T-Cell Therapy Using Interleukin-21-Primed Cytotoxic T-Cell Lymphocytes Combined With Cytotoxic T-Cell Lymphocyte Antigen-4 Blockade Results in Long-Term Cell Persistence and Durable Tumor Regression

Next-generation cancer vaccines and emerging immunotherapy combinations

Therapeutic cancer vaccines have been a subject of research for several decades as potential new weapons to tackle malignancies. Their goal is to induce a long-lasting and efficient antitumour-directed immune response, capable of mediating tumour regression, preventing tumour progression, and eradicating minimal residual disease, while avoiding major adverse effects. Development of new vaccine technologies and antigen prediction methods has led to significant improvements in cancer vaccine efficacy. However, for their successful clinical application, certain obstacles still need to be overcome, especially tumour-mediated immunosuppression and escape mechanisms. In this review, we introduce therapeutic cancer vaccines and subsequently discuss combination approaches of next-generation cancer vaccines and existing immunotherapies, particularly immune checkpoint inhibitors (ICIs) and adoptive cell transfer/cell-based immunotherapies.

Optimizing interleukin-6 and 8 expression, clarification and purification in plant cell packs and plants for application in advanced therapy medicinal products and cellular agriculture

Healthcare and nutrition are facing a paradigm shift in light of advanced therapy medicinal products (ATMPs) and cellular agriculture options respectively. Both options heavily rely on some sort of animal cell culture, e.g. autologous stem cells. These cultures require various growth factors, such as interleukin-6 and 8 (IL-6/8), in a pure, safe and sustainable form that can be provided in a scalable manner. Plants seem well suited for this task because purification of small proteins can be readily achieved by membrane separation, human/animal pathogens do not replicate in plants and production can be scaled up using in-door farming or agricultural practices. Here, we illustrate this capacity by first optimizing the codon usage of IL-6/8 for translation in Nicotiana spp., as well as testing the effect of untranslated regions and product targeting to different sub-cellular compartments on expression in a high-throughput plant cell pack (PCP) assay. In the chloroplast, IL-6 accumulated up to 6.9±3.8 (SD, n=2) and 14.4±7.4 mg kg-1 (SD, n=5) were observed in case of IL-8. When transferring IL-8 expression into whole plants, accumulation was 12.3±1.5 mg kg-1 (SD, n=3). After extraction and clarification, IL-8 was purified using a two-stage process consisting of an ultrafiltration/diafiltration step with 100 kDa and 10 kDa cut off membranes followed by an IMAC polishing step. The purity, yield and recovery were 97.8%, 6.6 mg kg-1 and 38%, respectively. We evaluated the ability of the proposed purification process to remove endotoxins to ensure the compatibility of plant-made growth factors with cell culture.

Immunotherapy combination approaches: mechanisms, biomarkers and clinical observations

The approval of the first immune checkpoint inhibitors provided a paradigm shift for the treatment of malignancies across a broad range of indications. Whereas initially, single-agent immune checkpoint inhibition was used, increasing numbers of patients are now treated with combination immune checkpoint blockade, where non-redundant mechanisms of action of the individual agents generally lead to higher response rates. Furthermore, immune checkpoint therapy has been combined with various other therapeutic modalities, including chemotherapy, radiotherapy and other immunotherapeutics such as vaccines, adoptive cellular therapies, cytokines and others, in an effort to maximize clinical efficacy. Currently, a large number of clinical trials test combination therapies with an immune checkpoint inhibitor as a backbone. However, proceeding without inclusion of broad, if initially exploratory, biomarker investigations may ultimately slow progress, as so far, few combinations have yielded clinical successes based on clinical data alone. Here, we present the rationale for combination therapies and discuss clinical data from clinical trials across the immuno-oncology spectrum. Moreover, we discuss the evolution of biomarker approaches and highlight the potential new directions that comprehensive biomarker studies can yield.

Tumor epitope spreading by a novel multivalent therapeutic cellular vaccine targeting cancer antigens to invariant NKT-triggered dendritic cells in situ

Introduction

Cancer is categorized into two types based on the microenvironment: cold and hot tumors. The former is challenging to stimulate through immunity. The immunogenicity of cancer relies on the quality and quantity of cancer antigens, whether recognized by T cells or not. Successful cancer immunotherapy hinges on the cancer cell type, antigenicity and subsequent immune reactions. The T cell response is particularly crucial for secondary epitope spreading, although the factors affecting these mechanisms remain unknown. Prostate cancer often becomes resistant to standard therapy despite identifying several antigens, placing it among immunologically cold tumors. We aim to leverage prostate cancer antigens to investigate the potential induction of epitope spreading in cold tumors. This study specifically focuses on identifying factors involved in secondary epitope spreading based on artificial adjuvant vector cell (aAVC) therapy, a method established as invariant natural killer T (iNKT) -licensed DC therapy.

Methods

We concentrated on three prostate cancer antigens (prostate-specific membrane antigen (PSMA), prostate-specific antigen (PSA), and prostatic acid phosphatase (PAP)). By introducing allogeneic cells with the antigen and murine CD1d mRNA, followed by α-galactosylceramide (α-GalCer) loading, we generated five types of aAVCs, i.e, monovalent, divalent and trivalent antigen-expressing aAVCs and four types of prostate antigen-expressing cold tumors. We evaluated iNKT activation and antigen-specific CD8+ T cell responses against tumor cells prompted by the aAVCs.

Results

Our study revealed that monovalent aAVCs, expressing a single prostate antigen, primed T cells for primary tumor antigens and also induced T cells targeting additional tumor antigens by triggering a tumor antigen-spreading response. When we investigated the immune response by trivalent aAVC (aAVC-PROS), aAVC-PROS therapy elicited multiple antigen-specific CD8+ T cells simultaneously. These CD8+ T cells exhibited both preventive and therapeutic effects against tumor progression.

Conclusions

The findings from this study highlight the promising role of tumor antigen-expressing aAVCs, in inducing efficient epitope spreading and generating robust immune responses against cancer. Our results also propose that multivalent antigen-expressing aAVCs present a promising therapeutic option and could be a more comprehensive therapy for treating cold tumors like prostate cancer.

Personalized neoantigen-based T cell therapy triggers cytotoxic lymphocytes expressing polyclonal TCR against metastatic ovarian cancer

Neoantigen-reactive cytotoxic T lymphocytes play a vital role in precise cancer cell elimination. In this study, we demonstrate the effectiveness of personalized neoantigen-based T cell therapy in inducing tumor regression in two patients suffering from heavily-burdened metastatic ovarian cancer. Our approach involved the development of a robust pipeline for ex vivo expansion of neoantigen-reactive T lymphocytes. Neoantigen peptides were designed and synthesized based on the somatic mutations of the tumors and their predicted HLA binding affinities. These peptides were then presented to T lymphocytes through co-culture with neoantigen-loaded dendritic cells for ex vivo expansion. Subsequent to cell therapy, both patients exhibited significant reductions in tumor marker levels and experienced substantial tumor regression. One patient achieved repeated cancer regression through infusions of T cell products generated from newly identified neoantigens. Transcriptomic analyses revealed a remarkable increase in neoantigen-reactive cytotoxic lymphocytes in the peripheral blood of the patients following cell therapy. These cytotoxic T lymphocytes expressed polyclonal T cell receptors (TCR) against neoantigens, along with abundant cytotoxic proteins and pro-inflammatory cytokines. The efficacy of neoantigen targeting was significantly associated with the immunogenicity and TCR polyclonality. Notably, the neoantigen-specific TCR clonotypes persisted in the peripheral blood after cell therapy. Our findings indicate that personalized neoantigen-based T cell therapy triggers cytotoxic lymphocytes expressing polyclonal TCR against ovarian cancer, suggesting its promising potential in cancer immunotherapy.

