Multiple Antigenic Epitopes Research Articles

Bioinformatics analysis of the RNA binding protein DDX39 of Toxoplasma gondii

To analyze the RNA binding protein of Toxoplasma gondii (TgDDX39) using bioinformatics technology, and to evaluate the immunogenicity of TgDDX39, so as to provide insights into development of toxoplasmosis vaccines. The amino acid sequences of TgDDX39 were retrieved from the ToxoDB database, and the physicochemical properties, transmembrane structure domain, signal peptide sites, post-translational modification sites, coils, secondary and tertiary structures, hydrophobicity, and antigenic epitopes of the TgDDX39 protein were predicted using online bioinformatics tools, incluiding ProtParam, TMHMM 2.0, SignalP 5.0, NetPhos 3.1, COILS, SOPMA, Phyre2, ProtScale, ABCpred, SYFPEITHI and DNA-STAR. TgDDX39 protein was predicted to be an unstable hydrophilic protein with the molecular formula of C2173H3458N598O661S18, which contained 434 amino acids and had an estimated molecular weight of 49.1 kDa and a theoretical isoelectric point of 5.55. The protein was predicted to have an extremely low possibility of signal peptides, without transmembrane regions, and contain 27 phosphorylation sites. The β turn and random coils accounted for 39.63% of the secondary structure of the TgDDX39 protein, and a coiled helix tended to produce in one site. In addition, the TgDDX39 protein contained multiple B and T cell antigenic epitopes. Bioinformatics analyses predict that TgDDX39 protein has high immunogenicity and contains multiple antigenic epitopes. TgDDX39 protein is a potential candidate antigen for vaccine development.

A tactical nanomissile mobilizing antitumor immunity enables neoadjuvant chemo-immunotherapy to minimize postsurgical tumor metastasis and recurrence.

Neoadjuvant chemotherapy has become an indispensable weapon against high-risk resectable cancers, which benefits from tumor downstaging. However, the utility of chemotherapeutics alone as a neoadjuvant agent is incapable of generating durable therapeutic benefits to prevent postsurgical tumor metastasis and recurrence. Herein, a tactical nanomissile (TALE), equipped with a guidance system (PD-L1 monoclonal antibody), ammunition (mitoxantrone, Mit), and projectile bodies (tertiary amines modified azobenzene derivatives), is designed as a neoadjuvant chemo-immunotherapy setting, which aims at targeting tumor cells, and fast-releasing Mit owing to the intracellular azoreductase, thereby inducing immunogenic tumor cells death, and forming an in situ tumor vaccine containing damage-associated molecular patterns and multiple tumor antigen epitopes to mobilize the immune system. The formed in situ tumor vaccine can recruit and activate antigen-presenting cells, and ultimately increase the infiltration of CD8+ T cells while reversing the immunosuppression microenvironment. Moreover, this approach provokes a robust systemic immune response and immunological memory, as evidenced by preventing 83.3% of mice from postsurgical metastasis or recurrence in the B16-F10 tumor mouse model. Collectively, our results highlight the potential of TALE as a neoadjuvant chemo-immunotherapy paradigm that can not only debulk tumors but generate a long-term immunosurveillance to maximize the durable benefits of neoadjuvant chemotherapy.

Optimized mobilization of MHC class I- and II- restricted immunity by dendritic cell vaccine potentiates cancer therapy.

Background: The participation of major histocompatibility complex (MHC) in antigen presentation shapes both the breadth and magnitude of specific T cell response. Dendritic cells (DCs) activated with nucleic acid or protein that encodes/incorporates multiple antigenic epitopes elicit MHC class I- and II- biased immunity, respectively. Studies demonstrate that an elevated MHC class I-directed CD8+ cytotoxicity T lymphocyte (CTL) response is able to provide survival benefits to patient with malignant tumor. However, a fully effective cancer therapy must elicit a diverse repertoire of both CD4+ and CD8+ T cell responses, raising demands on a multifaceted activation of the MHC system. Current therapeutic strategies usually lack an orchestrated mobilization of the MHC class I and II responses. Vaccines with little synergistic effect or unmanageable elicitation of the CD4+ and CD8+ T cell immunity usually fail to induce a potent and durable anti-tumor protection.Methods: Here, cationic nanoemulsions (CNEs) complexed with full-length tumor model antigen ovalbumin (OVA) in the form of mRNA or protein were constructed and used as two antigenic platforms to prepare DCs vaccines with tailored MHC participation (i.e., mRNA-DCs and protein-DCs). In exploring a vaccine regimen with optimal tumor suppressing effect, the mixing ratio of mRNA-DCs and protein-DCs was manipulated.Results: Therapeutic DCs vaccines involving both antigenic platforms induced better anti-tumor immunity in murine E.G7-OVA lymphoma model and B16-OVA melanoma model, which can be further augmented upon a meticulous reallocation of the MHC class I and II responses.Conclusion: This work indicated that a simultaneous and coordinated mobilization of the MHC-restricted immunity might potentiate cancer therapy.

