A Study of IVX-A12 in Adults Participants

A Phase 2, Randomized, Modified Double-Blind, Active Controlled Study to Characterize the Safety and Immunogenicity of IVX-A12 in Adults 60 Years of Age and Older

The primary purpose of this study is to assess the immunogenicity and safety of IVX-A12 in adults 60 years of age and older.

Study Overview

• Status: Completed
• Conditions: Healthy Participants
• Intervention / Treatment: Biological: IVX-A12; Biological: Licensed RSV Vaccine

Detailed Description

This is a randomized, modified double-blind, active controlled study to characterize the immunogenicity and safety of IVX-A12.

Approximately 140 participants will be randomized in a 1:1 ratio to receive IVX-A12 (approximately 70) or licensed respiratory syncytial virus (RSV) vaccine (AREXVY) (approximately 70).

The study is planned to be conducted at approximately 5 sites in the United States. The duration of each participant's involvement in the study will be approximately 6 months following administration of study vaccination.

• Study Type: Interventional
• Enrollment (Actual): 143
• Phase: Phase 2

Contacts and Locations

Study Locations

• United States
  • California
    • Anaheim, California, United States, 92801
      • Icosavax Investigational Site US022
    • Rolling Hills Estates, California, United States, 90274
      • Icosavax Investigational Site US021
  • Florida
    • Hollywood, Florida, United States, 33024
      • Icosavax Investigational Site US002
  • Kansas
    • Lenexa, Kansas, United States, 66219
      • Icosavax Investigational Site US011
  • South Carolina
    • North Charleston, South Carolina, United States, 29405
      • Icosavax Investigational Site US016

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

1. Adults >=60 years of age at the time of signing informed consent.
2. Participants who are medically stable according to the judgment of the Investigator.
3. Able to understand and comply with study requirements/procedures based on the assessment of the Investigator.
4. Capable of giving signed informed consent.

Exclusion Criteria:

1. Acute (time-limited) or febrile (temperature >=38.0 °C [100.4 ºF]) illness/infection within 3 days of planned dosing.
2. History of a clinically significant bleeding disorder (e.g., factor deficiency, coagulopathy, or platelet disorder), or prior history of significant bleeding or bruising following IM injections or venipuncture.
3. History of hypersensitivity to any component of the study vaccination.
4. History of severe adverse reaction associated with a vaccine and/or severe allergic reaction (e.g., anaphylaxis).
5. Known or suspected congenital or acquired immunodeficiency.
6. Known or suspected autoimmune condition as determined by history and/or physical examination.
7. History of Guillain-Barré syndrome or any other demyelinating condition.
8. History of malignancy other than treated non-melanoma skin cancers or locally-treated cervical cancer in previous 5 years.
9. Any condition that may significantly increase the risk to the participant because of participation in the study, impact the participant's ability to participate in the study, or impair the interpretation of the study data.
10. Receipt of any licensed or investigational RSV and/or Human metapneumovirus (hMPV) vaccine any time prior to administration of study intervention.
11. Receipt of any licensed vaccine (other than licensed influenza or COVID-19 vaccines) within 28 days prior to or expected receipt within 28 days after administration of study intervention. Licensed influenza or COVID-19 vaccines are permitted beginning greater than (>)14 days prior to and >14 days after administration of study intervention.
12. Receipt of immunoglobulin or blood products within 3 months prior to administration of study intervention or expected receipt during the study.
13. Receipt of immune-modifying drugs or immunosuppressive therapy, such as anti-cancer chemotherapy or radiation therapy within 6 months prior to enrollment (or expected receipt during study), or long-term systemic corticosteroid therapy (prednisolone or equivalent at a dose of >=20 mg daily or every other day for more than 2 consecutive weeks) within 6 months prior to study intervention or anticipated receipt during study.
14. Participation in another study or receiving interventional study investigational medicinal product (IMP), in the preceding 28 days or expected receipt of another study intervention (or participation in another study) during the period of study follow-up.
15. Employees of the Sponsor involved in planning, executing, supervising, or reviewing the IVX-A12 program, clinical study site staff, or any other individuals involved with the conduct of the study, or immediate family members of such individuals.
16. Alcohol or substance abuse that, in the opinion of the Investigator, might interfere with the study conduct or completion.
17. Deprived of freedom by an administrative or court order, or in emergency setting, or hospitalized involuntarily.
18. Judgment by the Investigator that the participant should not participate in the study if the participant is unlikely to comply with study procedures, restrictions, and requirements.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: IVX-A12 Vaccine; Participants will receive a single dose of IVX-A12, 300 micrograms (mcg), intramuscular (IM) injection on Day 1.	Biological: IVX-A12; IVX-A12 IM injection.
Active Comparator: Licensed RSV Vaccine; Participants will receive a single dose of licensed RSV vaccine (AREXVY) IM injection on Day 1.	Biological: Licensed RSV Vaccine; Licensed RSV Vaccine (AREXVY) IM injection.; Other Names: AREXVY

