Accumulation of memory precursor CD8 T cells in regressing tumors following combination therapy with vaccine and anti-PD-1 antibody

Characterization of the Anti-Viral and Vaccine-Specific CD8+ T Cell Composition upon Treatment with the Cancer Vaccine VSV-GP

Numerous factors influence the magnitude and effector phenotype of vaccine-induced CD8+ T cells, thereby potentially impacting treatment efficacy. Here, we investigate the effect of vaccination dose, route of immunization, presence of a target antigen-expressing tumor, and heterologous prime-boost with peptide vaccine partner following vaccination with antigen-armed VSV-GP. Our results indicate that a higher vaccine dose increases antigen-specific CD8+ T cell proportions while altering the phenotype. The intravenous route induces the highest proportion of antigen-specific CD8+ T cells together with the lowest anti-viral response followed by the intraperitoneal, intramuscular, and subcutaneous routes. Moreover, the presence of a B16-OVA tumor serves as pre-prime, thereby increasing OVA-specific CD8+ T cells upon vaccination and thus altering the ratio of anti-tumor versus anti-viral CD8+ T cells. Interestingly, tumor-specific CD8+ T cells exhibit a different phenotype compared to bystander anti-viral CD8+ T cells. Finally, the heterologous combination of peptide and viral vaccine elicits the highest proportion of antigen-specific CD8+ T cells in the tumor and tumor-draining lymph nodes. In summary, we provide a basic immune characterization of various factors that affect anti-viral and vaccine target-specific CD8+ T cell proportions and phenotypes, thereby enhancing our vaccinology knowledge for future vaccine regimen designs.

Targeting mTOR and survivin concurrently potentiates radiation therapy in renal cell carcinoma by suppressing DNA damage repair and amplifying mitotic catastrophe

BACKGROUND

Renal cell carcinoma (RCC) was historically considered to be less responsive to radiation therapy (RT) compared to other cancer indications. However, advancements in precision high-dose radiation delivery through single-fraction and multi-fraction stereotactic ablative radiotherapy (SABR) have led to better outcomes and reduced treatment-related toxicities, sparking renewed interest in using RT to treat RCC. Moreover, numerous studies have revealed that certain therapeutic agents including chemotherapies can increase the sensitivity of tumors to RT, leading to a growing interest in combining these treatments. Here, we developed a rational combination of two radiosensitizers in a tumor-targeted liposomal formulation for augmenting RT in RCC. The objective of this study is to assess the efficacy of a tumor-targeted liposomal formulation combining the mTOR inhibitor everolimus (E) with the survivin inhibitor YM155 (Y) in enhancing the sensitivity of RCC tumors to radiation.

EXPERIMENTAL DESIGN

We slightly modified our previously published tumor-targeted liposomal formulation to develop a rational combination of E and Y in a single liposomal formulation (EY-L) and assessed its efficacy in RCC cell lines in vitro and in RCC tumors in vivo. We further investigated how well EY-L sensitizes RCC cell lines and tumors toward radiation and explored the underlying mechanism of radiosensitization.

RESULTS

EY-L outperformed the corresponding single drug-loaded formulations E-L and Y-L in terms of containing primary tumor growth and improving survival in an immunocompetent syngeneic mouse model of RCC. EY-L also exhibited significantly higher sensitization of RCC cells towards radiation in vitro than E-L and Y-L. Additionally, EY-L sensitized RCC tumors towards radiation therapy in xenograft and murine RCC models. EY-L mediated induction of mitotic catastrophe via downregulation of multiple cell cycle checkpoints and DNA damage repair pathways could be responsible for the augmentation of radiation therapy.

CONCLUSION

Taken together, our study demonstrated the efficacy of a strategic combination therapy in sensitizing RCC to radiation therapy via inhibition of DNA damage repair and a substantial increase in mitotic catastrophe. This combination therapy may find its use in the augmentation of radiation therapy during the treatment of RCC patients.

Regulation of Tumor Dendritic Cells by Programmed Cell Death 1 Pathways

The advent of immune checkpoint blockade therapy has revolutionized cancer treatments and is partly responsible for the significant decline in cancer-related mortality observed during the last decade. Immune checkpoint inhibitors, such as anti-programmed cell death 1 (PD-1)/programmed cell death ligand 1 (PD-L1), have demonstrated remarkable clinical successes in a subset of cancer patients. However, a considerable proportion of patients remain refractory to immune checkpoint blockade, prompting the exploration of mechanisms of treatment resistance. Whereas much emphasis has been placed on the role of PD-L1 and PD-1 in regulating the activity of tumor-infiltrating T cells, recent studies have now shown that this immunoregulatory axis also directly regulates myeloid cell activity in the tumor microenvironment including tumor-infiltrating dendritic cells. In this review, I discuss the most recent advances in the understanding of how PD-1, PD-L1, and programmed cell death ligand 2 regulate the function of tumor-infiltrating dendritic cells, emphasizing the need for further mechanistic studies that could facilitate the development of novel combination immunotherapies for improved cancer patient benefit.

Current status and future of cancer vaccines: A bibliographic study

Background

Cancer vaccines are an important component of tumour immunotherapy. An increasing number of studies have shown that cancer vaccines have considerable clinical benefits. With the development of tumour precision medicine, cancer vaccines have become important because of their individualised targeting effects. However, few bibliometric studies have conducted comprehensive systematic reviews in this field. This study aimed to assess the scientific output and trends in cancer vaccine research from a global perspective.

Methods

We collected publications on cancer vaccines from the Web of Science Core Collection database, which was limited to articles and reviews in English. Microsoft Excel, VOS Viewer, and CiteSpace V were used for quantitative and visual analyses.

Results

A total of 7807 articles were included. From 1991 to 2022, the number of publications increased annually. The United States had the highest number of articles published in this field (48.28 %), the highest citation frequency (183,964 times), and the highest H-index (182). The National Institutes of Health topped the list with 476 articles. Schlom J had the highest number of published articles (128) and was the main investigator in this field. The journal, Cancer Immunology Immunotherapy, had published the highest number of articles in related fields. In recent years, tumour microenvironment, immune checkpoint inhibitors, particle vaccines, tumour antigens, and dendritic cells have become research hotspots related to cancer vaccines.

Conclusion

Cancer vaccines are a popular research topic in the field of tumour immunotherapy. Related research and publications will enter a boom stage. "Immune checkpoint inhibitors", "tumour microenvironment" and "dendritic cells" may become future research hotspots, while "T-cell suppressor" is a potential puzzle to be solved.

Eribulin promotes proliferation of CD8+ T cells and potentiates T cell-mediated anti-tumor activity against triple-negative breast cancer cells

PURPOSE

Chemotherapeutic agents exert immunomodulatory effects on triple-negative breast cancer (TNBC) cells and immune cells. Eribulin favorably affects the immunological status of patients with breast cancer. However, the effects of eribulin on the immune cells remain unexplored. The aim of this study was to investigate the effects of eribulin on immune cells.

METHODS

Peripheral blood mononuclear cells (PBMCs) from healthy donors and mouse splenocytes were stimulated with anti-CD3 and anti-CD28 antibodies. The effects of eribulin and paclitaxel on cell proliferation and differentiation status were analyzed using flow cytometry. RNA sequencing was performed to assess alterations in gene expression in CD8+ T cells following eribulin and paclitaxel treatment. Using TNBC cell lines (MDA-MB-231, Hs578T, and MDA-MB-157), the anti-tumor activity of CD3/CD28-stimulated T cells combined with eribulin or paclitaxel was evaluated.

RESULTS

Eribulin did not affect CD3/CD28-stimulated PBMCs proliferation. However, eribulin significantly decreased the CD4/CD8 ratio in T cells, indicating that eribulin facilitates CD8+ T cell proliferation. Furthermore, eribulin significantly increased the frequency of less differentiated CD45RA+, CCR7+, and TCF1+ subsets of CD8+ T cells. RNA sequencing revealed that eribulin enhanced the expression of gene sets related to cell proliferation and immune responses. Moreover, eribulin augmented the anti-tumor effects of CD3/CD28-stimulated T cells against TNBC cells. These results were not observed in experiments using paclitaxel.

