Item 8.01 Other Events
On March 25, 2021, Icosavax, Inc. (the “Company”) announced topline interim results from its ongoing Phase 1/2 clinical trial of IVX-411, a virus-like particle (“VLP”) vaccine candidate displaying the SARS-CoV-2 receptor-binding domain.
The Company reported that while IVX-411 was immunogenic and well-tolerated in these initial topline data, the level of response was below the Company’s expectations given what it knows about VLPs, including from clinical studies in COVID-19 and from its own preclinical data. The Company remains committed to its novel VLP platform and vision for combination and pan-respiratory vaccines, indicating that it plans to investigate the potential causes of these discordant clinical results, including manufacture, shipment, and administration of the product.
As COVID-19 becomes endemic, it continues to be a strategic priority for the Company. With regard to the Company’s lead program in respiratory syncytial virus (“RSV”), the Company plans to report topline, interim data for IVX-121 in the second quarter of 2022, with the Phase 1 initiation of its first combination vaccine candidate, IVX-A12 against RSV and human metapneumovirus (hMPV), anticipated in the second half of 2022.
The ongoing Phase 1/2 clinical trial (IVX-411-01) is a randomized, observer-blinded, placebo-controlled study to evaluate the safety and immunogenicity of IVX-411 in SARS-CoV-2 naïve (N=84) and previously vaccinated (N=84) adults 18 to 69 years of age. Naïve subjects received two doses, given 28 days apart, of IVX-411 at 5, 25 or 125 micogram dosage levels or placebo, with or without adjuvant. Previously vaccinated subjects were boosted with a single dose of IVX-411 at 5, 25 or 125 micograms or placebo, with or without adjuvant, at three to six months following completion of primary licensed vaccine regimen (mRNA or adenoviral). A supplemental analysis was also conducted to assess whether sera from subjects immunized with IVX-411 neutralize the SARS-CoV-2 Omicron variant.
Safety – In this topline interim data, IVX-411 was generally safe and well-tolerated. Solicited local and systemic adverse events (“AEs”) were all mild or moderate, without dose-limiting reactogenicity. The most common local and systemic AEs were injection site tenderness, and headache and fatigue, respectively. There were no serious AEs deemed to be related to vaccine, AEs of special interest, or AEs leading to discontinuation. In the naïve setting, across the six dosage groups for IVX-411 with or without adjuvant, the proportion of subjects experiencing any systemic AE within seven days of any dose was 33-67%, versus 50% for placebo. In the booster setting, across the six dosage groups, 17-42% of subjects experienced any systemic AE within seven days of the booster dose, versus 25% for placebo.
Immunogenicity – In the naïve setting, a clear adjuvant effect on immunogenicity and a dose response were observed with IVX-411; however, the level of immune response in this initial data was comparable to or below the Human Convalescent Sera (“HCS”) control. At day 49 (or three weeks following the second dose), responses were up to 154 IU/mL across dosage groups in the live virus neutralization assay (HCS: 281 IU/mL), and up to 592 BAU/mL across groups in the spike IgG assay (HCS: 361 BAU/mL).
In previously vaccinated subjects, these initial data showed that IVX-411 boosted immunity following primary vaccination with an mRNA or adenovirus vaccine, and adjuvanted and unadjuvanted groups were generally similar. Pre- versus post-boost fold increases of up to 5x (599 IU/mL) for wild type virus were observed at day 28 post boost. For the Omicron variant, neutralizing antibody titers were up to 8-fold lower than observed for wild type virus in the same assay.
The Company anticipates providing an update on its end-to-end investigation after its completion.
Forward-Looking Statements
The Company cautions you that statements contained in this report regarding matters that are not historical facts are forward-looking statements. The forward-looking statements are based on the Company’s current beliefs and expectations and include but are not limited to: the possible safety and immunogenicity of IVX-411; the IVX-411-01, IVX-121 and IVX-A12 clinical trials (including projected timing of clinical trial milestones); IVX 411 development plans and the potential of the Company’s VLP technology. Actual results or developments may differ