Restoring tumor immunogenicity with dendritic cell reprogramming

A new era in melanoma immunotherapy: focus on DCs metabolic reprogramming

Melanoma, being one of the most dangerous forms of skin cancer, is characterized by its aggressive and metastatic nature, with the potential to develop resistance to various treatments. This resistance makes the disease challenging to treat, emphasizing the need for new treatment strategies. Within the tumor microenvironment (TME), melanoma cells exploit metabolic shifts, particularly glycolysis, to create an immunosuppressive TME that prevents dendritic cells (DCs) from functioning properly. Essential metabolic alterations such as lactate and lipid accumulation, and lack of tryptophan disrupt DC maturation, antigen presentation, and T cell activation. In recent years, melanoma immunotherapy has increasingly focused on reprogramming the metabolism of DCs. This review paper aims to provide insights into the metabolic suppression of melanoma-associated DCs, allowing the design of therapeutic strategies based on metabolic interventions to promote or restore DC function. This contribution reviews the metabolic reprogramming of DCs as a new approach for melanoma immunotherapy.

Single-cell transcriptomics reveals immunosuppressive microenvironment and highlights tumor-promoting macrophage cells in Glioblastoma

Glioblastoma (GBM) is the most prevalent and aggressive primary brain malignancy in adults. Nevertheless, the cellular heterogeneity and complexity within the GBM microenvironment (TME) are still not fully understood, posing a significant obstacle in the advancement of more efficient immunotherapies for GBM. In this study, we conducted an integrated analysis of 48 tumor fragments from 24 GBM patients at the single-cell level, uncovering substantial molecular diversity within immune infiltrates. We characterized molecular signatures for five distinct tumor-associated macrophages (TAMs) subtypes. Notably, the TAM_MRC1 subtype displayed a pronounced M2 polarization signature. Additionally, we identified a subtype of natural killer (NK) cells, designated CD56dim_DNAJB1. This subtype is characterized by an exhausted phenotype, evidenced by an elevated stress signature and enrichment in the PD-L1/PD-1 checkpoint pathway. Our findings also highlight significant cell-cell interactions among malignant glioma cells, TAM, and NK cells within the TME. Overall, this research sheds light on the functional heterogeneity of glioma and immune cells in the TME, providing potential targets for therapeutic intervention in this immunologically cold cancer.

Cross-priming in cancer immunology and immunotherapy

Cytotoxic T cell immune responses against cancer crucially depend on the ability of a subtype of professional antigen-presenting cells termed conventional type 1 dendritic cells (cDC1s) to cross-present antigens. Cross-presentation comprises redirection of exogenous antigens taken from other cells to the major histocompatibility complex class I antigen-presenting machinery. In addition, once activated and having sensed viral moieties or T helper cell cooperation via CD40-CD40L interactions, cDC1s provide key co-stimulatory ligands and cytokines to mount and sustain CD8+ T cell immune responses. This regulated process of cognate T cell activation is termed cross-priming. In cancer mouse models, CD8+ T cell cross-priming by cDC1s is crucial for the efficacy of most, if not all, immunotherapy strategies. In patients with cancer, the presence and abundance of cDC1s in the tumour microenvironment is markedly associated with the level of T cell infiltration and responsiveness to immune checkpoint inhibitors. Therapeutic strategies to increase the numbers of cDC1s using FMS-like tyrosine kinase 3 ligand (FLT3L) and/or their activation status show evidence of efficacy in cancer mouse models and are currently being tested in initial clinical trials with promising results so far.

Recent developments in myeloid immune modulation in cancer therapy

Myeloid cells play a crucial dual role in cancer progression and response to therapy, promoting tumor growth, enabling immune suppression, and contributing to metastatic spread. The ability of these cells to modulate the immune system has made them attractive targets for therapeutic strategies aimed at shifting their function from tumor promotion to fostering antitumor immunity. Therapeutic approaches targeting myeloid cells focus on modifying their numbers, genetics, metabolism, and interactions within the tumor microenvironment. These strategies aim to reverse their suppressive functions and redirect them to support antitumor immune responses by inhibiting immunosuppressive pathways, targeting specific receptors, and promoting their differentiation into less immunosuppressive phenotypes. Here, we discuss recent approaches to clinically target tumor myeloid cells, focusing on reprogramming myeloid cells to promote antitumor immunity.

