Eli Lilly and Co. won a U.S. appeals court ruling that upholds the validity of a patent for the lung-cancer drug Alimta and blocks generic competition through 2017.

The U.S. Court of Appeals for the Federal Circuit on Friday rejected arguments by Teva Pharmaceutical Industries Ltd. that the patent was invalid. It affirmed a lower court ruling. The decision was posted on the court’s website.

Alimta, whose chemical name is pemetrexed, generated $2.5 billion in sales last year for Indianapolis-based Lilly, making it the company’s third biggest-selling drug. Alimta is designed to hamper cancer cells’ ability to use folic acid to grow after an initial treatment with other drugs.

Teva, based in Petah Tikva, Israel, had argued that Lilly had patented a compound that wasn’t much different from what was covered by two earlier patents. The three-judge panel said the lower court was correct to rule that the 2017 patent is distinct from the earlier inventions.

“By affirming the district court ruling, we believe that the court fairly applied long-standing patent law principles,” Lilly General Counsel Robert Armitage said in a statement. “Protection of intellectual property rights is extremely important to the biopharmaceutical industry and the physicians and patients we serve, as these rights help support the development of the next generation of innovative medicines to treat unmet medical needs.”

Denise Bradley, a spokeswoman for Teva, said the company had no comment.