TGFβ-derived immune modulatory vaccine: targeting the immunosuppressive and fibrotic tumor microenvironment in a murine model of pancreatic cancer

A Bifunctional Antibody Targeting PD-1 and TGF-β Signaling Has Antitumor Activity in Combination with Radiotherapy and Attenuates Radiation-Induced Lung Injury

Radio-immunotherapy has antitumor activity but also causes toxicity, which limits its clinical application. JS-201 is a dual antibody targeting PD-1 and TGF-β signaling. We investigated the antitumor effect of JS-201 combined with radiotherapy (RT) and the effect on radiation-induced lung injury (RILI). Different tumor models were established to detect the antitumor effects of the combination of JS-201 and RT, and RILI models were established to observe the effects of JS-201. Transcriptome sequencing showed that JS-201 optimized the tumor microenvironment by inhibiting extracellular matrix formation and angiogenesis. Combining JS-201 with RT further increased the inflammatory response and immune infiltration and showed great abscopal effects in Lewis lung cancer luciferase-positive models. Single-cell sequencing demonstrated that JS-201 reduced fibroblast proliferation by inhibiting the TGF-β/Smad pathway and the release of neutrophil extracellular traps mediated by ROS, thereby relieving radiation-induced pulmonary fibrosis. In conclusion, the JS-201 and RT combination enhances antitumor effects while mitigating acute and chronic RILI, and it may have potential for translational investigation as a cancer treatment strategy.

Targeting TGF-β: a promising strategy for cancer therapy

Transforming growth factor β (TGF-β) has important role in regulating the cellular processes including cell growth, differentiation, and migration. TGF-β exerts its effect by binding with transcellular membranes and kinases. Our findings demonstrate that TGF- β possess dual role as tumor suppressor and tumor promoter in different stages of cancer. TGF-β emerged as a promising anticancer agent that exhibits the apoptosis by acting on the suppressor of mothers against decapentaplegic (SMAD) and non-SMAD pathways. In this review we are focusing on the different types of TGF- β inhibitors active against skin cancer, breast cancer, colorectal cancer, lung cancer and ovarian cancer. TGF-β inhibitors includes ligand traps, monoclonal antibodies and receptor kinase inhibitors. In recent studies, TGF- β inhibitors have also been used in combination therapies in the treatment of cancer. The TGF-β has important role in vaccine therapy, Chemo and Radio Resistance in Cancer. TGF-β inhibitors present the novel therapeutic approach for the cancer therapy, highlighting the mechanism of action involved, clinical trials, challenges and exploring therapeutic opportunities. This will help to develop the novel TGF-β inhibitors as anticancer agents as well as help to resolve the problem of drug resistance by developing new drugs as anticancer agents.

Enhancing pancreatic cancer treatment: the role of H101 oncolytic virus in irreversible electroporation

Background

Irreversible Electroporation (IRE) offers a promising treatment for pancreatic cancer by using high-voltage pulses to kill tumor cells. But variations in tumor size and shape can lead to uneven electric fields, causing some cells to undergo only reversible electroporation (RE) and survive. However, RE can temporarily increase the permeability of the cell membrane, allowing small molecules to enter. H101 virus is an oncolytic adenovirus with deleted E1B-55kD and E3 regions that selectively targets and kills tumor cells. This study aimed to investigate whether the H101 oncolytic virus can serve as a supplementary therapeutic approach to kill tumors combined with RE.

Methods

We first explored how RE and the H101 oncolytic virus, both individually and together, affected tumor cell proliferation and migration in cellular experiments. Subsequent in vitro studies further assessed the effects of different treatments on tumor growth. To understand the mechanisms of pathway changes in tumors from different treatment groups, we analyzed tumor samples from each group using bulk RNA sequencing (bulk RNA-seq) and single-cell RNA sequencing (scRNA-seq). Additional biochemical techniques were used to validate key molecular changes.

Results

The combination of RE with the H101 oncolytic virus effectively inhibited pancreatic cancer cell proliferation and migration. Experiments using mouse subcutaneous tumor models confirmed that the combination therapy significantly reduced tumor growth. Further analysis bulk RNA-seq and scRNA-seq revealed that this combined approach activates the JNK-MAPK pathway, inducing apoptosis and enhancing therapeutic effects.

