Toxicities Associated With Adoptive T-Cell Transfer for Cancer

Recent clinical researches and technological development in TIL therapy

Tumor-infiltrating lymphocyte (TIL) therapy represents a groundbreaking advancement in the solid cancer treatment, offering new hope to patients and their families with high response rates and long overall survival. TIL therapy involves extracting immune cells from a patient's tumor tissue, expanding them ex vivo, and infusing them back into the patient to target and eliminate cancer cells. This revolutionary approach harnesses the power of the immune system to combat cancers, ushering in a new era of T cell-based therapies along with CAR-T and TCR-therapies. In this comprehensive review, we aim to elucidate the remarkable potential of TIL therapy by delving into recent advancements in basic and clinical researches. We highlight on the evolving landscape of TIL therapy as a prominent immunotherapeutic strategy, its multifaceted applications, and the promising outcomes. Additionally, we explore the future horizons of TIL therapy, next-generation TILs, and combination therapy, to overcome the limitations and improve clinical efficacy of TIL therapy.

Engineered Bio-Based Hydrogels for Cancer Immunotherapy

Immunotherapy represents a revolutionary paradigm in cancer management, showcasing its potential to impede tumor metastasis and recurrence. Nonetheless, challenges including limited therapeutic efficacy and severe immune-related side effects are frequently encountered, especially in solid tumors. Hydrogels, a class of versatile materials featuring well-hydrated structures widely used in biomedicine, offer a promising platform for encapsulating and releasing small molecule drugs, biomacromolecules, and cells in a controlled manner. Immunomodulatory hydrogels present a unique capability for augmenting immune activation and mitigating systemic toxicity through encapsulation of multiple components and localized administration. Notably, hydrogels based on biopolymers have gained significant interest owing to their biocompatibility, environmental friendliness, and ease of production. This review delves into the recent advances in bio-based hydrogels in cancer immunotherapy and synergistic combinatorial approaches, highlighting their diverse applications. It is anticipated that this review will guide the rational design of hydrogels in the field of cancer immunotherapy, fostering clinical translation and ultimately benefiting patients.

A replicating LCMV-based vaccine for the treatment of solid tumors

Harnessing the immune system to eradicate tumors requires identification and targeting of tumor antigens, including tumor-specific neoantigens and tumor-associated self-antigens. Tumor-associated antigens are subject to existing immune tolerance, which must be overcome by immunotherapies. Despite many novel immunotherapies reaching clinical trials, inducing self-antigen-specific immune responses remains challenging. Here, we systematically investigate viral-vector-based cancer vaccines encoding a tumor-associated self-antigen (TRP2) for the treatment of established melanomas in preclinical mouse models, alone or in combination with adoptive T cell therapy. We reveal that, unlike foreign antigens, tumor-associated antigens require replication of lymphocytic choriomeningitis virus (LCMV)-based vectors to break tolerance and induce effective antigen-specific CD8+ T cell responses. Immunization with a replicating LCMV vector leads to complete tumor rejection when combined with adoptive TRP2-specific T cell transfer. Importantly, immunization with replicating vectors leads to extended antigen persistence in secondary lymphoid organs, resulting in efficient T cell priming, which renders previously "cold" tumors open to immune infiltration and reprograms the tumor microenvironment to "hot." Our findings have important implications for the design of next-generation immunotherapies targeting solid cancers utilizing viral vectors and adoptive cell transfer.

Engineering Challenges and Opportunities in Autologous Cellular Cancer Immunotherapy

The use of a patient's own immune or tumor cells, manipulated ex vivo, enables Ag- or patient-specific immunotherapy. Despite some clinical successes, there remain significant barriers to efficacy, broad patient population applicability, and safety. Immunotherapies that target specific tumor Ags, such as chimeric Ag receptor T cells and some dendritic cell vaccines, can mount robust immune responses against immunodominant Ags, but evolving tumor heterogeneity and antigenic downregulation can drive resistance. In contrast, whole tumor cell vaccines and tumor lysate-loaded dendritic cell vaccines target the patient's unique tumor antigenic repertoire without prior neoantigen selection; however, efficacy can be weak when lower-affinity clones dominate the T cell pool. Chimeric Ag receptor T cell and tumor-infiltrating lymphocyte therapies additionally face challenges related to genetic modification, T cell exhaustion, and immunotoxicity. In this review, we highlight some engineering approaches and opportunities to these challenges among four classes of autologous cell therapies.

New therapeutics for soft tissue sarcomas: Overview of current immunotherapy and future directions of soft tissue sarcomas

Soft tissue sarcoma is a rare and aggressive disease with a 40 to 50% metastasis rate. The limited efficacy of traditional approaches with surgery, radiation, and chemotherapy has prompted research in novel immunotherapy for soft tissue sarcoma. Immune checkpoint inhibitors such as anti-CTLA-4 and PD-1 therapies in STS have demonstrated histologic-specific responses. Some combinations of immunotherapy with chemotherapy, TKI, and radiation were effective. STS is considered a ‘cold’, non-inflamed tumor. Adoptive cell therapies are actively investigated in STS to enhance immune response. Genetically modified T-cell receptor therapy targeting cancer testis antigens such as NY-ESO-1 and MAGE-A4 demonstrated durable responses, especially in synovial sarcoma. Two early HER2-CAR T-cell trials have achieved stable disease in some patients. In the future, CAR-T cell therapies will find more specific targets in STS with a reliable response. Early recognition of T-cell induced cytokine release syndrome is crucial, which can be alleviated by immunosuppression such as steroids. Further understanding of the immune subtypes and biomarkers will promote the advancement of soft tissue sarcoma treatment.