Modulation of the tumor immune microenvironment by Interferon Regulatory Factor 8 enhances immunotherapy in lung adenocarcinoma

Interferon regulatory factors (IRFs) are integral in governing the expression of Type I interferon (IFN) genes. However, the precise role of IRFs in lung adenocarcinoma remains elusive. Our objective is to elucidate the prognostic implications of IRFs and their potential influence on the immunotherapeutic response in patients with lung adenocarcinoma (LUAD). The association between IRFs expression and clinical as well as prognostic features was evaluated utilizing the TCGA database. Prognostic determinants for LUAD were pinpointed via univariate and multivariate analyses. Nomogram to evaluate prognosis predicated on IRF expression levels. Gene enrichments were conducted to elucidate the mechanisms of action. The degree of immune infiltration was using bioinformatics methods and was validated through a single-cell dataset. We compiled our unique cohort of LUAD patients who underwent anti-PD-1 therapy for subsequent immunohistochemistry and multicolor immunofluorescence staining to gauge the conclusion above. Our findings revealed that IRF8 serves as an independent risk factor for overall survival (OS) in patients with LUAD. An analysis of patients undergoing immunotherapy revealed a positive association between the expression of IRF8 and the response to the treatment. In our specific cohort treated with anti-PD-1, high IRF8 expression was observed to enhance immunotherapy response and prolong OS by modulating immune cell infiltration. Our retrospective analysis suggests that elevated IRF8 expression correlates with improved prognosis in LUAD, with higher IRF8 expression being predictive of a more robust immunotherapy response. Mechanistically, IRF8 expression is associated with a modulated tumor immune microenvironment and improved immunotherapeutic response.

Applications of mRNA Delivery in Cancer Immunotherapy

Cancer treatment is continually advancing, with immunotherapy gaining prominence as a standard modality that has markedly improved the management of various malignancies. Despite these advancements, the efficacy of immunotherapy remains variable, with certain cancers exhibiting limited response and patient outcomes differing considerably. Thus, enhancing the effectiveness of immunotherapy is imperative. A promising avenue is mRNA delivery, employing carriers such as liposomes, peptide nanoparticles, inorganic nanoparticles, and exosomes to introduce mRNA cargos encoding tumor antigens, immune-stimulatory, or immune-modulatory molecules into the tumor immune microenvironment (TIME). This method aims to activate the immune system to target and eradicate tumor cells. In this review, we introduce the characteristics and limitations of these carriers and summarize the application and mechanisms of currently prevalent cargos in mRNA-based tumor treatment. Additionally, given the significant clinical application of immune checkpoint inhibitors (ICIs) and chimeric antigen receptor (CAR)-based cell therapies in solid tumors (including melanoma, non-small-cell lung cancer, head and neck squamous cell carcinoma, triple-negative breast cancer, gastric cancer) and leukemia, which have become first-line treatments, we highlight and discuss recent progress in combining mRNA delivery with ICIs, CAR-T, CAR-NK, and CAR-macrophage therapies. This combination enhances the targeting capabilities and efficacy of ICIs and CAR-cell-based therapies, while also mitigating the long-term off-target toxicities associated with conventional methods. Finally, we analyze the limitations of current mRNA delivery systems, such as nuclease-induced mRNA instability, immunogenicity risks, complex carrier production, and knowledge gaps concerning dosing and safety. Addressing these challenges is crucial for unlocking the potential of mRNA in cancer immunotherapy. Overall, exploring mRNA delivery enriches our comprehension of cancer immunotherapy and holds promise for developing personalized and effective treatment strategies, potentially enhancing the immune responses of cancer patients and extending their survival time.

Cryo-Shocked Tumor-Reprogrammed Sonosensitive Antigen-Presenting Cells Improving Sonoimmunotherapy via T Cells and NK Cells Immunity

Ultrasound therapy has turned up as a noninvasive multifunctional tool for cancer immunotherapy. However, the insufficient co-stimulating molecules and loss of peptide-major histocompatibility complex I (MHC-I) expression on tumor cells lead to poor therapy of sonoimmunotherapies. Herein, this work develops a sonosensitive system to augment MHC-I unrestricted natural killer (NK) cell-mediated innate immunity and T cell-mediated adaptive immunity by leveraging antigen presentation cell (APC)-like tumor cells. Genetically engineered tumor cells featuring sufficient co-stimulating molecules are cryo-shocked and conjugated with a sonosensitizer, hematoporphyrin monomethyl ether, using click chemistry. These cells (DPNLs) exhibit characteristics of tumor and draining lymph node homing. Under ultrasound, NK cell-mediated innate immunity within the tumor microenvironment could be activated, and T cells in the tumor-draining lymph nodes (TDLNs) are stimulated through co-stimulatory molecules. In combination with programmed cell death ligand 1 (PD-L1) antibody, DPNLs extend the survival time and inhibited lung metastasis in triple-negative breast cancer (TNBC) models. This study provides an alternative approach for sonoimmunotherapy with precise sonosensitizer delivery and enhanced NK cell and T cell activation.

