A formulation of SARS-CoV-2 Spike protein-neutralising antibodies.

Phase of research

Emergency use authorization

How it helps


Drug status


Supporting references
Contradictory references
AI-suggested references
Clinical trials

General information

REGEN-COV (Ronapreve) is a SARS-CoV-2 (Spike) neutralising antibody cocktail. It contains equal amounts of casirivimab and imdevimab antibodies (Weinreich et al., 2020).

On November 21, 2020, the FDA issued an Emergency Use Authorization (EUA)* for emergency use of REGEN-COV (casirivimab and imdevimab,
administered together) for the treatment of mild to moderate COVID-19 in adults and pediatric patients (12 years of age and older weighing at least 40 kg) with positive results of direct SARS-CoV-2 viral testing, and who are at high risk for progressing to severe COVID-19 and/or hospitalization. 

On March 23, 2021, Regeneron Pharmaceuticals, Inc. (NASDAQ: REGN) announced positive topline results from the largest trial to date assessing a COVID-19 treatment in infected non-hospitalized patients. The Phase 3 trial shows that the REGEN-COV™ (casirivimab with imdevimab) antibody cocktail reduced hospitalization or death by 70%. 

On August 20, 2021, the MHRA has issued a Conditional Marketing Authorisation for REGN-COV2 (Ronapreve) in Great Britain and a temporary regulation authorisation for Northern Ireland.

Ronapreve has been authorized for the treatment or prevention of COVID-19 in people aged 12 years and older weighing at least 40 kilograms in the EU (EMA).

*FDA has revoked the authorization for bamlanivimab and etesevimab based on the high Omicron prevalence in all U.S. regions.

REGEN-COV on DrugBank
REGEN-COV on Wikipedia



Marketed as



Supporting references

Link Tested on Impact factor Notes Publication date
REGN-COV2, a Neutralizing Antibody Cocktail, in Outpatients with Covid-19
Spike protein Phase II clinical trial Phase I clinical trial Randomized controlled double-blind trial Antibody Mixed substance
Outpatients 74.70

The antibody cocktail was generally well tolerated and reduced viral load in COVID-19 outpatients, especially those with high viral loads at baseline and patients whose immune response had not been initiated at the time of antibody administration. Sample size: 84 (high dose) + 80 (low dose) + 88 placebo (completed the trial). Dosage: 2.4 g (low) or 8 g (high). Endpoints: Change in viral load; proportion of patients with a COVID-19-related hospital visit by day 29.

In vitro and in vivo preclinical studies predict REGEN-COV protection against emergence of viral escape in humans
Preprint Antibody
HEK293T cells, hamsters

This study demonstrates that a combination of noncompeting antibodies not only provides full coverage against currently circulating variants but also protects against emergence of new such variants and their potential seeding into the population in a clinical setting.

SARS-CoV-2 variants B.1.351 and P.1 escape from neutralizing antibodies
Spike protein RNA Small molecule Peptide In vitro Antibody Mixed substance
Caco-2 cells; Vero cells; Sera of vaccinated individuals; (VSV) SARS-CoV-2 Spike-pseudotyped virus (WT, B.1.1.7, B.1.351, ant P.1 variants) 38.64

REGN-COV2 displayed in vitro inhibition of SARS-CoV-2 Spike-pseudotyped virus infection for all tested emergent Spike variants (B.1.1.7, B.1.351, and P.1).

Compassionate use of REGN-COV2 in the treatment of COVID-19 in a patient with impaired humoral immunity
Spike protein IL-1 Protein factor Case report Antibody Mixed substance
An X-linked agammaglobulinaemia patient

In a patient with X-linked agammaglobulinemia, clinical/immunological response to anakinra was not satisfactory. Long-term immunosuppression led to a secondary pulmonary infection. Administration of REGN-COV2 formulation led to SARS-CoV-2 PCR negativity and COVID-19 convalescence. Sample size: 1. Dosage: 1200 mg of REGN10933 and 1200 mg of RGN10987. 

Cocktail of REGN Antibodies Binds More Strongly to SARS-CoV-2 Than Its Components, but the Omicron Variant Reduces Its Neutralizing Ability
Spike protein Spike variant Protein factor Antibody In silico
In silico 2.99

The combined formulation (REGEN-COV) is predicted to display synergy of its components in RBD-binding capacity. 

REGN-COV2 antibodies prevent and treat SARS-CoV-2 infection in rhesus macaques and hamsters
Spike protein Protein factor Animal model Antibody
Syrian golden hamsters; rhesus macaques; SARS-CoV-2 isolate USA-WA1/2020 47.73

The antibody cocktail administered prophylactically or therapeutically reduced viral loads in the lower and the upper respiratory tracts and mitigated pathological changes in rhesus macaques. Alleviation of weight loss, lung pathology and lung viral loads were observed in a hamster model. 

Monoclonal antibody-mediated neutralization of SARS-CoV-2 in an IRF9-deficient child
Spike protein Protein factor Children Case report Antibody Mild severity
An IRF9-deficient child 11.21

The antibody was administered in a child with inborn deficiency in interferon response. The treatment led to a positive clinical outcome. Sample size: 1. Dosage: 600 mg IV. 

