Study of GRT-R910 COVID-19 Boost Vaccine in Healthy Volunteers

A Phase 1 Trial to Evaluate the Safety, Immunogenicity, and Reactogenicity of a Self-Amplifying mRNA Prophylactic Vaccine Boost Against SARS-CoV-2 in Previously Vaccinated Healthy Adults 18 Years and Older

The primary objective was to assess the safety and tolerability of 2 different doses (10 or 30 µg) of GRT-R910 when administered as a boost in healthy adults previously vaccinated with the AstraZeneca, Janssen/Johnson and Johnson, Moderna, or Pfizer/BioNTech Coronavirus disease 2019 (COVID-19) vaccines.

Study Overview

• Status: Completed
• Conditions: COVID-19
• Intervention / Treatment: Biological: GRT-R910

Detailed Description

This trial studied a self-amplifying messenger ribonucleic acid (samRNA) based vaccine (GRT-R910) in previously vaccinated adults (≥18 years). GRT-R910 uses a codon optimized, prefusion stabilized Spike (S) cassette with additional T cell epitopes (TCEs) covering multiple epitopes from non-spike proteins to safely drive strong, broad, and durable B and T cell immune responses to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2).

• Study Type: Interventional
• Enrollment (Actual): 45
• Phase: Phase 1

Contacts and Locations

Study Locations

• United Kingdom
  • Birmingham, United Kingdom
    • University Hospitals Birmingham NHS
  • Leicester, United Kingdom
    • University Hospital of Leicester NHS Trust
  • Manchester, United Kingdom
    • Manchester University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• For Cohorts 1 and 2, have received AstraZeneca's AZD1222 COVID-19 prime and boost vaccine (Covishield®, Vaxzevria®), with the last dose received at least 2 months or more prior to Day 1.
• For Cohort 3, have received a primary series of an adenoviral (AstraZeneca AZD1222 [Covishield®, Vaxzevria®] or Janssen [Janssen COVID-19 Vaccine]) COVID-19 vaccine (under emergency supply procedures or upon full approval and may have received booster doses of an authorized vaccine), with the last dose received at least 2 months or more prior to Day 1.
• For Cohorts 4 and 6, have received a primary series of an mRNA (Pfizer/BioNTech [Comirnaty®] or Moderna [Spikevax®]) COVID-19 vaccine (under emergency supply procedures or upon full approval and may have received booster doses of an authorized vaccine), with the last dose received at least 2 months or more prior to Day 1.
• Agree to refrain from blood donation during the course of the study.
• Women of childbearing potential (WOCBP)* must agree to avoid pregnancy and be willing to use a highly effective method of contraception** consistently for 30 days prior to the first study vaccine and for at least 60 days after the last study vaccine
• Male subjects of childbearing potential must agree to the use of condoms to ensure effective contraception with a female partner from the time of study vaccination until 3 months after vaccination. Male subjects agree to refrain from sperm donation from the time of first vaccination until 3 months after the last vaccination. Male subjects of childbearing potential are biological males who are post-pubertal and considered fertile until permanently sterile by bilateral orchiectomy or vasectomy.
• Plan to remain living in the area for the duration of the study.

Exclusion Criteria:

• History of prior confirmed COVID-19 (cohorts 1 and 2).
• History of prior confirmed (polymerase chain reaction [PCR] or antigen test positive) COVID-19 infection as confirmed by a diagnostic laboratory less than 16 weeks (112 days) prior to enrollment (Cohorts 3, 4, and 6).
• Positive for SARS-CoV-2 (N-specific) antibody testing and had a history of upper respiratory illness consistent with COVID-19 within the 112 days prior to enrollment (Cohorts 3, 4, and 6).
• Prior receipt of a SARS-CoV-2 vaccine other than AstraZeneca's AZD1222 (Covishield®, Vaxzevria®), JNJ-78436735, Pfizer/BioNTech (Comirnaty®), Moderna (Spikevax®), other approved or investigational adenovirus vectored vaccines, approved or investigational vaccines with a lipid nanoparticle (LNP) component, or any other approved or investigational vaccine likely to impact the interpretation of the trial data.
• On current treatment or prevention agents with activity against SARS-CoV-2.
• Participation in another research study involving receipt of an investigational product in the 60 days preceding enrollment or planned use during the study period.
• Receipt or planned receipt of any live, attenuated vaccine within 28 days before or after study vaccination.
• Receipt or planned receipt of any subunit or killed vaccine within 14 days before or after vaccination.
• Administration of immunoglobulins and/or any blood products within the 3 months preceding the planned administration of first study vaccination or at any time during the study.
• Breastfeeding, pregnant, or planning to become pregnant during the course of the study.
• Any confirmed or suspected immunosuppressive or immunodeficient state, including HIV infection with CD4+ T-cells < 400/mm3, asplenia, recurrent, severe infections and chronic (more than 14 continuous days) immunosuppressant medication within the past 6 months (inhaled, ophthalmic, and topical steroids are allowed).
• History of allergic disease or reactions likely to be exacerbated by any component of the vaccine, including urticaria, respiratory difficulty or abdominal pain (or any immediate allergic reaction of any severity to polysorbate due to potential cross-reactive hypersensitivity with the PEG component of the vaccine).
• Any history of hereditary angioedema, acquired angioedema, or idiopathic angioedema.
• Any history of anaphylaxis, including but not limited to reaction to vaccination.
• History of cancer (except basal cell carcinoma of the skin and cervical carcinoma in situ).
• History of serious ongoing, unstable psychiatric condition that in the opinion of the investigator would interfere with study participation.
• Bleeding disorder or prior history of significant bleeding or bruising following IM injections or venipuncture.
• Suspected or known current alcohol abuse that in the opinion of the investigator would impede compliance with the protocol and schedules of assessments.
• Suspected or known current alcohol abuse that in the opinion of the investigator would impede compliance with the protocol and schedules of assessments. Suspected or known drug abuse in the 5 years preceding enrollment.
• Any other condition that in the opinion of the investigator would pose a health risk to the participant if enrolled or could interfere with evaluation of the trial vaccine or interpretation of study results.

Study Plan

How is the study designed?

Design Details

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

Number of Arms

5

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Cohort 1: GRT-R910 10 µg, age ≥60 years (Receipt of AstraZeneca vaccine); Healthy participants of age ≥60 years received prime dose (on Day 1) of GRT-R910 10 microgram (µg) intramuscularly at least 2 months after receiving a first-generation COVID-19 (AstraZeneca) vaccine primary series. A subset of participants elected to receive a booster vaccination of GRT-R910 10 µg which was administered 113 days after the prime vaccination. Participants not receiving booster dose were followed for 12 months, and participants receiving booster dose were followed for 16 months.	Biological: GRT-R910; Injection administered intramuscularly
Experimental: Cohort 2: GRT-R910 30 µg, age ≥60 years (Receipt of AstraZeneca vaccine); Healthy participants of age ≥60 years received prime dose (on Day 1) of GRT-R910 30 µg intramuscularly at least 2 months after receiving a first-generation COVID-19 (AstraZeneca) vaccine primary series. A subset of participants elected to receive a booster vaccination of GRT-R910 10 µg, which was administered 113 days after the prime vaccination. Participants not receiving booster dose were followed for 12 months, and participants receiving booster dose were followed for 16 months.	Biological: GRT-R910; Injection administered intramuscularly
Experimental: Cohort 3: GRT-R910 10 µg, ≥60 years, (Receipt of AstraZeneca or Janssen COVID-19 vaccine); Healthy participants of age ≥60 years received two doses (Day 1 and Day 29) of GRT-R910 10 µg (homologous prime-boost), at least 2 months after receiving an adenoviral COVID-19 (AstraZeneca, Janssen) primary series vaccine. Participants were followed for 13 months.	Biological: GRT-R910; Injection administered intramuscularly
Experimental: Cohort 4: GRT-R910 10 µg, ≥60 years, (Receipt of Pfizer/BioNTech, Moderna COVID-19 vaccine); Healthy participants of age ≥60 years received two doses (Day 1 and Day 29) of GRT-R910 10 µg (homologous prime-boost), at least 2 months after receiving a messenger ribonucleic acid (mRNA)-based COVID-19 (Pfizer/BioNTech, Moderna) primary series vaccine. Participants were followed for 13 months.	Biological: GRT-R910; Injection administered intramuscularly
Experimental: Cohort 6: GRT-R910 10 µg, ≥18 to ≤59 years, (Receipt of Pfizer/BioNTech, Moderna COVID-19 vaccine); Healthy participants of age ≥18 to ≤59 years received two doses (Day 1 and Day 29) of GRT-R910 10 µg (homologous prime-boost), at least 2 months after receiving mRNA-based COVID-19 (Pfizer/BioNTech, Moderna) primary series vaccine. Participants were followed for 13 months.	Biological: GRT-R910; Injection administered intramuscularly