Conclusions

This combination boosts therapeutic effectiveness by activating the JNK-MAPK pathway and promoting tumor cell apoptosis. These findings suggest that the H101 oncolytic virus could serve as a valuable adjunct to improve the efficacy of IRE treatment.

4-1BB agonist targeted to fibroblast activation protein α synergizes with radiotherapy to treat murine breast tumor models

BACKGROUND

Ionizing radiation (IR) is a double-edged sword for immunotherapy as it may have both immunosuppressive and immunostimulatory effects. The biological effects of IR on the tumor microenvironment (TME) are a key factor for this balance. Fibroblast activation protein (FAP) is expressed on the surface of cancer-associated fibroblasts (CAF) in many cancer types and its abundance is associated with the poor immune response to immune-checkpoint-blockade in patients. We hypothesized that IR increases FAP expression in CAFs, therefore the combination of IR with targeted immunomodulators such as an agonistic anti-FAP-4-1BBL fusion protein could enhance the immune-mediated antitumoral effects of these treatments.

METHODS

The murine transplantable TS/A tumor-cell-line co-engrafted with CAFs was used to investigate increases in FAP expression in tumors following irradiation using immunohistochemistry, real-time polymerase chain reaction (RT-PCR) and multiplex tissue immunofluorescence. One lesion of bilateral tumor-bearing mice was only locally irradiated or combined with weekly injections of the bispecific muFAP-4-1BBL fusion protein (a mouse surrogate for RG7826). Tumor sizes were followed over time and TME was assessed by flow cytometry. Selective monoclonal antibody (mAb)-mediated depletions of immune cell populations, neutralizing interferon alpha/beta receptor 1 (IFNAR-I) IFNAR and interferon (IFN)-γ mAbs and gene-modified mice (4-1BB-/-) were used to delineate the immune cell subsets and mechanisms required for efficacy. 67Ga labeled muFAP-4-1BBL tracked by SPECT-CT was used to study biodistribution. In human colorectal carcinoma samples, the inducibility of FAP expression following radiotherapy was explored by multiplex immunofluorescence.

RESULTS

Irradiation of TS/A+CAF tumors in mice showed an increase in FAP levels after local irradiation. A suboptimal radiotherapy regimen in combination with muFAP-4-1BBL attained primary tumor control and measurable abscopal effects. Immune TME landscape analyses showed post-treatment increased infiltration of activated immune cells associated with the combined radioimmunotherapy treatment. Efficacy depended on CD8+ T cells, type I IFN, IFN-γ and ability to express 4-1BB. Biodistribution studies of muFAP-4-1BBL indicated enriched tumor targeting to irradiated tumors. Human colorectal cancer samples pre and post irradiation showed enhanced FAP expression after radiotherapy.

CONCLUSION

Increased FAP expression in the TME as a result of radiotherapy can be exploited to target agonist 4-1BB immunotherapy to malignant tumor lesions using an FAP-4-1BBL antibody fusion protein.

Enhancing the tissue penetration to improve sonodynamic immunotherapy for pancreatic ductal adenocarcinoma using membrane-camouflaged nanoplatform

PURPOSE

Sonodynamic therapy (SDT) is a promising strategy as an "in situ vaccine" to enhance activation of antitumor immune responses in solid tumors. However, the dense extracellular matrix (ECM) in pancreatic ductal adenocarcinoma (PDAC) lead to hypoxia and limited penetration of most drugs, aggravating the immunosuppressive tumor microenvironment and limiting the efficacy of synergistic sonodynamic immunotherapy. Therefore, it is essential to regulate ECM in order to alleviate tumor hypoxia and enhance the efficacy of sonodynamic immunotherapy for PDAC.

METHODS

The CPIM nanoplatform, consisting of a macrophage membrane-coated oxygen and drug delivery system (CM@PFOB-ICG-α-Mangostin), was synthesized using ultrasound and extrusion methods. The in vivo homologous targeting and hypoxia alleviation capabilities of CPIM were evaluated through near-infrared (NIR) imaging and photoacoustic (PA) imaging. The tumor growth inhibition potential and ability to reprogram the tumor microenvironment by the CPIM nanoplatform were also investigated.