Immunotherapy for Soft Tissue Sarcomas: Anti-PD1/PDL1 and Beyond

Sarcomas gather a heterogeneous group of mesenchymal malignant tumors including more than 150 different subtypes. Most of them represent aggressive tumors with poor prognosis at the advanced stage, despite the better molecular characterization of these tumors and the development of molecular-driven therapeutic strategies. During the last decade, immunotherapy has been developed to treat advanced cancers, mainly thanks to immune checkpoint inhibitors (ICI) such as anti-PD1/PDL1 and later to adoptive immune cell therapies. In this review, we aim to summarize the state of the art of immunotherapy in soft tissue sarcomas (STS). Overall, the clinical trials of ICI that included a wide diversity of STS subtypes reported limited efficacy with some outlying responders. Both emerging biomarkers are of interest in selecting good candidates and in the development of combination therapies. Finally, the recent breakthroughs of innovative adoptive therapies in STS seem highly promising.

Cell Immunotherapy against Melanoma: Clinical Trials Review

Melanoma is one of the most aggressive and therapy-resistant types of cancer, the incidence rate of which grows every year. However, conventional methods of chemo- and radiotherapy do not allow for completely removing neoplasm, resulting in local, regional, and distant relapses. In this case, adjuvant therapy can be used to reduce the risk of recurrence. One of the types of maintenance cancer therapy is cell-based immunotherapy, in which immune cells, such as T-cells, NKT-cells, B cells, NK cells, macrophages, and dendritic cells are used to recognize and mobilize the immune system to kill cancer cells. These cells can be isolated from the patient's peripheral blood or biopsy material and genetically modified, cultured ex vivo, following infusion back into the patient for powerful induction of an anti-tumor immune response. In this review, the advantages and problems of the most relevant methods of cell-based therapy and ongoing clinical trials of adjuvant therapy of melanoma are discussed.

Immunotherapy in Sarcoma: Where Do Things Stand?

Early experiences with modern immunotherapy have been disappointing in trials of unselected sarcoma subtypes. However, remarkable efficacy has been observed with immune checkpoint inhibitors (ICIs) in a subset of patients, with the most promising outcomes to date in alveolar soft part sarcoma, cutaneous angiosarcoma, undifferentiated pleomorphic sarcoma (UPS), and dedifferentiated liposarcoma (dLPS). Adoptive cellular therapies targeting cancer testis antigens have shown promising activity, but only synovial sarcoma (SS) and myxoid/round cell liposarcomas reliably express these targets. The majority of sarcomas are immunologically "cold" with sparse immune infiltration, which may explain the poor response to immunotherapy. Current immunotherapy trials for sarcomas explore combination therapies with checkpoint inhibitors to overcome immune evasion and novel targets in adoptive cellular therapies. The role of tertiary lymphoid structures, PD-L1 expression, tumor mutational burden, microsatellite instability, and tumor lymphocytes as biomarkers for response are areas of active investigation. In this review, we highlight prior and ongoing clinical efforts to improve outcomes with immunotherapy and discuss the current state of understanding for biomarkers to select patients most likely to benefit from this approach.

Phase I study of adjuvant immunotherapy with autologous tumor-infiltrating lymphocytes in locally advanced cervical cancer

BACKGROUND

Adoptive cell therapy (ACT) with tumor-infiltrating lymphocytes (TILs) has achieved remarkable clinical efficacy in metastatic cancers such as melanoma and cervical cancer (CC). Here we explored the safety, feasibility and preliminary tumor response and performed translational investigations of adjuvant immunotherapy using infusion of autogenous (auto)-TILs following concurrent chemoradiotherapy (CCRT) in CC patients with locally advanced disease.

METHODS

Twenty-seven CC patients with stage III to IV disease were recruited in this single-center, phase I study. TILs were isolated from lesions in the uterine cervix and generated under good manufacturing practices (GMP) conditions and then infused after CCRT plus intramuscular interleukin (IL)-2 injections.

RESTULTS

From 27 patients, TILs were successfully expanded from 20 patients, with a feasibility of 74.1%. Twelve patients received TILs following CCRT. Adverse events (AEs) were primarily attributable to CCRT. Only 1 (8.3%) patient experienced severe toxicity with a grade 3 hypersensitivity reaction after TIL infusion. No autoimmune AEs, such as pneumonitis, hepatitis, or myocarditis, occurred, and there was no treatment-related mortality. Nine of 12 patients (75.0%) attained complete response, with a disease control duration of 9 to 22 months. Translational investigation showed that the transcriptomic characteristics of the infused TIL products and some immune biomarkers in the tumor microenvironment and serum of CC patients at baseline were correlated with the clinical response.

CONCULSION

TIL-based ACT following CCRT was safe in an academic center setting, with potential effective responses in locally advanced CC patients. 'Hot' inflammatory immune environments are beneficial to the clinical efficacy of TIL-based ACT as adjuvant therapy.

