatory molecules such as damage-associated molecular patterns and cytokines (adjuvanticity). Moreover, the host immune system must be equipped to detect the antigenicity and adjuvanticity of dying cells. As cancer (but not normal) cells express several antigens not covered by central tolerance, they can be driven into ICD by some therapeutic agents, including (but not limited to) chemotherapeutics of the anthracycline family, oxaliplatin and bortezomib, as well as radiation therapy. In this Trial Watch, we describe current trends in the preclinical and clinical development of ICD-eliciting chemotherapy as partner for immunotherapy, with a focus on trials assessing efficacy in the context of immunomonitoring.