Exploring the immuno-nano nexus: A paradigm shift in tumor vaccines

Tumor vaccines have become a crucial strategy in cancer immunotherapy. Challenges of traditional tumor vaccines include inadequate immune activation and low efficacy of antigen delivery. Nanoparticles, with their tunable properties and versatile functionalities, have redefined the landscape of tumor vaccine design. In this review, we outline the multifaceted roles of nanoparticles in tumor vaccines, ranging from their capacity as delivery vehicles to their function as immunomodulatory adjuvants capable of stimulating anti-tumor immunity. We discuss how this innovative approach significantly boosts antigen presentation by leveraging tailored nanoparticles that facilitate efficient uptake by antigen-presenting cells. These nanoparticles have been meticulously designed to overcome biological barriers, ensuring optimal delivery to lymph nodes and effective interaction with the immune system. Overall, this review highlights the transformative power of nanotechnology in redefining the principles of tumor vaccines. The intent is to inform more efficacious and precise cancer immunotherapies. The integration of these advanced nanotechnological strategies should unlock new frontiers in tumor vaccine development, enhancing their potential to elicit robust and durable anti-tumor immunity.

Highlighting recent achievements to advance more effective cancer immunotherapy

From 17 to 19th October 2024, the XXI Italian Network for Bio-Immunotherapy of Tumors Meeting (NIBIT) took place in Palermo, in the marvelous historical location of Teatro Politeama, under the auspices of the Italian Association of Medical Oncology (AIOM), Italian Association of Cancer Research (AIRC), Fondazione Pezcoller, Italian Alliance against Cancer (ACC), Italian Lymphoma Foundation (FIL), Grazia Focacci Foundation and Melagioco Foundation. The conference covered a spectrum of topics ranging from target discovery to therapeutic advances in immuno-oncology, bringing world-renowned experts to present groundbreaking innovations in basic, translational, and clinical cancer research. Six sessions focused on cellular therapies, digital pathology, vaccines, tertiary lymphoid structures, and microenvironment in order to get deep insights on how to personalize diagnosis and therapies in the clinical setting. Young investigators had the opportunity to meet and greet their mentors, promoting the synergy of the academic and industrial sectors within the national and international panorama, discussing the application of artificial intelligence on multi-specific antibodies, drug conjugates, and antibody fusion proteins that are advancing the efficacy of precision medicine and minimizing off-target effects.

One-Pot Synthesis of Oxygen Vacancy-Rich Amorphous/Crystalline Heterophase CaWO4 Nanoparticles for Enhanced Radiodynamic-Immunotherapy

Radiodynamic therapy that employs X-rays to trigger localized reactive oxygen species (ROS) generation can tackle the tissue penetration issue of phototherapy. Although calcium tungstate (CaWO4) shows great potential as a radiodynamic agent benefiting from its strong X-ray absorption and the ability to generate electron-hole (e--h+) pairs, slow charge carrier transfer and fast e--h+ recombination greatly limit its ROS-generating performance. Herein, via a one-pot wet-chemical method, oxygen vacancy-rich amorphous/crystalline heterophase CaWO4 nanoparticles (Ov-a/c-CaWO4 NPs) with enhanced radiodynamic effect are synthesized for radiodynamic-immunotherapy of cancer. The phase composition and oxygen vacancy content of CaWO4 can be easily tuned by adjusting the solvothermal temperature. More intriguingly, the amorphous/crystalline interfaces and abundant oxygen vacancies accelerate charge carrier transfer and suppress e--h+ recombination, respectively, enabling synergistically improved ROS production from X-ray-irradiated Ov-a/c-CaWO4 NPs. In addition to directly inducing oxidative damage of cancer cells, radiodynamic generation of ROS also boosts immunogenic cell death to provoke a systemic antitumor immune response, thereby allowing the inhibition of both primary and distant tumors as well as cancer metastasis. This study establishes a synergistic enhancement strategy involving the integration of phase and defect engineering to improve the ROS generation capacity of radiodynamic-immunotherapeutic anticancer nanoagents.

Transcription factor-mediated reprogramming to antigen-presenting cells

Antigen-presenting cells (APCs) are a heterogenous group of immune cells composed by dendritic cells (DCs) and macrophages (Mϕ), which are critical for orchestrating immunity against cancer or infections. Several strategies have been explored to generate APC subsets, including enrichment from peripheral blood and differentiation from pluripotent or multipotent cells. During development, the generation of APC subsets is instructed by transcription factors (TFs). Direct cell reprogramming, also known as transdifferentiation, offers an approach to harness combinations of TFs to generate APCs from unrelated somatic cells, including cancer cells. In this review, we summarize the transcriptional specification of DC subsets, highlight transcriptional networks for their generation, and discuss future applications of DC reprogramming in cancer immunotherapy.

