An antibody cocktail developed by Regeneron Pharmaceuticals Inc. has received emergency use authorization (EUA) from the FDA for the treatment of mild to moderate COVID-19. Monoclonal antibodies (Mabs) such as Regeneron's, called casirivimab and imdevimab, "have the greatest benefit when given early after diagnosis and in patients who have not yet mounted their own immune response or who have high viral load," the company said.

The flipside of that was captured in the FDA's announcement, which noted that MAbs "may be associated with worse clinical outcomes when administered to hospitalized patients with COVID-19 requiring high flow oxygen or mechanical ventilation." Accordingly, the EUA excludes that group.

The EUA, granted Nov. 21, arrived shortly after a similar authorization for Eli Lilly and Co.’s second COVID-19 antibody, bamlanivimab. Like bamlanivimab, there is no mortality benefit in the label for Regeneron's therapy, said SVB Leerink analyst Geoffrey Porges. Instead, the basis of the Regeneron EUA was the reduction in viral load, COVID-19 hospitalization or emergency department visits in the 28 days after treatment in COVID-19-positive individuals.

The data supporting the EUA for casirivimab and imdevimab are based on a randomized, double-blind, placebo-controlled clinical trial in 799 non-hospitalized adults with mild to moderate COVID-19 symptoms. Of those patients, 266 received a single I.V. infusion of 2,400 mg casirivimab and imdevimab, 267 received an 8,000-mg dose of the cocktail, and 266 received a placebo, within three days of obtaining a positive SARS-CoV-2 viral test.

For patients at high risk for disease progression, hospitalizations and emergency room visits occurred in 3% of casirivimab and imdevimab-treated patients on average compared to 9% in placebo-treated patients, the FDA said. Both adults and children, 12 or older weighing about 88 pounds or more, at high risk for progressing to severe disease are eligible for the treatment.

Initial doses of the therapy, formerly known as REGN-COV2, will be made available to about 300,000 patients, with no out-of-pocket costs, under a U.S. government allocation program, Tarrytown, N.Y.-based Regeneron said. Instead, U.S. taxpayers at large will foot the bill, through a $450 million federal manufacturing and supply contract awarded to Regeneron in July as part of the U.S. government's Operation Warp Speed.

Regeneron is working with Roche Holding AG, of Basel, Switzerland, which in August agreed to help develop, manufacture and distribute the antibody cocktail. Each company committed to dedicate a certain amount of manufacturing capacity to the therapy each year, with Regeneron distributing it and recording sales in the U.S. and Roche responsible for distribution outside the U.S.

Shares of Regeneron (NASDAQ:REGN) rose 1% to $523.61 on Nov. 23.

NO go (for now)

Separately Monday, Bellerophon Therapeutics Inc. put a clinical hold on a phase III test of its inhaled nitric oxide technology, Inopulse, sending company shares down (NASDAQ:BLPH) 17.8% to close Nov. 23 at $7.22.

Warren, N.J.-based Bellerophon said an independent data monitoring committee had completed its prespecified interim analysis from the first 100 patients randomized in the trial, called COViNOX. The interim analysis, as requested by the FDA, was limited to the evaluation of safety and a single efficacy endpoint of respiratory failure or death (RFD), the company said. To date, the company has recruited close to 200 patients, of which 100 were included in the interim analysis.

"Of note, the interim analysis included 10 RFD events, representing a small sample size for evaluation of the RFD endpoint," said Bellerophon CEO Fabian Tenenbaum. "We intend to complete the study procedures for the remaining patients and evaluate the full dataset, which will include additional clinically important endpoints, such as change in clinical status and duration of hospitalization, in order to assess potential next steps in our COVID-19 program," he said.

Nitric oxide has been tested by several other companies for the treatment of COVID-19, such as Morrisville, N.C.-based Novan Inc., which on Oct. 30 said it planned to move toward testing its Nitricil platform against SARS-CoV-2 in preclinical IND-enabling studies.