Regeneron (REGN 0.84%) has moved up a few paces in the COVID-19 drug-development race. The company announced after market hours on Tuesday that its REGN-COV2 candidate has shown positive results in clinical trials.

In the first results published from the phase 1/2/3 study, Regeneron said that in the first 275 trial patients, REGN-COV2 "reduced viral load and the time to alleviate symptoms in non-hospitalized patients with COVID-19."

Those patients were all afflicted with mild to moderate COVID-19, the disease caused by the SARS-CoV-2 coronavirus. Two different REGN-COV2 doses were administered to two distinct patient populations -- one seropositive (able to produce an immune response on their own) and the other seronegative (unable to do so adequately).

Significant side effects were only apparent in two patients, Regeneron said, and those individuals were taking placebos.

Gloved and masked medical researchers using microscopes in their work.

Image source: Getty Images.

Regeneron's candidate is a "cocktail" of two antibodies (substances produced by the body's immune system to attack a certain illness). The company launched its clinical trials of the candidate in June, investigating its efficacy as both a preventive medication and a treatment for COVID-19.

The company is preparing to bring REGN-COV2 to market if it is successful with later stages of the trials and if the drug is approved for use. It has already signed a supply agreement with the U.S. government worth $450 million.

"We are highly encouraged by the robust and consistent nature of these initial data, as well as the emerging well-tolerated safety profile, and we have begun discussing our findings with regulatory authorities while continuing our ongoing trials," the company quoted its Chief Scientific Officer George Yancopoulos as saying.

Despite the encouraging news, Regeneron shares were trading down by nearly 2.4% in late afternoon trading on Wednesday in contrast to the gains of the wider stock market.