District Court Dismisses Entresto® Antitrust Suit, Holding Drug-Product Patent Properly Listed in Orange Book

Statutory Background

The Hatch-Waxman Act requires innovator drug companies to list in the Food and Drug Administration (FDA) publication Approved Drugs with Therapeutic Equivalence Evaluations (commonly known as the Orange Book) each patent that “claims the drug for which the applicant submitted the application and is a drug substance (active ingredient) patent or a drug product (formulation or composition) patent,” and for which a claim of infringement could reasonably be asserted.21 U.S.C. § 355(b)(1)(A)(viii).

To incentivize brand-name pharmaceutical companies to conduct the expensive and difficult pediatric clinical studies necessary for a drug’s pediatric use, FDA can grant pediatric exclusivity, which adds six months of exclusivity to the life of each Orange Book-listed patent.21 U.S.C. § 355a.

Entresto and the ’659 Patent

Novartis held numerous patents related to Entresto, of which it listed 10 in the Orange Book, including U.S. Patent No. 8,101,659 (the ’659 Patent). Claim 1 of the ’659 Patent recites a pharmaceutical composition comprising valsartan, sacubitril, and a pharmaceutically acceptable carrier “administered in combination in about a 1:1 ratio.” Novartis also obtained separate patents on a later-discovered noncovalent valsartan-sacubitril complex used in Entresto, referred to as LCZ696. When Entresto was granted pediatric exclusivity, the six months of regulatory exclusivity was added to the life of all Orange Book-listed patents, including the ’659 Patent.

The Antitrust Suit

The Iron Workers Local 580 Insurance Fund, a self-insured health and welfare fund, filed suit on August 29, 2025 (No. 1:25-cv-07230 (S.D.N.Y.). The fund asserted numerous antitrust and torts claims under the laws of dozens of states. Each of these claims was premised on the alleged improper listing of the ’659 Patent in the Orange Book. The fund’s theory was that Entresto’s active ingredient is LCZ696, the valsartan-sacubitril complex found in Entresto. The fund then alleged that because the ’659 Patent did not claim LCZ696, it did not claim the drug for which Novartis submitted the Entresto New Drug Application (NDA), and that but for the improper listing, pediatric exclusivity would not have attached and generics would have launched six months earlier. Novartis, represented by a team of Latham & Watkins antitrust, intellectual property, and complex commercial litigators, moved to dismiss on December 17, 2025, and the court heard oral argument on September 14, 2026.

The Court’s Decision

The court focused on whether the ’659 Patent claimed the drug for which Novartis submitted the Entresto NDA. The court determined that “claiming” meant “particularly pointing out and distinctly claiming” the subject matter as the invention. Construing the Orange Book listing statute with reference to FDA’s corresponding regulations, the court held that a drug product (composition or formulation) patent must claim the drug’s active ingredients, as a composition, within the drug’s dosage form.Iron Workers Local 580 Ins. Fund v. Novartis Pharms. Corp., No. 1:25-cv-07230 (LJL), Dkt. No. 86 (S.D.N.Y. Sept. 23, 2026) at *33-37.

To identify Entresto’s active ingredients, the court looked to the FDA-approved Entresto label. It observed that while the label lists “active ingredients: sacubitril and valsartan” and gives the quantity of each, the term “LCZ696” appears nowhere on the label. The court reasoned that the presence of noncovalent bonds connecting the two active ingredients does not change the drug’s active ingredient and that the label’s description of the complex no more makes it an active ingredient than its description of pill color.Id. at *38-41. The court observed that Congress and FDA treat noncovalent variations as immaterial for a variety of regulatory purposes and thus concluded that the presence of a complex is not a critical feature of “the drug” that FDA approves as safe and effective.

Practical Implications for Pharmaceutical Manufacturers

For brand-name pharmaceutical manufacturers, the decision carries several implications:

• Physical form and solid-state features need not be claimed for patent listing in the Orange Book. Innovator drug companies typically file the foundational patent claiming a drug’s active ingredient early. The specific physical form that is ultimately commercialized, whether a particular salt, hydrate, polymorph, cocrystal, or complex, is often identified years later during formulation work. If a patent had to claim that exact form to “claim the drug,” a great many composition and active-ingredient patents listed in the Orange Book would suddenly be open to attack as improperly listed. Judge Liman rejected this argument, and innovator drug companies can continue to follow the long-standing practice of listing drug product patents in the Orange Book that claim the active ingredient(s) in their approved dosage form (e.g., tablet, solution), regardless of whether they claim the exact physical form of the active ingredient(s).
• Anchor listing decisions to the FDA-approved label. The court treated the approved label, especially its statutorily required identification and quantity of each active ingredient, as the authoritative definition of “the drug.” In Orange Book listing decisions, manufacturers should consider how the label identifies active ingredients, proportions of those ingredients (if any), and dosage form.
• Expect continued scrutiny of Orange Book listings. Improper listing claims are an increasingly common argument raised against innovator drug companies. This decision offers a framework for early dismissal where the listed patent claims the approved active ingredients.

Key Takeaways

Judge Liman’s decision provides a detailed analysis of Orange Book listing requirements for drug product patents and the requirement that a patent “claim the drug.” The ruling affirms the long-standing practice of listing Orange Book patents that claim a drug’s active ingredients, even if they do not claim the physical form those active ingredients take in the drug product.