Autologous engineered T cell receptor therapy in advanced cancer

To overcome challenges associated with adoptive cell therapy (ACT), we developed a personalized autologous T-cell therapy program. Patients with advanced cancer with HLA-A *02:01 allele and tumor expression of PRAME, MAGEA1, MAGEA4, MAGEA8, NY-ESO-1, COL6A3 exon 6, MXRA5, and/or MMP1 underwent leukapheresis and T-cell product manufacturing. Patients received lymphodepletion, IMA101 infusion and interleukin 2 for 14 days. Of 214 screened patients, 14 were treated (6, IMA101; 8, IMA101 and atezolizumab). The most common adverse events were cytokine release syndrome (G1, n = 6; G2, n = 4) and cytopenia. At 6 weeks, 12 (85.7%) patients had stable disease. Three patients had prolonged disease stabilization for 12.9, 7.3, and 13.7 months, respectively. The median progression-free survival and overall survival were 3.4 months and 9.4 months, respectively. Target-specific T cells expanded to constitute up to 78.7% of CD8+ cells. In conclusion, IMA101 was feasible and well tolerated, leveraging the potential of multi-targeted ACT that warrants further investigation.

T cell receptor therapeutics: immunological targeting of the intracellular cancer proteome

The T cell receptor (TCR) complex is a naturally occurring antigen sensor that detects, amplifies and coordinates cellular immune responses to epitopes derived from cell surface and intracellular proteins. Thus, TCRs enable the targeting of proteins selectively expressed by cancer cells, including neoantigens, cancer germline antigens and viral oncoproteins. As such, TCRs have provided the basis for an emerging class of oncology therapeutics. Herein, we review the current cancer treatment landscape using TCRs and TCR-like molecules. This includes adoptive cell transfer of T cells expressing endogenous or engineered TCRs, TCR bispecific engagers and antibodies specific for human leukocyte antigen (HLA)-bound peptides (TCR mimics). We discuss the unique complexities associated with the clinical development of these therapeutics, such as HLA restriction, TCR retrieval, potency assessment and the potential for cross-reactivity. In addition, we highlight emerging clinical data that establish the antitumour potential of TCR-based therapies, including tumour-infiltrating lymphocytes, for the treatment of diverse human malignancies. Finally, we explore the future of TCR therapeutics, including emerging genome editing methods to safely enhance potency and strategies to streamline patient identification.

Harnessing T cell exhaustion and trogocytosis to isolate patient-derived tumor-specific TCR

To study and then harness the tumor-specific T cell dynamics after allogeneic hematopoietic stem cell transplant, we typed the frequency, phenotype, and function of lymphocytes directed against tumor-associated antigens (TAAs) in 39 consecutive transplanted patients, for 1 year after transplant. We showed that TAA-specific T cells circulated in 90% of patients but display a limited effector function associated to an exhaustion phenotype, particularly in the subgroup of patients deemed to relapse, where exhausted stem cell memory T cells accumulated. Accordingly, cancer-specific cytolytic functions were relevant only when the TAA-specific T cell receptors (TCRs) were transferred into healthy, genome-edited T cells. We then exploited trogocytosis and ligandome-on-chip technology to unveil the specificities of tumor-specific TCRs retrieved from the exhausted T cell pool. Overall, we showed that harnessing circulating TAA-specific and exhausted T cells allow to isolate TCRs against TAAs and previously not described acute myeloid leukemia antigens, potentially relevant for T cell-based cancer immunotherapy.

The molecular perspective on the melanoma and genome engineering of T-cells in targeting therapy

Melanoma, an aggressive malignant tumor originating from melanocytes in humans, is on the rise globally, with limited non-surgical treatment options available. Recent advances in understanding the molecular and cellular mechanisms underlying immune escape, tumorigenesis, drug resistance, and cancer metastasis have paved the way for innovative therapeutic strategies. Combination therapy targeting multiple pathways simultaneously has been shown to be promising in treating melanoma, eliciting favorable responses in most melanoma patients. CAR T-cells, engineered to overcome the limitations of human leukocyte antigen (HLA)-dependent tumor cell detection associated with T-cell receptors, offer an alternative approach. By genetically modifying apheresis-collected allogeneic or autologous T-cells to express chimeric antigen receptors, CAR T-cells can appreciate antigens on cell surfaces independently of major histocompatibility complex (MHC), providing a significant cancer cell detection advantage. However, identifying the most effective target antigen is the initial step, as it helps mitigate the risk of toxicity due to "on-target, off-tumor" and establishes a targeted therapeutic strategy. Furthermore, evaluating signaling pathways and critical molecules involved in melanoma pathogenesis remains insufficient. This study emphasizes the novel approaches of CAR T-cell immunoediting and presents new insights into the molecular signaling pathways associated with melanoma.

Model-informed drug development of autologous CAR-T cell therapy: Strategies to optimize CAR-T cell exposure leveraging cell kinetic/dynamic modeling

Autologous Chimeric antigen receptor (CAR-T) cell therapy has been highly successful in the treatment of aggressive hematological malignancies and is also being evaluated for the treatment of solid tumors as well as other therapeutic areas. A challenge, however, is that up to 60% of patients do not sustain a long-term response. Low CAR-T cell exposure has been suggested as an underlying factor for a poor prognosis. CAR-T cell therapy is a novel therapeutic modality with unique kinetic and dynamic properties. Importantly, "clear" dose-exposure relationships do not seem to exist for any of the currently approved CAR-T cell products. In other words, dose increases have not led to a commensurate increase in the measurable in vivo frequency of transferred CAR-T cells. Therefore, alternative approaches beyond dose titration are needed to optimize CAR-T cell exposure. In this paper, we provide examples of actionable variables - design elements in CAR-T cell discovery, development, and clinical practice, which can be modified to optimize autologous CAR-T cell exposure. Most of these actionable variables can be assessed throughout the various stages of discovery and development as part of a well-informed research and development program. Model-informed drug development approaches can enable such study and program design choices from discovery through to clinical practice and can be an important contributor to cell therapy effectiveness and efficiency.

Feasibility and Safety of Personalized, Multi-Target, Adoptive Cell Therapy (IMA101): First-in-Human Clinical Trial in Patients with Advanced Metastatic Cancer

IMA101 is an actively personalized, multi-targeted adoptive cell therapy (ACT), whereby autologous T cells are directed against multiple novel defined peptide-HLA (pHLA) cancer targets. HLA-A*02:01-positive patients with relapsed/refractory solid tumors expressing ≥1 of 8 predefined targets underwent leukapheresis. Endogenous T cells specific for up to 4 targets were primed and expanded in vitro. Patients received lymphodepletion (fludarabine, cyclophosphamide), followed by T-cell infusion and low-dose IL2 (Cohort 1). Patients in Cohort 2 received atezolizumab for up to 1 year (NCT02876510). Overall, 214 patients were screened, 15 received lymphodepletion (13 women, 2 men; median age, 44 years), and 14 were treated with T-cell products. IMA101 treatment was feasible and well tolerated. The most common adverse events were cytokine release syndrome (Grade 1, n = 6; Grade 2, n = 4) and expected cytopenias. No patient died during the first 100 days after T-cell therapy. No neurotoxicity was observed. No objective responses were noted. Prolonged disease stabilization was noted in three patients lasting for 13.7, 12.9, and 7.3 months. High frequencies of target-specific T cells (up to 78.7% of CD8+ cells) were detected in the blood of treated patients, persisted for >1 year, and were detectable in posttreatment tumor tissue. Individual T-cell receptors (TCR) contained in T-cell products exhibited broad variation in TCR avidity, with the majority being low avidity. High-avidity TCRs were identified in some patients' products. This study demonstrates the feasibility and tolerability of an actively personalized ACT directed to multiple defined pHLA cancer targets. Results warrant further evaluation of multi-target ACT approaches using potent high-avidity TCRs. See related Spotlight by Uslu and June, p. 865.

