Immunogenic (tum-) variants of mouse tumor P815: cloning of the gene of tum- antigen P91A and identification of the tum- mutation

Individualized Neoantigen-Directed Melanoma Therapy

Individualized neoantigen-directed therapy represents a groundbreaking approach in melanoma treatment that leverages the patient's own immune system to target cancer cells. This innovative strategy involves the identification of unique immunogenic neoantigens (mutated proteins specific to an individual's tumor) and the development of therapeutic vaccines that either consist of peptide sequences or RNA encoding these neoantigens. The goal of these therapies is to induce neoantigen-specific immune responses, enabling the immune system to recognize and destroy cancer cells presenting the targeted neoantigens. This individualized approach is particularly advantageous given the genetic heterogeneity of melanoma, which exhibits distinct mutations among different patients. In contrast to traditional therapies, neoantigen-directed therapy offers a tailored treatment that potentially reduces off-target side effects and enhances therapeutic efficacy. Recent advances in neoantigen prediction and vaccine development have facilitated clinical trials exploring the combination of neoantigen vaccines with immune checkpoint inhibitors. These trials have shown promising clinical outcomes, underscoring the potential of this personalized approach. This review provides an overview of the rationale behind neoantigen-directed therapies and summarizes the current state of knowledge regarding personalized neoantigen vaccines in melanoma treatment.

Extracellular vesicles-based vaccines: Emerging immunotherapies against cancer

Cancer vaccines are promising therapeutic approaches to enhance specific T-cell immunity against most solid tumors. By stimulating anti-tumor immunity, clearing minimal residual disease, and minimizing adverse effects, these vaccines target tumor cells and are effective when combined with immune checkpoint blockade or other immunotherapies. However, the development of tumor cell-based vaccines faces quality issues due to poor immunogenicity, tumor heterogeneity, a suppressive tumor immune microenvironment, and ineffective delivery methods. In contrast, extracellular vesicles (EVs), naturally released by cells, are considered the ideal drug carriers and vaccine platforms. EVs offer highly organ-specific targeting, induce broader and more effective immune responses, and demonstrate superior tissue delivery ability. The development of EV vaccines is crucial for advancing cancer immunotherapy. Compared to cell-based vaccines, EV vaccines produced under Good Manufacturing Practices (GMP) offer advantages such as high safety, ease of preservation and transport, and a wide range of sources. This review summarizes the latest research findings on EV vaccine and potential applications in this field. It also highlights novel neoantigens for the development of EV vaccines against cancer.

Reconfiguring the immune system to target cancer: Therapies based on T cells, cytokines, and vaccines

Over the years, extensive research has been dedicated to performing in-depth analysis of cancer to uncover the intricate details of its nature - including the types of cancer, causative agents, stimulators of disease progression, factors contributing to poor prognosis, and efficient therapies to restrict the metastatic aggressiveness. This chapter highlights the mechanisms through which different arms of the host immune system - namely cytokines, lymphocytes, antigen-presenting cells (APCs) -can be mobilized to eradicate cancer. Most malignant tumors are either poorly immunogenic, or are harbored in a highly immuno-suppressive microenvironment. This is why reinforcing the host's anti-tumor defenses, through infusion of pro-inflammatory cytokines, tumor antigen-loaded APCs, and anti-tumor cytotoxic cells has emerged as a viable treatment option against cancer. The chapter also highlights the ongoing preclinical and clinical studies in different malignancies and the outcome of various therapies. Although these methods are not foolproof, and antigen escape variants can still evade or develop resistance to customized therapies, they achieve disease stabilization in several cases when conventional treatments fail. In many instances, combination therapies involving cytokines, T cells, and vaccinations prove more effective than monotherapies. The limitations of the current therapies are also discussed, along with ongoing modifications aimed at improving efficacy.

A precision immuno-oncology turn? Hybridizing cancer genomics and immunotherapy through neoantigens-based adoptive cell therapies

This article explores the development of T cell-based therapies in Switzerland. These therapies, which elicit the immunological potential of each patient to respond to tumor development, constitute a major promise for so-called 'precision oncology'. We document how immunological concepts, technologies, and practices are articulated given the centrality of genomics in 'precision oncology'. We consider 'precision immunotherapies' to probe whether and how change ensues in these established sociotechnical regimes of biomedicine. The case of genomics and immunology in oncology offers a unique insight into the conditions of possibility for change in such regimes. How does the present new wave of cancer immunotherapies challenge, integrate, and complement the centrality of genomics in 'precision oncology'? What are the specific processes that make possible the convergence, competition, or co-existence of distinct conceptions, infrastructures, and programs of innovative cancer medicine? Drawing from observations and interviews with researchers and clinicians, we qualify these sociotechnical processes as hybridizations. Bringing together different sociotechnical regimes of biomedical research is conditional to the articulation of core concepts, technologies, and translational practices of genomics and immunology. Pivotal to this objective are neoantigens, cell surface proteins originating from the somatic genetic mutations of tumors and which activate a patient's immune response. While neoantigens are an unstable entity in experimentation, they offer a conceptual and material substrate to renegotiate the dominance of cancer genomics, and initiate the production of a new, hybrid regime of 'immunogenomic precision' in oncology.

Coley's Toxin to First Approved Therapeutic Vaccine-A Brief Historical Account in the Progression of Immunobiology-Based Cancer Treatment

Cancer immunobiology is one of the hot topics of discussion amongst researchers today, and immunotherapeutic modalities are among the selected few emerging approaches to cancer treatment that have exhibited a promising outlook. However, immunotherapy is not a new kid on the block; it has been around for centuries. The origin of cancer immunotherapy in modern medicine can be traced back to the initial reports of spontaneous regression of malignant tumors in some patients following an acute febrile infection, at the turn of the twentieth century. This review briefly revisits the historical accounts of immunotherapy, highlighting some of the significant developments in the field of cancer immunobiology, that have been instrumental in bringing back the immunotherapeutic approaches to the forefront of cancer research. Some of the topics covered are: Coley's toxin-the first immunotherapeutic; the genesis of the theory of immune surveillance; the discovery of T lymphocytes and dendritic cells and their roles; the role of tumor antigens; relevance of tumor microenvironment; the anti-tumor (therapeutic) ability of Bacillus Calmette- Guérin; Melacine-the first therapeutic vaccine engineered; theories of immunoediting and immunophenotyping of cancer; and Provenge-the first FDA-approved therapeutic vaccine. In this review, head and neck cancer has been taken as the reference tumor for narrating the progression of cancer immunobiology, particularly for highlighting the advent of immunotherapeutic agents.

