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Regeneron reports results of its “antibody cocktail” treatment for COVID-19: news release

EM of SARS-COV-2 from Groopman lab

Regeneron has published a news release on October 28, 2020 giving results of its ongoing Phase 2/3 trial of its “antibody cocktail” treatment for COVID-19, showing a greater than ten-fold reduction in viral load and:

“Treatment with REGN-COV2 reduced COVID-19 related medical visits by 72% in patients with one or more risk factor.”

This treatment, called REGN-COV2, is the one touted by our current president after he spent three days in hospital with COVID-19 at the beginning of October. It appears to be highly successful and to have a low incidence of side effects.

From the news release:

Results showed no significant difference in virologic or clinical efficacy between the REGN-COV2 high dose (8 grams) and low dose (2.4 grams). Based on this finding, Regeneron is reviewing potential changes to dosing in the ongoing outpatient clinical trial given the current limited supply of REGN-COV2…

Serious adverse events were numerically more frequent with placebo than REGN-COV2 treatment (0.8% high dose, 1.6% low dose; 2.3% placebo). Numerically more infusion reactions occurred with the REGN-COV2 high dose compared to placebo (1.5% high dose; 0% low dose; 0.4% placebo)…

REGN-COV2 is a combination of two monoclonal antibodies (REGN10933 and REGN10987) and was designed specifically to block infectivity of SARS-CoV-2, the virus that causes COVID-19.

To develop REGN-COV2, Regeneron scientists evaluated thousands of fully-human antibodies produced by the company’s VelocImmune® mice, which have been genetically modified to have a human immune system, as well as antibodies identified from humans who have recovered from COVID-19. The two potent, virus-neutralizing antibodies that form REGN-COV2 bind non-competitively to the critical receptor binding domain of the virus’s spike protein, which diminishes the ability of mutant viruses to escape treatment and protects against spike variants that have arisen in the human population, as detailed in Science.

This monoclonal antibody treatment appears very promising, but unfortunately it is in highly limited supply. Only some 50,000 treatment courses are currently available, less than the daily number of new cases appearing in the US presently. Large quantities of this antibody are unlikely to become available in the future.

Since it is most effective when given early in the course of infection, we are left with the dilemma of choosing to whom it should be given. It is difficult or impossible to predict at the outset which patients will be most affected by the disease, so prioritizing treatment to the sickest will not be possible. Most likely, the treatment will be given to those who can pay the most or who are considered the most valuable to society– not an equitable strategy.

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