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Covid-19 Antibodies Cut Viral Load, Medical Visits

SARS-Cov-2 virus

Scanning electron microscope image of SARS-Cov-2 virus, in orange, emerging from cells (NIAID, Flickr)

29 Oct. 2020. Interim results from a clinical trial show a synthetic antibody drug reduces viral burden and medical visits among non-hospitalized Covid-19 patients. The findings, which are not peer-reviewed, were released last night by biotechnology company Regeneron Pharmaceuticals Inc. from a clinical trial testing its Covid-19 therapy candidate code-named REGN-COV2.

Regeneron, in Tarrytown, New York, develops synthetic antibodies that stimulate the immune system to prevent or treat infectious diseases. The company’s VelocImmune technology produces these human antibodies with genetically engineered mice. The engineered mice become living production lines, says the company, producing antibodies that respond as a human to a specific pathogen, while not affecting the rest of the animal. The antibodies are then retrieved and combined with human genetic properties for testing as therapies.

In REGN-COV2, Regeneron uses a combination of two antibodies for neutralizing the SARS-CoV-2 virus. The company says the dual-antibody cocktail targets different parts of the infecting protein found on the surface of the coronavirus spike, which penetrates and binds to receptor proteins in cells. Regeneron says one antibody starts neutralizing the spike protein, while the second antibody blocks mutated forms of the virus that can form and escape after the initial attack.

The multi-stage clinical trial is testing REGN-COV2 among some 2,100 individuals with Covid-19 infections, but not yet hospitalized. Participants are randomly assigned to receive a high or low dose of REGN-COV2, or a placebo. The company’s study team is looking primarily for changes in viral loads, need for follow-up medical care, and reports of adverse reactions from the antibody cocktail. As reported in Science & Enterprise, Regeneron released initial interim results on 30 September showing the first 275 participants receiving REGN-COV2 experienced larger reductions in viral loads after seven days than placebo recipients, particularly those receiving the higher dose and without natural antibodies at the beginning of the trial.

The company’s new report adds findings from another 524 trial participants. In this second group, REGN-COV2 recipients with any detectable virus at the outset experience greater reductions in viral burden after seven days than placebo recipients, with the difference large enough for statistical reliability. Those reductions are even greater among recipients that began the trial with high viral loads. And as seen in the first group of results, participants without natural antibodies at the beginning of the trial gain the most benefit from REGN-COV2.

For all 799 participants reported so far, those receiving REGN-COV2 are making fewer follow-up medical visits. The results show 57 percent fewer REGN-COV2 recipients are seeking follow-up medical care than placebo recipients. And among participants at higher-risk of Covid-19 complications — older, obese, compromised immune systems, or with cardiovascular, metabolic, lung, liver, or kidney disease — REGN-COV2 recipients are making 72 percent fewer medical visits than placebo recipients.

Regeneron says differences in viral load and medical visits between high and low-dose REGN-COV2 recipients are not large enough for statistical reliability. Given these findings and the limited supply of REGN-COV2, the company is reviewing continuing the trial with two different doses. Regeneron says REGN-COV2 is generally well tolerated, with serious adverse effects reported more often among placebo than REGN-COV2 recipients. However, more infusion reactions occur among high-dose than placebo recipients.

George Yancopoulos, Regeneron’s president, says in a company statement, “Regeneron has shared these results with the U.S. Food and Drug Administration as part of its review of our Emergency Use Authorization submission, and we continue to focus on completing our ongoing trials evaluating REGN-COV2 for the treatment and prevention of Covid-19.” A companion trial is testing the antibody cocktail with hospitalized patients.

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