Developing Vaccines in Pancreatic Adenocarcinoma: Trials and Tribulations

Pancreatic adenocarcinoma represents one of the most challenging malignancies to treat, with dismal survival rates despite advances in therapeutic modalities. Immunotherapy, particularly vaccines, has emerged as a promising strategy to harness the body's immune system in combating this aggressive cancer. This abstract reviews the trials and tribulations encountered in the development of vaccines targeting pancreatic adenocarcinoma. Key challenges include the immunosuppressive tumor microenvironment, the heterogeneity of tumor antigens, and a limited understanding of immune evasion mechanisms employed by pancreatic cancer cells. Various vaccine platforms, including peptide-based, dendritic cell-based, and viral vector-based vaccines, have been explored in preclinical and clinical settings. However, translating promising results from preclinical models to clinical efficacy has proven elusive. In recent years, mRNA vaccines have emerged as a promising immunotherapeutic strategy in the fight against various cancers, including pancreatic adenocarcinoma. We will discuss the potential applications, opportunities, and challenges associated with mRNA vaccines in pancreatic cancer treatment.

Improvement of Tumor Neoantigen Detection by High-Field Asymmetric Waveform Ion Mobility Mass Spectrometry

Cancer neoantigens have been shown to elicit cancer-specific T-cell responses and have garnered much attention for their roles in both spontaneous and therapeutically induced antitumor responses. Mass spectrometry (MS) profiling of tumor immunopeptidomes has been used, in part, to identify MHC-bound mutant neoantigen ligands. However, under standard conditions, MS-based detection of such rare but clinically relevant neoantigens is relatively insensitive, requiring 300 million cells or more. Here, to quantitatively define the minimum detectable amounts of therapeutically relevant MHC-I and MHC-II neoantigen peptides, we analyzed different dilutions of immunopeptidomes isolated from the well-characterized T3 mouse methylcholanthrene (MCA)-induced cell line by MS. Using either data-dependent acquisition or parallel reaction monitoring (PRM), we established the minimum amount of material required to detect the major T3 neoantigens in the presence or absence of high field asymmetric waveform ion mobility spectrometry (FAIMS). This analysis yielded a 14-fold enhancement of sensitivity in detecting the major T3 MHC-I neoantigen (mLama4) with FAIMS-PRM compared with PRM without FAIMS, allowing ex vivo detection of this neoantigen from an individual 100 mg T3 tumor. These findings were then extended to two other independent MCA-sarcoma lines (1956 and F244). This study demonstrates that FAIMS substantially increases the sensitivity of MS-based characterization of validated neoantigens from tumors.

The bright side of chemistry: Exploring synthetic peptide-based anticancer vaccines

The present review focuses on synthetic peptide-based vaccine strategies in the context of anticancer intervention, paying attention to critical aspects such as peptide epitope selection, adjuvant integration, and nuanced classification of synthetic peptide cancer vaccines. Within this discussion, we delve into the diverse array of synthetic peptide-based anticancer vaccines, each derived from tumor-associated antigens (TAAs), including melanoma antigen recognized by T cells 1 (Melan-A or MART-1), mucin 1 (MUC1), human epidermal growth factor receptor 2 (HER-2), tumor protein 53 (p53), human telomerase reverse transcriptase (hTERT), survivin, folate receptor (FR), cancer-testis antigen 1 (NY-ESO-1), and prostate-specific antigen (PSA). We also describe the synthetic peptide-based vaccines developed for cancers triggered by oncovirus, such as human papillomavirus (HPV), and hepatitis C virus (HCV). Additionally, the potential synergy of peptide-based vaccines with common therapeutics in cancer was considered. The last part of our discussion deals with the realm of the peptide-based vaccines delivery, highlighting its role in translating the most promising candidates into effective clinical strategies. Although this discussion does not cover all the ongoing peptide vaccine investigations, it aims at offering valuable insights into the chemical modifications and the structural complexities of anticancer peptide-based vaccines.

Induction of antigen-specific immunity by mesoporous silica nanoparticles incorporating antigen peptides

Mesoporous silica nanoparticles (MSNs) are physically and chemically stable inorganic nanomaterials that have been attracting much attention as carriers for drug delivery systems in the field of nanomedicine. In the present study, we investigated the potential of MSN vaccines that incorporate antigen peptides for use in cancer immunotherapy. In vitro experiments demonstrated that fluorescently labeled MSNs accumulated in a line of mouse dendritic cells (DC2.4 cells), where the particles localized to the cytosol. These observations could suggest that MSNs have potential for use in delivering the loaded molecules into antigen-presenting cells, thereby stimulating the host acquired immune system. In vivo experiments demonstrated prolonged survival in mice implanted with ovalbumin (OVA)-expressing lymphoma cells (E.G7-OVA cells) following subcutaneous inoculation with MSNs incorporating OVA antigen peptides. Furthermore, OVA-specific immunoglobulin G antibodies and cytotoxic T lymphocytes were detected in the serum and the spleen cells, respectively, of mice inoculated with an MSN-OVA vaccine, indicating the induction of antigen-specific responses in both the humoral and cellular immune systems. These results suggested that the MSN therapies incorporating antigen peptides may serve as novel vaccines for cancer immunotherapy.

The role of transforming growth factor-β (TGF-β) in the formation of exhausted CD8 + T cells

CD8 + T cells exert a critical role in eliminating cancers and chronic infections, and can provide long-term protective immunity. However, under the exposure of persistent antigen, CD8 + T cells can differentiate into terminally exhausted CD8 + T cells and lose the ability of immune surveillance and disease clearance. New insights into the molecular mechanisms of T-cell exhaustion suggest that it is a potential way to improve the efficacy of immunotherapy by restoring the function of exhausted CD8 + T cells. Transforming growth factor-β (TGF-β) is an important executor of immune homeostasis and tolerance, inhibiting the expansion and function of many components of the immune system. Recent studies have shown that TGF-β is one of the drivers for the development of exhausted CD8 + T cells. In this review, we summarized the role and mechanisms of TGF-β in the formation of exhausted CD8 + T cells and discussed ways to target those to ultimately enhance the efficacy of immunotherapy.

