Allergan Holdings Unlimited Co. v. MSN Labs. Private Ltd.

Case Name: Allergan Holdings Unlimited Co. v. MSN Labs. Private Ltd., Civ. No. 23-794-RGA, 2024 WL 3444368 (D. Del. July 17, 2024) (Andrews, J.) 

Drug Product and Patent(s)-in-Suit: Viberzi® (eluxadoline); U.S. Patent No. 11,484,527 (“the ’527 patent”)

Nature of the Case and Issue(s) Presented: The ’527 patent belongs to a patent family covering various inventions related to eluxadoline and claims priority to an application that issued as U.S. Patent No. 9,675,587 (“the ’587 patent”). From a continuation of the same patent application, Plaintiffs also obtained U.S. Patent No. 10,188,632 (“the ’632 patent”). Plaintiffs sued Sun in 2019, asserting the ’587 and ’632 patents, after Sun filed an ANDA seeking approval to market generic eluxadoline (“the 19-1727 litigation”). Over the course of the case, Plaintiffs eventually asserted eight patents during the 19-1727 litigation. The application leading to the ’527 patent was filed on December 8, 2021. The ’527 patent issued on November 1, 2022, and covers methods of treatment by administering eluxadoline.

On July 21, 2023, Plaintiffs asserted the ’527 patent against Sun, which action has since been consolidated into the present case along with Plaintiffs’ actions against MSN. On January 19, 2024, Sun filed its Amended Answer asserting a counterclaim of prosecution laches (Count III counterclaim), an affirmative defense of unenforceability based on prosecution laches and/or unclean hands (Seventh Affirmative Defense), and an affirmative defense of patent misuse (Eighth Affirmative Defense). Plaintiffs moved to dismiss those counterclaims and defenses, and the court agreed.

Why Allergan Prevailed: Count III Counterclaim. Sun alleged that it was prejudiced as a result of Plaintiffs’ delay in prosecuting the ’527 patent. Specifically, Sun alleged that it faced prejudice from the delay because it “invested time and resources seeking to commercialize generic versions of Plaintiffs’ Viberzi® brand eluxadoline tablets” and “because Allergan’s delay has unnecessarily resulted in increased costs and duplicative litigation.” The ’527 patent does not claim the eluxadoline tablet; instead, it claims a method of treatment involving the eluxadoline tablet. Therefore, Sun’s claims that it invested time and resources into commercializing the tablets is not equivalent to allegations that it invested in, worked on, or used the claimed technology. Moreover, increased litigation costs are also insufficient to demonstrate prejudice. In this case, there was no subversion of the Hatch-Waxman Act by extended litigation because Sun is precluded from launching its generic product until July 7, 2028, in any event.

Seventh Affirmative Defense. This affirmative defense raises the issues of prosecution laches and unclean hands. The prosecution laches defense fails for the same reason as the Count III Counterclaim. Sun alleged that “Allergan is fully aware that the ’527 patent and the similar patents being prosecuted are invalid and should never have been issued by the U.S. Patent and Trademark Office” but still sought “to enforce these patents—to harass Sun as part of an egregious case of misuse of the statutory patent system.” Specifically, Sun stated, “Despite representing to the Patent Office that ‘the only way to truly understand how food will affect the pharmacokinetic and pharmacodynamics of a drug is to conduct a food effect study,’ the inventors never conducted a food effect study on eluxadoline.” Plaintiffs’ unclean hands defense theory, in substance, is based on inequitable conduct before the PTO. As Sun’s affirmative defense sounds in fraud, it must satisfy the heightened Rule 9(b) pleading standard, which it did not.

Eighth Affirmative Defense. Sun’s patent misuse defense theory relies on the same factual allegations as its unclean hands defense. Thus, because Sun failed to comply with the Rule 9(b) pleading requirements, the court stuck Sun’s eighth affirmative defense.