The ARCT-154 Self-Amplifying RNA Vaccine Efficacy Study (ARCT-154-01)

Phase 2

Completed

• Conditions: COVID-19 Vaccines
• Interventions: Biological: ARCT-154 Self-Amplifying RNA SARS-CoV-2 Vaccine; Other: Placebo (normal saline); Biological: Astra Zeneca COVID-19 vaccine

• Registration Number: NCT05012943
• Lead Sponsor: Vinbiocare Biotechnology Joint Stock Company

Brief Summary

This is a Phase 1/2/3, randomized, placebo-controlled, observer-blind study designed to evaluate the safety, immunogenicity and efficacy of ARCT-154 in adult participants to be enrolled in Vietnam.

This study consists of four parts:

Part 1 (Phase 1) will evaluate the safety of the study vaccines in 100 healthy individuals.

Part 2 (Phase 2) will evaluate the safety and immunogenicity of the study vaccines in 300 healthy individuals.

Part 3 (Phase 3a) will evaluate the safety, immunogenicity, and efficacy of the study vaccines in 600 individuals with and without underlying medical conditions.

Part 4 (Phase 3b) will evaluate the safety and efficacy of the study vaccines in 16,000 individuals with and without underlying medical conditions.

Part 5 (Phase 3c) will evaluate the safety and non-inferiority in immunogenicity of ARCT-154 vaccine vs. Astra Zeneca COVID-19 vaccine (ChAdOx1 nCoV-19) in 2400 individuals with and without underlying medical conditions.

In Phase 1, healthy individuals 18 to \< 60 years of age will be enrolled. In Phase 2, 3a, and 3b, individuals 18 years of age and older will be enrolled including individuals with underlying medical conditions that put them at higher risk of complications of COVID-19 disease.

Phase 1, Phase 2, Phase 3a and Phase 3b participants will be randomly assigned to a study group that will receive up to 2 vaccination series. Each vaccination series comprises two vaccinations at 28-day intervals: an initial vaccination series with vaccinations on Day 1 and Day 29 and an additional vaccination series around 2 months after the first series (on Day 92 and 120).

Participants of Phase 2, 3a who received 2 doses of ARCT-154 vaccine will be rerandomized to receive either dose 3 of ARCT-154 on Day 92 plus placebo on Day 120 or placebo on Day 92 plus placebo on Day 120.

For Phase 1, Phase 3b and participants in Phase 2 and 3a that received placebo in the first vaccination series, the participants will be switched over to the opposite vaccine in the second series.

There is no second vaccination series for Phase 3c as all participants receive active vaccine in the initial series.

Detailed Description

Phase 1 will enroll 100 healthy participants that are randomly assigned 3:1 to receive ARCT-154 or placebo (75:25) for the initial series of vaccinations.

In Phase 2, 300 participants will be randomly assigned 3:1 to receive ARCT-154 or placebo for the initial series of vaccinations. Participants that received ARCT-154 in the initial series will be rerandomized 3:1 to receive ARCT or placebo on Day 92 followed by placebo on Day 120.

In Phase 3a, 600 participants will be randomly assigned 3:1 to receive ARCT-154 or placebo for the initial series of vaccinations. Participants that received ARCT-154 in the initial series will be rerandomized 3:1 to receive ARCT or placebo on Day 92 followed by placebo on Day 120.

In Phase 3b, \~16,000 participants will be randomly assigned 1:1 to receive ARCT-154 or placebo for the initial series of vaccinations.

In Phase 3c, \~2,400 participants will be randomly assigned 1:1 to receive ARCT-154 or Astra Zeneca COVID-19 vaccine. Blood samples will be collected and reserved for Immunogenicity evaluation for the first 1500 participants (3c-1) and assays for immunogenicity evaluation will be performed for the first 800 participants.

Phase 1 participants must be \<60 years of age and healthy. Phase 2, 3a, and 3b and 3c participants will include elderly (≥60 years) and those with comorbidities.

For Phase 2, 3a, 3b and 3c, prior to randomization, participants will be stratified by age (\< 60 or ≥ 60 years of age) and for participants \< 60 years of age by risk of severe COVID 19. Participants will be followed up for approximately 1 year after completion of the initial vaccination series.

An independent Data and Safety Monitoring Board (DSMB) will perform ongoing review of blinded and unblinded data.

An independent blinded adjudication committee will adjudicate all suspected COVID-19 cases to determine if they meet the primary endpoint requirements.

