Study: Antibody Reduces Death in COVID-19 Patients Unable to Mount an Immune Response

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Regeneron's COVID-19 antibody cocktail REGEN-COV continues to demonstrate efficacy against the coronavirus. Data from a new British study shows REGEN-COV reduced the risk of death in hospitalized patients unable to mount their own immune response by 20%.

This was the first trial to demonstrate that the antibody treatment improved survival in patients hospitalized with COVID-19. The company said it would share the data from the study with regulatory agencies and request that the Emergency Use Authorization granted in the United States be extended to include appropriate hospitalized patients. 

REGEN-COV, a combination of two monoclonal antibodies, casirivimab and imedvimab, was first granted EUA in November 2020. Earlier this month, the FDA greenlit a lower dose version of the medication.

Study data showed that adding REGEN-COV to the standard of care in these hospitalized patients reduced the risk of death by 20% in the immune-inactive patients compared to standard of care alone. By 28 days, the study showed that 24% of patients in the REGEN-COV group died versus 30% in the usual care group. 

Among the patients considered seronegative who took part in the RECOVERY trial, the median duration of hospital stay was four days shorter in the REGEN-COV group. The proportion of patients who were discharged by day 28 was significantly higher at 64%. 

Among the seronegative patients not on invasive mechanical ventilation at baseline, the risk of progressing to the composite endpoint of invasive mechanical ventilation or death was lower among the REGEN-COV group than the usual care group, 30% compared to 37%, respectively.

Regeneron noted there was no longer a significant effect on 28-day mortality when data from the seronegative and seropositive patients were combined. Overall, 20% of patients in the REGEN-COV group died, compared to 21% in the usual care group, the company said. 

David Weinreich, executive vice president of Global Clinical Development at Regeneron, said the RECOVERY study showed that treating patients unable to make their own COVID-19 antibodies with REGENE-COV “dramatically reduced their risk of dying or being on a ventilator.” Weinreich added that REGEN-COV shortened the number of days these patients remained in the hospital. 

“The trial was conducted at a time when most patients had not been fully vaccinated. These results provide hope to patients who have a poor immune response to either the vaccine or natural infection, as well as those who are exposed to variants for whom their existing antibodies might be sub-optimal,” Weinreich said. 

The RECOVERY study in the U.K. is the first large trial that has definitively shown that REGEN-COV reduces mortality in patients hospitalized with severe COVID-19. In a previous Phase I/II study in hospitalized patients, REGEN-COV demonstrated efficacy at reducing viral levels in patients unable to mount an immune defense. 

Preliminary evidence from that study suggested the antibody cocktail could lower the risk of death or the chances a patient would be moved to mechanical ventilation. In addition, studies conducted prior to RECOVERY have shown the efficacy of REGEN-COV in non-hospitalized COVID-19 patients.

Sir Peter Horby, Professor of Emerging Infectious Diseases at the University of Oxford and Joint Chief Investigator for the RECOVERY trial, called the results of the study exciting. 

“The hope was that by giving a combination of antibodies targeting the SARS-CoV-2 virus, we would be able to reduce the worst manifestations of COVID-19. There was, however, great uncertainty about the value of antiviral therapies in late-stage COVID-19 disease. It is wonderful to learn that even in advanced COVID-19 disease, targeting the virus can reduce mortality in patients who have failed to mount an antibody response of their own,” Horby said in a statement. 

Regeneron Chief Scientific Officer George D. Yancopoulos said definitive data from multiple Phase III studies have shown that REGEN-COV can alter the course of COVID-19 infection, from early to late stages. He thanked the RECOVERY team for their ongoing work assessing the antibody in patients. Yancopoulos said the trial results mean even more patients could benefit from REGEN-COV.

“We intend to rapidly discuss these results with regulatory authorities, including in the U.S. where we will ask for our EUA to be expanded to include appropriate hospitalized patients,” he said. 

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