Cancer neoepitopes viewed through negative selection and peripheral tolerance: a new path to cancer vaccines

A proportion of somatic mutations in tumors create neoepitopes that can prime T cell responses that target the MHC I-neoepitope complexes on tumor cells, mediating tumor control or rejection. Despite the compelling centrality of neoepitopes to cancer immunity, we know remarkably little about what constitutes a neoepitope that can mediate tumor control in vivo and what distinguishes such a neoepitope from the vast majority of similar candidate neoepitopes that are inefficacious in vivo. Studies in mice as well as clinical trials have begun to reveal the unexpected paradoxes in this area. Because cancer neoepitopes straddle that ambiguous ground between self and non-self, some rules that are fundamental to immunology of frankly non-self antigens, such as viral or model antigens, do not appear to apply to neoepitopes. Because neoepitopes are so similar to self-epitopes, with only small changes that render them non-self, immune response to them is regulated at least partially the way immune response to self is regulated. Therefore, neoepitopes are viewed and understood here through the clarifying lens of negative thymic selection. Here, the emergent questions in the biology and clinical applications of neoepitopes are discussed critically and a mechanistic and testable framework that explains the complexity and translational potential of these wonderful antigens is proposed.

Macrophage barrier in the tumor microenvironment and potential clinical applications

The tumor microenvironment (TME) constitutes a complex microenvironment comprising a diverse array of immune cells and stromal components. Within this intricate context, tumor-associated macrophages (TAMs) exhibit notable spatial heterogeneity. This heterogeneity contributes to various facets of tumor behavior, including immune response modulation, angiogenesis, tissue remodeling, and metastatic potential. This review summarizes the spatial distribution of macrophages in both the physiological environment and the TME. Moreover, this paper explores the intricate interactions between TAMs and diverse immune cell populations (T cells, dendritic cells, neutrophils, natural killer cells, and other immune cells) within the TME. These bidirectional exchanges form a complex network of immune interactions that influence tumor immune surveillance and evasion strategies. Investigating TAM heterogeneity and its intricate interactions with different immune cell populations offers potential avenues for therapeutic interventions. Additionally, this paper discusses therapeutic strategies targeting macrophages, aiming to uncover novel approaches for immunotherapy. Video Abstract.

Recent advances in immunopeptidomic-based tumor neoantigen discovery

The role of aberrantly expressed proteins in tumors in driving immune-mediated control of cancer has been well documented for more than five decades. Today, we know that both aberrantly expressed normal proteins as well as mutant proteins (neoantigens) can function as tumor antigens in both humans and mice. Next-generation sequencing (NGS) and high-resolution mass spectrometry (MS) technologies have made significant advances since the early 2010s, enabling detection of rare but clinically relevant neoantigens recognized by T cells. MS profiling of tumor-specific immunopeptidomes remains the most direct method to identify mutant peptides bound to cellular MHC. However, the need for use of large numbers of cells or significant amounts of tumor tissue to achieve neoantigen detection has historically limited the application of MS. Newer, more sensitive MS technologies have recently demonstrated the capacities to detect neoantigens from fewer cells. Here, we highlight recent advancements in immunopeptidomics-based characterization of tumor-specific neoantigens. Various tumor antigen categories and neoantigen identification approaches are also discussed. Furthermore, we summarize recent reports that achieved successful tumor neoantigen detection by MS using a variety of starting materials, MS acquisition modes, and novel ion mobility devices.

Harnessing tumor immunogenomics: Tumor neoantigens in ovarian cancer and beyond

Ovarian cancer is a major cause of death among gynecological cancers due to its highly aggressive nature. Immunotherapy has emerged as a promising avenue for ovarian cancer treatment, offering targeted approaches with reduced off-target effects. With the advent of next-generation sequencing, it has become possible to identify genomic alterations that can serve as potential targets for immunotherapy. Furthermore, immunogenomics research has revealed the importance of genetic alterations in shaping the cancer immune responses. However, the heterogeneity of immunogenicity and the low tumor mutation burden pose challenges for neoantigen-based immunotherapies. Further research is needed to identify neoantigen-specific tumor-infiltrating lymphocytes (TIL) and establish guidelines for patient inclusion criteria in TIL-based therapy. The study of neoantigens and their implications in ovarian cancer immunotherapy holds great promise, and efforts focused on personalized treatment strategies, refined neoantigen selection, and optimized therapeutic combinations will contribute to improving patient outcomes in the future.

Neo-Antigen-Reactive T Cells Immunotherapy for Colorectal Cancer: A More Personalized Cancer Therapy Approach

Colorectal cancer (CRC) is the second most common malignancy in women and the third most frequent cancer in men. Evidence has revealed that the survival of patients with metastatic CRC is very low, between one and three years. Neoantigens are known proteins encoded by mutations in tumor cells. It is theorized that recognizing neoantigens by T cells leads to T cell activation and further antitumor responses. Neoantigen-reactive T cells (NRTs) are designed against the mentioned neoantigens expressed by tumor cells. NRTs selectively kill tumor cells without damage to non-cancerous cells. Identifying patient-specific and high immunogen neoantigens is important in NRT immunotherapy of patients with CRC. However, the main challenges are the side effects and preparation of NRTs, as well as the effectiveness of these cells in vivo. This review summarized the properties of neoantigens as well as the preparation and therapeutic outcomes of NRTs for the treatment of CRC.

Cancer cell-intrinsic mechanisms driving acquired immune tolerance

Immune evasion is a hallmark of cancer, enabling tumors to survive contact with the host immune system and evade the cycle of immune recognition and destruction. Here, we review the current understanding of the cancer cell-intrinsic factors driving immune evasion. We focus on T cells as key effectors of anti-cancer immunity and argue that cancer cells evade immune destruction by gaining control over pathways that usually serve to maintain physiological tolerance to self. Using this framework, we place recent mechanistic advances in the understanding of cancer immune evasion into broad categories of control over T cell localization, antigen recognition, and acquisition of optimal effector function. We discuss the redundancy in the pathways involved and identify knowledge gaps that must be overcome to better target immune evasion, including the need for better, routinely available tools that incorporate the growing understanding of evasion mechanisms to stratify patients for therapy and trials.