RESULTS

Co-delivery of α-Mangostin inhibits CAFs and enhances stromal depletion, thereby facilitating better infiltration of macromolecules. Additionally, the nanoemulsion containing perfluorocarbon (PFC) can target tumor cells and accumulate within them through homologous targeting. The US irradiation results in the rapid release of oxygen, serving as a potential source of sonodynamic therapy for hypoxic tumors. Moreover, CPIM reshapes the immunosuppressive microenvironment increasing the population of cytotoxic T lymphocytes (CTLs), and enhancing their anti-tumor immune response through the use of anti-PDL1 antibodies to block immune checkpoints.

CONCLUSION

The present study offers a potential strategy for the co-delivery of oxygen and α-Mangostin, aiming to enhance the penetration of tumors to improve SDT. This approach effectively addresses the existing limitations of immune checkpoint blockade (ICB) treatment in solid tumors, while simultaneously boosting the immune response through synergistic sonodynamic immunotherapy.

Harnessing the tumor microenvironment: targeted cancer therapies through modulation of epithelial-mesenchymal transition

The tumor microenvironment (TME) is integral to cancer progression, impacting metastasis and treatment response. It consists of diverse cell types, extracellular matrix components, and signaling molecules that interact to promote tumor growth and therapeutic resistance. Elucidating the intricate interactions between cancer cells and the TME is crucial in understanding cancer progression and therapeutic challenges. A critical process induced by TME signaling is the epithelial-mesenchymal transition (EMT), wherein epithelial cells acquire mesenchymal traits, which enhance their motility and invasiveness and promote metastasis and cancer progression. By targeting various components of the TME, novel investigational strategies aim to disrupt the TME's contribution to the EMT, thereby improving treatment efficacy, addressing therapeutic resistance, and offering a nuanced approach to cancer therapy. This review scrutinizes the key players in the TME and the TME's contribution to the EMT, emphasizing avenues to therapeutically disrupt the interactions between the various TME components. Moreover, the article discusses the TME's implications for resistance mechanisms and highlights the current therapeutic strategies toward TME modulation along with potential caveats.

The antitumor activity of TGFβ-specific T cells is dependent on IL-6 signaling

Although interleukin (IL)-6 is considered immunosuppressive and tumor-promoting, emerging evidence suggests that it may support antitumor immunity. While combining immune checkpoint inhibitors (ICIs) and radiotherapy in patients with pancreatic cancer (PC) has yielded promising clinical results, the addition of an anti-IL-6 receptor (IL-6R) antibody has failed to elicit clinical benefits. Notably, a robust TGFβ-specific immune response at baseline in PC patients treated solely with ICIs and radiotherapy correlated with improved survival. Recent preclinical studies demonstrated the efficacy of a TGFβ-based immune modulatory vaccine in controlling PC tumor growth, underscoring the important role of TGFβ-specific immunity in PC. Here, we explored the importance of IL-6 for TGFβ-specific immunity in PC. In a murine model of PC, coadministration of the TGFβ-based immune modulatory vaccine with an anti-IL-6R antibody rendered the vaccine ineffective. IL-6R blockade hampered the development of vaccine-induced T-cells and tumoral T-cell infiltration. Furthermore, it impaired the myeloid population, resulting in increased tumor-associated macrophage infiltration and an enhanced immunosuppressive phenotype. In PC patients, in contrast to those receiving only ICIs and radiotherapy, robust TGFβ-specific T-cell responses at baseline did not correlate with improved survival in patients receiving ICIs, radiotherapy and IL-6R blockade. Peripheral blood immunophenotyping revealed that IL-6R blockade altered the T-cell and monocytic compartments, which was consistent with the findings in the murine model. Our data suggest that the antitumor efficacy of TGFβ-specific T cells in PC depends on the presence of IL-6 within the tumor. Consequently, caution should be exercised when employing IL-6R blockade in patients receiving cancer immunotherapy.

TGFB2 mRNA Levels Prognostically Interact with Interferon-Alpha Receptor Activation of IRF9 and IFI27, and an Immune Checkpoint LGALS9 to Impact Overall Survival in Pancreatic Ductal Adenocarcinoma

