IDENIX PHARMACEUTICALS LLC v. GILEAD SCIENCES INC.

Before Prost, Newman, and Wallach. Appeal from the United States District Court for the District of Delaware.

Summary: Synthesizing and screening tens of thousands of compounds to identify those within the scope of the claims was undue experimentation that rendered claims invalid for lack of enablement.

Idenix Pharmaceuticals and Universita Degli Studi Di Cagliari (collectively, “Idenix”) sued Gilead Sciences, Inc. for patent infringement, alleging that Gilead’s sofosbuvir drug product would infringe Idenix’s patent claims directed to methods of treating hepatitis C virus (HCV). At the district court, Gilead argued that the claims are invalid under § 112 for failure to meet the written description and enablement requirements. The jury upheld the validity of the patent, and Gilead filed a motion for JMOL on both grounds, which the district court granted only with respect to enablement.

In a split decision, the Federal Circuit affirmed the invalidity of the claims for lack of enablement and reversed the denial of JMOL for lack of written description. Under the district court’s claim construction, which no party challenged on appeal, the patent covers methods of administering nucleoside compounds with a particular structure (a methyl group at the 2' up position) and function (efficacy in treating HCV). The majority concluded that the claims are invalid for lack of enablement because billions of compounds meet the structural limitation, and a skilled artisan would not be able to identify the small subset that are also effective to treat HCV without synthesizing and screening at least tens of thousands of those compounds. The majority emphasized that, even accepting Idenix’s contention that synthesis and screening of a single compound were routine, the degree of experimentation required to practice the full scope of the invention rendered the claims invalid.

The majority also held that the claims are invalid for lack of written description support. The specification discloses four examples of compounds with demonstrated efficacy against HCV and lists other potentially effective compounds. The majority concluded that this disclosure is not sufficient to show possession of the full claim scope because the specification provides no meaningful guidance for identifying undisclosed compounds that meet the claim limitations. The majority placed significant emphasis on the fact that the compound in Gilead’s accused product is not included among the thousands of disclosed compounds.

In dissent, Judge Newman argued that the Federal Circuit should have adopted a claim construction narrower than the one adopted by the district court, and under that narrower construction Judge Newman would have upheld the validity of the patent claims under § 112.