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Updated: Jun 22, 2025

Using Reference Reagents to Confirm Robustness of Cytokine Release Assays for the Prediction of Monoclonal Antibody Safety
Published on: September 15, 2023
Patient-Reported Outcomes in COVID-19 Treatment with Monoclonal Antibodies Reveal Benefits in Return to Usual
Diana Rofail1, Mohamed Hussein2, Ulrike Naumann3
1Regeneron Pharmaceuticals, Inc., 1 Rockwood Road, Sleepy Hollow, NY, 10591, USA. diana.rofail@regeneron.com.
Introduction:
This study aimed to assess the effects of a monoclonal antibody (mAb) combination on symptoms, daily function, and overall health-related quality of life.
Methods:
We analyzed patient-reported outcomes data from symptomatic outpatients in a phase 1/2/3 trial. Patients with confirmed SARS-CoV-2 infection and ≥ 1 risk factor for severe COVID-19 received mAb treatment (casirivimab plus imdevimab 1200 mg) or placebo. Prespecified exploratory assessments included time to sustained symptoms resolution, usual health, and return to usual activities (assessed daily for 29 days). The trial was conducted from September 2020 to February 2021, prior to widespread COVID-19 vaccination programs and Omicron-lineage variants against which casirivimab + imdevimab is not active.
Results:
In this analysis 736 outpatients received mAb and 1341 received placebo. Median time to sustained symptoms resolution was consistently shorter with mAb versus placebo (≥ 2 consecutive days: 14 vs 17 days, [nominal p = 0.0017]; ≥ 3 consecutive days: 17 vs 21 days, [nominal p = 0.0046]). Median time to sustained return to usual health and usual activities were both consistently shorter with mAb versus placebo (≥ 2 consecutive days: 12 vs 15 days [nominal p = 0.0001] and 9 vs 11 days [nominal p = 0.0001], respectively; ≥ 3 consecutive days: 14 vs 18 days [nominal p = 0.0003] and 10 vs 13 days [nominal p = 0.0041], respectively).
Conclusions:
mAb treatment against susceptible SARS-CoV-2 strains improved how patients feel and function, as evidenced by shortened time to sustained symptoms resolution and return to usual health and activities. Future studies are warranted to assess the patient experience with next generation mAbs.
Clinicaltrials:
GOV: Registration number, NCT04425629; Submission date June 11, 2020.
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