MARSHALL, Texas—A federal judge here on Monday ruled that four Allergan patents related to the dry eye treatment Restasis are invalid. The patents at issue recently had been transferred to the Saint Regis Mohawk Tribe in an unusual arrangement that drew criticism of Allergan in Washington, as VMail reported.

In a statement Monday, Allergan said it will appeal the district court’s ruling.

U.S. Circuit Judge William C. Bryson of the Eastern District of Texas issued the ruling. In his decision, he wrote, “The court therefore holds that while Allergan has proved by a preponderance of the evidence that the defendants have infringed the asserted claims of the Restasis patents, the defendants have proved by clear and convincing evidence that the asserted claims of the Restasis patents are invalid for obviousness.”

In its statement, Allergan said it was “disappointed by the federal District Court's decision on the Restasis patents.” Allergan chief legal officer Robert D. Bailey in the statement added: “We are carefully reviewing the decision and are considering all options. Allergan remains committed to vigorously defending the intellectual property of our products, which allows us to continue to invest in developing and bringing forward new medicines for millions of patients.”

Allergan also noted that “to date” none of the proposed generic versions of Restasis has received regulatory approval and “none of these products would be able to launch in the market.”

In September, as VMail reported, Allergan assigned all six of its Restasis patents to the Saint Regis Mohawk Tribe and received an exclusive license to the patents from the Native American tribe. According to observers in Washington, the move by Allergan was a way to protect itself from a patent challenge—distinct from this patent challenge in district court in Texas—under an administrative process at the U.S. Patent and Trademark Office.

The Mohawk tribe has claimed that sovereign immunity shields the patents from challenges under that process.

The defendants in the litigation included the generic drug manufacturers Teva Pharmaceuticals USA, Akorn and Mylan, which contended that the patent claims asserted by Allergan are invalid, according to the court documents. However, the FDA has not approved a generic version of Restasis, meaning a generic of the $1.5 billion Restasis is not likely to be marketed for several years.

The patents at issue, along with two others that relate to Restasis, are listed in the Orange Book and expire on Aug. 27, 2024, according to Dublin-based Allergan.