TRIAL REGISTRATION

CLINICALTRIALS

gov NCT04443296.

FUNDING

Natinoal Key R&D Program: Sci-Tech Key Program of the Guangzhou City Science Foundation; the Guangdong Provinve Sci-Tech International Key Program; the National Natural Science Foundation of China.

Tumor-infiltrating lymphocytes for adoptive cell therapy: recent advances, challenges, and future directions

INTRODUCTION

Adoptive cell therapy (ACT) with tumor-infiltrating lymphocytes (TILs) is a highly personalized type of cancer immunotherapy. TIL-based ACT exploits naturally occurring TILs, derived from the patients' tumor. This treatment has shown consistent clinical responses in melanoma, and recent results point toward a potential use in multiple cancer diagnoses. However, several limitations have restricted the clinical development and adaptation of TIL-based ACT.

AREAS COVERED

In this review, we present the principles of TIL-based ACT and discuss the most significant limitations for therapeutic efficacy and its widespread application. The topics of therapeutic resistance (both innate and acquired), treatment-related toxicity, and the novel research topic of metabolic barriers in the tumor microenvironment (TME) are covered.

EXPERT OPINION

There are many ongoing areas of research focusing on improving clinical efficacy and optimizing TIL-based ACT. Many strategies have shown great potential, particularly strategies advancing TIL efficacy (such as increasing and harnessing ex vivo the sub-population of tumor-reactive TILs) and manufacturing processes. Novel approaches can help overcome current limitations and potentially result in TIL-based ACT entering the mainstream of cancer therapy across tumor types.

A Dual Functional Drug Delivery System that Combines Photothermal Therapy and Immunotherapy to Treat Tumors

Cancer is one of the main diseases threatening human health. Immunotherapy, in which cancer is treated by activating immune cells and inducing the body's immune response, has rapidly developed. Photothermal therapy (PTT), a new treatment method that ablates tumors by light irradiation, has attracted great attention for its good therapeutic effect and low toxic side effects. In the present study, we combined photothermal and immunotherapy to design a novel nanoparticle delivery system by loading indoleamine 2,3-dioxygenase (IDO) inhibitors and toll-like receptor (TLR) agonists into polydopamine (PDA) nanoparticles coated with polyethylene imine (PEI). This delivery system has the advantages of high homogeneity, good stability, excellent biocompatibility, and low toxicity. In vitro antitumor studies showed that the system effectively inhibited the proliferation of mouse breast carcinoma cells and induced cell apoptosis. From the in vivo studies, we found that the system inhibited the growth of mouse breast carcinoma, facilitated the maturation of antigen-presenting cells, promoted T lymphocyte differentiation, and induced the body's immune response. The present study developed a dual functional drug delivery system combining photothermal therapy and immunotherapy to efficiently improve antitumor therapy with potential clinical application.

Combined IL-2, agonistic CD3 and 4-1BB stimulation preserve clonotype hierarchy in propagated non-small cell lung cancer tumor-infiltrating lymphocytes

Background

Adoptive cell transfer (ACT) of tumor-infiltrating lymphocytes (TIL) yielded clinical benefit in patients with checkpoint blockade immunotherapy-refractory non-small cell lung cancer (NSCLC) prompting a renewed interest in TIL-ACT. This preclinical study explores the feasibility of producing a NSCLC TIL product with sufficient numbers and enhanced attributes using an improved culture method.

Methods

TIL from resected NSCLC tumors were initially cultured using (1) the traditional method using interleukin (IL)-2 alone in 24-well plates (TIL 1.0) or (2) IL-2 in combination with agonistic antibodies against CD3 and 4-1BB (Urelumab) in a G-Rex flask (TIL 3.0). TIL subsequently underwent a rapid expansion protocol (REP) with anti-CD3. Before and after the REP, expanded TIL were phenotyped and the complementarity-determining region 3 β variable region of the T-cell receptor (TCR) was sequenced to assess the T-cell repertoire.

Results

TIL 3.0 robustly expanded NSCLC TIL while enriching for CD8⁺ TIL in a shorter manufacturing time when compared with the traditional TIL 1.0 method, achieving a higher success rate and producing 5.3-fold more TIL per successful expansion. The higher proliferative capacity and CD8 content of TIL 3.0 was also observed after the REP. Both steps of expansion did not terminally differentiate/exhaust the TIL but a lesser differentiated population was observed after the first step. TIL initially expanded with the 3.0 method exhibited higher breadth of clonotypes than TIL 1.0 corresponding to a higher repertoire homology with the original tumor, including a higher proportion of the top 10 most prevalent clones from the tumor. TIL 3.0 also retained a higher proportion of putative tumor-specific TCR when compared with TIL 1.0. Numerical expansion of TIL in a REP was found to perturb the clonal hierarchy and lessen the proportion of putative tumor-specific TIL from the TIL 3.0 process.

Conclusions

We report the feasibility of robustly expanding a T-cell repertoire recapitulating the clonal hierarchy of the T cells in the NSCLC tumor, including a large number of putative tumor-specific TIL clones, using the TIL 3.0 methodology. If scaled up and employed as a sole expansion platform, the robustness and speed of TIL 3.0 may facilitate the testing of TIL-ACT approaches in NSCLC.

