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Regen-CoV for preventing the further spread of COVID-19

Regen-CoV is the brand name of a combination of two antibodies that attack SARS-CoV-2. The antibodies are as follows:

  • casirivimab
  • imdevimab

Regeneron Pharmaceuticals, the developer of the antibodies, has conducted a placebo-controlled study in 409 adults without COVID-19 who were living with someone who had been diagnosed with COVID-19. The purpose of the study was to find out if Regen-CoV could reduce the risk of the virus infecting other people in the household.

The antibodies were given via injection just under the skin (subcutaneous injection) at a dose of 600 mg each (for a combined total dose of 1,200 mg) within 96 hours of a household member testing positive by PCR (polymerase chain reaction) for SARS-CoV-2. Participants had nasal swabs done at the start of the study and weekly to collect samples for SARS-CoV-2 testing.

The average profile of participants at the start of the study was as follows:

  • age – mid-50s
  • 54% women, 46% men
  • major ethno-racial groups – 78% white, 50% Hispanic, 13% Black, 3% Asian (due to the overlap of ethno-racial categories, the total proportion does not equal 100%)
  • body mass index (BMI) – 29

Results

The distribution of initially negative household contacts with a subsequent positive test for SARS-CoV-2 was as follows:

  • placebo – 10%
  • Regen-CoV – 5%

Among people who tested positive for SARS-CoV-2, the duration of infection was generally shorter for those who received Regen-CoV vs. placebo. Also, people who received Regen-CoV subsequently had significantly less SARS-CoV-2 in their blood than people on placebo.

Side effects

Monitoring skin reactions at the site of injection is important in studies of injectable medicines. The distribution of injection site reactions in this study was as follows:

  • Regen-CoV – 3%
  • placebo – 1%

The proportions of participants with at least one serious adverse event were as follows:

  • placebo – 1%
  • Regen-CoV- 1%

Details were not provided on the serious adverse events. No hypersensitive reactions or seizures occurred.

—Sean R. Hosein

REFERENCE:

  1. O’Brien MP, Forleo Neto E, Chen K-C, et al. Casirivimab with imdevimab antibody cocktail for COVID-19 prevention: Interim results. In: Program and abstracts of the Conference on Retroviruses and Opportunistic Infections, 6–10 March 2021. Abstract 123.
  2. Baum A, Ajithdoss D, Copin R, et al. Regen-COV2 antibodies prevent and treat SARS-CoV-2 infection in rhesus macaques and hamsters. Science. 2020 Nov 27;370(6520):1110-1115.
  3. Baum A, Fulton BO, Wloga E, et al. Antibody cocktail to SARS-CoV-2 spike protein prevents rapid mutational escape seen with individual antibodies. Science. 2020 Aug 21;369(6506):1014-1018.