Modelling the Interaction Between Rationally-designed Synthetic Model Viral Protein Immunogens

Study Overview
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Brief Summary
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EVAI2020_01 is a single blinded two part experimental medicine study to determine the extent to which different prime-boost combinations of model immunogens based on HIV-1 envelope proteins (ConM and ConS), influence the breadth of viruses neutralised by induced antibodies and the associated diversity of B and T cell responses. Our research will investigate the effect of a second immunisation challenge with a combination of three model mosaic envelope proteins designed to increase the breadth of induced antibody neutralisation. The primary outcome will be measurement of specific viral neutralisation activity of serum antibodies. Exploratory outcomes will include characterisation of blood B and T cell responses to these model immunogens.

Detailed Description
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One of the most effective arms of the human immune system is the ability of very low concentrations of antibody proteins to bind to viruses, bacteria and toxins and neutralise their activity or ability to infect. In contrast to cellular immunity, which may cause tissue destruction and pathology, antibody-mediated immunity can be very passive, while completely preventing infection. How antibodies bind their targets varies enormously, ranging from unhelpful blocking antibodies or narrowly focussed neutralising antibodies, to highly protective broadly neutralising antibodies (bNAbs) that can neutralise a wide range of strains of the same pathogen. Such bNAbs are especially sought after in virus infections such as HIV, influenza and others where the virus mutates to evade immune responses that are too narrow or focussed. Antibodies arise when an immunogen (an immunogen is anything that induces an immune response, typically a foreign protein) is taken up by the immune system and shown to white blood cells - T and B cells - by specialised immune cells. In some cases the T and B cells bind the immunogens to receptors on their surface, triggering an immune response in which T cells help B cells to manufacture specific antibodies. The events around how the protein is processed into manageable pieces, shown to the T and B cells, and the pattern of chemical signals produced by the immune cells is highly complex, but eventually determines how broad the antibody response will be (its breadth). For infections like HIV and influenza, decades of research and clinical vaccine trials have had limited or no success. To take HIV as an example, investigators have an almost complete lack of understanding of how immunogens interact with the naive human B cell receptor (BCR) repertoire and the pathways required to induce bNAbs during an infection or after an immunisation. Animal models have failed as the naïve, germline encoded, B cell antibody receptor repertoires of non-human species are sufficiently different from those of humans to render design and selection of vaccine based on non-human species problematic. Additionally, bNAbs isolated from HIV-1-infected individuals have structural features that occur rarely or not at all in other mammals, such as unusually long loop-binding regions (CDRH3 loops) required to penetrate past glycans on the surface of the envelope spike that shield key neutralising epitopes (Mascola JR 2013). There is therefore a critical need to better understand, in human experimental medicine models of immune challenge, how immunogens and B/T cells interact in the development of protective bNAb anti-viral responses. Our approach to resolving this impasse is to challenge the human immune system with rationally-designed model immunogens to determine the structural and other characteristics required to drive human B cell antibody responses towards neutralisation breadth. Investigators have selected HIV as an experimental model as there is a reasonable understanding about the specificity and function of anti-HIV bNAbs, as well as an urgent need to identify novel immunisation approaches following decades of failed or poorly successful trials. There is also a huge database of safety using HIV proteins as immunogens, and the technological expertise to design and manufacture HIV viral proteins. Assays for HIV neutralising activity are also well established in our laboratories. Although focussed on HIV, our findings will be applicable to other viral infections. The model immunogens proposed in the experimental medicine studies are unlikely to be suitable as vaccines, and any clinical development would require iterative cycles of design refinement and development based on immunological insights gleaned from these experimental investigations. Therefore, the focus is on in-depth characterisation of the elicited immune response to rationally-designed model immunogens that may inform the design process of actual vaccines. This experimental medicine approach is only now possible due to unprecedented progress in our abilities to study the human immune system and to obtain complete information on immune responses to vaccination, since performing research on the human immune system is now almost as easy as it has been in mice. The main focus of this study will be to determine which of the design strategies is able to prime human germline (naive) B cells and drive antibody responses towards induction of neutralising antibody breadth. Our range of model immunogens will be based on the envelope (Env) glycoprotein of HIV-1, which is the only target of neutralising antibodies, and therefore the only virally-encoded immunogen relevant for induction of such antibodies by immunisation. To ensure reproducibility of results and the highest level of volunteer safety, all immunogens will be manufactured under cGMP, using techniques applied to vaccine immunogens. Env has extensive amino acid variation, structural and conformational instability, and immunodominance of hypervariable regions (Kwong PD, 2011; Sattentau QJ, 2013). Our team designed soluble immunogens that closely mimic the native viral trimer in situ, but that incorporate design strategies that may alter the intrinsic viral immune evasion mechanisms (Sanders RW, 2013). Env is made up of three identical complexes (trimers) each of which contains two molecules, gp120 and gp41 that can be modified to make a soluble molecule called gp140, upon which our immunogens are based. Investigators have developed model consensus gp140 Env trimers (consensus of all global strains) designed to prime B cell responses to common epitopes represented in all HIV-1 subtypes. Investigators have utilised two design strategies to stabilise these in a native-like conformation: ConM SOSIP and ConS UFO. The ConM SOSIP trimer includes novel mutations that include the incorporation of a disulphide linkage between the gp120 and gp41 ectodomain (making up gp140) which prevents their disassociation into monomer subunits. The ConS UFO includes a short flexible amino-acid linker to tether the gp120 and gp41 subunits together as an alternative strategy to prevent dissociation of the Env trimer. Investigators wish to test both designs to determine the effect on B cell repertoire. To further stabilize global architecture, investigators employed an EDC crosslinking approach that has been shown to conserve bNAb epitopes, reduce non-antiviral antibody responses, and enhance overall immunogen stability (Schiffner et al., 2015). Thus, in Part 1 of this study investigators will test EDC ConM SOSIP and EDC ConS UFO versions in parallel. A critical adjunct to our consensus-based model design is to use a cocktail of three mosaic gp140 Env trimers as a boost (Part 2) to overcome the immunodominance of hypervariable regions of Env and to determine whether this will focus antibody responses towards conserved neutralisation epitopes. While designed using computer algorithms, these mosaics represent authentic Env structures that are fully functional and native in their conformation. Our novel designs aim to eliminate unwanted immunodominant antibody responses and focus B cells towards highly conserved supersites of vulnerability on Env, with particular emphasis on quaternary bNAb epitopes (Julien, JP, 2013; Kong L, 2013; Lyumkis D, 2013). The extent to which these different strategies may induce neutralising breadth, and the identification of the mechanisms and drivers involved, can only be determined empirically through human immunogen challenge studies.

