ImmunocompromisedPhase 3NCT05074433
A Study to Evaluate Efficacy and Safety of Casirivimab+Imdevimab (Monoclonal Antibodies) for Prevention of COVID-19 in Immunocompromised Adolescents and Adults
A Phase 3 study testing casirivimab+imdevimab in people with Immunocompromised, run by Regeneron Pharmaceuticals at 67 sites in 2 countries.
Trial summary
The primary objective of the study is to evaluate the effect of casirivimab+imdevimab, compared with placebo, in preventing symptomatic SARS-CoV-2 infection in immunocompromised participants. Read more about this study
- Who is it for?
- Ages 12 years and older
- Conditions the study is for
- Immunocompromised
- What is being tested?
- casirivimab+imdevimab
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 66 participants
- Where
- 67 sitesin 2 countries
- Study dates
- 25 Oct 2021to 18 May 2022
- Phase
- Phase 3
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 12 years and older
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Who may be able to join
- Meets ≥1 of the following criteria:
- Is immunocompromised, including people with transplant, who have cancer, primary immunodeficiencies, HIV, rheumatological disease, autoimmune disease, multiple sclerosis OR
- Currently taking immunosuppressant drugs
- Have been fully vaccinated against COVID-19 or deemed medically ineligible to receive full course of vaccine
- Has documented negative serology/antibody response in an anti-SARS-CoV-2 spike protein IgG clinical test or ≤50 U/mL on the Elecsys® SARS-CoV-2 S Total Ig test
- Tested negative for the COVID-19 virus within 72 hours prior to randomization
Who cannot join
- Weighs <40 kg (only applies to participants ≥12 to <18 years of age)
- Has any signs or symptoms consistent with COVID-19
- Past COVID-19 infection within 90 days prior to randomization
- Planned use of any investigational, authorized, or approved vaccine for COVID-19 within 90 days of the last dose of study drug
- Prior, current, or planned use of any of COVID-19 convalescent plasma, other monoclonal antibodies against SARS-CoV-2 or any COVID-19 treatment
- Is planned to begin immunoglobulin (IVIG) or immunoglobulin (SCIG) therapy, is planned to have a change to existing IVIG or SCIG, or has been on a chronic stable dose of their IVIG or SCIG regimen for less than 90 days prior to screening
Show all 10Show fewer
- Has any known active acute respiratory infection
- Has persistent (refractory to treatment for ≥14 days) bacterial or fungal infection
- Has known allergy or hypersensitivity to components of the study drugs
- NOTE: Other Protocol Defined Inclusion/Exclusion Criteria Apply
Trial locations and contacts
67 sites in 2 countries.
67 sites in 2 countries
United States66 sites
PharmaTex Research, LLC
Amarillo, Texas, 79109
University of Michigan
Ann Arbor, Michigan, 48109
Regeneron Study Site
Atlanta, Georgia, 30322
University Of Colorado
Aurora, Colorado, 80045
Central Texas Clinical Research
Austin, Texas, 78705
Arthritis and Rheumatic Disease Specialties
Aventura, Florida, 33180
Institute of Human Virology
Baltimore, Maryland, 21201
Johns Hopkins Hospital
Baltimore, Maryland, 21287
Laboratory of Clinical Immunology and Microbiology, NIAID
Bethesda, Maryland, 20892
Central Alabama Research
Birmingham, Alabama, 35205
Tufts Medical Center
Boston, Massachusetts, 02111
Regeneron Study Site
Boston, Massachusetts, 02115
Beth Israel Deaconess Medical Center
Boston, Massachusetts, 02215
Maimonides Cancer Center
Brooklyn, New York, 11220
Gabrail Cancer Center Research
Canton, Ohio, 44718
Great Lakes Clinical Trials - Ravenswood
Chicago, Illinois, 60625
Innovative Research of West Florida, Inc.
