Immunogenic Antigens Research Articles

CTIM-11. LONG-TERM SURVIVORS FROM A PHASE 1B STUDY OF IGV-001 IN PATIENTS WITH NEWLY DIAGNOSED GLIOBLASTOMA

Abstract Imvax has developed the Goldspire™ platform to create IGV-001, an autologous biologic-device combination product for the treatment of newly diagnosed glioblastoma (ndGBM). IGV-001 consists of autologous GBM tumor cells and an antisense oligonucleotide against IGF-1R mRNA (IMV-001), irradiated and administered via biodiffusion chambers (BDCs) implanted in the abdomen. Together, these components stimulate immunogenic cell death and antigen release. IGV-001 was well tolerated and multiple efficacy signals were observed in a Phase 1b study in patients with ndGBM (Andrews et al., 2021), including significant improvements in progression-free survival (PFS), radiographic evidence of tumor response, and changes in immune response biomarkers. The Phase 1b study enrolled 33 patients in four different cohorts implanted with 10 or 20 BDCs for 24 or 48 hours. Here we report on 6 subjects with survival beyond 4 years, including 5 subjects who survived 5 years or more (15.2%). There were 4 male and 2 female subjects, with a median age of 52 years (range 32-75). At diagnosis the MGMT promoter was methylated in 4 of 5 subjects that survived 5 years or more. We also report on T cell receptor Vβ CDR3 region sequencing of peripheral blood mononuclear cells and tissue infiltrated lymphocytes that was performed in a subset of 9 patients, including 3 subjects who survived beyond 4 years. Immune correlates of IGV-001 suggest an association between peripheral T cell clonal expansion and PFS/OS outcomes. A Phase 2b randomized, multicenter, double-blind, placebo-controlled study to assess the safety and efficacy of IGV-001 in patients with ndGBM (NCT04485949) has completed enrollment and results are expected to be available in 2025.

Diphtheria Toxoid-Derived T-Helper Epitope and α-galactosylceramide Synergistically Enhance the Immunogenicity of Glycopeptide Antigen

Diphtheria Toxoid-Derived T-Helper Epitope and α-galactosylceramide Synergistically Enhance the Immunogenicity of Glycopeptide Antigen

Improvement of RBD-FC Immunogenicity by Using Alum-Sodium Alginate Adjuvant Against SARS-COV-2.

Adjuvants use several mechanisms to boost immunogenicity and to modulate immune response. The strength of adsorption of antigen by adjuvants can be a determinant factor for significant improvement of immunopotentiation. We expressed recombinant RBD-FC in PichiaPink Strain 4 and examined the vaccination of mice by vaccine formulation with different adjuvants (sodium alginate and aluminum hydroxide, alone and together). Sodium alginate significantly increased the immunogenicity and stability of RBD-FC antigen, so RBD-FC formulated with combined alginate and alum (AlSa) and sodium alginate alone showed higher antibody titer and stability. Immunogenicity of RBD-FC:AlSa was determined by serological assays including direct enzyme-linked immunosorbent assay (ELISA) and surrogate virus neutralization test (sVNT). High levels of IgGs and neutralizing antibodies were measured in serum of mice immunized with the RBD-FC:AlSa formulation. On the other hand, cytokines IL-10 and INF-γ were severely accumulated in response to RBD-FC:AlSa, and after 10 days, their accumulation was significantly declined, whereas IL-4 showed the highest and the lowest accumulation in response to alum and alginate, respectively. Our data may suggest that combination of alum and sodium alginate has a better compatibility with RBD-FC in vaccine formulation.