CrossDome: an interactive R package to predict cross-reactivity risk using immunopeptidomics databases

T-cell-based immunotherapies hold tremendous potential in the fight against cancer, thanks to their capacity to specifically targeting diseased cells. Nevertheless, this potential has been tempered with safety concerns regarding the possible recognition of unknown off-targets displayed by healthy cells. In a notorious example, engineered T-cells specific to MAGEA3 (EVDPIGHLY) also recognized a TITIN-derived peptide (ESDPIVAQY) expressed by cardiac cells, inducing lethal damage in melanoma patients. Such off-target toxicity has been related to T-cell cross-reactivity induced by molecular mimicry. In this context, there is growing interest in developing the means to avoid off-target toxicity, and to provide safer immunotherapy products. To this end, we present CrossDome, a multi-omics suite to predict the off-target toxicity risk of T-cell-based immunotherapies. Our suite provides two alternative protocols, i) a peptide-centered prediction, or ii) a TCR-centered prediction. As proof-of-principle, we evaluate our approach using 16 well-known cross-reactivity cases involving cancer-associated antigens. With CrossDome, the TITIN-derived peptide was predicted at the 99+ percentile rank among 36,000 scored candidates (p-value < 0.001). In addition, off-targets for all the 16 known cases were predicted within the top ranges of relatedness score on a Monte Carlo simulation with over 5 million putative peptide pairs, allowing us to determine a cut-off p-value for off-target toxicity risk. We also implemented a penalty system based on TCR hotspots, named contact map (CM). This TCR-centered approach improved upon the peptide-centered prediction on the MAGEA3-TITIN screening (e.g., from 27th to 6th, out of 36,000 ranked peptides). Next, we used an extended dataset of experimentally-determined cross-reactive peptides to evaluate alternative CrossDome protocols. The level of enrichment of validated cases among top 50 best-scored peptides was 63% for the peptide-centered protocol, and up to 82% for the TCR-centered protocol. Finally, we performed functional characterization of top ranking candidates, by integrating expression data, HLA binding, and immunogenicity predictions. CrossDome was designed as an R package for easy integration with antigen discovery pipelines, and an interactive web interface for users without coding experience. CrossDome is under active development, and it is available at https://github.com/AntunesLab/crossdome.

Engineered murine IL-21-secreting leukemia cells induce granzyme B+ T cells and CD4+CD44+CD62L- effector memory cells while suppressing regulatory T cells, leading to long-term survival

We have explored the use of an IL-21 cell-based anti-leukemia treatment in a mouse model of acute lymphoblastic leukemia. 70Z/3 leukemia cells, engineered to secrete IL-21 and injected into the peritoneum of syngeneic mice, induced a strong anti-leukemia response resulting in 100% survival. Mice that mounted an IL-21-induced anti-leukemia immune response were immune to the parent cell line (no IL-21) when rechallenged.Above a certain threshold, IL-21 secretion correlated with improved survival compared to mice injected with parent 70Z/3 cells. IL-21 was detected in serum with peak levels on day 7, correlating with the maximum expansion of IL-21-secreting 70Z/3 cells which subsequently were eliminated. Mice injected with IL-21-secreting leukemia cells had elevated numbers of granzyme B⁺ CD4⁺ and CD8⁺ T cells in the peritoneum, compared to mice injected with the parent cell line. Regulatory T cells, which increased greatly in 70Z/3-injected mice, failed to do so in mice injected with IL-21-secreting cells. Upon rechallenge, IL-21-primed mice went through a secondary immune response, primarily requiring CD4⁺ T cells, triggering a significant increase of CD4⁺CD44⁺CD62L^- effector memory T cells. Adoptive transfer of T cells from IL21-primed/rechallenged hosts into naïve mice was successful, indicating that IL-21-primed antigen-experienced T cells convey immunity to naïve mice.Our study shows that delivery of IL-21 in a cell-based anti-leukemia protocol has the potential to induce a potent immune response leading to cancer elimination and long-term immunity-properties which make IL-21 an attractive candidate for cancer immunotherapy. Protecting against tumor antigens as well as improving cancer immunity is justified, as current strategies are limited.

Managing the immune microenvironment of osteosarcoma: the outlook for osteosarcoma treatment

Osteosarcoma, with poor survival after metastasis, is considered the most common primary bone cancer in adolescents. Notwithstanding the efforts of researchers, its five-year survival rate has only shown limited improvement, suggesting that existing therapeutic strategies are insufficient to meet clinical needs. Notably, immunotherapy has shown certain advantages over traditional tumor treatments in inhibiting metastasis. Therefore, managing the immune microenvironment in osteosarcoma can provide novel and valuable insight into the multifaceted mechanisms underlying the heterogeneity and progression of the disease. Additionally, given the advances in nanomedicine, there exist many advanced nanoplatforms for enhanced osteosarcoma immunotherapy with satisfactory physiochemical characteristics. Here, we review the classification, characteristics, and functions of the key components of the immune microenvironment in osteosarcoma. This review also emphasizes the application, progress, and prospects of osteosarcoma immunotherapy and discusses several nanomedicine-based options to enhance the efficiency of osteosarcoma treatment. Furthermore, we examine the disadvantages of standard treatments and present future perspectives for osteosarcoma immunotherapy.

TCR-engineered T cell therapy in solid tumors: State of the art and perspectives

T cell engineering has changed the landscape of cancer immunotherapy. Chimeric antigen receptor T cells have demonstrated a remarkable efficacy in the treatment of B cell malignancies in hematology. However, their clinical impact on solid tumors has been modest so far. T cells expressing an engineered T cell receptor (TCR-T cells) represent a promising therapeutic alternative. The target repertoire is not limited to membrane proteins, and intrinsic features of TCRs such as high antigen sensitivity and near-to-physiological signaling may improve tumor cell detection and killing while improving T cell persistence. In this review, we present the clinical results obtained with TCR-T cells targeting different tumor antigen families. We detail the different methods that have been developed to identify and optimize a TCR candidate. We also discuss the challenges of TCR-T cell therapies, including toxicity assessment and resistance mechanisms. Last, we share some perspectives and highlight future directions in the field.

Cytokine conjugation to enhance T cell therapy

Adoptive T cell transfer (ACT) therapies suffer from a number of limitations (e.g., poor control of solid tumors), and while combining ACT with cytokine therapy can enhance effectiveness, this also results in significant side effects. Here, we describe a nanotechnology approach to improve the efficacy of ACT therapies by metabolically labeling T cells with unnatural sugar nanoparticles, allowing direct conjugation of antitumor cytokines onto the T cell surface during the manufacturing process. This allows local, concentrated activity of otherwise toxic cytokines. This approach increases T cell infiltration into solid tumors, activates the host immune system toward a Type 1 response, encourages antigen spreading, and improves control of aggressive solid tumors and achieves complete blood cancer regression with otherwise noncurative doses of CAR-T cells. Overall, this method provides an effective and easily integrated approach to the current ACT manufacturing process to increase efficacy in various settings.

Prognostic value of prognostic nutritional index score and controlling nutritional status score in patients with glioblastoma: A comprehensive meta-analysis

Introduction

Several nutritional indicators, including the prognostic nutritional index (PNI) score and the controlling nutritional status (CONUT) score, have been shown to predict the prognosis of patients with glioblastoma. The present meta-analysis was performed to further evaluate the prognostic value of PNI and CONUT scores in patients with glioblastoma.

Method

The PubMed, EMBASE and Web of Science databases were comprehensively searched for studies that evaluated the ability of PNI and CONUT scores to predict the prognosis of patients with glioblastoma. Hazard ratios (HR) and 95% confidence intervals (CIs) were calculated by univariate and multivariate analyses.

Result

Ten articles were included in this meta-analysis, involving 1406 patients with glioblastoma. Univariate analyses showed that a high PNI score was predictive of greater overall survival (OS; HR 0.50; 95% CI, 0.43, 0.58; I^{2 =} 0%) and progression free survival (PFS; HR 0.63; 95% CI, 0.50, 0.79; I^{2 =} 0%), whereas a low CONUT score predictive of longer OS (HR 2.39; 95% CI, 1.77, 3.23; I^{2 =} 25%). Multivariate analyses showed that high PNI score (HR 0.64; 95% CI, 0.49, 0.84; I^{2 =} 24%) and low CONUT score (HR 2.79; 95% CI, 2.01, 3.89; I^{2 =} 39%) were independently associated with longer OS, whereas PNI score was not significantly associated with PFS (HR 1.02; 95% CI, 0.65, 1.59; I^{2 =} 0%).

Conclusion

PNI scores and CONUT scores have prognostic value in patients with glioblastoma. Additional large-scale studies, however, are required to confirm these results.

