GSK/Vir: antibody booster can work wonders

For all the success of Covid-19 vaccines, the need for life-saving treatments remains. Monoclonal antibodies, a class of drugs that mimic the body’s natural defences, are among the best hopes. On Thursday, the UK’s GSK and Vir Biotech of the US announced impressive trial results for their candidate: an 85 per cent reduction in hospitalisation or death.

This goes some way to vindicate GSK’s decision to back the San Francisco-based biotech. It invested $250m last April because it was impressed by Vir’s approach. Vir screens patients for unusually potent antibodies that are then synthesised and mass produced.

Peak sales for the GSK/Vir treatment could be as much as $3.5bn, Barclays estimates. It will not make much difference to GSK, entitled to only 27.5 per cent of the profits from the treatment. But it could be a reputational boost. One of the world’s biggest vaccine makers has been an also-ran when it came to developing a Covid-19 jab.

The stakes, though, are high for Vir. Its shares, favoured by short sellers, shot up by 23 per cent when the market opened. That nearly wipes out losses last week when hopes dimmed that the drug would help patients who have already been hospitalised.

Much is still left to prove. The treatment is a relative latecomer. Regeneron’s antibody treatment — hailed as a “miracle” by President Trump — was authorised by the FDA in November. Eli Lilly has also received the green light for its antibody cocktail, shown to be highly effective by additional trial data released this week.

The market for antibody treatments — estimated by Evaluate to be more than $4bn this year — is a fraction of that for Covid-19 vaccines. The economics are very different: antibody manufacturers are selling millions, rather than billions of doses, at prices that can be a hundred times higher. Even so, it will be a cost-effective treatment for high-risk patients. GSK and Vir have a chance to create a blockbuster.

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