Official Title
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An Experimental Medicine Study Modelling the Interaction Between Rationally-designed Synthetic Model Viral Protein Immunogens and the Breadth of the Induced B and T Cell Repertoires.

Conditions
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HIV-1-infection

Intervention / Treatment
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* Biological: ConM SOSIP
* Biological: EDC ConM SOSIP
* Biological: ConS UFO
* Biological: EDC ConS UFO
* Biological: Mosaic SOSIPs


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 1. Healthy male and female volunteers aged between 18 and 55 years. 2. Available for ALL follow-up visits for the duration of the study. 3. Entered and clearance obtained from The Over volunteering Prevention System (TOPS) database (to avoid impact of any co-administered investigational products or treatments on our outcomes). 4. Women capable of becoming pregnant willing to take hormonal contraception for the duration of the study. 5. Willing and able to give written informed consent. Exclusion Criteria: 1. History of any medical, psychological or other condition, clinically significant laboratory result at screening, or use of any medications which, in the opinion of the investigators, would interfere with the study objectives or volunteers safety. 2. HIV-1 or HIV-2 antibody positive or indeterminate upon screening, or history of receipt of Env-based HIV immunogens (which would render the volunteers non-naive to the model immunogens). 3. Unable to read and/or speak English to a fluency level adequate for the full comprehension of study procedures and consent.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 55 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Sequential Assignment
Interventional Model Description: This is a single-blind study with volunteers being randomised into five groups of n=10 (Groups A-E) stratified by gender
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: ConM SOSIP and Mosaic SOSIPs<br>ConM SOSIP 100g Intramuscular injections into the left or right arm Administered at 0, 3 and 6 months Mosaic SOSIPs 100ug (3x33ug) Intramuscular injections into the left or right arm Administered at 12 months only | Biological: ConM SOSIP<br>* Recombinant HIV-1 trimeric gp140 Env protein: ConM SOSIP gp140. Model immunogens will be used at the dosage of 100 ug and will be admixed with 500 ug MPLA formulated in liposomes and administered by intramuscular injection into the left or right deltoid muscle.<br>Biological: Mosaic SOSIPs<br>* Mosaic gp140 Env trimers designed to overcome the immunodominance of hypervariable regions of Env The immunogen will be used at the dosage of 100 ug (3x33ug) and will be admixed with 500 ug MPLA formulated in liposomes and administered by intramuscular injection into the left or right deltoid muscle.<br>|
| Active Comparator: EDC ConM SOSIP and Mosaic SOSIPs<br>EDC ConM SOSIP 100G Intramuscular injections into the left or right arm Administered at 0, 3 and 6 months Mosaic SOSIPs 100ug (3x33ug) Intramuscular injections into the left or right arm Administered at 12 months only | Biological: EDC ConM SOSIP<br>* Chemically fixed version of recombinant HIV-1 trimeric gp140 Env: EDC-ConM SOSIP. Model immunogens will be used at the dosage of 100 ug and will be admixed with 500 ug MPLA formulated in liposomes and administered by intramuscular injection into the left or right deltoid muscle.<br>Biological: Mosaic SOSIPs<br>* Mosaic gp140 Env trimers designed to overcome the immunodominance of hypervariable regions of Env The immunogen will be used at the dosage of 100 ug (3x33ug) and will be admixed with 500 ug MPLA formulated in liposomes and administered by intramuscular injection into the left or right deltoid muscle.<br>|
