Safety and immunogenicity of a synthetic nanoparticle-based, T cell priming peptide vaccine against dengue in healthy adults in Switzerland: a double-blind, randomized, vehicle-controlled, phase 1 study.

BACKGROUND: Vaccines that minimize the risk of vaccine-induced antibody-dependent enhancement and severe dengue are needed to address the global health threat posed by dengue. This study assessed the safety and immunogenicity of a gold nanoparticle (GNP)-based, multi-valent, synthetic peptide dengue vaccine candidate (PepGNP-Dengue), designed to provide protective CD8+ T cell immunity, without inducing antibodies. METHODS: In this randomized, double-blind, vehicle-controlled, phase 1 trial (NCT04935801), healthy naïve individuals aged 18-45 years recruited at the Centre for primary care and public health, Lausanne, Switzerland, were randomly assigned to receive PepGNP-Dengue or comparator (GNP without peptides [vehicle-GNP]). Randomization was stratified into four groups (low dose [LD] and high dose [HD]), allocation was double-blind from participants and investigators. Two doses were administered by intradermal microneedle injection 21 days apart. Primary outcome was safety, secondary outcome immunogenicity. Analysis was by intention-to-treat for safety, intention-to-treat and per protocol for immunogenicity. FINDINGS: 26 participants were enrolled (August-September 2021) to receive PepGNP-Dengue (LD or HD, n = 10 each) or vehicle-GNP (LD or HD, n = 3 each). No vaccine-related serious adverse events occurred. Most (90%) related adverse events were mild; injection site pain and transient discoloration were most frequently reported. Injection site erythema occurred in 58% of participants. As expected, PepGNP-Dengue did not elicit anti-DENV antibodies of significance. Significant increases were observed in specific CD8+ T cells and dengue dextramer+ memory cell subsets in the LD PepGNP-Dengue but not in the HD PepGNP-Dengue or vehicle-GNP groups, specifically PepGNP-activated CD137+CD69+CD8+ T cells (day 90, +0.0318%, 95% CI: 0.0088-0.1723, p = 0.046), differentiated effector memory (TemRA) and central memory (Tcm) CD8+ T cells (day 35, +0.8/105 CD8+, 95% CI: 0.19-5.13, p = 0.014 and +1.34/105 CD8+, 95% CI: 0.1-7.34, p = 0.024, respectively). INTERPRETATION: Results provide proof of concept that a synthetic nanoparticle-based peptide vaccine can successfully induce virus-specific CD8+ T cells. The favourable safety profile and cellular responses observed support further development of PepGNP-Dengue. FUNDING: Emergex Vaccines Holding Limited.

P. falciparum and P. vivax Orthologous Coiled-Coil Candidates for a Potential Cross-Protective Vaccine.

Over the last four decades, significant efforts have been invested to develop vaccines against malaria. Although most efforts are focused on the development of P. falciparum vaccines, the current availability of the parasite genomes, bioinformatics tools, and high throughput systems for both recombinant and synthetic antigen production have helped to accelerate vaccine development against the P. vivax parasite. We have previously in silico identified several P. falciparum and P. vivax proteins containing α-helical coiled-coil motifs that represent novel putative antigens for vaccine development since they are highly immunogenic and have been associated with protection in many in vitro functional assays. Here, we selected five pairs of P. falciparum and P. vivax orthologous peptides to assess their sero-reactivity using plasma samples collected in P. falciparum- endemic African countries. Pf-Pv cross-reactivity was also investigated. The pairs Pf27/Pv27, Pf43/Pv43, and Pf45/Pv45 resulted to be the most promising candidates for a cross-protective vaccine because they showed a high degree of recognition in direct and competition ELISA assays and cross-reactivity with their respective ortholog. The recognition of P. vivax peptides by plasma of P. falciparum infected individuals indicates the existence of a high degree of cross-reactivity between these two Plasmodium species. The design of longer polypeptides combining these epitopes will allow the assessment of their immunogenicity and protective efficacy in animal models.

Results of the phase I open label clinical trial SAKK 06/14 assessing safety of intravesical instillation of VPM1002BC, a recombinant mycobacterium Bacillus Calmette Guérin (BCG), in patients with non-muscle invasive bladder cancer and previous failure of conventional BCG therapy.

