CHARACTERIZATION OF SINGLE VERSUS DUAL ACTIVE mAB AGAINST SARS-CoV-2

ABSTRACT

Background: Amubarvimab and romlusevimab are anti-SARS-CoV-2 monoclonal antibodies (mAbs) that significantly reduced the risk of hospitalizations or death in the ACTIV-2/A5401 trial. SARS-CoV-2 variants (e.g., Delta, Epsilon, Lambda) harbor mutations against romlusevimab. We evaluated viral kinetics and resistance emergence in individuals treated with mono versus dual-active mAbs. Method(s) The study population included 789 non-hospitalized participants at high risk of progression to severe COVID-19 enrolled in the ACTIV-2/ A5401 platform trial (NCT04518410) and received either placebo (n=400) or amubarvimab plus romlusevimab (n=389). Anterior nasal (AN) swabs were collected for SARS-CoV-2 RNA testing on days 0-14, and 28. Spike (S) gene nextgeneration sequencing were performed on samples collected at study entry and the last sample with viral load >=2 log10 SARS-CoV-2 RNA copies per ml. We compared viral load kinetics and resistance emergence with single versus dual-active mAbs by categorizing participants as harboring variants sensitive to amubarvimab alone (Delta, Epsilon, Lambda, Mu) versus those sensitive to both mAbs (Alpha, Beta, Gamma, Others). Result(s) Study participants receiving single and dual-active mAbs had similar demographics, baseline AN viral load, baseline symptom score and duration since symptom onset. The most common SARS-CoV-2 variant in the study population was Delta (26%) followed by Gamma (19%), Alpha (12%), and Epsilon (10%). In those with successful sequencing, 37% (N=111) were infected with a variant sensitive to amubarvimab alone and 63% (N=188) were infected with a variant sensitive to both mAbs. Compared to treatment with a singleactive mAb, treatment with dual-active mAbs led to faster viral load decline at study day 3 (p=0.0001) and day 7 (p=0.003). Treatment-emergent resistance mutations were significantly more likely to be detected after amubarvimab plus romlusevimab treatment than placebo (2.6% vs 0%, P=0.0008). mAb resistance was also more frequently detected in the setting of single-active mAb treatment compared to dual-active mAb treatment (7.2% vs 1.1%, p=0.007). Participants with emerging mAb resistance had significantly higher pretreatment SARS-CoV-2 nasal viral RNA levels. Conclusion(s) Compared to single-active mAb therapy, dual-active mAb therapy led to significantly faster viral load decline and lower risk of emerging mAb resistance. Combination mAb therapy should be prioritized for the next generation of mAb therapeutics.