Nobel Prize for immune checkpoint inhibitors, understanding the immunological switching between immunosuppression and autoimmunity

INTRODUCTION

Immune checkpoint inhibitors (ICIs) are a revolutionary form of immunotherapy in cancer. However, the percentage of patients responding to therapy is relatively low, while adverse effects occur in a large number of patients. In addition, the therapeutic mechanisms of ICIs are not yet completely described.

AREAS COVERED

The initial view (articles published in PubMed, Scopus, Web of Science, etc.) was that ICIs increase tumor-specific immunity. Recent data (collected from the same databases) suggest that the ICIs pharmacotherapy actually extends beyond the topic of immune reactivity, including additional immune pathways, such as disrupting immunosuppression and increasing tumor-specific autoimmunity. Unfortunately, there is no clear delimitation between these specific autoimmune reactions that are therapeutically beneficial, and nonspecific autoimmune reactions/toxicity that can be extremely severe side effects.

EXPERT OPINION

Immune checkpoint mechanisms perform a non-selective immune regulation, maintaining a dynamic balance between immunosuppression and autoimmunity. By blocking these mechanisms, ICIs actually perform an immunological reset, decreasing immunosuppression and increasing tumor-specific immunity and predisposition to autoimmunity. The predisposition to autoimmunity induces both side effects and beneficial autoimmunity. Consequently, further studies are necessary to maximize the beneficial tumor-specific autoimmunity, while reducing the counterproductive effect of associated autoimmune toxicity.

Safety evaluation of the mouse TCRα - transduced T cell product in preclinical models in vivo and in vitro

Adoptive cell therapy (ACT) based on TCR- or CAR-T cells has become an efficient immunotherapeutic approach for the treatment of various diseases, including cancer. Previously, we developed a novel strategy for generating therapeutic T cell products based on chain-centric TCRs, in which either α- or β-chain dominates in cognate antigen recognition. To assess the suitability of our experimental approach for the clinical application and predict its possible adverse effects, in studies here, we evaluated the safety of the experimental TCRα-modified T cell product in mouse preclinical models. Our data showed no tumorigenic or mutagenic activity in vitro of TCRα-transduced T cells, indicating no genotoxicity of viral vectors used for the generation of the experimental T cell product. Adoptive transfer of TCRα-engineered T cells in a wide dose range didn`t disturb the host homeostasis and exhibited no acute toxicity or immunotoxicity in vivo. Based on pharmacokinetics and pharmacodynamics analysis here, modified T cells rapidly penetrated and distributed in many viscera after infusion. Histological evaluations revealed no pathological changes in organs caused by T cells accumulation, indicating the absence of non-specific off-target activity or cross-reactivity of the therapeutic TCRα. Studies here provide valuable information on the potential safety of TCRα-T cell based ACT that could be extrapolated to possible effects in a human host.

An Immunocompetent Microphysiological System to Simultaneously Investigate Effects of Anti-Tumor Natural Killer Cells on Tumor and Cardiac Microtissues

Existing first-line cancer therapies often fail to cope with the heterogeneity and complexity of cancers, so that new therapeutic approaches are urgently needed. Among novel alternative therapies, adoptive cell therapy (ACT) has emerged as a promising cancer treatment in recent years. The limited clinical applications of ACT, despite its advantages over standard-of-care therapies, can be attributed to (i) time-consuming and cost-intensive procedures to screen for potent anti-tumor immune cells and the corresponding targets, (ii) difficulties to translate in-vitro and animal-derived in-vivo efficacies to clinical efficacy in humans, and (iii) the lack of systemic methods for the safety assessment of ACT. Suitable experimental models and testing platforms have the potential to accelerate the development of ACT. Immunocompetent microphysiological systems (iMPS) are microfluidic platforms that enable complex interactions of advanced tissue models with different immune cell types, bridging the gap between in-vitro and in-vivo studies. Here, we present a proof-of-concept iMPS that supports a triple culture of three-dimensional (3D) colorectal tumor microtissues, 3D cardiac microtissues, and human-derived natural killer (NK) cells in the same microfluidic network. Different aspects of tumor-NK cell interactions were characterized using this iMPS including: (i) direct interaction and NK cell-mediated tumor killing, (ii) the development of an inflammatory milieu through enrichment of soluble pro-inflammatory chemokines and cytokines, and (iii) secondary effects on healthy cardiac microtissues. We found a specific NK cell-mediated tumor-killing activity and elevated levels of tumor- and NK cell-derived chemokines and cytokines, indicating crosstalk and development of an inflammatory milieu. While viability and morphological integrity of cardiac microtissues remained mostly unaffected, we were able to detect alterations in their beating behavior, which shows the potential of iMPS for both, efficacy and early safety testing of new candidate ACTs.

Cancer immunotherapy: A comprehensive appraisal of its modes of application

Conventional cancer treatments such as chemotherapy and radiation therapy have reached their therapeutic potential, leaving a gap for developing more effective cancer therapeutics. Cancer cells evade the immune system using various mechanisms of immune tolerance, underlying the potential impact of immunotherapy in the treatment of cancer. Immunotherapy includes several approaches such as activating the immune system in a cytokine-dependent manner, manipulating the feedback mechanisms involved in the immune response, enhancing the immune response via lymphocyte expansion and using cancer vaccines to elicit long-lasting, robust responses. These techniques can be used as monotherapies or combination therapies. The present review describes the immune-based mechanisms involved in tumor cell proliferation and maintenance and the rationale underlying various treatment methods. In addition, the present review provides insight into the potential of immunotherapy used alone or in combination with various types of therapeutics.

