Regen-Cov: What You Need To Know

January 24th, 2022 UPDATE: The FDA has determined that REGEN-COV is not effective against the OMICRON variant. Currently, the OMICRON variant is the predominant strain causing COVID-19 infections. Consequently, the EUA has been updated to preclude the use of this medication until further notice by the FDA.

Medical product authorization- have you seen the increase press?  Since 2019, when the COVID pandemic started, there has been a spike in news about medical products being authorized for use under the FDA Emergency Use Authorizations (EUAs) mechanism. 

The EUA authority allows the FDA to grant the use of unapproved medical products in response to public health emergencies, such as the COVID-19 pandemic. These products are authorized for use and are still considered investigational. They are not officially FDA approved for any indication.

At this time, REGEN-COV® (casirivimab and imdevimab), has been authorized for the following uses against COVID-19:

Treatment:

• Mild to moderate COVID-19 in adult and pediatric patients (12 years of age and older weighing at least 40kg) with positive results of direct SARS-CoV-2 viral testing, and who are at high risk for progression to severe COVID-19, including hospitalization or death.
  • The authorized dose is 600mg of casirivimab with 600mg of imdevimab intravenous or subcutaneous as soon as possible after a positive SARS-COV-2 viral test and within 10 days of symptom onset.

Post-Exposure Prophylaxis:

• Adult and pediatric patients(12 years of age and older weighing at least 40kg) for post-exposure prophylaxis of COVID-19 in individuals who are at high risk for progression to severe COVID-19, including hospitalization or death, and:
  • Are not fully vaccinated or who are not expected to mount an adequate immune response to complete SARS-CoV-2 vaccination and 
  • Have been exposed to an individual infected with SARS-CoV-2 consistent with close contact criteria per CDC or
  • Who are at high risk of exposure to an individual infected with SARS-CoV-2 because of occurrence of SARS-CoV-2 infection in other individuals in the same institutional setting.
    • There are two dosing modalities for post-exposure prophylaxis, single dose or initial and repeat doses for individuals who will experience ongoing exposure to SARS-CoV-2 for longer than 4 weeks and who are not expected to mount an adequate immune response to complete SARS-CoV-2 vaccination:
      • Single dose: 600mg of casirivimab with 600mg of imdevimab intravenous or subcutaneous as soon as possible following exposure to SARS-CoV-2
      • Initial dose and repeat dose: 600mg of casirivimab with 600mg of imdevimab intravenous or subcutaneous followed by subsequent repeat osing of 300mg of casirivimab with 300mg of imdevimab intravenous or subcutaneous once every 4 weeks for the duration of ongoing exposure.

The FDA granted the EUA for REGEN_COV on November 21, 2020. This decision was based on review of data from phase 1 and 2 of a 1/2/3 phase, randomized, double-blind, placebo-controlled trial. Since then, data from several trials regarding the safety and efficacy have been published and form the basis for several updates to the original EUA> The overarching theme has shown that REGEN-COV reduces hospitalization or death, viral load, and severity of COVID-19 related symptoms.

On September 13, 2021, the ordering process was transitioned by the US Government from a direct order process to a state-territory-coordinated distribution system. The US Government uses weekly reports of COVID-19 cases and hospitalizations, inventory, and product usage to determine allocation amounts to the Departments of Health in each state. Consequently, facilities handling administration of REGEN-COV don not have control over the product they receive. 

There are two REGEN-COV formulations available on the market for intravenous or subcutaneous administration. There is a co-formulated product which contains both antibodies in the same vial in a 1:1 ratio of casirivimab and imdevimab or individual antibody products. Consequently, there has been some confusion with respect to the volume of drug required for dosing. To minimize confusion, we have compiled this information into one place.

Co-Formulated REGEN-COV

Casirivimab/Imdevimab 600mg/600mg per 10mL
Amount of product to use for 600mg/600mg dose = 10mL
Amount of product to use for 300mg/300mg dose= 5mL

REGEN-COV dose packs

All dose packs contain casirivimab 120mg/mL and imdevimab 120mg/mL with each medication in a separate vial with different vial combinations. Pay close attention to the vial size to determine the number of vials needed for the dose. Regardless of the vial size, the dose will be  as follows:

Casirivimab 600mg= 5mL
Imdevimab 600mg= 5mL
Total volume of medication is 10ml

or

Casirivimab 300mg= 2.5mL
Imdevimab 300mg= 2.5mL
Total volume of medication is 5 mL

References:
REGEN-COV® (casirivimab and imdevimab) Dosing. (n.d.). Retrieved November 20, 2021, from https://www.regencov.com/hcp/dosing-administration.

REGEN-COV® (casirivimab and imdevimab) Access. (n.d.). Retrieved November 20, 2021, from https://www.regencov.com/hcp/access.

“Anti-SARS-Cov-2 Monoclonal Antibodies.” National Institutes of Health, U.S. Department of Health and Human Services, www.covid19treatmentguidelines.nih.gov/therapies/anti-sars-cov-2-antibody-products/anti-sars-cov-2-monoclonal-antibodies/.

November 21, 2020 Regeneron Pharmaceuticals, inc … (n.d.). Retrieved November 20, 2021, from https://www.fda.gov/media/143891/download.

(2021) Subcutaneous REGEN-COV Antibody Combination to Prevent Covid-19. N Engl J Med 385:1184-95.

(2021) REGEN-COV Antibody Combination and Outcomes in Outpatients with Covid-19. N Engl J Med 385:e81.