Gilead Sciences Inc said an arbitration panel rejected Roche Holding AG's patent infringement claims related to Gilead's hepatitis C drug, Sovaldi.
Gilead's shares rose as much as 3 percent in early trading.
"While this outcome was widely expected, it is good nonetheless as it removes a 'disaster scenario'," Cowen & Co analyst Phil Nadeau said, raising his price target to $105 from $95.
Roche initiated arbitration proceedings against Gilead in 2013, asserting exclusive rights over sofosbuvir by virtue of its 2004 collaboration agreement with Pharmasset Inc. Gilead bought Pharmasset in 2012.
Gilead started selling sofosbuvir under the brand name Sovaldi in December.
The arbitration panel on Thursday determined that Roche failed to establish any of its claims and is not entitled to any damages or other relief, Gilead said in a regulatory filing on Friday.
Sovaldi, which costs $84,000 for 12 weeks of treatment, had sales of $3.5 billion in the second quarter ended June.
The cost of Sovaldi, which cures well in excess of 90 percent of patients in as little as 8 weeks of treatment, has drawn sharp criticism from insurers and government officials.
Gilead's shares were up 1 pct at $97.70 in late morning trading on the Nasdaq. Up to Thursday's close, the stock had risen 28 percent this year.
(Reporting by Shailesh Kuber; Editing by Sriraj Kalluvila)