The London-listed company has agreed to pay $2.1 billion
upfront and up to $1.2 billion in potential development milestones for
Affinivax.
"GSK plc today announced that it has entered into a
definitive agreement to acquire Affinivax, Inc," it said in a statement.
"Affinivax is pioneering the development of a novel
class of vaccines, the most advanced of which are next-generation pneumococcal
vaccines," it added.
The Cambridge, Massachusetts-based firm specializes in
vaccines for diseases including meningitis, pneumonia and bloodstream
infections.
"The proposed acquisition further strengthens our
vaccines research and development (R&D) pipeline, provides access to a new,
potentially disruptive technology, and broadens GSK's existing scientific
footprint in the Boston area," said GSK's chief scientific officer Hal
Barron.
"We look forward to working with the many talented
people at Affinivax to combine our industry-leading development, manufacturing,
and commercialization capabilities to make this exciting new technology
available to those in need," added Barron, who is also the group's
president of R&D.
The acquisitions come as chief executive Emma Walmsley seeks
to reshape GSK after she faced fierce investor criticism over the company's
delay in producing COVID-19 jabs and treatments.
Glaxo last month bought US group Sierra Oncology, a
specialist in medicines for rare forms of cancer, for $1.9 billion.
GSK is meanwhile in the process of demerging its consumer
health care arm Haleon -- a joint venture with US peer Pfizer -- to concentrate
on its main pharmaceutical business.
Glaxo has been slammed by activist investors over its
failure to swiftly produce a successful COVID-19 vaccine, in stark contrast
with Anglo-Swedish rival AstraZeneca.
The Affinivax purchase is expected to complete in the third
quarter.
GSK shares climbed 0.6 percent in early Tuesday morning
deals to 1,739.07 pence on London's rising stock market.