IP Law Daily, PATENT NEWS: High Court declines review in Entresto enablement dispute, preserving Novartis patent, (Dec 16, 2025)

By Saurabh Kashyap, B.A., M.A., LL.B., LL.M.

MSN Pharmaceuticals’ petition had urged the Supreme Court to reject the Federal Circuit’s exclusion of after-arising technology from the §112(a) validity inquiry.

The U.S. Supreme Court has denied MSN Pharmaceuticals’ petition for a writ of certiorari, leaving undisturbed a Federal Circuit decision that upheld the validity of Novartis’s U.S. Patent No. 8,101,659 (the ’659 patent) covering the pharmaceutical composition of valsartan and sacubitril in Entresto—Novartis’ famed heart failure drug. The denial, issued on December 15, 2025, came without comment, concluding a protracted battle over whether Section 112(a) of the Patent Act requires disclosure and enablement of after-arising technology—innovations not known at the time of patent filing but falling within the literal scope of the claims (MSN Pharmaceuticals, Inc. v. Novartis Pharmaceuticals Corp, Dkt. No. 25-225 (U.S. cert. denied Dec. 15, 2025)).

Background. The dispute originated in 2019 when Novartis brought suit in the District of Delaware against MSN Pharmaceuticals, Inc. and other generic drug manufacturers following their submission of Abbreviated New Drug Applications (ANDAs) seeking to market generic versions of Entresto®. Novartis asserted claims 1–4 of the ’659 patent, which describes a pharmaceutical composition combining valsartan and sacubitril in a 1:1 ratio. Although the patent does not mention a later-developed complex form of these compounds, Novartis contended that its claims covered both physical mixtures and complexes.

The district court adopted a broad construction of “combination” that included the complex form. However, it held that the patent failed the written description requirement under 35 U.S.C. § 112(a) because it did not show possession of the complex as of the 2002 filing date. The court invalidated the patent on this basis but rejected arguments on lack of enablement and obviousness.

On appeal, the Federal Circuit reversed the written description invalidity finding, holding that the claimed invention was sufficiently disclosed and that the complex was not “what is claimed.” It further affirmed that the claims were enabled and not obvious, concluding that the specification allowed a skilled artisan to make and use the claimed composition as of the filing date. The panel cited In re Hogan, 559 F.2d 595 (C.C.P.A. 1977), to support the view that later-developed technologies cannot retroactively render a patent invalid under § 112.

The petition. On August 22, 2025, MSN filed a petition for certiorari seeking Supreme Court review of the Federal Circuit’s decision. The petition presented the question: “Whether, in a patent-infringement suit, a court may consider after-arising technology to hold that the patent is invalid under § 112(a) of the Patent Act.” MSN argued that the Federal Circuit's exclusion of after-arising technology from the validity analysis created a conflict in precedent and undermined the requirements of disclosure and enablement under § 112.

MSN invoked Amgen Inc. v. Sanofi, 598 U.S. 594 (2023), in support of its argument that a patent’s specification must enable the entire class of claimed compositions, including those discovered after filing. The petition further cited Ariad Pharmaceuticals, Inc. v. Eli Lilly & Co., 598 F.3d 1336 (Fed. Cir. 2010) and The Incandescent Lamp Patent, 159 U.S. 465 (1895). It distinguished the Federal Circuit’s ruling from prior decisions, such as Idenix Pharmaceuticals LLC v. Gilead Sciences Inc., 941 F.3d 1149 (Fed. Cir. 2019) and Plant Genetic Systems v. DeKalb Genetics, 315 F.3d 1335 (Fed. Cir. 2003), which treated after-arising technology as relevant to validity determinations.

MSN characterized the Federal Circuit’s decision as having created a “Hogan-Entresto loophole” and argued that the panel improperly relied on Hogan to exempt later-developed technology from the written description and enablement requirements. The petition asserted that the lower court’s approach permits patentees to claim broad subject matter without the corresponding obligation to teach how to make and use it. MSN further contended that the Federal Circuit's claim construction diverged improperly between infringement and validity contexts, contrary to Markman v. Westview Instruments, Inc., 517 U.S. 370 (1996).

The petition also noted the Federal Circuit’s denial of en banc rehearing in this case and in similar earlier matters, asserting that the absence of further appellate review perpetuates doctrinal inconsistency.

Conclusion. With the denial of certiorari, the Supreme Court has declined to resolve a growing split over the role of after-arising technology in patent validity inquiries under §112(a). The Federal Circuit’s decision remains controlling, reinforcing a bifurcated approach that permits infringement liability for post-filing developments without requiring their disclosure or enablement.

The Case is Dkt. No. 25-225.

Attorneys: Amit R. Vora (Kasowitz LLP) for MSN Pharmaceuticals, Inc., MSN Life Sciences Private Ltd., and MSN Laboratories Private Ltd. Deanne E. Maynard (Morrison & Foerster LLP) for Novartis Pharmaceuticals Corp.

Companies: MSN Pharmaceuticals, Inc.; MSN Life Sciences Private Ltd.; MSN Laboratories Private Ltd.; Novartis Pharmaceuticals Corp.

News: Patent FedCirNews