CONCLUSIONS

Eribulin promoted CD8+ T cell proliferation, repressed effector T cell differentiation, and harnessed T cell-mediated anti-tumor effects. These mechanisms may be one of the cues that eribulin can improve the immunological status of tumor-bearing hosts.

Th17-inducing dendritic cell vaccines stimulate effective CD4 T cell-dependent antitumor immunity in ovarian cancer that overcomes resistance to immune checkpoint blockade

BACKGROUND

Ovarian cancer (OC), a highly lethal cancer in women, has a 48% 5-year overall survival rate. Prior studies link the presence of IL-17 and Th17 T cells in the tumor microenvironment to improved survival in OC patients. To determine if Th17-inducing vaccines are therapeutically effective in OC, we created a murine model of Th17-inducing dendritic cell (DC) (Th17-DC) vaccination generated by stimulating IL-15 while blocking p38 MAPK in bone marrow-derived DCs, followed by antigen pulsing.

METHODS

ID8 tumor cells were injected intraperitoneally into mice. Mice were treated with Th17-DC or conventional DC (cDC) vaccine alone or with immune checkpoint blockade (ICB). Systemic immunity, tumor associated immunity, tumor size and survival were examined using a variety of experimental strategies.

RESULTS

Th17-DC vaccines increased Th17 T cells in the tumor microenvironment, reshaped the myeloid microenvironment, and improved mouse survival compared with cDC vaccines. ICB had limited efficacy in OC, but Th17-inducing DC vaccination sensitized it to anti-PD-1 ICB, resulting in durable progression-free survival by overcoming IL-10-mediated resistance. Th17-DC vaccine efficacy, alone or with ICB, was mediated by CD4 T cells, but not CD8 T cells.

CONCLUSIONS

These findings emphasize using biologically relevant immune modifiers, like Th17-DC vaccines, in OC treatment to reshape the tumor microenvironment and enhance clinical responses to ICB therapy.

Bidirectional crosstalk between therapeutic cancer vaccines and the tumor microenvironment: Beyond tumor antigens

Immunotherapy has rejuvenated cancer therapy, especially after anti-PD-(L)1 came onto the scene. Among the many therapeutic options, therapeutic cancer vaccines are one of the most essential players. Although great progress has been made in research on tumor antigen vaccines, few phase III trials have shown clinical benefits. One of the reasons lies in obstruction from the tumor microenvironment (TME). Meanwhile, the therapeutic cancer vaccine reshapes the TME in an ambivalent way, leading to immune stimulation or immune escape. In this review, we summarize recent progress on the interaction between therapeutic cancer vaccines and the TME. With respect to vaccine resistance, innate immunosuppressive TME components and acquired resistance caused by vaccination are both involved. Understanding the underlying mechanism of this crosstalk provides insight into the treatment of cancer by directly targeting the TME or synergizing with other therapeutics.

Anti-HVEM mAb therapy improves antitumoral immunity both in vitro and in vivo, in a novel transgenic mouse model expressing human HVEM and BTLA molecules challenged with HVEM expressing tumors

BACKGROUND

Tumor necrosis factor superfamily member 14 (TNFRSF14)/herpes virus entry mediator (HVEM) is the ligand for B and T lymphocyte attenuator (BTLA) and CD160-negative immune co-signaling molecules as well as viral proteins. Its expression is dysregulated with an overexpression in tumors and a connection with tumors of adverse prognosis.

METHODS

We developed C57BL/6 mouse models co-expressing human (hu)BTLA and huHVEM as well as antagonistic monoclonal antibodies (mAbs) that completely prevent the interactions of HVEM with its ligands.

RESULTS

Here, we show that the anti-HVEM18-10 mAb increases primary human αβ-T cells activity alone (CIS-activity) or in the presence of HVEM-expressing lung or colorectal cancer cells in vitro (TRANS-activity). Anti-HVEM18-10 synergizes with antiprogrammed death-ligand 1 (anti-PD-L1) mAb to activate T cells in the presence of PD-L1-positive tumors, but is sufficient to trigger T cell activation in the presence of PD-L1-negative cells. In order to better understand HVEM18-10 effects in vivo and especially disentangle its CIS and TRANS effects, we developed a knockin (KI) mouse model expressing human BTLA (huBTLA^+/+) and a KI mouse model expressing both huBTLA^+/+/huHVEM^+/+ (double KI (DKI)). In vivo preclinical experiments performed in both mouse models showed that HVEM18-10 treatment was efficient to decrease human HVEM⁺ tumor growth. In the DKI model, anti-HVEM18-10 treatment induces a decrease of exhausted CD8⁺ T cells and regulatory T cells and an increase of effector memory CD4⁺ T cells within the tumor. Interestingly, mice which completely rejected tumors (±20%) did not develop tumors on rechallenge in both settings, therefore showing a marked T cell-memory phenotype effect.

CONCLUSIONS

Altogether, our preclinical models validate anti-HVEM18-10 as a promising therapeutic antibody to use in clinics as a monotherapy or in combination with existing immunotherapies (antiprogrammed cell death protein 1/anti-PD-L1/anti-cytotoxic T-lymphocyte antigen-4 (CTLA-4)).

Role of LGMN in tumor development and its progression and connection with the tumor microenvironment

Legumain (LGMN) has been demonstrated to be overexpressed not just in breast, prostatic, and liver tumor cells, but also in the macrophages that compose the tumor microenvironment. This supports the idea that LGMN is a pivotal protein in regulating tumor development, invasion, and dissemination. Targeting LGMN with siRNA or chemotherapeutic medicines and peptides can suppress cancer cell proliferation in culture and reduce tumor growth in vivo. Furthermore, legumain can be used as a marker for cancer detection and targeting due to its expression being significantly lower in normal cells compared to tumors or tumor-associated macrophages (TAMs). Tumor formation is influenced by aberrant expression of proteins and alterations in cellular architecture, but the tumor microenvironment is a crucial deciding factor. Legumain (LGMN) is an in vivo-active cysteine protease that catalyzes the degradation of numerous proteins. Its precise biological mechanism encompasses a number of routes, including effects on tumor-associated macrophage and neovascular endothelium in the tumor microenvironment. The purpose of this work is to establish a rationale for thoroughly investigating the function of LGMN in the tumor microenvironment and discovering novel tumor early diagnosis markers and therapeutic targets by reviewing the function of LGMN in tumor genesis and progression and its relationship with tumor milieu.

Phase I/II study of multipeptide cancer vaccine IMA901 after single-dose cyclophosphamide in Japanese patients with advanced renal cell cancer with long-term follow up

BACKGROUND

IMA901 is the first therapeutic vaccine for renal cell cancer (RCC). It contains multiple tumor-associated peptides (TUMAPs) that are naturally present in human cancers.

METHODS

In a phase I/II study, we treated a total of 10 Japanese patients with advanced RCC who were human leukocyte antigen A (HLA-A)*02 +. Vaccination involved i.d. injection of GM-CSF (75 μg), followed within 15-30 min by i.d. injection of IMA901 (containing 413 μg of each peptide). No treatment with either anticancer agents or immunosuppressants was allowed within 4 weeks before entering the trial. Patients were scheduled to receive 7 vaccinations during the first 5 weeks of treatment (induction period), followed by 10 further vaccinations at 3-week intervals for up to 30 weeks (maintenance period). The primary endpoints were safety and tolerability, while the secondary endpoints were PFS, OS, and immunogenicity.

RESULTS

There were no treatment-related serious adverse events or deaths during the study period. When the response was assessed after 4 months, 10% of patients showed a partial response, 80% had stable disease, and 10% had progressive disease. Among patients in whom the T-cell response was analyzed, five patients showed a vaccine-induced T-cell response against at least one HLA class I-restricted TUMAP and two patients had T-cell responses to multiple TUMAPs. PFS was 5.5 months and OS was 18 months.

CONCLUSIONS

This study demonstrated the safety and tolerability of IMA901 vaccine in Japanese RCC patients, and also showed that vaccination elicited an immune response.

Screening of the novel immune-suppressive biomarkers of TMED family and whether knockdown of TMED2/3/4/9 inhibits cell migration and invasion in breast cancer

Background

Transmembrane p24 trafficking protein (TMED) family members are implicated in several solid tumors, but their clinical relevance for breast cancer (BC) remains unclear. This study aimed to probe their prognostic values and relations with tumor immunity in BC.

