COVID-19 Study Assessing the Safety and Tolerability of Co-Formulated Anti-Spike (S) SARS-CoV-2 Monoclonal Antibodies (Casirivimab+Imdevimab) in Adult Volunteers

A Phase 1, Randomized, Open-Label Study Assessing the Safety and Tolerability of Co-Formulated Anti-Spike (S) SARS-CoV-2 Monoclonal Antibodies (Casirivimab+Imdevimab) in Adult Volunteers

The primary objective of the study is to assess the safety and tolerability of co-formulated subcutaneous (SC) and intravenous (IV) casirivimab+imdevimab

The secondary objectives of the study are to:

• Explore variability in the drug concentration profiles of casirivimab and imdevimab after co-formulated subcutaneous (SC) or intravenous (IV) administration
• Characterize the immunogenicity of casirivimab and imdevimab in serum over time

Study Overview

• Status: Completed
• Conditions: Healthy; Chronic Stable Illness
• Intervention / Treatment: Drug: Casirivimab+Imdevimab

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

Contacts and Locations

Study Locations

• United States
  • Florida
    • Miami, Florida, United States, 33186
      • Regeneron Study Site
    • Winter Park, Florida, United States, 32789
      • Regeneron StudySite

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 65 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

Key Inclusion Criteria:

1. Is healthy, or has chronic medical condition(s) that per the opinion of the investigator is (are) stable, well-controlled, and not likely to require medical intervention through the end of study
2. Does not require medication(s) for co-morbid condition, or has received stable medication(s) for co-morbid condition(s) for at least 6 months prior to screening
3. Weighs between ≥60 kg and ≤100 kg at the time of screening
4. Has SARS-CoV-2-negative reverse-transcriptase polymerase chain reaction (RT-PCR) from a sample collected ≤72 hours prior to randomization, using local assay and sample collection and assay standards
5. Has completed a full course of COVID-19 vaccination more than 6 weeks prior to randomization

Key Exclusion Criteria:

1. Has active respiratory or non-respiratory symptoms consistent with COVID-19 in the opinion of the Investigator
2. Has recent SARS-CoV-2 infection that resolved within 6 weeks prior to randomization
3. Prior use of casirivimab+imdevimab at any time prior to randomization
4. Prior, current, or planned use during the study of any of the following treatments: COVID-19 convalescent plasma, other monoclonal antibodies against SARS-CoV-2 (eg, bamlanivimab and etesevimab, sotrovimab), intravenous immunoglobulin (any indication), or any other investigational, authorized, or approved agent intended for COVID-19 treatment or prevention (with the exception of COVID-19 vaccines)
5. Treatment with another investigational drug in the last 30 days or within 5 half-lives of the investigational drug, whichever is longer, prior to screening
6. Body mass index (BMI) ≥28 kg/m2
7. Medically-attended acute illness, systemic antibiotics use, or hospitalization for any reason within 30 days prior to screening
8. Acute exacerbation of a chronic pulmonary condition (eg, chronic obstructive pulmonary disease [COPD], asthma exacerbations) in the past 6 months prior to screening
9. Uncontrolled hypertension, in the opinion of the investigator
10. History of heart failure hospitalization, diagnosis of a myocardial infarction, stroke, transient ischemic attack, unstable angina, percutaneous or surgical revascularization procedure (coronary, carotid, or peripheral vascular), or intracardiac device placement (eg, pacemaker) within 12 months prior to screening
11. Cancer requiring treatment currently or in the past 5 years, except for non-melanoma skin cancer or cervical/anus in-situ
12. Is pregnant at screening

Note: Other protocol-defined Inclusion/ Exclusion Criteria apply

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Co-formulated casirivimab+imdevimab SC; Randomized 1:1	Drug: Casirivimab+Imdevimab; Randomized 1:1 for intravenous (IV) or subcutaneous (SC) administration; Other Names: REGN-COV2; Casirivimab; Imdevimab; REGEN-COV™; Ronapreve™
Experimental: Co-formulated casirivimab+imdevimab IV; Randomized 1:1	Drug: Casirivimab+Imdevimab; Randomized 1:1 for intravenous (IV) or subcutaneous (SC) administration; Other Names: REGN-COV2; Casirivimab; Imdevimab; REGEN-COV™; Ronapreve™

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Targeted grade ≥3 treatment-emergent adverse events (TEAEs)	Through end of study, approximately 16 weeks
Grade ≥3 injection-site reactions (ISRs)	Through end of study, approximately 16 weeks
Grade ≥2 infusion-related reactions (IRRs)	Through end of study, approximately 16 weeks
Grade ≥2 hypersensitivity reactions	Through end of study, approximately 16 weeks
Serious adverse events (SAEs)	Through end of study, approximately 16 weeks

Secondary Outcome Measures

Outcome Measure	Time Frame
Concentrations of casirivimab and imdevimab in serum over time	Up to 16 weeks
Incidence and titer of anti-drug antibodies (ADA) to casirivimab and imdevimab	Up to 16 weeks
Incidence of neutralizing antibodies (NAb) to casirivimab and imdevimab	Up to 16 weeks

Collaborators and Investigators

• Sponsor: Regeneron Pharmaceuticals
• Investigators: Study Director: Clinical Trial Management, Regeneron Pharmaceuticals

Study record dates

Study Major Dates

• Study Start (Actual): January 7, 2022
• Primary Completion (Actual): June 3, 2022
• Study Completion (Actual): June 3, 2022

Study Registration Dates

• First Submitted: January 4, 2022
• First Submitted That Met QC Criteria: January 4, 2022
• First Posted (Actual): January 6, 2022

Study Record Updates

• Last Update Posted (Estimated): October 14, 2025
• Last Update Submitted That Met QC Criteria: October 9, 2025
• Last Verified: October 1, 2025

More Information

Terms related to this study

• Keywords: Coronavirus disease 2019 (COVID-19); Severe acute respiratory syndrome coronavirus 2 (SARS-COV-2)
• 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; casirivimab and imdevimab drug combination; casirivimab; imdevimab
• Other Study ID Numbers: R10933-10987-COV-2179

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: All Individual Patient Data (IPD) that underlie publicly available results will be considered for sharing
• IPD Sharing 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.
• IPD Sharing 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
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF; ANALYTIC_CODE; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No