ACT Up TIL Now: The Evolution of Tumor-Infiltrating Lymphocytes in Adoptive Cell Therapy for the Treatment of Solid Tumors

The past decades of cancer immunotherapy research have provided profound evidence that the immune system is capable of inducing durable tumor regression. Although many commercialized anti-cancer immunotherapies are available to patients, these treatment options only scrape the surface of the potential immune-related treatment possibilities for cancer. Additionally, many individuals are ineligible for established immunotherapies due to their cancer type. The adoptive cell transfer of autologous tumor-infiltrating lymphocytes has been used in humans for over 30 years to treat metastatic melanoma, and continued modifications are making it increasingly more effective against other types of cancer. This comprehensive review outlines this therapy from its infancy through to the present day, bringing to light modifications and optimizations to the traditional workflow, as well as highlighting the influence of new methods and technologies.

Cytokine Release Syndrome By T-cell-Redirecting Therapies: Can We Predict and Modulate Patient Risk?

T-cell-redirecting therapies are promising new therapeutic options in the field of cancer immunotherapy, but the development of these modalities is challenging. A commonly observed adverse event in patients treated with T-cell-redirecting therapies is cytokine release syndrome (CRS). Its clinical manifestation is a burden on patients, and continues to be a big hurdle in the clinical development of this class of therapeutics. We review different T-cell-redirecting therapies, discuss key factors related to cytokine release and potentially leading to CRS, and present clinical mitigation strategies applied for those modalities. We propose to dissect those risk factors into drug-target-disease-related factors and individual patient risk factors. Aiming to optimize the therapeutic intervention of these modalities, we illustrate how the knowledge on drug-target-disease-related factors, such as target expression, binding affinity, and target accessibility, can be leveraged in a model-based framework and highlight with case examples how modeling and simulation is applied to guide drug discovery and development. We draw attention to the current gaps in predicting the individual patient's risk towards a high-grade CRS, which requires further considerations of risk factors related, but not limited to, the patient's demographics, genetics, underlying pathologies, treatment history, and environmental exposures. The drug-target-disease-related factors together with the individual patient's risk factors can be regarded as the patient's propensity for developing CRS in response to therapy. As an outlook, we suggest implementing a risk scoring system combined with mechanistic modeling to enable the prediction of an individual patient's risk of CRS for a given therapeutic intervention.

Peptide-based and small molecule PD-1 and PD-L1 pharmacological modulators in the treatment of cancer

Cancer immunotherapy is an option to enhance physiological defence mechanism to fight cancer, where natural substances (e.g., antigen/antibody) or small synthetic molecule can be utilized to improve and restore the immune system to stop or slacken the development of malignant cells, stop metastasis and/or help the immune response with synthetic monoclonal antibodies (mAbs) and tumour-agnostic therapy to eliminate cancer cells. Interaction between the programmed cell death ligand 1 (PD-L1) and its receptor (programmed cell death protein 1, PD-1), and cytotoxic T-lymphocyte-associated protein 4 (CTLA4) linked signalling pathways have been identified as perilous towards the body's immune mechanism in regulating the progression of cancer. It is known that certain cancers use these pathways to evade the body's defence mechanism. The immune system is capable of responding to cancer by stalling these trails with specific synthetic antibodies or immune checkpoint inhibitors, which can ultimately either stop or slow cancer cell development. Recent findings and data suggested that using such inhibitors invigorated a new approach to cancer treatment. These inhibitors usually activate the immune system to identify and eliminate cancer cells rather than attacking tumour cells directly. PD-1/PD-L1 inhibitors have already been substantiated for their efficacy in over twenty variations of cancer through different clinical trials. Studies on molecular interaction with existing PD-1/PD-L1 inhibitors that are mainly dominated by antibodies are constantly generating new ideas to develop novel inhibitors. This review has summarised information on reported and/or patented small molecules and peptides for their ability to interact with the PD-1/PD-L1 as a potential anticancer strategy.

Ex Vivo High Salt Activated Tumor-Primed CD4+T Lymphocytes Exert a Potent Anti-Cancer Response

Simple Summary

Cell based immunotherapy is rapidly emerging as a promising cancer treatment. Salt (sodium chloride) treatment to immune cell cultures is known to induce inflammatory activation. In our current study, we analyzed the anti-cancer ability of salt treatment on immune cells outside the host followed by reinfusion into the host. Using a pre-clinical breast cancer model, we demonstrated that external salt treatment on T-cell subset of immune cells produced a viable anti-cancer response, which may have future human clinical application.