Altered MUC1 epitope-specific CTLs: A potential target for immunotherapy of pancreatic cancer

The efficacy of conventional treatments for pancreatic cancer remains unsatisfactory, and immunotherapy is an emerging option for adjuvant treatment of this highly deadly disorder. The tumor-associated antigen (TAA) MUC1 is expressed in a variety of human cancers and is overexpressed in more than 90% of pancreatic cancer, which makes it an attractive target for cancer immunotherapy. As a self-protein, MUC1 shows a low immunogenicity because of immune tolerance, and the most effective approach to breaking immune tolerance is alteration of the antigen structure. In this study, the altered MUC1_1068-1076Y1 epitope (YLQRDISEM) by modification of amino acid residues in sequences presented a higher immunogenicity and elicited more CTLs relative to the wild-type (WT) MUC1_1068-1076 epitope (ELQRDISEM). In addition, the altered MUC1_1068-1076Y1 epitope was found to cross-recognize pancreatic cancer cells expressing WT MUC1 peptides in an HLA-A0201-restricted manner and trigger stronger immune responses against pancreatic cancer via the perforin/granzyme apoptosis pathway. As a potential HLA-A0201-restricted CTL epitope, the altered MUC1_1068-1076Y1 epitope is considered as a promising target for immunotherapy of pancreatic cancer. Alteration of epitope residues may be feasible to solve the problem of the low immunogenicity of TAA and break immune tolerance to induce immune responses against human cancers.

Evolution and modulation of antigen-specific T cell responses in melanoma patients

Analyzing antigen-specific T cell responses at scale has been challenging. Here, we analyze three types of T cell receptor (TCR) repertoire data (antigen-specific TCRs, TCR-repertoire, and single-cell RNA + TCRαβ-sequencing data) from 515 patients with primary or metastatic melanoma and compare it to 783 healthy controls. Although melanoma-associated antigen (MAA) -specific TCRs are restricted to individuals, they share sequence similarities that allow us to build classifiers for predicting anti-MAA T cells. The frequency of anti-MAA T cells distinguishes melanoma patients from healthy and predicts metastatic recurrence from primary melanoma. Anti-MAA T cells have stem-like properties and frequent interactions with regulatory T cells and tumor cells via Galectin9-TIM3 and PVR-TIGIT -axes, respectively. In the responding patients, the number of expanded anti-MAA clones are higher after the anti-PD1(+anti-CTLA4) therapy and the exhaustion phenotype is rescued. Our systems immunology approach paves the way for understanding antigen-specific responses in human disorders.

Previous studies have characterized the diversity and dynamics of the T cell receptor (TCR) repertoire in patients with solid cancer. Here, by analyzing TCR repertoire data from multiple datasets, the authors report that melanoma-associated antigen-specific TCRs can be used to separate metastatic melanoma patients from healthy controls and to follow anti-tumor responses in patients treated with immunotherapy.

Stem cell like memory T cells: A new paradigm in cancer immunotherapy

Stem cell like memory T (T_SCM) cells have emerged as the apex of memory T cell differentiation for their properties of self-renewal and replenishing progenies. With potent long-term persistence, proliferative capacity and antitumor activity, T_SCM cells were thought to be the ideal candidate for cancer immunotherapies. Several strategies have been proposed, such as manipulations of cytokines, metabolic factors, signal pathways, and T cell receptor signal intensity, to induce more T_SCM cells in vitro, in the hope that they could reach a clinical order of magnitude to provide more long-lasting and effective anti-tumor effects in vivo. In this review, we summarized the differentiation characteristics of T_SCM cells and strategies to generate more T_SCM cells. We focused on their roles and application in the cancer immunotherapy especially in adoptive cell transfer therapy and cancer therapeutic vaccines, and hopefully provided clues for future understanding and researches.

Nanodrugs Targeting T Cells in Tumor Therapy

In contrast to conventional anti-tumor agents, nano-carriers allow co-delivery of distinct drugs in a cell type-specific manner. So far, many nanodrug-based immunotherapeutic approaches aim to target and kill tumor cells directly or to address antigen presenting cells (APC) like dendritic cells (DC) in order to elicit tumor antigen-specific T cell responses. Regulatory T cells (Treg) constitute a major obstacle in tumor therapy by inducing a pro-tolerogenic state in APC and inhibiting T cell activation and T effector cell activity. This review aims to summarize nanodrug-based strategies that aim to address and reprogram Treg to overcome their immunomodulatory activity and to revert the exhaustive state of T effector cells. Further, we will also discuss nano-carrier-based approaches to introduce tumor antigen-specific chimeric antigen receptors (CAR) into T cells for CAR-T cell therapy which constitutes a complementary approach to DC-focused vaccination.

The generation and application of antigen-specific T cell therapies for cancer and viral-associated disease

Immunotherapy with antigen-specific T cells is a promising, targeted therapeutic option for patients with cancer as well as for immunocompromised patients with virus infections. In this review, we characterize and compare current manufacturing protocols for the generation of T cells specific to viral and non-viral tumor-associated antigens. Specifically, we discuss: (1) the different methodologies to expand virus-specific T cell and non-viral tumor-associated antigen-specific T cell products, (2) an overview of the immunological principles involved when developing such manufacturing protocols, and (3) proposed standardized methodologies for the generation of polyclonal, polyfunctional antigen-specific T cells irrespective of donor source. Ex vivo expanded cells have been safely administered to treat numerous patients with virus-associated malignancies, hematologic malignancies, and solid tumors. Hence, we have performed a comprehensive review of the clinical trial results evaluating the safety, feasibility, and efficacy of these products in the clinic. In summary, this review seeks to provide new insights regarding antigen-specific T cell technology to benefit a rapidly expanding T cell therapy field.

Cancer Therapy With TCR-Engineered T Cells: Current Strategies, Challenges, and Prospects

To redirect T cells against tumor cells, T cells can be engineered ex vivo to express cancer-antigen specific T cell receptors (TCRs), generating products known as TCR-engineered T cells (TCR T). Unlike chimeric antigen receptors (CARs), TCRs recognize HLA-presented peptides derived from proteins of all cellular compartments. The use of TCR T cells for adoptive cellular therapies (ACT) has gained increased attention, especially as efforts to treat solid cancers with ACTs have intensified. In this review, we describe the differing mechanisms of T cell antigen recognition and signal transduction mediated through CARs and TCRs. We describe the classes of cancer antigens recognized by current TCR T therapies and discuss both classical and emerging pre-clinical strategies for antigen-specific TCR discovery, enhancement, and validation. Finally, we review the current landscape of clinical trials for TCR T therapy and discuss what these current results indicate for the development of future engineered TCR approaches.

A B-cell or a key player? The different roles of B-cells and antibodies in melanoma

The B‐cell system plays an important role in the melanoma immune response; however, consensus has yet to be reached in many facets. Here, we comprehensively review human studies only, due to fundamental differences in the humoral response with animal models. Tumour‐infiltrating B‐cells are associated with contradictory prognostic values, reflecting a lack of agreement between studies on cell subset classification and differences in the markers used, particularly the common use of a single marker not differentiating multiple subsets. Tertiary lymphoid structures (TLS) organise T‐cells and B‐cells within tumours to generate a local anti‐tumour response and TLS presence associates with improved survival in response to immune checkpoint blockade, in late‐stage disease. Autoantibody production is increased in melanoma patients and has been proposed as biomarkers for diagnosis, prognosis and treatment/toxicity response; however, no consistent targets are yet identified. The function of antibodies in an anti‐tumour response is determined by its isotype and subclass; IgG₄ is immune‐suppressive and robustly correlate with poor patient survival in melanoma. We conclude that the current B‐cell literature needs careful interpretation based on the methods used and that we need a consensus of markers to define B‐cells and associated lymphoid organs. Furthermore, future studies need to not only examine antibody targets, but also isotypes when considering functional roles.

Pinpointing the tumor-specific T-cells via TCR clusters

Adoptive cell transfer (ACT) is a promising approach to cancer immunotherapy, but its efficiency fundamentally depends on the extent of tumor-specific T cell enrichment within the graft. This can be estimated via activation with identifiable neoantigens, tumor-associated antigens (TAAs), or living or lysed tumor cells, but these approaches remain laborious, time-consuming, and functionally limited, hampering clinical development of ACT. Here, we demonstrate that homology cluster analysis of T cell receptor (TCR) repertoires efficiently identifies tumor-reactive TCRs allowing to: (1) detect their presence within the pool of tumor-infiltrating lymphocytes (TILs); (2) optimize TIL culturing conditions, with IL-2_low/IL-21/anti-PD-1 combination showing increased efficiency; (3) investigate surface marker-based enrichment for tumor-targeting T cells in freshly isolated TILs (enrichment confirmed for CD4⁺ and CD8⁺ PD-1⁺/CD39⁺ subsets), or re-stimulated TILs (informs on enrichment in 4-1BB-sorted cells). We believe that this approach to the rapid assessment of tumor-specific TCR enrichment should accelerate T cell therapy development.