Evaluation of the Use of Sub-Immunodominant Antigens of Babesia bovis with Flagellin C Adjuvant in Subunit Vaccine Development

Bovine babesiosis caused by the tick-borne apicomplexan parasite Babesia bovis remains a threat for cattle worldwide, and new vaccines are needed. We propose using immune-subdominant (ISD) antigens as alternative vaccine candidates. We first determined that RAP-1 NT and RRA are subdominant antigens using recombinant antigens in ELISAs against sera from B. bovis-protected cattle. Protected animals demonstrated high antibody responses against the known immunodominant rRAP-1 CT antigen, but significantly lower levels against the rRAP-1 NT and rRRA antigens. Next, a group of cattle (n = 6) was vaccinated with rRRA and rRAP-1 NT using a FliC–Emulsigen mix as the adjuvant, and there was a control group (n = 6) with the adjuvant mix alone. All but one immunized animal demonstrated elicitation of strong humoral immune responses against the two ISD antigens. Acute babesiosis occurred in both groups of cattle upon a challenge with the virulent B. bovis, but a significant delay in the average rate of decrease in hematocrit in the vaccinated group, and an early monocyte response, was found in half of the vaccinated animals. In conclusion, we confirmed the immune subdominance of rRRA and rRAP-1 NT and the ability of FliC to increase immunogenicity of ISD antigens and generate useful information toward developing future subunit vaccines against B. bovis.

Comparative Efficacy of Parenteral and Mucosal Recombinant Probiotic Vaccines Against SARS-CoV-2 and S. pneumoniae Infections in Animal Models.

The accumulation of specific IgG antibodies in blood serum is considered a key criterion for the effectiveness of vaccination. For several vaccine-preventable infections, quantitative indicators of the humoral response have been established, which, when reached, provide a high probability of protection against infection. The presence of such a formal correlate of vaccine effectiveness is crucial, for example, in organizing preventive measures and validating newly developed vaccines. However, can effective protection against infection occur when the level of serum antibodies is lower than that provided by parenteral vaccination? Will protection be sufficient if the same vaccine antigen is administered via mucosal membranes without achieving high levels of specific IgG circulating in the blood? In this study, we compared the immunogenicity and protective efficacy of parenteral and mucosal forms of vaccines in experimental animals, targeting infections caused by the SARS-CoV-2 coronavirus and Streptococcus pneumoniae. We investigated the protective properties of a fragment of the coronavirus S1 protein administered intramuscularly with an adjuvant and orally as part of the probiotic strain Enterococcus faecium L3 in a Syrian hamster model. A comparative assessment of the immunogenicity and protective efficacy of a recombinant tandem (PSP) of immunogenic peptides from S. pneumoniae surface proteins, administered either parenterally or orally, was performed in a Balb/c mouse model. Both models demonstrated significant differences in the immunogenicity of parenteral and oral vaccine antigens, but comparable protective efficacy.

Triple-negative breast cancer-derived exosomes change the immunological features of human monocyte-derived dendritic cells and influence T-cell responses.

Triple-negative breast cancer (TNBC) exhibits a lower survival rate in comparison to other BC subtypes. Utilizing dendritic cell (DC) vaccines as a form of immunotherapy is becoming a promising new approach to cancer treatment. However, inadequate immunogenicity of tumor antigens leads to unsatisfactory effectiveness of the DC vaccines. Exosomes are the basis for the latest improvements in tumor immunotherapy. This study examined whether TNBC-derived exosomes elicit immunogenicity on the maturation and function of monocyte-derived DCs and the impact of the exosome-treated monocyte-derived DCs (moDCs) on T cell differentiation. exosomes were isolated from MDA-MB-231 TNBC cancer cells and characterized. Monocytes were separated from peripheral blood mononuclear cells and differentiated into DCs. Then, monocyte-derived DCs were treated with TNBC-derived exosomes. Furthermore, the mRNA levels of the genes and cytokines involved in DC maturation and function were examined using qRT-PCR and ELISA assays. We also cocultured TNBC-derived exosome-treated moDCs with T cells and investigated the role of the treatment in T cell differentiation by evaluating the expression of some related genes by qRT-PCR. The concentration of the cytokines secreted from T cells cocultured with exosome-treated moDCs was quantified by the ELISA assays. Our findings showed that TNBC-derived exosomes induce immunogenicity by enhancing moDCs' maturation and function. In addition, exosome-treated moDCs promote cocultured T-cell expansion by inducing TH1 differentiation through increasing cytokine production. TNBC-derived exosomes could improve vaccine-elicited immunotherapy by inducing an immunogenic response and enhancing the effectiveness of the DC vaccines. However, this needs to be investigated further in future studies.

