Encouraging results from respiratory diseases vaccine trial

shutterstock respiratory disease

A biopharmaceutical company developing vaccines against infectious diseases has announced positive results for people with life threatening respiratory diseases.

Icosavax says that in an interim phase 1/1b trial its vaccine IVX-121 has demonstrated robust immunological response to respiratory syncytial virus (RSV) in both young and older adult groups. The vaccine was generally tolerated with no vaccine-related serious adverse events (SAEs).

The company has an initial focus on life-threatening respiratory diseases and a vision of creating pan-respiratory vaccines for older adults said the topline interim results from its phase 1/1b clinical trial of IVX-121, a VLP displaying a prefusion stabilized RSV F antigen, in young and older adults were positive.

Multiple pathogen targets

Adam Simpson, chief executive officer of Icosavax said: “I’m delighted to share these topline, interim data from our Phase 1/1b trial in RSV, in which IVX-121 demonstrated a robust immunologic response in both young and older adult groups. Importantly, we believe these Phase 1/1b data provide initial validation of our underlying VLP technology. They also reaffirm our strategy to combine multiple pathogen targets in one vaccine.

“As planned, Icosavax will now progress development of IVX-121 combined with a human metapneumovirus (hMPV) VLP, as our IVX-A12 bivalent vaccine candidate. We believe IVX-A12 could be unique in providing protection against these two leading causes of pneumonia, each of which currently lack an approved vaccine.”

The phase 1/1b clinical trial of IVX-121 is a randomized, observer-blinded, placebo-controlled, multi-center study designed to evaluate the safety and immunogenicity of three dose levels of IVX-121, with and without aluminum hydroxide adjuvant, in healthy young and older adults.

The phase 1 part of the trial enrolled 90 healthy young adults aged 18 to 45. The phase 1b part of the trial enrolled 130 healthy older adults aged 60 to 75.

Subjects were administered a single dose of IVX-121 at one of three dose levels (25, 75, 250 mg), with or without aluminum hydroxide adjuvant, or placebo. The primary outcomes of the study were safety and immunogenicity up to 28 days post-vaccination; neutralizing antibodies to RSV-A and RSV-B were measured in international units (IU/mL) using the WHO international reference standard.

Vaccine candidate

The trial was intended to inform the dose of IVX-121 to be evaluated in combination with Icosavax’s hMPV VLP in an upcoming Phase 1 clinical trial of the company’s RSV/hMPV bivalent vaccine candidate IVX-A12.

In this phase 1/1b study, IVX-121 was generally well-tolerated across all dosage groups.

The company said that solicited local and systemic adverse events (AEs) were generally mild or moderate, without dose-limiting reactogenicity. In the older adult target population, across the six dosage groups for IVX-121 with or without adjuvant, the proportion of subjects experiencing any systemic AE within seven days was 11-33%, and similar to 21% for placebo.

The most common local and systemic AEs were injection site tenderness, headache and fatigue. There were no serious AEs related to vaccine, AEs of special interest, or AEs leading to discontinuation.


In this phase 1/1b study, IVX-121 induced a robust immune response in both young and older adult groups.

The data indicated a dose-independent response, including at the lowest non-adjuvanted dose (25 mg). No additional benefit from the aluminum hydroxide adjuvant was observed at any dosage level in either portion of the study. Geometric mean titers for RSV-A and RSV-B were in comparable ranges for both groups.

Niranjan Kanesa-thasan, chief medical officer of Icosavax said: “These topline interim data from our Phase 1/1b trial indicate that IVX-121 was generally well tolerated and elicited a strong and consistent response against RSV in healthy young and older adults. These data are particularly encouraging for the vulnerable older adult population with co-morbidities and increased risk for severe disease and hospitalization.”

He said the immunogenicity of IVX-121, even at very low microgram dosage levels, and its favorable tolerability to the highest dose level, makes it well suited to a combination vaccine approach.

Icosavax plans to submit an IND for IVX-A12 to the U.S. Food and Drug Administration (FDA) and thereafter initiate a phase 1 clinical trial in 2H 2022.

RSV remains one of the few major infectious diseases without a vaccine, and these data have the potential to meaningfully impact the treatment of RSV and may reduce the 360,000 hospitalizations and more than 24,000 deaths worldwide each year.

Newsletter Signup - Under Article / In Page

"*" indicates required fields

Subscribe to our newsletter to get the latest biotech news!

This field is for validation purposes and should be left unchanged.

Suggested Articles

Show More