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of Participants With at Least One Solicited Local Adverse Event (AE) Within 8 Days After the Injection of Prime Dose	An AE was defined as any untoward medical occurrence associated with the use of an intervention in humans, whether or not considered intervention-related in a participant or clinical investigation participant who administered a pharmaceutical product regardless of its causal relationship to the study treatment. Solicited local AEs included injection site pain, injection site tenderness, injection site erythema, injection site edema/induration. Solicited AEs (reactogenicity) were collected using a memory aid.	Within 8 Days After the Injection of Prime Dose on Day 1
Number of Participants With at Least One Solicited Local AE Within 8 Days After the Injection of Booster Dose	An AE was defined as any untoward medical occurrence associated with the use of an intervention in humans, whether or not considered intervention-related in a participant or clinical investigation participant who administered a pharmaceutical product regardless of its causal relationship to the study treatment. Solicited local AEs included injection site pain, injection site tenderness, injection site erythema, injection site edema/induration. Solicited AEs (reactogenicity) were collected using a memory aid.	Within 8 Days After the Injection of Booster Dose on Day 113 (Cohorts 1, 2); Within 8 Days After the Injection of Booster Dose on Day 29 (Cohorts 3, 4, 6)
Number of Participants With at Least One Solicited Systemic AE Within 8 Days After the Injection of Prime Dose	An AE was defined as any untoward medical occurrence associated with the use of an intervention in humans, whether or not considered intervention-related in a participant or clinical investigation participant who administered a pharmaceutical product regardless of its causal relationship to the study treatment. Solicited systemic AEs included headache, fatigue, malaise, myalgia, arthralgia, nausea, fever, and chills. Solicited AEs (reactogenicity) were collected using a memory aid.	Within 8 Days After the Injection of Prime Dose on Day 1
Number of Participants With at Least One Solicited Systemic AE Within 8 Days After the Injection of Booster Dose	An AE was defined as any untoward medical occurrence associated with the use of an intervention in humans, whether or not considered intervention-related in a participant or clinical investigation participant who administered a pharmaceutical product regardless of its causal relationship to the study treatment. Solicited systemic AEs included headache, fatigue, malaise, myalgia, arthralgia, nausea, fever, and chills. Solicited AEs (reactogenicity) were collected using a memory aid.	Within 8 Days After the Injection of Booster Dose on Day 113 (Cohorts 1, 2); Within 8 Days After the Injection of Booster Dose on Day 29 (Cohorts 3, 4, 6)
Number of Participants With at Least One Unsolicited Treatment-emergent AEs (TEAEs) Within 28 Days After the Injection of Prime Dose	An AE was defined as any untoward medical occurrence associated with the use of an intervention in humans, whether or not considered intervention-related in a participant or clinical investigation participant who administered a pharmaceutical product regardless of its causal relationship to the study treatment. A TEAE was defined as any event not observed before the first vaccination or any event observed before the first vaccination that worsens in intensity or frequency after exposure.	Within 28 Days After the Injection of Prime Dose on Day 1
Number of Participants With at Least One Unsolicited TEAEs Within 28 Days After the Injection of Booster Dose	An AE was defined as any untoward medical occurrence associated with the use of an intervention in humans, whether or not considered intervention-related in a participant or clinical investigation participant who administered a pharmaceutical product regardless of its causal relationship to the study treatment. A TEAE was defined as any event not observed before the first vaccination or any event observed before the first vaccination that worsens in intensity or frequency after exposure.	Within 28 Days After the Injection of Booster Dose on Day 113 (Cohorts 1, 2); Within 8 Days After the Injection of Booster Dose on Day 29 (Cohorts 3, 4, 6)
Change From Baseline in Basophils, Eosinophils, Lymphocytes, Monocytes, Neutrophils, Platelets, Leukocytes at Day 8 in Participants Without Booster Dose (Cohorts 1 and 2)		Baseline, Day 8