The treatment of pancreatic ductal adenocarcinoma (PDAC) is an unmet challenge, with the median overall survival rate remaining less than a year, even with the use of FOLFIRINOX-based therapies. This study analyzed archived macrophage-associated mRNA expression using datasets deposited in the UCSC Xena web platform to compare normal pancreatic tissue and PDAC tumor samples. The TGFB2 gene exhibited low mRNA expression levels in normal tissue, with less than one TPM. In contrast, in tumor tissue, TGFB2 expression levels exhibited a 7.9-fold increase in mRNA expression relative to normal tissue (p < 0.0001). Additionally, components of the type-I interferon signaling pathway exhibited significant upregulation of mRNA levels in tumor tissue, including Interferon alpha/beta receptor 1 (IFNAR1; 3.4-fold increase, p < 0.0001), Interferon regulatory factor 9 (IRF9; 4.2-fold increase, p < 0.0001), Signal transducer and activator of transcription 1 (STAT1; 7.1-fold increase, p < 0.0001), and Interferon Alpha Inducible Protein 27 (IFI27; 66.3-fold increase, p < 0.0001). We also utilized TCGA datasets deposited in cBioportal and KMplotter to relate mRNA expression levels to overall survival outcomes. These increased levels of mRNA expression were found to be prognostically significant, whereby patients with high expression levels of either TGFB2, IRF9, or IFI27 showed median OS times ranging from 16 to 20 months (p < 0.01 compared to 72 months for patients with low levels of expression for both TGFB2 and either IRF9 or IFI27). Examination of the KMplotter database determined the prognostic impact of TGFB2 mRNA expression levels by comparing patients expressing high versus low levels of TGFB2 (50th percentile cut-off) in low macrophage TME. In TME with low macrophage levels, patients with high levels of TGFB2 mRNA exhibited significantly shorter OS outcomes than patients with low TGFB2 mRNA levels (Median OS of 15.3 versus 72.7 months, p < 0.0001). Furthermore, multivariate Cox regression models were applied to control for age at diagnosis. Nine genes exhibited significant increases in hazard ratios for TGFB2 mRNA expression, marker gene mRNA expression, and a significant interaction term between TGFB2 and marker gene expression (mRNA for markers: C1QA, CD74, HLA-DQB1, HLA-DRB1, HLA-F, IFI27, IRF9, LGALS9, MARCO). The results of our study suggest that a combination of pharmacological tools can be used in treating PDAC patients, targeting both TGFB2 and the components of the type-I interferon signaling pathway. The significant statistical interaction between TGFB2 and the nine marker genes suggests that TGFB2 is a negative prognostic indicator at low levels of the IFN-I activated genes and TAM marker expression, including the immune checkpoint LGALS9 (upregulated 16.5-fold in tumor tissue; p < 0.0001).

Panoramic tumor microenvironment in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is notorious for its resistance to various treatment modalities. The genetic heterogeneity of PDAC, coupled with the presence of a desmoplastic stroma within the tumor microenvironment (TME), contributes to an unfavorable prognosis. The mechanisms and consequences of interactions among different cell types, along with spatial variations influencing cellular function, potentially play a role in the pathogenesis of PDAC. Understanding the diverse compositions of the TME and elucidating the functions of microscopic neighborhoods may contribute to understanding the immune microenvironment status in pancreatic cancer. As we delve into the spatial biology of the microscopic neighborhoods within the TME, aiding in deciphering the factors that orchestrate this intricate ecosystem. This overview delineates the fundamental constituents and the structural arrangement of the PDAC microenvironment, highlighting their impact on cancer cell biology.

Unveiling the contribution of tumor-associated macrophages in driving epithelial-mesenchymal transition: a review of mechanisms and therapeutic Strategies

Tumor-associated macrophages (TAMs), fundamental constituents of the tumor microenvironment (TME), significantly influence cancer development, primarily by promoting epithelial-mesenchymal transition (EMT). EMT endows cancer cells with increased motility, invasiveness, and resistance to therapies, marking a pivotal juncture in cancer progression. The review begins with a detailed exposition on the origins of TAMs and their functional heterogeneity, providing a foundational understanding of TAM characteristics. Next, it delves into the specific molecular mechanisms through which TAMs induce EMT, including cytokines, chemokines and stromal cross-talking. Following this, the review explores TAM-induced EMT features in select cancer types with notable EMT characteristics, highlighting recent insights and the impact of TAMs on cancer progression. Finally, the review concludes with a discussion of potential therapeutic targets and strategies aimed at mitigating TAM infiltration and disrupting the EMT signaling network, thereby underscoring the potential of emerging treatments to combat TAM-mediated EMT in cancer. This comprehensive analysis reaffirms the necessity for continued exploration into TAMs' regulatory roles within cancer biology to refine therapeutic approaches and improve patient outcomes.