A plant-based oligomeric CD2v extracellular domain antigen exhibits equivalent immunogenicity to the live attenuated vaccine ASFV-G-∆I177L.

African swine fever (ASF), caused by the African swine fever virus (ASFV), is a deadly, highly contagious disease in both domestic pigs and wild boar. With mortality up to 100%, the disease has been making a serious impact on the swine industry worldwide. Because no effective antiviral treatment has been observed, proactive prevention such as vaccination remains the key to controlling the outbreak. In the pursuit of expediting vaccine development, our current work has made the first report for heterologous production of the viral outer envelope glycoprotein CD2v extracellular domain (CD2v ED), a proposed promising vaccine antigen candidate in the "green" synthetic host Nicotiana benthamiana. Protein oligomerization strategies were implemented to increase the immunogenicity of the target antigen. Herein, the protein was expressed in oligomeric forms based on the C-terminally fused GCN4pII trimerization motif and GCN4pII_TP oligomerization motif. Quantitative western blot analysis showed significantly higher expression of trimeric CD2v ED_GCN4pII with a yield of about 12mg/100g of fresh weight, in comparison to oligomeric CD2v ED_GCN4pII_TP, revealing the former is the better choice for further studies. The results of purification and size determination by size exclusion chromatography (SEC) illustrated that CD2v ED_GCN4pII was successfully produced in stable oligomeric forms throughout the extraction, purification, and analysis process. Most importantly, purified CD2v ED_GCN4pII was demonstrated to induce both humoral and cellular immunity responses in mice to extents equivalent to those of the live attenuated vaccine ASFV-G-∆I177L, suggesting it as the potential subunit vaccine candidate for preventing ASFV.

A mathematical model simulating the adaptive immune response in various vaccines and vaccination strategies

Vaccination has been widely recognized as an effective measure for preventing infectious diseases. To facilitate quantitative research into the activation of adaptive immune responses in the human body by vaccines, it is important to develop an appropriate mathematical model, which can provide valuable guidance for vaccine development. In this study, we constructed a novel mathematical model to simulate the dynamics of antibody levels following vaccination, based on principles from immunology. Our model offers a concise and accurate representation of the kinetics of antibody response. We conducted a comparative analysis of antibody dynamics within the body after administering several common vaccines, including traditional inactivated vaccines, mRNA vaccines, and future attenuated vaccines based on defective interfering viral particles (DVG). Our findings suggest that booster shots play a crucial role in enhancing Immunoglobulin G (IgG) antibody levels, and we provide a detailed discussion on the advantages and disadvantages of different vaccine types. From a mathematical standpoint, our model proposes four essential approaches to guide vaccine design: enhancing antigenic T-cell immunogenicity, directing the production of high-affinity antibodies, reducing the rate of IgG decay, and lowering the peak level of vaccine antigen-antibody complexes. Our study contributes to the understanding of vaccine design and its application by explaining various phenomena and providing guidance in comprehending the interactions between antibodies and antigens during the immune process.

A comprehensive proteogenomic pipeline for neoantigen discovery to advance personalized cancer immunotherapy.

The accurate identification and prioritization of antigenic peptides is crucial for the development of personalized cancer immunotherapies. Publicly available pipelines to predict clinical neoantigens do not allow direct integration of mass spectrometry immunopeptidomics data, which can uncover antigenic peptides derived from various canonical and noncanonical sources. To address this, we present an end-to-end clinical proteogenomic pipeline, called NeoDisc, that combines state-of-the-art publicly available and in-house software for immunopeptidomics, genomics and transcriptomics with in silico tools for the identification, prediction and prioritization of tumor-specific and immunogenic antigens from multiple sources, including neoantigens, viral antigens, high-confidence tumor-specific antigens and tumor-specific noncanonical antigens. We demonstrate the superiority of NeoDisc in accurately prioritizing immunogenic neoantigens over recent prioritization pipelines. We showcase the various features offered by NeoDisc that enable both rule-based and machine-learning approaches for personalized antigen discovery and neoantigen cancer vaccine design. Additionally, we demonstrate how NeoDisc's multiomics integration identifies defects in the cellular antigen presentation machinery, which influence the heterogeneous tumor antigenic landscape.

