Icosavax Shares Crater as COVID-19 Vaccine Disappoints


Seattle-based Icosavax’s stock plunged 50% after the company reported topline interim data from its ongoing Phase I/II COVID-19 vaccine trial. 

The safety of the company’s virus-like particles (VLP) vaccine seemed fine, with any local and systemic adverse events being mild or moderate. The most common side effects were injection site tenderness, headache and fatigue, with no serious adverse events. 

It was around immunogenicity that the vaccine seemed to disappoint. Although there was a clear adjuvant effect — a compound added to the vaccine to further stimulate the nervous system — and there was a dose-response, the immune response seen in this interim analysis was comparable or even below the Human Convalescent Sera (HCS) control.  

That is to say, people who had been infected with COVID-19 had a better immune response than people who had received the Icosavax vaccine. This is a lower efficacy compared to the mRNA vaccines from Moderna and PfizerBioNTech. At day 49 after the second dose, immune responses were up to 154 IU/mL across dosage groups in the company’s live virus neutralization assay and up to 592 BAU/mL across all groups in the spike IgG assay. 

The data in people who had been previously vaccinated demonstrated the vaccine increased immunity after the primary vaccination with an mRNA or adenovirus vaccine. The groups with the adjuvant and without the adjuvant were generally alike. 

“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,” said Dr. Niranjan Kanesa-thasan, Icosavax’s chief medical officer. 

Adam Simpson, the company’s chief executive officer, assured investors that the company was committed to its VLP platform and its efforts and “vision” for combination and pan-respiratory vaccines.  

“We plan to investigate the potential causes of these discordant clinical results, including manufacture, shipment, and administration of the product,” Simpson said. “As COVID-19 becomes endemic, it continues to be a strategic priority for Icosavax. With regard to our lead program in RSV, we look forward to sharing topline, interim data for IVX-121 in 2Q 2022, with the Phase I initiation of our first combination vaccine candidate, IVX-A12 against RSV and human metapneumovirus (hMPV), anticipated in 2H 2022.” 

Icosavax’s VLP platform technology allows for multivalent, particle-based display of complex viral antigens. This is believed to induce broad, robust and durable protection against which viruses are targeted. In addition to vaccines for COVID-19, RSV and hMPV, it has an emerging program in influenza. 

Icosavax was established in 2017 based on VLP technology from the Institute for Protein Design at the University of Washington. 

In its January 7 pipeline update, the company noted it had exercised its option for a non-exclusive patent license granted by the University of Washington and the Department of Health and Human Services (HHS) for use with its VLP platform. As of December 21, 2021, the company had $281 million in cash, which it expected to fund operations to at least 2024. 

Icosavax went public in June 2021 and raised more than $180 million.

Source: BioSpace

Investors were initially excited about the company’s platform because the vaccines are designed to target a part of the virus that is less likely to mutate. The rapid stock drop suggests investors are now wary of the company’s entire technology platform, not just the COVID-19 vaccine, which would have had to display dazzling results to compete in an increasingly crowded marketplace. However, there’s quite a bit riding on the value of the company’s RSV and hMPV programs. 

In a November 2020 interview with BioSpace, Simpson said, “Our VLP technology should also have the advantages of scalable manufacturing, easily maintainable temperatures in the supply chain and, we expect, sustained durability.” 

Even so, this is true only if it demonstrates effectiveness. 

BioSpace source: