January 23, 2022

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Antibody cocktail REGEN-COV significantly improve the survival rate!

Antibody cocktail REGEN-COV significantly improve the survival rate of hospitalized COVID-19 patients who lack immune response


Antibody cocktail REGEN-COV significantly improve the survival rate!  Recently, Regeneron announced the positive results of UK RECOVERY, the largest clinical trial evaluating monoclonal antibodies in hospitalized patients with severe COVID-19.

Data show that in patients who fail to develop a natural antibody response against the new coronavirus (SARS-CoV-2), compared with conventional care, antibody cocktail therapy REGEN-COV (casirivimab and imdevimab) combined with conventional care reduces the risk of death 20%.

REGEN-COV is a cocktail therapy consisting of two kinds of antibodies, which are directed against two independent and non-overlapping sites in the SARS-CoV-2 spike protein receptor binding region. They have a synergistic effect and can reduce The risk of virus mutation and escape, and protect the population from virus variants with mutations in the spike protein. REGEN-COV can prevent SARS-CoV-2 infection and treat infection by accelerating virus clearance.

Peter Horby, co-chief investigator of the RECOVERY trial and Professor of Emerging Infectious Diseases at the Nuffield School of Medicine, Oxford University, said: “These results are very exciting. We hope to reduce the worst manifestations of COVID-19 through antibody cocktail therapy. There is great uncertainty about the value of viral therapy in advanced COVID-19 disease. We are pleased to learn that even in advanced COVID-19 disease, targeted virus therapy can reduce those that do not produce an antibody response. The patient’s mortality rate.”

David Weinreich, Executive Vice President of Global Clinical Development of Regeneron, said: “The RECOVERY trial showed that in patients who did not self-produce SARS-CoV-2 antibodies, treatment with the REGEN-CoV antibody cocktail can significantly reduce the risk of death or use of ventilator. The length of hospital stay in the hospital has been shortened. This trial was conducted when most patients had not been fully vaccinated (September 18, 2020-May 22, 2021). These results are for those who have been exposed to vaccines or natural infections. Patients with poor immune responses and those who have been exposed to variants of the virus but whose existing antibodies may not work well provide hope.”

REGEN-COV was developed to treat and prevent COVID-19 infection. In August 2020, Roche and Regeneron reached a strategic cooperation to develop, manufacture and distribute REGEN-COV to all parts of the world. The drug will provide a much-needed treatment option for those infected with COVID-19 symptoms, and has the potential to be Prevent infection in high-risk populations who have been exposed to the virus, thereby slowing the spread of the global pandemic.

In the United States, the FDA has granted REGEN-COV Emergency Use Authorization (EUA) for the treatment of high-risk populations who have recently been diagnosed with mild to moderate COVID-19, specifically: new coronavirus (SARS-CoV-2) direct detection method Children and adults with a positive result and a high risk of developing severe COVID-19 and/or hospitalization, age ≥ 12 years, and weight ≥ 40 kg. The recently announced Phase 3 trial showed that REGEN-COV can reduce the risk of hospitalization or death in high-risk non-hospital patients by 70%.


RECOVERY is the first trial large enough to determine whether REGEN-COV can reduce mortality in hospitalized patients with severe COVID-19. Previous Phase 3 trials in non-hospitalized COVID-19 patients showed that REGEN-COV reduced the virus level, shortened the time to symptom relief, and significantly reduced the risk of hospitalization or death. In a phase 1/2 trial of hospitalized patients, REGEN-COV also rapidly reduced the level of the virus. Preliminary evidence shows that it reduces the risk of death or mechanical ventilation. The benefits are naturally derived from those who did not enter the trial on their own. Driven by patients with antibody reactions (serologically negative); in the absence of REGEN-COV treatment, the mortality of serologically negative patients is higher than that of patients who have developed an autoimmune reaction (serologically positive).

Based on the above Phase 1/2 data, the independently run RECOVERY trial prospectively focuses on seronegative patients. Similar to the previous trial, in the case of receiving only routine care, the mortality rate on day 28 was twice that of serologically negative patients (30%) than serologically positive patients (15%). In the RECOVERY trial, approximately one-third of the hospitalized patients were serologically negative (n=3153), half of the patients were serologically positive (n=5272), and one-sixth of the patients had an unknown serological status (n=1360) . The average age of the patients being compared was 62 years, and more than 90% of all groups received corticosteroid therapy.

The main results of the RECOVERY trial showed that the addition of REGEN-COV 8000 mg treatment to routine care reduced the all-cause mortality of seronegative patients (main analysis population) by 20% (death on day 28) Rate: 24% in the REGEN-COV group and 30% in the routine care group; odds ratio [RR]=0.80; 95%CI: 0.70-0.91; p=0.001). When the larger seropositive group (and the group with unknown status) is combined with seronegative patients, the 28-day mortality rate no longer has a significant impact (the total mortality rate in the REGEN-COV group is 20%, and the routine care group 21%; RR=0.96; 95%CI: 0.86-1.03; p=0.17).

Among seronegative patients in the RECOVERY trial, the median length of hospital stay in the REGEN-COV group was shortened by 4 days (13 days vs. 17 days), and the proportion of patients who survived and discharged by day 28 was higher (64% vs 58%; RR=1.19; 95%CI: 1.08-1.30). Among seronegative patients who did not use invasive mechanical ventilation at baseline, the composite endpoint risk of progression to invasive mechanical ventilation or death in the REGEN-COV group was lower than that in the conventional care group (30% vs 37%; RR=0.83; 95 %CI: 0.75-0.92). No such benefit was found in the entire trial population (combined serologically negative, positive, or patients with unknown status).

Multiple analyses, including those recently published in the academic journal Cell, have shown that REGEN-COV retains its effectiveness against major virus variants circulating in the United States; therefore, REGEN-COV can still be used in all 50 states use. REGEN-COV pairs include P.1 (first discovered in Brazil, now classified as gamma [Gamma, γ] by the World Health Organization (WHO)), B.1.351 (first discovered in South Africa, now classified by WHO as Beta [Beta] , Β]) and B.1.162.2 (first discovered in India, now classified as Delta [Delta, δ] by the WHO) virus variants remain effective. Currently, in 8 U.S. states (Arizona, California, Florida, Illinois, Indiana, Massachusetts, Oregon, Washington), the combined frequency of P.1 and B.1.351 variants exceeds that of newly diagnosed COVID -19 cases in 10%, the prevalence of these and other variants is still under close monitoring.


(source:internet, reference only)

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