Mechanism and role of nuclear laminin B1 in cell senescence and malignant tumors

Nuclear lamin B1 (LMNB1) is a member of the nuclear lamin protein family. LMNB1 can maintain and ensure the stability of nuclear structure and influence the process of cell senescence by regulating chromatin distribution, DNA replication and transcription, gene expression, cell cycle, etc. In recent years, several studies have shown that the abnormal expression of LMNB1, a classical biomarker of cell senescence, is highly correlated with the progression of various malignant tumors; LMNB1 is therefore considered a new potential tumor marker and therapeutic target. However, the mechanism of action of LMNB1 is influenced by many factors, which are difficult to clarify at present. This article focuses on the recent progress in understanding the role of LMNB1 in cell senescence and malignant tumors and offers insights that could contribute to elucidating the mechanism of action of LMNB1 to provide a new direction for further research.

State-Of-The-Art Advancements on Cancer Vaccines and Biomarkers

The origins of cancer vaccines date back to the 1800s. Since then, there have been significant efforts to generate vaccines against solid and hematologic malignancies using a variety of platforms. To date, these efforts have generally been met with minimal success. However, in the era of improved methods and technological advancements, supported by compelling preclinical and clinical data, a wave of renewed interest in the field offers the promise of discovering field-changing paradigms in the management of established and resected disease using cancer vaccines. These include novel approaches to personalized neoantigen vaccine development, as well as innovative immune-modulatory vaccines (IMVs) that facilitate activation of antiregulatory T cells to limit immunosuppression caused by regulatory immune cells. This article will introduce some of the limitations that have affected cancer vaccine development over the past several decades, followed by an introduction to the latest advancements in neoantigen vaccine and IMV therapy, and then conclude with a discussion of some of the newest technologies and progress that are occurring across the cancer vaccine space. Cancer vaccines are among the most promising frontiers for breakthrough innovations and strategies poised to make a measurable impact in the ongoing fight against cancer.

A novel TGFbeta/TGILR axis mediates crosstalk between cancer-associated fibroblasts and tumor cells to drive gastric cancer progression

Transforming growth factor beta (TGFβ) signaling plays a critical role in tumorigenesis and metastasis. However, little is known about the biological function of TGFbeta-induced lncRNA in cancer. In this study, we discovered a novel TGFbeta-induced lncRNA, termed TGILR, whose function in cancer remains unknown to date. TGILR expression was directly activated by the canonical TGFbeta/SMAD3 signaling axis, and this activation is highly conserved in cancer. Clinical analysis showed that TGILR overexpression showed a significant correlation with lymph node metastasis and poor survival and was an independent prognostic factor in gastric cancer (GC). Depletion of TGILR caused an obvious inhibitory effect on GC cell proliferation, invasion, and epithelial-mesenchymal transition (EMT) in vitro and in vivo. More importantly, we demonstrated that TGFbeta signaling in GC was overactivated due to cancer-associated fibroblast (CAF) infiltration. Mechanistically, increased level of CAF-secreted TGFbeta activates TGFbeta signaling, leading to TGILR overexpression in GC cells. Meanwhile, TGILR overexpression inhibited the microRNA biogenesis of miR-1306 and miR-33a by interacting with TARBP2 and reducing its protein stability, thereby promoting GC progression via TCF4-mediated EMT signaling. In conclusion, CAF infiltration drives GC metastasis and EMT signaling through activating TGFbeta/TGILR axis. Targeted blocking of CAF-derived TGFbeta should be a promising anticancer strategy in GC.

Progress in the development of vaccines for pancreatic adenocarcinoma

Pancreatic cancer, which is regarded as the third deadliest cancer globally, poses a significant challenge because of its limited range of treatment options and high mortality rate. Currently, there is a focus on both the development of a novel concept in vaccine designing and the parallel study of the associated immune mechanisms. To further our understanding of the healthcare field, a variety of promising designs have been introduced for in-depth study. The designs were developed to include the mKRAS-specific amphiphile vaccine, which targets a specific mutation in the KRAS gene in addition to the multi-antigen targeted DNA vaccine, which aims to stimulate an immune response against multiple cancer antigens. Furthermore, later designs of vaccines were introduced based on the development of peptide-based cancer vaccines, mRNA-based vaccines, cell-based vaccines, and engineered bacterial vectors using an oral Salmonella-based vaccine. The study presents the concept on which the new vaccine is based and discusses the up-to-date immunological manifestations of these designed vaccines.