Abstract

Cell based immunotherapy is rapidly emerging as a promising cancer treatment. A modest increase in salt (sodium chloride) concentration in immune cell cultures is known to induce inflammatory phenotypic differentiation. In our current study, we analyzed the ability of salt treatment to induce ex vivo expansion of tumor-primed CD4 (cluster of differentiation 4)+T cells to an effector phenotype. CD4+T cells were isolated using immunomagnetic beads from draining lymph nodes and spleens from tumor bearing C57Bl/6 mice, 28 days post-injection of Py230 syngeneic breast cancer cells. CD4+T cells from non-tumor bearing mice were isolated from splenocytes of 12-week-old C57Bl/6 mice. These CD4+T cells were expanded ex vivo with five stimulation cycles, and each cycle comprised of treatment with high salt (Δ0.035 M NaCl) or equimolar mannitol controls along with anti-CD3/CD28 monoclonal antibodies for the first 3 days, followed by the addition of interleukin (IL)-2/IL-7 cytokines and heat killed Py230 for 4 days. Ex vivo high salt treatment induced a two-fold higher Th1 (T helper type 1) expansion and four-fold higher Th17 expansion compared to equimolar mannitol treatment. Importantly, the high salt expanded CD4+T cells retained tumor-specificity, as demonstrated by higher in vitro cytotoxicity against Py230 breast cancer cells and reduced in vivo syngeneic tumor growth. Metabolic studies revealed that high salt treatment enhanced the glycolytic reserve and basal mitochondrial oxidation of CD4+T cells, suggesting a role of high salt in enhanced pro-growth anabolic metabolism needed for inflammatory differentiation. Mechanistic studies demonstrated that the high salt induced switch to the effector phenotype was mediated by tonicity-dependent transcription factor, TonEBP/NFAT5. Using a transgenic murine model, we demonstrated that CD4 specific TonEBP/NFAT5 knock out (CD4^cre/creNFAT5^flox/flox) abrogated the induction of the effector phenotype and anti-tumor efficiency of CD4+T cells following high salt treatment. Taken together, our data suggest that high salt-mediated ex vivo expansion of tumor-primed CD4+T cells could induce effective tumor specific anti-cancer responses, which may have a novel cell-based cancer immunotherapeutic application.

Using CRISPR to enhance T cell effector function for therapeutic applications

T cells are critical to fight pathogenic microbes and combat malignantly transformed cells in the fight against cancer. To exert their effector function, T cells produce effector molecules, such as the pro-inflammatory cytokines IFN-γ, TNF-α and IL-2. Tumors possess many inhibitory mechanisms that dampen T cell effector function, limiting the secretion of cytotoxic molecules. As a result, the control and elimination of tumors is impaired. Through recent advances in genomic editing, T cells can now be successfully modified via CRISPR/Cas9 technology. For instance, engaging (post-)transcriptional mechanisms to enhance T cell cytokine production, the retargeting of T cell antigen specificity or rendering T cells refractive to inhibitory receptor signaling can augment T cell effector function. Therefore, CRISPR/Cas9-mediated genome editing might provide novel strategies for cancer immunotherapy. Recently, the first-in-patient clinical trial was successfully performed with CRISPR/Cas9-modified human T cell therapy. In this review, a brief overview of currently available techniques is provided, and recent advances in T cell genomic engineering for the enhancement of T cell effector function for therapeutic purposes are discussed.

The role of small molecules in cell and gene therapy

Cell and gene therapies have achieved impressive results in the treatment of rare genetic diseases using gene corrected stem cells and haematological cancers using chimeric antigen receptor T cells. However, these two fields face significant challenges such as demonstrating long-term efficacy and safety, and achieving cost-effective, scalable manufacturing processes. The use of small molecules is a key approach to overcome these barriers and can benefit cell and gene therapies at multiple stages of their lifecycle. For example, small molecules can be used to optimise viral vector production during manufacturing or used in the clinic to enhance the resistance of T cell therapies to the immunosuppressive tumour microenvironment. Here, we review current uses of small molecules in cell and gene therapy and highlight opportunities for medicinal chemists to further consolidate the success of cell and gene therapies.

Cellular therapy for the treatment of solid tumors

Adoptive cellular therapy (ACT) is a form of cancer immunotherapy in which lymphocytes are removed from patient blood or tumor samples, expanded and/or genetically modified to improve tumor-fighting capabilities, and infused back into the patient. The main forms of ACT include tumor infiltrating lymphocytes (TILs), engineered T cell receptor (TCR) T cells, and chimeric antigen receptor (CAR) T cells. While ACT has had success in hematological malignancies, particularly in B cell lymphomas targeted with CAR T cells, these favorable outcomes have yet to be replicated in solid tumors. Appropriate solid tumor target antigens are difficult to identify for ACT. Trafficking to tumor sites and infiltrating solid tumor burdens remains a problem for ACT cells. Persistence of ACT cells, which is important in creating a durable response, is also a major challenge, partly attributed to the formidable microtumor environment conditions. The costly and time-intensive manufacturing process for ACT is also an obstacle to widespread adoption. In this review, we discuss the challenges of ACT therapy in the treatment of solid tumors and explore the ongoing efforts to improve this immunotherapy approach in non-hematological malignancies.