The Value of Microbes in Cancer Neoantigen Immunotherapy

Tumor neoantigens are widely used in cancer immunotherapy, and a growing body of research suggests that microbes play an important role in these neoantigen-based immunotherapeutic processes. The human body and its surrounding environment are filled with a large number of microbes that are in long-term interaction with the organism. The microbiota can modulate our immune system, help activate neoantigen-reactive T cells, and play a great role in the process of targeting tumor neoantigens for therapy. Recent studies have revealed the interconnection between microbes and neoantigens, which can cross-react with each other through molecular mimicry, providing theoretical guidance for more relevant studies. The current applications of microbes in immunotherapy against tumor neoantigens are mainly focused on cancer vaccine development and immunotherapy with immune checkpoint inhibitors. This article summarizes the related fields and suggests the importance of microbes in immunotherapy against neoantigens.

Antitumor effect of neoantigen-reactive T cells combined with PD1 inhibitor therapy in mouse lung cancer

PURPOSE

Neoantigens produced from mutations in tumors are important targets of T-cell-based immunotherapy and immune checkpoint blockade has been approved for treating multiple solid tumors. We investigated the potential benefit of adoptive neoantigen-reactive T (NRT) cells in combination with programmed cell death protein 1 inhibitor (anti-PD1) for treating lung cancer in a mouse model.

METHODS

NRT cells were prepared by co-culturing T cells and neoantigen-RNA vaccine-induced dendritic cells. Then, adoptive NRT cells in combination with anti-PD1 were administered to tumor-bearing mice. Pre- and post-therapy cytokine secretion, antitumor efficacy, and tumor microenvironment (TME) changes were determined both in vitro and in vivo.

RESULTS

We successfully generated NRT cells based on the 5 neoantigen epitopes identified in this study. NRT cells exhibited an enhanced cytotoxic phenotype in vitro and the combination therapy led to attenuated tumor growth. In addition, this combination strategy downregulated the expression of the inhibitory marker PD-1 on tumor-infiltrating T cells and promoted the trafficking of tumor-specific T cells to the tumor sites.

CONCLUSION

The adoptive transfer of NRT cells in association with anti-PD1 therapy can exert an antitumor effect on lung cancer, and is a feasible, effective, and novel immunotherapy regimen for treating solid tumors.

The landscape of T cell antigens for cancer immunotherapy

The remarkable capacity of immunotherapies to induce durable regression in some patients with metastatic cancer relies heavily on T cell recognition of tumor-presented antigens. As checkpoint-blockade therapy has limited efficacy, tumor antigens have the potential to be exploited for complementary treatments, many of which are already in clinical trials. The surge of interest in this topic has led to the expansion of the tumor antigen landscape with the emergence of new antigen categories. Nonetheless, how different antigens compare in their ability to elicit efficient and safe clinical responses remains largely unknown. Here, we review known cancer peptide antigens, their attributes and the relevant clinical data and discuss future directions.

Antigen-specific and cross-reactive T cells in protection and disease

Human T cells have a diverse T-cell receptor (TCR) repertoire that endows them with the ability to identify and defend against a broad spectrum of antigens. The universe of possible antigens that T cells may encounter, however, is even larger. To effectively surveil such a vast universe, the T-cell repertoire must adopt a high degree of cross-reactivity. Likewise, antigen-specific and cross-reactive T-cell responses play pivotal roles in both protective and pathological immune responses in numerous diseases. In this review, we explore the implications of these antigen-driven T-cell responses, with a particular focus on CD8+ T cells, using infection, neurodegeneration, and cancer as examples. We also summarize recent technological advances that facilitate high-throughput profiling of antigen-specific and cross-reactive T-cell responses experimentally, as well as computational biology approaches that predict these interactions.

Adoptive neoantigen-reactive T cell therapy: improvement strategies and current clinical researches

Neoantigens generated by non-synonymous mutations of tumor genes can induce activation of neoantigen-reactive T (NRT) cells which have the ability to resist the growth of tumors expressing specific neoantigens. Immunotherapy based on NRT cells has made preeminent achievements in melanoma and other solid tumors. The process of manufacturing NRT cells includes identification of neoantigens, preparation of neoantigen expression vectors or peptides, induction and activation of NRT cells, and analysis of functions and phenotypes. Numerous improvement strategies have been proposed to enhance the potency of NRT cells by engineering TCR, promoting infiltration of T cells and overcoming immunosuppressive factors in the tumor microenvironment. In this review, we outline the improvement of the preparation and the function assessment of NRT cells, and discuss the current status of clinical trials related to NRT cell immunotherapy.

T Cell Based Immunotherapy for Cancer: Approaches and Strategies

T cells are critical in destroying cancer cells by recognizing antigens presented by MHC molecules on cancer cells or antigen-presenting cells. Identifying and targeting cancer-specific or overexpressed self-antigens is essential for redirecting T cells against tumors, leading to tumor regression. This is achieved through the identification of mutated or overexpressed self-proteins in cancer cells, which guide the recognition of cancer cells by T-cell receptors. There are two main approaches to T cell-based immunotherapy: HLA-restricted and HLA-non-restricted Immunotherapy. Significant progress has been made in T cell-based immunotherapy over the past decade, using naturally occurring or genetically engineered T cells to target cancer antigens in hematological malignancies and solid tumors. However, limited specificity, longevity, and toxicity have limited success rates. This review provides an overview of T cells as a therapeutic tool for cancer, highlighting the advantages and future strategies for developing effective T cell cancer immunotherapy. The challenges associated with identifying T cells and their corresponding antigens, such as their low frequency, are also discussed. The review further examines the current state of T cell-based immunotherapy and potential future strategies, such as the use of combination therapy and the optimization of T cell properties, to overcome current limitations and improve clinical outcomes.

Biomaterials-assisted construction of neoantigen vaccines for personalized cancer immunotherapy

INTRODUCTION

Cancer vaccine represents a promising strategy toward personalized immunotherapy, and its therapeutic potency highly relies on the specificity of tumor antigens. Among these extensively studied tumor antigens, neoantigens, a type of short synthetic peptides derived from random somatic mutations, have been shown to be able to elicit tumor-specific antitumor immune response for tumor suppression. However, challenges remain in the efficient and safe delivery of neoantigens to antigen-presenting cells inside lymph nodes for eliciting potent and sustained antitumor immune responses. The rapid advance of biomaterials including various nanomaterials, injectable hydrogels, and macroscopic scaffolds has been found to hold great promises to facilitate the construction of efficient cancer vaccines attributing to their high loading and controllable release capacities.

AREAS COVERED

In this review, we will summarize and discuss the recent advances in the utilization of different types of biomaterials to construct neoantigen-based cancer vaccines, followed by a simple perspective on the future development of such biomaterial-assisted cancer neoantigen vaccination and personalized immunotherapy.

