Phase 2
N=72
A Trial Evaluating the Safety and Immunogenicity of 3 COVID-19 SARS-CoV-2 RNA Vaccines in Healthy Adults
COVID-19 · SARS-CoV-2 Infection · Corona Virus Infection
Bottom Line
View on ClinicalTrials.gov: NCT05037097 ↗Enrolled (actual)
72
Serious AEs
2.8%
Results posted
Oct 2025
Primary outcome: Primary: Number of Participants Reporting Solicited Local or Systemic Adverse Events (AEs) — 3; 4; 3; 5 Participants
Study Design & Population
- Study type
- Interventional
- Phase
- Phase 2
- Interventions
- ARCT-165 (Biological); ARCT-154 (Biological); ARCT-021 (Biological)
- Age
- Adult, Older Adult · 21+ yrs
- Sex
- All
- Sponsor
- Arcturus Therapeutics, Inc.
- Primary completion
- Dec 2023
Outcome Measures
| Outcome | Result | p-value |
|---|---|---|
| PRIMARY Number of Participants Reporting Solicited Local or Systemic Adverse Events (AEs) |
3; 4; 3; 5; 10; 12 | — |
| PRIMARY Number of Participants Reporting Unsolicited AEs |
3; 3; 2; 4; 15; 9 | — |
| PRIMARY Number of Participants Reporting Medically Attended Adverse Events (MAAEs), AEs Leading to Discontinuation From Study Vaccine/Study Withdrawal, or Serious Adverse Events (SAEs) |
0; 1; 0; 1; 3; 2 | — |
| PRIMARY Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) Serum Neutralizing Antibody Levels, Expressed as Geometric Mean Concentration (GMC) |
8; 8; 12; 421; 455; 87 | — |
| PRIMARY SARS-CoV-2 Serum Neutralizing Antibody Levels, Expressed as GMC |
14; 14; 14; 402; 442; 38 | — |
| PRIMARY SARS-CoV-2 Serum Neutralizing Antibody Levels, Expressed as Geometric Mean Fold Rise (GMFR) |
16; 22; 28; 4.6; 1.0; 2.2 | — |
| PRIMARY SARS-CoV-2 Serum Neutralizing Antibody Levels, Expressed as GMFR |
14; 34; 25; 1.2; 2.3; 1.2 | — |
| PRIMARY Number of Participants Achieving Greater Than or Equal to 4-fold Rise From Before Vaccination in SARS-CoV-2 Serum Neutralizing Antibody Levels (Pseudoviral D614G Variant) |
11; 11; 10; 1; 0; 2 | — |
| PRIMARY Number of Participants Achieving Greater Than or Equal to 4-fold Rise From Before Vaccination in SARS-CoV-2 Serum Neutralizing Antibody Levels (Pseudoviral B.1.351 [Beta] Variant) |
11; 11; 10; 0; 1; 0 | — |
| PRIMARY GMC Ratio (ARCT-165 vs ARCT-154 and ARCT-021 vs ARCT-154) |
0.41; 0.58; 1.38; 0.35; 1.01; 0.41 | — |
| PRIMARY GMC Ratio (ARCT-021 vs ARCT-165 Cohorts A1 and B) |
0.70; 4.00; 0.79; 0.48; 1.06; 0.70 | — |
| PRIMARY SARS-CoV-2 Full-length Spike and Receptor-binding Domain (RBD) Binding Antibody Levels, Expressed as GMCs |
0.0; 0.1; 0.1; 34; 29; 9 | — |
| PRIMARY Changes in SARS-CoV-2 Full-length Spike and RBD Binding Antibody Levels, Expressed as GMFRs |
129; 286; 110; 4.1; 4.9; 231 | — |
| PRIMARY Number of Participants Achieving Greater Than or Equal to 4-fold Rise From Before Vaccination in SARS-CoV-2 Full-length Spike and RBD Binding Antibody Levels |
4; 2; 4; 3; 9; 4 | — |
Summary
This is a Phase 1/2, randomized, observer-blind study in healthy adults. The study will evaluate the safety, reactogenicity, and immunogenicity of 3 SARS-CoV-2 self-amplifying RNA vaccine candidates against COVID-19 in adults previously vaccinated and not previously vaccinated against SARS-CoV-2.
Eligibility Criteria
Inclusion Criteria
Individuals who:
- Are able to provide consent
- Agree to comply with all study visits and procedures
- Are willing and able to adhere to study restrictions
- Are sexually active and willing to adhere to contraceptive requirements
- Are male, female, or transgender ≥21 to ≤80 years of age
- For the previously vaccinated groups only, received 2 doses of SARS-CoV-2 vaccine 5 months or longer prior to study enrollment
Exclusion Criteria
Individuals who:
- For the unvaccinated groups only, previously received any investigational or authorized MERS-CoV, SARS-CoV, and SARS-CoV-2 vaccines (including ARCT-021)
- For the previously vaccinated groups only, previously received BNT162b2 but have not received 2 doses within at least 5 months prior to study enrollment
- Are planning to receive other COVID-19 vaccines during the study period
- Recently received other vaccines
- Have a fever or are feeling sick close to the time of the first study vaccination
- Have a known history of COVID-19 disease or asymptomatic SARS-CoV-2 infection
- Are pregnant or breastfeeding
- Have had a severe reaction to previous vaccines
- Have a severe or uncontrolled disease(s) that may interfere with the interpretation of the study
- Have some respiratory diseases
- Have some significant heart diseases
- Have some neurological conditions
- Have sickle cell disease or some other blood disorders
- Have had a major surgery within the past 6 months
- Have a history of chronic liver disease
- Have a history of autoimmune disease or immunodeficiency
- Have received allergy injections, interferon, immunomodulators, cytotoxic drugs or other similar toxic drugs.
- Have received blood products
- Have a positive test for hepatitis B or C or human immunodeficiency virus
- Have uncontrolled hypertension
- Have had cancer except for cancers that were treated and that have low risk of returning
- Are obese
- Are Investigator site staff members, employees of Arcturus or the contract research organization (CRO) directly involved in the conduct of the study, or site staff members otherwise supervised by the Investigator or immediate family members of any of the previously mentioned individuals
Data sourced from ClinicalTrials.gov (NCT05037097). Outcome figures and adverse-event rates are extracted automatically from the registry's posted results and are provided for clinician reference, not as a substitute for the primary publication.