April 3 (Reuters) - British pharmaceutical giant

GlaxoSmithKline and rival Pfizer ( PFE ) have agreed to

end a lawsuit that alleged Pfizer's ( PFE ) respiratory syncytial virus

(RSV) vaccine Abrysvo violated GSK's patent rights in its

competing RSV shot Arexvy, according to a Thursday filing in

Delaware federal court.

GSK and Pfizer ( PFE ) said in the filing that they would dismiss

the case with prejudice, which means it cannot be refiled.

Spokespeople for the companies did not immediately respond to

requests for comment and more information, including whether the

case was settled.

GSK, Pfizer ( PFE ) and Moderna ( MRNA ) have developed RSV shots

approved by the U.S. Food and Drug Administration, with GSK's

Arexvy responsible for the majority of U.S. RSV vaccine sales.

The respiratory disease typically causes cold-like symptoms, but

it is also a leading cause of pneumonia in toddlers and older

adults.

GSK sued Pfizer ( PFE ) in 2023, arguing that the New York-based

company's vaccine infringed GSK patents related to antigen

technology. GSK said in the lawsuit that Pfizer ( PFE ) began working on

its RSV program around 2013, at least seven years after GSK

began developing its shot.

Pfizer ( PFE ) denied the allegations and argued GSK's patents were

invalid. It convinced a London court to invalidate related UK

patents owned by GSK in a separate case last year.

GSK has also sued Pfizer ( PFE ) for patent infringement in the U.S.

over technology in Pfizer's ( PFE ) blockbuster COVID-19 vaccine

Comirnaty. That case is still ongoing.