EXPERT OPINION

These latest progresses in biomaterial-assisted cancer vaccinations have shown great promises in boosting substantially potentiated tumor-specific antitumor immunity to suppress tumor growth, thus preventing tumor metastasis and recurrence.

Tissue-specific abundance of interferon-gamma drives regulatory T cells to restrain DC1-mediated priming of cytotoxic T cells against lung cancer

Local environmental factors influence CD8+ T cell priming in lymph nodes (LNs). Here, we sought to understand how factors unique to the tumor-draining mediastinal LN (mLN) impact CD8+ T cell responses toward lung cancer. Type 1 conventional dendritic cells (DC1s) showed a mLN-specific failure to induce robust cytotoxic T cells responses. Using regulatory T (Treg) cell depletion strategies, we found that Treg cells suppressed DC1s in a spatially coordinated manner within tissue-specific microniches within the mLN. Treg cell suppression required MHC II-dependent contact between DC1s and Treg cells. Elevated levels of IFN-γ drove differentiation Treg cells into Th1-like effector Treg cells in the mLN. In patients with cancer, Treg cell Th1 polarization, but not CD8+/Treg cell ratios, correlated with poor responses to checkpoint blockade immunotherapy. Thus, IFN-γ in the mLN skews Treg cells to be Th1-like effector Treg cells, driving their close interaction with DC1s and subsequent suppression of cytotoxic T cell responses.

Research progress of neoantigen-based dendritic cell vaccines in pancreatic cancer

The mutation of the crucial genes such as tumor suppressors or oncogenes plays an important role in the initiation and development of tumors. The non-synonymous mutations in the tumor cell genome will produce non-autologous proteins (neoantigen) to activate the immune system by activating CD4+ and CD8+ T cells. Neoantigen-based peptide vaccines have exhibited exciting therapeutic effects in treating various cancers alone or in combination with other therapeutic strategies. Furthermore, antigen-loaded DC vaccines are more powerful in inducing stronger immune responses than vaccines generated by antigens and adjuvants. Therefore, neoantigen-based dendritic cell (DC) vaccines could achieve promising effects in combating some malignant tumors. In this review, we summarized and discussed the recent research progresses of the neoantigen, neoantigen-based vaccines, and DC-based vaccine in pancreatic cancers (PCs). The combination of the neoantigen and DC-based vaccine in PC was also highlighted. Therefore, our work will provide more detailed evidence and novel opinions to promote the development of a personalized neoantigen-based DC vaccine for PC.

CAF-immune cell crosstalk and its impact in immunotherapy

Tumour cells do not exist as isolated entities. Instead, they are surrounded by a variety of cells and extracellular matrix, which form the tumour microenvironment (TME). The interaction between cancer cells and their microenvironment is increasingly acknowledged as essential in dictating the outcome of the patients. The TME includes everything that surrounds tumour cells and is often highjacked by the latter to promote their growth, invasion, and immune escape. Immune cells and cancer-associated fibroblasts (CAFs) are essential components of the TME, and there is increasing evidence that their interaction constitutes a major player not only for tumour progression but also for therapy response.

Recent work in the field of immuno-oncology resulted in the development of novel therapies that aim at activating immune cells against cancer cells to eliminate them. Despite their unprecedented success, the lack of response from a large portion of patients highlights the need for further progress and improvement. To achieve its ultimate goal, the interaction between cancer cells and the TME needs to be studied in-depth to allow the targeting of mechanisms that are involved in resistance or refractoriness to therapy. Moreover, predictive and prognostic biomarkers for patient stratification are still missing. In this review, we focus on and highlight the complexity of CAFs within the TME and how their interaction, particularly with immune cells, can contribute to treatment failure. We further discuss how this crosstalk can be further dissected and which strategies are currently used to target them.

Impact of cancer evolution on immune surveillance and checkpoint inhibitor response

Intratumour heterogeneity (ITH) is pervasive across all cancers studied and may provide the evolving tumour multiple routes to escape immune surveillance. Immune checkpoint inhibitors (CPIs) are rapidly becoming standard of care for many cancers. Here, we discuss recent work investigating the influence of ITH on patient response to immune checkpoint inhibitor (CPI) therapy. At its simplest, ITH may confound the diagnostic accuracy of predictive biomarkers used to stratify patients for CPI therapy. Furthermore, ITH is fuelled by mechanisms of genetic instability that can both engage immune surveillance and drive immune evasion. A greater appreciation of the interplay between ITH and the immune system may hold the key to increasing the proportion of patients experiencing durable responses from CPI therapy.

Harnessing gene fusion-derived neoantigens for 'cold' breast and prostate tumor immunotherapy

Breast and prostate cancers are generally considered immunologically 'cold' tumors due to multiple mechanisms rendering them unresponsive to immune checkpoint blockade therapies. With little success in garnering positive outcomes in modern immunotherapeutic clinical trials, it is prudent to re-examine the role of immunogenic neoantigens in these cold tumors. Gene fusions are driver mutations in hormone-driven cancers that can result in alternative mutation-specific neoantigens to promote immunotherapy sensitivity. This review focuses on 1) gene fusion formation mechanisms in neoantigen generation; 2) gene fusion neoantigens in cancer immunotherapeutic strategies and associated clinical trials; and 3) challenges and opportunities in computational and liquid biopsy technologies. This review is anticipated to initiate further research into gene fusion neoantigens of cold tumors for further experimental validation.

Neoantigen vaccine and neoantigen-specific cell adoptive transfer therapy in solid tumors: Challenges and future directions

The phenomenon of tumor hierarchy and genetic instability can be explained by the "two-hits theory" and results in the occurrence of many somatic mutations. The expression of nonsynonymous mutations results in the production of mutant proteins from tumor cells, namely tumor-specific antigens called neoantigens. Because neoantigens do not exist in healthy cells, they have the potential to stimulate antitumor immune responses by CD4+ and CD8+ T-cell activation without jeopardizing normal tissues. Immunotherapy has reshaped the cancer treatment paradigm in recent decades with the introduction of immune-checkpoint blockade therapy and transgenic T-cell receptor/chimeric antigen receptor T cells. However, these strategies performed poorly in solid tumors because of the obstacles of the immunosuppressive microenvironment caused by regulatory T cells and other suppressor cells. Therefore, other immunotherapeutic strategies are under development, such as personalized vaccines, to trigger de novo T-cell responses against neoantigens and lead to the amplification of tumor-specific T-cell subclones. Neoantigen epitope prediction algorithms have enabled the detection of neoantigens and the creation of tailored neoantigen vaccines as a result of the fast development of next-generation sequencing and cancer bioinformatics. Here we provide an overview of the current neoantigen cancer vaccines and adoptive T-cell transfer therapy with neoantigen-specific lymphocytes. We also discuss the challenges in developing neoantigen-targeted immunotherapeutic strategies for cancer.

