Regeneron Announces Preliminary Clinical Results of REGN-COV2 Antibody Cocktail Showing Greater Efficacy in Patients with Inadequate Immune Response

Regeneron Announces Preliminary Descriptive Data from Its Investigational COVID-19 Neutralizing Antibody Cocktail Therapy, REGN-COV2, in a Seamless Phase 1/2/3 Clinical Trial. The data show that REGN-COV2 reduces viral load and shortens the time to symptom resolution in non-hospitalized patients with COVID-19. REGN-COV2 also demonstrated a positive trend in reducing hospital visits among patients.

REGN-COV2 is a combination antibody therapy consisting of two monoclonal antibodies that target distinct epitopes on the spike protein of SARS-CoV-2. It is designed to bind to the viral spike protein, thereby preventing SARS-CoV-2 from entering and infecting cells, which alleviates symptoms of COVID-19. The data announced today were derived from 275 non-hospitalized patients with COVID-19. All participants had confirmed SARS-CoV-2 infection via nucleic acid testing. Prior to treatment, they underwent serological testing and viral load measurement. The results showed that approximately 45% of patients were seropositive, 41% were seronegative, and 14% were categorized as “other” due to indeterminate or unknown serological status.

Patients were randomized in a 1:1:1 ratio to receive a single dose of high-dose REGN-COV2 (8 mg), low-dose REGN-COV2 (2.4 mg), or placebo.

The main findings of the study include:

Baseline serological status was highly correlated with baseline viral load (p<0.0001).

Serology-positive patients had significantly lower baseline viral levels, with viral loads rapidly declining to the lowest quantifiable limit even without treatment. In contrast, serology-negative patients had significantly higher baseline viral levels and cleared the virus more slowly in the absence of treatment.

Baseline serological status can also predict the rate of resolution of clinical symptoms in patients with COVID-19.

Among patients receiving placebo treatment, the median time to symptom relief was 7 days for serology-positive patients, compared with 13 days for serology-negative patients.

REGN-COV2 Demonstrates Superior Efficacy in Seronegative Patients

In seronegative patients, the mean reduction in viral load was 0.60 log10 copies/mL (p=0.03) in the high-dose treatment group compared with the placebo group. The corresponding value in the low-dose treatment group was 0.51 log10 copies/mL (p=0.06). In the overall population, viral load reductions were 0.51 log10 copies/mL in the high-dose treatment group and 0.23 log10 copies/mL in the low-dose treatment group, compared with placebo.

Meanwhile, REGN-COV2 shortened the time to symptom resolution in seronegative patients; the median times to symptom resolution were 13 days, 8 days, and 6 days in the placebo, high-dose, and low-dose groups, respectively.

Higher Baseline Viral Load Is Associated with Greater Efficacy of REGN-COV2

Patients with higher baseline viral levels exhibited a greater reduction in viral load after 7 days of treatment with REGN-COV2.

· In patients with a viral load greater than 10⁵ copies/mL, the viral load was reduced by approximately 50–60% compared with placebo.

· In patients with a viral load higher than 10E6 copies/mL, the viral load was reduced by approximately 95% compared to placebo.

· In patients with viral loads higher than 10E7 copies/mL, viral load was reduced by approximately 99% compared to placebo.

Dr. George D. Yancopoulos, President and Chief Scientific Officer of Regeneron, stated, “We are very encouraged to see that the antibody cocktail therapy REGN-COV2 rapidly reduces viral load and associated symptoms in patients with COVID-19, with the greatest benefit observed in those who have not mounted an effective endogenous immune response. This suggests that REGN-COV2 can serve as a therapeutic alternative to naturally occurring immune responses. These initial data are highly encouraging, and we have already begun discussions with regulatory authorities regarding our findings while continuing our ongoing clinical trials. In addition to their positive implications for the REGN-COV2 clinical program and other antibody therapies, these data also support the promise of vaccines targeting the SARS-CoV-2 spike protein.”

References:

[1] REGENERON'S REGN-COV2 ANTIBODY COCKTAIL REDUCED VIRAL LEVELS AND IMPROVED SYMPTOMS IN NON-HOSPITALIZED COVID-19 PATIENTS. Retrieved September 29, 2020, from https://investor.regeneron.com/news-releases/news-release-details/regenerons-regn-cov2-antibody-cocktail-reduced-viral-levels-and

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