Synairgen plc announced topline data for participants treated with SNG001 in the US National Institutes of Health (NIH)/AIDS Clinical Trials Group (ACTG)-led ACTIV-2 Phase 2 adaptive platform trial for COVID-19. Between February and August 2021, 221 symptomatic, non-hospitalised adult participants with COVID-19 were enrolled in the Phase 2 SNG001 evaluation and randomised between active drug (N=110 treated) and placebo (N=110 treated[1]), across 25 US sites. There were no statistically significant differences between SNG001 and placebo with respect to the primary outcomes of safety (SNG001 was well-tolerated), symptom resolution, or virology.

Fewer participants required hospitalisation following treatment with SNG001 (N=1/110, [1%]) compared to placebo (N=7/110, [6%]),an 86% relative risk reduction, that was not statistically significant (P=0.07; two-sided Fisher's exact test). There were no deaths in either arm. There were 13 participants with treatment-emergent Grade 3 or higher Adverse Events (AE) with four on SNG001 [3.6%] and nine on placebo [8.2%].

Based on the study results, the Independent Data Safety Monitoring Board for ACTIV-2 recommended SNG001 advance from Phase 2 into Phase 3 in the ACTIV-2 trial in October 2021. Later, in March 2022, the NIH decided to halt all participant recruitment in the trial due to the significant shift in the nature of the pandemic which would necessitate a substantial modification of the study design which was not feasible in a multiple treatment-arm platform trial of this size.