Clearwater, Florida, 33756
Regeneron Study Site
Cleveland, Ohio, 44195
Miami Valley Hospital
Dayton, Ohio, 45409
Altoona Center for Clinical Research
Duncansville, Pennsylvania, 16635
Midway Immunology and Research Center
Ft. Pierce, Florida, 34982
Spectrum Health
Grand Rapids, Michigan, 49503
Elixia COVID-19
Hollywood, Florida, 33024
Therapeutic Concepts, PA
Houston, Texas, 77004
Houston Methodist Hospital
Houston, Texas, 77030
MD Anderson Cancer Center
Houston, Texas, 77030
Synergy Group Medical,LLC
Houston, Texas, 77087
University of Iowa
Iowa City, Iowa, 52242
West Tennessee Research Institute
Jackson, Tennessee, 38305
Baptist Health Center for Clinical Research
Little Rock, Arkansas, 72205
Regeneron Study Site
Long Beach, California, 90806
Regeneron Study Site
Los Angeles, California, 90033
Cedars-Sinai Medical Center
Los Angeles, California, 90048
University of Wisconsin - Madison
Madison, Wisconsin, 53792
Regeneron Study Site
Marietta, Georgia, 30060
AppleMed Research Group, LLC
Miami, Florida, 33126
De La Cruz Research Center, LLC
Miami, Florida, 33184
Burke Primary Care
Morganton, North Carolina, 28655
Jersey Shore University Medical Center
Neptune City, New Jersey, 07753
Tulane University
New Orleans, Louisiana, 70112
Icahn School of Medicine at Mount Sinai
New York, New York, 10029
Regeneron Study Site
New York, New York, 10032-3729
Memorial Sloan Kettering Cancer Center
New York, New York, 10065
Regeneron Study Site 2
New York, New York, 10065
Regeneron Study Site
North Haven, Connecticut, 06473-2195
University of Nebraska Medical Center
Omaha, Nebraska, 68198
Stanford University
Palo Alto, California, 94304
Penn Prevention Clinical Research Site
Philadelphia, Pennsylvania, 19104
Temple University
Philadelphia, Pennsylvania, 19140
Regeneron Study Site
Providence, Rhode Island, 02903
Regeneron Study Site
Richmond, Virginia, 23219
Mayo Clinic
Rochester, Minnesota, 55905
Regeneron Study Site
Rochester, New York, 14642
University of California
Sacramento, California, 95817
Fred Hutchinson Cancer Research Center
Seattle, Washington, 98109
Regeneron Study Site
Seattle, Washington, 98109
Swedish Medical Center- First Hill
Seattle, Washington, 98122
Regeneron Study Site
Stanford, California, 94305
Regeneron Study Site
Syracuse, New York, 13210
SUNY Upstate Medical University
Syracuse, New York, 13215
University of South Florida
Tampa, Florida, 33606
Holy Name
Teaneck, New Jersey, 07666
Montefiore Medical Center
The Bronx, New York, 10467
Georgetown University
Washington D.C., District of Columbia, 20007
James R Berenson MD Inc.
West Hollywood, California, 90069
Florida Medical Clinic, LLC
Zephyrhills, Florida, 33542
About this study
Official title: A Phase 3, Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Efficacy and Safety of Anti-Spike SARS-CoV-2 Monoclonal Antibodies as Pre-Exposure Prophylaxis to Prevent COVID-19 in Immunocompromised Participants
The primary objective of the study is to evaluate the effect of casirivimab+imdevimab, compared with placebo, in preventing symptomatic SARS-CoV-2 infection in immunocompromised participants.
The secondary objectives of the study are:
- To evaluate the safety and tolerability of repeated SC injections of casirivimab+imdevimab in the study population
- To characterize concentrations of casirivimab and imdevimab in serum over time
- To assess the immunogenicity of casirivimab and imdevimab
- Conditions
- Immunocompromised
- Being tested
- casirivimab+imdevimab, Placebo
- Keywords
- Non-response to COVID-19 vaccination, COVID-19, Immunocompromised, weakened immune system
- Medical subject headings
- COVID-19
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
casirivimab+imdevimabDrug
Also called REGN-COV2, REGN10933, REGN10987, REGEN-COV™
Co-administered sequentially subcutaneous (SC)
PlaceboDrug
Administered SC
| Study group | Role | What they receive |
|---|---|---|
| casirivimab+imdevimab Initial + Q4W | Experimental | Initial subcutaneous (SC) dose, then SC dose every 4 weeks (Q4W) Receives: Drug: casirivimab+imdevimab |
| casirivimab+imdevimab Q4W | Experimental | SC dose Q4W Receives: Drug: casirivimab+imdevimab |
| casirivimab+imdevimab Q12W | Experimental | SC dose every 12 weeks (Q12W) Receives: Drug: casirivimab+imdevimab |
| Placebo | Placebo comparator | SC dose Q4W Receives: Drug: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Cumulative Incidence of Symptomatic (Broad Term), RT-PCR-confirmed SARS-CoV-2 Infection Cases During the EAP
Cumulative incidence of symptomatic (broad term), RT-PCR-confirmed SARS-CoV-2 infection cases during the Efficacy Assessment Period (EAP)
