The Medical Letter on Drugs and Therapeutics
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Bamlanivimab and Etesevimab for Post-Exposure Prophylaxis of COVID-19
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 Select a term to see related articles  bamlanivimab   casirivimab   COVID-19   etesevimab   imdevimab   REGEN-COV 

In February 2021, the FDA issued an Emergency Use Authorization (EUA) for the investigational monoclonal antibodies bamlanivimab and etesevimab (Lilly) for use together to treat mild to moderate COVID-19 in persons ≥12 years old who weigh ≥40 kg and are at high risk of progression to severe disease or hospitalization.1 The FDA has now expanded this EUA to allow use of the antibodies together for post-exposure prophylaxis of COVID-19 in such persons if they are not fully vaccinated against COVID-19 or are unlikely to have an adequate immune response to full vaccination and have been in close contact with a SARS-CoV-2-infected individual or are likely to be exposed to SARS-CoV-2 in the setting of an institutional outbreak (see Table 1).2 Bamlanivimab plus etesevimab is the second monoclonal antibody combination to receive an EUA for post-exposure prophylaxis of COVID-19; casirivimab plus imdevimab (REGEN-COV) was authorized earlier.3

ELIGIBILITY — In May 2021, the FDA expanded the criteria by which a patient with COVID-19 can be considered at high risk for disease progression. All persons ≥12 years old who are overweight, pregnant, or have cardiovascular disease, hypertension, or chronic respiratory disease are now considered high-risk (see Table 2).4

CLINICAL STUDIES — In an unpublished double-blind trial (BLAZE-2 Part 1; summarized in the FDA Fact Sheet), 966 SARS-CoV-2-negative residents or staff of skilled nursing facilities where a confirmed SARS-CoV-2 infection occurred were randomized to receive a single dose of bamlanivimab 2800 mg (without etesevimab) or placebo.

The risk of symptomatic COVID-19 within 8 weeks of randomization, the primary endpoint, was significantly lower in patients who received bamlanivimab than in those who received placebo in both the overall population (8.5% vs 15.2%; number needed to treat [NNT] 15.1; adjusted OR 0.43 [95% CI 0.28-0.68]) and the prespecified subgroup of nursing facility residents (8.9% vs 22.5%; NNT 7.4; adjusted OR 0.20 [95% CI 0.08-0.49]). There were no deaths due to COVID-19 in the bamlanivimab group versus 4 in the placebo group.2,5

No data on the use of bamlanivimab plus etesevimab for post-exposure prophylaxis of COVID-19 are available. Because the combination has greater antiviral activity than bamlanivimab alone, the FDA presumed it to be effective based on the results of BLAZE-2 Part 1. No clinical trials have compared bamlanivimab plus etesevimab with casirivimab plus imdevimab.

ADVERSE EFFECTS — Infusion-related reactions and anaphylaxis have been reported with use of bamlanivimab plus etesevimab.

VARIANTS — Among the SARS-CoV-2 strains classified by the WHO as Variants of Concern to date, bamlanivimab plus etesevimab retains activity against the Alpha (B.1.1.7) and Delta (B.1.617.2) variants and has reduced activity against the Beta (B.1.351) and Gamma (P.1) variants. Distribution of bamlanivimab and etesevimab in the US had been halted because of a relative increase in the circulation of SARS-CoV-2 variants that are resistant to the drugs.6 Since the Delta variant became predominant, however, distribution of the antibodies has resumed.7 Casirivimab plus imdevimab retains activity against all SARS-CoV-2 Variants of Concern.3

DOSAGE AND ADMINISTRATION — The authorized dosage of bamlanivimab plus etesevimab for post-exposure prophylaxis is 700 mg of bamlanivimab and 1400 mg of etesevimab given as a single IV infusion as soon as possible after exposure to SARS-CoV-2. Patients should be monitored during the infusion and for at least 1 hour after its completion. Unlike REGEN-COV, bamlanivimab and etesevimab cannot be given by subcutaneous injection. Detailed instructions on preparation and administration of the antibodies are available in the FDA Fact Sheet.2

CONCLUSION — The FDA has authorized administration of the monoclonal antibodies bamlanivimab and etesevimab together for IV post-exposure prophylaxis of COVID-19 in certain high-risk persons. In a double-blind trial in SARS-CoV-2-negative residents and staff of nursing facilities in which a confirmed infection occurred, IV infusion of bamlanivimab alone significantly decreased the risk of symptomatic COVID-19 compared to placebo. The overall effectiveness of the two antibodies together for post-exposure prophylaxis remains to be determined. Bamlanivimab plus etesevimab retains efficacy against the Delta variant of SARS-CoV-2.

REFERENCES

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