Covid: effectiveness of monoclonal antibodies challenged by variants

Published by Laurent P. · Published on 2 June 2021 at 17h00
As Covid variants keep on spreading across the world, Eli Lilly laboratories has seen their approval removed for marketing bamlanivimab, as a monotherapy, being a therapy based on monoclonal antibodies. Why? Its effectiveness challenged by new coronavirus strains. Keep reading to find out more!

Monoclonal antibodies, a promising Covid therapy challenged by variants? This is what seems to happen with the increase in new coronavirus strains, more contagious, and diverting the effectiveness of therapies currently given, and research.

A constatation sparking many worries, so much that this past late May, bamlanivimab – therapy designed by Eli Lilly laboratory based on monoclonal antibodies, approved in the U.S. since November 2020 and used in hospitals to soften severe Covid – has seen its approval for monotherapy use removed. Why? Its reduced and even void use because of the different variants spreading worldwide.

A lack of effectiveness noticed by several studies, including the last one recently carried out on the Indian variant by Institut Pasteur, European Georges Pompidou hospital, Orléans regional hospital, and StrasbourgUniversity Hospital, concluding this therapy does not work against this strain.

A study echoing to another – led by the University of Columbia – reading that 18 monoclonal antibodies – whether studied or already given in hospitals – have seen their effectiveness reduced because of the UK variant. Among these 18 antibodies studied, four of them were even void against the South African and Brazilian variants.

But everything is not lost since three more antibody therapy – namely etesevimab (Eli Lilly), casirivimab (Regeneron) and imdevimab (Regeneron) – are still working – on a lesser basis – against this strain. Another effective solution: mixing products, such as triple therapies to fight against HIV. Eli Lilly – to overcome the effectiveness issue – has mixed bamlanivimab to etesevimab, reducing – all strains included – by 87% the risk of evolution of the disease towards a more sever form than it already is.

As for Regeneron, this strategy is the one used since the beginning of trials on the matter. A strategy now used in many countries as for the administration of these therapies. For instance, this is the case in the U.S. or in France where the ANSM gave the green light for using two antibodies cocktails: casirivimab/imdevimab by Regeneron – commercialized by the Roche laboratories in Europe – and bamlanivimab/etesevimab by Eli Lilly.

Last solution also considered: scanning antibodies banks and finding new ones working against the variants. A genuine race against time against these new strains threatening progresses made so far. The fight must go on anyway to overcome this pandemic.

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