ZURICH (Reuters) – Swiss drugmaker Roche is paying up to $1.4 billion to buy U.S. biotech company Promedior, whose main drug candidate against the lung disease idiopathic pulmonary fibrosis is set to begin late-stage trials, Promedior said on Friday.

The deal includes a payment of $390 million, plus the potential for $1 billion more if conditions are met. Promedior’s lead asset PRM-151 is being studied in IPF where the firm said it helped improve lung function, on top of current therapies.

Roche already has an IPF medicine, Esbriet, with 2018 sales of just over $1 billion.

(The story fixes typo in third paragraph.)

(Reporting by John Miller; Editing by Michael Shields)