Multifaceted TGF-β signaling, a master regulator: From bench-to-bedside, intricacies, and complexities

Physiological embryogenesis and adult tissue homeostasis are regulated by transforming growth factor-β (TGF-β), an evolutionarily conserved family of secreted polypeptide factors, acting in an autocrine and paracrine manner. The role of TGF-β in inflammation, fibrosis, and cancer is complex and sometimes even contradictory, exhibiting either inhibitory or promoting effects depending on the stage of the disease. Under pathological conditions, especially fibrosis and cancer, overexpressed TGF-β causes extracellular matrix deposition, epithelial-mesenchymal transition, cancer-associated fibroblast formation, and/or angiogenesis. In this review article, we have tried to dive deep into the mechanism of action of TGF-β in inflammation, fibrosis, and carcinogenesis. As TGF-β and its downstream signaling mechanism are implicated in fibrosis and carcinogenesis blocking this signaling mechanism appears to be a promising avenue. However, targeting TGF-β carries substantial risk as this pathway is implicated in multiple homeostatic processes and is also known to have tumor-suppressor functions. There is a need for careful dosing of TGF-β drugs for therapeutic use and patient selection.

Dissecting tumor microenvironment heterogeneity in syngeneic mouse models: insights on cancer-associated fibroblast phenotypes shaped by infiltrating T cells

Murine syngeneic tumor models have been used extensively for cancer research for several decades and have been instrumental in driving the discovery and development of cancer immunotherapies. These tumor models are very simplistic cancer models, but recent reports have, however, indicated that the different inoculated cancer cell lines can lead to the formation of unique tumor microenvironments (TMEs). To gain more knowledge from studies based on syngeneic tumor models, it is essential to obtain an in-depth understanding of the cellular and molecular composition of the TME in the different models. Additionally, other parameters that are important for cancer progression, such as collagen content and mechanical tissue stiffness across syngeneic tumor models have not previously been reported. Here, we compare the TME of tumors derived from six common syngeneic tumor models. Using flow cytometry and transcriptomic analyses, we show that strikingly unique TMEs are formed by the different cancer cell lines. The differences are reflected as changes in abundance and phenotype of myeloid, lymphoid, and stromal cells in the tumors. Gene expression analyses support the different cellular composition of the TMEs and indicate that distinct immunosuppressive mechanisms are employed depending on the tumor model. Cancer-associated fibroblasts (CAFs) also acquire very different phenotypes across the tumor models. These differences include differential expression of genes encoding extracellular matrix (ECM) proteins, matrix metalloproteinases (MMPs), and immunosuppressive factors. The gene expression profiles suggest that CAFs can contribute to the formation of an immunosuppressive TME, and flow cytometry analyses show increased PD-L1 expression by CAFs in the immunogenic tumor models, MC38 and CT26. Comparison with CAF subsets identified in other studies shows that CAFs are skewed towards specific subsets depending on the model. In athymic mice lacking tumor-infiltrating cytotoxic T cells, CAFs express lower levels of PD-L1 and lower levels of fibroblast activation markers. Our data underscores that CAFs can be involved in the formation of an immunosuppressive TME.

Novel strategies optimize immunotherapy by improving the cytotoxic function of T cells for pancreatic cancer treatment

Pancreatic cancer (PC) is considered highly malignant due to its unsatisfying prognosis and limited response to therapies. Immunotherapy has therefore been developed to harness the antigen-specific properties and cytotoxicity of the immune system, aiming to induce a robust anti-tumor immune response that specifically demolishes PC cells while minimizing lethality in healthy tissue. The activation and augmentation of cytotoxic T cells play a critical role in the initiation and final success of immunotherapy. PC, however, is often immunotherapy resistant due to its intrinsic immunosuppressive tumor microenvironment that consequently hampers effective T cell priming. Emerging therapeutic approaches are orientated to modulate the tumor microenvironment in PC to enhance immune system involvement and heighten T cell efficacy. These novel strategies have shown promising therapeutic effects in the treatment of PC either as standalone approaches or combinatorial with other therapeutic schemes. The objective of this article is to explore innovative approaches to optimize immunotherapy for PC patients through T cell cytotoxic function augmentation.

