District of Delaware Finds Allergan Patents Invalid for Lack of Written Description and Obviousness-Type Double Patenting in Allergan v. MSN Labs


On September 27, 2023, Judge Richard Andrews, following a three-day bench trial, determined that several patents asserted by Allergan against Sun Pharmaceuticals and MSN Laboratories were invalid for lack of written description under 35 U.S.C. § 112. Allergan USA, Inc. v. MSN Lab’ys Priv. Ltd., No. CV 19-1727-RGA, 2023 WL 6295496, *11, *19, *21 (D. Del. Sept. 27, 2023). Further, Judge Andrews found that an additional patent asserted by Allergan was invalid for obviousness-type double patenting. Id. at *22.

Allergan holds a New Drug Application for Viberzi® (eluxadoline), which is approved for the treatment of irritable bowel syndrome. Id. at *1. Both Sun and MSN submitted Abbreviated New Drug Applications to sell generic Viberzi® tablets and filed Paragraph IV certifications against several of Allergan’s patents. Id.

At trial, Sun argued that Allergan’s ‘179, ‘291, ‘792, ‘516 patents were invalid for lack of written description. Id. at *2. Sun further argued that Allergan’s ‘356 patent was invalid for obviousness-type double patenting. Id. MSN argued that the ‘627 and ‘291 patents were invalid for lack of written description and enablement. Id. at *3.

Written Description

Key Takeaways:

  • When claims do not include a feature described in the embodiments of an invention, the specification needs to demonstrate that the feature is either optional or not necessary in order to satisfy the written description requirement.
  • Incorporation by reference of exemplary members of a claimed genus does not provide sufficient written description support where the specification does not disclose common structural features or other evidence that the patentee was in possession of embodiments that incorporate the broader genus.
  • A single representative species is insufficient to satisfy written description when the genus is broad and the art is unpredictable.

Allergan v. Sun

Sun’s written description arguments revolved around the absence of “glidants” in the claims asserted by Allergan. Id. at *5-*11. Glidants are agents used to improve the flow characteristics of a powder mixture. Id. at *6.

Sun argued that there was no written description support for claims that did not require a glidant. Id. The inventions of the asserted patents are oral formulations of eluxadoline and the processes for preparing and administering those formulations, but the specification only disclosed a narrow group of formulations that all used a glidant. Id. Sun argued, and Judge Andrews agreed, that nothing in the specification described or suggested that the inventors had a formulation without a glidant. Id. Citing ICU Med., Judge Andrews found that Allergan’s asserted claims lacked written description, as the specification failed to disclose a formulation that did not have a glidant or where a glidant would be understood as optional. Id. (citing ICU Med., Inc. v. Alaris Med. Sys., Inc., 558 F.3d 1368 (Fed. Cir. 2009)).

Allergan’s arguments to the contrary failed. Id. at *7-*11. Judge Andrews disagreed that a person of ordinary skill in the art would understand that a glidant, by definition, is an optional excipient, finding that “a POSA would generally understand that a glidant can be necessary for some formulations” and “a POSA would understand that using a glidant in a formulation would be a signal that it was necessary in order to achieve sufficient flow properties, unless noted otherwise.” Id. at *7. Judge Andrews also disagreed that a POSA would understand that whether a glidant is included in the formulation was not important to the invention. Id. at *8. As “a POSA would understand that a formulation needs to have sufficient flow, a POSA would not understand that the formulations of the claimed invention would have sufficient flow without a glidant based on the disclosure of the patent specification.” Id.

Lastly, Allergan argued that the specification did describe formulations in which a glidant is optional, but again Judge Andrews disagreed. Id. at *10-*11. Citing Ariad Pharms., Inc. v. Eli Lilly & Co., Judge Andrews reasoned that the patent specification here did not need to show actual reduction to practice that the glidant was optional, but instead must show constructive reduction to practice of a formulation which the glidant is optional, or at least not included. Id. at *11 (citing 598 F.3d 1336, 1352 (Fed. Cir. 2010)). Judge Andrews found that Allergan’s general descriptions of mixing eluxadoline with excipients in the specification did not show that Allergan had possession of a formulation where the glidant was optional. Id. Specifically, the patent specification did not disclose a formulation that would have sufficient flow characteristics without a glidant. Id. Thus, the asserted claims were invalid for lack of written description. Id.