Recent advancement in the spatial immuno-oncology

Recent advancements in spatial transcriptomics and spatial proteomics enabled the high-throughput profiling of single or multi-cell types and cell states with spatial information. They transformed our understanding of the higher-order architectures and paired cell-cell interactions within a tumor microenvironment (TME). Within less than a decade, this rapidly emerging field has discovered much crucial fundamental knowledge and significantly improved clinical diagnosis in the field of immuno-oncology. This review summarizes the conceptual frameworks to understand spatial omics data and highlights the updated knowledge of spatial immuno-oncology.

Promising Cellular Immunotherapy for Colorectal Cancer Using Classical Dendritic Cells and Natural Killer T Cells

Colorectal cancer (CRC) remains one of the leading causes of cancer-related morbidity and mortality around the world. Despite advances in surgery, chemotherapy, and targeted therapies, the prognosis for patients with metastatic or advanced CRC remains poor. Immunotherapies comprising immune checkpoint inhibitors showed disappointing responses in metastatic CRC (mCRC). However, cellular immunotherapy, specifically using classical dendritic cells (cDCs), may hold unique promise in immune recognition for CRC antigens. cDCs are substantial players in immune recognition and are instrumental in orchestrating innate and adaptive immune responses by processing and presenting tumor antigens to effector cells. Natural killer T (NKT) cells are insufficiently studied but unique effector cells because of their ability to bridge innate and adaptive immune reactions and the crosstalk with dendritic cells in cancer. This review explores the therapeutic potential of using both cDCs and NKT cells as a synergistic therapy in CRC, focusing on their biological roles, strategies for harnessing their capabilities, clinical applications, and the challenges within the tumor microenvironment. Both cDCs and NKT cells can be used as a new effective approach for cell-based therapies in cancers to provide a new hope for CRC patients that are challenging to treat.

Interferon regulatory factor 8-driven reprogramming of the immune microenvironment enhances antitumor adaptive immunity and reduces immunosuppression in murine glioblastoma

BACKGROUND

Glioblastoma (GBM) has a highly immunosuppressive tumor immune microenvironment (TIME), largely mediated by myeloid-derived suppressor cells (MDSCs). Here, we utilized a retroviral replicating vector (RRV) to deliver Interferon Regulatory Factor 8 (IRF8), a master regulator of type 1 conventional dendritic cell (cDC1) development, in a syngeneic murine GBM model. We hypothesized that RRV-mediated delivery of IRF8 could "reprogram" intratumoral MDSCs into antigen-presenting cells and thereby restore T-cell responses.

METHODS

Effects of RRV-IRF8 on survival and tumor growth kinetics were examined in the SB28 murine GBM model. The immunophenotype was analyzed by flow cytometry and gene expression assays. We assayed functional immunosuppression and antigen presentation by ex vivo T-cell-myeloid co-culture.

RESULTS

Intratumoral injection of RRV-IRF8 in mice bearing intracerebral SB28 glioma significantly suppressed tumor growth and prolonged survival. RRV-IRF8 treated tumors exhibited significant enrichment of cDC1s and CD8+ T-cells. Additionally, myeloid cells derived from RRV-IRF8 tumors showed decreased expression of the immunosuppressive markers Arg1 and IDO1 and demonstrated reduced suppression of naïve T-cell proliferation in ex vivo co-culture, compared to controls. Furthermore, DCs from RRV-IRF8 tumors showed increased antigen presentation compared to those from control tumors. In vivo treatment with azidothymidine (AZT), a viral replication inhibitor, showed that IRF8 transduction in both tumor and non-tumor cells is necessary for survival benefit, associated with a reprogrammed, cDC1- and CD8 T-cell-enriched TIME.

CONCLUSIONS

Our results indicate that reprogramming of glioma-infiltrating myeloid cells by in vivo expression of IRF8 may reduce immunosuppression and enhance antigen presentation, achieving improved tumor control.

Enhancing tumor immunity via in vivo cDC1 reprogramming

A recent study by Ascic et al. demonstrates that in situ reprogramming of tumor cells into conventional dendritic cell (cDC)-like cells using viral-PIB transcription factors creates an immunogenic tumor microenvironment with T cell recruitment and activation. The study highlights the potential of tumor-specific cancer immunotherapy using in vivo reprogrammed cDCs.

