UPDATE 3-GSK says tests indicate antibody drug works against Omicron

* Sotrovimab, developed with Vir, tested in lab and on
hamsters

* Key Omicron mutations did not elude drug activity in study

* Tests continuing on further mutations
(Adds methods, chief scientist's comment)

By Ludwig Burger

Dec 2 (Reuters) - Laboratory analysis of the antibody-based
COVID-19 therapy GlaxoSmithKline (GSK) is developing
with U.S. partner Vir has indicated the drug is
effective against the new Omicron variant, the British drugmaker
said on Thursday.

A GSK statement said that lab tests and a study on hamsters
have demonstrated the sotrovimab antibody cocktail works against
viruses that were bio-engineered to carry a number of hallmark
mutations of the Omicron variant.

The two companies have been engineering so-called
pseudoviruses that feature major coronavirus mutations across
all suspicious variants that have emerged so far, and have run
lab tests on their vulnerability to sotrovimab treatment.

An analysis of past tests has now yielded the preliminary
clearance for the drug, because Omicron' main mutations have
been found across a variety of previous variants.

"We've been carefully following every mutation that might be
important," said Herbert Virgin, Vir's Chief Scientific Officer.

"With this new variant, the mutations that we have tested so
far have no significant effect on sotrovimab," he added.

Importantly, the mutations within the area on the spike
protein that the sotrovimab antibodies bind to did not make a
difference.

For confirmation, a pseudovirus with all of the Omicron
mutations is now being tested, with an update expected by the
end of the year, GSK added in its statement.

The antibody is designed to latch on to the spike protein on
the surface of the coronavirus, but Omicron has been found to
have an unusually high number of mutations on that protein.

“Sotrovimab was deliberately designed with a mutating virus
in mind," said Vir Chief Executive George Scangos, adding that
the drug was targeting a region of the spike protein that was
highly unlikely to mutate.

Separately, Britain's drug regulator on Thursday approved
sotrovimab, also known under the brand name Xevudy, for people
with mild to moderate COVID-19 and who are at high risk of
developing severe disease.

The Medicines and Healthcare products Regulatory Agency
(MHRA) recommended use of Xevudy as soon as possible and within
five days of the onset of symptoms.

Sotrovimab is based on monoclonal antibodies, which are
lab-made versions of natural antibodies the body generates to
fight off infection. Similar products are offered or being
developed by Eli Lilly, Regeneron and
AstraZeneca.

Regeneron on Tuesday said that lab tests and computer
modelling suggest that COVID-19 antibody drugs including
Regeneron's would have reduced efficacy against the Omicron
variant.
(Reporting by Ludwig Burger; Editing by David Goodman and Jan
Harvey)