Casirivimab-Imdevimab

Casirivimab-imdevimab, or REGN-COV2, consists of a mixture of two monoclonal antibodies, casirivimab (REGN10933) and imdevimab (REGN10987). The antibody mixture received emergency approval in the U.S. by the Food and Drug Administration (FDA) in November 2020 for the treatment of mild to moderate COVID-19 disease.

This approval is limited to individuals at least 12 years of age and at least 40 kilograms of body weight who have tested positive for SARS-CoV-2 and are at high risk of developing a severe course of the disease. This includes patients who are 65 years of age or older or have certain chronic pre-existing conditions.

Limitations of Benefit and Potential Risk in Patients with Severe COVID-19: Benefit of treatment with casirivimab and imdevimab has not been observed in patients hospitalized for COVID-19. However, treatment outcomes with casirivimab -Imdevimab may be associated with worse clinical outcomes when the antibody mixture is administered to hospitalized patients who have high oxygen flux due to COVID-19 or who require mechanical ventilation. Therefore, casirivimab and imdevimab are not approved for use in these patients.

The study results are based on a randomized, double-blind, placebo-controlled clinical trial in 799 non-hospitalized adults with mild to moderate COVID-19 symptoms. Of these participants, 266 received an intravenous infusion of 1200 milligrams each of casirivimab and imdevimab within three days of testing positive for COVID-19, 267 participants received 4000 mg each of casirivimab and imdevimab, and 266 participants received placebo. Evidence showed that casirivimab and imdevimab administered together reduced COVID-19-related hospitalizations or emergency room visits in people at high risk for disease progression within 28 days of treatment compared with placebo.

Serious adverse events (SAEs) have not been associated with study drug. There is a possibility of a severe hypersensitivity reaction, including anaphylaxis, when casirivimab and imdevimab are administered. Signs and symptoms of infusion-related reactions may include fever, chills, nausea, headache, bronchospasm, hypotension, angioedema, throat irritation, rash including urticaria, pruritus, myalgia, and/or dizziness. If an infusion-related reaction occurs, consider slowing or discontinuing the infusion and administer appropriate medications and/or supportive measures.

The 2019 coronavirus disease pandemic (COVID-19) presented a number of challenges and opportunities for the healthcare system in 2020 and will continue to do so in 2021. By the end of November 2020, two anti-SARS-CoV antibody products, bamlanivimab and casirivimab-imdevimab, had been approved by the US Food and Drug Administration (FDA) for emergency use (Aschenbrenner DS 2021). The antibodies levilimab and itolizumab have been registered for emergency use in Russia and India, respectively, for the treatment of COVID-19 (Kaplon H et al. 2021).

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