Swiss pharmaceuticals giant Novartis has announced job cuts at its Horsham site in West Sussex.
A company spokesman said Novartis planned to reduce the total workforce of 950 at the site by 550.
The move comes as a further blow to the UK's pharmaceutical research and development (R&D) industry.
In February, Pfizer said would close its research and development facility at Sandwich in Kent, which employs 2,400 people.
Of the 950 employees on the Horsham campus approximately 330 are dedicated to respiratory research.
"With significant changes in healthcare systems aimed to contain or cut cost, this critical assessment and the subsequent potential changes to the Novartis UK organisation are key to maintain significant investment in innovative drugs and our research efforts in the UK," said Sue Webb, general manager at Novartis, in a statement.
The drugs industry in general is scaling back investment in R&D, despite the need to find new medicines as the patents on older drugs expire.
The Novartis and Pfizer plans will be implemented over the next two years.