Recent Advances in Targeted Drug Delivery Strategy for Enhancing Oncotherapy

Targeted drug delivery is a precise and effective strategy in oncotherapy that can accurately deliver drugs to tumor cells or tissues to enhance their therapeutic effect and, meanwhile, weaken their undesirable side effects on normal cells or tissues. In this research field, a large number of researchers have achieved significant breakthroughs and advances in oncotherapy. Typically, nanocarriers as a promising drug delivery strategy can effectively deliver drugs to the tumor site through enhanced permeability and retention (EPR) effect-mediated passive targeting and various types of receptor-mediated active targeting, respectively. Herein, we review recent targeted drug delivery strategies and technologies for enhancing oncotherapy. In addition, we also review two mainstream drug delivery strategies, passive and active targeting, based on various nanocarriers for enhancing tumor therapy. Meanwhile, a comparison and combination of passive and active targeting are also carried out. Furthermore, we discuss the associated challenges of passive and active targeted drug delivery strategies and the prospects for further study.

Roles of differently polarized macrophages in the initiation and progressionof pancreatic cancer

During development of pancreatic cancer macrophage-mediated inflammatory processes and the formation of cancerous lesions are tightly connected. Based on insight from mouse models we provide an overview on the functions of classically-activated pro-inflammatory and alternatively-activated anti-inflammatory macrophages in the initiation and progression of pancreatic cancer. We highlight their roles in earliest events of tumor initiation such as acinar-to-ductal metaplasia (ADM), organization of the fibrotic lesion microenvironment, and growth of low-grade (LG) lesions. We then discuss their roles as tumor-associated macrophages (TAM) in progression to high-grade (HG) lesions with a cancerous invasive phenotype and an immunosuppressive microenvironment. Another focus is on how targeting these macrophage populations can affect immunosuppression, fibrosis and responses to chemotherapy, and eventually how this knowledge could be used for novel therapy approaches for patients with pancreatic ductal adenocarcinoma (PDA).

Molecular and metabolic regulation of immunosuppression in metastatic pancreatic ductal adenocarcinoma

Immunosuppression is a hallmark of pancreatic ductal adenocarcinoma (PDAC), contributing to early metastasis and poor patient survival. Compared to the localized tumors, current standard-of-care therapies have failed to improve the survival of patients with metastatic PDAC, that necessecitates exploration of novel therapeutic approaches. While immunotherapies such as immune checkpoint blockade (ICB) and therapeutic vaccines have emerged as promising treatment modalities in certain cancers, limited responses have been achieved in PDAC. Therefore, specific mechanisms regulating the poor response to immunotherapy must be explored. The immunosuppressive microenvironment driven by oncogenic mutations, tumor secretome, non-coding RNAs, and tumor microbiome persists throughout PDAC progression, allowing neoplastic cells to grow locally and metastasize distantly. The metastatic cells escaping the host immune surveillance are unique in molecular, immunological, and metabolic characteristics. Following chemokine and exosomal guidance, these cells metastasize to the organ-specific pre-metastatic niches (PMNs) constituted by local resident cells, stromal fibroblasts, and suppressive immune cells, such as the metastasis-associated macrophages, neutrophils, and myeloid-derived suppressor cells. The metastatic immune microenvironment differs from primary tumors in stromal and immune cell composition, functionality, and metabolism. Thus far, multiple molecular and metabolic pathways, distinct from primary tumors, have been identified that dampen immune effector functions, confounding the immunotherapy response in metastatic PDAC. This review describes major immunoregulatory pathways that contribute to the metastatic progression and limit immunotherapy outcomes in PDAC. Overall, we highlight the therapeutic vulnerabilities attributable to immunosuppressive factors and discuss whether targeting these molecular and immunological "hot spots" could improve the outcomes of PDAC immunotherapies.

Crosstalk between arginine, glutamine, and the branched chain amino acid metabolism in the tumor microenvironment

