NCT04852978

Brief Summary

The primary objectives of the study are:

  • To evaluate the extent of effect, if any, of REGN10933+REGN10987 administration on vaccine-induced neutralizing antibody responses to SARS-CoV-2 by Moderna mRNA-1273
  • To evaluate the time interval required between REGN10933+REGN10987 administration and Moderna mRNA-1273 vaccination, to ensure no meaningful impact on vaccine-induced neutralizing antibody responses to SARS-CoV-2 The secondary objectives of the study are:
  • To quantify the alteration of antigen specificity of vaccine-induced SARS-CoV-2 antibody responses when administered with different dose regimens of REGN10933+REGN10987
  • To evaluate the safety and tolerability of REGN10933+REGN10987 and Moderna mRNA-1273 vaccine when administered in close succession
  • To assess the concentrations of REGN10933 and REGN10987 in serum over time in participants who receive REGN10933+REGN10987 and Moderna mRNA-1273 vaccine
  • To evaluate the immunogenicity of REGN10933 and REGN10987 over time

Trial Health

87
On Track

Trial Health Score

Automated assessment based on enrollment pace, timeline, and geographic reach

Enrollment
295

participants targeted

Target at P75+ for phase_2 healthy

Timeline
Completed

Started Apr 2021

Geographic Reach
1 country

6 active sites

Status
completed

Health score is calculated from publicly available data and should be used for screening purposes only.

Trial Relationships

Click on a node to explore related trials.

Study Timeline

Key milestones and dates

First Submitted

Initial submission to the registry

April 19, 2021

Completed
2 days until next milestone

First Posted

Study publicly available on registry

April 21, 2021

Completed
8 days until next milestone

Study Start

First participant enrolled

April 29, 2021

Completed
1.6 years until next milestone

Primary Completion

Last participant's last visit for primary outcome

November 21, 2022

Completed
Same day until next milestone

Study Completion

Last participant's last visit for all outcomes

November 21, 2022

Completed
1.7 years until next milestone

Results Posted

Study results publicly available

August 20, 2024

Completed
Last Updated

October 20, 2025

Status Verified

October 1, 2025

Enrollment Period

1.6 years

First QC Date

April 19, 2021

Results QC Date

November 20, 2023

Last Update Submit

October 9, 2025

Conditions

HealthyChronic Stable Illness

Outcome Measures

Primary Outcomes (2)

  • 50% Inhibitory Dilution (ID50) Titers of Vaccine-induced Neutralizing Antibodies to the SARS-CoV-2 S Protein in Individuals Who Received High Dose REGN10933+REGN10987 (1200 mg)

    High dose - (1200 mg arms)

    56 days after first dose of vaccine

  • 50% Inhibitory Dilution (ID50) Titers of Vaccine-induced Neutralizing Antibodies to the SARS-CoV-2 S Protein in Individual Who Received Submaximal Dose Levels of REGN10933+REGN10987 (Less Than 1200 mg)

    Submaximal dose - (150 mg, 300 mg, 600 mg, 48 mg, and 12 mg)

    56 days after first dose of vaccine

Secondary Outcomes (31)

  • Absolute Values in Concentrations of Vaccine-induced Antibodies to SARS-CoV-2 Antigens Over Time (S1-RBD IgA)

    Up to 365 Days from 1st dose of Vaccination

  • Median Fold Change of Concentrations of Vaccine-induced Antibodies to SARS-CoV-2 Antigens Over Time (S1-RBD IgA)

    Up to 365 Days from 1st dose of Vaccination

  • Relative Difference Expressed as a Percent in Vaccine-induced Antibodies to SARS-CoV-2 Antigens Over Time (S1-RBD IgA)

    Up to 365 Days from 1st dose of Vaccination

  • Absolute Values in Concentrations of Vaccine-induced Antibodies to SARS-CoV-2 Antigens Over Time (S-IgA)

    Up to 365 Days from 1st dose of Vaccination

  • Fold Change of Concentrations of Vaccine-induced Antibodies to SARS-CoV-2 Antigens Over Time (S-IgA)

    Up to 365 Days from 1st dose of vaccination

  • +26 more secondary outcomes

Study Arms (12)