Vaccination by Two DerG LEAPS Conjugates Incorporating Distinct Proteoglycan (PG, Aggrecan) Epitopes Provides Therapy by Different Immune Mechanisms in a Mouse Model of Rheumatoid Arthritis.

Rheumatoid arthritis (RA) can be initiated and driven by immune responses to multiple antigenic epitopes including those in cartilage proteoglycan (PG, aggrecan) and type II collagen. RA is driven by T helper 1 (Th1) or Th17 pro-inflammatory T cell responses. LEAPS (Ligand Epitope Antigen Presentation System) DerG peptide conjugate vaccines were prepared using epitopes from PG that elicit immune responses in RA patients: epitope PG70 (DerG-PG70, also designated CEL-4000) and the citrullinated form of another epitope (PG275Cit). The LEAPS peptides were administered alone or together in Seppic ISA51vg adjuvant to mice with PG G1 domain-induced arthritis (GIA), a mouse model of RA. Each of these LEAPS peptides and the combination modulated the inflammatory response and stopped the progression of arthritis in the GIA mouse model. Despite having a therapeutic effect, the DerG-PG275Cit vaccine did not elicit significant antibody responses, whereas DerG-PG70 (alone or with DerG-PG275Cit) induced both therapy and antibodies. Spleen T cells from GIA mice, vaccinated with the DerG LEAPS peptides, preferentially produced anti-inflammatory (IL-4 and IL-10) rather than pro-inflammatory (IFN-γ or IL-17) cytokines in culture. Similarly, cytokines secreted by CD4+ cells of unvaccinated GIA mice, differentiated in vitro to Th2 cells and treated with either or both DerG vaccine peptides, exhibited an anti-inflammatory (IL-4, IL-10) profile. These results suggest that the two peptides elicit different therapeutic immune responses by the immunomodulation of disease-promoting pro-inflammatory responses and that the combination of the two LEAPS conjugates may provide broader epitope coverage and, in some cases, greater efficacy than either conjugate alone.

High neutralizing potency of swine glyco-humanized polyclonal antibodies against SARS-CoV-2.

Heterologous polyclonal antibodies might represent an alternative to the use of convalescent plasma or monoclonal antibodies (mAbs) in coronavirus disease (COVID‐19) by targeting multiple antigen epitopes. However, heterologous antibodies trigger human natural xenogeneic antibody responses particularly directed against animal‐type carbohydrates, mainly the N‐glycolyl form of the neuraminic acid (Neu5Gc) and the α1,3‐galactose, potentially leading to serum sickness or allergy. Here, we immunized cytidine monophosphate‐N‐acetylneuraminic acid hydroxylase and α1,3‐galactosyl‐transferase (GGTA1) double KO pigs with the Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) spike receptor binding domain to produce glyco‐humanized polyclonal neutralizing antibodies lacking Neu5Gc and α1,3‐galactose epitopes. Animals rapidly developed a hyperimmune response with anti‐SARS‐CoV‐2 end‐titers binding dilutions over one to a million and end‐titers neutralizing dilutions of 1:10 000. The IgG fraction purified and formulated following clinical Good Manufacturing Practices, named XAV‐19, neutralized spike/angiotensin converting enzyme‐2 interaction at a concentration <1 μg/mL, and inhibited infection of human cells by SARS‐CoV‐2 in cytopathic assays. We also found that pig GH‐pAb Fc domains fail to interact with human Fc receptors, thereby avoiding macrophage‐dependent exacerbated inflammatory responses and a possible antibody‐dependent enhancement. These data and the accumulating safety advantages of using GH‐pAbs in humans warrant clinical assessment of XAV‐19 against COVID‐19.