| Active Comparator: ConS UFO and Mosaic SOSIPs<br>ConS UFO 100g Intramuscular injections into the left or right arm Administered at 0, 3 and 6 months Mosaic SOSIPs 100ug (3x33ug) Intramuscular injections into the left or right arm Administered at 12 months only | Biological: ConS UFO<br>* Recombinant HIV-1 trimeric gp140 Env protein: ConS UFO gp140. Model immunogens will be used at the dosage of 100 ug and will be admixed with 500 ug MPLA formulated in liposomes and administered by intramuscular injection into the left or right deltoid muscle<br>Biological: Mosaic SOSIPs<br>* Mosaic gp140 Env trimers designed to overcome the immunodominance of hypervariable regions of Env The immunogen will be used at the dosage of 100 ug (3x33ug) and will be admixed with 500 ug MPLA formulated in liposomes and administered by intramuscular injection into the left or right deltoid muscle.<br>|
| Active Comparator: EDC ConS UFO and Mosaic SOSIPs<br>EDC ConS UFO 100g Intramuscular injections into the left or right arm Administered at 0, 3 and 6 months Mosaic SOSIPs 100ug (3x33ug) Intramuscular injections into the left or right arm Administered at 12 months only | Biological: EDC ConS UFO<br>* Chemically fixed version of recombinant HIV-1 trimeric gp140 Env : EDC-ConS UFO. Model immunogens will be used at the dosage of 100 ug and will be admixed with 500 ug MPLA formulated in liposomes and administered by intramuscular injection into the left or right deltoid muscle.<br>Biological: Mosaic SOSIPs<br>* Mosaic gp140 Env trimers designed to overcome the immunodominance of hypervariable regions of Env The immunogen will be used at the dosage of 100 ug (3x33ug) and will be admixed with 500 ug MPLA formulated in liposomes and administered by intramuscular injection into the left or right deltoid muscle.<br>|
| Active Comparator: ConS UFO and ConM SOSIPs and Mosaic SOSIPs<br>ConS UFO 100g Intramuscular injections into the left or right arm Administered at 0 and 3 months ConM SOSIP Administered at 12 months Mosaic SOSIPs 100ug (3x33ug) Intramuscular injections into the left or right arm Administered at 12 months only | Biological: EDC ConM SOSIP<br>* Chemically fixed version of recombinant HIV-1 trimeric gp140 Env: EDC-ConM SOSIP. Model immunogens will be used at the dosage of 100 ug and will be admixed with 500 ug MPLA formulated in liposomes and administered by intramuscular injection into the left or right deltoid muscle.<br>Biological: ConS UFO<br>* Recombinant HIV-1 trimeric gp140 Env protein: ConS UFO gp140. Model immunogens will be used at the dosage of 100 ug and will be admixed with 500 ug MPLA formulated in liposomes and administered by intramuscular injection into the left or right deltoid muscle<br>Biological: Mosaic SOSIPs<br>* Mosaic gp140 Env trimers designed to overcome the immunodominance of hypervariable regions of Env The immunogen will be used at the dosage of 100 ug (3x33ug) and will be admixed with 500 ug MPLA formulated in liposomes and administered by intramuscular injection into the left or right deltoid muscle.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Neutralising antibodies | Serum titres of neutralising antibodies to virus expressing ConM and ConS envelopes | 6 Months | 
| Viral expression of Mosaic envelopes (1-3) | Serum titres of neutralising antibodies to virus expressing Mosaic envelopes (1-3) | 12 Months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Binding antibodies in serum | Measurement of the magnitude and phenotype of B cell (plasmablast and memory B cells) and T cell responses (CD4 and CD8) in peripheral blood mononuclear cells (PBMC) | 18 Months | 
| Paxgene blood transcriptomics | Paxgene tubes for blood transcriptomics will be collected only from group A | 18 Months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Antibody, Antibody-dependent cell-mediated cytotoxicity, Neuralizing antibody responses