Wave 1 Dose 1

EXPERIMENTAL
Drug: casirivimab+imdevimabBiological: Moderna mRNA-1273 vaccine

Wave 1 Dose 2

EXPERIMENTAL
Drug: casirivimab+imdevimabBiological: Moderna mRNA-1273 vaccine

Wave 1 Dose 3

EXPERIMENTAL
Drug: casirivimab+imdevimabBiological: Moderna mRNA-1273 vaccine

Wave 1 Vaccine only

EXPERIMENTAL
Biological: Moderna mRNA-1273 vaccine

Wave 2 Dose 1

EXPERIMENTAL
Drug: casirivimab+imdevimabBiological: Moderna mRNA-1273 vaccine

Wave 2 Dose 2

EXPERIMENTAL
Drug: casirivimab+imdevimabBiological: Moderna mRNA-1273 vaccine

Wave 2 Vaccine only

EXPERIMENTAL
Biological: Moderna mRNA-1273 vaccine

Wave 3 Dose 1

EXPERIMENTAL
Drug: casirivimab+imdevimabBiological: Moderna mRNA-1273 vaccine

Wave 3 Dose 2

EXPERIMENTAL
Drug: casirivimab+imdevimabBiological: Moderna mRNA-1273 vaccine

Wave 3 Vaccine only

EXPERIMENTAL
Biological: Moderna mRNA-1273 vaccine

Wave 4 Dose 1

EXPERIMENTAL
Drug: casirivimab+imdevimabBiological: Moderna mRNA-1273 vaccine

Wave 4 Vaccine only

EXPERIMENTAL
Biological: Moderna mRNA-1273 vaccine

Interventions

casirivimab+imdevimabDRUG

Wave 1 Intravenous (IV) administration Wave 2 Subcutaneous administration

Also known as: REGN10933, REGN10987, REGN-COV2, REGEN-COVâ„¢, Ronapreveâ„¢
Wave 1 Dose 1Wave 1 Dose 2Wave 1 Dose 3Wave 2 Dose 1Wave 2 Dose 2Wave 3 Dose 1Wave 3 Dose 2Wave 4 Dose 1
Moderna mRNA-1273 vaccineBIOLOGICAL

Single intramuscular (IM) injection

Wave 1 Dose 1Wave 1 Dose 2Wave 1 Dose 3Wave 1 Vaccine onlyWave 2 Dose 1Wave 2 Dose 2Wave 2 Vaccine onlyWave 3 Dose 1Wave 3 Dose 2Wave 3 Vaccine onlyWave 4 Dose 1Wave 4 Vaccine only

Eligibility Criteria

Age18 Years - 90 Years
Sexall
Healthy VolunteersYes
Age GroupsAdult (18-64), Older Adult (65+)

You may qualify if:

  • Healthy or has chronic medical condition(s) that are stable and well-controlled in the opinion of the investigator and that are not likely to require significant medical intervention through the end of study
  • Willing and able to comply with study visits and study-related procedures, including compliance with site precautionary requirements related to SARS-CoV-2 infection and transmission

You may not qualify if:

  • Positive RT-PCR test result for SARS-CoV-2 infection at screening or baseline
  • Positive serology test result for anti-SARS-CoV-2 antibodies at screening or baseline
  • COVID-19 diagnosis, positive SARS-CoV-2 infection, or positive SARS-CoV-2 serology at any time prior to screening
  • Previously received an investigational, authorized, or approved coronavirus vaccine (eg, SARS-CoV-2 vaccine, MERS-CoV vaccine)
  • Currently enrolled in, or has plans to enroll in, any interventional study to prevent or treat COVID-19
  • Received investigational or approved passive antibodies for SARS-CoV-2 infection prophylaxis ad defined in the protocol
  • Received intravenous immunoglobulin (IVIG) or blood products in the last 3 months
  • Any physical examination findings and/or history of any illness that, in the opinion of the study investigator, might confound the results of the study or pose an additional risk to the subject by study participation
  • History of clinically significant cardiovascular, respiratory, hepatic, renal, gastrointestinal, endocrine, hematological, psychiatric or neurological disease, as assessed by the investigator, that may confound the results of the study or pose an additional risk to the subject by study participation
  • Medically attended acute illness or hospitalization (ie, \>24 hours) for any reason within 30 days prior to screening
  • Clinical history of myocarditis and/or pericarditis

Contact the study team to confirm eligibility.