Argentinian small ruminant lentivirus (SRLV) p55gag antigen fused to maltose binding protein to use in SRLV serological confirmatory diagnosis

The complete gag gene from small ruminant lentiviruses (SRLV) encodes for a polyprotein of 55 kDa, known as p55gag. p55gag presents multiple antigenic epitopes, which can be recognized by antibodies, increasing the opportunity to detect SRLV-positive animals. Therefore, this polyprotein is considered an excellent candidate to use in diagnostic tests to detect antibodies against SRLV. Different studies have suggested that the selection of the recombinant antigen, which must be representative of the virus strains circulating in the test population, is crucial to avoid false negative results. Thus, the use of proteins from different viral strains isolated from goats or sheep of a given region or country may be a useful strategy to increase the ability to detect SRLV-infected animals. In the present study, the pMAL-p5X vector was used to express and purify p55gag (now called rp55gag for recombinant polyprotein 55 gag). The cloned gene was inserted downstream from the malE gene of Escherichia coli, which encodes a maltose-binding protein (MBP), resulting in the expression of an MBP fusion protein. The complete gag gene was amplified by RT-PCR. Finally, after digestion, the product was cloned into the pMAL-p5X vector and used to transform E. coli ER2325 cells. After the purification of MBP-rp55gag by affinity chromatography, the eluted fraction was observed by SDS-PAGE and Western Blot (WB). The WB was carried out with 85 serum samples from small ruminants previously analysed and compared by two commercial ELISAs. The results show that 76 of the serum samples were concordant with those by both ELISAs. Regarding the other nine serum samples, which showed discordant results between both ELISAs, were positive by WB. The results thus show that the rp55gag could be considered as an antigen in a confirmatory diagnostic assay to detect SRLV by WB. For this purpose, a future study with a high number of sera to determine the test specificity and sensitivity, using the p55gag of the circulating strain in Argentina will be necessary.

Immunogenicity of a Virus-Like-Particle Vaccine Containing Multiple Antigenic Epitopes of Toxoplasma gondii Against Acute and Chronic Toxoplasmosis in Mice.

There is no effective protective vaccine against human toxoplasmosis, which is a potential threat to nearly a third of the world population. Vaccines based on virus-like particles (VLPs) have been highly successful in humans for many years, but have rarely been applied against Toxoplasma gondii infection. In this study, we inserted a B cell epitope (SAG182−102 or SAG1301−320), a CD8+ cell epitope (HF10 or ROP7), and a CD4+ cell epitope (AS15) of T. gondii into a truncated HBcΔ(amino acids1–149) particle to construct four chimeric VLP vaccine formulations, i.e., HBcΔH82, HBcΔH301, HBcΔ R82, and HBcΔ R301. When these chimeric HBc particles were expressed in Escherichia coli, they showed icosahedral morphology similar to that of the original VLPs and were evaluated as vaccine formulations against acute and chronic toxoplasmosis in a mouse model (BALB/c mice (H-2d). All these chimeric HBc VLPs induced strong humoral and cellular immune responses with high IgG antibody titers and interferon(IFN)-γ production. Only the mice immunized with HBcΔH82 showed prolonged survival time (15.6 ± 3.8 vs. 5.6 ± 0.8 days) against acute infection with RH tachyzoites and decrease in brain parasite load (1,454 ± 239 vs. 2,091 ± 263) against chronic infection with Prugniuad cysts, as compared to the findings for the control group. These findings suggest that HBc VLPs would act as an effective carrier for delivering effective multiple antigenic epitopes and would be beneficial for developing a safe and long-acting vaccine against toxoplasmosis.

A recombinant multi-epitope peptide vaccine based on MOMP and CPSIT_p6 protein protects against Chlamydia psittaci lung infection.