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Model-adjusted Geometric Mean Concentration (GMC) for RSV/A Neutralizing Antibodies (NAb)	Model-adjusted GMCs and 95% CIs were derived using an ANCOVA model for log2 nAb responses at Day 29 with independent variables of study intervention, log2 baseline response, and age group. Measured values were calculated as the anti-logarithm transformation of the least square means and 95% CIs from the model.	At Day 29
Geometric Mean Fold Rise (GMFR) in RSV/A NAb Concentrations	The GMFR was calculated as the anti-logarithm of Σ(log2 transformed (post-baseline response/baseline response)/n), where n is the number of participants with non-missing response information at baseline and at the post-baseline timepoint.	From baseline up to Day 29
Number of Participants With Immediate Unsolicited Adverse Events (AEs)	Immediate AEs were defined as having an onset time within 30 minutes after study vaccination.	Within the 30 minutes after vaccination on Day 1
Number of Participants With Injection Site and Systemic Solicited Adverse Reactions (ARs)	The injection site solicited ARs included predefined injection site pain, injection site erythema/redness, and injection site swelling. The systemic solicited ARs included predefined fever, chills, headache, myalgia (muscle aches and pains), and fatigue (physical or mental tiredness).	Day 1 through Day 8
Number of Participants With Unsolicited Adverse Events (AEs)	The unsolicited AEs were any AE other than predefined solicited AEs.	Day 1 through Day 29
Number of Participants With Serious Adverse Events (SAEs), Medically-attended Adverse Events (MAAEs), and Adverse Events of Special Interests (AESIs)	A SAE defined as an AE that occurred during any phase of study and met one or more of following criteria: resulted in death; was immediately life-threatening; required in-patient hospitalization or led to prolongation of existing hospitalization; resulted in persistent or significant disability or incapacity; was a congenital anomaly or birth defect; or was considered an important medical event that might have jeopardized the participant or required medical intervention to prevent one of aforementioned outcomes. MAAEs defined as AEs leading to medically-attended visits that were not routine visits for physical examination or vaccination, such as an emergency room visit, or an otherwise unscheduled visit to or from medical personnel (medical doctor) for any reason. An AESI was an event of scientific and medical interest, specific to further understanding of safety profile of investigational vaccine and required close monitoring and rapid communication by Investigators to the Sponsor.	Day 1 through Day 29

Collaborators and Investigators

• Sponsor: Icosavax, Inc.

Study record dates

Study Major Dates

• Study Start (Actual): June 10, 2024
• Primary Completion (Actual): July 17, 2024
• Study Completion (Actual): December 19, 2024

Study Registration Dates

• First Submitted: June 25, 2024
• First Submitted That Met QC Criteria: June 25, 2024
• First Posted (Actual): July 1, 2024

Study Record Updates

• Last Update Posted (Estimated): August 26, 2025
• Last Update Submitted That Met QC Criteria: August 22, 2025
• Last Verified: July 1, 2025

More Information

Terms related to this study

• Keywords: Respiratory syncytial virus (RSV); Human metapneumovirus (hMPV)
• Additional Relevant MeSH Terms: arexvy
• Other Study ID Numbers: ICVX-12-202

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No