Methods

TMED family mRNA expression was assessed in five microarray datasets (GSE65212, GSE42568, GSE5364, GSE22820 and GSE45827) from Gene Expression Omnibus (GEO) database and invasive breast cancer (BRCA) cohort from The Cancer Genome Atlas (TCGA). Receiver operating characteristic (ROC) curve was performed to determine the predictive values of filtered members of the TMED family. The protein expressions of screen genes were validated by Clinical Proteomic Tumor Analysis Consortium (CPTAC) data from University of ALabama at Birmingham CANcer data analysis portal (UALCAN) and detected in the clinical specimens by western blot assay. Clinicopathologic variables were analyzed with bc-GenExMiner, and patient prognostic data were obtained with Kaplan-Meier Plotter. In vitro wound healing and invasion assays were performed on siRNA-transfected BC cell lines. TIMER 2.0, SangerBox, and ImmPort were used to evaluate tumor immune infiltration, immune checkpoints, and other immune-related genes. CbioPortal, Metascape, Expression2kinases, and LinkedOmics were used to explore gene regulatory network.

Results

BC tissues expressed TMED2/3/4/9 at a higher level than normal tissues, providing diagnostic potential. All the areas under the ROC curve for TMED2/3/4/9 were more than 0.7. TMED2/3/4/9 correlated with numerous clinical variables, including lymph node status, Scarff-Bloom-Richardson score (SBR), Nottingham Prognostic Index (NPI), estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER-2), and triple-negative breast cancer (TNBC) status, and their high expression predicted the poor prognosis of BC patients. TMED2/3/4/9 knockdown drastically inhibited the migratory and invasive capacities of MDA-MB-231 and HCC1937 cells. TMED2/3/4/9 expressions correlated negatively with the infiltration of tumor-suppressive immune cells such as CD8⁺ T cells, dendritic cells, and natural killer cells, and was inversely related to a variety of immune checkpoint genes, including programmed cell death 1 (PD-1) and cytotoxic T-lymphocyte associated protein 4 (CTLA4). A set of kinases, transcription factors, and microRNAs (miRNAs) may regulate TMED2/3/4/9 abnormalities at the genome level.

Conclusions

TMED2/3/4/9 may serve as diagnostic, prognostic, and immune-suppressive biomarkers in BC.

Cell atlas of the immune microenvironment in gastrointestinal cancers: Dendritic cells and beyond

Gastrointestinal (GI) cancers occur in the alimentary tract and accessory organs. They exert a global burden with high morbidity and mortality. Inside the tumor microenvironment, dendritic cells (DCs) are the most efficient antigen-presenting cells and are necessary for adaptive immune responses such as T and B-cell maturation. However, the subsets of DCs revealed before were mostly based on flow cytometry and bulk sequencing. With the development of single-cell RNA sequencing (scRNA-seq), the tumor and microenvironment heterogeneity of GI cancer has been illustrated. In this review, we summarize the classification and development trajectory of dendritic cells at the single-cell level in GI cancer. Additionally, we focused on the interaction of DCs with T cells and their effect on the response to immunotherapy. Specifically, we focused on the newly identified tumor-infiltrating dendritic cells and discuss their potential function in antitumor immunity.

Protein kinase Cι mediates immunosuppression in lung adenocarcinoma

Lung adenocarcinoma (LUAD) is the most prevalent form of non-small cell lung cancer (NSCLC) and a leading cause of cancer death. Immune checkpoint inhibitors (ICIs) of programmed death-1/programmed death-ligand 1 (PD-1/PD-L1) signaling induce tumor regressions in a subset of LUAD, but many LUAD tumors exhibit resistance to ICI therapy. Here, we identified Prkci as a major determinant of response to ICI in a syngeneic mouse model of oncogenic mutant Kras/Trp53 loss (KP)-driven LUAD. Protein kinase Cι (PKCι)-dependent KP tumors exhibited resistance to anti-PD-1 antibody therapy (α-PD-1), whereas KP tumors in which Prkci was genetically deleted (KPI tumors) were highly responsive. Prkci-dependent resistance to α-PD-1 was characterized by enhanced infiltration of myeloid-derived suppressor cells (MDSCs) and decreased infiltration of CD8+ T cells in response to α-PD-1. Mechanistically, Prkci regulated YAP1-dependent expression of Cxcl5, which served to attract MDSCs to KP tumors. The PKCι inhibitor auranofin inhibited KP tumor growth and sensitized these tumors to α-PD-1, whereas expression of either Prkci or its downstream effector Cxcl5 in KPI tumors induced intratumoral infiltration of MDSCs and resistance to α-PD-1. PRKCI expression in tumors of patients with LUAD correlated with genomic signatures indicative of high YAP1-mediated transcription, elevated MDSC infiltration and low CD8+ T cell infiltration, and with elevated CXCL5/6 expression. Last, PKCι-YAP1 signaling was a biomarker associated with poor response to ICI in patients with LUAD. Our data indicate that immunosuppressive PKCι-YAP1-CXCL5 signaling is a key determinant of response to ICI, and pharmacologic inhibition of PKCι may improve therapeutic response to ICI in patients with LUAD.

The depths of PD-1 function within the tumor microenvironment beyond CD8+ T cells

Programmed cell death-1 (PD-1; CD279) is a cell surface receptor that is expressed in both innate and adaptive immune cells. The role of PD-1 in adaptive immune cells, specifically in CD8+ T cells, has been thoroughly investigated but its significance in other immune cells is yet to be well established. This review will address the role of PD-1 based therapies in enhancing non-CD8+ T cell immune responses within cancer. Specifically, the expression and function of PD-1 in non-CD8+ immune cell compartments such as CD4+ T helper cell subsets, myeloid cells and innate lymphoid cells (ILCs) will be discussed. By understanding the immune cell specific function of PD-1 within tissue resident innate and adaptive immune cells, it will be possible to stratify patients for PD-1 based therapies for both immunogeneic and non-immunogeneic neoplastic disorders. With this knowledge from fundamental and translational studies, PD-1 based therapies can be utilized to enhance T cell independent immune responses in cancers.

Immunotherapy for advanced hepatocellular carcinoma: From clinical trials to real-world data and future advances

Hepatocellular carcinoma (HCC) is a leading cause of cancer-associated mortality worldwide. HCC is an inflammation-associated immunogenic cancer that frequently arises in chronically inflamed livers. Advanced HCC is managed with systemic therapies; the tyrosine kinase inhibitor (TKI) sorafenib has been used in 1st-line setting since 2007. Immunotherapies have emerged as promising treatments across solid tumors including HCC for which immune checkpoint inhibitors (ICIs) are licensed in 1st- and 2nd-line treatment setting. The treatment field of advanced HCC is continuously evolving. Several clinical trials are investigating novel ICI candidates as well as new ICI regimens in combination with other therapeutic modalities including systemic agents, such as other ICIs, TKIs, and anti-angiogenics. Novel immunotherapies including adoptive cell transfer, vaccine-based approaches, and virotherapy are also being brought to the fore. Yet, despite advances, several challenges persist. Lack of real-world data on the use of immunotherapy for advanced HCC in patients outside of clinical trials constitutes a main limitation hindering the breadth of application and generalizability of data to this larger and more diverse patient cohort. Consequently, issues encountered in real-world practice include patient ineligibly for immunotherapy because of contraindications, comorbidities, or poor performance status; lack of response, efficacy, and safety data; and cost-effectiveness. Further real-world data from high-quality large prospective cohort studies of immunotherapy in patients with advanced HCC is mandated to aid evidence-based clinical decision-making. This review provides a critical and comprehensive overview of clinical trials and real-world data of immunotherapy for HCC, with a focus on ICIs, as well as novel immunotherapy strategies underway.

