Safety, Tolerability and Immunogenicity of a Maternal Respiratory Syncytial Virus (RSV) Vaccine (MKK900) in Healthy Adult Women (RSVVaccine)

A Phase 1, Randomized, Blinded, Active Controlled Clinical Trial to Evaluate the Safety, Tolerability and Immunogenicity of a Recombinant, Stabilized Pre-F Respiratory Syncytial Virus (RSV) Vaccine (MKK900), Non-adjuvanted, in Healthy Women Aged 18-49 Years

A Phase 1 study to evaluate safety, tolerability and immunogenicity a RSV vaccine in healthy women 18 to 49 years of age

Study Overview

• Status: Not yet recruiting
• Conditions: Respiratory Syncytial Virus (RSV)
• Intervention / Treatment: Biological: MKK900 60 µg; Biological: MKK900 120 µg; Biological: ABRYSVO®

Detailed Description

A Phase 1, randomized, blinded, active controlled clinical trial to evaluate the safety, tolerability and immunogenicity of a recombinant, stabilized pre-f respiratory syncytial virus (RSV) vaccine (MKK900), non-adjuvanted, in healthy women aged 18-49 years

Participants will be randomized in a 1:1:1 ratio to receive a single IM injection of one of low-dose MKK900, high-dose MKK900 or the active control (ABRYSVO).

Participants will be immunized on day 1 and safety and immunogenicity will be evaluated at day 8, 31 and 91. Safety will also be assessed at day 181.

• Study Type: Interventional
• Enrollment (Estimated): 120
• Phase: Phase 1

Contacts and Locations

• Study Contact: Name: Zhou (Jo) Jiang; Phone Number: +1515-598-6266; Email: zhou.jiang@maxvax.cn

Study Locations

• Australia
  • New South Wales
    • Botany, New South Wales, Australia, 2019
      • Emeritus Research Sydney
      • Contact: Dr Ronald Lok Yeung Mak; Phone Number: +610289648186; Email: ronaldmak@emeritusresearch.com
      • Principal Investigator: Dr Ronald Lok Yeung Mak
  • Victoria
    • Camberwell, Victoria, Australia, 3124
      • Emeritus Research Camberwell
      • Contact: Dr Ri Peng (Justin) Tan; Phone Number: +610395096166; Email: justintan@emeritusresearch.com
      • Principal Investigator: Dr Ri Peng (Justin) Tan

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

1. Adult females 18-49 years old on the day of vaccination.
2. Generally healthy, as established by medical history and clinical examination before vaccination and absence of unresolved acute disease or acute exacerbation of chronic disease.
3. Intent to reside in the area of the study site for the throughout the study visits and also available for phone follow ups after vaccination.
4. Signing an Informed Consent Form indicating that the purpose, procedures and potential risks and benefits of the study have been explained including an opportunity to ask questions.
5. Females must not be of childbearing potential OR those who are of childbearing potential must be non-pregnant and non-lactating and willing to use acceptable, highly effective methods of contraception from 28 days prior to vaccination on Day -1 through to 90 days after vaccination. Females must also agree not to donate ova from the first dose of the study vaccine until at least 90 days after vaccination.

Exclusion Criteria:

1. Recent RSV exposure/vaccination: History of RSV infection within 6 months or prior RSV vaccination.
2. Pregnancy/lactation: Pregnant, breastfeeding, or planning pregnancy within 90 days post-vaccination.
3. Recent investigational products: Received any investigational product within 30 days or plans study participation during this trial.
4. Recent vaccines: Live vaccine within 30 days or any other vaccine within 14 days before study vaccination, or planned vaccination within 3 months after.
5. Blood products: Received immunoglobulins or blood products within 6 months.
6. Recent blood donation: Donation/loss of >450 mL of blood or components within 14 days of Day 1.
7. Active illness: Acute illness or acute flare of chronic disease within 3 days before vaccination.
8. Vaccine allergies: Allergy to vaccine components (especially aminoglycosides) or severe reactions to past vaccines.
9. Neurological conditions: History of seizures, epilepsy, encephalopathy, or significant neurological disorders.
10. Mental health concerns: Any mental illness that may affect study compliance or AE reporting.
11. Malignancy: Active cancer or cancer within past 5 years (except adequately treated skin or cervical lesions).
12. Splenic issues: Asplenia, functional asplenia, or splenectomy.
13. Immunodeficiency/autoimmune disease: Congenital/acquired immunodeficiency or autoimmune diseases per Investigator judgement.
14. Immunosuppressive therapy: Systemic immunosuppressants (e.g., prolonged steroids) within 3 months; inhaled/topical steroids allowed.
15. Severe chronic diseases: Severe cardiac, pulmonary, hepatic, renal disease, or diabetes.
16. Coagulation issues: History of thrombocytopenia or bleeding disorders contraindicating IM injection.
17. Fever/infection: Fever >38°C or active systemic infection within 7 days of vaccination.
18. Hypertension: Abnormal or uncontrolled high blood pressure at screening (≥140/90 mmHg).
19. Known or suspected infection with HBV, HCV, or HIV.
20. Alcohol or drug abuse, including regular alcohol intake of >14 drinks/week or >4 drinks/day.
21. Positive drug screen (amphetamines, barbiturates, benzodiazepines, cocaine, THC, methadone, methamphetamine, opiates, PCP, tricyclic antidepressants) or positive alcohol breath test at Screening or Day -1.
22. Inability to assess injection site due to tattoos or skin conditions on both deltoids.
23. Study site employees involved in the protocol or with access to study data.
24. Any other condition that may impact participant safety or interfere with study assessments, as judged by the Investigator.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: MKK900 60 µg; stabilized pre-F antigen from Type A RSV	Biological: MKK900 60 µg; Unit Dose Strength: The 60-μg dose vial will have a concentration of 120 μg/mL (0.5 mL injection volume) Route of Administration : Intramuscular Injection
Experimental: MKK900 120 µg; stabilized pre-F antigen from Type A RSV	Biological: MKK900 120 µg; Unit Dose Strength: The 120-μg dose vial will have a concentration of 240 μg/mL (0.5 mL injection volume). Route of Administration : Intramuscular Injection
Active Comparator: ABRYSVO	Biological: ABRYSVO®; Dose Formulation: Vial of Lyophilized Antigen Component (sterile white power) that is reconstituted at the time of use with a Sterile Water Diluent Component. Unit Dose Strength: 120 µg of RSV stabilized pre-fusion F proteins (60 µg RSV pre-F A and 60 µg RSV pre-F B) per 0.5 mL. Route of Administration: Intramuscular injection

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Frequency of solicited local and systemic adverse events (AEs)	during the 7 days following vaccination
Frequency of unsolicited adverse events AEs	during the 30 days following vaccination
Frequency of serious adverse events (SAEs)	up to 180 days after vaccine administration

Secondary Outcome Measures

Outcome Measure	Time Frame
Geometric mean titers (GMTs) of neutralizing antibodies against RSV types A and B	Day 7, Day 30, and Day 90 post-vaccination.
Geometric mean fold rise (GMFR) of neutralizing antibodies against RSV types A and B	Day 7, Day 30, and Day 90 post-vaccination.
Seroresponse rate of neutralizing antibodies against RSV types A and B	Day 7, Day 30, and Day 90 post-vaccination.

Collaborators and Investigators

• Sponsor: MAXVAX Biotechnology Limited Liability Company

Study record dates

Study Major Dates

• Study Start (Estimated): April 1, 2026
• Primary Completion (Estimated): April 30, 2026
• Study Completion (Estimated): January 15, 2027

Study Registration Dates

• First Submitted: March 10, 2026
• First Submitted That Met QC Criteria: March 19, 2026
• First Posted (Actual): March 25, 2026

Study Record Updates

• Last Update Posted (Actual): March 25, 2026
• Last Update Submitted That Met QC Criteria: March 19, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: abrysvo
• Other Study ID Numbers: MKKCT-900-004

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No