Implementation of an Immunoassay Based on the MVA-T7pol-Expression System for Rapid Identification of Immunogenic SARS-CoV-2 Antigens: A Proof-of-Concept Study.

The emergence of hitherto unknown viral pathogens presents a great challenge for researchers to develop effective therapeutics and vaccines within a short time to avoid an uncontrolled global spread, as seen during the coronavirus disease 2019 (COVID-19) pandemic. Therefore, rapid and simple methods to identify immunogenic antigens as potential therapeutical targets are urgently needed for a better pandemic preparedness. To address this problem, we chose the well-characterized Modified Vaccinia virus Ankara (MVA)-T7pol expression system to establish a workflow to identify immunogens when a new pathogen emerges, generate candidate vaccines, and test their immunogenicity in an animal model. By using this system, we detected severe acute respiratory syndrome (SARS) coronavirus 2 (SARS-CoV-2) nucleoprotein (N)-, and spike (S)-specific antibodies in COVID-19 patient sera, which is in line with the current literature and our observations from previous immunogenicity studies. Furthermore, we detected antibodies directed against the SARS-CoV-2-membrane (M) and -ORF3a proteins in COVID-19 patient sera and aimed to generate recombinant MVA candidate vaccines expressing either the M or ORF3a protein. When testing our candidate vaccines in a prime-boost immunization regimen in humanized HLA-A2.1-/HLA-DR1-transgenic H-2 class I-/class II-knockout mice, we were able to demonstrate M- and ORF3a-specific cellular and humoral immune responses. Hence, the established workflow using the MVA-T7pol expression system represents a rapid and efficient tool to identify potential immunogenic antigens and provides a basis for future development of candidate vaccines.

A Modified Bleaching Method for Multiplex Immunofluorescence Staining of FFPE Tissue Sections.

Multiplex immunofluorescence (mIF) staining plays an important role in profiling biomarkers and allows investigation of co-relationships between multiple biomarkers in the same tissue section. The Cell DIVE mIF platform (Leica Microsystems) employs an alkaline solution of hydrogen peroxide as a fluorophore inactivation reagent in the sequential staining, imaging, and bleaching protocol for use on FFPE sections. Suboptimal bleaching efficiency, degradation of tissue structure, and loss of antigen immunogenicity occasionally are encountered with the standard bleaching process. To overcome these impediments, we adopted a modified photochemical bleaching method, which utilizes an intense LED light exposure concurrent with the application of hydrogen peroxide. Repeated stain/bleach rounds with different antibodies were performed on breast tissue and other tissue sections. Residual signal after conventional bleaching and the modified technique were compared and tissue integrity and antigen immunogenicity were assessed. The modified technique effectively eliminates fluorescence signal from previous staining rounds and produces consistent results for multiple rounds of staining and imaging. With the modified method, photochemical treatments did not destroy tissue sub-cellular contents, and the tissue antigenicity was well preserved during the entire mIF process. Overall processing time was reduced from 36 to 30 hours in an mIF procedure with 8 rounds. With the conventional method, tissue quality was highly degraded after 8 rounds. The new technique allows reduced turn-around time, provides reliable fluorophore removal in mIF with excellent maintenance of tissue integrity, facilitating studies of the co-localization of multiple biomarkers in tissues of interest.