Measured: The EAP was defined as the day from first dose of study drug to day 169 +/- 7 days
Secondary outcomes (11)
Number of Participants With Grade ≥3 Treatment-emergent Adverse Events (TEAEs) During the EAP
Measured: The EAP was defined as the day from first dose of study drug to day 169 +/- 7 days
Number of Participants With Grade ≥3 Treatment-emergent Adverse Events (TEAEs) During the Follow-Up Period
Measured: End of EAP to the end of the Follow-Up Period (Day 169 to 205, approximately ~1 months)
Number of Participants With TEAEs Leading to Study Drug Discontinuation During the EAP
Measured: The EAP was defined as the day from first dose of study drug to day 169 +/- 7 days
Number of Participants With TEAEs Leading to Study Drug Discontinuation During the Follow-Up Period
Measured: End of EAP to the end of the Follow-Up Period (Day 169 to 205, approximately ~1 months)
Number of Participants With Treatment-emergent Serious Adverse Events (SAEs) During the EAP
Measured: The EAP was defined as the day from first dose of study drug to day 169 +/- 7 days
Proportion of Participants With Treatment-emergent Serious Adverse Events (SAEs) During the Follow-Up Period
Measured: End of EAP to the end of the Follow-Up Period (Day 169 to 205, approximately ~1 months)
Incidence of Adverse Events of Special Interest (AESIs) During the EAP
Measured: The EAP was defined as the day from first dose of study drug to day 169 +/- 7 days
Concentration of Casirivimab Over Time
Measured: Up to 28 days postdose for the Q4W groups and 84 days postdose for the Q12 group
Concentration of Imdevimab Over Time
Measured: Up to 28 days postdose for the Q4W groups and 84 days postdose for the Q12 group
Incidence of Anti-drug Antibodies (ADA) Over Time
Measured: Up to 28 days postdose for the Q4W groups and 84 days postdose for the Q12 group
Incidence of Neutralizing Antibodies (NAb) to Each mAb Over Time
Measured: Up to 28 days postdose for the Q4W groups and 84 days postdose for the Q12 group
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted12 Oct 2021
- Study start25 Oct 2021
- Primary completion18 May 2022
- Study completion18 May 2022
Why it stopped: Emerging SARS-CoV2 variants impacting susceptibility to study drug
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Other trials for ImmunocompromisedStudies of the same condition, open and under way.
- More trials run by Regeneron PharmaceuticalsThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 3
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Sequential
- Masking
- Triple blind
- Who is masked
- Participant, Care provider, Investigator
- Enrolment
- 66 participants (actual)
Sponsor and investigators
- Lead sponsor
- Regeneron Pharmaceuticals
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Clinical Trial Management, Study director, Regeneron Pharmaceuticals
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05074433
- Sponsor's protocol ID
- R10933-10987-COV-2176
- Other IDs
- 2021-005222-14
- Status last verified
- Oct 2025
- First submitted
- 8 Oct 2021
- Last updated
- 20 Oct 2025
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Yes: All Individual Patient Data (IPD) that underlie publicly available results will be considered for sharing
Study at a glance
From the registry record, last updated by the sponsor on 20 Oct 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase 3, Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Efficacy and Safety of Anti-Spike SARS-CoV-2 Monoclonal Antibodies as Pre-Exposure Prophylaxis to Prevent COVID-19 in Immunocompromised Participants
- ClinicalTrials.gov ID
- NCT05074433
- Acronym / sponsor ID
- R10933-10987-COV-2176
- Conditions
- Immunocompromised
- Keywords
- Non-response to COVID-19 vaccination, COVID-19, Immunocompromised, weakened immune system
- Phase
- Phase 3
- Study type
- Interventional
- Recruitment status
- TerminatedReason stopped: Emerging SARS-CoV2 variants impacting susceptibility to study drug
- Enrolment
- 66 participants (actual)
- Lead sponsor
- Regeneron PharmaceuticalsIndustry (pharma, biotech, devices)
- Study start
- 25 Oct 2021 (actual)
- Primary completion
- 18 May 2022 (actual)
- Study completion
- 18 May 2022 (actual)
- First posted
- 12 Oct 2021 (actual)
- Results
- Posted 24 Jul 2023
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The primary objective of the study is to evaluate the effect of casirivimab+imdevimab, compared with placebo, in preventing symptomatic SARS-CoV-2 infection in immunocompromised participants.
