Safety and Pharmacokinetics of Repeat Dosing of Long-Acting SARS-CoV-2 Antibodies Tixagevimab/Cilgavimab (AZD7442): Results from the PROVENT Sub-study

BACKGROUND AND OBJECTIVES: The PROVENT study demonstrated the efficacy and safety of a single 300-mg dose of AZD7442 (tixagevimab/cilgavimab) for pre-exposure prophylaxis of COVID-19 in at-risk individuals. Here we report an analysis of repeat dosing of intramuscular AZD7442 300 and 600 mg from the PROVENT sub-study. METHODS: The sub-study enrolled eligible participants from the parent study, creating four sub-study groups. Group 1 received AZD7442 300 mg in PROVENT followed by one 300-mg dose in the sub-study (10-14 months apart). Group 2 received placebo in PROVENT followed by two AZD7442 300-mg doses 6 months apart in the sub-study. Group 3a received AZD7442 300 mg in PROVENT followed by one 300-mg dose and two 600-mg doses 6 months apart in the sub-study. Group 3b received placebo in PROVENT followed by one 300-mg dose and two 600-mg doses 6 months apart in the sub-study. The primary endpoint was safety. Secondary endpoints included pharmacokinetics and anti-drug antibody (ADA) responses. RESULTS: Adverse events (AEs) and serious AEs (SAEs) were reported in 75.7-81.5% and 13.2-16.8% of participants, respectively. AZD7442-related AEs, SAEs, and AEs of special interest occurred in 1.4-5.3%, 0-0.2%, and 0-5.3% of participants, respectively, and 3.9-6.7% experienced ≥ 1 cardiac and/or thromboembolic SAE. AZD7442 serum concentrations were dose-dependent with minimal accumulation following redosing, and 4.1-10.7% had treatment-emergent ADAs to AZD7442. CONCLUSIONS: AZD7442 safety, pharmacokinetic, and ADA response profiles were similar regardless of repeat dosing schedule, and consistent with single-dose study data. These results may support future use of long-acting antibodies. GOV REGISTRATION: NCT04625725.