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

Phase 2

Terminated

• Conditions: SARS-CoV-2
• Interventions: Biological: ARCT-021

• Registration Number: NCT04728347
• Lead Sponsor: Arcturus Therapeutics, Inc.

Brief Summary

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.

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 Timeline

• Study Start: 2021-01-04
• Study First Submitted: 2021-01-24
• Study First Submitted QC: 2021-01-24
• Study First Posted: 2021-01-28
• Primary Completion: 2021-12-28
• Study Completion: 2021-12-28
• Results First Submitted: 2024-10-18
• Status Verified: 2024-12
• Results First Submitted QC: 2024-12-06
• Last Update Submitted: 2024-12-06
• Results First Posted: 2024-12-30
• Last Update Posted: 2024-12-30

Recruitment & Eligibility

• Status: TERMINATED
• Sex: All
• Target Recruitment: 65

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

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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

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Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
ARCT-021	ARCT-021	Participants will receive a single dose of ARCT-021 on Day 1

Primary Outcome Measures

Name	Time	Method
Number of Participants With Solicited Local and Systemic Adverse Events	Up to Day 7 (7 days after vaccine administration)	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.
Number of Participants With Unsolicited Adverse Events	Up to Day 29 (28 days after vaccine administration)	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.
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)	Up to a maximum of approximately 12 months	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.

Secondary Outcome Measures

Name	Time	Method
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)	Days 29, and 57	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.
Geometric Mean Concentration (GMC) of Serum SARS-CoV-2 Binding Antibodies	Cohorts 1a and 1b: Days 1, 29, 57, Cohort 2: Day 29	GMC data are reported for the S (spike binding antibodies) analyte.
GMFR in SARS-CoV-2 Binding Antibody Titers	Cohort 1a: Days 29, 57, Cohort 1b: Days 1, 29, 57, and Cohort 2: Day 29	GMFR data are reported for the S (spike binding antibodies) analyte.
Number of ARCT-021-naïve Participants (Cohort 1a) With Seroconversion (Binding Antibodies)	Days 29, and 57	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.

Trial Locations

Locations (1)

SingHealth Investigational Medicine Unit (IMU), Singapore General Hospital; 🇸🇬 Singapore, Singapore