Arginine, glutamine, and the branched chain amino acids (BCAAs) are a focus of increased interest in the field of oncology due to their importance in the metabolic reprogramming of cancer cells. In the tumor microenvironment (TME), these amino acids serve to support the elevated biosynthetic and energy demands of cancer cells, while simultaneously maintaining the growth, homeostasis, and effector function of tumor-infiltrating immune cells. To escape immune destruction, cancer cells utilize a variety of mechanisms to suppress the cytotoxic activity of effector T cells, facilitating T cell exhaustion. One such mechanism is the ability of cancer cells to overexpress metabolic enzymes specializing in the catabolism of arginine, glutamine, and the BCAAs in the TME. The action of such enzymes supplies cancer cells with metabolic intermediates that feed into the TCA cycle, supporting energy generation, or providing precursors for purine, pyrimidine, and polyamine biosynthesis. Armed with substantial metabolic flexibility, cancer cells redirect amino acids from the TME for their own advantage and growth, while leaving the local infiltrating effector T cells deprived of essential nutrients. This review addresses the metabolic pressure that cancer cells exert over immune cells in the TME by up-regulating amino acid metabolism, while discussing opportunities for targeting amino acid metabolism for therapeutic intervention. Special emphasis is given to the crosstalk between arginine, glutamine, and BCAA metabolism in affording cancer cells with metabolic dominance in the TME.

The Tango between Cancer-Associated Fibroblasts (CAFs) and Immune Cells in Affecting Immunotherapy Efficacy in Pancreatic Cancer

The lack of response to therapy in pancreatic ductal adenocarcinoma (PDAC) patients has contributed to PDAC having one of the lowest survival rates of all cancer types. The poor survival of PDAC patients urges the exploration of novel treatment strategies. Immunotherapy has shown promising results in several other cancer types, but it is still ineffective in PDAC. What sets PDAC apart from other cancer types is its tumour microenvironment (TME) with desmoplasia and low immune infiltration and activity. The most abundant cell type in the TME, cancer-associated fibroblasts (CAFs), could be instrumental in why low immunotherapy responses are observed. CAF heterogeneity and interactions with components of the TME is an emerging field of research, where many paths are to be explored. Understanding CAF-immune cell interactions in the TME might pave the way to optimize immunotherapy efficacy for PDAC and related cancers with stromal abundance. In this review, we discuss recent discoveries on the functions and interactions of CAFs and how targeting CAFs might improve immunotherapy.

Pre-existing TGF-β-specific T-cell immunity in patients with pancreatic cancer predicts survival after checkpoint inhibitors combined with radiotherapy

BACKGROUND

Circulating transforming growth factor-β (TGF-β)-specific T cells that recognize TGF-β-expressing immune regulatory cells have been described in patients with cancer. TGF-β-derived peptide vaccination modulates the tumor microenvironment and has shown clinical effects in animal models of pancreatic cancer (PC). TGF-β-expressing regulatory cells are especially elevated in PC and may prevent the clinical response to immune checkpoint inhibitors (ICIs). Thus, in the present study we investigated the significance of TGF-β-specific T-cell immunity in patients with PC treated with ICI combined with radiotherapy in a randomized phase 2 study (CheckPAC).

METHODS

Immune responses to a TGF-β-derived epitope entitled TGF-β-15 as well as epitopes from Clostridium tetani (tetanus) and influenza were measured in peripheral blood mononuclear cells (PBMCs) with interferon-ɣ enzyme-linked immunospot assays. PBMCs were isolated before and after treatment. Correlations between immune response data and clinical data were evaluated with parametric and non-parametric statistical methods. Survival was analyzed with univariate and multivariate Cox-regression. TGF-β-15 specific T cells were isolated and expanded and examined for recognition of autologous regulatory immune cells by flow cytometry.

RESULTS

PBMCs from 32 patients were analyzed for immune responses to the TGF-β-derived epitope entitled TGF-β-15. Patients with a strong TGF-β-specific immune response at treatment initiation had longer progression-free and overall survival, compared with patients with a weak or no TGF-β-specific immune response. This remained significant in multivariate analysis. Patients with weak and strong TGF-β-specific responses displayed similar responses towards viral antigens. Furthermore, we show that TGF-β-specific T cells from a clinical responder specifically reacted to and lysed autologous, regulatory immune cells. Finally, mimicking a TGF-β-15 vaccination, we showed that repeated stimulations with the TGF-β-15 epitope in vitro enhanced the immune response to TGF-β-15.

CONCLUSION

A strong TGF-β-15 specific immune response was associated with clinical benefit and improved survival after ICI/radiotherapy for patients with PC. Importantly, the lack of TGF-β-specific T cells in some patients was not caused by a general immune dysfunction. TGF-β-specific T cells recognized regulatory immune cells and could be introduced in vitro in patients without spontaneous responses. Taken together, our data suggest that combining TGF-β-based vaccination with ICI/radiotherapy will be beneficial for patients with PC.