Neoantigens in precision cancer immunotherapy: from identification to clinical applications

Immunotherapies targeting cancer neoantigens are safe, effective, and precise. Neoantigens can be identified mainly by genomic techniques such as next-generation sequencing and high-throughput single-cell sequencing; proteomic techniques such as mass spectrometry; and bioinformatics tools based on high-throughput sequencing data, mass spectrometry data, and biological databases. Neoantigen-related therapies are widely used in clinical practice and include neoantigen vaccines, neoantigen-specific CD8+ and CD4+ T cells, and neoantigen-pulsed dendritic cells. In addition, neoantigens can be used as biomarkers to assess immunotherapy response, resistance, and prognosis. Therapies based on neoantigens are an important and promising branch of cancer immunotherapy. Unremitting efforts are needed to unravel the comprehensive role of neoantigens in anti-tumor immunity and to extend their clinical application. This review aimed to summarize the progress in neoantigen research and to discuss its opportunities and challenges in precision cancer immunotherapy.

Identification of neoantigens for individualized therapeutic cancer vaccines

Somatic mutations in cancer cells can generate tumour-specific neoepitopes, which are recognized by autologous T cells in the host. As neoepitopes are not subject to central immune tolerance and are not expressed in healthy tissues, they are attractive targets for therapeutic cancer vaccines. Because the vast majority of cancer mutations are unique to the individual patient, harnessing the full potential of this rich source of targets requires individualized treatment approaches. Many computational algorithms and machine-learning tools have been developed to identify mutations in sequence data, to prioritize those that are more likely to be recognized by T cells and to design tailored vaccines for every patient. In this Review, we fill the gaps between the understanding of basic mechanisms of T cell recognition of neoantigens and the computational approaches for discovery of somatic mutations and neoantigen prediction for cancer immunotherapy. We present a new classification of neoantigens, distinguishing between guarding, restrained and ignored neoantigens, based on how they confer proficient antitumour immunity in a given clinical context. Such context-based differentiation will contribute to a framework that connects neoantigen biology to the clinical setting and medical peculiarities of cancer, and will enable future neoantigen-based therapies to provide greater clinical benefit.

CD8+ T cell differentiation and dysfunction in cancer

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

Neoantigens and their potential applications in tumor immunotherapy

The incidence of malignant tumors is increasing, the majority of which are associated with high morbidity and mortality rates worldwide. The traditional treatment method for malignant tumors is surgery, coupled with radiotherapy or chemotherapy. However, these therapeutic strategies are frequently accompanied with adverse side effects. Over recent decades, tumor immunotherapy shown promise in demonstrating notable efficacy for the treatment of cancer. With the development of sequencing technology and bioinformatics algorithms, neoantigens have become compelling targets for cancer immunotherapy due to high levels of immunogenicity. In addition, neoantigen-based vaccines have demonstrated potential for cancer therapy, primarily by augmenting T-cell responses. Neoantigens have also been shown to be effective in immune checkpoint blockade therapy. Therefore, neoantigens may serve to be predictive biomarkers and synergistic treatment targets in cancer immunotherapy. The aim of the present review was to provide an overview of the recent progress in the classification, screening and clinical application of neoantigens for cancer therapy.

Role of purinergic system and vitamin D in the anti-cancer immune response

For several years, scientists have recognized that vitamin D plays an important role in mineral and bone homeostasis. It was mostly used to treat osteoporosis and rickets in the past decades. Vitamin D has also been discovered to be modulator of the immune system and may play a role in a variety of diseases, including autoimmune diseases, in recent years. Vitamin D interaction with the vitamin D receptor (VDR), which has transcriptional imparts and is displayed on a variety of cell types, including those of the immune system, appears to be accountable for the immune-modulating effects. The action of tumor cells and vitamin D were the first to be investigated, but the spotlight is now on immunologic and purinergic systems. We conducted a systematic search in Pub Med as well as Google scholar for studies written in English. Vitamin D, cancer, purinergic signaling, and immune response were among the search words. Vitamin D has the potential to be a useful coadjuvant in cancer therapy and the purinergic system may be a potential treatment target to cancer therapy, according to our findings.

The Role of Neoantigens in Cancer Immunotherapy

Somatic mutation-derived neoantigens, expressed only on tumor cells, may elicit antitumor T-cell responses in cancer immunotherapies with minimal immune tolerance. Neoantigens can be identified by multiple bioinformatics technologies, mainly based on whole-exome sequencing. Personalized cancer vaccines and adoptive T cell therapies are two primary treatment modalities targeting neoantigens, and both of them have shown promising therapeutic effects. This review, summarizes the history of neoantigen-related tumor control, introduces recent neoantigen screening and identification methods, and discusses the role of neoantigen in cancer immunotherapies. Moreover, we propose the challenges of targeting neoantigens for cancer treatment.

Immunobiology of Melanoma

Despite the ability of immune-based interventions to dramatically increase the survival of patients with melanoma, a significant subset fail to benefit from this treatment, underscoring the need for accurate means to identify the patient population likely to respond to immunotherapy. Understanding how melanoma evades natural or manipulated immune responses could provide the information needed to identify such resistant individuals. Efforts to address this challenge are hampered by the vast immune diversity characterizing tumor microenvironments that remain largely understudied. It is thus important to more clearly elucidate the complex interactions that take place between the tumor microenvironment and host immune system.

Identification and Targeting of Mutant Peptide Neoantigens in Cancer Immunotherapy

In recent decades, adoptive cell transfer and checkpoint blockade therapies have revolutionized immunotherapeutic approaches to cancer treatment. Advances in whole exome/genome sequencing and bioinformatic detection of tumour-specific genetic variations and the amino acid sequence alterations they induce have revealed that T cell mediated anti-tumour immunity is substantially directed at mutated peptide sequences, and the identification and therapeutic targeting of patient-specific mutated peptide antigens now represents an exciting and rapidly progressing frontier of personalized medicine in the treatment of cancer. This review outlines the historical identification and validation of mutated peptide neoantigens as a target of the immune system, and the technical development of bioinformatic and experimental strategies for detecting, confirming and prioritizing both patient-specific or "private" and frequently occurring, shared "public" neoantigenic targets. Further, we examine the range of therapeutic modalities that have demonstrated preclinical and clinical anti-tumour efficacy through specifically targeting neoantigens, including adoptive T cell transfer, checkpoint blockade and neoantigen vaccination.