Chlamydia psittaci is an obligate intracellular pathogen with a broad host range that can lead to severe infectious disease by transferring from birds to humans. Vaccination has been considered the best way to prevent chlamydial infection; nevertheless, there is currently still no commercially available vaccine that can inhibit the spread of C. psittaci. In previous study, major outer membrane protein (MOMP) of C. psittaci was confirmed to be an appropriate candidate antigen for limiting C. psittaci respiratory infections in a murine model, and plasmid-encoded CPSIT_p6 also has functions similar to those of MOMP in our study. Therefore, according to bioinformatics analysis, we developed a recombinant peptide containing multiple antigenic epitopes from MOMP (24-32, 262-272) and CPSIT_p6 protein (109-119, 173-181) and evaluated the efficacy of peptide immunization. BALB/c mice were inoculated intraperitoneally with the recombinant multi-epitope antigens three times at 2-week intervals and subsequently intranasally infected with C. psittaci. We found that the recombinant multi-epitope antigens induced strong humoral and Th1 cellular immune responses by producing meaningfully high levels of antigen-specific antibodies, interferon-gamma (IFN-γ), or interleukin-2 (IL-2). Vaccination significantly reduced the bacterial burden and the degree of inflammation in the infected lungs and led to lower levels of IFN-γ and IL-6. Furthermore, adoptive transfer of CD4+ splenocytes harvested from the vaccinated mice produced a significantly lower chlamydial load, indicating the importance of the cellular immune response. Therefore, the recombinant multi-epitope antigens may provide the basis for a new peptide-based vaccine against C. psittaci infection.

Chitosan Microsphere Used as an Effective System to Deliver a Linked Antigenic Peptides Vaccine Protect Mice Against Acute and Chronic Toxoplasmosis.

Multiple antigenic peptide (MAP) vaccines have advantages over traditional Toxoplasma gondii vaccines, but are more susceptible to enzymatic degradation. As an effective delivery system, chitosan microspheres (CS) can overcome this obstacle and act as a natural adjuvant to promote T helper 1 (Th1) cellular immune responses. In this study, we use chitosan microparticles to deliver multiple antigenic epitopes from GRA10 (G10E), containing three dominant epitopes. When G10E was entrapped within chitosan microparticles (G10E-CS), adequate peptides for eliciting immune response were loaded in the microsphere core and this complex released G10E peptides stably. The efficiency of G10E-CS was detected both in vitro, via cell culture, and through in vivo mouse immunization. In vitro, G10E-CS activated Dendritic Cells (DC) and T lymphocytes by upregulating the secretion of costimulatory molecules (CD40 and CD86). In vivo, Th1 biased cellular and humoral immune responses were activated in mice vaccinated with G10E-CS, accompanied by significantly increased production of IFN-γ, IL-2, and IgG, and decreases in IL-4, IL-10, and IgG1. Immunization with G10E-CS conferred significant protection with prolonged survival in mice model of acute toxoplasmosis and statistically significant decreases in cyst burden in murine chronic toxoplasmosis. The results from this study indicate that chitosan microspheres used as an effective system to deliver a linked antigenic peptides is a promising strategy for the development of efficient vaccine against T. gondii.

T cells directed against different myelin antigen epitopes cooperate to induce autoimmune encephalomyelitis in mice

Abstract Multiple Sclerosis (MS) is the most common demyelinating autoimmune disease of the central nervous system (CNS). Important insights have emerged into the pathogenic mechanisms that drive the inflammatory events and demyelination in MS, however, much less is known about the events initiating this disease. The murine model of MS, experimental autoimmune encephalomyelitis (EAE), is usually induced through injection with a high dose of single immunodominant peptides found on the myelin sheath of the CNS. Low doses of single peptide do not induce EAE or result in very low disease incidence. In individual MS patients, autoimmune T cell-reactivity is usually directed against multiple myelin antigen epitopes and fluctuates significantly over the course of disease. Thus, we hypothesize that MS is triggered by the emergence of autoreactive T cells directed against multiple myelin epitopes, which together synergize to induce the disease. To test this concept in an animal model of EAE, we explored the effect of induction of EAE using combinations of low dose peptides akin to a “multiple hit” mechanism implicated in other disease conditions. We found that EAE can be induced through the immunization of mice with a combination of low dose myelin peptides from different myelin proteins, which individually are suboptimal to induce disease. The disease observed after multi-peptide immunization is comparable or more severe than with optimal doses of peptide traditionally used to induce EAE. This research provides new insights into the potential mechanisms underlying the induction of MS and could lead to novel approaches for immunotherapy.

