GlaxoSmithKline (GSK) and Vir Biotechnology have reported that the intramuscular (IM) dose of its experimental therapy, sotrovimab, met the primary goal of the Phase III COMET-TAIL clinical trial in at-risk patients with mild-to-moderate Covid-19.

A SARS-CoV-2 neutralising monoclonal antibody, sotrovimab attaches to an epitope on the virus.

The multicentre, randomised, open-label trial analysed the safety, efficacy and tolerability of IM doses of sotrovimab against intravenous (IV) doses as an early intervention in at-risk, non-hospitalised individuals aged 12 years and above.

It enrolled 983 subjects up to seven days after the symptom development.

Findings showed that the IM doses of sotrovimab were non-inferior to IV doses, meeting the primary goal. In the high-risk group, the efficacy of IM doses of the antibody treatment was comparable to IV doses.

Through Day 29, a 2.7% rate of progression to hospital admission for more than 24 hours or mortality was observed in the IM sotrovimab arm versus 1.3% in the IV arm.

Low rates of adverse events of Grade 3-4 and serious nature were also reported in both arms.

Vir Biotechnology CEO George Scangos said: “This trial was conducted during the height of circulation of the Delta variant, with significant enrollment in Florida – a hot spot for this particular variant and where hospitalisation rates averaged more than 10% of confirmed cases.

“We designed sotrovimab to stand up to the variants that we anticipated would occur, and these data demonstrate that sotrovimab administered via IV or IM could prove important in the fight against Covid-19 following authorisation.”

GSK and Vir intend to seek regulatory approvals from various agencies worldwide while the companies are holding talks with the US Food and Drug Administration on the current Emergency Use Authorization for sotrovimab.

In June 2021, the companies announced positive results from the Phase III COMET-ICE trial of sotrovimab in high-risk adult patients with mild-to-moderate Covid-19 in the outpatient setting.