Correlation Between TCF7+ T Cells and Prognosis of Patients With Oral Squamous Cell Carcinoma

Objective

To investigate whether TCF7⁺ T cells constitute an important factor to improve the existing postoperative prediction model for patients with oral squamous cell carcinoma.

Method

TCF7⁺ T cells were detected in the tissues of 167 OSCC patients by multiplex immunofluorescence. The percentage of TCF7⁺ T cells was transformed into a dichotomous variable, combined with the clinicopathological data for the OSCC patients, and then subjected to univariate and multivariate analyses. The derived independent predictors were then incorporated into risk models to analyze their relationship with the prognosis of patients.

Results

The high TCF7⁺ group had a better prognosis than the low TCF7⁺ group (OS: p<0.001; RFS: p<0.001). Univariate and multivariate analyses showed that TCF7⁺ T cells serve as an independent predictor of OSCC (univariate/multivariate analysis: p<0.001). In Cox risk progression models, inclusion of the TCF7⁺ T cell percentage improved the predictive accuracy of Grade and TNM stage (Grade-OS/RFS: p<0.001; TNM-OS/RFS: p<0.001; TNM+Grade-OS: p<0.001, TNM+Grade-RFS: p=0.004). Inclusion of the TCF7⁺ T cell percentage improved the clinical utility.

Conclusions

TCF7⁺ T cells can act as an independent predictor for postoperative OSCC patients. The inclusion of TCF7⁺ T cells improved the predictive accuracy and clinical utility of the nomograms to different degrees.

New Developments in T Cell Immunometabolism and Implications for Cancer Immunotherapy

Despite rapid advances in the field of immunotherapy, the elimination of established tumors has not been achieved. Many promising new treatments such as adoptive cell therapy (ACT) fall short, primarily due to the loss of T cell effector function or the failure of long-term T cell persistence. With the availability of new tools and advancements in technology, our understanding of metabolic processes has increased enormously in the last decade. Redundancy in metabolic pathways and overlapping targets that could address the plasticity and heterogenous phenotypes of various T cell subsets have illuminated the need for understanding immunometabolism in the context of multiple disease states, including cancer immunology. Herein, we discuss the developing field of T cell immunometabolism and its crucial relevance to improving immunotherapeutic approaches. This in-depth review details the metabolic pathways and preferences of the antitumor immune system and the state of various metabolism-targeting therapeutic approaches.

The Prognostic Value of the Prognostic Nutritional Index in Operable High-Grade Glioma Patients and the Establishment of a Nomogram

Background

Studies confirmed the predictive value of the prognostic nutrition index (PNI) in many malignant tumors. However, it did not reach a consensus in glioma. Therefore, this study investigated the prognostic value of preoperative PNI in operable high-grade glioma and established a nomogram.

Methods

Clinical data of high-grade glioma patients were retrospectively analyzed. The primary endpoint was overall survival (OS). Survival analysis was conducted by the Kaplan–Meier method, log-rank test, and Cox regression analysis. A nomogram was established. The prediction effect of the nomogram covering PNI was verified by area under the curve (AUC).

Results

A total of 91 operable high-grade glioma patients were included. Kaplan–Meier analysis showed that among grade IV gliomas (n = 55), patients with higher PNI (>44) showed a trend of OS benefit (p = 0.138). In grade III glioma (n = 36), patients with higher PNI (>47) had longer OS (p = 0.023). However, the intersecting Kaplan–Meier curve suggested that there may be some confounding factors. Cox regression analysis showed that higher PNI was an independent prognostic factor for grade IV glioma (HR = 0.388, p = 0.040). In grade III glioma, there was no statistically relationship between PNI levels and prognosis. When evaluating the prognostic ability of PNI alone by ROC, the AUC in grade III and IV gliomas was low, indicating that PNI alone had poor predictive power for OS. Interestingly, we found that the nomogram including preoperative PNI, age, extent of resection, number of gliomas, and MGMT methylation status could predict the prognosis of patients with grade IV glioma well.

Conclusion

The PNI level before surgery was an independent prognostic factor for patients with grade IV glioma. The nomogram covering PNI in patients with grade IV glioma also proved the value of PNI. However, the value of PNI in grade III glioma needs to be further evaluated. More prospective studies are needed to verify this conclusion.

Diverse and precision therapies open new horizons for patients with advanced pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a common cause of cancer-related death, and most patients are with advanced disease when diagnosed. At present, despite a variety of treatments have been developed for PDAC, few effective treatment options are available; on the other hand, PDAC shows significant resistance to chemoradiotherapy, targeted therapy, and immunotherapy due to its heterogeneous genetic profile, molecular signaling pathways, and complex tumor immune microenvironment. Nevertheless, over the past decades, there have been many new advances in the key theory and understanding of the intrinsic mechanisms and complexity of molecular biology and molecular immunology in pancreatic cancer, based on which more and more diverse new means and reasonable combination strategies for PDAC treatment have been developed and preliminary breakthroughs have been made. With the continuous exploration, from surgical local treatment to comprehensive medical management, the research-diagnosis-management system of pancreatic cancer is improving. This review focused on the variety of treatments for advanced PDAC, including traditional chemotherapy, targeted therapy, immunotherapy, microenvironment matrix regulation as well as the treatment targeting epigenetics, metabolism and cancer stem cells. We pointed out the current research bottlenecks and future exploration directions.

The importance of immune checkpoints in immune monitoring: A future paradigm shift in the treatment of cancer

The growth and development of cancer are directly correlated to the suppression of the immune system. A major breakthrough in cancer immunotherapy depends on various mechanisms to detect immunosuppressive factors that inhibit anti-tumor immune responses. Immune checkpoints are expressed on many immune cells such as T-cells, regulatory B cells (Bregs), dendritic cells (DCs), natural killer cells (NKs), regulatory T (Tregs), M2-type macrophages, and myeloid-derived suppressor cells (MDSCs). Immune inhibitory molecules, including CTLA-4, TIM-3, TIGIT, PD-1, and LAG-3, normally inhibit immune responses via negatively regulating immune cell signaling pathways to prevent immune injury. However, the up-regulation of inhibitory immune checkpoints during tumor progression on immune cells suppresses anti-tumor immune responses and promotes immune escape in cancer. It has recently been indicated that cancer cells can up-regulate various pathways of the immune checkpoints. Therefore, targeting immune inhibitory molecules through antibodies or miRNAs is a promising therapeutic strategy and shows favorable results. Immune checkpoint inhibitors (ICIs) are introduced as a new immunotherapy strategy that enhance immune cell-induced antitumor responses in many patients. In this review, we highlighted the function of each immune checkpoint on different immune cells and therapeutic strategies aimed at using monoclonal antibodies and miRNAs against inhibitory receptors. We also discussed current challenges and future strategies for maximizing these FDA-approved immunosuppressants' effectiveness and clinical success in cancer treatment.

Cancer immunotherapy: Challenges and limitations

Although cancer immunotherapy has taken center stage in mainstream oncology inducing complete and long-lasting tumor regression, only a subset of patients receiving treatment respond and others relapse after an initial response. Different tumor types respond differently, and even in cancer types that respond (hot tumors), we still observe tumors that are unresponsive (cold tumors), suggesting the presence of resistance. Hence, the development of intrinsic or acquired resistance is a big challenge for the cancer immunotherapy field. Resistance to immunotherapy, including checkpoint inhibitors, CAR-T cell therapy, oncolytic viruses, and recombinant cytokines arises due to cancer cells employing several mechanisms to evade immunosurveillance.

Epitope spreading driven by the joint action of CART cells and pharmacological STING stimulation counteracts tumor escape via antigen-loss variants

Background

Target antigen (Ag) loss has emerged as a major cause of relapse after chimeric antigen receptor T (CART)-cell therapy. We reasoned that the combination of CART cells, with the consequent tumor debulking and release of Ags, together with an immunomodulatory agent, such as the stimulator of interferon gene ligand (STING-L) 2′3′-cyclic GMP-AMP (2′3′-cGAMP), may facilitate the activation of an endogenous response to secondary tumor Ags able to counteract this tumor escape mechanism.

