COVID-19 Vaccine: New Generation NovaVax’s NVX-CoV2373 Recombinant Particle Vaccine Shows Encouraging Results In Phase I Trial
Source: COVID-19 Vaccine Aug 10, 2020 4 years, 3 months, 4 days, 3 hours, 36 minutes ago
COVID-19 Vaccine: Results of the phase one trial of NovaVAx’s NVX-CoV2373 recombinant nanoparticle vaccine that is manufactured at Emergent Biosolutions, was found to be well tolerated and immunogenic including inducing T-cell response and neutralization antibodies four-fold higher than the mean observed in hospitalized COVID-19 patients.
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Though several promising candidates are already on the horizon, this new vaccine generation based on nanoparticles has excellent potential in avoiding the limitations of conventional or subunit vaccines.
Importantly, the latest advances in bioengineering allow the design of nanoparticles by precisely controlling shape, size, functionality, and surface traits leading in turn to improved antigen presentation and robust immunogenicity.
The clinical trial findings of the phase one trial were published on a preprint server.
https://www.medrxiv.org/content/10.1101/2020.08.05.20168435v1
Recent studies appraising a recombinant seasonal influenza hemagglutinin nanoparticle vaccine, adjuvanted with Matrix-M1, suggested that the combination of this adjuvant with nanoparticle vaccine is not only safe but could also induce robust functional antibody and T-cell responses in elderly individuals with or without comorbidities.
Hence a similar approach was quickly pursued against SARS-CoV-2 as well. The first-in-human, phase 1 clinical trial, led by Dr. Cheryl Keech from Novavax Inc. in Gaithersburg-America, evaluated both the safety and immunogenicity of NVX-CoV2373 vaccine candidate (with or without Matrix-M1 adjuvant) at two phase 1 clinical units in Australia.
The NVX-CoV2373 candidate is a recombinant nanoparticle vaccine manufactured from the full-length, wild-type SARS-CoV-2 spike glycoprotein. It is coupled with a saponin-based Matrix-M adjuvant in order to enhance the immune response and produce high levels of neutralizing antibodies, which are pivotal in halting the infection.
In summary, this was a randomized, placebo-controlled, observer-blinded, phase 1 clinical trial in 131 healthy adults aged 18 to 59. Trial vaccination consisted of two intramuscular injections, which were administered 21 days apart.
The main primary outcomes were reactogenicity, safety profile, and IgG anti-spike protein response. Secondary outcomes included adverse events appraisal, wild-type virus-neutralizing antibody production, as well as T- cell response.
As this was a phase 1 clinical trial, unsolicited adverse events were assessed diligently for causality (not related and related) and clinical severity (mild, moderate, and severe). Assessments also included adverse events of special interest (AESI) relevant to COVID-19 and possible immune-mediated medical conditions.
From the primary immunogenicity and safety analyses, it was found that in healthy adult participants, the two-dose regimens of 5 and 25 micrograms of NVX-CoV2373/Matrix-M1 were not only well-tolerated but also induced the most robust immune responses. The latter consisted of high levels of neutralizing antibodies in close correlation with anti-spike IgG.
Dr Gregory M. Glenn, one of the key researchers from NovaVax told Thailand Medical News, "Furthermore, neutralizing antibody resp
onses following second vaccination was of the magnitude seen in convalescent serum from hospitalized COVID-19 patients and exceeded overall convalescent sera GMT by four-fold.”
The benefits of the Matrix-M1 adjuvant was clear considering the induction of functional antibodies, the magnitude of the antibody and T-cell response, as well as dose sparing. Furthermore, antigen-specific T cells were largely exhibited T helper 1 (Th1) phenotype.
The trial findings reveal a safety profile that is acceptable and comparable to previous studies utilizing comparable platform technologies. In the majority of study subjects, only mild reactogenicity was noted, and an adjuvanted vaccine slightly increased the intensity and frequency of such events.
Dr Glenn added, "Taken together, the adjuvanted, recombinant, full-length spike protein nanoparticle vaccine is a promising candidate that warrants rapid advancement into efficacy studies.”
The study also reveals the value of the second vaccine dose in the proposed two-dose regimen, as very high levels of antibodies, achieved warrant the logistics of a boosting visit. Another benefit is a liquid formulation of the vaccine that allows successful cold chain management with existing infrastructure.
The limitations of the trial were the length of time of safety observations and measured immune responses. It is clear that safety in the face of exposure to viral infection and immune response durability for SARs-CoV-2 vaccines will be of substantial interest.
Despite that limitation, these early results are encouraging, and another vaccine candidate has joined the growing armamentarium of vaccines against SARS-CoV-2. Further stages of clinical trials will show if NVX-CoV2373 will become viable as some other promising options.
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