Icosavax has reported topline interim data from the Phase I/II IVX-411-01 clinical trial of its virus-like particle (VLP) vaccine candidate, IVX-411, against Covid-19
IVX-411 displays the receptor-binding domain (RBD) of the SARS-CoV-2 virus, which causes Covid-19.
The observer-blinded, randomised, placebo-controlled trial underway is assessing the safety and immunogenicity of the vaccine in SARS-CoV-2 naïve and priorly inoculated adult subjects aged between 18 and 69 years.
Naïve subjects were given two 5ug, 25ug or 125ug doses of IVX-411 or placebo, with or without adjuvant, at a gap of 28 days.
Priorly vaccinated adults received boosting with a single dose of 5, 25 or 125ug IVX-411 or placebo, with or without adjuvant, at three to six months after the initial vaccine regimen with licensed vaccines.
The company also carried out an additional assessment to analyse if sera from participants who received IVX-411 could neutralise the Omicron variant of the virus.
According to the findings, IVX-411 was demonstrated to be safe and well-tolerated.
Mild or moderate solicited local and systemic adverse events (AEs) were observed in the trial with no dose-limiting reactogenicity observed.
A robust adjuvant effect on immunogenicity, as well as a dose-response, was observed on inoculating with IVX-41 in the naïve setting, but the immune response level was in line with or below the Human Convalescent Sera control.
In priorly inoculated participants, IVX-411 boosting was found to enhance immunity, and adjuvanted as well as unadjuvanted cohorts were reported to be similar.
A five-fold rise for wild type virus was noted at 28 days following the inoculation as against pre-boost.
Neutralising antibody titers for the Omicron variant were observed to be up to eight-fold less than for the wild type virus.
Icosavax chief medical officer Niranjan Kanesa-thasan said: “While IVX-411 was immunogenic and well-tolerated in these initial topline data, the level of response was below our expectations given what we know about VLPs, including from clinical studies in Covid-19 and from our own preclinical data.”