The secondary objectives of the study are:
- To evaluate the safety and tolerability of repeated SC injections of casirivimab+imdevimab in the study population
- To characterize concentrations of casirivimab and imdevimab in serum over time
- To assess the immunogenicity of casirivimab and imdevimab
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Sequential
- Masking
- Triple blind (participant, care provider, investigator)
- Number of arms
- 4
| Arm | Type | Receives |
|---|---|---|
| casirivimab+imdevimab Initial + Q4W | Experimental | Drug: casirivimab+imdevimabInitial subcutaneous (SC) dose, then SC dose every 4 weeks (Q4W) |
| casirivimab+imdevimab Q4W | Experimental | Drug: casirivimab+imdevimabSC dose Q4W |
| casirivimab+imdevimab Q12W | Experimental | Drug: casirivimab+imdevimabSC dose every 12 weeks (Q12W) |
| Placebo | Placebo comparator | Drug: PlaceboSC dose Q4W |
Who may qualify
- Ages
- 12 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
Key inclusion criteria (6 listed)
- Meets ≥1 of the following criteria:
- Have been fully vaccinated against COVID-19 or deemed medically ineligible to receive full course of vaccine
- Has documented negative serology/antibody response in an anti-SARS-CoV-2 spike protein IgG clinical test or ≤50 U/mL on the Elecsys® SARS-CoV-2 S Total Ig test
- Tested negative for the COVID-19 virus within 72 hours prior to randomization
Key exclusion criteria (10 listed)
- Weighs <40 kg (only applies to participants ≥12 to <18 years of age)
- Has any signs or symptoms consistent with COVID-19
- Past COVID-19 infection within 90 days prior to randomization
- Planned use of any investigational, authorized, or approved vaccine for COVID-19 within 90 days of the last dose of study drug
- Prior, current, or planned use of any of COVID-19 convalescent plasma, other monoclonal antibodies against SARS-CoV-2 or any COVID-19 treatment
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| casirivimab+imdevimabAlso: REGN-COV2, REGN10933, REGN10987, REGEN-COV™Co-administered sequentially subcutaneous (SC) | Drug | casirivimab+imdevimab Initial + Q4W, casirivimab+imdevimab Q12W, casirivimab+imdevimab Q4W |
| PlaceboAdministered SC | Drug | Placebo |
Primary outcome
Cumulative Incidence of Symptomatic (Broad Term), RT-PCR-confirmed SARS-CoV-2 Infection Cases During the EAP
Time frame: The EAP was defined as the day from first dose of study drug to day 169 +/- 7 days
Cumulative incidence of symptomatic (broad term), RT-PCR-confirmed SARS-CoV-2 infection cases during the Efficacy Assessment Period (EAP)
11 secondary outcomes
Number of Participants With Grade ≥3 Treatment-emergent Adverse Events (TEAEs) During the EAP
Time frame: The EAP was defined as the day from first dose of study drug to day 169 +/- 7 days
Number of Participants With Grade ≥3 Treatment-emergent Adverse Events (TEAEs) During the Follow-Up Period
Time frame: End of EAP to the end of the Follow-Up Period (Day 169 to 205, approximately ~1 months)
Number of Participants With TEAEs Leading to Study Drug Discontinuation During the EAP
Time frame: The EAP was defined as the day from first dose of study drug to day 169 +/- 7 days
Number of Participants With TEAEs Leading to Study Drug Discontinuation During the Follow-Up Period
Time frame: End of EAP to the end of the Follow-Up Period (Day 169 to 205, approximately ~1 months)
Number of Participants With Treatment-emergent Serious Adverse Events (SAEs) During the EAP
Time frame: The EAP was defined as the day from first dose of study drug to day 169 +/- 7 days
Proportion of Participants With Treatment-emergent Serious Adverse Events (SAEs) During the Follow-Up Period
Time frame: End of EAP to the end of the Follow-Up Period (Day 169 to 205, approximately ~1 months)
Incidence of Adverse Events of Special Interest (AESIs) During the EAP
Time frame: The EAP was defined as the day from first dose of study drug to day 169 +/- 7 days
Concentration of Casirivimab Over Time
Time frame: Up to 28 days postdose for the Q4W groups and 84 days postdose for the Q12 group
Concentration of Imdevimab Over Time
Time frame: Up to 28 days postdose for the Q4W groups and 84 days postdose for the Q12 group
Incidence of Anti-drug Antibodies (ADA) Over Time
Time frame: Up to 28 days postdose for the Q4W groups and 84 days postdose for the Q12 group
Incidence of Neutralizing Antibodies (NAb) to Each mAb Over Time
Time frame: Up to 28 days postdose for the Q4W groups and 84 days postdose for the Q12 group
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 20 Oct 2025.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Individual participant dataSharing planned: Yes. All Individual Patient Data (IPD) that underlie publicly available results will be considered for sharing
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Clinical Trial Management study director
Regeneron Pharmaceuticals
67 sites in 2 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 3 study testing casirivimab+imdevimab in people with Immunocompromised, run by Regeneron Pharmaceuticals at 67 sites in 2 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 6 inclusion and 10 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: stopped early, as of the sponsor's last update on 20 Oct 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 67 sites in United States, Mexico. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
Yes. Results are posted in the registry (first posted 24 Jul 2023). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Cumulative Incidence of Symptomatic (Broad Term), RT-PCR-confirmed SARS-CoV-2 Infection Cases During the EAP (time frame: The EAP was defined as the day from first dose of study drug to day 169 +/- 7 days). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 20 Oct 2025.