Change From Baseline in Basophils, Eosinophils, Lymphocytes, Monocytes, Neutrophils, Platelets, Leukocytes at Day 8 in Participants With Booster Dose (Cohorts 1 and 2)		Baseline, Day 8
Change From Baseline in Basophils, Eosinophils, Lymphocytes, Monocytes, Neutrophils, Platelets, Leukocytes at Day 120 in Participants With Booster Dose (Cohorts 1 and 2)		Baseline, Day 120
Change From Baseline in Basophils, Eosinophils, Lymphocytes, Monocytes, Neutrophils, Platelets, Leukocytes at Day 8 in Cohorts 3, 4, and 6		Baseline, Day 8
Change From Baseline in Basophils, Eosinophils, Lymphocytes, Monocytes, Neutrophils, Platelets, Leukocytes at Day 37 in Cohorts 3, 4, and 6		Baseline, Day 37
Change From Baseline in Hemoglobin at Day 8 in Participants Without Booster Dose (Cohorts 1 and 2)		Baseline, Day 8
Change From Baseline in Hemoglobin at Day 8 in Participants With Booster Dose (Cohorts 1 and 2)		Baseline, Day 8
Change From Baseline in Hemoglobin at Day 120 in Participants With Booster Dose (Cohorts 1 and 2)		Baseline, Day 120
Change From Baseline in Hemoglobin at Day 8 in Cohorts 3, 4, and 6		Baseline, Day 8
Change From Baseline in Hemoglobin at Day 37 in Cohorts 3, 4, and 6		Baseline, Day 37
Change From Baseline in Alkaline Phosphatase, Alanine Aminotransferase, and Aspartate Aminotransferase at Day 8 in Participants Without Booster Dose (Cohorts 1 and 2)		Baseline, Day 8
Change From Baseline in Alkaline Phosphatase, Alanine Aminotransferase, and Aspartate Aminotransferase at Day 8 in Participants With Booster Dose (Cohorts 1 and 2)		Baseline, Day 8
Change From Baseline in Alkaline Phosphatase, Alanine Aminotransferase, and Aspartate Aminotransferase at Day 120 in Participants With Booster Dose (Cohorts 1 and 2)		Baseline, Day 120
Change From Baseline in Alkaline Phosphatase, Alanine Aminotransferase, and Aspartate Aminotransferase at Day 8 in Cohorts 3, 4, and 6		Baseline, Day 8
Change From Baseline in Alkaline Phosphatase, Alanine Aminotransferase, and Aspartate Aminotransferase at Day 37 in Cohorts 3, 4, and 6		Baseline, Day 37
Change From Baseline in Bilirubin and Creatinine at Day 8 in Participants Without Booster Dose (Cohorts 1 and 2)		Baseline, Day 8
Change From Baseline in Bilirubin and Creatinine at Day 8 in Participants With Booster Dose (Cohorts 1 and 2)		Baseline, Day 8
Change From Baseline in Bilirubin and Creatinine at Day 120 in Participants With Booster Dose (Cohorts 1 and 2)		Baseline, Day 120
Change From Baseline in Bilirubin and Creatinine at Day 8 in Cohorts 3, 4, and 6		Baseline, Day 8
Change From Baseline in Bilirubin and Creatinine at Day 37 in Cohorts 3, 4, and 6		Baseline, Day 37
Change From Baseline in Creatine Kinase at Day 8 in Participants Without Booster Dose (Cohorts 1 and 2)		Baseline, Day 8
Change From Baseline in Creatine Kinase at Day 8 in Participants With Booster Dose (Cohorts 1 and 2)		Baseline, Day 8
Change From Baseline in Creatine Kinase at Day 120 in Participants With Booster Dose (Cohorts 1 and 2)		Baseline, Day 120
Change From Baseline in Creatine Kinase at Day 8 in Cohorts 3, 4, and 6		Baseline, Day 8
Change From Baseline in Creatine Kinase at Day 37 in Cohorts 3, 4, and 6		Baseline, Day 37
Number of Participants With Treatment-emergent Serious AEs (SAEs), AE of Special Interest (AESIs) Including Potentially Immune-mediated Medical Conditions (PIMMCs), Medically Attended AEs (MAAEs), and New Onset Chronic Medical Conditions (NOCMCs)	An AE or adverse experience was defined as any untoward medical occurrence in a participant or clinical investigation participant who was administered a pharmaceutical product, with or without a causal relationship with the vaccine. A TEAE was defined as any event not observed before the first vaccination or any event observed before the first vaccination that worsens in intensity or frequency after exposure. A treatment-emergent SAE was defined as any AE that resulted in death, is life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in disability/permanent damage, was a congenital anomaly/birth defect, or was an important medical event. Adverse events of special interest were serologically or virologically confirmed SARS-CoV-2 infection or severe COVID-19, NOCMCs, MAAE (hospitalization, an emergency room visit or an otherwise unscheduled visit to or from medical personnel for any reason), and PIMMCs.	Day 1 Up to 16 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change From Baseline in Immunoglobulin (Ig)G Level (Spike Wild Type [WT] Variant)	Sera were analyzed for Spike (WT variant)-specific IgG levels pre and post administration of GRT-R910 via enzyme-linked immunosorbent assay (ELISA) and reported as ELISA laboratory units (ELU)/mL (amount of antibodies in the sample according to the unit assigned by the standard).	Baseline, Days 15, 29, 57, 58, 86, 113, 142, 180, 209, 293, 365, 394, 478
