Regeneron Pharmaceuticals, Inc. announced October 28th, 2020 positive, prospective results from an ongoing Phase 2/3 seamless trial in the COVID-19 outpatient setting showing its investigational antibody cocktail, REGN-COV2, met the primary and key secondary endpoints. REGN-COV2 significantly reduced viral load and patient medical visits (hospitalizations, emergency room, urgent care visits and/or physician office/telemedicine visits).
“The first job of an antiviral therapeutic drug is to lower the viral load, and our initial data in 275 patients strongly suggested that the REGN-COV2 antibody cocktail could lower viral load and thereby potentially improve clinical outcomes. Today’s analysis, involving more than 500 additional patients, prospectively confirms that REGN-COV2 can indeed significantly reduce viral load and further shows that these viral reductions are associated with a significant decrease in the need for further medical attention,” said George D. Yancopoulos, M.D., Ph.D., President and Chief Scientific Officer of Regeneron. “We continue to see the strongest effects in patients who are most at risk for poor outcomes due to high viral load, ineffective antibody immune response at baseline, or pre-existing risk factors. 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.”
The randomized, double-blind trial is measuring the effect of adding REGN-COV2 to usual standard-of-care, compared to adding placebo to standard-of-care. A descriptive analysis from the first 275 patients was previously reported. Today’s data, involving an additional 524 patients, show the trial met all of the first nine endpoints in the statistical hierarchy, which assessed virologic endpoints based on viral load, seronegative status and dose group, as well as the key clinical endpoint of COVID-19 related medically-attended visits, in patients who had laboratory-confirmed COVID-19 at baseline. 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.
Virologic results (n=524, prospectively confirming previous 275-patient analysis):
- On the primary endpoint, the average daily change in viral load through day 7 (mean time-weighted average change from baseline) in patients with high viral load (defined as greater than107 copies/mL) was a 0.68 log10 copies/mL greater reduction with REGN-COV2 compared to placebo (combined dose groups; p<0.0001). There was a 1.08 log greater reduction with REGN-COV2 treatment by day 5, which corresponds to REGN-COV2 patients having, on average, a greater than 10-fold reduction in viral load, compared to placebo.
- In the overall patient group with detectable virus at baseline, the average daily reduction in viral load through day 7 was a 0.36 log10 copies/mL greater reduction with REGN-COV2 compared to placebo (combined dose groups; p=0.0003).
- As in the earlier analysis, patients with higher viral load at baseline and/or no detectable antibodies at baseline (suggesting their bodies had not yet mounted an effective immune response), derived greater benefit from REGN-COV2 therapy.
Clinical results in the overall population (n=799):
- On the key clinical endpoint, treatment with REGN-COV2 reduced COVID-19 related medical visits by 57% through day 29 (2.8% combined dose groups; 6.5% placebo; p=0.024).
- Treatment with REGN-COV2 reduced COVID-19 related medical visits by 72% in patients with one or more risk factor (including being over 50 years of age; body mass index greater than 30; cardiovascular, metabolic, lung, liver or kidney disease; or immunocompromised status) (combined dose groups; nominal p = 0.0065).
There was no planned formal statistical analysis of symptom alleviation in this analysis; descriptive analyses did not reveal robust associations with viral load, serology status or treatment. REGN-COV2 was well tolerated in the trial. 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).
“We will submit detailed results from this trial for publication in order to share insights with the public health and medical communities,” said David Weinreich, M.D., Senior Vice President and Head of Global Clinical Development at Regeneron. “We would like to thank the global investigators, sites and patients who continue to work with us to conduct REGN-COV2 trials across different settings and geographies.”
Additional Trial Background
In the overall patient population (n=799), patients were prospectively characterized prior to treatment by serology tests to see if they had already generated antiviral antibodies on their own and were thus classified as seronegative (no measurable antiviral antibodies) or seropositive (measurable antiviral antibodies). Approximately 38% of patients were seropositive, 51% were seronegative and 11% were categorized as “other” due to unclear or unknown serology status. Approximately 50% of patients were Hispanic, 9% were African American and 60.5% had one or more underlying risk factors for severe COVID-19, including obesity (37%). On average, patients were 42.2 years of age. In total, 47% of participants were male and 53% were female.
The Phase 3 portion of this trial continues in non-hospitalized patients. REGN-COV2 is also being studied in a Phase 2/3 clinical trial for the treatment of COVID-19 in hospitalized patients, the Phase 3 open-label RECOVERY trial of hospitalized patients in the UK and a Phase 3 trial for the prevention of COVID-19 in household contacts of infected individuals.