Tixagevimab/Cilgavimab Im and Iv for Covid-19: A Randomized Controlled Activ-2 Trial

ABSTRACT

Background: Within the ACTIV-2/A5401 platform (NCT04518410), the safety and efficacy of tixagevimab/cilgavimab (T/C), an anti-SARS-CoV-2 monoclonal antibody combination, was studied in outpatients with COVID-19. Intravenous (IV) and intramuscular (IM) administration of T/C were assessed. Method(s) Non-hospitalized adults >=18 years enrolled within 10 days of positive SARS-CoV-2 test and symptom onset. Participants at higher risk of disease progression were eligible for IV T/C 300mg (150mg each component) or placebo;all were eligible for IM T/C 600mg (300mg each) administered to the lateral thigh or placebo. Co-primary outcomes were time to symptom improvement through day 28;nasopharyngeal (NP) SARS-CoV-2 RNA below lower limit of quantification (LLoQ) on days 3, 7 or 14;and treatment emergent Grade >=3 adverse events. Result(s) Between February and May 2021, 223 participants (106 T/C, 117 placebo) initiated study intervention and were included in the IM analysis and 114 participants (58 T/C, 56 placebo) in the IV analysis;the IV study was stopped early for administrative reasons. Both studies enrolled 45% Latinx;the IM and IV populations included 12% and 19% Black participants, 49% and 59% female sex at birth, and median age was 39 and 44 years, respectively, all of which were balanced between active vs placebo for each. Median (IQR) days from symptom onset at enrollment was 6 (4, 7). There were no differences in time to symptom improvement comparing IM T/C to placebo (median 8 (IQR 7, 12) vs 10 (8, 13) days;p=0.35) or IV T/C to placebo (11 (9, 15) vs 10 (7, 15) days;p=0.71). A significantly greater proportion (80%) in the IM T/C arm had NP SARS-CoV-2 RNA below LLoQ at day 7 compared to placebo (65%), but not days 3 or 14, overall p=0.003 across visits. Secondary and post-hoc analyses revealed antiviral effects within the smaller IV study. There was no difference in Grade >=3 AEs with either administration route. Fewer participants were hospitalized who received T/C vs placebo (4 vs 7 in IM group;0 vs 4 in IV group), neither group reaching statistical significance. Conclusion(s) Tixagevimab/cilgavimab administered IM or IV was well-tolerated and demonstrated antiviral activity and a trend towards fewer hospitalizations, but did not change time to symptom improvement in mild-to-moderate COVID-19 compared to placebo. Monoclonal antibodies administered intramuscularly to the thigh may present a valuable alternative for early SARSCoV-2 infection. Virologic Outcomes of Tixagevimab/Cilgavimab treatment 600mg IM (panels A and B) or 300mg IV (panels C and D) versus placebo.