Background: VPM1002BC is a modified mycobacterium Bacillus Calmette Guérin (BCG) for the treatment of non-muscle invasive bladder cancer (NMIBC). The genetic modifications are expected to result in better immunogenicity and less side effects. We report on patient safety and immunology of the first intravesical application of VPM1002BC in human. Methods: Six patients with BCG failure received a treatment of 6 weekly instillations with VPM1002BC. Patients were monitored for adverse events (AE), excretion of VPM1002BC and cytokines, respectively. Results: No DLT (dose limiting toxicity) occurred during the DLT-period. No grade ≥3 AEs occurred. Excretion of VPM1002BC in the urine was limited to less than 24 hours. Plasma levels of TNFα significantly increased after treatment and blood-derived CD4+ T cells stimulated with PPD demonstrated significantly increased intracellular GM-CSF and IFN expression. Conclusion: The intravesical application of VPM1002BC is safe and well tolerated by patients and results in a potential Th1 weighted immune response.

Epitope Mapping and Fine Specificity of Human T and B Cell Responses for Novel Candidate Blood-Stage Malaria Vaccine P27A.

P27A is a novel synthetic malaria vaccine candidate derived from the blood stage Plasmodium falciparum protein Trophozoite Exported Protein 1 (TEX1/PFF0165c). In phase 1a/1b clinical trials in malaria unexposed adults in Switzerland and in malaria pre-exposed adults in Tanzania, P27A formulated with Alhydrogel and GLA-SE adjuvants induced antigen-specific antibodies and T-cell activity. The GLA-SE adjuvant induced significantly stronger humoral responses than the Alhydrogel adjuvant. Groups of pre-exposed and unexposed subjects received identical vaccine formulations, which supported the comparison of the cellular and humoral response to P27A in terms of fine specificity and affinity for populations and adjuvants. Globally, fine specificity of the T and B cell responses exhibited preferred recognized sequences and did not highlight major differences between adjuvants or populations. Affinity of anti-P27A antibodies was around 10-8 M in all groups. Pre-exposed volunteers presented anti-P27A with higher affinity than unexposed volunteers. Increasing the dose of GLA-SE from 2.5 to 5 µg in pre-exposed volunteers improved anti-P27A affinity and decreased the number of recognized epitopes. These results indicate a higher maturation of the humoral response in pre-exposed volunteers, particularly when immunized with P27A formulated with 5 µg GLA-SE.

Safety and immunogenicity of a chimpanzee adenovirus-vectored Ebola vaccine in healthy adults: a randomised, double-blind, placebo-controlled, dose-finding, phase 1/2a study.

