A plant-expressed conjugate vaccine breaks CD4(+) tolerance and induces potent immunity against metastatic Her2(+) breast cancer

TGF-β1 activates neutrophil signaling and gene expression but not migration

Tumor-associated neutrophils are found in many types of cancer and are often reported to contribute to negative outcomes. The presence of transforming growth factor-beta (TGF-β) in the tumor microenvironment reportedly contributes to the skewing of neutrophils to a more pro-tumor phenotype. The effects of TGF-β on neutrophil signaling and migration are, however, unclear. We sought to characterize TGF-β signaling in both primary human neutrophils and the neutrophil-like cell line HL-60 and determine whether it directly induces neutrophil migration. We found that TGF-β1 does not induce neutrophil chemotaxis in transwell or underagarose migration assays. TGF-β1 does activate canonical signaling through SMAD3 and noncanonical signaling through ERK1/2 in neutrophils in a time-and dose-dependent manner. Additionally, TGF-β1 present in the tumor-conditioned media (TCM) of invasive breast cancer cells results in SMAD3 activation. We discovered that TCM induces neutrophils to secrete leukotriene B 4 (LTB 4 ), which is a lipid mediator important for amplifying the range of neutrophil recruitment. However, TGF-β1 alone does not induce secretion of LTB 4 . RNA-sequencing revealed that TGF-β1 and TCM alter gene expression in HL-60 cells, including the mRNA levels of the pro-tumor oncostatin M ( OSM ) and vascular endothelial growth factor A ( VEGFA ). These new insights into the role and impact of TGF-β1 on neutrophil signaling, migration, and gene expression have significant implications in the understanding of the changes in neutrophils that occur in the tumor microenvironment.

Epigenetic modulation of neuroblastoma enhances T cell and NK cell immunogenicity by inducing a tumor-cell lineage switch

BACKGROUND

Immunotherapy in high-risk neuroblastoma (HR-NBL) does not live up to its full potential due to inadequate (adaptive) immune engagement caused by the extensive immunomodulatory capacity of HR-NBL. We aimed to tackle one of the most notable immunomodulatory processes in neuroblastoma (NBL), absence of major histocompatibility complex class I (MHC-I) surface expression, a process greatly limiting cytotoxic T cell engagement. We and others have previously shown that MHC-I expression can be induced by cytokine-driven immune modulation. Here, we aimed to identify tolerable pharmacological repurposing strategies to upregulate MHC-I expression and therewith enhance T cell immunogenicity in NBL.

METHODS

Drug repurposing libraries were screened to identify compounds enhancing MHC-I surface expression in NBL cells using high-throughput flow cytometry analyses optimized for adherent cells. The effect of positive hits was confirmed in a panel of NBL cell lines and patient-derived organoids. Compound-treated NBL cell lines and organoids were cocultured with preferentially expressed antigen of melanoma (PRAME)-reactive tumor-specific T cells and healthy-donor natural killer (NK) cells to determine the in vitro effect on T cell and NK cell cytotoxicity. Additional immunomodulatory effects of histone deacetylase inhibitors (HDACi) were identified by transcriptome and translatome analysis of treated organoids.

RESULTS

Drug library screening revealed MHC-I upregulation by inhibitor of apoptosis inhibitor (IAPi)- and HDACi drug classes. The effect of IAPi was limited due to repression of nuclear factor kappa B (NFκB) pathway activity in NBL, while the MHC-I-modulating effect of HDACi was widely translatable to a panel of NBL cell lines and patient-derived organoids. Pretreatment of NBL cells with the HDACi entinostat enhanced the cytotoxic capacity of tumor-specific T cells against NBL in vitro, which coincided with increased expression of additional players regulating T cell cytotoxicity (eg, TAP1/2 and immunoproteasome subunits). Moreover, MICA and MICB, important in NK cell cytotoxicity, were also increased by entinostat exposure. Intriguingly, this increase in immunogenicity was accompanied by a shift toward a more mesenchymal NBL cell lineage.