Better, Faster, Stronger: Accelerating mRNA-Based Immunotherapies With Nanocarriers

Messenger ribonucleic acid (mRNA) therapeutics are attracting attention as promising tools in cancer immunotherapy due to their ability to leverage the in vivo expression of all known protein sequences. Even small amounts of mRNA can have a powerful effect on cancer vaccines by promoting the synthesis of tumor-specific antigens (TSA) or tumor-associated antigens (TAA) by antigen-presenting cells (APC). These antigens are then presented to T cells, eliciting strong antitumor immune stimulation. The potential of mRNA can be further enhanced by expressing immunomodulatory agents, such as cytokines, antibodies, and chimeric antigen receptors (CAR), enhancing tumor immunity. Recent research also explores mRNA-encoded tumor death inducers or tumor microenvironment (TME) modulators. Despite its promise, the clinical translation of mRNA-based anticancer strategies faces challenges, including inefficient targeted delivery in vivo, failure of endosomal escape, and inadequate intracellular mRNA release, resulting in poor transfection efficiencies. Inspired by the approval of lipid nanoparticle-loaded mRNA vaccines against coronavirus disease 2019 (COVID-19) and the encouraging outcomes of mRNA-based cancer therapies in trials, innovative nonviral nanotechnology delivery systems have been engineered. These aim to advance mRNA-based cancer immunotherapies from research to clinical application. This review summarizes recent preclinical and clinical progress in lipid and polymeric nanomedicines for delivering mRNA-encoded antitumor therapeutics, including cytokines and antibody-based immunotherapies, cancer vaccines, and CAR therapies. It also addresses advanced delivery systems for direct oncolysis or TME reprogramming and highlights key challenges in translating these therapies to clinical use, exploring future perspectives, including the role of artificial intelligence and machine learning in their development.

In vitro induction of anti‑lung cancer immune response by the A549 lung cancer stem cell lysate‑sensitized dendritic cell vaccine

Lung adenocarcinoma is one of the most fatal types of cancer worldwide, with non-small cell lung cancer being the most common subtype. Therefore, there is need for improved treatment approaches. Tumor growth results from the proliferation of a very small number of tumor stem cells, giving rise to the theory of cancer stem cells (CSCs). Lung CSCs are associated with lung cancer development, and although chemotherapy drugs can inhibit the proliferation of lung cancer cells, they have difficulty acting on lung CSCs. Even if the tumor appears to have disappeared after chemotherapy, the presence of a small number of residual tumor stem cells can lead to cancer recurrence and metastasis. Hence, targeting and eliminating lung CSCs is of significant therapeutic importance. In this study, we cultured A549 cells in sphere-forming conditions using B27, EGF, and bFGF, isolated peripheral blood mononuclear cells (PBMCs), and induced and characterized dendritic cells (DCs). We also isolated and expanded T lymphocytes. DC vaccines were prepared using A549 stem cell lysate or A549 cell lysate for sensitization and compared with non-sensitized DC vaccines. The content of IFN-γ in the supernatant of cultures with vaccines and T cells was measured by ELISA. The cytotoxic effects of the vaccines on A549 cells and stem cells were assessed using the Cytotox96 assay, and the impact of the vaccines on A549 cell migration and apoptosis was evaluated using Transwell assays and flow cytometry. DC vaccines sensitized with human lung CSC lysates induced significant in vitro cytotoxic effects on A549 lung cancer cells and CSCs by T lymphocytes, while not producing immune cytotoxic effects on human airway epithelial cells. Moreover, the immune-killing effect induced by DC vaccines sensitized with lung CSC lysates was superior to that of DC vaccines sensitized with lung cancer cells.

Reprogramming tumor cells to fight cancer

Cancer cells reprogrammed into dendritic cells in vivo promote antitumor immunity.

In vivo dendritic cell reprogramming for cancer immunotherapy

Immunotherapy can lead to long-term survival for some cancer patients, yet generalized success has been hampered by insufficient antigen presentation and exclusion of immunogenic cells from the tumor microenvironment. Here, we developed an approach to reprogram tumor cells in vivo by adenoviral delivery of the transcription factors PU.1, IRF8, and BATF3, which enabled them to present antigens as type 1 conventional dendritic cells. Reprogrammed tumor cells remodeled their tumor microenvironment, recruited, and expanded polyclonal cytotoxic T cells; induced tumor regressions; and established long-term systemic immunity in multiple mouse melanoma models. In human tumor spheroids and xenografts, reprogramming to immunogenic dendritic-like cells progressed independently of immunosuppression, which usually limits immunotherapy. Our study paves the way for human clinical trials of in vivo immune cell reprogramming for cancer immunotherapy.