Personalized immunotherapy in cancer precision medicine

With the significant advances in cancer genomics using next-generation sequencing technologies, genomic and molecular profiling-based precision medicine is used as a part of routine clinical test for guiding and selecting the most appropriate treatments for individual cancer patients. Although many molecular-targeted therapies for a number of actionable genomic alterations have been developed, the clinical application of such information is still limited to a small proportion of cancer patients. In this review, we summarize the current status of personalized drug selection based on genomic and molecular profiling and highlight the challenges how we can further utilize the individual genomic information. Cancer immunotherapies, including immune checkpoint inhibitors, would be one of the potential approaches to apply the results of genomic sequencing most effectively. Highly cancer-specific antigens derived from somatic mutations, the so-called neoantigens, occurring in individual cancers have been in focus recently. Cancer immunotherapies, which target neoantigens, could lead to a precise treatment for cancer patients, despite the challenge in accurately predicting neoantigens that can induce cytotoxic T cells in individual patients. Precise prediction of neoantigens should accelerate the development of personalized immunotherapy including cancer vaccines and T-cell receptor-engineered T-cell therapy for a broader range of cancer patients.

Personalized Neoantigen-Pulsed DC Vaccines: Advances in Clinical Applications

In the past few decades, great progress has been made in the clinical application of dendritic cell (DC) vaccines loaded with personalized neoantigens. Personalized neoantigens are antigens arising from somatic mutations in cancers, with specificity to each patient. DC vaccines work based on the fundamental characteristics of DCs, which are professional antigen-presenting cells (APCs), responsible for the uptake, processing, and presentation of antigens to T cells to activate immune responses. Neoantigens can exert their antitumor effects only after they are taken up by APCs and presented to T cells. In recent years, neoantigen-based personalized tumor therapeutic vaccines have proven to be safe, immunogenic and feasible treatment strategies in patients with melanoma and glioblastoma that provide new hope in the treatment of cancer patients and a new approach to cure cancer. In addition, according to ClinicalTrials.gov, hundreds of registered DC vaccine trials are either completed or ongoing worldwide, of which 9 are in early phase I, 191 in phase I, 166 in phase II and 8 in phase III. Hundreds of clinical studies on therapeutic tumor vaccines globally have proven that DC vaccines are stable, reliable and very safe. However, in this process, many other factors still limit the effectiveness of the vaccine. This review will focus on the current research progress on personalized neoantigen-pulsed DC vaccines, their limitations and future research directions of DC vaccines loaded with neoantigens. This review aims to provide a better understanding of DCs biology and manipulation of activated DCs for DCs researchers to produce the next generation of highly efficient cancer vaccines for patients.

Challenges targeting cancer neoantigens in 2021: a systematic literature review

Introduction: Cancer neoantigens represent important targets of cancer immunotherapy. The goal of cancer neoantigen vaccines is to induce neoantigen-specific immune responses and antitumor immunity while minimizing the potential for autoimmune toxicity. Advances in sequencing technologies, neoantigen prediction algorithms, and other technologies have dramatically improved the ability to identify and prioritize cancer neoantigens. Unfortunately, results from preclinical studies and early phase clinical trials highlight important challenges to the successful clinical translation of neoantigen cancer vaccines.Areas covered: In this review, we provide an overview of current strategies for the identification and prioritization of cancer neoantigens with a particular emphasis on the two most common strategies used for neoantigen identification: (1) direct identification of peptide ligands eluted from peptide-MHC complexes, and (2) next-generation sequencing combined with neoantigen prediction algorithms. We highlight the limitations of current neoantigen prediction pipelines, and discuss broader challenges associated with cancer neoantigen vaccines including tumor purity/heterogeneity and the immunosuppressive tumor microenvironment.Expert opinion: Despite current limitations, neoantigen prediction is likely to improve rapidly based on advances in sequencing, machine learning, and information sharing. The successful development of robust cancer neoantigen prediction strategies is likely to have a significant impact, with the potential to facilitate cancer neoantigen vaccine design.

Evolution of Cancer Vaccines-Challenges, Achievements, and Future Directions

The development of cancer vaccines has been intensively pursued over the past 50 years with modest success. However, recent advancements in the fields of genetics, molecular biology, biochemistry, and immunology have renewed interest in these immunotherapies and allowed the development of promising cancer vaccine candidates. Numerous clinical trials testing the response evoked by tumour antigens, differing in origin and nature, have shed light on the desirable target characteristics capable of inducing strong tumour-specific non-toxic responses with increased potential to bring clinical benefit to patients. Novel delivery methods, ranging from a patient’s autologous dendritic cells to liposome nanoparticles, have exponentially increased the abundance and exposure of the antigenic payloads. Furthermore, growing knowledge of the mechanisms by which tumours evade the immune response has led to new approaches to reverse these roadblocks and to re-invigorate previously suppressed anti-tumour surveillance. The use of new drugs in combination with antigen-based therapies is highly targeted and may represent the future of cancer vaccines. In this review, we address the main antigens and delivery methods used to develop cancer vaccines, their clinical outcomes, and the new directions that the vaccine immunotherapy field is taking.

Enhancing the Efficacy of Tumor Vaccines Based on Immune Evasion Mechanisms

Tumor vaccines aim to expand tumor-specific T cells and reactivate existing tumor-specific T cells that are in a dormant or unresponsive state. As such, there is growing interest in improving the durable anti-tumor activity of tumor vaccines. Failure of vaccine-activated T cells to protect against tumors is thought to be the result of the immune escape mechanisms of tumor cells and the intricate immunosuppressive tumor microenvironment. In this review, we discuss how tumor cells and the tumor microenvironment influence the effects of tumor infiltrating lymphocytes and summarize how to improve the efficacy of tumor vaccines by improving the design of current tumor vaccines and combining tumor vaccines with other therapies, such as metabolic therapy, immune checkpoint blockade immunotherapy and epigenetic therapy.