CONCLUSIONS

This study indicates the potential of combining (immuno)therapy with HDACi to enhance both T cell-driven and NKcell-driven immune responses in patients with HR-NBL.

Potent anti-tumor immune response and tumor growth inhibition induced by HER2 subdomain fusion protein in a mouse tumor model

PURPOSE

Several approaches have so far been employed to establish anti-tumor immunity by targeting HER2 protein. Active immunization with recombinant HER2 subdomains has previously been demonstrated to induce potent immune response and tumor growth inhibition. In the present study, we investigated the immunogenicity and tumor inhibitory effect of a fusion protein consisting of human HER2 extracellular subdomain (ECD-DI + II) together with T-helper cell epitopes of Tetanus toxin (p2 and p30).

METHODS

BALB/c mice were immunized with two recombinant proteins (DI + II and p2p30-DI + II) emulsified in 4 different adjuvants. Anti-DI + II antibody response, cytokine profile, frequency of splenic CD25⁺FOXP3⁺ regulatory T cells (Tregs) and CD8⁺CD107a⁺ cytotoxic T lymphocytes (CTLs) were assessed in the immunized mice. To assess the anti-tumor effect, the immunized mice were subcutaneously challenged with HER2-overexpressing tumor cells and the tumor growth was determined.

RESULTS

Both recombinant proteins were able to induce comparable levels of ECD-DI + II-specific antibodies. Immunization with p2p30-DI + II resulted in a significant increase in the level of Interferon-gamma (IFN-γ) secretion compared to DI + II protein and significantly higher frequency of CTLs and lower frequency of Tregs. The number of mice that remained tumor-free until day 120 was significantly higher in p2p30-DI + II vaccinated groups.

CONCLUSIONS

Our data suggest that the p2p30-DI + II fusion protein together with CpG adjuvant induces more potent anti-tumor immune responses in a mouse tumor model. Accordingly, this formulation might be considered as a potential immunotherapeutic approach in HER2⁺ cancers.

Tetanus Toxin Fragment C: Structure, Drug Discovery Research and Production

Tetanus toxoid (TTd) plays an important role in the pharmaceutical world, especially in vaccines. The toxoid is obtained after formaldehyde treatment of the tetanus toxin. In parallel, current emphasis in the drug discovery field is put on producing well-defined and safer drugs, explaining the interest in finding new alternative proteins. The tetanus toxin fragment C (TTFC) has been extensively studied both as a neuroprotective agent for central nervous system disorders owing to its neuronal properties and as a carrier protein in vaccines. Indeed, it is derived from a part of the tetanus toxin and, as such, retains its immunogenic properties without being toxic. Moreover, this fragment has been well characterized, and its entire structure is known. Here, we propose a systematic review of TTFC by providing information about its structural features, its properties and its methods of production. We also describe the large uses of TTFC in the field of drug discovery. TTFC can therefore be considered as an attractive alternative to TTd and remarkably offers a wide range of uses, including as a carrier, delivery vector, conjugate, booster, inducer, and neuroprotector.

Chloroplast Engineering: Fundamental Insights and Its Application in Amelioration of Environmental Stress

Chloroplasts are specialized organelle that are responsible for converting light energy to chemical energy, thereby driving the carbon dioxide fixation. Apart from photosynthesis, chloroplast is the site for essential cellular processes that determine the plant adaptation to changing environment. Owing to the presence of their own expression system, it provides an optimum platform for engineering valued traits as well as site for synthesis of bio-compounds. Advancements in technology have further enhanced the scope of using chloroplast as a multifaceted tool for the biotechnologist to develop stress-tolerant plants and ameliorate environmental stress. Focusing on chloroplast biotechnology, this review discusses the advances in chloroplast engineering and its application in enhancing plant adaptation and resistance to environmental stress and the development of new bioproducts and processes. This is accomplished through analysis of its biogenesis and physiological processes, highlighting the chloroplast engineering and recent developments in chloroplast biotechnology. In the first part of the review, the evolution and principles of structural organization and physiology of chloroplast are discussed. In the second part, the chief methods and mechanisms involved in chloroplast transformation are analyzed. The last part represents an updated analysis of the application of chloroplast engineering in crop improvement and bioproduction of industrial and health compounds.

