Safety and Efficacy of SAB-185 for Nonhospitalized Adults With COVID-19: A Randomized Clinical Trial

Abstract

Background: We evaluated the fully human polyclonal antibody product SAB-185 in a phase 3 trial for COVID-19.

Methods: Nonhospitalized high-risk adults within 7 days of symptom onset were randomized 1:1 to open-label SAB-185 3840 units/kg or casirivimab/imdevimab 1200 mg. Noninferiority comparison was undertaken for pre-Omicron population (casirivimab/imdevimab expected to be fully active) and superiority comparison for the Omicron population (casirivimab/imdevimab not expected to be active). Primary outcomes were the composite of all-cause hospitalizations/deaths and grade ≥3 treatment-emergent adverse events (TEAEs) through day 28. A secondary outcome was time to sustained symptom resolution.

Results: Enrollment ended early due to low hospitalization/death rates upon Omicron emergence; 255 adults were in pre-Omicron and 392 in Omicron populations. Hospitalizations/deaths occurred in 6 (5.0%) and 3 (2.2%) of pre-Omicron SAB-185 and casirivimab/imdevimab arms (absolute difference 2.7%; 95% confidence interval [CI], -2.3%-8.6%); and 5 (2.5%) versus 3 (1.5%) (absolute difference 1.0%; 95% CI, -2.3%-4.5%) for Omicron. All risk ratios for grade ≥3 TEAEs were not significant. Time to symptom resolution was significantly shorter for SAB-185 for Omicron only: 18 versus >25 days; P =.006.

Conclusions: SAB-185 had an acceptable safety profile with faster symptom resolution in the Omicron population.

Clinical trials registration: NCT04518410.

Keywords: COVID-19; SAB-185; casirivimab/imdevimab; outpatient treatment; transchromosomic.