Open Label Extension Study to Assess the Safety and Long-Term Immunogenicity of ARCT-021

A Phase 2a, Open Label Extension Study to Assess the Safety and Long-Term Immunogenicity of ARCT-021

This is an open-label study enrolling healthy adults that participated in Study ARCT-021-01 (the Parent Study). Participants will receive either a single injection of ARCT-021 or no injection and be followed for up to 365 days.

Study Overview

• Status: Terminated
• Conditions: SARS-CoV-2
• Intervention / Treatment: Biological: ARCT-021

Detailed Description

This is a phase 2a, open-label study enrolling up to 106 healthy adults that participated in Study ARCT-021-01 (the Parent Study). Participants will enter this study approximately 3 months after their final study visit in the Parent Study. Participants that received placebo in the Parent Study or who are seronegative for SARS-CoV-2 neutralizing antibodies at screening will receive a single dose of ARCT-021 and will be followed for 365 days. Participants that received two injections of ARCT-021 in the Parent Study will not receive any further injections of ARCT-021 and will be followed for 281 days.

• Study Type: Interventional
• Enrollment (Actual): 65
• Phase: Phase 2

Contacts and Locations

Study Locations

• Singapore
  • Singapore, Singapore, 169608
    • SingHealth Investigational Medicine Unit (IMU), Singapore General Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 21 years to 80 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

Individuals who:

1. are able to give consent
2. must have completed Study ARCT-021-01

3. agree to comply with all study visits and procedures

   Only for subjects that will receive ARCT-021 in this study:

4. are healthy and medically stable
5. are not planning to donate blood or plasma until 28 days after the last dose of ARCT-021.
6. are willing to refrain from strenuous exercise/activity and alcohol for at least 72 hours prior to study visits and until 28 days after the last dose of ARCT-021.
7. are willing to adhere to contraception requirements if sexually active and/or are of child-bearing potential

Exclusion Criteria:

Individuals who:

1. are unable to comply with the study visits or procedures in Study ARCT-021-01

2. received placebo in the Parent Study and who are not willing to receive ARCT-021 in this study.

   Only for subjects that will receive ARCT-021 in this study:

3. have or will receive any of the SARS CoV-2 or another experimental coronavirus during this study.

4. have a diagnosis of new clinically significant abnormalities including but not limited to

   • Respiratory disease requiring daily medications or oxygen currently or any treatment of respiratory disease exacerbations
   • Significant heart conditions
   • Significant neurological conditions
   • Significant blood disorders
   • Newly diagnosed autoimmune disease
   • Major surgery
5. have abnormal screening laboratory results
6. have uncontrolled diabetes
7. use of any prescription or over-the-counter medications within 7 days prior to vaccination
8. have received immunoglobulins and/or any blood or blood products
9. have a bleeding disorder
10. have uncontrolled blood pressure
11. have been treated with another investigational drug, biological agent, or device since completion of the Parent Study

12. have received or plan to receive:

    • A licensed, live vaccine within 4 weeks before or after study vaccination, or
    • A licensed, inactivated vaccine within 2 weeks before or after study vaccination
13. have traveled outside of Singapore within 30 days before the vaccination or plans to travel outside of Singapore within 60 days after vaccination.
14. other restrictions may apply