Cancer Vaccines: Antigen Selection Strategy

Unlike traditional cancer therapies, cancer vaccines (CVs) harness a high specificity of the host’s immunity to kill tumor cells. CVs can train and bolster the patient’s immune system to recognize and eliminate malignant cells by enhancing immune cells’ identification of antigens expressed on cancer cells. Various features of antigens like immunogenicity and avidity influence the efficacy of CVs. Therefore, the choice and application of antigens play a critical role in establishing and developing CVs. Tumor-associated antigens (TAAs), a group of proteins expressed at elevated levels in tumor cells but lower levels in healthy normal cells, have been well-studied and developed in CVs. However, immunological tolerance, HLA restriction, and adverse events are major obstacles that threaten TAA-based CVs’ efficacy due to the “self-protein” characteristic of TAAs. As “abnormal proteins” that are completely absent from normal cells, tumor-specific antigens (TSAs) can trigger a robust immune response against tumor cells with high specificity and without going through central tolerance, contributing to cancer vaccine development feasibility. In this review, we focus on the unique features of TAAs and TSAs and their application in vaccines, summarizing their performance in preclinical and clinical trials.

Neo-Antigen mRNA Vaccines

The interest in therapeutic cancer vaccines has caught enormous attention in recent years due to several breakthroughs in cancer research, among which the finding that successful checkpoint blockade treatments reinvigorate neo-antigen-specific T cells and that successful adoptive cell therapies are directed towards neo-antigens. Neo-antigens are cancer-specific antigens, which develop from somatic mutations in the cancer cell genome that can be highly immunogenic and are not subjected to central tolerance. As the majority of neo-antigens are unique to each patient's cancer, a vaccine technology that is flexible and potent is required to develop personalized neo-antigen vaccines. In vitro transcribed mRNA is such a technology platform and has been evaluated for delivery of neo-antigens to professional antigen-presenting cells both ex vivo and in vivo. In addition, strategies that support the activity of T cells in the tumor microenvironment have been developed. These represent a unique opportunity to ensure durable T cell activity upon vaccination. Here, we comprehensively review recent progress in mRNA-based neo-antigen vaccines, summarizing critical milestones that made it possible to bring the promise of therapeutic cancer vaccines within reach.

Emerging Prospects of Exosomes for Cancer Treatment: From Conventional Therapy to Immunotherapy

Exosomes are a class of extracellular vesicles of around 100 nm in diameter that are secreted by most cells and contain various bioactive molecules reflecting their cellular origin and mediate intercellular communication. Studies of these exosomal features in tumor pathogenesis have led to the development of therapeutic and diagnostic approaches using exosomes for cancer therapy. Exosomes have many advantages for conveying therapeutic agents such as small interfering RNAs, microRNAs, membrane-associated proteins, and chemotherapeutic compounds; thus, they are considered a prime candidate as a delivery tool for cancer treatment. Since exosomes also provide an optimal microenvironment for the effective function of immunomodulatory factors, exosomes harboring bioactive molecules have been bioengineered as cancer immunotherapies that can effectively activate each stage of the cancer immunity cycle to successfully elicit cancer-specific immunity. This review discusses the advantages of exosomes for treating cancer and the challenges that must be overcome for their successful clinical development.

Landscape of active enhancers developed de novo in cirrhosis and conserved in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) patients always have a background of cirrhosis. Aberrant epigenetic changes in cirrhosis provide a conductive environment for HCC tumorigenesis. Active enhancers (AEs) are essential for epigenetic regulation and play an important role in cell development and the progression of many diseases. However, the role of AEs in the progression from cirrhosis to HCC remains unclear. We systemically constructed a landscape of AEs that developed de novo in cirrhosis and were conserved in HCC, referred to as CL-HCC AEs. We observed significant upregulation of these CL-HCC AE-associated genes in cirrhosis and HCC, with no other epigenetic changes. Enrichment analysis of these CL-HCC AE-associated genes revealed enrichment in both hepatocyte-intrinsic tumorigenesis and tumor immune response, which might contribute to HCC tumorigenesis. Analysis of the diagnostic ability of these CL-HCC AE-associated genes provided a five-gene (THBS4, OLFML2B, CDKN3, GABRE, and HDAC11) diagnostic biomarker for HCC. Molecular subtype (MS) identification based on the CL-HCC AE-associated genes identified 3 MSs. Samples representing the 3 MSs showed differences in CL-HCC AE-associated gene expression levels, prognosis, copy number variation (CNV)/mutation frequencies, functional pathways, tumor microenvironment (TME) cell subtypes, immunotherapy responses and putative drug responses. We also found that the BET bromodomain inhibitor JQ1 downregulated the expression of CL-HCC AE-associated genes. Collectively, our results suggest that CL-HCC AEs and their associated genes contribute to HCC tumorigenesis and evolution, and could be used to distinguish the different landscapes of HCC and help explore the mechanism, classification, prediction, and precision therapy of HCC.

Progress in Neoantigen Targeted Cancer Immunotherapies

Immunotherapies that harness the immune system to kill cancer cells have showed significant therapeutic efficacy in many human malignancies. A growing number of studies have highlighted the relevance of neoantigens in recognizing cancer cells by intrinsic T cells. Cancer neoantigens are a direct consequence of somatic mutations presenting on the surface of individual cancer cells. Neoantigens are fully cancer-specific and exempt from central tolerance. In addition, neoantigens are important targets for checkpoint blockade therapy. Recently, technological innovations have made neoantigen discovery possible in a variety of malignancies, thus providing an impetus to develop novel immunotherapies that selectively enhance T cell reactivity for the destruction of cancer cells while leaving normal tissues unharmed. In this review, we aim to introduce the methods of the identification of neoantigens, the mutational patterns of human cancers, related clinical trials, neoantigen burden and sensitivity to immune checkpoint blockade. Moreover, we focus on relevant challenges of targeting neoantigens for cancer treatment.

Shared neoantigens: ideal targets for off-the-shelf cancer immunotherapy

Neoantigen, as an important member of tumor-specific antigens, has attracted a great deal of attention as a target for immunotherapy. Neoantigens are potential targets for personalized vaccines and adoptive cell transfer therapies. However, most of the neoantigen-targeted immunotherapies in the process are customized and costly. So, we are inclined to find shared neoantigens suitable for more patients. With the help of existing neoantigen prediction algorithms, we found that the most frequent shared neoantigens occurred in more than 1% of patients for 17 tumor types and the ten most frequent shared neoantigens covered approximately 50% of pancreatic cancer patients, providing a potential list of targets for off-the-shelf immunotherapy.