Background
The prevention of COVID-19 in vulnerable populations is a global health priority. EVADE was a phase 2/3 multicenter, double-blind, randomized, placebo-controlled trial of adintrevimab, an extended–half-life monoclonal antibody, for post-exposure (PEP) and pre-exposure prophylaxis (PrEP) of symptomatic COVID-19.
Methods
Eligible participants (vaccine-naïve, aged ≥12 years) were randomized 1:1 to receive a single 300-mg intramuscular injection of adintrevimab or placebo. Primary efficacy endpoints were reverse-transcription polymerase chain reaction (RT-PCR)-confirmed symptomatic COVID-19 through day 28 in the PEP cohort (RT-PCR-negative at baseline) and through month 3 in the PrEP cohort (RT-PCR-negative and seronegative at baseline) among participants randomized before emergence of the SARS-CoV-2 Omicron variant (30 November 2021). Safety was assessed through 6 months.
Results
Between 27 April 2021, and 11 January 2022, 2582 participants were randomized. In the primary efficacy analysis, RT-PCR-confirmed symptomatic COVID-19 occurred in 3/175 (1.7%) vs 12/176 (6.8%) adintrevimab- and placebo-treated PEP participants, respectively (74.9% relative risk reduction [RRR]; standardized risk difference –5.0%; 95% CI, –8.87 to –1.08; P=.0123), and in 12/752 (1.6%) vs 40/728 (5.5%) adintrevimab- and placebo-treated PrEP participants, respectively (71.0% RRR; standardized risk difference –3.9%; 95% CI, –5.75 to –2.01; P<.0001). In a prespecified exploratory analysis of 428 PrEP participants randomized after emergence of Omicron, adintrevimab reduced RT-PCR-confirmed symptomatic COVID-19 by 40.6% (standardized risk difference −8.4%; 95% CI, −15.35 to −1.46; nominal P=.0177) vs placebo. Adintrevimab was well tolerated with no serious drug-related adverse events reported.
Conclusions
A single intramuscular injection of adintrevimab provided prophylactic efficacy against COVID-19 due to susceptible variants without safety concerns.