Federal Circuit IP

In re Entresto

By Frank Morton-Park Published February 19, 2025

CAFC Opinion No. 2023-2218, 2023-2220, 2023-2221, Decided Jan. 10, 2025

(Lourie, Prost, Reyna)

Overview: Written description must be assessed based on knowledge in the art at the time of filing.

Background

  • Novartis owns the ’659 patent, which claims administering valsartan and sacubitril in combination, and covers Entresto (a valsartan-sacubitril complex), an FDA-approved drug used to treat heart failure.
  • The valsartan-sacubitril complex used in Entresto was discovered four years after the ’659 priority date.
  • Generic drug manufacturers (Defendants) submitted an ANDA seeking FDA approval to market and sell a generic version of Entresto.
  • Novartis sued Defendants in district court alleging that the ANDA filing directly infringed claims 1-4 of the ’659 patent; Defendants challenged the patent’s validity.
  • District court gave “wherein [said valsartan and sacubitril] are administered in combination” its plain and ordinary meaning, which encompasses valsartan-sacubitril complexes.
  • The district court found that the claims were not invalid for obviousness, lack of enablement, or indefiniteness, but invalidated the claims for lack of written description because the valsartan-sacubitril complexes were unknown and thus axiomatically the inventors could not have possession of them.

Issue: Whether a patent is invalid for lack of written description when it does not describe later-existing state of the art.

Holding: Reversed determination that the claims were invalid for lack of written description and affirmed that the claims were not invalid for obviousness or lack of enablement.

Federal Circuit Analysis

  • “A specification adequately describes an invention when it reasonably conveys to those skilled in the art that the inventor had possession of the claimed subject matter as of the filing date.” In re Entresto, 125 F.4th 1090, 1097 (Fed. Cir. 2025) (citations and quotations omitted).
  • The ’659 patent does not claim valsartan-sacubitril complexes, so does not need to describe them.
  • The ’659 patent describes administration of valsartan and sacubitril in combination, and the benefits of this teaching, in a way that plainly shows the inventors had possession of a composition of valsartan and sacubitril administered in combination.

Takeaway

  • Written description is assessed as of the filing date.
  • When preparing patent applications, do not worry about adequately describing later-arising inventions that may be covered by the claims.