BACKGROUND: The ongoing Ebola outbreak led to accelerated efforts to test vaccine candidates. On the basis of a request by WHO, we aimed to assess the safety and immunogenicity of the monovalent, recombinant, chimpanzee adenovirus type-3 vector-based Ebola Zaire vaccine (ChAd3-EBO-Z). METHODS: We did this randomised, double-blind, placebo-controlled, dose-finding, phase 1/2a trial at the Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland. Participants (aged 18-65 years) were randomly assigned (2:2:1), via two computer-generated randomisation lists for individuals potentially deployed in endemic areas and those not deployed, to receive a single intramuscular dose of high-dose vaccine (5 × 10(10) viral particles), low-dose vaccine (2·5 × 10(10) viral particles), or placebo. Deployed participants were allocated to only the vaccine groups. Group allocation was concealed from non-deployed participants, investigators, and outcome assessors. The safety evaluation was not masked for potentially deployed participants, who were therefore not included in the safety analysis for comparison between the vaccine doses and placebo, but were pooled with the non-deployed group to compare immunogenicity. The main objectives were safety and immunogenicity of ChAd3-EBO-Z. We did analysis by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT02289027. FINDINGS: Between Oct 24, 2014, and June 22, 2015, we randomly assigned 120 participants, of whom 18 (15%) were potentially deployed and 102 (85%) were non-deployed, to receive high-dose vaccine (n=49), low-dose vaccine (n=51), or placebo (n=20). Participants were followed up for 6 months. No vaccine-related serious adverse events were reported. We recorded local adverse events in 30 (75%) of 40 participants in the high-dose group, 33 (79%) of 42 participants in the low-dose group, and five (25%) of 20 participants in the placebo group. Fatigue or malaise was the most common systemic adverse event, reported in 25 (62%) participants in the high-dose group, 25 (60%) participants in the low-dose group, and five (25%) participants in the placebo group, followed by headache, reported in 23 (57%), 25 (60%), and three (15%) participants, respectively. Fever occurred 24 h after injection in 12 (30%) participants in the high-dose group and 11 (26%) participants in the low-dose group versus one (5%) participant in the placebo group. Geometric mean concentrations of IgG antibodies against Ebola glycoprotein peaked on day 28 at 51 µg/mL (95% CI 41·1-63·3) in the high-dose group, 44·9 µg/mL (25·8-56·3) in the low-dose group, and 5·2 µg/mL (3·5-7·6) in the placebo group, with respective response rates of 96% (95% CI 85·7-99·5), 96% (86·5-99·5), and 5% (0·1-24·9). Geometric mean concentrations decreased by day 180 to 25·5 µg/mL (95% CI 20·6-31·5) in the high-dose group, 22·1 µg/mL (19·3-28·6) in the low-dose group, and 3·2 µg/mL (2·4-4·9) in the placebo group. 28 (57%) participants given high-dose vaccine and 31 (61%) participants given low-dose vaccine developed glycoprotein-specific CD4 cell responses, and 33 (67%) and 35 (69%), respectively, developed CD8 responses. INTERPRETATION: ChAd3-EBO-Z was safe and well tolerated, although mild to moderate systemic adverse events were common. A single dose was immunogenic in almost all vaccine recipients. Antibody responses were still significantly present at 6 months. There was no significant difference between doses for safety and immunogenicity outcomes. This acceptable safety profile provides a reliable basis to proceed with phase 2 and phase 3 efficacy trials in Africa. FUNDING: Swiss State Secretariat for Education, Research and Innovation (SERI), through the EU Horizon 2020 Research and Innovation Programme.

Toward protein biomarkers for allergy: CD4+ T cell proteomics in allergic and nonallergic subjects sampled in and out of pollen season.

Allergy is an immunological disorder of the upper airways, lung, skin, and the gut with a growing prevalence over the last decades in Western countries. Atopy, the genetic predisposition for allergy, is strongly dependent on familial inheritance and environmental factors. These observations call for predictive markers of progression from atopy to allergy, a prerequisite to any active intervention in neonates and children (prophylactic interventions/primary prevention) or in adults (immunomodulatory interventions/secondary prevention). In an attempt to identify early biomarkers of the "atopic march" using minimally invasive sampling, CD4+ T cells from 20 adult volunteers (10 healthy and 10 with respiratory allergies) were isolated and quantitatively analyzed and their proteomes were compared in and out of pollen season (± antigen exposure). The proteome study based on high-resolution 2D gel electrophoresis revealed three candidate protein markers that distinguish the CD4+ T cell proteomes of normal from allergic individuals when sampled out of pollen season, namely Talin 1, Nipsnap homologue 3A, and Glutamate-cysteine ligase regulatory protein. Three proteins were found differentially expressed between the CD4+ T cell proteomes of normal and allergic subjects when sampled during pollen season: carbonyl reductase, glutathione S-transferase ω 1, and 2,4-dienoyl-CoA reductase. The results were partly validated by Western blotting.

A malaria vaccine that elicits in humans antibodies able to kill Plasmodium falciparum.

BACKGROUND: Plasmodium falciparum merozoite surface protein 3 is a malaria vaccine candidate that was identified, characterised, and developed based on a unique immuno-clinical approach. The vaccine construct was derived from regions fully conserved among various strains and containing B cell epitopes targeted by human antibodies (from malaria-immune adults) that are able to mediate a monocyte-dependent parasite killing effect. The corresponding long synthetic peptide was administered to 36 volunteers, with either alum or Montanide ISA720 as adjuvant. METHODS AND FINDINGS: Both formulations induced cellular and humoral immune responses. With alum, the responses lasted up to 12 mo. The vaccine-induced antibodies were predominantly of cytophilic classes, i.e., able to cooperate with effector cells. In vitro, the antibodies induced an inhibition of the P. falciparum erythrocytic growth in a monocyte-dependent manner, which was in most instances as high as or greater than that induced by natural antibodies from immune African adults. In vivo transfer of the volunteers' sera into P. falciparum-infected humanized SCID mice profoundly reduced or abrogated parasitaemia. These inhibitory effects were related to the antibody reactivity with the parasite native protein, which was seen in 60% of the volunteers, and remained in samples taken 12 mo postimmunisation. CONCLUSION: This is the first malaria vaccine clinical trial to clearly demonstrate antiparasitic activity by vaccine-induced antibodies by both in vitro and in vivo methods. The results, showing the induction of long-lasting antibodies directed to a fully conserved polypeptide, also challenge current concepts about malaria vaccines, such as unavoidable polymorphism, low antigenicity, and poor induction of immune memory.

