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Contains fulltext : 291067.pdf (Publisher’s version ) (Open Access) BACKGROUND: Capsid virus-like particles (cVLP) have proven safe and immunogenic and can be a versatile platform to counter pandemics. We aimed to clinically test a modular cVLP COVID-19 vaccine in individuals who were naive to SARS-CoV-2. METHODS: In this phase 1, single-centre, dose-escalation, adjuvant-selection, open-label clinical trial, we recruited participants at the Radboud University Medical Center in Nijmegen, Netherlands, and sequentially assigned them to seven groups. Eligible participants were healthy, aged 18-55 years, and tested negative for SARS-CoV-2 and anti-SARS-CoV-2 antibodies. Participants were vaccinated intramuscularly on days 0 and 28 with 6 μg, 12 μg, 25 μg, 50 μg, or 70 μg of the cVLP-based COVID-19 vaccine (ABNCoV2). A subgroup received MF59-adjuvanted ABNCoV2. Follow-up was for 24 weeks after second vaccination. The primary objectives were to assess the safety and tolerability of ABNCoV2 and to identify a dose that optimises the tolerability-immunogenicity ratio 14 days after the first vaccination. The primary safety endpoint was the number of related grade 3 adverse events and serious adverse events in the intention-to-treat population. The primary immunogenicity endpoint was the concentration of ABNCoV2-specific antibodies. The trial is registered with ClinicalTrials.gov, NCT04839146. FINDINGS: 45 participants (six to nine per group) were enrolled between March 15 and July 15, 2021. Participants had a total of 249 at least possibly related solicited adverse events (185 grade 1, 63 grade 2, and one grade 3) within a week after vaccination. Two serious adverse events occurred; one was classified as a possible adverse reaction. Antibody titres were dose-dependent with levels plateauing at a vaccination dose of 25-70 μg ABNCoV2. After second vaccination, live virus neutralisation activity against major SARS-CoV-2 variants was high but was lower with an omicron (BA.1) variant. Vaccine-specific IFNγ(+) CD4(+) T cells were induced. INTERPRETATION: Immunisation with ABNCoV2 was well tolerated, safe, and resulted in a functional immune response. The data support the need for additional clinical development of ABNCoV2 as a second-generation SARS-CoV-2 vaccine. The modular cVLP platform will accelerate vaccine development, beyond SARS-CoV-2. FUNDING: EU, Carlsberg Foundation, and the Novo Nordisk Foundation.

ES2B-C001 is a virus-like particle (VLP) vaccine against human HER-2, developed for the therapy of breast cancer. We show here that ES2B-C001 effectively inhibits mammary carcinoma growth and metastasis in a transgenic mouse model expressing activated human HER-2. ES2B-C001 vaccine is a tag/catcher conjugation system: Acinectobacter phage 205 (AP205) capsid VLP, each with 180 tag peptides, are conjugated with catcher-HER-2 extracellular domain. The vaccine was administered alone, thanks to the intrinsic adjuvanticity of the VLP, or with Montanide ISA 51. QD is a HER-2-positive cell line established from a mammary carcinoma of a Delta16 (FVB background) transgenic mouse, bearing the human HER-2 splice variant Delta16. FVB female mice were challenged in the mammary fat pad with 1 million QD cells; vaccinations started 2 weeks after cell challenge and were repeated every 2 weeks. Untreated mice developed progressive tumors within one month, whereas 70% of mice vaccinated without adjuvant and all mice vaccinated with adjuvant were still tumor-free one year after cell challenge. Mice challenged intravenously (i.v.) developed more than 300 lung metastases, whereas all vaccinated mice remained metastasis-free. Delta16 transgenic mice are immunologically tolerant to human HER-2 and develop aggressive mammary carcinomas with a median latency of 5 months. Vaccination of young, tumor-free Delta16 mice completely prevented tumor onset for more than one year. Delta16 mice challenged i.v. with QD cells mice developed a mean of 68 lung nodules, whereas 73% of mice therapeutically vaccinated without adjuvant, and all mice vaccinated with E2SB-C001+ISA 51, were free from metastases. ES2B-C001 induced copious anti-HER-2 antibodies of all IgG subclasses, ranging 1-10 mg/mL in FVB mice and 0.1-1 mg/mL in Delta16 mice; antibody titers remained very high for 6-10 months after the last vaccination. Antibodies inhibited the 3D growth of human HER-2+++ and HER-2++ breast cancer cells, of trastuzumab resistant cells and of gastric carcinoma cells. Vaccination increased interferon-gamma secreting cells in the spleen, as evaluated by ELISPot (21±3 spots/2x105 cells). The results warrant further development of ES2B-C001 for the therapy of HER-2 positive human breast cancer and of other tumors expressing HER-2. Citation Format: Francesca Ruzzi, Arianna Palladini, Stine Clemmensen, Annette Strobaek, Nicolaas Buijs, Tanja Domeyer, Jerzy Dorosz, Vladislav Soroka, Dagmara Grzadziela, Christina Jo Rasmussen, Ida Busch Nielsen, Max Soegaard, Maria Sofia Semprini, Laura Scalambra, Stefania Angelicola, Lorena Landuzzi, Pier-Luigi Lollini, Mette Thorn. Preclinical activity of ES2B-C001, a human candidate HER-2 virus-like particle (VLP) vaccine, against mammary carcinoma onset and metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 687.