Hyperprogression, a challenge of PD-1/PD-L1 inhibitors treatments: potential mechanisms and coping strategies

Immunotherapy is now a mainstay in cancer treatments. Programmed cell death 1 (PD-1)/programmed cell death ligand 1 (PD-L1) immune checkpoint inhibitor (ICI) therapies have opened up a new venue of advanced cancer immunotherapy. However, hyperprogressive disease (HPD) induced by PD-1/PD-L1 inhibitors caused a significant decrease in the overall survival (OS) of the patients, which compromise the efficacy of PD-1/PD-L1 inhibitors. Therefore, HPD has become an urgent issue to be addressed in the clinical uses of PD-1/PD-L1 inhibitors. The mechanisms of HPD remain unclear, and possible predictive factors of HPD are not well understood. In this review, we summarized the potential mechanisms of HPD and coping strategies that can effectively reduce the occurrence and development of HPD.

DNA immunotherapy targeting BARF1 induces potent anti-tumor responses against Epstein-Barr-virus-associated carcinomas

Latent Epstein-Barr virus (EBV) infection is associated with several types of cancer. Several clinical studies have targeted EBV antigens as immune therapeutic targets with limited efficacy of EBV malignancies, suggesting that additional targets might be important. BamHI-A rightward frame 1 (BARF1) is an EBV antigen that is highly expressed in EBV+ nasopharyngeal carcinoma (NPC) and EBV-associated gastric carcinoma (EBVaGC). BARF1 antigen can transform human epithelial cells in vivo. BARF1-specific antibodies and cytotoxic T cells were detected in some EBV+ NPC patients. However, BARF1 has not been evaluated as an antigen in the context of therapeutic immunization. Its possible importance in this context is unclear. Here, we developed a synthetic-DNA-based expression cassette as immunotherapy targeting BARF1 (pBARF1). Immunization with pBARF1 induced potent antigen-specific humoral and T cell responses in vivo. Immunization with pBARF1 plasmid impacted tumor progression through the induction of CD8+ T cells in novel BARF1+ carcinoma models. Using an in vivo imaging system, we observed that pBARF1-immunized animals rapidly cleared cancer cells. We demonstrated that pBARF1 can induce antigen-specific immune responses that can impact cancer progression. Further study of this immune target is likely important as part of therapeutic approaches for EBV+ malignancies.

Personalized therapy with peptide-based neoantigen vaccine (EVX-01) including a novel adjuvant, CAF®09b, in patients with metastatic melanoma

The majority of neoantigens arise from unique mutations that are not shared between individual patients, making neoantigen-directed immunotherapy a fully personalized treatment approach. Novel technical advances in next-generation sequencing of tumor samples and artificial intelligence (AI) allow fast and systematic prediction of tumor neoantigens. This study investigates feasibility, safety, immunity, and anti-tumor potential of the personalized peptide-based neoantigen vaccine, EVX-01, including the novel CD8⁺ T-cell inducing adjuvant, CAF®09b, in patients with metastatic melanoma (NTC03715985). The AI platform PIONEER^TM was used for identification of tumor-derived neoantigens to be included in a peptide-based personalized therapeutic cancer vaccine. EVX-01 immunotherapy consisted of 6 administrations with 5–10 PIONEER^TM-predicted neoantigens as synthetic peptides combined with the novel liposome-based Cationic Adjuvant Formulation 09b (CAF®09b) to strengthen T-cell responses. EVX-01 was combined with immune checkpoint inhibitors to augment the activity of EVX-01-induced immune responses. The primary endpoint was safety, exploratory endpoints included feasibility, immunologic and objective responses. This interim analysis reports the results from the first dose-level cohort of five patients. We documented a short vaccine manufacturing time of 48–55 days which enabled the initiation of EVX-01 treatment within 60 days from baseline biopsy. No severe adverse events were observed. EVX-01 elicited long-lasting EVX-01-specific T-cell responses in all patients. Competitive manufacturing time was demonstrated. EVX-01 was shown to be safe and able to elicit immune responses targeting tumor neoantigens with encouraging early indications of a clinical and meaningful antitumor efficacy, warranting further study.

Antitumor Peptide-Based Vaccine in the Limelight

The success of the immune checkpoint blockade has provided a proof of concept that immune cells are capable of attacking tumors in the clinic. However, clinical benefit is only observed in less than 20% of the patients due to the non-specific activation of immune cells by the immune checkpoint blockade. Developing tumor-specific immune responses is a challenging task that can be achieved by targeting tumor antigens to generate tumor-specific T-cell responses. The recent advancements in peptide-based immunotherapy have encouraged clinicians and patients who are struggling with cancer that is otherwise non-treatable with current therapeutics. By selecting appropriate epitopes from tumor antigens with suitable adjuvants, peptides can elicit robust antitumor responses in both mice and humans. Although recent experimental data and clinical trials suggest the potency of tumor reduction by peptide-based vaccines, earlier clinical trials based on the inadequate hypothesis have misled that peptide vaccines are not efficient in eliminating tumor cells. In this review, we highlighted the recent evidence that supports the rationale of peptide-based antitumor vaccines. We also discussed the strategies to select the optimal epitope for vaccines and the mechanism of how adjuvants increase the efficacy of this promising approach to treat cancer.

Targeting LAG3/GAL-3 to overcome immunosuppression and enhance anti-tumor immune responses in multiple myeloma

Immune profiling in patients with monoclonal gammopathy of undetermined significance (MGUS), smoldering multiple myeloma (SMM), and multiple myeloma (MM) provides the framework for developing novel immunotherapeutic strategies. Here, we demonstrate decreased CD4⁺ Th cells, increased Treg and G-type MDSC, and upregulation of immune checkpoints on effector/regulatory and CD138⁺ cells in MM patients, compared MGUS/SMM patients or healthy individuals. Among the checkpoints profiled, LAG3 was most highly expressed on proliferating CD4⁺ Th and CD8⁺ Tc cells in MM patients BMMC and PBMC. Treatment with antibody targeting LAG3 significantly enhanced T cells proliferation and activities against MM. XBP1/CD138/CS1-specific CTL generated in vitro displayed anti-MM activity, which was further enhanced following anti-LAG3 treatment, within the antigen-specific memory T cells. Treg and G-type MDSC weakly express LAG3 and were minimally impacted by anti-LAG3. CD138⁺ MM cells express GAL-3, a ligand for LAG3, and anti-GAL-3 treatment increased MM-specific responses, as observed for anti-LAG3. Finally, we demonstrate checkpoint inhibitor treatment evokes non-targeted checkpoints as a cause of resistance and propose combination therapeutic strategies to overcome this resistance. These studies identify and validate blockade of LAG3/GAL-3, alone or in combination with immune strategies including XBP1/CD138/CS1 multipeptide vaccination, to enhance anti-tumor responses and improve patient outcome in MM.

Identification of a Six-Gene Prognostic Signature Characterized by Tumor Microenvironment Immune Profiles in Clear Cell Renal Cell Carcinoma

Clear cell renal cell carcinoma (ccRCC) is widely acknowledged to be extremely sensitive to immunotherapy, emphasizing the tremendous impacts on which the tumor microenvironment (TME) has shown. However, the molecular subgroups characterized by the TME features scarcely serve as the risk stratification guides in clinical practice for survival outcomes and immunotherapy response prediction. This study generated fresh insights into a novel TME-related prognostic signature derived from The Cancer Genome Atlas database using integrated bioinformatics analyses. Subsequently, Kaplan–Meier survival analysis, receiver operating characteristic analysis, and univariate and multivariate Cox regression analysis were performed to evaluate and validate the efficacy and the accuracy of the signature in ccRCC prognosis. Furthermore, we discovered that the risk score presented an increased likelihood of correlation with miscellaneous clinicopathological characteristics, natural killer cell-mediated cytotoxicity, immune cell infiltration levels, and immune checkpoint expression. These findings highlighted the notion that the six-gene signature characterized by the TME features may have implications on the risk stratification for personalized and precise immunotherapeutic management.

