Regeneron Pharmaceuticals said Tuesday that adding REGN-COV2 to standard-of-care reduced viral load as well as the time to symptom alleviation in non-hospitalized patients with COVID-19. The company noted that first data from an ongoing adaptive phase 1/2/3 trial of its investigational dual antibody cocktail also showed “positive trends” in reducing medical visits. Regeneron indicated that it plans “rapidly” to discuss these results with regulatory authorities.
“The greatest treatment benefit was in patients who had not mounted their own effective immune response, suggesting that REGN-COV2 could provide a therapeutic substitute for the naturally occurring immune response,” remarked chief scientific officer George Yancopoulos. “These patients were less likely to clear the virus on their own, and were at greater risk for prolonged symptoms,” he added.
The “descriptive” analysis included the first 275 patients enrolled in the trial who were randomised to receive one of two doses of REGN-COV2, via a one-time infusion, or placebo. All participants were being treated in the outpatient setting for laboratory-confirmed COVID-19. Patients were characterised prior to treatment by serology tests to see if they had already generated antiviral antibodies on their own, with about 45% being seropositive, 41% seronegative and 14% classified as “other” because of unclear or unknown serology status.
Regeneron said that REGN-COV2 “rapidly reduced” viral load through day seven in seronegative patients, noting that this was a key virologic endpoint. Specifically, in the seronegative group, patients treated with high-dose REGN-COV2 had a mean reduction in nasopharyngeal viral load that was 0.60 log10 copies/mL greater than placebo, while those given the low dose had a 0.51 log10 copies/mL greater reduction than placebo. In the overall population, Regeneron said there was a 0.51 log10 copies/mL greater reduction in patients treated with the high dose, and a 0.23 log10 copies/mL greater reduction in patients given the low dose, compared to placebo.
Greater benefit with higher viral load
In addition, patients with higher baseline viral levels had correspondingly greater decreases in viral load after one week with REGN-COV2 treatment. This ranged from reductions of roughly 50% to 60% for those with viral loads higher than 105 copies/mL, all the way to reductions of approximately 99% for those with more than 107 copies/mL.
The company also said that patients who were seronegative and/or had higher baseline levels of virus also appeared to derive more benefit from REGN-COV2 in terms of symptom alleviation, which was defined as symptoms becoming mild or absent. Among seronegative patients, median time to symptom improvement was 13 days for placebo, compared to eight days for those on high-dose REGN-COV2, and six days for patients in the low-dose group. Meanwhile, seropositive patients in the placebo group saw their symptoms ease after a median seven days.
In terms of safety, Regeneron said both doses were well-tolerated, with serious adverse events occurring in two placebo patients, one low-dose patient and no high-dose patients. There were no deaths in the trial.
Regeneron said the trial is part of a larger program that also includes studies of REGN-COV2 for the treatment of hospitalized patients, as well as for prevention of infection in people who have been exposed to COVID-19 patients. Last month, the company struck a deal with Roche to boost production capacity for REGN-COV2.
Other companies working on antibody-based treatments for COVID-19 include GlaxoSmithKline and Vir Biotechnology, which recently launched the phase 2/3 COMET-ICE trial to test VIR-7831 for the early treatment of COVID-19 in patients at high risk of progressing to severe disease. An initial data readout for that study could come before the end of the year. Meanwhile, Eli Lilly earlier this month reported interim findings for its SARS-CoV-2 neutralizing antibody LY-CoV555 in mild-to-moderate recently diagnosed COVID-19 patients.