Methods

Mice bearing B16-derived tumors expressing prostate-specific membrane Ag or gp75 were treated systemically with cognate CART cells followed by intratumoral injections of 2′3′-cGAMP. We studied the target Ag inmunoediting by CART cells and the effect of the CART/STING-L combination on the control of STING-L-treated and STING-L-non-treated tumors and on the endogenous antitumor T-cell response. The role of Batf3-dependent dendritic cells (DCs), stimulator of interferon gene (STING) signaling and perforin (Perf)-mediated killing in the efficacy of the combination were analyzed.

Results

Using an immune-competent solid tumor model, we showed that CART cells led to the emergence of tumor cells that lose the target Ag, recreating the cancer immunoediting effect of CART-cell therapy. In this setting, the CART/STING-L combination, but not the monotherapy with CART cells or STING-L, restrained tumor progression and enhanced overall survival, showing abscopal effects on distal STING-L-non-treated tumors. Interestingly, a secondary immune response against non-chimeric antigen receptor-targeted Ags (epitope spreading), as determined by major histocompatibility complex-I-tetramer staining, was fostered and its intensity correlated with the efficacy of the combination. This was consistent with the oligoclonal expansion of host T cells, as revealed by in-depth T-cell receptor repertoire analysis. Moreover, only in the combination group did the activation of endogenous T cells translate into a systemic antitumor response. Importantly, the epitope spreading and the antitumor effects of the combination were fully dependent on host STING signaling and Batf3-dependent DCs, and were partially dependent on Perf release by CART cells. Interestingly, the efficacy of the CART/STING-L treatment also depended on STING signaling in CART cells.

Conclusions

Our data show that 2′3′-cGAMP is a suitable adjuvant to combine with CART-cell therapy, allowing the induction of an endogenous T-cell response that prevents the outgrowth of Ag-loss tumor variants.

The emergence of tumor-infiltrating lymphocytes in nasopharyngeal carcinoma: Predictive value and immunotherapy implications

The clinical study of nasopharyngeal carcinoma (NPC) often reveals a large number of lymphocytes infiltrating the primary tumor site. As an important part of the tumor microenvironment, tumor-infiltrating lymphocytes (TILs) do not exist alone but as a complex multicellular population with high heterogeneity. TILs play an extremely significant role in the occurrence, development, invasion and metastasis of NPC. The latest research shows that they participate in tumorigenesis and treatment, and the composition, quantity, functional status and distribution of TILs subsets have good predictive value for the prognosis of NPC patients. TILs are an independent prognostic factor for TNM stage and significantly correlated with better prognosis. Additionally, adoptive immunotherapy using anti-tumor TILs has achieved good results in a variety of solid tumors including NPC. This review evaluates recent clinical and preclinical studies of NPC, summarizes the role of TILs in promoting and inhibiting tumor growth, evaluates the predictive value of TILs, and explores the potential benefits of TILs-based immunotherapy in the treatment of NPC.

Immunogenic SARS-CoV2 Epitopes Defined by Mass Spectrometry

SARS-CoV-2 infections elicit both humoral and cellular immune responses. For the prevention and treatment of COVID19, the disease caused by SARS-CoV-2, T cell responses are important in mediating recovery and immune-protection. The identification of immunogenic epitopes that can elicit a meaningful T cell response can be elusive. Traditionally, this has been achieved using sophisticated in silico methods to predict putative epitopes; however, our previous studies find that 'immunodominant' SARS-CoV-2 peptides defined by such in silico methods often fail to elicit T cell responses recognizing SARS-CoV-2. We postulated that immunogenic epitopes for SARS-CoV-2 are best defined by directly analyzing peptides eluted from the peptide-MHC complex and then validating immunogenicity empirically by determining if such peptides can elicit T cells recognizing SARS-CoV-2 antigen-expressing cells. Using a tandem mass spectrometry approach, we identified epitopes of SARS-CoV-2 derived not only from structural but also non-structural genes in regions highly conserved among SARS-CoV-2 strains including recently recognized variants. We report here, for the first time, several novel SARS-CoV-2 epitopes from membrane glycol-protein (MGP) and non-structure protein-13 (NSP13) defined by mass-spectrometric analysis of MHC-eluted peptides, provide empiric evidence for their immunogenicity to induce T cell response.

Significance Statement

Current state of the art uses putative epitope peptides based on in silico prediction algorithms to evaluate the T cell response among COVID-19 patients. However, none of these peptides have been tested for immunogenicity, i.e. the ability to elicit a T cell response capable of recognizing endogenously presented peptide. In this study, we used MHC immune-precipitation, acid elution and tandem mass spectrometry to define the SARS-CoV-2 immunopeptidome for membrane glycol-protein and the non-structural protein. Furthermore, taking advantage of a highly robust endogenous T cell (ETC) workflow, we verify the immunogenicity of these MS-defined peptides by in vitro generation of MGP and NSP13 peptide-specific T cells and confirm T cell recognition of MGP or NSP13 endogenously expressing cell lines.

In Silico Defined SARS-CoV2 Epitopes May Not Predict Immunogenicity to COVID19

SARS-CoV-2 infections elicit both humoral and cellular immune responses. For the prevention and treatment of COVID19, the disease caused by SARS-CoV-2, it has become increasingly apparent that T cell responses are equally, if not more important than humoral responses in mediating recovery and immune-protection. One of the major challenges in developing T cell-based therapies for infectious and malignant diseases has been the identification of immunogenic epitopes that can elicit a meaningful T cell response. Traditionally, this has been achieved using sophisticated in silico methods to predict putative epitopes deduced from binding affinities and consensus data. Our studies find that, in contrast to current dogma, 'immunodominant' SARS-CoV-2 peptides defined by such in silico methods often fail to elicit T cell responses recognizing naturally presented SARS-CoV-2 epitopes.

Chimeric Antigen Receptor (CAR) T Cell Therapy for Metastatic Melanoma: Challenges and Road Ahead

Metastatic melanoma is the most aggressive and difficult to treat type of skin cancer, with a survival rate of less than 10%. Metastatic melanoma has conventionally been considered very difficult to treat; however, recent progress in understanding the cellular and molecular mechanisms involved in the tumorigenesis, metastasis and immune escape have led to the introduction of new therapies. These include targeted molecular therapy and novel immune-based approaches such as immune checkpoint blockade (ICB), tumor-infiltrating lymphocytes (TILs), and genetically engineered T-lymphocytes such as chimeric antigen receptor (CAR) T cells. Among these, CAR T cell therapy has recently made promising strides towards the treatment of advanced hematological and solid cancers. Although CAR T cell therapy might offer new hope for melanoma patients, it is not without its shortcomings, which include off-target toxicity, and the emergence of resistance to therapy (e.g., due to antigen loss), leading to eventual relapse. The present review will not only describe the basic steps of melanoma metastasis, but also discuss how CAR T cells could treat metastatic melanoma. We will outline specific strategies including combination approaches that could be used to overcome some limitations of CAR T cell therapy for metastatic melanoma.

Chimeric Antigen Receptor T Cells for Glioblastoma: Current Concepts, Challenges, and Future Perspectives

Glioblastoma is the most common malignant primary brain tumor and is associated with a poor prognosis even after multimodal therapy. Chimeric antigen receptor (CAR) T cells have emerged as a promising therapeutic avenue in glioblastoma. CARs incorporate antigen-recognition moieties that endow autologous T cells with specificity against antigens expressed on glioblastoma (e.g., interleukin [IL]-13Rα2, epidermal growth factor receptor variant III [EGFRvIII], and human epidermal growth factor receptor 2 [HER2]). Compelling antitumor effects of such therapy have been shown in murine glioblastoma models. In humans, 5 phase I/II studies on IL-13Rα2-, EGFRvIII-, and HER2-directed CAR T cells for the treatment of glioblastoma have been published suggesting an acceptable safety profile. However, antitumor effects fell short of expectations in these initial clinical studies. Tumor heterogeneity, antigen loss, and the immunosuppressive tumor microenvironment are among the most important factors to limit the efficacy of CAR T-cell therapy in glioblastoma. Novel target antigens, modification of CAR T-cell design, the combination of CAR T-cell therapy with other therapeutic approaches, but also the use of CAR natural killer cells or CAR macrophages may optimize antitumor effects. Numerous clinical trials studying such approaches are ongoing, as well as several preclinical studies. With an increasing understanding of immune-escape mechanisms of glioblastoma and novel manufacturing techniques for CARs, CAR T cells may provide clinically relevant activity in glioblastoma. This review focuses on the use of CAR T cells in glioblastoma, but also introduces the basic structure, mechanisms of action, and relevant side effects of CAR T cells.