Study Timeline

• Study First Submitted: 2021-08-13
• Study First Submitted QC: 2021-08-13
• Study Start: 2021-08-15
• Study First Posted: 2021-08-19
• Primary Completion: 2023-01-18
• Study Completion: 2023-01-18
• Status Verified: 2023-10
• Last Update Submitted: 2023-10-13
• Last Update Posted: 2023-10-16

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 19494

Inclusion Criteria

Individuals who:

1. are able to provide consent
2. agree to comply with all study visits and procedures
3. are of childbearing potential and sexually active must be willing to adhere to contraceptive requirements
4. are male or female ≥18 years of age (or, for Phase 1, 18 to < 60 years of age)
5. are at higher risk of developing COVID-19 based on where they work or live

Exclusion Criteria

Individuals who:

1. Significant infection or other acute illness, including body temperature >100.4°F (>38.0°C) on the day prior to or Day 1. Participants meeting this criterion may be rescheduled within the relevant window periods. Afebrile participants with minor illnesses can be enrolled at the discretion of the investigator.

2. Pregnant or breastfeeding.

3. Known history of COVID-19 (asymptomatic SARS-CoV-2 infection and/or nucleocapsid positive test is not exclusionary).

4. Close contact with a person known to be SARS-CoV-2 positive or with a clinical diagnosis of COVID-19 within 7 days prior to enrollment. Participants meeting this criterion who remain asymptomatic for 7 days may be rescheduled for enrollment within the relevant windows.

5. Known history of anaphylaxis, urticaria, or other significant adverse reaction to the vaccine or its excipients.

6. Known history of anaphylaxis to other vaccines.

7. Bleeding disorder considered a contraindication to intramuscular (IM) injection or phlebotomy.

8. Immunosuppressive or immunodeficient state, asplenia, recurrent severe infections, or known to be HIV positive.

9. An underlying clinically significant acute or chronic medical condition or physical examination findings for which, in the opinion of the investigator, participation would not be in the best interest of the participant (eg, compromise the well-being) or that could prevent, limit, or confound the protocol-specified assessments.

   Prior/Concomitant Therapy

10. Has previously received investigational or approved MERS-CoV, SARS-CoV, SARS-CoV-2 vaccines or who have plans to receive off-study COVID-19 vaccines.

11. Has received a live replicating vaccine within 28 days prior to each study vaccination or a licensed inactivated or non-replicating vaccine within 14 days prior to first study vaccination.

12. Has received treatment with immunosuppressive therapy, including cytotoxic agents or systemic corticosteroids, eg, for cancer or an autoimmune disease, within 6 months prior to Screening, or planned receipt throughout the study. If systemic corticosteroids have been administered short term (<14 days) for treatment of an acute illness, participants should not be enrolled into the study until corticosteroid therapy has been discontinued for at least 28 days prior to first study vaccine administration. Inhaled/nebulized, intra-articular, intrabursal, or topical (skin or eyes) corticosteroids are permitted.

13. Has received systemic immunoglobulins or blood products within 3 months prior to first study vaccine administration or plans to receive such products during the study.

    Other Exclusions

14. Demonstrated inability to comply with the study procedures.

15. Investigator site staff members, employees of the Sponsor or the 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.

16. Other restrictions apply to Phase 1 participants to ensure they are healthy.

Additional Exclusion Criteria for Phase 3c Participants Only:

No contraindications (as specified in the prescribing information) to receiving the ChAdOx1 vaccine.

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
ARCT-154	ARCT-154 Self-Amplifying RNA SARS-CoV-2 Vaccine	Each participant is planned to receive a two-dose vaccination series of ARCT-154 at a dose of 5 µg with 28 day interval in the first vaccination series.
Placebo	Placebo (normal saline)	Each participant is planned to receive a two-dose vaccination series of placebo (normal saline) with 28 day interval in the first vaccination series.
Astra Zeneca COVID-19 vaccine	Astra Zeneca COVID-19 vaccine	Each participant is planned to receive a two-dose vaccination series of Astra Zeneca COVID-19 vaccine with 28 day interval in the first vaccination series.

Primary Outcome Measures

Name	Time	Method
Percentage of participants reporting adverse events	From Dose 1 through 1 month after Dose 2	As elicited by investigational site staff
Number of participants with a first occurrence of COVID-19	Day 37 to Day 92 (to evaluate vaccine efficacy 7 days after dose 2)	In the 3b participants: Number of participants with a first occurrence of COVID-19 in participants with no evidence of prior infection starting 7 days after Second Dose of study vaccine
Percentage of participants reporting local reactions	For 7 days after Dose 1 and Dose 2	Solicited local AEs include injection site erythema, injection site pain, injection site induration/swelling, and injection site tenderness.
Percentage of participants reporting systemic events	For 7 days after Dose 1 and Dose 2	Solicited systemic AEs include arthralgia, chills, diarrhea, dizziness, fatigue, fever (categorized by measured body temperature), headache, myalgia, and nausea/vomiting.
Percentage of participants reporting serious adverse events, medically attended adverse events and adverse events leading to discontinuation	From Dose 1 through end of study	As elicited by investigational site staff
Neutralizing antibody (NAb) responses (for Phase 1/2/3a and Phase 3c)	Day 57 since the first administration of study vaccine	In Phase 1, 2, 3a and 3c-1 Participants: proportion of participants seroconverting for neutralizing antibodies at Day 57