71 - An in silico designed dosimetric autologous living vaccine consisting of with Multiple Wilms' Tumor 1 WT1-ConSynthetic–Restricted Peptide mimotopic Epitopes RMFPNAPYLP pulsed dendritic cells on a personalized Active Network analysis for asymptomatic or minimally symptomatic metastatic Pancreatic Cancer

First described in the 1970s, dendritic cells (DC) are currently subjects of intense investigation to exploit their unique antigen-presenting and immunoregulatory capacities. In cancer, DC show promise to elicit or amplify immune responses directed against cancer cells by activating natural killer (NK) cells and tumor antigen-specific T cells. Wilms' tumor 1 (WT1) protein is a tumor-associated antigen that is expressed in a majority of cancer types and has been designated as an antigen of major interest to be targeted in clinical cancer immunotherapy trials. DendriGeneaTM®-PAC is an in silica designed dosimetric dose calculated autologous living vaccine consisting of with Multiple Wilms' Tumor 1 WT1-ConSynthetic–Restricted Peptide mimotopic Epitopes RMFPNAPYLP pulsed dendritic cells on a personalized Active Network analysis of asymptomatic or minimally symptomatic metastatic Pancreatic Cancer. In this scientific work we describe the generation, cryopreservation, and thawing of clinical grade autologous monocyte-derived DC vaccines that are loaded with WT1 by messenger RNA (mRNA) electroporation. This in-house-developed transfection method gives rise to presentation of multiple antigen epitopes and can be used for all patients without restriction of human leukocyte antigen (HLA) type. We introduced a probabilistic treatment planning approach that prospectively incorporates respiratory-induced motion in the treatment plan optimization. The aim of this study was to determine the potential dosimetric benefit by comparing this approach to the use of an internal target volume (ITV) on an artificial three-dimensional (3D) culture system that mimics the tumor microenvironment in vitro is an essential tool for investigating the cross-talk between immune and cancer cells in a 3D culture system using an electrospun poly(ε-caprolactone) (PCL) nanofibrous scaffold (NFS).

Generation and Cryopreservation of Clinical Grade Wilms' Tumor 1 mRNA-Loaded Dendritic Cell Vaccines for Cancer Immunotherapy.

First described in the 1970s, dendritic cells (DC) are currently subjects of intense investigation to exploit their unique antigen-presenting and immunoregulatory capacities. In cancer, DC show promise to elicit or amplify immune responses directed against cancer cells by activating natural killer (NK) cells and tumor antigen-specific T cells. Wilms' tumor 1 (WT1) protein is a tumor-associated antigen that is expressed in a majority of cancer types and has been designated as an antigen of major interest to be targeted in clinical cancer immunotherapy trials. In this chapter, we describe the generation, cryopreservation, and thawing of clinical grade autologous monocyte-derived DC vaccines that are loaded with WT1 by messenger RNA (mRNA) electroporation. This in-house-developed transfection method gives rise to presentation of multiple antigen epitopes and can be used for all patients without restriction of human leukocyte antigen (HLA) type.

Long-term survival correlates with immunological responses in renal cell carcinoma patients treated with mRNA-based immunotherapy

ABSTRACTRenal cell carcinoma (RCC) is an immunogenic tumor for which immunotherapeutic approaches could be associated with clinically relevant responses. It was recently shown, that induction of T-cell responses against multiple tumor-associated antigen (TAA) epitopes results in prolonged overall survival in RCC patients. In 2003–2005, we performed a phase I/II trial testing an mRNA-based vaccine formulation consisting of a mixture of in vitro transcribed RNA coding for six different TAAs (MUC1, CEA, Her2/neu, telomerase, survivin, MAGE-A1) in 30 metastatic RCC (mRCC) patients. In the first 14 patients, vaccinations were applied i.d. on days 0, 14, 28, and 42. In the consecutive 16 patients, an intensified protocol consisting of i.d. injections (daily on days 0–3, 7–10, 28, and 42) was used. After the respective induction periods, patients in both cohorts were vaccinated monthly until tumor progression. At survival update performed in July 2015, one of the 30 patients was still alive. One patient was lost to follow-up. Median survival of 24.5 mo (all patients) and 89 mo (favorable risk patients) exceeded predicted survival according to Memorial Sloan Kettering Cancer Center (MSKCC) risk score. Impressively, long-term survivors displayed immunological responses to the applied antigens while vice versa no patient without detectable immune response had survived more than 33 mo. The current survival update shows a clear correlation between survival and immunological responses to TAAs encoded by the naked mRNA vaccine. This is one of the first vaccination studies and the only RNA trial that reports on safety and efficacy after a follow-up of more than 10 y.