Anti-PD1 antibody enhances the anti-tumor efficacy of MUC1-MBP fusion protein vaccine via increasing Th1, Tc1 activity and decreasing the proportion of MDSC in the B16-MUC1 melanoma mouse model

In previous studies, we have obtained a notable anti-tumor efficacy of the recombinant MUC1-MBP vaccine in the process of mouse B16-MUC1 melanoma treatment. However, the tumor cannot be eliminated completely. We found that the tumor inhibition rate decreased from 81.67% (five immunizations) to 43.67% (eight immunizations) after more than five immunizations, indicating persistent vaccine stimulation may activate immunosuppressive factors. In the present study, we revealed that programmed cell death 1 (PD1), an inhibitory molecule suppressing T cell function, expressed on splenic and tumor-infiltrating T cells were up-regulated by the vaccine. Therefore, to optimize the anti-tumor efficacy of the vaccine, we employed combination immunotherapy with MUC1-MBP vaccine and αPD1 (anti-PD1 antibody). Results showed that combination immunotherapy induced a more remarkable anti-tumor efficacy, the tumor clearance being increased to 80% from 20% which obtain by MUC1-MBP vaccine immunizations. To investigate the possible underlying mechanism, IFN-γ secretion and cytotoxic T lymphocyte (CTL) cytotoxicity were measured by enzyme-linked immunosorbent assay (ELISA) and xCELLigence real-time cell analyzer (RTCA) respectively. T cell subsets and immunosuppressive cells in the mouse spleen and tumor microenvironment were analyzed by FACS. Results showed that the proportion of splenic CD8⁺T cells and tumor infiltration was increased and the activity of CTL killing, T helper 1 (Th1), Type 1 CD8⁺T (Tc1) was enhanced, indicating that the anti-tumor efficacy enhanced by combination immunotherapy was mainly through boosting CD8⁺T cells mediated anti-tumor cellular immunity. Additionally, combination immunotherapy significantly decreased the splenic and tumor-infiltrating myeloid derived suppressor cells (MDSCs). These results demonstrated that combination immunotherapy with MUC1-MBP vaccine and αPD1 was capable to invoke a more potent anti-tumor immune response and provide a foundation for further research.

Implantable optical fibers for immunotherapeutics delivery and tumor impedance measurement

Immune checkpoint blockade antibodies have promising clinical applications but suffer from disadvantages such as severe toxicities and moderate patient-response rates. None of the current delivery strategies, including local administration aiming to avoid systemic toxicities, can sustainably supply drugs over the course of weeks; adjustment of drug dose, either to lower systemic toxicities or to augment therapeutic response, is not possible. Herein, we develop an implantable miniaturized device using electrode-embedded optical fibers with both local delivery and measurement capabilities over the course of a few weeks. The combination of local immune checkpoint blockade antibodies delivery via this device with photodynamic therapy elicits a sustained anti-tumor immunity in multiple tumor models. Our device uses tumor impedance measurement for timely presentation of treatment outcomes, and allows modifications to the delivered drugs and their concentrations, rendering this device potentially useful for on-demand delivery of potent immunotherapeutics without exacerbating toxicities.

The Clinical Application of Neoantigens in Esophageal Cancer

Esophageal cancer (EC) is a common malignant tumor with poor prognosis, and current treatments for patients with advanced EC remain unsatisfactory. Recently, immunotherapy has been recognized as a new and promising approach for various tumors. EC cells present a high tumor mutation burden and harbor abundant tumor antigens, including tumor-associated antigens and tumor-specific antigens. The latter, also referred to as neoantigens, are immunogenic mutated peptides presented by major histocompatibility complex class I molecules. While current genomics and bioinformatics technologies have greatly facilitated the identification of tumor neoantigens, identifying individual neoantigens systematically for successful therapies remains a challenging problem. Owing to the initiation of strong, specific tumor-killing cytotoxic T cell responses, neoantigens are emerging as promising targets to develop personalized treatment and have triggered the development of cancer vaccines, adoptive T cell therapies, and combination therapies. This review aims to give a current understanding of the clinical application of neoantigens in EC and provide direction for future investigation.

Characterization of neoantigen-specific T cells in cancer resistant to immune checkpoint therapies

Strongly implicated in effective antitumor immune responses, tumor mutation–derived antigens, or neoantigens, are one of the main targets for cancer vaccines despite uncertainty of the efficacy of this approach. Using a high-throughput screening method, we identify an endogenously immunogenic neoantigen in a commonly used mouse lung tumor model. We also found that the endogenous CD8 T cells specific for this neoantigen expand greatly upon treatment with immune checkpoint inhibitors or vaccination despite the lack of associated tumor regression in this model. In addition to informing neoantigen vaccination strategies and providing an accessible system for testing alternative therapeutics, our results provide insights into the mechanisms for the lack of response observed for a majority of patients treated with checkpoint blockade immunotherapies.

Neoantigen-specific T cells are strongly implicated as being critical for effective immune checkpoint blockade treatment (ICB) (e.g., anti–PD-1 and anti–CTLA-4) and are being targeted for vaccination-based therapies. However, ICB treatments show uneven responses between patients, and neoantigen vaccination efficiency has yet to be established. Here, we characterize neoantigen-specific CD8⁺ T cells in a tumor that is resistant to ICB and neoantigen vaccination. Leveraging the use of mass cytometry combined with multiplex major histocompatibility complex (MHC) class I tetramer staining, we screened and identified tumor neoantigen–specific CD8⁺ T cells in the Lewis Lung carcinoma (LLC) tumor model (mRiok1). We observed an expansion of mRiok1-specific CD8⁺ tumor-infiltrating lymphocytes (TILs) after ICB targeting PD-1 or CTLA-4 with no sign of tumor regression. The expanded neoantigen-specific CD8⁺ TILs remained phenotypically and functionally exhausted but displayed cytotoxic characteristics. When combining both ICB treatments, mRiok1-specific CD8⁺ TILs showed a stem-like phenotype and a higher capacity to produce cytokines, but tumors did not show signs of regression. Furthermore, combining both ICB treatments with neoantigen vaccination did not induce tumor regression either despite neoantigen-specific CD8⁺ TIL expansion. Overall, this work provides a model for studying neoantigens in an immunotherapy nonresponder model. We showed that a robust neoantigen-specific T-cell response in the LLC tumor model could fail in tumor response to ICB, which will have important implications in designing future immunotherapeutic strategies.

Characterization and ex vivo expansion of rare in situ cytokine secreting T cell populations from tumor tissue and blood of oral squamous cell carcinoma patients

Rare subpopulations of tumor antigen-reactive memory T cells, which actively secrete type-1 effector cytokines, particularly TNF-α in situ, possess anti-tumor activity and prognostic relevance. These cells are relevant for cancer immunotherapy; however, their low frequencies make them difficult to study and novel protocols for their culture and expansion ex vivo are needed. Here, we studied the presence of T cells secreting type-1 cytokines (Cy⁺T cells) in the blood and tumors of 24 patients with oral squamous cell carcinomas (OSCC) and explored possibilities for their isolation and expansion. More than 90% of OSCC patients contained enriched numbers Cy⁺T cells in the blood and tumors compared to healthy donors in which these were hardly detectable. The majority of TNF-α⁺T cells were CD4⁺ T helper cells while IFN-γ⁺TIL were predominantly CD8⁺. Cy⁺T helper cells in the blood were early-differentiated memory T cells while Cy⁺TIL and Cy⁺CD8⁺T cells showed advanced-differentiated memory T cell phenotypes. We explored different conditions for their in vitro culture and found that Cy⁺T cells can be efficiently expanded in vitro to similar levels as Cy^-T cells and after expansion maintained their TNF-α secreting capacity. However, for optimal expansion they required specific culture conditions to support the maintenance of stem-like and central memory T cell phenotype. In conclusion, we show that Cy⁺T cells are enriched in OSCC patients and report a novel cell culture protocol optimized to specifically expand and functionally maintain these cells for further functional characterization or for their exploitation in immunotherapy of OSCC.

Cancer Vaccines, Adjuvants, and Delivery Systems

Vaccination was first pioneered in the 18th century by Edward Jenner and eventually led to the development of the smallpox vaccine and subsequently the eradication of smallpox. The impact of vaccination to prevent infectious diseases has been outstanding with many infections being prevented and a significant decrease in mortality worldwide. Cancer vaccines aim to clear active disease instead of aiming to prevent disease, the only exception being the recently approved vaccine that prevents cancers caused by the Human Papillomavirus. The development of therapeutic cancer vaccines has been disappointing with many early cancer vaccines that showed promise in preclinical models often failing to translate into efficacy in the clinic. In this review we provide an overview of the current vaccine platforms, adjuvants and delivery systems that are currently being investigated or have been approved. With the advent of immune checkpoint inhibitors, we also review the potential of these to be used with cancer vaccines to improve efficacy and help to overcome the immune suppressive tumor microenvironment.

