In a hard-fought patent battle involving “groundbreaking” work by both parties, Chief Judge Stark of the U.S. District Court for the District of Delaware ruled that plaintiff Idenix’s patent for treating Hepatitis C virus (HCV) infection was invalid as a matter of law for lack of enablement. The decision overturns a $2.5 billion award to Idenix, a Merck subsidiary. The opinion provides valuable insight into the court’s thinking on enablement of method of treatment claims encompassing a large genus of therapeutic agents.

The lawsuit involved two blockbuster Gilead products for treating HCV infection, Sovaldi and Harvoni. Prior to trial, Gilead stipulated that both products infringed the asserted claims of Idenix's patent, U.S. Patent No. 7,608,597 ('597 patent), which cover a method for the treatment of HCV infection by administering an effective amount of certain nucleosides. After a two-week trial in December 2016, a jury found that Gilead failed to prove invalidity and awarded Idenix $2.5 billion in damages.

In a renewed motion for judgment as a matter of law (JMOL), Gilead urged the court to set aside the jury’s verdict on the basis of invalidity for lack of written description or non-enablement or in the alternative to reduce the jury’s damages award to $380 million lump sum payment. In an opinion granting-in-part and denying-in-part Gilead’s motion for JMOL, the court addressed each of these requests, beginning with damages and then moving on to validity.

The court denied Gilead’s motion on damages. The court found that the jury’s award of $2.5 billion based on a 10% royalty was supported by expert testimony relying on two Roche patent licenses, one with Merck (Idenix’s parent company) and the other with Pharmasset (which was acquired by Gilead). Although the court found that Gilead “leveled powerful attacks” on Idenix’s expert’s analysis, and whether the Roche licenses were “comparable” to a hypothetical license between Gilead and Idenix, the court found “they are just that: factual attacks” that the jury implicitly rejected based on substantial evidence. The court also rejected Gilead’s argument that Idenix’s expert improperly used Gilead’s entire products as a royalty base instead of a portion of those products, thereby failing to take account of Gilead’s substantial unclaimed contributions to the products. The court disagreed, holding that substantial evidence supported the jury’s implicit finding that the asserted claims cover the active ingredient in Gilead’s products and that there is no unpatented or non-infringing feature in the accused products as a result.

The court then turned to invalidity. The court disposed of Gilead’s request for a judgment of invalidity for lack of written description, pointing to its denial of Gilead’s original and renewed motions for summary judgment on this ground. As to enablement, the Court concluded that as a matter of law “no reasonable factfinder could find anything other than the ‘597 patent is not enabled.”

The court first identified structural limitations and functional limitations in the asserted claims, both of which had to be met by the nucleosides of the claims. The court noted that, at Idenix’s urging, it construed the preamble of the claim, “a method for the treatment of a hepatitis C virus infection,” to be limiting and construed its “effective amount” to require an amount effective to treat HCV. The court explained that the claims as construed therefore combine structural limitations with functional limitations.

The court found that it was undisputed that the structural limitations were literally met by an indeterminate number of compounds measured in billions and that a person of ordinary skill would be left with “likely, millions or at least many, many thousands” of compounds in attempting to practice the patent even if certain compounds were excluded based on experience and “common sense.” It was undisputed that “far fewer” compounds would also satisfy the functional limitations of the claim of being effective to treat HCV infection.

Indeed, the court noted that the patent “is replete with embodiments that are not within the scope of the claims” because they were not effective to treat HCV infection. The court explained that this evidence reflected that the patent did not disclose structural features that were sufficient for nucleosides to treat HCV infection as required by the asserted claims.

The court also held that a reasonable factfinder could only have found that the vast majority of nucleosides covered by the claims were not readily available and would have required synthesis, which takes substantial time and effort. The court found the synthesis of the compounds within the scope of the claim was complex and far from routine. It pointed to testimony recognizing that a person of ordinary skill could only make 2-3 nucleosides a month, as well as Idenix’s documented failures in trying to make the nucleoside in Gilead’s accused products.

The court further concluded that to determine which compounds meeting the structural limitations of the claims also met the functional limitations required iteratively screening the compounds for their ability to inhibit the hepatitis C virus. The court stated that unrebutted evidence demonstrated that even seemingly minor changes to effective compounds can render the compounds ineffective and that there was no simple way to readily ascertain which structures had activity. The screening for activity would take substantial time and effort on top of the time and effort required to synthesize the compounds. Given the amount of experimentation needed to refine the large number of compounds that meet the structural limitations of the claims to those that also satisfy the functional limitations, the court explained that the amount of experimentation is undue.

The court noted that its conclusion is further supported by three earlier cases invalidating claims for non-enablement: Wyeth v. Abbott, 720 F.3d 1380 (Fed. Cir. 2013) and two biotech cases, both involving patents asserted by Enzo Life Sciences, decided by Judge Stark in 2017. According to Judge Stark, just as here, in all three cases “exploring the claims’ full scope would require synthesizing and screening a significant number of candidates, time-consuming processes with unpredictable results.”