8074 Investigating Viral Infections, Systemic Inflammation, and their Complex Interplay in Type 1 Diabetes Pathogenesis

Abstract Disclosure: K. Girdhar: None. E. Elko: None. A. Pina: None. M. Atkinson: None. J. Ludvigsson: None. J. Ladner: None. E. Altindis: None. Type 1 diabetes (T1D) is an autoimmune disorder characterized by the immune-mediated destruction of insulin-producing beta cells. The etiological factors triggering the immunogenicity of endogenous β-cell antigens remain a focal point of investigation. Viral infections, particularly enteroviruses, coxsackieviruses, and rotaviruses, have been proposed as potential contributors to T1D onset and progression. However, the causal relationship between viral infections and T1D pathogenesis remains elusive. To address this, we conducted an in-depth analysis of viral infection histories of T1D patients and pediatric T1D progressors compared to the controls. To this end, we employed highly multiplexed serology using PepSeq sequencing, an in vitro platform designed for conducting proteomic assays against customizable targets via DNA-barcoded peptides. Utilizing samples from the All Babies in Sweden (ABIS) study (n=58) and the TrialNet study (n=116 new-onset T1D, n=25 established T1D, n=128 controls), we assessed seropositivity against 79 different human viruses. Contrary to previous reports, no significant differences were identified in viral infection histories between T1D individuals and controls. Subsequent analyses of enriched Peptide Count and Viral Homology Search (VHS) species provided further confirmation of the absence of distinctions in T1D progression. Next, we determined whether there are any differences in the markers of systematic inflammation in spite of their similar viral history profile. Therefore, we employed Luminex assays to investigate cytokine profiles in established T1D individuals (n=25). While we could not identify any differences when we compared T1D patients to controls, we identified notable sex-specific differences. Anti-inflammatory cytokines (IL-4, IL-13, IL-22) were lower in female T1D patients compared to female controls. Likewise, female T1D patients had higher pro-inflammatory cytokines (IL-17E, TNF-β). On the other hand, male T1D patients exhibited increased levels of epidermal growth factor and platelet-derived growth factor compared to male controls, with IL-22 uniquely elevated. Our findings challenge the direct association between viral infections and T1D, highlighting the importance of investigating alternative factors. Moreover, the observed sex-specific cytokine alterations underscore the complex interplay between immune responses and T1D, emphasizing the need for sex-specific therapeutic strategies. This research contributes valuable insights into the intricate dynamics of viral infections, systemic inflammation, and their potential roles in T1D pathogenesis. Presentation: 6/2/2024

Self-assembling nanoparticle engineered from the ferritinophagy complex as a rabies virus vaccine candidate

Over the past decade, there has been a growing interest in ferritin-based vaccines due to their enhanced antigen immunogenicity and favorable safety profiles, with several vaccine candidates targeting various pathogens advancing to phase I clinical trials. Nevertheless, challenges associated with particle heterogeneity, improper assembly and unanticipated immunogenicity due to the bulky protein adaptor have impeded further advancement. To overcome these challenges, we devise a universal ferritin-adaptor delivery platform based on structural insights derived from the natural ferritinophagy complex of the human ferritin heavy chain (FTH1) and the nuclear receptor coactivator 4 (NCOA4). The engineered ferritinophagy (Fagy)-tag peptide demonstrate significantly enhanced binding affinity to the 24-mer ferritin nanoparticle, enabling efficient antigen presentation. Subsequently, we construct a self-assembling rabies virus (RABV) vaccine candidate by noncovalently conjugating the Fagy-tagged glycoprotein domain III (GDIII) of RABV to the ferritin nanoparticle, maintaining superior homogeneity, stability and immunogenicity. This vaccine candidate induces potent, rapid, and durable immune responses, and protects female mice against the authentic RABV challenge after single-dose administration. Furthermore, this universal, ferritin-based antigen conjugating strategy offers significant potential for developing vaccine against diverse pathogens and diseases.

Immunogenicity of various variants of Ebola and Marburg virus glycoprotein genes in recombinant adenoviral vectors