Therapeutic applications of the cancer immunoediting hypothesis

Since the late 19th century, the immune system has increasingly garnered interest as a novel avenue for cancer therapy, particularly given scientific breakthroughs in recent decades delineating the fundamental role of the immune system in tumorigenesis. The immunoediting hypothesis has articulated this role, describing three phases of the tumor-immune system interaction: Elimination, Equilibrium, and Escape wherein tumors progress from active immunologic surveillance and destruction through dynamic immunologic stasis to unfettered growth. The primary goals of immunotherapy are to restrict and revert progression through these phases, thereby improving the immune system's ability to control tumor growth. In this review, we detail the development and foundation of the cancer immunoediting hypothesis and apply this hypothesis to the dynamic immunotherapy field that includes checkpoint blockade, vaccine therapy, and adoptive cell transfer.

Cancer Vaccines: Adjuvant Potency, Importance of Age, Lifestyle, and Treatments

Although the discovery and characterization of multiple tumor antigens have sparked the development of many antigen/derived cancer vaccines, many are poorly immunogenic and thus, lack clinical efficacy. Adjuvants are therefore incorporated into vaccine formulations to trigger strong and long-lasting immune responses. Adjuvants have generally been classified into two categories: those that ‘depot’ antigens (e.g. mineral salts such as aluminum hydroxide, emulsions, liposomes) and those that act as immunostimulants (Toll Like Receptor agonists, saponins, cytokines). In addition, several novel technologies using vector-based delivery of antigens have been used. Unfortunately, the immune system declines with age, a phenomenon known as immunosenescence, and this is characterized by functional changes in both innate and adaptive cellular immunity systems as well as in lymph node architecture. While many of the immune functions decline over time, others paradoxically increase. Indeed, aging is known to be associated with a low level of chronic inflammation—inflamm-aging. Given that the median age of cancer diagnosis is 66 years and that immunotherapeutic interventions such as cancer vaccines are currently given in combination with or after other forms of treatments which themselves have immune-modulating potential such as surgery, chemotherapy and radiotherapy, the choice of adjuvants requires careful consideration in order to achieve the maximum immune response in a compromised environment. In addition, more clinical trials need to be performed to carefully assess how less conventional form of immune adjuvants, such as exercise, diet and psychological care which have all be shown to influence immune responses can be incorporated to improve the efficacy of cancer vaccines. In this review, adjuvants will be discussed with respect to the above-mentioned important elements.

Enhancing the Efficacy of Tumor Vaccines Based on Immune Evasion Mechanisms

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

Exhausted CD8+T Cells in the Tumor Immune Microenvironment: New Pathways to Therapy

Tumor-specific CD8⁺T cells are exposed to persistent antigenic stimulation which induces a dysfunctional state called "exhaustion." Though functioning to limit damage caused by immune response, T cell exhaustion leads to attenuated effector function whereby cytotoxic CD8⁺T cells fail to control tumor progression in the late stage. This pathway is a dynamic process from activation to "progenitor exhaustion" through to "terminally exhaustion" with distinct properties. With the rapid development of immunotherapy via enhancing T cell function, new studies are dissecting the mechanisms and identifying specific biomarkers of dynamic differentiation during the process of exhaustion. Further, although immune checkpoint inhibitors (ICIs) have achieved great success in clinical practice, most patients still show limited efficacy to ICIs. The expansion and differentiation of progenitor exhausted T cells explained the success of ICIs while the depletion of the progenitor T cell pool and the transient effector function of terminally exhausted T cells accounted for the failure of immune monotherapy in the context of exorbitant tumor burden. Thus, combination strategies are urgent to be utilized based on the reduction of tumor burden or the expansion of the progenitor T cell pool. In this review, we aim to introduce the concept of homeostasis of the activated and exhausted status of CD8⁺T cells in the tumor immune microenvironment, and present recent findings on dynamic differentiation process during T cell exhaustion and the implications for combination strategies in immune therapy.

Single-cell RNA sequencing reveals cellular and molecular immune profile in a Pembrolizumab-responsive PD-L1-negative lung cancer patient

High expression of PD-L1 predicts PD-1/PD-L1 inhibitor benefit, meanwhile a few PD-L1-negative patients still benefit from these drugs. In this study, we aimed to explore the underlying cellular and molecular characteristics via single-cell sequencing. Before and after treatment with Pembrolizumab, peripheral blood mononuclear cells (PBMCs) were isolated via Ficoll gradient. Thereafter, single-cell RNA sequencing was performed, and clinical significance was validated with The Cancer Genome Atlas (TCGA) cohort. All 3423 cells of 16 clusters were classified into eight cell types, including NKG7+ T, NKG7+ NK, Naïve T, CDC1C+ dendritic cells, CD8+ T cells, B cells, macrophages and erythrocytes. Cell proportion, the clinical significance of differentially expressed genes and significant pathways of NKG7+ T, NKG7+ NK, Naïve T and CD8+ T cells were analyzed. Ubiquitin-mediated proteolysis/cell cycle/natural killer cell-mediated cytotoxicity were identified as PD-1 blockage-responsive pathways in NKG7+ NK cells. Apoptosis/Th1 and Th2 cell differentiation were proposed as Pembrolizumab-affected pathways in NKT cells. In gene level, ID2, PIK3CD, UQCR10, MATK, MZB1, IL7R and TRGC2 showed a significant correlation with PD-1 expression after TCGA dataset validation, which could possess potential as predictive markers for patients with PD-L1-negative lung squamous cell carcinoma who can benefit from Pembrolizumab.

Novel progresses of chimeric antigen receptor (CAR) T cell therapy in multiple myeloma

Multiple myeloma (MM) is a malignant proliferative disease of plasma cells, which leads to suppressed hematopoietic and osteolytic diseases. Despite the use of traditional chemotherapy, hematopoietic stem cell transplantation (HSCT) and targeted drugs, MM still cannot be completely cured. In recent years, chimeric antigen receptor (CAR) T cells have revolutionized immunotherapy and cancer treatment. The great success of CAR-T cells in leukemia and lymphoma has promoted its development in MM. The primary requisite for developing clinically effective CAR-T cells suitable for MM is to identify the appropriate targets. In early clinical trials, CAR-T cells targeting B-cell maturation antigen (BCMA) have shown significant anti-MM activity. Currently popular targets in clinical research and preclinical research include CD138, CD38, CS1, CD19, κ light chain, CD56, CD44v6, Lewis Y, NY-ESO-1, CD229, etc. Common toxicities such as cytokine release syndrome (CRS) and neurotoxicity also occur but controllable. MM cells are mainly localized in bone marrow, therefore, the bone marrow microenvironment has a significant effect on the therapeutic effect of CAR-T cells. Targeting both MM cells and the bone marrow microenvironment is currently the most promising treatment. In this review, we provide a comprehensive overview of CAR-T cell therapy in MM, as well as outline potential targets and methods that can overcome local immunosuppression and improve the efficacy of CAR-T cells.

CXCL9 secreted by tumor-associated dendritic cells up-regulates PD-L1 expression in bladder cancer cells by activating the CXCR3 signaling

Background

Tumor-associated dendritic cells (TADCs) can interact with tumor cells to suppress anti-tumor T cell immunity. However, there is no information on whether and how TADCs can modulate programmed death-ligand 1 (PD-L1) expression by cancer cells.

Methods

Human peripheral blood monocytes were induced for DCs and immature DCs were cultured alone, or co-cultured with bladder cancer T24 or control SV-HUC-1 cells, followed by stimulating with LPS for DC activation. The activation status of DCs was characterized by flow cytometry and allogenic T cell proliferation. The levels of chemokines in the supernatants of co-cultured DCs were measured by CBA-based flow cytometry. The impacts of CXCL9 on PD-L1, STAT3 and Akt expression and STAT3 and Akt phosphorylation in T24 cells were determined by flow cytometry and Western blot.

Results

Compared with the control DCs, TADCs exhibited immature phenotype and had significantly lower capacity to stimulate allogenic T cell proliferation, particularly in the presence of recombinant CXCL9. TADCs produced significantly higher levels of CXCL9, which enhanced PD-L1 expression in T24 cells. Pre-treatment with AMG487 abrogated the CXCL9-increased PD-L1 expression in T24 cells. Treatment with CXCL9 significantly enhanced STAT3 and Akt activation in T24 cells.

