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REGN-COV2 binding SARS-CoV-2 spike protein.png
REGN10933 (blue) and REGN10987 (orange) bound to SARS-CoV-2 spike protein (pink). From PDB: 6VSB, 6XDG​.
Combination of
CasirivimabMonoclonal antibody against spike protein of SARS-CoV-2
ImdevimabMonoclonal antibody against spike protein of SARS-CoV-2
Clinical data
Other namesREGN-COV2
License data
Routes of
ATC code
  • None
Legal status
Legal status
CAS Number

Casirivimab/imdevimab is an experimental medicine developed by the American biotechnology company Regeneron Pharmaceuticals. It is an artificial "antibody cocktail" designed to produce resistance to the SARS-CoV-2 coronavirus responsible for the COVID-19 pandemic.[3][4] It consists of a mixture of two monoclonal antibodies, casirivimab (REGN10933) and imdevimab (REGN10987).[5][6] The combination of two antibodies is intended to prevent mutational escape.[7]


In a clinical trial of people with COVID-19, casirivimab and imdevimab, administered together, were shown to reduce COVID-19-related hospitalization or emergency room visits in people at high risk for disease progression within 28 days after treatment when compared to placebo.[2] The safety and effectiveness of this investigational therapy for use in the treatment of COVID-19 continues to be evaluated.[2]

The data supporting the emergency use authorization (EUA) for casirivimab and imdevimab are based on a randomized, double-blind, placebo-controlled clinical trial in 799 non-hospitalized adults with mild to moderate COVID-19 symptoms.[2] Of these participants, 266 received a single intravenous infusion of 2,400 milligrams casirivimab and imdevimab (1,200 mg of each), 267 received 8,000 mg casirivimab and imdevimab (4,000 mg of each), and 266 received a placebo, within three days of obtaining a positive SARS-CoV-2 viral test.[2]

The prespecified primary endpoint for the trial was time-weighted average change in viral load from baseline.[2] Viral load reduction in participants treated with casirivimab and imdevimab was larger than in participants treated with placebo at day seven.[2] However, the most important evidence that casirivimab and imdevimab administered together may be effective came from the predefined secondary endpoint of medically attended visits related to COVID-19, particularly hospitalizations and emergency room visits within 28 days after treatment.[2] For participants at high risk for disease progression, hospitalizations and emergency room visits occurred in 3% of casirivimab and imdevimab-treated participants on average compared to 9% in placebo-treated participants.[2] The effects on viral load, reduction in hospitalizations and ER visits were similar in participants receiving either of the two casirivimab and imdevimab doses.[2]

As of September 2020, REGN-COV2 is being evaluated as part of the RECOVERY Trial.[8]


On 21 November 2020, the U.S. Food and Drug Administration (FDA) issued an emergency use authorization (EUA) for casirivimab and imdevimab to be administered together for the treatment of mild to moderate COVID-19 in people twelve years of age or older weighing at least 40 kilograms (88 lb) with positive results of direct SARS-CoV-2 viral testing and who are at high risk for progressing to severe COVID-19.[2] This includes those who are 65 years of age or older or who have certain chronic medical conditions.[2] Casirivimab and imdevimab must be administered together by intravenous (IV) infusion.[2]

Casirivimab and imdevimab are not authorized for people who are hospitalized due to COVID-19 or require oxygen therapy due to COVID-19.[2] A benefit of casirivimab and imdevimab treatment has not been shown in people hospitalized due to COVID-19.[2] Monoclonal antibodies, such as casirivimab and imdevimab, may be associated with worse clinical outcomes when administered to hospitalized people with COVID-19 requiring high flow oxygen or mechanical ventilation.[2]

The EUA was issued to Regeneron Pharmaceuticals Inc.[2]

On 1 February 2021, the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) started a rolling review of data on the REGN‑COV2 antibody combination (casirivimab/imdevimab), which is being co-developed by Regeneron Pharmaceuticals, Inc. and F. Hoffman-La Roche, Ltd (Roche) for the treatment and prevention of COVID‑19.[9]