INTRODUCTION. Marburg and Ebola viruses cause severe haemorrhagic fever in humans and primates. Currently, there are no licensed prophylactic vaccines that can simultaneously prevent the spread or reduce the severity of both diseases caused by these filoviruses. The development of effective prophylactic vaccines requires studies aimed at selecting the most immunogenic forms of protective antigens.AIM. This study aimed to evaluate humoral immune induction in animals after administration of recombinant adenoviral vectors expressing various forms of Ebola and Marburg virus glycoproteins (GPs).MATERIALS AND METHODS. Samples of recombinant human adenovirus type 5 (rAd5) were obtained using homologous recombination in Escherichia coli, growth in HEK293 cells, and purification by CsCl gradient ultracentrifugation. The resulting rAd5 samples were characterised in terms of their identity (PCR and whole-genome sequencing), the concentration of viral particles (fluorescence spectroscopy), and the concentration of infectious viral particles (TCID50 assay). Enzyme-linked immunosorbent assay (ELISA) was used to evaluate the GP-specific IgG titres in the sera of immunised mice.RESULTS. The authors constructed rAd5 samples, and each construct contained an expression cassette with a GP gene form encoding a full-length GP, a GP without the mucin-like domain, or a GP without both the glycan cap and the mucin-like domain. Each of these forms was studied using the GPs of four filoviruses, including Zaire Ebola virus, Sudan Ebola virus, Bundibugyo Ebola virus, and Marburg virus. Neither of the forms had a critical effect on the rAd5 replicative capacity. Three weeks after immunisation, the highest GP-specific IgG production was induced by the rAd5 samples encoding either the full-length GP or the GP without the mucin-like domain. The GP without both the glycan cap and the mucin-like domain was the least immunogenic antigen regardless of the filovirus species.CONCLUSIONS. The most promising constructs for the development of filovirus vaccines based on recombinant adenoviral vectors are the constructs that include the genes encoding the fulllength GP or the GP without the mucin-like domain.

Identification of feline erythrocyte antigen 6 and lack of alloimmunization to feline erythrocyte antigen 4 in cats.

New feline erythrocyte antigens (FEAs) have been described based on the presence of naturally occurring alloantibodies (NOAb), but their immunogenicity and clinical relevance are poorly understood. Describe the immunogenicity of FEA 4 after sensitizing FEA 4-negative cats lacking NOAb and characterize anti-FEA 4 alloantibodies produced, including their rate of appearance, agglutination titer, and immunoglobulin class. Nineteen healthy type A cats were blood typed for FEAs 1 to 5 to identify suitable donor-recipient pairs for FEA 4 sensitization. Four FEA 4-negative cats were transfused with FEA 4-positive red blood cells. Using a gel column technique, posttransfusion samples were screened daily for a week, weekly for a month, and monthly thereafter for anti-FEA 4 alloantibodies. Alloantibodies were not detected in the first 3 recipients despite repeated transfusions (1 and 3 additional transfusions for 2 and 1 recipients, respectively). In the 4th recipient, alloantibodies against its donor red blood cells were detected 21 days postsensitization. However, they were not directed against FEA 4, but rather against a novel FEA not yet described. The alloantibodies, named anti-FEA 6, remained detectable for >4 months after sensitization and were determined to be mostly immunoglobulin M based on sulfhydryl treatment. Feline erythrocyte antigen 4 does not appear to be immunogenic because repeated sensitization of 4 cats failed to produce detectable anti-FEA 4 alloantibodies. A new immunogenic antigen, named FEA 6, has been discovered, but additional studies are needed to document its clinical importance.

A Biomimetic Autophagosomes-Based Nanovaccine Boosts Anticancer Immunity.

Personalized cancer vaccines based on tumor cell lysates offer promise for cancer immunotherapy yet fail to elicit a robust therapeutic effect due to the weak immunogenicity of tumor antigens. Autophagosomes, obtained from pleural effusions and ascites of cancer patients, have been identified as abundant reservoirs of tumor neoantigens that exhibit heightened immunogenicity. However, their potential as personalized cancer vaccines have been constrained by suboptimal lymphatic-targeting performances and challenges in antigen-presenting cell endocytosis. Here,a reinforced biomimetic autophagosome-based (BAPs) nanovaccine generated by precisely amalgamating autophagosome-derived neoantigens and two types of adjuvants capable of targeting lymph nodes is developed to potently elicit antitumor immunity. The redox-responsive BAPs facilitate cytosolic vaccine opening within antigen-presenting cells, thereby exposing adjuvants and antigens to stimulate a strong immune response. BAPs evoke broad-spectrum T-cell responses, culminating in the effective eradication of 71.4% of established tumors. Notably, BAPs vaccination triggers enduring T-cell responses that confer robust protection, with 100% of mice shielded against tumor rechallenge and a significant reduction in tumor incidence by 87.5%. Furthermore, BAPs synergize with checkpoint blockade therapy to inhibit tumor growth in the poorly immunogenic breast cancer model. The biomimetic approach presents a powerful nanovaccine formula with high versatilityfor personalized cancer immunotherapy.