Change From Baseline in Neutralizing Antibody (nAb) Levels	Neutralizing antibody titers against live virus were assessed via microneutralization assay. Neutralizing antibody levels were measured for the following variants: WT, Alpha, Beta, Delta, Gamma.	For WT: Baseline, Days 15, 29, 57, 58, 86, 113, 142, 180, 209 293, 365, 394, 478; For Alpha, Beta, Delta, Gamma:Baseline, Days 15, 29, 57, 58, 86, 113, 142, 180, 209 293, 365, 394
Number of Participants With Immunogenicity Response by Spike IgG and nAb Variants	Immunogenicity response defined as >= 2-fold change in the levels from baseline. Response rate was assessed by Spike IgG wild type and nAb Variants [wild type, alpha, beta, gamma, delta]. Number of participants with immunogenicity response at any post-baseline timepoint are provided.	Baseline to 478 days
Change From Baseline in T Cell Response by Spike Pools (ex Vivo ELISpot)	Peripheral blood mononuclear cells (PBMCs) were isolated from whole blood. T cell responses to SARS-CoV-2 D614G were assessed via ex vivo IFNγ ELISpot assay (methods). Cells were stimulated with overlapping peptide (OLP) pools containing peptides that were 15 amino acids in length (15mers) and spanning both S subunits (Spike pool 1-2, 3-4 [S1], 5-6, and 7-8 [S2]).	Baseline, Days 8, 29, 58, 113, 142, 180, 209, 293, 365, 478
Change From Baseline in T Cell Response by T Cell Epitope (TCE) Pools (ex Vivo ELISpot)	PBMCs were isolated from whole blood. T cell responses to conserved SARS-CoV-2 viral epitopes were assessed via ex vivo IFNγ ELISpot assay (methods). Responses to Nucleocapsid (Nuc) and open reading frame 3a (ORF3a)/Membrane TCE regions were assessed using OLP pools.	Baseline, Days 8, 29, 58, 113, 142, 180, 209, 293, 365, 478
Change From Baseline in Immunogenicity Response by TCE Pools (in Vitro Stimulation)	PBMCs were isolated from whole blood. T cell responses to conserved SARS-CoV-2 viral epitopes were assessed via IFNγ ELISpot assay following in vitro stimulation. Responses to Nuc, ORF3a, and membrane TCE regions were assessed using OLP pools.	Baseline, Days 8, 29, 58, 113, 142, 180, 209, 293
Number of Participants With Immunogenicity Response by Spike Pools and TCE Pools (ex Vivo ELISpot)	T cell responses to SARS-CoV-2 D614G and conserved non-Spike epitopes were assessed via ex vivo IFNγ ELISpot assay (methods) using OLP pools containing peptides that were 15 amino acids in length and spanning both S subunits (Spike pool 1-2, 3-4 [S1], 5-6, and 7-8 [S2]) and TCE regions Nuc and ORF3a/Membrane. Immunogenicity response was defined as >= 2-fold change in levels from baseline. Response rate to both Spike pools (Spike pool 1-2, 3-4, 5-6, and 7-8) and TCE pools (Nuc OLP and ORF3a/Membrane OLP) was assessed.	Baseline to 478 days

Collaborators and Investigators

• Sponsor: Gritstone bio, Inc.
• Investigators: Study Director: Elizabeth Martin, DO, Gritstone bio, Inc.

Study record dates

Study Major Dates

• Study Start (Actual): September 16, 2021
• Primary Completion (Actual): May 26, 2023
• Study Completion (Actual): May 26, 2023

Study Registration Dates

• First Submitted: December 3, 2021
• First Submitted That Met QC Criteria: December 3, 2021
• First Posted (Actual): December 8, 2021

Study Record Updates

• Last Update Posted (Estimated): December 11, 2024
• Last Update Submitted That Met QC Criteria: December 3, 2024
• Last Verified: December 1, 2024

More Information

Terms related to this study

• Keywords: SARS-CoV-2 vaccine; Coronavirus Disease (COVID-19)
• Additional Relevant MeSH Terms: Respiratory Tract Infections; Infections; RNA Virus Infections; Virus Diseases; Respiratory Tract Diseases; Lung Diseases; Pneumonia, Viral; Pneumonia; Coronavirus Infections; Coronaviridae Infections; Nidovirales Infections; COVID-19; Physiological Effects of Drugs; Immunologic Factors; Vaccines
• Other Study ID Numbers: GO-009

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: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No