A Study to Evaluate the Safety and Immunogenicity of IVX-A12 in Participants of 60 to 85 Years of Age

NCT05903183 | Completed Phase 2 Results DMC FDA Drug

• 1 other identifier: ICVX-12-201
• Study Type: interventional
• Target: 264
• Locations: 1 country
• Sites: 10

Brief Summary

The primary purpose of the study is to assess the safety, tolerability and immunogenicity of a bivalent respiratory syncytial virus (RSV)/human metapneumovirus (hMPV) virus-like particle (VLP) candidate vaccine (IVX-A12) compared to placebo, when administered as a single-dose regimen in healthy older adults 60 to 85 years of age.

Conditions

Healthy

Keywords

Respiratory syncytial virus (RSV); Human metapneumovirus (hMPV); Bivalent virus-like particle protein subunit vaccine

Outcome Measures

Primary Outcomes (8)

• Number of Participants With Solicited Local Adverse Reactions (ARs) and Systemic ARs

  Solicited local ARs include pain, tenderness, erythema, and swelling. Solicited systemic ARs include headache, chills, fatigue, myalgia, arthralgia, vomiting, diarrhea, and fever.

  From Day 0 to Day 6

• Number of Participants With Unsolicited Adverse Events

  An unsolicited AE is an AE that was not solicited using the post-vaccination diary and that was spontaneously communicated by a participant.

  From Day 0 to Day 28

• Model-adjusted Geometric Mean Titers (GMT) for RSV-A, RSV-B, hMPV-A, and hMPV-B-specific Neutralizing Antibodies (NAb)

  Model-adjusted GMT and corresponding 95% CI were derived from an analysis of covariance (ANCOVA) model of log2 titer at Day 28 with independent variables of log2 baseline titer, age group, and treatment group.

  At Day 28

• Model-adjusted Geometric Mean Concentrations (GMC) for RSV and hMPV Prefusion F Protein-specific IgG Antibodies (Ab)

  Model-adjusted GMC and corresponding 95% CI were derived from an analysis of covariance (ANCOVA) model of log2 concentration at Day 28 with independent variables of log2 baseline concentration, age group, and treatment group.

  At Day 28

• Percentage of Participants With a >=4-fold Increase in Serum RSV-A, RSV-B, hMPV-A, and hMPV-B-specific NAb Titers

  Proportion of participants with non-missing results at the specified visit achieving a 4-fold or greater increase in NAb titer versus baseline (Day 0).

  From Day 0 (pre-vaccination) up to Day 28 post-vaccination

• Percentage of Participants With >=4-fold Increase in RSV and hMPV-specific IgG Ab Concentration

  Proportion of participants with non-missing results at the specified visit achieving a 4-fold or greater increase in Ab concentration versus baseline (Day 0).

  From Day 0 (pre-vaccination) up to Day 28 post-vaccination

• Geometric Mean Fold Rise (GMFR) in Serum for RSV-A, RSV-B, hMPV-A, and hMPV-B-Specific NAb Titers

  GMFR is defined as the geometric mean of the ratio of NAb titer at specified timepoints after vaccination divided by baseline (Day 0) titer.

  From Day 0 (pre-vaccination) up to Day 28 post-vaccination

• Geometric Mean Fold Rise (GMFR) in Serum for RSV and hMPV Prefusion F Protein-specific IgG Ab Concentrations

  GMFR is defined as the geometric mean of the ratio of Ab concentration at specified timepoints after vaccination divided by baseline (Day 0) concentration.

  From Day 0 (pre-vaccination) up to Day 28 post-vaccination

Secondary Outcomes (11)

• Number of Participants With Serious Adverse Event (SAE), Medically-attended Adverse Events (MAAEs), and AEs Leading to Trial Withdrawal

  From Day 0 up to the end of study (up to Day 365)

• Number of Participants With Mild, Moderate, or Severe Lower Respiratory Tract Illness (LRTI) Caused by RSV and/or hMPV

  From Day 0 up to Day 365 (end of study)

• Number of Participants With Mild, Moderate, or Severe LRTI Cases Not Caused by RSV or hMPV

  From Day 0 up to Day 365 (end of study)

• Number of Participants With Clinically Significant Safety Laboratory Parameters

  At Screening, Days 0, 7 and 28

• Model-Adjusted GMTs for RSV-A, RSV-B, hMPV-A, and hMPV-B-specific NAb

  At Days 180 and 365

Study Arms (3)

IVX-A12 Vaccine Formulation 1

EXPERIMENTAL

Participants will receive a single dose of IVX-A12 intramuscular (IM) injection on Day 0.

Biological: IVX-A12

IVX-A12 Vaccine Formulation 2

EXPERIMENTAL

Participants will receive a single dose of IVX-A12 IM injection on Day 0.

Biological: IVX-A12

Placebo

PLACEBO COMPARATOR

Participants will receive a single dose of placebo IM injection on Day 0.