Compassionate Use of REGEN-COV® in Patients With Coronavirus Disease 2019 (COVID-19) and Immunodeficiency-Associated Antibody Disorders
Spike protein Protein factor Antibody Cohort study
Patients with immunodeficiency-associated antibody disorders 9.08

Most of the Immunodeficient patients with persisting COVID-19 treated with the antibody cocktail experienced rapid viral clearance and clinical improvement. Serious adverse reactions were mostly unlikely to be treatment-related. Sample size: 64. 

REGEN-COV Antibody Combination and Outcomes in Outpatients with Covid-19
Spike protein Outpatients Protein factor Phase III clinical trial Randomized controlled double-blind trial Antibody Moderate severity Mild severity
Outpatients with risk factors 91.25

Compared to placebo, early treatment with the antibody cocktail in patients with risk factors for COVID-19 progression into a severe disease significantly reduced COVID-19 related hospitalization or death by day 29. The treatment also reduced the median time to the resolution of symptoms and reduced viral load faster. Severe adverse reactions were more frequent in the placebo groups. Sample size: 1355 + 1341 placebo (2400 mg group) and 736 + 748 placebo (1200 mg group) + 10122 (8000 mg - only certain analyses). Dosage: (8000 mg,) 2400 mg or 1200 mg IV. Main outcome: Hospitalization or all-cause death through day 29.

Subcutaneous REGEN-COV Antibody Combination to Prevent Covid-19
Spike protein Outpatients Asymptomatic Protein factor Phase III clinical trial Randomized controlled double-blind trial Antibody
Individuals (≥12 years of age) with recent household contact with a SARS-CoV-2 positive person 91.25

Compared to placebo, early subcutaneous administration of the antibody cocktail in individuals with household contact with SARS-CoV-2 positive persons led to significant decrease of rate of symptomatic COVID-19. The symptomatic COVID-19 and the duration of high viral loads in the treated individuals, if present, were significantly shorter. Sample size: 753 + 752 placebo. Dosage: 12000 mg subcutaneously. Main outcome: Symptomatic COVID-19 in 28 days.

Outcomes of pregnant patients treated with REGEN-COV during the COVID-19 pandemic
Spike protein Asymptomatic Protein factor Antibody Mild severity Cohort study
Pregnant patients 8.66

The treatment of pregnant women was safe. Although its efficacy was not statistically significant, based on the results and other observations, the author advocate for the use of the antibody cocktail in pregnant patients. Sample size: 36 + 50 control. Main outcome: Perinatal outcomes, safety, and the clinical course of COVID-19.

High titer of antibody against the SARS-CoV-2 spike protein among patients receiving neutralizing
Spike protein Protein factor Antibody Cohort study

From a serological point of view, REGEN-COV provides a therapeutic and prophylactic benefit, which is also supported by a high titer of IgGSP (immunoglobulin targeting spike protein).

REGEN-COV antibody combination in patients with lymphoproliferative malignancies and SARS-CoV-2 infection
Spike protein Protein factor Case series Antibody
Patients with lymphoproliferative diseases

Early treatment with REGEN-COV may prevent clinical deterioration in SARS-CoV-2 infection leading to the development of COVID-19 in hematological patients. The effectiveness of the drugs varies depending on the variants of the virus (especially B.1.1.529). Sample size: 15. Dosage: Single infusion of casirivimab (600 mg) and imdevimab (600 mg). 

Effectiveness of REGEN-COV antibody combination in preventing severe COVID-19 outcomes
Spike protein Spike variant Protein factor Antibody Cohort study
High-risk patients

REGEN-COV treatment has been shown to be effective in high-risk patients. Sample size: 696 + 696 control. Dosage: 1200 mg (casirivimab + imdevimab). 

Safety of casirivimab/imdevimab administration in a SARS-CoV-2 positive maintenance dialysis patient in Japan
Spike protein Protein factor Case report Antibody
50-yeas-old African man on maintenance dialysis

REGEN-COV can be given safely to patients on dialysis who have severe disease and do not need extra oxygen. Sample size: 1. Dosage: 1200 mg REGEN-COV on day 2. and 1200 mg/10 mL REGEN-COV dissolved in 100 mL saline for 30 min after dialysis. 

Use of REGEN-COV in children after heart transplantation for treatment and post-exposure prophylaxis of COVID-19
Spike protein Protein factor Children Case series Antibody
Paediatric heart transplant patients

Pediatric heart transplant patients were able to tolerate REGEN-COV without experiencing any complications, and no changes to their immunosuppressive treatment were required. Sample size: 6. 

The monoclonal antibody combination REGEN-COV protects against SARS-CoV-2 mutational escape in preclinical and human studies
Spike protein Spike variant Protein factor Animal model In vitro Antibody
African green monkey kidney cells (Vero, ATCC CCL-81), Vero clone E6 (Vero E6, ATCC CRL-1586), hamsters and human embryonic kidney cells (293T, ATCC CRL-3216)

Based on in vitro, animal model, and observational data, the antibody cocktail was effective against all variants tested and no escape mutations were observed. Sample size: 1000. 

