Icosavax Shifts Focus On Bivalent Strategy For COVID-19 Vaccine Candidate After Antigen Instability Issues

Icosavax Inc ICVX announced the results of an end-to-end drug product investigation of IVX-411, a VLP vaccine candidate displaying the SARS-CoV-2 receptor-binding domain (RBD).
The investigation followed the company's Phase 1/2 topline interim data results.
The immunologic response observed for IVX-411 was inconsistent with expectations based on known data for the company's platform and VLP technology.
The investigation involved a review of in vitro antigen stability and characterization and in vivo potency, as well as a review of data and protocols relating to the transport, storage, and administration.
Also Read: Icosavax Shares Plummet Following Interim Results From Initial-Stage RSV Vaccine Study.
Results of the investigation confirmed the company's initial hypothesis that the reduced potency observed for IVX-411 was antigen-specific.
No similar pattern of instability has been seen in data to date in other Icosavax vaccine candidates, including for RSV and hMPV.
The company now focuses on a bivalent strategy for COVID-19 candidate development displaying computationally engineered RBD antigens. Candidate selection is expected in 2023.
Price Action: ICVX shares closed at $7.72 on Thursday.