Computational image features of immune architecture is associated with clinical benefit and survival in gynecological cancers across treatment modalities

BACKGROUND

We present a computational approach (ArcTIL) for quantitative characterization of the architecture of tumor-infiltrating lymphocytes (TILs) and their interplay with cancer cells from digitized H&E-stained histology whole slide images and evaluate its prognostic role in three different gynecological cancer (GC) types and across three different treatment types (platinum, radiation and immunotherapy).

METHODS

In this retrospective study, we included 926 patients with GC diagnosed with ovarian cancer (OC), cervical cancer, and endometrial cancer with available digitized diagnostic histology slides and survival outcome information. ArcTIL features quantifying architecture and spatial interplay between immune cells and the rest of nucleated cells (mostly comprised cancer cells) were extracted from the cell cluster graphs of nuclei within the tumor epithelial nests, surrounding stroma and invasive tumor front compartments on H&E-stained slides. A Cox proportional hazards model, incorporating ArcTIL features was fit on the OC training cohort (N=51), yielding an ArcTIL signature. A unique threshold learned from the training set stratified the patients into a low and high-risk group.

RESULTS

The seven feature ArcTIL classifier was found to significantly correlate with overall survival in chemotherapy and radiotherapy-treated validation cohorts and progression-free survival in an immunotherapy-treated validation cohort. ArcTIL features relating to increased density of TILs in the epithelium and invasive tumor front were found to be associated with better survival outcomes when compared with those patients with an increased TIL density in the stroma. A statistically significant association was found between the ArcTIL signature and signaling pathways for blood vessel morphogenesis, vasculature development, regulation of cell differentiation, cell-substrate adhesion, biological adhesion, regulation of vasculature development, and angiogenesis.

CONCLUSIONS

This study reveals that computationally-derived features from the spatial architecture of TILs and tumor cells are prognostic in GCs treated with chemotherapy, radiotherapy, and checkpoint blockade and are closely associated with central biological processes that impact tumor progression. These findings could aid in identifying therapy-refractory patients and further enable personalized treatment decision-making.

Plant-based vaccines and cancer therapy: Where are we now and where are we going?

Therapeutic vaccines are an effective approach in cancer therapy for treating the disease at later stages. The Food and Drug Administration (FDA) recently approved the first therapeutic cancer vaccine, and further studies are ongoing in clinical trials. These are expected to result in the future development of vaccines with relatively improved efficacy. Several vaccination approaches are being studied in pre-clinical and clinical trials, including the generation of anti-cancer vaccines by plant expression systems.This approach has advantages, such as high safety and low costs, especially for the synthesis of recombinant proteins. Nevertheless, the development of anti-cancer vaccines in plants is faced with some technical obstacles.Herein, we summarize some vaccines that have been used in cancer therapy, with an emphasis on plant-based vaccines.

Expression and immunogenicity assessment of a plant-made immunogen targeting the cytotoxic T-lymphocyte associated antigen-4: a possible approach for cancer immunotherapy

Cancer immunotherapy is a promising intervention to fight against this global health problem. In particular targeting immune checkpoints, such as cytotoxic T-lymphocyte associated antigen-4 (CTLA-4) and programmed-death protein 1 (PD-1), by specific monoclonal antibodies is a current treatment for many malignances. A possible innovation in this field is based on the induction of humoral responses in the host by suppressing the effects of such immune checkpoints and as consequence favoring the activation of cellular immunity against the tumor cells. In this study, chimeric protein comprising the B subunit of Escherichia coli heat-labile enterotoxin as carrier and the extracellular domain of CTLA-4 (LTB-CTLA4) was produced in Nicotiana benthamiana by transient expression. The recombinant protein was accumulated up to 1.29 μg/g of leaves fresh weight on 4 day-post-infiltration. The integrity of the plant-made LTB-CTLA4 antigen was confirmed by western blot analysis and ELISA. Immunogenicity of the plant-made LTB-CTLA4 was assessed in BALB/c mice and the results showed that humoral responses were induced against both the LTB and CTLA-4 moieties. The plant-made LTB-CTLA4 stands as a promising candidate for the design of advanced protection studies against cancer in murine models.

Breast cancer-induced immune suppression in the sentinel lymph node is effectively countered by CpG-B in conjunction with inhibition of the JAK2/STAT3 pathway

BACKGROUND

We previously showed selectively hampered activation of lymph node-resident (LNR) dendritic cell (DC) subsets in the breast cancer (BrC) sentinel lymph node (SLN) to precede a state of profound T cell anergy. Reactivating these DC subsets by intratumoral delivery of the Toll-like receptor-9 (TLR9) agonist CpG-B could potentially offer a promising immune therapeutic strategy to combat this immune suppression and prevent disease spread. Unfortunately, CpG-B can limit its own immune stimulatory activity through direct TLR9-mediated activation of signal transducer and activator of transcription 3 (STAT3), pinpointed as a key regulator of immune suppression in the tumor microenvironment. Here, we have investigated whether in vitro exposure to CpG-B, with or without simultaneous inhibition of STAT3 signaling, could overcome immune suppression in BrC SLN.

METHODS

Immune modulatory effects of CpG-B (CPG7909) with or without the JAK2/STAT3 inhibitor (STAT3i) AG490 were assessed in ex vivo cultured BrC SLN-derived single-cell suspensions (N=29). Multiparameter flow cytometric analyses were conducted for DC and T cell subset characterization and assessment of (intracellular) cytokine profiles. T cell reactivity against the BrC-associated antigen Mammaglobin-A was determined by means of interferon-γ ELISPOT assay.

RESULTS

Although CpG-B alone induced activation of all DC subsets, combined inhibition of the JAK2/STAT3 pathway resulted in superior DC maturation (ie, increased CD83 expression), with most profound activation and maturation of LNR DC subsets. Furthermore, combined CpG-B and JAK2/STAT3 inhibition promoted Th1 skewing by counterbalancing the CpG-induced Th2/regulatory T cell response and significantly enhanced Mammaglobin-A specific T cell reactivity.

CONCLUSION

Ex vivo immune modulation of the SLN by CpG-B and simultaneous JAK2/STAT3 inhibition can effectively overcome BrC-induced immune suppression by preferential activation of LNR DC, ultimately restoring type 1-mediated antitumor immunity, thereby securing a BrC-specific T cell response. These findings provide a clear rationale for clinical exploration of SLN-immune potentiation through local CpG/STAT3i administration in patients with BrC.

NOX4 Inhibition Potentiates Immunotherapy by Overcoming Cancer-Associated Fibroblast-Mediated CD8 T-cell Exclusion from Tumors