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: ARCT-021; Participants will receive a single dose of ARCT-021 on Day 1	Biological: ARCT-021; ARCT-021 single dose
No Intervention: Long-term follow up from ARCT-021-01; Participants will not receive intervention but will be followed for safety.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of Participants With Solicited Local and Systemic Adverse Events	Solicited local adverse events were defined as pain, tenderness, erythema, or swelling at the injection site. Solicited systemic adverse events were defined as fever, fatigue, headache, chills, nausea, vomiting, diarrhoea, myalgia, and arthralgia. A summary of serious and all other non-serious adverse events regardless of causality is located in the Reported Adverse Events module.	Up to Day 7 (7 days after vaccine administration)
Number of Participants With Unsolicited Adverse Events	Unsolicited adverse events were defined as any spontaneously occurring adverse event (serious and non-serious). A summary of serious and all other non-serious adverse events regardless of causality is located in the Reported Adverse Events module.	Up to Day 29 (28 days after vaccine administration)
Number of Participants With Serious Adverse Events (SAEs), Unsolicited Adverse Events Associated With New Onset of Chronic Disease (NOCD) or Medically Attended Adverse Events (MAAEs)	SAEs were defined as any event that resulted in death, was life threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in a persistent or significant incapacity or substantial disruption of the ability to conduct normal life functions, a congenital anomaly or birth defect, or was an important medical event. A NOCD was defined as a MAAE that led to the new diagnosis of a chronic medical condition that was not present or suspected prior to enrollment. A MAAE was an adverse event that led to an unscheduled visit (including a telemedicine visit) to a healthcare practitioner. A summary of serious and all other non-serious adverse events regardless of causality is located in the Reported Adverse Events module.	Up to a maximum of approximately 12 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Geometric Mean Titer (GMT) of Serum Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Neutralizing Antibodies		Cohorts 1a and 1b: Days 1, 29, 57, Cohort 2: Day 29
Geometric Mean Fold Rise (GMFR) in SARS-CoV-2 Neutralizing Antibody Titers		Cohort 1a: Days 29, 57, Cohort 1b: Days 1, 29, 57, and Cohort 2: Day 29
Number of ARCT-021-naïve Participants (Cohort 1a) With Seroconversion (Neutralizing Antibodies)	Seroconversion was defined as a 4-fold increase in antibody titer/concentration from baseline. Data is presented for the number of participants seroconverting for neutralizing antibodies and immunoglobulin G (IgG) antibodies against the full-length SARS-CoV-2 recombinant spike protein antigen and spike protein receptor binding domain of the SARS-CoV-2 spike glycoprotein (RBD). ARCT-021-naïve participants were those participants whose first ARCT-021 vaccine administration occurred in this study (Cohort 1a). As pre-specified, data is presented for participants in Cohort 1a only.	Days 29, and 57
Geometric Mean Concentration (GMC) of Serum SARS-CoV-2 Binding Antibodies	GMC data are reported for the S (spike binding antibodies) analyte.	Cohorts 1a and 1b: Days 1, 29, 57, Cohort 2: Day 29
GMFR in SARS-CoV-2 Binding Antibody Titers	GMFR data are reported for the S (spike binding antibodies) analyte.	Cohort 1a: Days 29, 57, Cohort 1b: Days 1, 29, 57, and Cohort 2: Day 29
Number of ARCT-021-naïve Participants (Cohort 1a) With Seroconversion (Binding Antibodies)	Seroconversion was defined as a 4-fold increase in antibody titer/concentration from baseline. Data is presented for the number of participants seroconverting for binding antibodies and immunoglobulin G (IgG) antibodies against the full-length SARS-CoV-2 recombinant spike protein antigen and spike protein receptor binding domain of the SARS-CoV-2 spike glycoprotein (RBD). ARCT-021-naïve participants were those participants whose first ARCT-021 vaccine administration occurred in this study (Cohort 1a). As pre-specified, data is presented for participants in Cohort 1a only.	Days 29, and 57

Collaborators and Investigators

• Sponsor: Arcturus Therapeutics, Inc.

Study record dates

Study Major Dates

• Study Start (Actual): January 4, 2021
• Primary Completion (Actual): December 28, 2021
• Study Completion (Actual): December 28, 2021

Study Registration Dates

• First Submitted: January 24, 2021
• First Submitted That Met QC Criteria: January 24, 2021
• First Posted (Actual): January 28, 2021

Study Record Updates

• Last Update Posted (Actual): March 25, 2025
• Last Update Submitted That Met QC Criteria: December 6, 2024
• Last Verified: December 1, 2024

More Information

Terms related to this study

• Other Study ID Numbers: ARCT-021-02

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.: Yes