GP-681

This study aimed to evaluate the therapeutic effect of suraxavir marboxil (GP681, abbreviated as suraxavir) in adults with uncomplicated influenza.

We conducted a multi-centre randomized, double-blind, placebo-controlled phase 2 trial in 18 Chinese centres. Participants had to be aged 18 to 65 years with a positive influenza test, presenting with at least one influenza systemic and respiratory symptom in at least moderate severity within 48 hours of onset. Participants were randomly assigned in 1:1:1 to receive suraxavir 40 mg, 20 mg or placebo once. The primary outcome was defined as the time to alleviation of influenza symptoms (from treatment to normal body temperature and resolution of all 7 influenza symptoms for ≥21.5 hours) within 15 days. Our trial was registered at clinicaltrials.gov (NCT04736758).

From 8 January 2021 to 18 December 2021, 245 participants were randomly assigned, and 203 (82.9%) were included in the intention-to-treat infected population, with median age of 29.0 (interquartile range: 11.0 years) years and the most common virus of influenza B (99.5%, 202/203). The median time to alleviation of influenza symptoms was shorter in 2 suraxavir groups (40 mg: 50.0 [44.1-71.9] hours; 20 mg: 46.1 [39.6-58.2] hours) than placebo group (82.3 [67.9-87.3] hours). The mean (±SD) changes in viral titres from baseline in the suraxavir 40 mg group, suraxavir 20 mg group, and placebo group were -2.14 ± 1.97, -1.48 ± 2.01, and -0.69 ± 1.98 log₁₀ 50% tissue culture infectious dose/mL by 1 day after administration, respectively. The incidences of adverse events were similar in each group (47.2%, 34/72; 46.6%, 34/73; 53.5%, 38/71). The most reported adverse event was diarrhoea (7.6%, 11/145). Only one serious adverse event of pulmonary infection occurred in the placebo group. No I38T polymerase acidic protein variants were detected.

In this trial, timely single-dose suraxavir was effective in improving clinical symptoms and accelerating viral clearance in adults with uncomplicated influenza B infection and demostrated good safety.