Biological: Placebo

Interventions

IVX-A12 BIOLOGICAL

IVX-A12 without adjuvant

IVX-A12 Vaccine Formulation 1

Placebo BIOLOGICAL

Diluent

Placebo

Eligibility Criteria

• Age: 60 Years - 85 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Male or female participants, who must be in stable health based on medical history, vital signs, physical examination, and laboratory evaluation prior to vaccination, in the investigator's clinical judgment
• Participants may have ongoing chronic conditions (comorbidities such as hypertension, congestive heart failure, chronic obstructive pulmonary disease, type 2 diabetes mellitus, hyperlipoproteinemia, or hypothyroidism) who are, in the investigator's opinion, medically compensated and without recent exacerbation within the prior 3 months
• Participants able to voluntarily give written informed consent and can comply with trial procedures including follow-up for approximately 12 months after vaccination
• Body mass index 17 to less than (\<) 40 kilograms per square meter (kg/m\^2) at screening
• Before randomization, female participants must be unable to conceive (example, menopausal, that is, 12 consecutive months without menstruation, hysterectomy, oophorectomy, etc.) and not intending to conceive by any method
• Participants must agree not to donate blood from the time of vaccination through 3 months after vaccination
• Participants must be willing to provide verifiable identification and have the means to be contacted and to contact the investigator or the site's staff during the entire clinical trial

You may not qualify if:

• Participants with moderate or severe liver disease, metastatic solid tumor, and acquired immunodeficiency syndrome (AIDS) are to be excluded. In addition, participants with underlying significant illness or condition(s) or ongoing treatment that, in the opinion of the investigator, could (i) interfere with the conduct of the trial, (ii) pose an unacceptable risk to the participant in this trial, (iii) interfere with the participant's ability to comply with the trial procedures or abide by the procedures
• Older adults who meet frail elderly criteria (older persons with medical, nutritional, cognitive, emotional, or activity impairments, as defined by the Dalhousie Clinical Frailty Score greater than or equal to \[\>=\]4)
• Prior receipt of any licensed or investigational RSV or hMPV vaccine within the past 12 months
• Prior receipt of another investigational medicinal product (IMP; trial drug, biologic, or device) not authorized for use in the United States of America (USA) and European Union within the past 3 months
• Laboratory-confirmed RSV or hMPV infection within 12 months prior to enrollment
• Currently enrolled or plan to participate in another clinical trial with an investigational agent (including licensed or unlicensed vaccine, drug, biologic, device, blood product, or medication) to be received during the trial period
• History of malignancy within 5 years before screening not in the following categories: (i) participants with squamous and basal cell carcinomas of the skin and carcinoma in situ of the cervix may be enrolled at the discretion of the investigator, (ii) participants with a history of malignancy within 5 years before screening, with minimal risk of recurrence per investigator's judgment, can be enrolled
• Acute illness, with or without fever at the time of planned vaccination
• History of hypersensitivity or serious adverse reactions to vaccines, such as anaphylaxis or angioedema, or any known allergies to any component of the IVX-121 and/or IVX-241 vaccine, or hypersensitivity to latex
• Abnormal function of the immune system resulting from clinical conditions including chronic administration of systemic corticosteroids (oral/intravenous/IM at a daily dose equivalent of greater than (\>) 20 milligram (mg) prednisone in a period of more than 14 days), or administration of immunosuppressive chemotherapy, biologics, or radiotherapy within the past 3 months prior to planned vaccination
• Participants who have received treatment with immunoglobulins or other biologics, such as immunosuppressive therapies expected to modify immune response to vaccination (including monoclonal antibodies \[MAbs\] for chronic underlying conditions) within the past 3 months prior to planned vaccination
• Trial personnel as an immediate family or household member
• For licensed vaccines:
• Receipt of licensed inactivated vaccines (including seasonal influenza vaccine) within 14 days prior to trial vaccine administration on Day 0, or licensed replicating vaccines such as ribonucleic acid (RNA) or live-attenuated virus vaccines within 30 days prior to Day 0
• Receipt of licensed vaccines is permitted after completion of the Day 28 visit

Sponsors & Collaborators

• Icosavax, Inc.: lead

Study Sites (10)

AMR Phoenix

Tempe, Arizona, 85281, United States

Location

Cenexel RCA

Hollywood, Florida, 33024, United States

Location

Clinical Research Atlanta

Stockbridge, Georgia, 30281, United States

Location

Velocity Clinical Research-Boise

Meridian, Idaho, 83642, United States

Location

ASR, LLC

Nampa, Idaho, 83587, United States

Location

Johnson City Clin-Trials (JCCT)

Lenexa, Kansas, 66219, United States

Location

AMR Lexington

Lexington, Kentucky, 40509, United States

Location

Velocity Clinical Research

Omaha, Nebraska, 68134, United States

Location

Rochester Clinical Research, Inc

Rochester, New York, 14609, United States

Location

PanAmerican Clinical Research

Brownsville, Texas, 78520, United States

Location

Related Links

• Redacted CSP
• Redacted SAP
• ICVX-12-201\_Redacted CSR\_synopsis

Results Point of Contact

• Title: Icosavax Clinical Operations
• Organization: Icosavax Inc.

clinops@icosavax.com

206-737-0085

Publication Agreements

• PI is Sponsor Employee: Yes
• Restrictive Agreement: No

Study Design

• Study Type: interventional
• Phase: phase 2
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: OTHER
• Intervention Model: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: June 5, 2023
• First Posted: June 15, 2023
• Study Start: May 15, 2023
• Primary Completion: June 5, 2023
• Study Completion: October 25, 2024
• Last Updated: December 5, 2025
• Results First Posted: December 5, 2025

Record last verified: 2025-11

Data Sharing

• IPD Sharing: Will not share

Locations

US (10)