Childhood and malaria vaccines combined in biodegradable microspheres produce immunity with synergistic interactions.

Biodegradable microspheres may represent a potential tool for the delivery of combination vaccines. We demonstrate strong immunogenicity of five co-encapsulated antigens after a single subcutaneous inoculation in guinea pigs. Tetanus- and diphtheria-specific antibodies were not significantly affected by the presence of either antigen or by the presence of pertussis or Haemophilus influenzae type b (Hib) antigens. Microsphere formulations gave better protection against diphtheria toxin than did two injections of a licensed tetravalent vaccine. Finally, a synthetic malaria peptide antigen (PfCS) also encapsulated in PLGA microspheres increased diphtheria and tetanus-specific immunity and improved protection against diphtheria. These findings demonstrate the potential of microspheres as an alternative and promising strategy for combination vaccines with a further aptitude in reducing the number of inoculations required to gain functional immunity.

OM-174, a new adjuvant with a potential for human use, induces a protective response when administered with the synthetic C-terminal fragment 242-310 from the circumsporozoite protein of Plasmodium berghei.

The goal of this project was the evaluation of a novel immunomodulatory adjuvant for human use, OM-174, which is a soluble adjuvant derived from Escherichia coli lipid A. For this study, we used a synthetic peptide, known for its safety and reproducibility and the murine model of BALB/c mice. The long peptide (PbCS 242-310) used corresponds to the C-terminal region of the circumsporozoite protein (CSP) that is the major protein on the surface of Plasmodium sporozoites. Subcutaneous injections of PbCS 242-310 in combination with soluble adjuvant OM-174 induced long lasting peptide-specific antibody titres comparable to those obtained by immunization with incomplete Freund's adjuvant (IFA). The ex vivo evaluation of the CD8(+) T cell response by IFN-gamma ELISPOT assay revealed that the injection of polypeptide with OM-174 adjuvant induced, compared to IFA, a similar and an eight-fold increased frequency of peptide-specific lymphocytes in the draining lymph-nodes and in the spleen, respectively. The CD8(+) T-cells are specific for the sequence PbCS 245-253, a well-known H-2K(d)-restricted CTL epitope, and are cytotoxic as shown in a chromium release assay. Immunization of BALB/c mice with this polypeptide in combination with adjuvant OM-174 conferred a protection after challenge with live Plasmodium berghei sporozoites.The strong antibody and CTL responses observed to a synthetic peptide in mice, the safety profile of the adjuvant and its extensive physico-chemical characterization suggest that OM-174 has a potential use in vaccine formulations for humans.

Encapsulation of peptides in biodegradable microspheres prolongs their MHC class-I presentation by dendritic cells and macrophages in vitro.

Biodegradable microspheres (MS) consisting of poly(D,L-lactide-co-glycolide) (PLGA) represent a promising alternative to conventional adjuvants. The adjustable pulsatile release of encapsulated material from such MS offers the potential to mimic the priming and boosting injections of conventional immunization regimens. In this paper, we demonstrate that MS can serve as antigen reservoirs in antigen presenting cells (APC), so that antigen is presented for extended periods of time (up to 9 days). In particular, we could show by measurement of IFN-gamma production that encapsulated peptides were presented to cytotoxic T lymphocytes (CTL) by mouse and human macrophages as well as by human dendritic cells in vitro for a longer time period as compared to soluble peptides. The extended antigen presentation may thus improve the CTL response in vivo. These results may be of paramount importance in cancer vaccination therapy since MS may serve as antigen reservoirs to extend the presentation time by APC used to boost the patient's immune response to tumor antigens.