Addressing invalidity due to obvious-type double patenting (ODP) based on later-filed-related patents, the US Court of Appeals for the Federal Circuit reversed a district court’s application of In re Cellect (Fed. Cir. 2023) and held that the later-filed, earlier-expiring continuation patents were not available as ODP references against the earlier-filed, later-expiring patent. Allergan USA, Inc. v. MSN Labs Private Ltd., Case No. 24-1061 (Fed. Cir. Aug. 13, 2024) (Lourie, Dyk, Reyna JJ.)

In 2015, the US Food and Drug Administration approved a new drug application for a drug sold by Allergan to treat the symptoms of irritable bowel syndrome. In 2019, Sun Pharma filed an abbreviated new drug application (ANDA) seeking to market a generic version of the drug. Allergan then sued Sun Pharma and MSN Labs for infringement of four patents related to the drug. One of the patents, which claims a compound of the drug, had been granted almost three years of patent term adjustment (PTA) and was followed by two more patents from continuation applications in the same patent family. The other three patents all claimed tablet forms of the drug. The claims of one of the patents recited that a glidant was optional while the claims of the other two patents did not require a glidant at all.

The US District Court for the District of Delaware held a three-day bench trial and concluded that the asserted claim of the compound patent was invalid under the ODP doctrine and that the claims of the three tablet patents were invalid for lack of written description. On the issue of ODP, the district court found Allergan’s “first-filed, first-issued” distinction “immaterial.” The district court stated that “[w]hen analyzing ODP, a court compares patent expiration dates, rather than filing or issuance dates.” Allergan appealed.

The Federal Circuit reversed on both issues. The Court held that the claims of the later-filed, earlier-expiring continuation patents were not available as ODP references against the first patent because the purpose of the ODP doctrine is to prevent patentees from obtaining a second patent to effectively extend the life of the first patent. The Federal Circuit explained that the district court misread Cellect as binding it to solely consider expiration dates in the ODP analysis. The Court explained that Cellect only controls to the extent that it requires a court to consider the later-filed patent’s expiration date (i.e., the expiration date after the addition of PTA) in its ODP analysis, not the expiration date that it would have shared with the reference patents in the absence of a PTA award. The panel majority emphasized that it does not follow that the later-filed patent must be invalidated by the earlier-filed reference patents simply because it expires later. The majority noted that “Cellect does not address, let alone resolve, any variation of the question presented here – namely, under what circumstances can a claim properly serve as an ODP reference – and therefore has little to say on the precise issue before us.”

The Federal Circuit also found written description support based on two embodiments where a glidant was not required and based on the original claim from the patent application, which did not recite a glidant.

Judge Dyk filed a separate opinion concurring with the double-patenting decision but dissenting as to written description. He concluded that the district court’s written description finding was supported by unrebutted expert testimony that a glidant would be used in every formulation and by a specification listing of optional ingredients that did not include a glidant.