Although Regeneron is headquartered in Tarrytown, New York (near New York City), REGN-COV2 is manufactured at the company's primary U.S. manufacturing facility in Rensselaer, New York (near the state capital at Albany).[10] In September 2020, to free up manufacturing capacity for REGN-COV2, Regeneron began to shift production of its existing products from Rensselaer to the Irish city of Limerick.[11]

Regeneron has a deal in place with Hoffmann-La Roche to manufacture and market REGN-COV2 outside the United States.[12]

On 2 October 2020, Regeneron Pharmaceuticals announced that US President Donald Trump had received "a single 8 gram dose of REGN-COV2" after testing positive for SARS-CoV-2.[13][14] The drug was provided by the company in response to a "compassionate use" (temporary authorization for use) request from the president's physicians.[13]

See also[edit]

  • Bamlanivimab, another monoclonal antibody treatment for COVID-19.


  1. ^ "Casirivimab injection, solution, concentrate Imdevimab injection, solution, concentrate". DailyMed. Retrieved 28 December 2020.
  2. ^ a b c d e f g h i j k l m n o p q "Coronavirus (COVID-19) Update: FDA Authorizes Monoclonal Antibodies for Treatment of COVID-19". U.S. Food and Drug Administration (FDA) (Press release). 21 November 2020. Retrieved 21 November 2020. This article incorporates text from this source, which is in the public domain.
  3. ^ Kelland K (2020-09-14). "Regeneron's antibody drug added to UK Recovery trial of COVID treatments". Reuters. Retrieved 2020-09-14.
  4. ^ "Regeneron's COVID-19 Response Efforts". Regeneron Pharmaceuticals. Retrieved 2020-09-14.
  5. ^ Morelle R (2020-09-14). "Antibody treatment to be given to Covid patients". BBC News Online. Retrieved 2020-09-14.
  6. ^ "Safety, Tolerability, and Efficacy of Anti-Spike (S) SARS-CoV-2 Monoclonal Antibodies for Hospitalized Adult Patients With COVID-19". ClinicalTrials. 2020-09-03. Retrieved 14 September 2020.
  7. ^ Baum A, Fulton BO, Wloga E, Copin R, Pascal KE, Russo V, et al. (August 2020). "Antibody cocktail to SARS-CoV-2 spike protein prevents rapid mutational escape seen with individual antibodies". Science. 369 (6506): 1014–1018. doi:10.1126/science.abd0831. PMC 7299283. PMID 32540904.
  8. ^ "RECOVERY COVID-19 phase 3 trial to evaluate Regeneron's REGN-COV2 investigational antibody cocktail in the UK". Recovery Trial. Retrieved 2020-09-14.
  9. ^ "EMA starts rolling review of REGN‑COV2 antibody combination (casirivimab / imdevimab)". European Medicines Agency (EMA). 1 February 2021. Retrieved 1 February 2021. Text was copied from this source which is © European Medicines Agency. Reproduction is authorized provided the source is acknowledged.
  10. ^ Williams, Stephen (October 3, 2020). "Experimental drug given to President made locally". The Daily Gazette.
  11. ^ Stanton, Dan (September 11, 2020). "Manufacturing shift to Ireland frees up US capacity for Regeneron's COVID antibodies". BioProcess International.
  12. ^ "Roche and Regeneron link up on a coronavirus antibody cocktail". CNBC. 2020-08-19. Retrieved 2020-09-14.
  13. ^ a b Thomas K (2020-10-02). "President Trump Received Experimental Antibody Treatment". The New York Times. ISSN 0362-4331. Retrieved 2020-10-02.
  14. ^ Hackett DW (2020-10-03). "8-Gram Dose of COVID-19 Antibody Cocktail Provided to President Trump". Archived from the original on 2020-10-03.

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