A Phase 1, Randomised, Double-Blind, Placebo-Controlled, Dosage-Escalation, Single Centre Study to Evaluate the Safety and Immunogenicity of an Adjuvanted SARS-CoV-2 Sclamp Protein Subunit Vaccine in Healthy Adults Aged 18 to 55 Years Old and Healthy Older Adults, Aged 56 Years and Over
This study is being conducted to look at the safety and immune response (how the immune system of the human body reacts) to a vaccine for SARS-CoV-2 (the virus responsible for COVID-19 infection) when administered as an intramuscular injection (an injection directly into the muscle) to the upper arm of healthy participants, on two occasions at least 28 days apart.
Safety and immunogenicity of an MF59-adjuvanted spike glycoprotein-clamp vaccine for SARS-CoV-2: a randomised, double-blind, placebo-controlled, phase 1 trial.
1区 · 医学
作者: Keith J Chappell ; Francesca L Mordant ; Zheyi Li ; Danushka K Wijesundara ; Paula Ellenberg ; Julia A Lackenby ; Stacey T M Cheung ; Naphak Modhiran ; Michael S Avumegah ; Christina L Henderson ; Kym Hoger ; Paul Griffin ; Jillian Bennet ; Luca Hensen ; Wuji Zhang ; Thi H O Nguyen ; Sara Marrero-Hernandez ; Kevin J Selva ; Amy W Chung ; Mai H Tran ; Peter Tapley ; James Barnes ; Patrick C Reading ; Suellen Nicholson ; Stavroula Corby ; Thomas Holgate ; Bruce D Wines ; P Mark Hogarth ; Katherine Kedzierska ; Damian F J Purcell ; Charani Ranasinghe ; Kanta Subbarao ; Daniel Watterson ; Paul R Young ; Trent P Munro
Given the scale of the ongoing COVID-19 pandemic, the development of vaccines based on different platforms is essential, particularly in light of emerging viral variants, the absence of information on vaccine-induced immune durability, and potential paediatric use. We aimed to assess the safety and immunogenicity of an MF59-adjuvanted subunit vaccine for COVID-19 based on recombinant SARS-CoV-2 spike glycoprotein stabilised in a pre-fusion conformation by a novel molecular clamp (spike glycoprotein-clamp [sclamp]).
We did a phase 1, double-blind, placebo-controlled, block-randomised trial of the sclamp subunit vaccine in a single clinical trial site in Brisbane, QLD, Australia. Healthy adults (aged ≥18 to ≤55 years) who had tested negative for SARS-CoV-2, reported no close contact with anyone with active or previous SARS-CoV-2 infection, and tested negative for pre-existing SARS-CoV-2 immunity were included. Participants were randomly assigned to one of five treatment groups and received two doses via intramuscular injection 28 days apart of either placebo, sclamp vaccine at 5 μg, 15 μg, or 45 μg, or one dose of sclamp vaccine at 45 μg followed by placebo. Participants and study personnel, except the dose administration personnel, were masked to treatment. The primary safety endpoints included solicited local and systemic adverse events in the 7 days after each dose and unsolicited adverse events up to 12 months after dosing. Here, data are reported up until day 57. Primary immunogenicity endpoints were antigen-specific IgG ELISA and SARS-CoV-2 microneutralisation assays assessed at 28 days after each dose. The study is ongoing and registered with ClinicalTrials.gov, NCT04495933.