Background Malaria in pregnancy has major impacts on mother and child health. To complement existing interventions, such as intermittent preventive treatment and use of impregnated bed nets, we developed a malaria vaccine candidate with the aim of reducing sequestration of asexual “blood-stage” parasites in the placenta, the major virulence mechanism. Methods The vaccine candidate PAMVAC is based on a recombinant fragment of VAR2CSA, the Plasmodium falciparum protein responsible for binding to the placenta via chondroitin sulfate A (CSA). Healthy, adult malaria-naive volunteers were immunized with 3 intramuscular injections of 20 μg (n = 9) or 50 μg (n = 27) PAMVAC, adjuvanted with Alhydrogel or glucopyranosyl lipid adjuvant in stable emulsion (GLA-SE) or in a liposomal formulation with QS21 (GLA-LSQ). Allocation was random and double blind. The vaccine was given every 4 weeks. Volunteers were observed for 6 months following last immunization. Results All PAMVAC formulations were safe and well tolerated. A total of 262 adverse events (AEs) occurred, 94 (10 grade 2 and 2 grade 3) at least possibly related to the vaccine. No serious AEs occurred. Distribution and severity of AEs were similar in all arms. PAMVAC was immunogenic in all participants. PAMVAC-specific antibody levels were highest with PAMVAC-GLA-SE. The antibodies inhibited binding of VAR2CSA expressing P. falciparum-infected erythrocytes to CSA in a standardized functional assay. Conclusions PAMVAC formulated with Alhydrogel or GLA-based adjuvants was safe, well tolerated, and induced functionally active antibodies. Next, PAMVAC will be assessed in women before first pregnancies in an endemic area. Clinical Trials Registration EudraCT 2015-001827-21; ClinicalTrials.gov NCT02647489., The pregnancy-associated malaria-vaccine candidate PAMVAC is safe and well tolerated with all three tested formulations and induces functional binding-inhibitory antibodies. The vaccine with glucopyranosyl lipid adjuvant (GLA) in stable emulsion is superior to Alhydrogel and a GLA/QS21 liposomal formulation.

Background Malaria in pregnancy is associated with significant morbidity in pregnant women and their offspring. Plasmodium falciparum infected erythrocytes (IE) express VAR2CSA that mediates binding to chondroitin sulphate A (CSA) in the placenta. Two VAR2CSA-based vaccines for placental malaria are in clinical development. The purpose of this study was to evaluate the robustness and comparability of binding inhibition assays used in the clinical development of placental malaria vaccines. Methods The ability of sera from animals immunised with different VAR2CSA constructs to inhibit IE binding to CSA was investigated in three in vitro assays using 96-well plates, petri dishes, capillary flow and an ex vivo placental perfusion assay. Results The inter-assay variation was not uniform between assays and ranged from above ten-fold in the flow assay to two-fold in the perfusion assay. The intra-assay variation was highest in the petri dish assay. A positive correlation between IE binding avidity and the level of binding after antibody inhibition in the petri dish assay indicate that high avidity IE binding is more difficult to inhibit. The highest binding inhibition sensitivity was found in the 96-well and petri dish assays compared to the flow and perfusion assays where binding inhibition required higher antibody titers. Conclusions The inhibitory capacity of antibodies is not easily translated between assays and the high sensitivity of the 96-well and petri dish assays stresses the need for comparing serial dilutions of serum. Furthermore, IE binding avidity must be in the same range when comparing data from different days. There was an overall concordance in the capacity of antibody-mediated inhibition, when comparing the in vitro assays with the perfusion assay, which more closely represents in vivo conditions. Importantly the ID1-ID2a protein in a liposomal formulation, currently in a phase I trial, effectively induced antibodies that inhibited IE adhesion in placental tissue.

Plasmodium falciparum reticulocyte-binding protein homolog 5 (PfRH5) is a leading asexual blood-stage vaccine candidate for malaria. In preparation for clinical trials, a full-length PfRH5 protein vaccine called “RH5.1” was produced as a soluble product under cGMP using the ExpreS2 platform (based on a Drosophila melanogaster S2 stable cell line system). Following development of a high-producing monoclonal S2 cell line, a master cell bank was produced prior to the cGMP campaign. Culture supernatants were processed using C-tag affinity chromatography followed by size exclusion chromatography and virus-reduction filtration. The overall process yielded >400 mg highly pure RH5.1 protein. QC testing showed the MCB and the RH5.1 product met all specified acceptance criteria including those for sterility, purity, and identity. The RH5.1 vaccine product was stored at −80 °C and is stable for over 18 months. Characterization of the protein following formulation in the adjuvant system AS01B showed that RH5.1 is stable in the timeframe needed for clinical vaccine administration, and that there was no discernible impact on the liposomal formulation of AS01B following addition of RH5.1. Subsequent immunization of mice confirmed the RH5.1/AS01B vaccine was immunogenic and could induce functional growth inhibitory antibodies against blood-stage P. falciparum in vitro. The RH5.1/AS01B was judged suitable for use in humans and has since progressed to phase I/IIa clinical trial. Our data support the future use of the Drosophila S2 cell and C-tag platform technologies to enable cGMP-compliant biomanufacture of other novel and “difficult-to-express” recombinant protein-based vaccines., Malaria: Successful clinical trial preparation for blood-stage vaccine A vaccine candidate for blood-stage malaria has overcome previous hurdles to enter clinical trials. The protein PfRH5 is an essential blood-stage infection facilitator of malarial parasite Plasmodium falciparum, and a promising target for vaccine strategies. Unfortunately, efforts to produce the protein in an immunogenic, clinically-viable way have been met with difficulty. Here, researchers led by Simon Draper, from the UK’s Jenner Institute, used a fruit fly expression system to produce over 400 mg of high-purity protein. Formulated with an immunity-boosting adjuvant, the vaccine elicited antibodies in mice that proved inhibitory to blood-stage P. falciparum during in vitro assays. The PfRH5 vaccine candidate and its adjuvant have been approved for a clinical trial in the UK, and the authors hope that the expression system used may be beneficial in the expression of other ‘difficult’ proteins.