Dual-antibody drugs effective against Covid-19 variants in animal study

Covid-19 therapies made from a cocktail of two types of antibodies were effective against a wide range of variants of the coronavirus in a mice and hamster study, the Washington University School of Medicine in St Louis reported on Monday.

Antibodies are used to treat cases of Covid-19, often early in the process. Former US president Donald Trump was treated with an antibody cocktail manufactured by Regeneron Pharmaceuticals in October last year after he tested positive for Covid-19.

The latest study included three of the four variants designated “variants of concern” by the World Health Organisation (WHO), including Alpha, first identified in the UK, Beta, first found in SA and Gamma found in Brazil, and an emerging variant from India similar to the Delta variant of concern.

In April the US Food and Drug Administration (FDA) revoked the emergency use authorisation of Eli Lilly’s single antibody therapy, bamlanivimab, saying there was increased circulation of variants resistant to the therapy when used alone.

Other studies have previously shown some antibody combination therapies remained potent against emerging variants of the coronavirus that were resistant to single antibody therapies.

The latest study found combinations of two antibodies often retained potency against variants even when one of the two antibodies lost some or all ability to neutralise the variant in lab studies.

The study, conducted on mice and hamsters, tested all single and combination antibody therapies authorised for emergency use by the FDA against emerging international and US variants of the virus.

The researchers evaluated the FDA-authorised combination therapies made by Regeneron, Eli Lilly and a single antibody therapy, sotrovimab, by Vir Biotechnology Inc and GlaxoSmithKline Plc.

They also assessed the antibodies in clinical trials by AbbVie Inc, Vir and AstraZeneca.

“Resistance arose with some of the monotherapies, but never with combination therapy,” wrote study co-author Jacco Boon.