In a recent decision, the Federal Circuit affirmed Delaware District Court’s finding of invalidity based on failure to define the scope of the invention and to meet the written description requirements of 35 USC § 112.  IBSA Institut Biochimique, S.A. v. Teva Pharm. USA, Inc., 966 F.3d 1374 (Fed. Cir. 2020).  The pharmaceutical patent ‘390 was issued for IBSA’s Tirosint® – a soft gel capsule containing a thyroid hormone levothyroxine.  IBSA filed suit after Teva sought to market a generic version of the drug by filing an Abbreviated New Drug Application with a Paragraph IV Certification that the ‘390 patent is invalid.

The issue revolved around the use of the term “half-liquid.”  One of the claimed embodiments was a pharmaceutical composition of thyroid hormone in a soft elastic capsule, with the capsule consisting of an outer shell of gelatin material and the inner phase active ingredient in the form of a liquid or “half-liquid.”

The District Court agreed with Teva that the term “half-liquid” is indefinite and thus the related claims invalid.   The District Court considered both intrinsic evidence (the claims, specification and prosecution history) and extrinsic evidence (e.g., dictionary definitions) to identify how a person of ordinary skill in the art would interpret the meaning of the term.

The patent holder argued that a person of ordinary skill in the art would understand “half-liquid” and “semi-liquid” to be synonymous, and that a “semi-liquid” has a thick consistency between solid and liquid.  Moreover, the patent claimed priority from an Italian Patent Application which used the term “semiliquido” in the same places where the ’390 patent used “half-liquid,” and where a certified translation of the Italian Application prepared for IBSA in 2019 used “semi-liquid.”  However, the district court observed, and the Federal Circuit agreed, that the field of invention of patent ‘390 was significantly different from the Italian Patent Application. The differences between the ’390 patent and the Italian Application’s use of the terms “half-liquid” and “semiliquido” supported the conclusion that the word choice was intentional.  The courts also considered that during prosecution a proposed dependent claim used the term “semi-liquid” while the independent claim used the term “half-liquid” – evidence that the applicant did not mean  “semi-liquid” and “half-liquid” to be synonymous, and that the two terms have different scope.

Examining the specifications, the term “half-liquid” was listed disjunctively among other possible components of the inner phase:  “a liquid, a half-liquid, a paste, a gel, an emulsion or a suspension comprising the liquid (or half-liquid) vehicle and the thyroid hormone together with possible excipients.”  Thus a “half-liquid” is not a paste or a gel.  Yet pastes and gels fall somewhere between and a liquid and a solid, and would qualify as “half-liquid” under the patent holder’s own proposed construction of the term.

The Federal Circuit next examined extrinsic evidence – the patent holder and its expert failed to identify any scientific dictionary or journal defining the term “half-liquid.”  And the patent holder’s expert admitted during his deposition that “semi-liquid” and “half-liquid” and not necessarily synonymous.  Thus the boundaries of “half-liquid” are not defined.  Finding no clear error in the district court’s determination, the Federal Circuit agreed those skilled in the art were not informed about the scope of the invention.  This decision demonstrates that, in addition to making sure that key terms are adequately defined in the specification, the applicant should not use different terminology in the U.S. application than used in the priority application without considering whether those changes will introduce ambiguity in defined terms or otherwise change the scope of the U.S. application.

This alert is not a substitute for advice of counsel on specific legal issues.

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