Novavax said Thursday it has initiated its first phase 3 study to evaluate the efficacy, safety and immunogenicity of its COVID-19 vaccine candidate NVX-CoV2373. The trial, which is being conducted in the UK, is expected to enroll up to 10,000 individuals between the ages of 18 and 84 years, with and without relevant comorbidities, over the next 4 to 6 weeks.
“With a high level of SARS-CoV-2 transmission observed and expected to continue in the UK, we are optimistic that this pivotal phase 3 clinical trial will enroll quickly and provide a near-term view of NVX-CoV2373’s efficacy,” Gregory Glenn, who heads R&D at Novavax, said in the news release. He added that data from the late-stage study will support regulatory submissions for licensure in the UK, EU and other countries.
Half of the trial participants will receive two intramuscular injections of vaccine comprising 5 mcg of protein antigen plus 50 mcg of Matrix‑M adjuvant, administered 21 days apart, while the other half will be given a placebo. According to Novavax, the trial is designed to enroll at least 25% of participants over the age of 65, as well as to prioritize groups most affected by COVID-19, including racial and ethnic minorities. Moreover, up to 400 people in the study will also get a seasonal influenza vaccine as part of a sub-study to assess the potential benefit of co-administration.
The study has a two-pronged target, with one of the primary endpoints assessing first occurrence of PCR-confirmed “symptomatic” COVID-19, with onset at least 7 days after the second dose. The second main goal is the same, only it will look at first occurrence of “symptomatic moderate or severe” COVID-19 disease. Novavax said it plans to release its UK study protocol “in the coming days,” but indicated that “an interim analysis will be performed when 67% of the desired number of these cases has been reached.”
Larger US study planned
Meanwhile, planning is also underway for a larger, 30,000-person study in the US that will start enrolling in mid-October, while a smaller phase 2b trial in South Africa is ongoing.
Preliminary phase 1/2 data reported in August showed that NVX-CoV2373 triggered anti-spike IgG antibodies after a single dose in healthy adults, while neutralizing antibody responses were induced in all those who had been given a second dose. The recombinant coronavirus vaccine candidate was also generally well-tolerated and no serious adverse events were reported. Novavax started the phase 2 portion of the trial late last month.
The company recently signed a deal to supply the UK with 60 million doses of NVX-CoV2373, with the government there also agreeing to support the phase 3 study of the vaccine. In July, Novavax secured a $1.6-billion US contract to advance development of NVX CoV2373 and potentially deliver 100 million doses of the vaccine as early as late 2020.