Combination of Casirivimab, Imdevimab Provides Long-Term Protection Against COVID-19

A single 1200 mg subcutaneous dose of casirivimab and imdevimab (Regen-COV, Regeneron Pharmaceuticals), a preventative COVID-19 treatment, reduced the risk of contracting COVID-19 by 81.6% during months 2-8, according to additional results from a phase 3 trial published in The New England Journal of Medicine.

“These results demonstrate that Regen-COV has the potential to provide long-lasting immunity from SARS-CoV-2 infection, a result particularly important to those who do not respond to COVID-19 vaccines including people who are immunocompromised,” said Myron S. Cohen, MD, director of the Institute for Global Health & Infectious Diseases at the University of North Carolina at Chapel Hill, in a press release.

Previously published results demonstrated the trial met its primary endpoint, reducing the risk of COVID-19 by 81.4% within 1 month of receiving Regen-COV. These new data are from a pre-specified analysis for the following 7 months, during which the drug continued to prevent infection without requiring additional doses.

“In this trial, a single dose of Regen-COV provided long-term protection against COVID-19, including times of particularly high risk from household exposure, and in the longer-term during ongoing broader exposure,” said George D. Yancopoulos, MD, PhD, president and chief scientific officer at Regeneron, in the release. “These data add to the increasing body of evidence supporting use of Regen-COV to prevent COVID-19 in uninfected individuals, which may be especially useful for the many immunocompromised people who do not respond adequately to vaccines and remain 'prisoners of the pandemic.' With infections still occurring despite widespread vaccination, the immunocompromised face an ongoing risk of encountering the virus during their daily lives. We intend to rapidly share these additional data with regulatory authorities to help those in most need of protection from COVID-19.”

Compared to placebo, patients who received a single dose of Regen-COV had an 81.6% reduced risk of developing COVID-19 during the pre-specified follow-up period and an 81.5% reduced risk of developing COVID-19 at any time during the 8 months after receiving their single dose, according to the study. Further, during the 8-month assessment period, no participants in the Regen-COV arm were hospitalized due to COVID-19, compared to 6 patients in the placebo arm. No deaths from COVID-19 were reported in either arm and no new safety signals were identified for Regen-COV.

Regen-COV is currently authorized in the United States to treat individuals who are at high risk of serious consequences from COVID-19 infection who are either already infected but not hospitalized or in certain post-exposure prophylaxis settings.

REFERENCE

New phase 3 analyses show that a single dose of Regen-COV® (casirivimab and imdevimab) provides long-term protection against COVID-19 [news release]. Regeneron; November 8, 2021. Accessed November 8, 2021. https://investor.regeneron.com/news-releases/news-release-details/new-phase-3-analyses-show-single-dose-regen-covr-casirivimab-and