GILD Gilead Sciences Inc

Gilead Sciences Inc. (GILD) agreed to acquire privately held Arresto Biosciences Inc., a biotechnology drug developer that focuses on treatments for fibrotic diseases and cancer, for $225 million plus possible milestone payments.

The deal comes as a host of drug makers have been making licensing pacts with and acquisitions of drug developers in hopes of bolstering their pipelines.

Gilead has dominated the market for HIV treatment and receives royalties from Roche Holding AG (ROG.VX, RHHBY) for Tamiflu, which Gilead discovered. But it has cut revenue expectations twice this year due to impacts from currency fluctuations and potential impacts of the U.S. health-care overhaul.

Gilead shares closed Friday at $37.19 and were inactive premarket.

-By Tess Stynes, Dow Jones Newswires; 212-416-2481; Tess.Stynes@dowjones.com;