A Randomized Placebo-Controlled Trial of Leronlimab in Mild-To-Moderate COVID-19

Purpose: Early in the course of the SARS-CoV-2 pandemic it was hypothesised that host genetics played a role in the pathophysiology of COVID-19 including a suggestion that the CCR5-Δ32 mutation may be protective in SARS-CoV-2 infection. Leronlimab is an investigational CCR5-specific humanized IgG4 monoclonal antibody currently in development for HIV-1 infection. We aimed to explore the impact of leronlimab on the severity of disease symptoms among participants with mild-to-moderate COVID-19.

Methods: The TEMPEST trial was a randomized, double-blind, placebo-controlled study in participants with mild-to-moderate COVID-19. Participants were randomly assigned in a 2:1 ratio to receive subcutaneous leronlimab (700 mg) or placebo on days 0 and 7. The primary efficacy endpoint was assessed by change in total symptom score based on fever, myalgia, dyspnea, and cough, at end of treatment (day 14).

Findings: Overall, 84 participants were randomized and treated with leronlimab (n = 56) or placebo (n = 28). No difference was observed in change in total symptom score (P = 0.8184) or other pre-specified secondary endpoints between treatments. However, in a post hoc analysis, 50.0% of participants treated with leronlimab demonstrated improvements from baseline in National Early Warning Score 2 (NEWS2) at day 14, compared with 20·8% of participants in the placebo group (post hoc; p = 0.0223). Among participants in this trial with mild-to-moderate COVID-19 adverse events rates were numerically but not statistically significantly lower in leronlimab participants (33.9%) compared with placebo participants (50.0%).

Implications: At the time the TEMPEST trial was designed although CCR5 was known to be implicated in COVID-19 disease severity the exact pathophysiology of SARS-CoV-2 infection was poorly understood. Today it is well accepted that SARS-CoV-2 infection in asymptomatic-to-mild cases is primarily characterized by viral replication, with a heightened immune response, accompanied by diminished viral replication in moderate-to-severe disease and a peak in inflammatory responses with excessive production of pro-inflammatory cytokines in critical disease. It is therefore perhaps not surprising that no differences between treatments were observed in the primary endpoint or in pre-specified secondary endpoints among participants with mild-to-moderate COVID-19. However, the results of the exploratory post hoc analysis showing that participants in the leronlimab group had greater improvement in NEWS2 assessment compared to placebo provided a suggestion that leronlimab may be associated with a lower likelihood of people with mild-to-moderate COVID-19 progressing to more severe disease and needs to be confirmed in other appropriately designed clinical trials.

Clinicaltrials: gov number, NCT04343651 https://classic.

Clinicaltrials: gov/ct2/show/NCT04343651.