Cell therapies in ovarian cancer

Epithelial ovarian cancer (EOC) is the most important cause of gynecological cancer-related mortality. Despite improvements in medical therapies, particularly with the incorporation of drugs targeting homologous recombination deficiency, EOC survival rates remain low. Adoptive cell therapy (ACT) is a personalized form of immunotherapy in which autologous lymphocytes are expanded, manipulated ex vivo, and re-infused into patients to mediate cancer rejection. This highly promising novel approach with curative potential encompasses multiple strategies, including the adoptive transfer of tumor-infiltrating lymphocytes, natural killer cells, or engineered immune components such as chimeric antigen receptor (CAR) constructs and engineered T-cell receptors. Technical advances in genomics and immuno-engineering have made possible neoantigen-based ACT strategies, as well as CAR-T cells with increased cell persistence and intratumoral trafficking, which have the potential to broaden the opportunity for patients with EOC. Furthermore, dendritic cell-based immunotherapies have been tested in patients with EOC with modest but encouraging results, while the combination of DC-based vaccination as a priming modality for other cancer therapies has shown encouraging results. In this manuscript, we provide a clinically oriented historical overview of various forms of cell therapies for the treatment of EOC, with an emphasis on T-cell therapy.

Adoptive T Cell Therapy for Solid Tumors: Pathway to Personalized Standard of Care

Adoptive cell therapy (ACT) with tumor-infiltrating T cells (TILs) has emerged as a promising therapy for the treatment of unresectable or metastatic solid tumors. One challenge to finding a universal anticancer treatment is the heterogeneity present between different tumors as a result of genetic instability associated with tumorigenesis. As the epitome of personalized medicine, TIL-ACT bypasses the issue of intertumoral heterogeneity by utilizing the patient’s existing antitumor immune response. Despite being one of the few therapies capable of inducing durable, complete tumor regression, many patients fail to respond. Recent research has focused on increasing therapeutic efficacy by refining various aspects of the TIL protocol, which includes the isolation, ex vivo expansion, and subsequent infusion of tumor specific lymphocytes. This review will explore how the therapy has evolved with time by highlighting various resistance mechanisms to TIL therapy and the novel strategies to overcome them.

Histiocyte predominant myocarditis resulting from the addition of interferon gamma to cyclophosphamide-based lymphodepletion for adoptive cellular therapy

Background

Adoptive cellular therapy (ACT) is a promising treatment for synovial sarcoma (SS) with reported response rates of over 50%. However, more work is needed to obtain deeper and more durable responses. SS has a ‘cold’ tumor immune microenvironment with low levels of major histocompatibility complex (MHC) expression and few T-cell infiltrates, which could represent a barrier toward successful treatment with ACT. We previously demonstrated that both MHC expression and T-cell infiltration can be increased using systemic interferon gamma (IFN-γ), which could improve the efficacy of ACT for SS.

Case presentation

We launched a phase I trial incorporating four weekly doses of IFN-γ in an ACT regimen of high-dose cyclophosphamide (HD Cy), NY-ESO-1-specific T cells, and postinfusion low-dose interleukin (IL)-2. Two patients were treated. While one patient had significant tumor regression and resultant clinical benefit, the other patient suffered a fatal histiocytic myocarditis. Therefore, this cohort was terminated for safety concerns.

Conclusion

We describe a new and serious toxicity of immunotherapy from IFN-γ combined with HD Cy-based lymphodepletion and low-dose IL-2. While IFN-γ should not be used concurrently with HD Cy or with low dose IL-2, IFN-γ may still be important in sensitizing SS for ACT. Future studies should avoid using IFN-γ during the immediate period before/after cell infusion.

Trial registration numbers

NCT04177021, NCT01957709, and NCT03063632.

Development of a CD8 co-receptor independent T-cell receptor specific for tumor-associated antigen MAGE-A4 for next generation T-cell-based immunotherapy

BACKGROUND

The cancer-testis antigen MAGE-A4 is an attractive target for T-cell-based immunotherapy, especially for indications with unmet clinical need like non-small cell lung or triple-negative breast cancer.

METHODS

An unbiased CD137-based sorting approach was first used to identify an immunogenic MAGE-A4-derived epitope (GVYDGREHTV) that was properly processed and presented on human leukocyte antigen (HLA)-A2 molecules encoded by the HLA-A*02:01 allele. To isolate high-avidity T cells via subsequent multimer sorting, an in vitro priming approach using HLA-A2-negative donors was conducted to bypass central tolerance to this self-antigen. Pre-clinical parameters of safety and activity were assessed in a comprehensive set of in vitro and in vivo studies.

RESULTS

A MAGE-A4-reactive, HLA-A2-restricted T-cell receptor (TCR) was isolated from primed T cells of an HLA-A2-negative donor. The respective TCR-T-cell (TCR-T) product bbT485 was demonstrated pre-clinically to have a favorable safety profile and superior in vivo potency compared with TCR-Ts expressing a TCR derived from a tolerized T-cell repertoire to self-antigens. This natural high-avidity TCR was found to be CD8 co-receptor independent, allowing effector functions to be elicited in transgenic CD4+ T helper cells. These CD4+ TCR-Ts supported an anti-tumor response by direct killing of MAGE-A4-positive tumor cells and upregulated hallmarks associated with helper function, such as CD154 expression and release of key cytokines on tumor-specific stimulation.

CONCLUSION

The extensive pre-clinical assessment of safety and in vivo potency of bbT485 provide the basis for its use in TCR-T immunotherapy studies. The ability of this non-mutated high-avidity, co-receptor-independent TCR to activate CD8+ and CD4+ T cells could potentially provide enhanced cellular responses in the clinical setting through the induction of functionally diverse T-cell subsets that goes beyond what is currently tested in the clinic.

Considerations when treating high-grade pediatric glioma patients with immunotherapy

INTRODUCTION

Children with high-grade gliomas (pHGGs) represent a clinical population in substantial need of new therapeutic options given the inefficacy and toxicity of current standard-of-care modalities. Although immunotherapy has emerged as a promising modality, it has yet to elicit a significant survival benefit for pHGG patients. While preclinical studies address a variety of underlying challenges, translational clinical trial design and management also need to reflect the most updated progress and lessons from the field.

AREAS COVERED

The authors will focus our discussion on the design of clinical trials, the management of potential toxicities, immune monitoring, and novel biomarkers. Clinical trial design should integrate appropriate patient populations, novel, and preclinically optimized trial design, and logical treatment combinations, particularly those which synergize with standard of care modalities. However, there are caveats due to the nature of immunotherapy trials, such as patient selection bias, evidenced by the frequent exclusion of patients on high-dose corticosteroids. Robust immune-modulating effects of modern immunotherapy can have toxicities. As such, it is important to understand and manage these, especially in pHGG patients.

EXPERT OPINION

Adequate integration of these considerations should allow us to effectively gain insights on biological activity, safety, and biomarkers associated with benefits for patients.

Immunotherapy for osteosarcoma: Fundamental mechanism, rationale, and recent breakthroughs

Osteosarcoma (OS) is the most common primary malignancy of the bone and has a high propensity for local invasion and metastasis. Although combining surgery with chemotherapy has immensely improved the outcomes of osteosarcoma patients, the prognosis of metastatic or recurrent osteosarcomas is still unsatisfactory. Immunotherapy has proven to be a promising therapeutic strategy against human malignancies and improved understanding of the immune response to OS, and biomarker development has increased the number of patients who benefit from immunotherapies in recent years. Here, we review recent advances in immunotherapy in osteosarcoma and discuss the mechanisms and status of immunotherapies in both preclinical and clinical trials as well as future therapies on the horizon. These advances may pave the way for novel treatments requisite for patients with osteosarcoma in need of new therapies.

Non-invasive monitoring of the kinetic infiltration and therapeutic efficacy of nanoparticle-labeled chimeric antigen receptor T cells in glioblastoma via 7.0-Tesla magnetic resonance imaging

BACKGROUND AIMS

Chimeric antigen receptor (CAR) T-cell therapy is a promising treatment strategy in solid tumors. In vivo cell tracking techniques can help us better understand the infiltration, persistence and therapeutic efficacy of CAR T cells. In this field, magnetic resonance imaging (MRI) can achieve high-resolution images of cells by using cellular imaging probes. MRI can also provide various biological information on solid tumors.