Phase I/II study protocol to assess safety and efficacy of adoptive cell therapy with anti-PD-1 plus low-dose pegylated-interferon-alpha in patients with metastatic melanoma refractory to standard of care treatments: the ACTME trial

INTRODUCTION

Treatment with anti-PD-1 immunotherapy does not lead to long-lasting clinical responses in approximately 60% of patients with metastatic melanoma. These refractory patients, however, can still respond to treatment with tumour infiltrating lymphocytes (TIL) and interferon-alpha (IFNa). A combination of TIL, pegylated-interferon-alpha (PEG-IFNa) and anti-PD-1 is expected to provide a safe, feasible and effective therapy for patients with metastatic melanoma, who are refractory to standard of care treatment options.

METHODS AND ANALYSIS

Patients are treated in two phases. In phase I, the safety of the combination TIL and anti-PD-1 is assessed (cohort 1) according to CTCAE 4.03 criteria. Subsequently, the safety of cotreatment with PEG-IFNa is tested in cohort 2. The efficacy will be evaluated in the second phase of the trial. Efficacy is evaluated according to RECIST 1.1 and immune-related response criteria. Clinical and immunological parameters will be evaluated for their relation with clinical responsiveness.

ETHICS AND DISSEMINATION

Ethical approval of the trial was obtained from the Central Committee on Research Involving Human Subjects in the Netherlands. The trial results will be shared with the scientific community at (inter)national conferences and by publication in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT03638375; Pre-results.

Immune Therapy for Central Nervous System Metastasis

Brain metastases lead to substantial morbidity and mortality among patients with advanced malignancies. Although treatment options have traditionally included largely palliative measures, studies of brain metastasis response to immunotherapy are promising. Immune checkpoint inhibitors have shown efficacy in studies of patients with melanoma, renal cell carcinoma, and lung cancer brain metastases. Patients with brain metastases are more frequently included in clinical trials, ushering in a new era in immunotherapy and management for patients with brain metastases. Gaining an understanding of the molecular determination for response to immunotherapies remains a major challenge and is an active area of future research.

Tackling Resistance to Cancer Immunotherapy: What Do We Know?

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

Cellular immunotherapy: a clinical state-of-the-art of a new paradigm for cancer treatment

Cancer immunotherapy has opened a new chapter in Medical Oncology. Many novel therapies are under clinical testing and some have already been approved and implemented in cancer treatment protocols. In particular, cellular immunotherapies take advantage of the antitumor capabilities of the immune system. From dendritic cell-based vaccines to treatments centered on genetically engineered T cells, this form of personalized cancer therapy has taken the field by storm. They commonly share the ex vivo genetic modification of the patient's immune cells to generate or induce tumor antigen-specific immune responses. The latest clinical trials and translational research have shed light on its clinical effectiveness as well as on the mechanisms behind targeting specific antigens or unique tumor alterations. This review gives an overview of the clinical developments in immune cell-based technologies predominantly for solid tumors and on how the latest discoveries are being incorporated within the standard of care.

New emerging targets in cancer immunotherapy: the role of neoantigens

The success of cancer therapies with immune checkpoint inhibitors is transforming the treatment of patients with cancer and fostering cancer research. Therapies that target immune checkpoint inhibitors have shown unprecedented rates of durable long-lasting responses in patients with various cancer types, but only in a fraction of patients. Thus, novel approaches are needed to make immunotherapy more precise and also less toxic. The advances of next-generation sequencing technologies have allowed fast detection of somatic mutations in genes present in the exome of an individual tumour. Targeting neoantigens, the mutated peptides expressed only by tumour cells, may enable antitumour T-cell responses and tumour destruction without causing harm to healthy tissues. Currently, neoantigens can be identified in tumour clinical samples by using genomic-based computational tools. The two main treatment modalities targeting neoantigens that have been investigated in clinical trials are personalised vaccines and tumour infiltrating lymphocytes-based adoptive T-cell therapy. In this mini review, we discuss the promises and challenges for using neoantigens as emergent targets to personalise and guide cancer immunotherapy in a broader set of cancers.

Photothermally activatable PDA immune nanomedicine combined with PD-L1 checkpoint blockade for antimetastatic cancer photoimmunotherapy

Photothermal therapy (PTT) has shown promising potential and bright prospects in damaging primary tumors; however, it is limited to metastatic and recrudescent tumors as PTT requires straightforward light irradiation. Moreover, metastatic and recrudescent tumor immunosuppression due to host T-cell antitumor activity is dramatically impeded because of programmed cell death 1 ligand (PD-L1) and programmed cell death receptor 1 (PD-1) pathways and immune checkpoint blockade (ICB) therapy. In this work, we demonstrate that PTT combined with ICB could not only eliminate primary tumors, but also prevent tumor metastasis to the lungs/liver. In particular, we have designed immunoadjuvant nanomedicine carriers on the basis of polydopamine (PDA) simultaneously loaded with resiquimod (R848)-a kind of toll-like receptor 7 (TLR7) agonist-and carbon dots (CDs)-a fluorescent agent. This nanomedicine is defined as PDA-PEG-R848-CD nanoparticle (NP). The multitasking PDA-PEG-R848-CD NPs can destroy 4T1 breast tumors by PTT under near-infrared laser irradiation in addition to generating tumor-associated antigens. Moreover, the PTT effect triggered the release of R848, thereby inducing a strong antitumor immune response. Meanwhile, this synergistic therapy also shows the abscopal effects by completely inhibiting the growth of untreated distant tumors by effectively triggering the tumors infiltrated by CD3/CD8. Such findings suggest that PDA-PEG-R848-CD NPs could significantly potentiate the systemic therapeutic efficiency of PD-L1 checkpoint blockade therapy by activating both innate and adaptive immune systems in the body.