Machine Learning-Directed Conversion of Glioblastoma Cells to Dendritic Cell-Like Antigen-Presenting Cells as Cancer Immunotherapy

Immunotherapy has limited efficacy in glioblastoma (GBM) due to the blood-brain barrier and the immunosuppressed or "cold" tumor microenvironment (TME) of GBM, which is dominated by immune-inhibitory cells and depleted of CTL and dendritic cells (DC). Here, we report the development and application of a machine learning precision method to identify cell fate determinants (CFD) that specifically reprogram GBM cells into induced antigen-presenting cells with DC-like functions (iDC-APC). In murine GBM models, iDC-APCs acquired DC-like morphology, regulatory gene expression profile, and functions comparable to natural DCs. Among these acquired functions were phagocytosis, direct presentation of endogenous antigens, and cross-presentation of exogenous antigens. The latter endowed the iDC-APCs with the ability to prime naïve CD8+ CTLs, a hallmark DC function critical for antitumor immunity. Intratumor iDC-APCs reduced tumor growth and improved survival only in immunocompetent animals, which coincided with extensive infiltration of CD4+ T cells and activated CD8+ CTLs in the TME. The reactivated TME synergized with an intratumor soluble PD1 decoy immunotherapy and a DC-based GBM vaccine, resulting in robust killing of highly resistant GBM cells by tumor-specific CD8+ CTLs and significantly extended survival. Lastly, we defined a unique CFD combination specifically for the human GBM to iDC-APC conversion of both glioma stem-like cells and non-stem-like cell GBM cells, confirming the clinical utility of a computationally directed, tumor-specific conversion immunotherapy for GBM and potentially other solid tumors.

A New Frontier in Tumor Eradication: Harnessing In Vivo Cellular Reprogramming for Durable Cancer Immunotherapy

Tumors evade immune detection by downregulating antigen presentation and hindering immune responses. Type 1 conventional dendritic cells (cDC1s) are vital in stimulating cytotoxic T cells against tumors. Ascic et al. are now demonstrating the in situ ability of PU.1, IRF8, and BATF3 (PIB) transcription factors to directly reprogram a plethora of tumors bypassing the suppressive effects of the tumor microenvironment, and leading to overall tumor regression while eliciting a systemic immune response that can protect from secondary tumor induction.

Bi-functional CpG-STAT3 decoy oligonucleotide triggers multilineage differentiation of acute myeloid leukemia in mice

Acute myeloid leukemia (AML) cells resist differentiation stimuli despite high expression of innate immune receptors, such as Toll-like receptor 9 (TLR9). We previously demonstrated that targeting Signal Transducer and Activator of Transcription 3 (STAT3) using TLR9-targeted decoy oligodeoxynucleotide (CpG-STAT3d) increases immunogenicity of human and mouse AML cells. Here, we elucidated molecular mechanisms of inv(16) AML reprogramming driven by STAT3-inhibition/TLR9-activation in vivo. At the transcriptional levels, AML cells isolated from mice after intravenous administration of CpG-STAT3d or leukemia-targeted Stat3 silencing and TLR9 co-stimulation, displayed similar upregulation of myeloid cell differentiation (Irf8, Cebpa, Itgam) and antigen-presentation (Ciita, Il12a, B2m)-related genes with concomitant reduction of leukemia-promoting Runx1. Single-cell transcriptomics revealed that CpG-STAT3d induced multilineage differentiation of AML cells into monocytes/macrophages, erythroblastic and B cell subsets. As shown by an inducible Irf8 silencing in vivo, IRF8 upregulation was critical for monocyte-macrophage differentiation of leukemic cells. TLR9-driven AML cell reprogramming was likely enabled by downregulation of STAT3-controlled methylation regulators, such as DNMT1 and DNMT3. In fact, the combination of DNA methyl transferase (DNMT) inhibition using azacitidine with CpG oligonucleotides alone mimicked CpG-STAT3d effects, resulting in AML cell differentiation, T cell activation, and systemic leukemia regression. These findings highlight immunotherapeutic potential of bi-functional oligonucleotides to unleash TLR9-driven differentiation of leukemic cells by concurrent STAT3 and/or DNMT inhibition.