Determining mechanisms of resistance to αPD-1/PD-L1 immune-checkpoint immunotherapy is key to developing new treatment strategies. Cancer-associated fibroblasts (CAF) have many tumor-promoting functions and promote immune evasion through multiple mechanisms, but as yet, no CAF-specific inhibitors are clinically available. Here we generated CAF-rich murine tumor models (TC1, MC38, and 4T1) to investigate how CAFs influence the immune microenvironment and affect response to different immunotherapy modalities [anticancer vaccination, TC1 (HPV E7 DNA vaccine), αPD-1, and MC38] and found that CAFs broadly suppressed response by specifically excluding CD8+ T cells from tumors (not CD4+ T cells or macrophages); CD8+ T-cell exclusion was similarly present in CAF-rich human tumors. RNA sequencing of CD8+ T cells from CAF-rich murine tumors and immunochemistry analysis of human tumors identified significant upregulation of CTLA-4 in the absence of other exhaustion markers; inhibiting CTLA-4 with a nondepleting antibody overcame the CD8+ T-cell exclusion effect without affecting Tregs. We then examined the potential for CAF targeting, focusing on the ROS-producing enzyme NOX4, which is upregulated by CAF in many human cancers, and compared this with TGFβ1 inhibition, a key regulator of the CAF phenotype. siRNA knockdown or pharmacologic inhibition [GKT137831 (Setanaxib)] of NOX4 "normalized" CAF to a quiescent phenotype and promoted intratumoral CD8+ T-cell infiltration, overcoming the exclusion effect; TGFβ1 inhibition could prevent, but not reverse, CAF differentiation. Finally, NOX4 inhibition restored immunotherapy response in CAF-rich tumors. These findings demonstrate that CAF-mediated immunotherapy resistance can be effectively overcome through NOX4 inhibition and could improve outcome in a broad range of cancers. SIGNIFICANCE: NOX4 is critical for maintaining the immune-suppressive CAF phenotype in tumors. Pharmacologic inhibition of NOX4 potentiates immunotherapy by overcoming CAF-mediated CD8+ T-cell exclusion. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/9/1846/F1.large.jpg.See related commentary by Hayward, p. 1799.

Linked CD4 T Cell Help: Broadening Immune Attack Against Cancer by Vaccination

In the last decade, immunotherapy with monoclonal antibodies targeting immunological check points has become a breakthrough therapeutic modality for solid cancers. However, only up to 50 % of patients benefit from this powerful approach. For others vaccination might provide a plausible addition or alternative. For induction of effective anticancer immunity CD4+ T cell help is required, which is often difficult to induce to self cancer targets because of tolerogenic mechanisms. Our approach for cancer vaccines has been to incorporate into the vaccine design sequences able to activate foreign T cell help, through genetically linking cancer targets to microbial sequences (King et al. in Nat Med 4(11):1281-1286, 1998; Savelyeva et al. in Nat Biotechnol 19(8):760-764, 2001). This harnesses the non-tolerized CD4 T cell repertoire available in patients to help induction of effective immunity against fused cancer antigens. Multiple immune effector mechanisms including antibody, CD8+ T cells as well as CD4 effector T cells can be activated using this strategy. Delivery via DNA vaccines has already indicated clinical efficacy. The same principle of linked T cell help has now been transferred to other novel vaccine modalities to further potentiate immunity against cancer targets.

Intrastructural Help: Harnessing T Helper Cells Induced by Licensed Vaccines for Improvement of HIV Env Antibody Responses to Virus-Like Particle Vaccines

Induction of persistent antibody responses by vaccination is generally thought to depend on efficient help by T follicular helper cells. Since the T helper cell response to HIV Env may not be optimal, we explored the possibility of improving the HIV Env antibody response to virus-like particle (VLP) vaccines by recruiting T helper cells induced by commonly used licensed vaccines to provide help for Env-specific B cells. B cells specific for the surface protein of a VLP can internalize the entire VLP and thus present peptides derived from the surface and core proteins on their major histocompatibility complex class II (MHC-II) molecules. This allows T helper cells specific for the core protein to provide intrastructural help for B cells recognizing the surface protein. Consistently, priming mice with an adjuvanted Gag protein vaccine enhanced the HIV Env antibody response to subsequent booster immunizations with HIV VLPs. To harness T helper cells induced by the licensed Tetanolpur vaccines, HIV VLPs that contained T helper cell epitopes of tetanus toxoid were generated. Tetanol-immunized mice raised stronger antibody responses to immunizations with VLPs containing tetanus toxoid T helper cell epitopes but not to VLPs lacking these epitopes. Depending on the priming immunization, the IgG subtype response to HIV Env after the VLP immunization could also be modified. Thus, harnessing T helper cells induced by other vaccines appears to be a promising approach to improve the HIV Env antibody response to VLP vaccines.