The Emerging World of TCR-T Cell Trials Against Cancer: A Systematic Review

T-cell receptor-engineered T-cell therapy and chimeric antigen receptor T-cell therapy are 2 types of adoptive T-cell therapy that genetically modify natural T cells to treat cancers. Although chimeric antigen receptor T-cell therapy has yielded remarkable efficacy for hematological malignancies of the B-cell lineages, most solid tumors fail to respond significantly to chimeric antigen receptor T cells. T-cell receptor-engineered T-cell therapy, on the other hand, has shown unprecedented promise in treating solid tumors and has attracted growing interest. In order to create an unbiased, comprehensive, and scientific report for this fast-moving field, we carefully analyzed all 84 clinical trials using T-cell receptor-engineered T-cell therapy and downloaded from ClinicalTrials.gov updated by June 11, 2018. Informative features and trends were observed in these clinical trials. The number of trials initiated each year is increasing as expected, but an interesting pattern is observed. NY-ESO-1, as the most targeted antigen type, is the target of 31 clinical trials; melanoma is the most targeted cancer type and is the target of 33 clinical trials. Novel antigens and underrepresented cancers remain to be targeted in future studies and clinical trials. Unlike chimeric antigen receptor T-cell therapy, only about 16% of the 84 clinical trials target against hematological malignancies, consistent with T-cell receptor-engineered T-cell therapy's high potential for solid tumors. Six pharma/biotech companies with novel T-cell receptor-engineered T-cell ideas and products were examined in this review. Multiple approaches have been utilized in these companies to increase the T-cell receptor's affinity and efficiency and to minimize cross-reactivity. The major challenges in the development of the T-cell receptor-engineered T-cell therapy due to tumor microenvironment were also discussed here.

Adoptive transfer of tumor-infiltrating lymphocytes in melanoma: a viable treatment option

The treatment of metastatic melanoma patients with autologous tumor-infiltrating lymphocytes (TIL) shows robust, reproducible, clinical responses in clinical trials executed in several specialized centers over the world. Even in the era of targeted therapy and immune checkpoint inhibition, TIL therapy can be an additional and clinically relevant treatment line. This review provides an overview of the clinical experiences with TIL therapy thus far, including lymphodepleting regimens, the use of interleukin-2 (IL-2) and the associated toxicity. Characteristics of the TIL products and the antigen recognition pattern will be discussed, as well as the current and upcoming production strategies, including the selective expansion of specific fractions from the cell product. In addition, the future potential of TIL therapy in melanoma and other tumor types will be covered.

Effective antitumor peptide vaccines can induce severe autoimmune pathology

Immunotherapy has shown a tremendous success in treating cancer. Unfortunately, this success is frequently associated with severe autoimmune pathology. In this study, we used the transgenic RIP-gp mouse model to assess the antitumor therapeutic benefit of peptide vaccination while evaluating the possible associated autoimmune pathology. We report that palmitoylated gp33-41 peptide and poly-IC adjuvant vaccine (BiVax) generated ∼ 5-10 % of antigen specific T cell responses in wild type and supposedly immune tolerant RIP-gp mice. Boosting with BiVax in combination with αCD40 antibody (TriVax) or BiVax in combination with IL-2/αIL-2 antibody complexes (IL2Cx) significantly increased the immune responses (∼30-50%). Interestingly, although both boosts were equally effective in generating vast T cell responses, BiVax/IL2Cx showed better control of tumor growth than TriVax. However, this effect was associated with high incidence of diabetes in an antigen and CD8 dependent fashion. T cell responses generated by BiVax/IL2Cx, but not those generated by TriVax were highly resistant to PD-1/PD-L1 inhibitory signals. Nevertheless, PD-1 blockade enhanced the ability of TriVax to control tumor growth but increased the incidence of diabetes. Finally, we show that severe autoimmunity by BiVax/IL2Cx was prevented while preserving outstanding antitumor responses by utilizing a tumor antigen not expressed in the pancreas. Our data provides a clear evidence that peptide based vaccines can expand vast endogenous T cell responses which effectively control tumor growth but with high potential of autoimmune pathology.

Delivering safer immunotherapies for cancer

Cancer immunotherapy is now a powerful clinical reality, with a steady progression of new drug approvals and a massive pipeline of additional treatments in clinical and preclinical development. However, modulation of the immune system can be a double-edged sword: Drugs that activate immune effectors are prone to serious non-specific systemic inflammation and autoimmune side effects. Drug delivery technologies have an important role to play in harnessing the power of immune therapeutics while avoiding on-target/off-tumor toxicities. Here we review mechanisms of toxicity for clinically-relevant immunotherapeutics, and discuss approaches based in drug delivery technology to enhance the safety and potency of these treatments. These include strategies to merge drug delivery with adoptive cellular therapies, targeting immunotherapies to tumors or select immune cells, and localizing therapeutics intratumorally. Rational design employing lessons learned from the drug delivery and nanomedicine fields has the potential to facilitate immunotherapy reaching its full potential.