Secondary Outcome Measures

Name	Time	Method
Geometric Mean Titers of SARS-CoV-2 neutralizing antibody titers	At baseline, and at Days 29, 57, 92 (Phase 1, 2, 3a only), 211 (Phase 3c-1 only) and 394 (Phase 1, 2, 3a only) after first administration of study vaccine	In Phase 1, 2, 3a and 3c-1 Participants: Geometric Mean Titers of SARS-CoV-2 neutralizing antibodies from before vaccination to each subsequent time point
Proportion of participants seroconverting for neutralizing antibodies	At baseline, and at Days 29, 57, 92 (Phase 1, 2, 3a only), 211 (Phase 3c-1 only) and 394 (Phase 1, 2, 3a only) after first administration of study vaccine	In Phase 1, 2, 3a and 3c-1 Participants: Proportion of participants seroconverting for neutralizing antibodies from before vaccination to each subsequent time point
Geometric Mean Titers of spike protein IgG binding antibodies	At baseline, and at Days 29, 57, 92 (Phase 1, 2, 3a only), 211 (Phase 3c-1 only) and 394 (Phase 1, 2, 3a only) after first administration of study vaccine	In Phase 1, 2, 3a and and 3c-1 Participants: Geometric Mean Titers of spike protein IgG binding antibodies from before vaccination to each subsequent time point
Proportion of participants seroconverting on PRNT50 or MNT	At Days 29 and 57 after first administration of study vaccine	In Phase 1, 2 and 3a Participants: proportion of participants seroconverting on PRNT50 from before vaccination to Day 29 and Day 57
Number of participants with a first occurrence of severe COVID-19	Day 37 to Day 92	In the pooled Phase 1, 2, 3a, 3b participants: Number of participants with a first occurrence of severe COVID-19 in participants with no evidence of prior infection starting 7 days after Second Dose of study vaccine
Number of participants with a first occurrence of COVID-19 irrespective of prior infection	Day 37 to Day 92	In the pooled Phase 1/2/3a/3b participants: Number of participants with a first occurrence of COVID-19 irrespective of prior infection starting 7 days after Second Dose of study vaccine.
Number of participants with a first occurrence of COVID-19	Day 1 to Day 92 (to evaluate vaccine efficacy at any time after first vaccination)]	In the 3b participants: Number of participants with a first occurrence of COVID-19 in participants with no evidence of prior infection starting 7 days after Second Dose of study vaccine
Geometric Mean Fold Ratio in SARS-CoV-2 neutralizing antibody titer	At baseline, and at Days 29, 57, 92 (Phase 1, 2, 3a only), 211 (Phase 3c-1 only) and 394 (Phase 1, 2, 3a only) after first administration of study vaccine	In Phase 1, 2, 3a and 3c-1 Participants: Geometric Mean Fold Ratio in SARS-CoV-2 neutralizing titer from before vaccination to each subsequent time point
Number of participants with a death due to COVID-19	Day 37 to Day 92	In the pooled Phase 1/2/3a/3b In Phase 3b participants: Number of participants with a death due to COVID-19 in participants with no evidence of prior infection starting 7 days after Second Dose of study vaccine.
Geometric Mean Fold Ratio of spike protein IgG binding antibodies	At baseline, and at Days 29, 57, 92 (Phase 1, 2, 3a only), 211 (Phase 3c-1 only) and 394 (Phase 1, 2, 3a only) after first administration of study vaccine	In Phase 1, 2, 3a and and 3c-1 Participants: Geometric Mean Fold Ratio of spike protein IgG binding antibodies from before vaccination to each subsequent time point
Proportion of participants seroconverting for spike protein IgG binding antibodies	At baseline, and at Days 29, 57, 92 (Phase 1, 2, 3a only), 211 (Phase 3c-1 only) and 394 (Phase 1, 2, 3a only) after first administration of study vaccine	In Phase 1, 2, 3a and 3c-1 Participants: proportion of participants seroconverting for spike protein IgG binding antibodies from before vaccination to each subsequent time point

Trial Locations

Locations (3)

Pasteur Institute; 🇻🇳 Ho Chi Minh City, Ho Chi Minh, Vietnam

Military Medical University; 🇻🇳 Ha Noi, Vietnam

Hanoi Medical University; 🇻🇳 Ha Noi, Vietnam