Effectiveness of REGEN‐COV antibody cocktail against the B.1.617.2 (delta) variant of SARS‐CoV‐2: A cohort study
Spike protein Spike variant Protein factor Antibody Cohort study
High-risk patients

Patients who are at high risk for SARS-CoV-2 infection and were treated with the REGEN-COV antibody cocktail, even if infected with the Delta variant, had quicker symptom resolution and lower levels of the virus in their body. Sample size: 208 + 78 control. Dosage: 600 mg casirivimab + imdevimab/100 ml saline. 

Successful Clearance of 300 Day SARS-CoV-2 Infection in a Subject with B-Cell Depletion Associated Prolonged (B-DEAP) COVID by REGEN-COV Anti-Spike Monoclonal Antibody Cocktail
Spike protein Protein factor Cancer Case report Antibody
59-year-old male with obesity, hypertension and hypothyroidism

270 days after the first diagnosis, treatment with REGEN-COV proved to be effective. After being vaccinated with the Pfizer-BioNTech vaccine against COVID-19, the virus was completely eliminated within the following month. Sample size: 1. Dosage: The first dose of 2.4 g, after that at a higher dose of 8 g (4 g for each of casirivimab and of imdevimab) was infused six weeks later. 

Casirivimab-Imdevimab (REGN-COV2) for Mild to Moderate SARS-CoV-2 Infection in Kidney Transplant Recipients
Spike protein Protein factor Antibody Moderate severity Mild severity Cohort study
Kidney transplant recipients

Administering REGN-COV2 in a timely manner to kidney transplant recipients who cannot receive or have a weakened antibody response to vaccinations, may help prevent them from developing severe illness if they test positive for COVID-19. Sample size: 14. Dosage: A single-dose infusions of casirivimab 1200 mg and imdevimab 1200 mg. 

Neutralizing Monoclonal Antibody Treatment Reduces Hospitalization for Mild and Moderate Coronavirus Disease 2019 (COVID-19): A Real-World Experience 
Spike protein Protein factor Antibody Moderate severity Mild severity Cohort study

Treatment with monoclonal antibody led to a decrease in hospital usage, particularly if administered within a few days after the onset of symptoms. Sample size: 707 + 1709 control. Main outcome: Hospitalization with a diagnosis of COVID-19 until the 30th day.


AI-suggested references

Link Publication date
REGN-COV2 antibody cocktail in patients with SARS-CoV-2: Observational study from a single institution in Japan.
Editorial: Post-Exposure Prophylactic Neutralizing Monoclonal Antibodies to SARS-CoV-2 for Individuals at High Risk for COVID-19
Prospective mapping of viral mutations that escape antibodies used to treat COVID-19
Neutralizing Monoclonal Antibody Treatment Reduces Hospitalization for Mild and Moderate COVID-19: A Real-World Experience
Antibody escape and global spread of SARS-CoV-2 lineage A.27
Successful Treatment of Persistent Coronavirus Disease 2019 Infection in a Patient With Hypogammaglobulinemia With REGN-COV2: A Case Report.
Effectiveness of neutralizing antibody cocktail in hemodialysis patients: a case series of 20 patients treated with or without REGN-COV2
Casirivimab/Imdevimab: First Approval
Development and application of therapeutic antibodies against COVID-19
Anti-SARS-CoV-2 neutralizing monoclonal antibodies: clinical pipeline
Fruitful Neutralizing Antibody Pipeline Brings Hope To Defeat SARS-Cov-2
Emerging antibody-based therapeutics against SARS-CoV-2 during the global pandemic.
Duration of infectious viral shedding in patients with mild to moderate COVID-19 treated with REGN-CoV2
Compassionate Use of REGEN-COV in Patients with COVID-19 and Immunodeficiency-Associated Antibody Disorders
Thermodynamic and structural insights into the repurposing of drugs that bind to SARS-CoV-2 main protease
Melatonin and REGN-CoV2 combination as a vaccine adjuvant for Omicron variant of SARS-CoV-2
Clinical Effectiveness of REGN-COV2 in Patients with COVID-19 in Japan: A Retrospective Cohort Study with a Bayesian Inference
Persistent SARS-CoV-2 infection in patients with secondary antibody deficiency: successful clearance following combination casirivimab and imdevimab (REGN-COV2) monoclonal antibody therapy
Neutralizing antibodies against SARS-CoV-2: current understanding, challenge and perspective.

Clinical trials

ID Title Status Phase Start date Completion date
NCT04617535 Compassionate Use of REGN-COV2 for the Treatment of COVID-19 Available Jan/01/1970 Jan/01/1970
  • Alternative id - R10933-10987-COV
  • Interventions - Drug: REGN10933+REGN10987 combination therapy
  • Study type - Expanded Access:Individual Patients
  • Study results - No Results Available
  • Locations -
  • Study designs -
  • Enrollment -
  • Age - Child, Adult, Older Adult
  • Outcome measures -