Conclusions

TADCs produced high levels of CXCL9 that increased PD-L1 expression in bladder cancer T24 cells by activating the CXCR3-related signaling. Our findings may shed new lights in understanding the regulatory roles of TADCs in inhibiting antitumor T cell responses and promoting tumor growth.

Lipid Metabolism and Tumor Antigen Presentation

Tumors always evade immune surveillance and block T cell activation in a poorly immunogenic and immunosuppressive environment. Cancer cells and immune cells exhibit metabolic reprogramming in the tumor microenvironment (TME), which intimately links immune cell function and edits tumor immunology. In addition to glucose metabolism, amino acid and lipid metabolism also provide the materials for biological processes crucial in cancer biology and pathology. Furthermore, lipid metabolism is synergistically or negatively involved in the interactions between tumors and the microenvironment and contributes to the regulation of immune cells. Antigen processing and presentation as the initiation of adaptive immune response play a critical role in antitumor immunity. Therefore, a relationship exists between antigen-presenting cells and lipid metabolism in TME. This chapter introduces the updated understandings of lipid metabolism of tumor antigen-presenting cells and describes new directions in the manipulation of immune responses for cancer treatment.

An Antigen-Delivery Protein Nanoparticle Combined with Anti-PD-1 Checkpoint Inhibitor Has Curative Efficacy in an Aggressive Melanoma Model

Immune checkpoint inhibition is a promising alternative treatment to standard chemotherapies; however, it fails to achieve long-term remission in a significant portion of patients. A previously developed protein nanoparticle-based platform (E2 nanoparticle) delivers cancer antigens to increase antigen-specific tumor responses. While prior work has focussed on prophylactic conditions, the objectives in this study are therapeutic. It is hypothesized that immune checkpoint inhibition, when augmented by antigen delivery using E2 nanoparticles containing CpG oligonucleotide 1826 (CpG) and a glycoprotein 100 (gp100) melanoma antigen epitope (CpG-gp-E2), would synergistically elicit antitumor responses. To identify a regimen primed for obtaining effective treatment results, immune benchmarks in the spleen and tumor are examined. Conditions that lead to significant immune activation, including increases in gp100-specific interferon gamma (IFN-𝜸), CD8 T cells in the spleen, tumor-infiltrating CD8 T cells, and survival time are identified. Based on the findings, the resulting combination of CpG-gp-E2 and anti-programmed cell death protein 1 (anti-PD-1) treatment in tumor-challenged mice yield significantly increased long-term survival; more than 50% of the mice treated with combination therapy were tumor-free, compared with 0% and ≈5% for CpG-gp-E2 and anti-PD-1 alone, respectively. Evidence of a durable antitumor response is also observed upon tumor rechallenge, pointing to long-lasting immune memory.

The Role of the Tumor Microenvironment in Developing Successful Therapeutic and Secondary Prophylactic Breast Cancer Vaccines

Breast cancer affects roughly one in eight women over their lifetime and is a leading cause of cancer-related death in women. While outcomes have improved in recent years, prognosis remains poor for patients who present with either disseminated disease or aggressive molecular subtypes. Cancer immunotherapy has revolutionized the treatment of several cancers, with therapeutic vaccines aiming to direct the cytotoxic immune program against tumor cells showing particular promise. However, these results have yet to translate to breast cancer, which remains largely refractory from such approaches. Recent evidence suggests that the breast tumor microenvironment (TME) is an important and long understudied barrier to the efficacy of therapeutic vaccines. Through an improved understanding of the complex and biologically diverse breast TME, it may be possible to advance new combination strategies to render breast carcinomas sensitive to the effects of therapeutic vaccines. Here, we discuss past and present efforts to advance therapeutic vaccines in the treatment of breast cancer, the molecular mechanisms through which the TME contributes to the failure of such approaches, as well as the potential means through which these can be overcome.

The Roles of CD8+ T Cell Subsets in Antitumor Immunity

Effector CD8⁺ T cells are typically thought to be a homogenous group of cytotoxic cells that produce interferon-(IFN) γ. However, recent findings have challenged this notion because multiple subsets of CD8⁺ T cells have been described, each with distinct effector functions and cytotoxic potential. These subsets, referred to as the Tc subsets, have also been detected in tumor microenvironments (TMEs), where they potentially influence the antitumor response and patient outcomes. In this review, we highlight the prevalence and roles of Tc subsets in the TME. We also discuss their therapeutic applications in the context of adoptive immunotherapy to treat cancer.

Immunotherapy in Prostate Cancer

Immunotherapy encompasses a wide range of therapies to engage the immune system to target malignancies. In recent years, immunotherapy has made a major impact on treatment of metastatic cancer and has altered standard of care for many tumor types. However, predicting and understanding responses across tumor types has been challenging. While some metastatic cancers have shown dramatic responses to immunotherapy, such as melanoma, lung cancer, and renal cell carcinoma, prostate cancer has generally failed to show a significant response. However, small series of prostate cancer patients have shown impressive responses to cellular and immunotherapy. This review summarizes the current data for immunotherapy’s use in prostate cancer, as well as how currently available data might help predict patient responses to immunotherapy. Specifically, we will review vaccine-based therapies, immune checkpoint inhibitors, and future directions that are actively being explored.

Peptide Vaccine Combined Adjuvants Modulate Anti-tumor Effects of Radiation in Glioblastoma Mouse Model

Glioblastoma, the most common aggressive cancer, has a poor prognosis. Among the current standard treatment strategies, radiation therapy is the most commonly recommended. However, it is often unsuccessful at completely eliminating the cancer from the brain. A combination of radiation with other treatment methods should therefore be considered. It has been reported that radiotherapy in combination with immunotherapy might show a synergistic effect; however, this still needs to be investigated. In the current study, a “branched multipeptide and peptide adjuvants [such as pan DR epitope (PADRE) and polyinosinic-polycytidylic acid—stabilized with polylysine and carboxymethylcellulose—(poly-ICLC)],” namely vaccine and anti-PD1, were used as components of immunotherapy to assist in the anti-tumor effects of radiotherapy against glioblastomas. With regard to experimental design, immunological characterization of GL261 cells was performed and the effects of radiation on this cell line were also evaluated. An intracranial GL261 mouse glioma model was established, and therapeutic effects were observed based on tumor size and survival time. The distribution of effector immune cells in the spleen, based on cytotoxic T lymphocyte (CTL) and natural killer (NK) cell function, was determined. The pro-inflammatory and anti-inflammatory cytokine production from re-stimulated splenocytes and single tumor cells were also evaluated. As GL261 cells demonstrated both immunological characteristics and radiation sensitivity, they were found to be promising candidates for testing this combination treatment. Combinatorial treatment with radiation, vaccine, and anti-PD1 prolonged mouse survival by delaying tumor growth. Although this combination treatment led to an increase in the functional activity of both CTLs and NK cells, as evidenced by the increased percentage of these cells in the spleen, there was a greater shift toward CTL rather than NK cell activity. Moreover, the released cytokines from re-stimulated splenocytes and single tumor cells also showed a shift toward the pro-inflammatory response. This study suggests that immunotherapy comprising a branched multipeptide plus PADRE, poly-ICLC, and anti-PD1 could potentially enhance the anti-tumor effects of radiotherapy in a glioblastoma mouse model.

Immunotherapy in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is considered an immunogenic tumor that arises in chronically inflamed livers due to underlying chronic liver disease caused by viral and non-viral pathogenesis. This inflammation leads to tumor development and is associated to higher tumor immunogenicity. For this reason immunotherapeutic approaches may be suitable therapeutic strategies for HCC. Indeed, several preclinical and clinical data support this hypothesis showing that immunotherapy and even more their combination may be a good alternative candidate for the treatment of HCC patients. However, considering that the liver plays a central role in host defense as well as in the maintenance of self-tolerance, it is characterized by a strong intrinsic immune suppressive microenvironment as well as by a high immune evasion, which may represent a major impediment for an effective immune response against tumor. Furthermore, the low expression of tumor antigens on liver cancer cells leads to a lower T-cell activation and tumor infiltration, resulting in a less efficient control of the tumor growth and, consequently, in a worse clinical outcome. For this reason, strategies should be developed to counteract the different factors in the HCC tumor microenvironment playing a major role in reducing the effects of immunotherapy.