Allergan v. MSN

Allergan’s asserted claims against MSN covered formulations of eluxadoline that used any “filler” and any “disintegrant” at specified amounts, which was “a broad genus.” Id. at *15. MSN argued that the asserted claims were invalid for lack of written description because the specification only disclosed formulations made with the same limited number of disintegrants and fillers. Id. at *15-*16.

Despite appropriately incorporating by reference another patent that listed several suitable disintegrants and fillers, Judge Andrews found that the specification did not disclose the use of disintegrants or fillers as a functional category. Id. at *16. Instead, the specification only disclosed formulations of eluxadoline using the same disintegrant (crospovidone) and fillers (mannitol and SMCC). Id. at *15. Further, the specification failed to disclose common structural features for fillers and disintegrants or structural or chemical properties that would allow a POSA to identify viable disintegrants and fillers. Id. at *16. Relying on the knowledge of a POSA, the patentee failed to disclose that SMCC as a filler or crospovidone as a disintegrant can be adequately substituted in the context of the claimed formulation. Id. at *18. While the specification disclosed that “active ingredients, generally, can be mixed with excipients, including disintegrants and fillers,” this disclosure was inadequate because it failed to indicate that the patentee possessed formulations that used alternatives to SMCC or crospovidone. Id. at *19. Allergan’s disclosures may have rendered other formulations obvious, but that was insufficient to satisfy written description. Id.

Based on this analysis, Judge Andrews found that the specification disclosed only one representative species. Id. Allergan argued that the single representative species was enough to satisfy written description, but Judge Andrews disagreed. Id. While one representative species may be sufficient, “the level of detail or number of representative species that must be disclosed varies with the particular facts.” Id. Here, the genus claimed was quite broad, with the incorporated reference identifying “12-17 examples of fillers and 9-15 examples of disintegrants, while also indicating that those lists are not comprehensive.” Id. at *20. Additionally, the art claimed is not predictable, as the specification itself warned. Id. Due to the breadth of the genus and the low predictability of the art, more than one representative species was required to claim the broad genus of formulations with any disintegrant and any filler. Id. at *21. With only one representative species disclosed, the specification did not provide adequate written description for the asserted claims, rendering them invalid. Id.

Obviousness-Type Double Patenting

Key Takeaway:

  • When analyzing obviousness-type double patenting, a court compares patent expiration dates, not filing or issuance dates, and cannot consider equitable concerns.

Allergan asserted the ‘356 patent, one of three patents from the same family with the same priority date, against Sun. Id. at *2. The ‘356 patent was issued before the other patents, but because of awarded patent term adjustment, it expired after them. Id. at *21. The three patents covered eluxadoline and were not patentably distinct. Id.

The Federal Circuit recently ruled in In re Cellect, LLC that “[obviousness-type double patenting] for a patent that has received [patent term extension], regardless of whether or not a terminal disclaimer is required or has been filed, must be based on the expiration date of the patent after [patent term extension] has been added.” ––– F.4th ––––, 2023 WL 5519716, at *9 (Fed. Cir. Aug. 28, 2023). Moreover, obviousness-type double patenting depends solely on patent expiration dates and should not be influenced by equitable concerns. Allergan at *22 (citing In re Cellect, 2023 WL 5519716 at *10). Applying this ruling for the first time, Judge Andrews determined that because the ‘356 patent was not patentably distinct from the other patents, and the expiration date of the ‘356 patent with patent term extension fell after the later-issued patents, the ‘356 patent was invalid for obviousness-type double patenting. Id. The fact that the ’356 patent was “first filed, first issued” was irrelevant. Id.