Identification of immunogenic antigens and evaluation of vaccine candidates against Clostridium perfringens

Necrotic enteritis (NE) caused by Clostridium perfringens (C. perfringens) has resulted in significant losses for the poultry industry worldwide. Currently, there is no widely promoted vaccine for NE. In this study, immunoprecipitation (IP) was employed to isolate immunogenic proteins of C. perfringens, and 118 potential candidate antigens were identified through liquid chromatography-mass spectrometry/mass spectrometry (LC–MS/MS). From these, three candidate antigen proteins were selected based on their predicted antigenicity, hydrophilicity, stability, and transmembrane signalling properties: ArcB (an ornithine aminotransferase), TmpC (a probable membrane lipoprotein), and EntB (a possible enterotoxin). These three proteins were successfully produced in large quantities using Escherichia coli (E. coli), with confirmed good solubility. Both in vitro and in vivo research demonstrated that these antigens possess strong immunogenicity, eliciting robust antigen-specific humoral and cellular immune responses in chickens and mitigating NE symptoms caused by C. perfringens. The candidate antigens identified through immunoproteomics hold potential as subunit vaccines against C. perfringens infection.

Enhancing T-cell recruitment in renal cell carcinoma with cytokine-armed adenoviruses

ABSTRACT Immunotherapy has emerged as a promising approach for cancer treatment, with oncolytic adenoviruses showing power as immunotherapeutic agents. In this study, we investigated the immunotherapeutic potential of an adenovirus construct expressing CXCL9, CXCL10, or IL-15 in clear cell renal cell carcinoma (ccRCC) tumor models. Our results demonstrated robust cytokine secretion upon viral treatment, suggesting effective transgene expression. Subsequent analysis using resistance-based transwell migration and microfluidic chip assays demonstrated increased T-cell migration in response to chemokine secretion by infected cells in both 2D and 3D cell models. Flow cytometry analysis revealed CXCR3 receptor expression across T-cell subsets, with the highest percentage found on CD8+ T-cells, underscoring their key role in immune cell migration. Alongside T-cells, we also detected NK-cells in the tumors of immunocompromised mice treated with cytokine-encoding adenoviruses. Furthermore, we identified potential immunogenic antigens that may enhance the efficacy and specificity of our armed oncolytic adenoviruses in ccRCC. Overall, our findings using ccRCC cell line, in vivo humanized mice, physiologically relevant PDCs in 2D and patient-derived organoids (PDOs) in 3D suggest that chemokine-armed adenoviruses hold promise for enhancing T-cell migration and improving immunotherapy outcomes in ccRCC. Our study contributes to the development of more effective ccRCC treatment strategies by elucidating immune cell infiltration and activation mechanisms within the tumor microenvironment (TME) and highlights the usefulness of PDOs for predicting clinical relevance and validating novel immunotherapeutic approaches. Overall, our research offers insights into the rational design and optimization of viral-based immunotherapies for ccRCC.

Long-range alternative splicing contributes to neoantigen specificity in glioblastoma.

Recent advances in neoantigen research have accelerated the development of immunotherapies for cancers, such as glioblastoma (GBM). Neoantigens resulting from genomic mutations and dysregulated alternative splicing have been studied in GBM. However, these studies have primarily focused on annotated alternatively-spliced transcripts, leaving non-annotated transcripts largely unexplored. Circular ribonucleic acids (circRNAs), abnormally regulated in tumors, are correlated with the presence of non-annotated linear transcripts with exon skipping events. But the extent to which these linear transcripts truly exist and their functions in cancer immunotherapies remain unknown. Here, we found the ubiquitous co-occurrence of circRNA biogenesis and alternative splicing across various tumor types, resulting in large amounts of long-range alternatively-spliced transcripts (LRs). By comparing tumor and healthy tissues, we identified tumor-specific LRs more abundant in GBM than in normal tissues and other tumor types. This may be attributable to the upregulation of the protein quaking in GBM, which is reported to promote circRNA biogenesis. In total, we identified 1057 specific and recurrent LRs in GBM. Through in silico translation prediction and MS-based immunopeptidome analysis, 16 major histocompatibility complex class I-associated peptides were identified as potential immunotherapy targets in GBM. This study revealed long-range alternatively-spliced transcripts specifically upregulated in GBM may serve as recurrent, immunogenic tumor-specific antigens.