METHODS

The authors adopted the amino alcohol derivatives of glucose-coated nanoparticles, ultra-small superparamagnetic particles of iron oxide (USPIOs), to label CAR T cells for non-invasive monitoring of kinetic infiltration and persistence in glioblastoma (GBM). The specific targeting CARs included anti-human epidermal growth factor receptor variant III and IL13 receptor subunit alpha 2 CARs.

RESULTS

When using an appropriate concentration, USPIO labeling exerted no negative effects on the biological characteristics and killing efficiency of CAR T cells. Increasing hypointensity signals could be detected in GBM models by susceptibility-weighted imaging MRI ranging from 3 days to 14 days following the injection of USPIO-labeled CAR T cells. In addition, nanoparticles and CAR T cells were found on consecutive histopathological sections. Moreover, diffusion and perfusion MRI revealed significantly increased water diffusion and decreased vascular permeability on day 3 after treatment, which was simultaneously accompanied by a significant decrease in tumor cell proliferation and increase in intercellular tight junction on immunostaining sections.

CONCLUSION

These results establish an effective imaging technique that can track CAR T cells in GBM models and validate their early therapeutic effects, which may guide the evaluation of CAR T-cell therapies in solid tumors.

Vestigial-like 1 is a shared targetable cancer-placenta antigen expressed by pancreatic and basal-like breast cancers

Cytotoxic T lymphocyte (CTL)-based cancer immunotherapies have shown great promise for inducing clinical regressions by targeting tumor-associated antigens (TAA). To expand the TAA landscape of pancreatic ductal adenocarcinoma (PDAC), we performed tandem mass spectrometry analysis of HLA class I-bound peptides from 35 PDAC patient tumors. This identified a shared HLA-A*0101 restricted peptide derived from co-transcriptional activator Vestigial-like 1 (VGLL1) as a putative TAA demonstrating overexpression in multiple tumor types and low or absent expression in essential normal tissues. Here we show that VGLL1-specific CTLs expanded from the blood of a PDAC patient could recognize and kill in an antigen-specific manner a majority of HLA-A*0101 allogeneic tumor cell lines derived not only from PDAC, but also bladder, ovarian, gastric, lung, and basal-like breast cancers. Gene expression profiling reveals VGLL1 as a member of a unique group of cancer-placenta antigens (CPA) that may constitute immunotherapeutic targets for patients with multiple cancer types.

Identifying and Targeting Human Tumor Antigens for T Cell-Based Immunotherapy of Solid Tumors

Cancer elimination in humans can be achieved with immunotherapy that relies on T lymphocyte-mediated recognition of tumor antigens. Several types of these antigens have been recognized based on their cellular origins and expression patterns, while their detection has been greatly facilitated by recent achievements in next-generation sequencing and immunopeptidomics. Some of them have been targeted in clinical trials with various immunotherapy approaches, while many others remain untested. Here, we discuss molecular identification of different tumor antigen types, and the clinical safety and efficacy of targeting them with immunotherapy. Additionally, we suggest strategies to increase the efficacy and availability of antigen-directed immunotherapies for treatment of patients with metastatic cancer.

Co-expressing LRP6 With Anti-CD19 CAR-T Cells for Improved Therapeutic Effect Against B-ALL

Background

Cellular immunotherapies, such as chimeric antigen receptor modified-T cell (CAR-T) therapy, offers excellent potential for tumor treatment. The memory phenotype of CAR-T has been correlated positively with a therapeutic effect on and prognosis of cancer.

Method

The proliferation rates of novel CAR-T was determined by cell counting. The phenotypes of CAR-T cells were then detected by flow cytometry. The cell cytotoxicity against tumor cells in vitro was investigated by lactate dehydrogenase assay and luciferase assay. The cytokines secreted during these assays were determined by the cytometric bead array assay. The antitumor ability in vivo was evaluated in NOG mice.

Results

Co-expression of an LRP6 full-length protein with anti-CD19 CAR significantly improved the memory phenotype of CAR-positive T-cells by enhancing the wnt signaling pathway. As compared with anti-CD19 CAR-T, anti-CD19 CAR-T-LRP6 exhibited more robust cytotoxicity against tumor cells in vitro and in vivo, albeit fewer cytokines were released in vitro. Moreover, the longer survival rate and robust expansion in vivo of anti-CD19 CAR-T-LRP6 cells were found to be effective in inhibiting cancer recurrence.

Conclusions

CAR co-expressed with LRP6 could sustain the memory phenotype that enabled permanent relief and may further assist in the development of potent and durable T-cell therapeutics.

Tumor neoantigen heterogeneity impacts bystander immune inhibition of pancreatic cancer growth

The immunogenic clonal-fraction threshold in heterogeneous solid-tumor required to induce effective bystander-killing of non-immunogenic subclones is unknown. Pancreatic cancer poses crucial challenges for immune therapeutic interventions due to low mutational-burden and consequent lack of neoantigens. Here, we designed a model to incorporate artificial-neoantigens into genes-of -interest in cancer-cells and to test their potential to actuate bystander-killing. By precisely controlling a neoantigen's abundance in the tumor, we studied the impact of neoantigen frequency on immune-response and immune-escape. Our results showed single, strong, widely-expressed neoantigen could lead to robust antitumor response when over 80% of cancer cells express the neoantigen. Further, immunological assays demonstrated T-cell responses against non-target self-antigen on KRAS-oncoprotein, when we inoculated animals with a high frequency of tumor-cells expressing test-neoantigen. Using nanoparticle-based gene-therapy, we successfully altered tumor-microenvironment by perturbing interleukin-12 and interleukin-10 gene-expression. The subsequent microenvironment-remodeling reduced the neoantigen frequency threshold at which bioluminescent signal intensity for tumor-burden decreased 1.5-log-fold, marking robust tumor-growth inhibition, from 83% to 29%. Our results thus suggest bystander killing is inefficient in immunologically-cold tumors like pancreatic-cancer and requires high neoantigen abundance. However, bystander killing mediated antitumor response can be rescued by adjuvant-immune therapy.

Escape From ALL-CARTaz: Leukemia Immunoediting in the Age of Chimeric Antigen Receptors

Chimeric antigen receptor (CAR) T-cell therapy has been transformative for the treatment of B-cell malignancies, with CD19- and CD22-directed CARs being prime examples. However, immunoediting and ensuing antigen loss remain the major obstacles to curative therapy in up to 25% of patients. For example, to achieve the CD19-negative phenotype, malignant cells can pick from a broad array of mechanisms, including focal loss-of-function mutations, dysregulated trafficking to the cell surface, alternative splicing, and lineage switching. In other cases, where resistance is mediated by insufficient antigen density, trogocytosis has been proposed as a possible underlying mechanism. To overcome these barriers, compensatory strategies will be needed, which could include using combinatorial CARs, harnessing epitope spreading, and targeting tumor neoantigens.

Adoptive Immunotherapy with Antigen-Specific T Cells Expressing a Native TCR

Although T cells genetically modified with chimeric antigen receptors became the first immune effector product to obtain FDA approval, T-cell products that recognize their antigenic targets through their native receptors have also produced encouraging responses. For instance, T cells recognizing immunogenic viral antigens are effective when infused in immunosuppressed patients. A large number of tumor antigens are also expressed on nonviral tumors, but these antigens are less immunogenic. Many tumors can evade a transferred immune response by producing variants, which have lost the targeted antigens, or inhibitory molecules that recruit suppressive cells, impeding persistence and function of immune effectors. Nevertheless, infusion of antigen-specific T cells has been well-tolerated, and clinical responses have been consistently associated with immune activity against tumor antigens and epitope spreading. To overcome some of the obstacles mentioned above, current research is focused on defining ex vivo culture conditions that promote in vivo persistence and activity of infused antigen-specific T cells. Combinations with immune checkpoint inhibitors or epigenetic modifiers to improve T-cell activity are also being evaluated in the clinic. Antigen-specific T cells may also be manufactured to overcome tumor evasion mechanisms by targeting multiple antigens and engineered to be resistant to inhibitory factors, such as TGFβ, or to produce the cytokines that are essential for T-cell expansion and sustained antitumor activity. Here, we discuss the use of T cells specific to tumor antigens through their native receptors and strategies under investigation to improve antitumor responses.