Sponsors & Collaborators

Study Sites (6)

Regeneron Research Site

Little Rock, Arkansas, 72211, United States

Location

Regeneron Research Site

Rogers, Arkansas, 72758, United States

Location

Regeneron Research Site

Hialeah, Florida, 33012, United States

Location

Regeneron Research Site

Miami, Florida, 33186, United States

Location

Regeneron Research Site

Orlando, Florida, 32789, United States

Location

Regeneron Research Site

Dayton, Ohio, 45417, United States

Location

Related Publications (1)

  • Isa F, Gonzalez Ortiz AM, Meyer J, Hamilton JD, Olenchock BA, Brackin T, Ganguly S, Forleo-Neto E, Faria L, Heirman I, Marovich M, Hutter J, Polakowski L, Irvin SC, Thakur M, Hooper AT, Baum A, Petro CD, Fakih FA, McElrath MJ, De Rosa SC, Cohen KW, Williams LD, Hellman CA, Odeh AJ, Patel AH, Tomaras GD, Geba GP, Kyratsous CA, Musser B, Yancopoulos GD, Herman GA; Trial Working Group. Effect of timing of casirivimab and imdevimab administration relative to mRNA-1273 COVID-19 vaccination on vaccine-induced SARS-CoV-2 neutralising antibody responses: a prospective, open-label, phase 2, randomised controlled trial. Lancet Infect Dis. 2025 Jan;25(1):52-67. doi: 10.1016/S1473-3099(24)00421-3. Epub 2024 Sep 2.

    PMID: 39236733DERIVED

MeSH Terms

Interventions

casirivimab and imdevimab drug combinationcasirivimabimdevimab2019-nCoV Vaccine mRNA-1273

Intervention Hierarchy (Ancestors)

mRNA VaccinesNucleic Acid-Based VaccinesVaccines, SyntheticRecombinant ProteinsProteinsAmino Acids, Peptides, and ProteinsVaccinesBiological ProductsComplex MixturesCOVID-19 VaccinesViral VaccinesAntigensBiological Factors

Results Point of Contact

Title
Clinical Trials Administrator
Organization
Regeneron Pharmaceuticals, Inc.
clinicaltrials@regeneron.com
18447346643

Study Officials

  • Clinical Trial Management

    Regeneron Pharmaceuticals

    STUDY DIRECTOR

Publication Agreements

PI is Sponsor Employee
No
Restriction Type
OTHER
Restrictive Agreement
Yes

Study Design

Study Type
interventional
Phase
phase 2
Allocation
RANDOMIZED
Masking
NONE
Purpose
TREATMENT
Intervention Model
PARALLEL
Sponsor Type
INDUSTRY
Responsible Party
SPONSOR

Study Record Dates

First Submitted

April 19, 2021

First Posted

April 21, 2021

Study Start

April 29, 2021

Primary Completion

November 21, 2022

Study Completion

November 21, 2022

Last Updated

October 20, 2025

Results First Posted

August 20, 2024

Record last verified: 2025-10

Data Sharing

IPD Sharing
Will share

All Individual Patient Data (IPD) that underlie publicly available results will be considered for sharing

Shared Documents
STUDY PROTOCOL, SAP, ICF, CSR, ANALYTIC CODE
Time Frame
When Regeneron has received marketing authorization from major health authorities (e.g., FDA, European Medicines Agency (EMA), Pharmaceuticals and Medical Devices Agency (PMDA), etc.) for the product and indication, has made the study results publicly available (e.g., scientific publication, scientific conference, clinical trial registry), has the legal authority to share the data, and has ensured the ability to protect participant privacy.
Access Criteria
Qualified researchers can submit a proposal for access to individual patient or aggregate level data from a Regeneron-sponsored clinical trial through Vivli. Regeneron's Independent Research Request Evaluation Criteria can be found at: https://www.regeneron.com/sites/default/files/Regeneron-External-Data-Sharing-Policy-and-Independent-Research-Request-Evaluation-Criteria.pdf
More information

Locations

US(6)