Case Name: Acadia Pharms. Inc. v. Aurobindo Pharma Ltd., No. 20-985-GBW, 2023 WL 8622048 (D. Del. Dec. 13, 2023) (Williams, J.)

Drug Product and Patent(s)-in-Suit: Nuplazid® (pimavanserin tartrate); U.S. Patent No. 7,601,740 (“the ’740 patent”)

Nature of the Case and Issue(s) Presented: The only disputed issue was the validity of claim 26 of the ’740 patent, which recited a tartrate salt of pimavanserin. The ’740 patent issued on October 13, 2009, from U.S. Patent Application No. 10/759,561 (“the ’561 application”), which was filed January 15, 2004. The USPTO calculated 980 days of patent term adjustment (“PTA”) for the ’740 patent. The ’740 patent also received a 1,315-day patent term extension (“PTE”) for FDA delay.

Defendant argued that claim 5 of U.S. Patent 9,566,271 (“the ’271 patent”)—that recited a method for treating hallucinations by administering the tartrate salt of pimavanserin—rendered claim 26 of the ’740 patent invalid for obvious-type double patenting (“OTDP”). The ’271 patent issued from U.S. Patent Application No. 11/416,527 (“the ’527 application”), filed on May 3, 2006. The ’527 application initially was a continuation of the ’561 application. During prosecution, on July 1, 2009, Acadia changed the ’527 application to a divisional of the ’561 application. The ’271 patent issued on February 14, 2017, and expires on January 15, 2024. The parties cross moved for summary judgment. The court granted Acadia’s summary judgment motion.

Why Acadia Prevailed: The parties disputed the proper interpretation of 35 U.S.C. § 121. That statute creates a safe harbor—for a parent application and its divisional application claiming overlapping subject matter—to protect from OTDP. The court framed the issue as follows: “whether the language in § 121, which requires the divisional patent be filed ‘before the issuance of the patent on the other application’ and ‘as a result’ of a restriction requirement, applies when the challenged patent is the original patent, not the divisional patent”?

Arcadia argued that § 121 discusses two types of reference patents: (i) a patent issuing on an application with respect to which a requirement for restriction has been made; and (ii) a patent issuing on an application filed as a result of such a requirement. Conversely, MSN argued that “the divisional application” refers to the reference patent, which is “filed as a result of a restriction requirement.” In other words, § 121 applies only when the reference patent is filed as a result of a restriction requirement “before the issuance of the patent on the other application.”

The court explained that the best guidance on § 121 was a Federal Circuit decision stating that the statute was meant to “shelter[] from attack a divisional application or … the original application or any patent issued on either of them, if the divisional application is filed before the issuance of the patent on the other application.” Based on that dicta, the court agreed with Acadia’s interpretation that the “divisional application” that must be filed pre-issuance is a challenged patent, not a reference patent. The court found that the ’271 patent was filed “as a result of” the original ’740 patent. For this reason, the ’740 patent was not invalid for OTDP.