Current and future immunotherapeutic approaches in pancreatic cancer treatment

Pancreatic cancer is a major cause of cancer-related death, but despondently, the outlook and prognosis for this resistant type of tumor have remained grim for a long time. Currently, it is extremely challenging to prevent or detect it early enough for effective treatment because patients rarely exhibit symptoms and there are no reliable indicators for detection. Most patients have advanced or spreading cancer that is difficult to treat, and treatments like chemotherapy and radiotherapy can only slightly prolong their life by a few months. Immunotherapy has revolutionized the treatment of pancreatic cancer, yet its effectiveness is limited by the tumor's immunosuppressive and hard-to-reach microenvironment. First, this article explains the immunosuppressive microenvironment of pancreatic cancer and highlights a wide range of immunotherapy options, including therapies involving oncolytic viruses, modified T cells (T-cell receptor [TCR]-engineered and chimeric antigen receptor [CAR] T-cell therapy), CAR natural killer cell therapy, cytokine-induced killer cells, immune checkpoint inhibitors, immunomodulators, cancer vaccines, and strategies targeting myeloid cells in the context of contemporary knowledge and future trends. Lastly, it discusses the main challenges ahead of pancreatic cancer immunotherapy.

IRF8-driven reprogramming of the immune microenvironment enhances anti-tumor adaptive immunity and reduces immunosuppression in murine glioblastoma

Background

Glioblastoma (GBM) has a highly immunosuppressive tumor immune microenvironment (TIME), largely mediated by myeloid-derived suppressor cells (MDSCs). Here, we utilized a retroviral replicating vector (RRV) to deliver Interferon Regulatory Factor 8 (IRF8), a master regulator of type 1 conventional dendritic cell (cDC1) development, in a syngeneic murine GBM model. We hypothesized that RRV-mediated delivery of IRF8 could "reprogram" intratumoral MDSCs into antigen-presenting cells (APCs) and thereby restore T-cell responses.

Methods

Effects of RRV-IRF8 on survival and tumor growth kinetics were examined in the SB28 murine GBM model. Immunophenotype was analyzed by flow cytometry and gene expression assays. We assayed functional immunosuppression and antigen presentation by ex vivo T-cell-myeloid co-culture.

Results

Mice with RRV-IRF8 pre-transduced intracerebral tumors had significantly longer survival and slower tumor growth compared to controls. RRV-IRF8 treated tumors exhibited significant enrichment of cDC1s and CD8+ T-cells. Additionally, myeloid cells derived from RRV-IRF8 tumors showed decreased expression of the immunosuppressive markers Arg1 and IDO1 and demonstrated reduced suppression of naïve T-cell proliferation in ex vivo co-culture, compared to controls. Furthermore, DCs from RRV-IRF8 tumors showed increased antigen presentation compared to those from control tumors. In vivo treatment with azidothymidine (AZT), a viral replication inhibitor, showed that IRF8 transduction in both tumor and non-tumor cells is necessary for survival benefit, associated with a reprogrammed, cDC1- and CD8 T-cell-enriched TIME.

Conclusions

Our results indicate that reprogramming of glioma-infiltrating myeloid cells by in vivo expression of IRF8 may reduce immunosuppression and enhance antigen presentation, achieving improved tumor control.

Sendai virus is robust and consistent in delivering genes into human pancreatic cancer cells

Background

Pancreatic ductal adenocarcinoma (PDAC) is a highly intratumorally heterogeneous disease that includes several subtypes and is highly plastic. Effective gene delivery to all PDAC cells is essential for modulating gene expression and identifying potential gene-based therapeutic targets in PDAC. Most current gene delivery systems for pancreatic cells are optimized for islet or acinar cells. Lentiviral vectors are the current main gene delivery vectors for PDAC, but their transduction efficiencies vary depending on pancreatic cell type, and are especially poor for the classical subtype of PDAC cells from both primary tumors and cell lines.

Methods

We systemically compare transduction efficiencies of glycoprotein G of vesicular stomatitis virus (VSV-G)-pseudotyped lentiviral and Sendai viral vectors in human normal pancreatic ductal and PDAC cells.

Results

We find that the Sendai viral vector gives the most robust gene delivery efficiency regardless of PDAC cell type. Therefore, we propose using Sendai viral vectors to transduce ectopic genes into PDAC cells.

Glioblastoma vaccines: past, present, and opportunities

Glioblastoma (GBM) is one of the most lethal central nervous systems (CNS) tumours in adults. As supplements to standard of care (SOC), various immunotherapies improve the therapeutic effect in other cancers. Among them, tumour vaccines can serve as complementary monotherapy or boost the clinical efficacy with other immunotherapies, such as immune checkpoint blockade (ICB) and chimeric antigen receptor T cells (CAR-T) therapy. Previous studies in GBM therapeutic vaccines have suggested that few neoantigens could be targeted in GBM due to low mutation burden, and single-peptide therapeutic vaccination had limited efficacy in tumour control as monotherapy. Combining diverse antigens, including neoantigens, tumour-associated antigens (TAAs), and pathogen-derived antigens, and optimizing vaccine design or vaccination strategy may help with clinical efficacy improvement. In this review, we discussed current GBM therapeutic vaccine platforms, evaluated and potential antigenic targets, current challenges, and perspective opportunities for efficacy improvement.

