UK medicines regulators are reviewing emerging evidence that monoclonal antibody sotrovimab may not be as effective against the current dominant strain of Covid-19.
It comes after a decision by the US Food and Drug Administration (FDA) in early April to withdraw the authorisation for use of the drug due to an increase in the proportion of cases caused by the Omicron BA.2 sub-variant.
Data suggests that sotrovimab is unlikely to be effective against the strain, the FDA said in a statement on the 5 April.
The drug was approved for use in the UK at the end of 2021 and is given as an intravenous drip which needs to be started within the first five days of treatment. In the community, it is only available to those in several clinically vulnerable categories through Covid Medicine Delivery Units (CMDUs).
Last month, Australian researchers raised concerns about the potential for drug resistant mutations after use of sotrovimab in a small study.
Data up to the 8th April from NHS England shows it has been far the most used treatment to keep at risk people out of hospital.
So far more than 18,000 patients have received sotrovimab compared with around 6,000 doses antiviral medicines nirmatrelvir and ritonavir (Paxlovid) and just over 8,000 doses of molnupiravir (Lagevrio).
Laura Squire, chief healthcare access and quality officer at the MHRA, said that all conditional marketing authorisations, including that for sotrovimab, were under ‘constant review’ to ensure that the benefits outweighed the risks.
‘The MHRA is carefully reviewing emerging data for sotrovimab, including in response to new variants, and we continue to seek advice from the independent scientific advisory body, the Commission on Human Medicines, to determine if its benefit risk balance remains favourable,’ she added.
‘As part of this ongoing review, we are in contact with the FDA and are looking closely at the data supporting their decision. Patient safety is our top priority.’
The UK Health Security Agency is doing ongoing genomic surveillance to support the ‘rapid deployment of specific Covid-19 therapeutics’ and its next report is due on the 9th May.
Data from the latest Office for National Statistics infection survey confirms that the Omicron BA2 variant remains the most comment type of Covid-19 in the UK accounting for almost 90% of infections.