Understanding Monoclonal Antibody in Treatment of Hospitalized Patients with COVID-19

• The median age was 62 years, 54.1% were male, mean BMI was 31.1 kg/m2, 12.1% identified as Black/African American, and 30.1% identified as Hispanic/Latino.
  
• Virologic efficacy: REGEN-COV significantly reduced viral load in seronegative patients on low-flow or no supplemental oxygen; o TWA daily change in viral load from baseline through day 7: -1.03 log10 copies/mL (CI: -1.22, -0.84) in placebo vs –1.31 log10 copies/mL (CI: -1.43, -1.18) in REGEN-COV group (P=0.0172).
• Both doses of REGEN-COV exhibited similar viral load reductions, showing improvement over placebo starting at day 3 and reaching significance at day 7.
• The maximum least-squares (LS) mean differences vs. placebo in seronegative patients were at day 7 (-0.28 log10 copies/mL), day 9 (–0.47 log10 copies /mL, CI: -0.71, - 0.23), and day 11 (-0.59 log10 copies/mL CI: -0.85, -0.34).

• Death or mechanical ventilation: Treatment with REGEN-COV reduced proportion of patients who died or required mechanical ventilation, with improvement from day 1-29 in the high-viral load (RRR, 35.0%; 95% CI: 6.6%, 54.8%), seronegative (RRR, 47.0%; 95% CI: 17.7%, 65.8%), and overall (RRR, 30.9%; 95% CI, 5.4% to 49.5%) populations. The primary clinical analysis of death or mechanical ventilation from day 6-29 in patients with high-viral load had a strong positive trend but did not reach significance.
  
• All-cause mortality: Treatment with REGEN-COV led to improvement in all-cause mortality through day 29 in the seronegative, high-viral load, and overall populations. The greatest reduction in relative risk of death occurred in seronegative patients; 24/360 (6.7%) died within 28 days in the REGEN-COV group, compared to 24/160 (15.0%) in the placebo group (RRR, 55.6%; 95% CI: 24.2%, 74%).

• SAEs were experienced by more patients in the placebo group compared to the REGEN-COV group for patients on low-flow oxygen (131/469 [27.9%] placebo vs. 224/941 [23.8%] REGEN-COV) and no supplemental oxygen (43/198 [21.7%] placebo vs. 61/399 [15.3%] REGEN-COV).
  
• More patients experienced treatment-emergent adverse events that resulted in death in the placebo group compared with REGEN-COV for both patients on low-flow oxygen (72/469 [15.4%] placebo vs. 108/941 [11.5%] REGEN-COV) and no supplemental oxygen (15/198 [7.6%] placebo vs. 15/399 [3.8%] REGEN-COV).
• No safety concerns were noted overall nor in seropositive patients.

In hospitalized patients with Covid-19 on low-flow or no oxygen, REGEN-COV treatment reduced viral load and the risk of death or mechanical ventilation as well as all-cause mortality in the overall population, with the benefit-driven by seronegative patients and no harm observed in seropositive patients.