A review on gene regulatory network reconstruction algorithms based on single cell RNA sequencing

BACKGROUND

Understanding gene regulatory networks (GRNs) is essential for unraveling the molecular mechanisms governing cellular behavior. With the advent of high-throughput transcriptome measurement technology, researchers have aimed to reverse engineer the biological systems, extracting gene regulatory rules from their outputs, which represented by gene expression data. Bulk RNA sequencing, a widely used method for measuring gene expression, has been employed for GRN reconstruction. However, it falls short in capturing dynamic changes in gene expression at the level of individual cells since it averages gene expression across mixed cell populations.

OBJECTIVE

In this review, we provide an overview of 15 GRN reconstruction tools and discuss their respective strengths and limitations, particularly in the context of single cell RNA sequencing (scRNA-seq).

METHODS

Recent advancements in scRNA-seq break new ground of GRN reconstruction. They offer snapshots of the individual cell transcriptomes and capturing dynamic changes. We emphasize how these technological breakthroughs have enhanced GRN reconstruction.

CONCLUSION

GRN reconstructors can be classified based on their requirement for cellular trajectory, which represents a dynamical cellular process including differentiation, aging, or disease progression. Benchmarking studies support the superiority of GRN reconstructors that do not require trajectory analysis in identifying regulator-target relationships. However, methods equipped with trajectory analysis demonstrate better performance in identifying key regulatory factors. In conclusion, researchers should select a suitable GRN reconstructor based on their specific research objectives.

Programming human cell fate: overcoming challenges and unlocking potential through technological breakthroughs

In recent years, there have been notable advancements in the ability to programme human cell identity, enabling us to design and manipulate cell function in a Petri dish. However, current protocols for generating target cell types often lack efficiency and precision, resulting in engineered cells that do not fully replicate the desired identity or functional output. This applies to different methods of cell programming, which face similar challenges that hinder progress and delay the achievement of a more favourable outcome. However, recent technological and analytical breakthroughs have provided us with unprecedented opportunities to advance the way we programme cell fate. The Company of Biologists' 2023 workshop on 'Novel Technologies for Programming Human Cell Fate' brought together experts in human cell fate engineering and experts in single-cell genomics, manipulation and characterisation of cells on a single (sub)cellular level. Here, we summarise the main points that emerged during the workshop's themed discussions. Furthermore, we provide specific examples highlighting the current state of the field as well as its trajectory, offering insights into the potential outcomes resulting from the application of these breakthrough technologies in precisely engineering the identity and function of clinically valuable human cells.

Reprogramming Cancer Cells to Antigen-presenting Cells

Cancer cells evade the immune system by downregulating antigen presentation. Although immune checkpoint inhibitors (ICI) and adoptive T-cell therapies revolutionized cancer treatment, their efficacy relies on the intrinsic immunogenicity of tumor cells and antigen presentation by dendritic cells. Here, we describe a protocol to directly reprogram murine and human cancer cells into tumor-antigen-presenting cells (tumor-APCs), using the type 1 conventional dendritic cell (cDC1) transcription factors PU.1, IRF8, and BATF3 delivered by a lentiviral vector. Tumor-APCs acquire a cDC1 cell-like phenotype, transcriptional and epigenetic programs, and function within nine days (Zimmermannova et al., 2023). Tumor-APCs express the hematopoietic marker CD45 and acquire the antigen presentation complexes MHC class I and II as well as co-stimulatory molecules required for antigen presentation to T cells, but do not express high levels of negative immune checkpoint regulators. Enriched tumor-APCs present antigens to Naïve CD8+ and CD4+ T cells, are targeted by activated cytotoxic T lymphocytes, and elicit anti-tumor responses in vivo. The tumor-APC reprogramming protocol described here provides a simple and robust method to revert tumor evasion mechanisms by increasing antigen presentation in cancer cells. This platform has the potential to prime antigen-specific T-cell expansion, which can be leveraged for developing new cancer vaccines, neoantigen discovery, and expansion of tumor-infiltrating lymphocytes. Key features • This protocol describes the generation of antigen-presenting cells from cancer cells by direct reprogramming using lineage-instructive transcription factors of conventional dendritic cells type I. • Verification of reprogramming efficiency by flow cytometry and functional assessment of tumor-APCs by antigen presentation assays.