Abstract PR-08: Reprogramming and selective recruitment of distinct neutrophil subpopulations restrain cancer metastasis

Abstract Neutrophils are integral to the metastatic tumor microenvironment (TME), and discrete subsets of neutrophils have been associated with pro- and anti-tumor responses. However, the composition of neutrophils in the metastatic TME and strategies to harness neutrophils for the treatment of metastatic disease remain poorly understood. Here, we studied the role of neutrophils in metastatic disease using mouse models of metastatic pancreatic ductal adenocarcinoma (PDAC). By utilizing mouse PDAC cells driven by mutant KRAS and p53 with controllable expression of ovalbumin, an immunogenic antigen (“TumorAg ON” or “TumorAg OFF”), we found that TumorAg ON PDAC engendered more than 10-fold higher recruitment of neutrophils into liver metastatic lesions compared to TumorAg OFF PDAC. RNA sequencing analysis of micro-dissected metastatic lesions showed that TumorAg ON PDAC elicited transcription of genes associated with neutrophil chemotaxis, including Cxcr2 and its ligands. Multimodal immune phenotyping and imaging mass cytometry (IMC) analysis further revealed that neutrophils within metastatic lesions consisted of CXCR2high and CXCR2low subpopulations and were spatially associated with distinct subsets of tumor cells, T cells, and myeloid cells. In both mouse models of liver and lung metastasis, small molecule inhibition of CXCR2 using SX-682 led to enrichment of CXCR2low neutrophils and reduced metastatic burden in TumorAg ON PDAC. In contrast, CXCR2 inhibition had no impact on metastatic burden in TumorAg OFF PDAC. To define the subpopulations of neutrophils in further depth, we also performed single-cell spatial transcriptomics using Xenium. Notably, CXCR2 inhibition in TumorAg ON PDAC, but not in TumorAg OFF, led to enrichment of neutrophil subsets that expressed higher levels of Mpo, Nos2, and Ly6g and lower levels of Cxcr2 and Siglecf into metastatic lesions. In this setting, depletion of neutrophils using anti-Ly6G antibodies worsened metastatic burden, highlighting anti-tumor properties of these neutrophil subsets in the presence of antigenic recognition. Indeed, in a highly immune-resistant model of PDAC, 6419c5, the use of tumor-targeting listeria vaccine CRS-207 along with CXCR2 inhibition significantly reduced metastatic burden, whereas CXCR2 inhibitor or CRS-207 alone had no impact. To extend the clinical relevance of these observations, we analyzed serial tissue biopsies collected from patients with metastatic PDAC in the liver treated with immunotherapy regimen incorporating CRS-207 (NCT03190265). Consistent with our mouse model results, IMC analysis revealed increased proportion of MPOhigh NOS2high neutrophils upon treatment, suggesting that induction of tumor antigen response results in an effective remodeling of the neutrophil compartment . Taken together, our results show that neutrophils may acquire anti-tumor properties under appropriate inflammatory conditions and that distinct subpopulations of neutrophils may be leveraged for the treatment of metastatic disease. Citation Format: Jae W Lee, Diana Caroline Vargas Carvajal, Yeonju Cho, Sarah M Shin, Erin M Coyne, Alexei Hernandez, Courtney D Cannon, Xuan Yuan, Zhehao Zhang, Nicole E Gross, Soren Charmsaz, Daniel H Shu, Katherine M Bever, Dung T Le, Luciane T Kagohara, Elizabeth M Jaffee, Won Jin Ho. Reprogramming and selective recruitment of distinct neutrophil subpopulations restrain cancer metastasis [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr PR-08.