DNA vaccine cocktail expressing genotype A and C HBV surface and consensus core antigens generates robust cytotoxic and antibody responses in mice and Rhesus macaques

There are well over a quarter of a billion chronic hepatitis B virus (HBV) carriers across the globe. Most carriers are at high risk for development of liver cirrhosis and subsequent progression to hepatocellular carcinoma. It is therefore imperative to develop new approaches for immunotherapy against this infection. Antibodies and cytotoxic T cells to different HBV antigens are believed to be important for reducing viral load and clearing HBV-infected cells from the liver. Some of the major challenges facing current vaccine candidates have been their inability to induce both humoral and cellular immunity to multiple antigenic targets and the induction of potent immune responses against the major genotypes of HBV. In this study, highly optimized synthetic DNA plasmids against the HBV consensus core (HBc) and surface (HBs) antigens genotypes A and C were developed and evaluated for their immune potential. These plasmids, which encode the most prevalent genotypes of the virus, were observed to individually induce binding antibodies to HBs antigens and drove robust cell-mediated immunity in animal models. Similar responses to both HBc and HBs antigens were observed when mice and non-human primates were inoculated with the HBc-HBs cocktails. In addition to the cytotoxic T lymphocyte activities exhibited by the immunized mice, the vaccine-induced responses were broadly distributed across multiple antigenic epitopes. These elements are believed to be important to develop an effective therapeutic vaccine. These data support further evaluation of multivalent synthetic plasmids as therapeutic HBV vaccines.

Lipid-coated PLGA nanoparticles carrying multiple antigenic epitopes for efficient induction of anti-tumor immunity

Lipid-coated PLGA nanoparticles carrying multiple antigenic epitopes for efficient induction of anti-tumor immunity

Bioinformatics Analysis and Characteristics of UL17 Protein Encoded by the UL17 Gene from Duck Enteritis Virus

Previous studies indicate that the UL17 protein and its homology play similar roles in viral DNA cleavage and packaging of herpesviruses. However, there is no report on the UL17 gene product of DEV. Here in this article we used various bioinformatics softwares and online web servers to analyze the basic properties of the DEV UL17 protein. The results showed that the DEV UL17 protein was 75.94298 kDa, consisting of 684 amino acids. It had multiple motif sites, phosphorylation sites and antigenic epitopes. There were no predicted signal peptide sites or transmembrane regions in DEV UL17 protein. The results of secondary structure and teriary structure were exhibited in the pictures in this article. These properties of the DEV UL17 protein provide a prerequisite for further functional analysis of this gene.

Challenges facing lipoarabinomannan urine antigen tests for diagnosing HIV-associated tuberculosis

Challenges facing lipoarabinomannan urine antigen tests for diagnosing HIV-associated tuberculosis

Abstract LB-135: A pilot study of peptide-based vaccines in combination with poly ICLC in patients with WHO grade 2 low-grade glioma

