(Reuters) - A federal court on Monday ruled in favor of Cubist Pharmaceuticals Inc (>> Cubist Pharmaceuticals Inc) on the interpretation of patent language in a case involving a generic challenge to its lead drug Cubicin by Hospira Inc (>> Hospira, Inc.).

The ruling, in U.S. District Court in Delaware, is a positive development for Cubist in the ongoing case, which is scheduled to go to trial in February 2014, said Cubist spokeswoman Julie DiCarlo. Cubicin, an antibiotic injection used in hospitals to treat bacterial skin infections, is the company's primary revenue driver.

"Today the court ruled in favor of Cubist on the interpretation of all disputed claim terms in our patent infringement case against Hospira," DiCarlo said.

A Hospira spokesman declined to comment, citing a company policy of not discussing ongoing litigation.

Cubist filed the patent infringement suit against Hospira in March 2012, in response to a Hospira filing with U.S. regulators indicating its intent to develop a generic version of Cubicin, DiCarlo said.

Cubist has six patents for Cubicin that expire between 2016 and 2028, she said.

Shares of Cubist, based in Lexington, Massachusetts, rose $3.97, or 8 percent, to close at $53.48 Monday on Nasdaq. Shares of Lake Forest, Illinois-based Hospira ended up 29 cents, or nearly 1 percent, at $36.03 on the New York Stock Exchange.

(Reporting by Susan Kelly in Chicago; Editing by Eric Beech)

Stocks treated in this article : Cubist Pharmaceuticals Inc, Hospira, Inc.