IMPORTANCE Induction of HIV Env antibodies at sufficient levels with optimal Fc effector functions for durable protection remains a challenge. Efficient T cell help may be essential to induce such a desirable antibody response. Here, we provide proof of concept that T helper cells induced by a licensed vaccine can be harnessed to provide help for HIV Env-specific B cells and to modulate the Env-specific IgG subtype response.

Linear doggybone DNA vaccine induces similar immunological responses to conventional plasmid DNA independently of immune recognition by TLR9 in a pre-clinical model

Vaccination with DNA that encodes cancer antigens is a simple and convenient way to raise immunity against cancer and has already shown promise in the clinical setting. Conventional plasmid DNA is commonly used which together with the encoded antigen also includes bacterial immunostimulatory CpG motifs to target the DNA sensor Toll-like receptor 9. Recently DNA vaccines using doggybone DNA (dbDNA™), have been developed without the use of bacteria. The cell-free process relies on the use of Phi29 DNA polymerase to amplify the template followed by protelomerase TelN to complete individual closed linear DNA. The resulting DNA contains the required antigenic sequence, a promoter and a poly A tail but lacks bacterial sequences such as an antibiotic resistance gene, prompting the question of immunogenicity. Here we compared the ability of doggybone DNA vaccine with plasmid DNA vaccine to induce adaptive immunity using clinically relevant oncotargets E6 and E7 from HPV. We demonstrate that despite the inability to trigger TLR9, doggybone DNA was able to induce similar levels of cellular and humoral immunity as plasmid DNA, with suppression of established TC-1 tumours.

Repurposing Plant Virus Nanoparticles

Plants have been explored for many years as inexpensive and versatile platforms for the generation of vaccines and other biopharmaceuticals. Plant viruses have also been engineered to either express subunit vaccines or act as epitope presentation systems. Both icosahedral and helical, filamentous-shaped plant viruses have been used for these purposes. More recently, plant viruses have been utilized as nanoparticles to transport drugs and active molecules into cancer cells. The following review describes the use of both icosahedral and helical plant viruses in a variety of new functions against cancer. The review illustrates the breadth of variation among different plant virus nanoparticles and how this impacts the immune response.

Reconceptualizing cancer immunotherapy based on plant production systems

Plants can be used as inexpensive and facile production platforms for vaccines and other biopharmaceuticals. More recently, plant-based biologics have expanded to include cancer immunotherapy agents. The following review describes the current state of the art for plant-derived strategies to prevent or reduce cancers. The review discusses avenues taken to prevent infection by oncogenic viruses, solid tumors and lymphomas. Strategies including cancer vaccines, monoclonal antibodies and virus nanoparticles are described, and examples are provided. The review ends with a discussion of the implications of plant-based cancer immunotherapy for developing countries.

Cancer immunotherapy has made great strides over recent years. This review describes the use of plants as production systems to produce biopharmaceuticals such as vaccines and antibodies to treat a wide variety of cancers. The use of nanoparticle technology based on plant viruses as a novel strategy to target and combat cancers is also included. The review concludes with a discussion of plant production platforms and their relevance for the generation of cheap and effective cancer immunotherapies for developing countries.

Production of Recombinant Anti-Cancer Vaccines in Plants

Plant expression systems have been developed to produce anti-cancer vaccines. Plants have several advantages as bioreactors for the production of subunit vaccines: they are considered safe, and may be used to produce recombinant proteins at low production cost. However, several technical issues hinder large-scale production of anti-cancer vaccines in plants. The present review covers design strategies to enhance the immunogenicity and therapeutic potency of anti-cancer vaccines, methods to increase vaccine-expressing plant biomass, and challenges facing the production of anti-cancer vaccines in plants. Specifically, the issues such as low expression levels and plant-specific glycosylation are described, along with their potential solutions.