Between June 23, 2020, and Aug 17, 2020, of 314 healthy volunteers screened, 120 were randomly assigned (n=24 per group), and 114 (95%) completed the study up to day 57 (mean age 32·5 years [SD 10·4], 65 [54%] male, 55 [46%] female). Severe solicited reactions were infrequent and occurred at similar rates in participants receiving placebo (two [8%] of 24) and the SARS-CoV-2 sclamp vaccine at any dose (three [3%] of 96). Both solicited reactions and unsolicited adverse events occurred at a similar frequency in participants receiving placebo and the SARS-CoV-2 sclamp vaccine. Solicited reactions occurred in 19 (79%) of 24 participants receiving placebo and 86 (90%) of 96 receiving the SARS-CoV-2 sclamp vaccine at any dose. Unsolicited adverse events occurred in seven (29%) of 24 participants receiving placebo and 35 (36%) of 96 participants receiving the SARS-CoV-2 sclamp vaccine at any dose. Vaccination with SARS-CoV-2 sclamp elicited a similar antigen-specific response irrespective of dose: 4 weeks after the initial dose (day 29) with 5 μg dose (geometric mean titre [GMT] 6400, 95% CI 3683-11 122), with 15 μg dose (7492, 4959-11 319), and the two 45 μg dose cohorts (8770, 5526-13 920 in the two-dose 45 μg cohort; 8793, 5570-13 881 in the single-dose 45 μg cohort); 4 weeks after the second dose (day 57) with two 5 μg doses (102 400, 64 857-161 676), with two 15 μg doses (74 725, 51 300-108 847), with two 45 μg doses (79 586, 55 430-114 268), only a single 45 μg dose (4795, 2858-8043). At day 57, 67 (99%) of 68 participants who received two doses of sclamp vaccine at any concentration produced a neutralising immune response, compared with six (25%) of 24 who received a single 45 μg dose and none of 22 who received placebo. Participants receiving two doses of sclamp vaccine elicited similar neutralisation titres, irrespective of dose: two 5 μg doses (GMT 228, 95% CI 146-356), two 15 μg doses (230, 170-312), and two 45 μg doses (239, 187-307).
This first-in-human trial shows that a subunit vaccine comprising mammalian cell culture-derived, MF59-adjuvanted, molecular clamp-stabilised recombinant spike protein elicits strong immune responses with a promising safety profile. However, the glycoprotein 41 peptide present in the clamp created HIV diagnostic assay interference, a possible barrier to widespread use highlighting the criticality of potential non-spike directed immunogenicity during vaccine development. Studies are ongoing with alternative molecular clamp trimerisation domains to ameliorate this response.
Coalition for Epidemic Preparedness Innovations, National Health and Medical Research Council, Queensland Government, and further philanthropic sources listed in the acknowledgments.
Preclinical development of a molecular clamp-stabilised subunit vaccine for severe acute respiratory syndrome coronavirus 2.
3区 · 医学
作者: Daniel Watterson ; Danushka K Wijesundara ; Naphak Modhiran ; Francesca L Mordant ; Zheyi Li ; Michael S Avumegah ; Christopher Ld McMillan ; Julia Lackenby ; Kate Guilfoyle ; Geert van Amerongen ; Koert Stittelaar ; Stacey Tm Cheung ; Summa Bibby ; Mallory Daleris ; Kym Hoger ; Marianne Gillard ; Eve Radunz ; Martina L Jones ; Karen Hughes ; Ben Hughes ; Justin Goh ; David Edwards ; Judith Scoble ; Lesley Pearce ; Lukasz Kowalczyk ; Tram Phan ; Mylinh La ; Louis Lu ; Tam Pham ; Qi Zhou ; David A Brockman ; Sherry J Morgan ; Cora Lau ; Mai H Tran ; Peter Tapley ; Fernando Villalón-Letelier ; James Barnes ; Andrew Young ; Noushin Jaberolansar ; Connor Ap Scott ; Ariel Isaacs ; Alberto A Amarilla ; Alexander A Khromykh ; Judith Ma van den Brand ; Patrick C Reading ; Charani Ranasinghe ; Kanta Subbarao ; Trent P Munro ; Paul R Young ; Keith J Chappell
Efforts to develop and deploy effective vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continue at pace. Here, we describe rational antigen design through to manufacturability and vaccine efficacy of a prefusion-stabilised spike (S) protein, Sclamp, in combination with the licensed adjuvant MF59 'MF59C.1' (Seqirus, Parkville, Australia).
A panel recombinant Sclamp proteins were produced in Chinese hamster ovary and screened in vitro to select a lead vaccine candidate. The structure of this antigen was determined by cryo-electron microscopy and assessed in mouse immunogenicity studies, hamster challenge studies and safety and toxicology studies in rat.
In mice, the Sclamp vaccine elicits high levels of neutralising antibodies, as well as broadly reactive and polyfunctional S-specific CD4+ and cytotoxic CD8+ T cells in vivo. In the Syrian hamster challenge model (n = 70), vaccination results in reduced viral load within the lung, protection from pulmonary disease and decreased viral shedding in daily throat swabs which correlated strongly with the neutralising antibody level.
The SARS-CoV-2 Sclamp vaccine candidate is compatible with large-scale commercial manufacture, stable at 2-8°C. When formulated with MF59 adjuvant, it elicits neutralising antibodies and T-cell responses and provides protection in animal challenge models.