Abstract Introduction: Adult patients with WHO grade 2 low-grade glioma (LGG) have a significant risk of tumor progression despite treatment with surgery or surgery followed by radiation therapy (RT) and /or chemotherapy, and most patients eventually die of the disease. High-risk subsets of these LGG patients display astrocytoma or oligoastrocytoma histology plus any one of the following conditions: 1) age ≥40 with any extent resection; 2) age 18-39 with incomplete resection; or 3) age 18-39 with neurosurgeon-defined gross total resection with tumor size ≥ 4 cm in diameter. These patients have as high as an 89% risk of recurrence by 5 years following surgery. Methods: Based on encouraging data from a phase I vaccine study targeting multiple glioma-associated antigen (GAA) epitopes in adult high-grade glioma (HGG) patients, we initiated a bi-institutional pilot study of subcutaneous vaccinations of subcutaneous vaccinations with synthetic peptides for GAA epitopes emulsified in Montanide-ISA-51 every 3 weeks for 8 courses, and intramuscular administration of poly-ICLC in HLA-A2+ patients with: newly diagnosed high-risk LGG without prior RT (Cohort 1); newly diagnosed high-risk LGG with prior RT (Cohort 2), or recurrent LGG (Cohort 3). Primary endpoints were safety and CD8+ T-cell responses against vaccine-targeted GAAs, assessed by Enzyme-Linked Immuno-SPOT (ELISPOT) assays. Treatment response was evaluated clinically and by MR imaging. Targeted GAAs were EphA2, interleukin (IL)-13 receptor-α2, survivin, and WT1. As these GAAs are expressed not only in a subset of LGG cells but even at higher levels in HGG cells, our vaccine approach may offer both immunotherapeutic and immunoprophylactic potential to reduce the risk of tumor recurrence. Results: To date, 13, 1 and 10 patients have been enrolled in Cohorts 1, 2 and 3, respectively. No dose-limiting non-CNS toxicity has been encountered except for one case with Grade 3 fever (Cohort 1). ELISPOT assays, completed in 7 and 1 patients in Cohorts 1 and 2, respectively, demonstrated robust and sustained interferon (IFN)-γ (type-1) responses against at least 3 of the GAA epitopes in all cases, while IL-5 (type-2) responses were absent or transient in all cases. The magnitude of the IFN-γ ELISPOT responses in the current study was significantly higher than that observed in our previous phase I/II study in HGG patients (Okada H et al. 2011). Although evaluation of progression-free survival would require a longer observation period, among 9, 1 and 7 patients who completed the 8 vaccinations spanning 24 weeks, 6, 1 and 3 patients in Cohorts 1, 2 and 3, respectively, are currently with stable disease. Conclusion: Our preliminary results demonstrate that the regimen in these patients is well tolerated, and induces robust type-1 anti-GAA T-cell responses. These data suggest that patients with LGG are suitable for vaccine therapy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-135. doi:1538-7445.AM2012-LB-135

Clinical development of MVA-based therapeutic cancer vaccines

Tumor-associated antigens (TAAs) have been formulated into vaccines that, combined with adjuvants, cytokines or other strategies to boost the immune response, are now in clinical development. Both humoral and cellular immune responses to TAAs have been generated using these vaccines. This approach relies on the patient’s own immune system generating an effective anti-tumor immune response. The advantage of this over therapy with monoclonal antibodies for the treatment of cancer is that multiple antigenic epitopes can be involved and the immune system is able to adapt to the most effective antigenic specificity for tumor growth control and rejection. In this article, we describe the clinical use of vaccinia virus, in particular modified vaccinia virus Ankara (MVA), to express TAAs in vivo and to stimulate an effective immune response to the cancer antigens.

RNA-transfected CD40-activated B cells induce functional T-cell responses against viral and tumor antigen targets: implications for pediatric immunotherapy

AbstractVaccination with antigen-presenting cells (APCs) engineered to mimic mechanisms of immune stimulation represents a promising approach for cancer immunotherapy. Dendritic cell vaccines have entered phase 3 testing in adult malignancies, but such vaccines in children have been limited. We demonstrate that CD40-activated B cells (CD40-B) transfected with RNA may serve as an alternative vaccine that can be generated from small blood volumes regardless of patient age. CD40-B from pediatric patients are efficient APCs and can be loaded with RNA as an antigenic payload, permitting simultaneous targeting of multiple antigenic epitopes without the necessity of HLA matching. For viral and tumor antigens, CD40-B/RNA technology induced cytotoxic T lymphocytes (CTLs) from adults and children, which could be identified with peptide/major histocompatibility complex (MHC) tetramers. These CTLs secreted interferon-γ (IFN-γ) and killed targets in an MHC-restricted fashion. For pooled neuroblastoma RNA and autologous neuroblastoma RNA, CTLs that lysed neuroblastoma cell lines, including CTLs specific against the widely expressed tumor-antigen survivin, were generated. These findings support a novel platform for tumor-specific vaccine or adoptive immunotherapies in pediatric malignancies.