The function and clinical application of extracellular vesicles in innate immune regulation

The innate immune system plays a crucial role in the host defense against viral and microbial infection. Exosomes constitute a subset of extracellular vesicles (EVs) that can be released by almost all cell types. Owing to their capacity to shield the payload from degradation and to evade recognition and subsequent removal by the immune system, exosomes efficiently transport functional components to recipient cells. Accumulating evidence has recently shown that exosomes derived from tumor cells, host cells and even bacteria and parasites mediate the communication between the invader and innate immune cells and thus play an irreplaceable function in the dissemination of pathogens and donor cell-derived molecules, modulating the innate immune responses of the host. In this review, we describe the current understanding of EVs (mainly focusing on exosomes) and summarize and discuss their crucial roles in determining innate immune responses. Additionally, we discuss the potential of using exosomes as biomarkers and cancer vaccines in diagnostic and therapeutic applications.

Tackling hepatocellular carcinoma with individual or combinatorial immunotherapy approaches

Hepatocellular carcinoma (HCC) is the third leading cause of death from cancer globally. Indeed, there is a single drug approved as first-line systemic therapy in advanced unresectable HCC, providing a very limited survival benefit. In earlier stages, 5-year survival rates after surgical and loco-regional therapies are extremely variable depending on the stage of disease. Nevertheless, HCC is considered an immunogenic tumor arising in chronically inflamed livers. In such a scenario, immunotherapy strategies for HCC, in particular combinations including cancer vaccines, may represent a key therapeutic tool to improve clinical outcome in HCC patients. However, a lot of improvement is needed given the disappointing results obtained so far.

Role of Tumor-Mediated Dendritic Cell Tolerization in Immune Evasion

The vast majority of cancer-related deaths are due to metastasis, a process that requires evasion of the host immune system. In addition, a significant percentage of cancer patients do not benefit from our current immunotherapy arsenal due to either primary or secondary immunotherapy resistance. Importantly, select subsets of dendritic cells (DCs) have been shown to be indispensable for generating responses to checkpoint inhibitor immunotherapy. These observations are consistent with the critical role of DCs in antigen cross-presentation and the generation of effective anti-tumor immunity. Therefore, the evolution of efficient tumor-extrinsic mechanisms to modulate DCs is expected to be a potent strategy to escape immunosurveillance and various immunotherapy strategies. Despite this critical role, little is known regarding the methods by which cancers subvert DC function. Herein, we focus on those select mechanisms utilized by developing cancers to co-opt and tolerize local DC populations. We discuss the reported mechanisms utilized by cancers to induce DC tolerization in the tumor microenvironment, describing various parallels between the evolution of these mechanisms and the process of mesenchymal transformation involved in tumorigenesis and metastasis, and we highlight strategies to reverse these mechanisms in order to enhance the efficacy of the currently available checkpoint inhibitor immunotherapies.

Evaluation of a ConvitVax/anti-PD-1 combined immunotherapy for breast cancer treatment

Breast cancer therapies using checkpoints alone have not been highly effective. Based on previous experiences using the ConvitVax, an autologous tumor cells/bacillus Calmette-Guérin (BCG)/formalin-based vaccine, in breast cancer and the potential success of combined therapies, we sought to ascertain whether the ConvitVax combined with anti-PD-1 enhances the antitumor effect in a 4T1 breast cancer model. Animals received four weekly injections of either PBS (G1), ConvitVax (200 μg cell homogenate, 0.0625 mg BCG, 0.02% formalin) (G2), 50 μg anti-PD-1 (G3), or ConvitVax plus anti-PD-1 (200 μg cell homogenate, 0.0625 mg BCG, 0.02% formalin, 50 μg anti-PD-1) (G4). Five weeks post tumor induction all mice were euthanized, tumors extracted and evaluated pathologically and by immunohistochemistry. The combination group (G4) showed 10% more tumor necrosis, greater infiltration of PD-1⁺ cells and lower infiltration of TAMs, evidencing that the combination of ConvitVax and anti-PD-1 can improve the antitumor effect of the vaccine. Using a higher anti-PD-1 dose and administering each treatment at different times could further potentiate the effect of our therapy. Given the vaccine’s low cost and simple preparation, its use in combination with checkpoints or other target-specific compounds may lead to a highly effective personalized breast cancer immunotherapy.

Safety and Efficacy of Therapeutic Cancer Vaccines Alone or in Combination With Immune Checkpoint Inhibitors in Cancer Treatment

Therapeutic cancer vaccines have proven to seldom induce dramatic clinical response when used alone, and therefore, they are being studied in combination with additional treatment modalities to achieve optimal treatment activities. Growing preclinical data show that combining vaccines and immune checkpoint inhibitors (ICIs) can prime intensified immunogenicity and modulate immunosuppressive tumor microenvironment. Herein, we focus on the safety and efficacy of approved and promising cancer vaccines alone or combined with ICIs in the treatment of several malignancies. Generally, the majority of clinical trials support the concept of synergy that combination therapy of vaccines and ICIs holds maximized potential to improve clinical outcomes. Importantly, the combination has acceptable safety and minimal additional toxicity compared with single-agent vaccines or ICIs. Additionally, the potential strategies of combining personalized tumor vaccines with ICIs will become priority option and future direction of vaccine development and application and the urgent need to develop effective biomarkers to screen appropriate patient populations and predict response to combination therapy.

PD-1 blockade in subprimed CD8 cells induces dysfunctional PD-1+CD38hi cells and anti-PD-1 resistance

Understanding resistance to antibody to programmed cell death protein 1 (PD-1; anti-PD-1) is crucial for the development of reversal strategies. In anti-PD-1-resistant models, simultaneous anti-PD-1 and vaccine therapy reversed resistance, while PD-1 blockade before antigen priming abolished therapeutic outcomes. This was due to induction of dysfunctional PD-1⁺CD38^hi CD8⁺ cells by PD-1 blockade in suboptimally primed CD8 cell conditions induced by tumors. This results in erroneous T cell receptor signaling and unresponsiveness to antigenic restimulation. On the other hand, PD-1 blockade of optimally primed CD8 cells prevented the induction of dysfunctional CD8 cells, reversing resistance. Depleting PD-1⁺CD38^hi CD8⁺ cells enhanced therapeutic outcomes. Furthermore, non-responding patients showed more PD-1⁺CD38⁺CD8⁺ cells in tumor and blood than responders. In conclusion, the status of CD8⁺ T cell priming is a major contributor to anti-PD-1 therapeutic resistance. PD-1 blockade in unprimed or suboptimally primed CD8 cells induces resistance through the induction of PD-1⁺CD38^hi CD8⁺ cells that is reversed by optimal priming. PD-1⁺CD38^hi CD8⁺ cells serve as a predictive and therapeutic biomarker for anti-PD-1 treatment. Sequencing of anti-PD-1 and vaccine is crucial for successful therapy.

Neoantigen vaccine: an emerging tumor immunotherapy

Genetic instability of tumor cells often leads to the occurrence of a large number of mutations, and expression of non-synonymous mutations can produce tumor-specific antigens called neoantigens. Neoantigens are highly immunogenic as they are not expressed in normal tissues. They can activate CD4+ and CD8+ T cells to generate immune response and have the potential to become new targets of tumor immunotherapy. The development of bioinformatics technology has accelerated the identification of neoantigens. The combination of different algorithms to identify and predict the affinity of neoantigens to major histocompatibility complexes (MHCs) or the immunogenicity of neoantigens is mainly based on the whole-exome sequencing technology. Tumor vaccines targeting neoantigens mainly include nucleic acid, dendritic cell (DC)-based, tumor cell, and synthetic long peptide (SLP) vaccines. The combination with immune checkpoint inhibition therapy or radiotherapy and chemotherapy might achieve better therapeutic effects. Currently, several clinical trials have demonstrated the safety and efficacy of these vaccines. Further development of sequencing technologies and bioinformatics algorithms, as well as an improvement in our understanding of the mechanisms underlying tumor development, will expand the application of neoantigen vaccines in the future.