Tirosint®/levothyroxine sodium

Case Name: IBSA Institut Biochimique, S.A. v. Teva Pharms. USA, Inc., No. 2019-2400 (Fed. Cir. July 31, 2020) (Circuit Judges Prost, Reyna, and Hughes presiding; Opinion by Prost, C.J.) (Appeal from D. Del., Andrews, J.)

Drug Product and Patent(s)-in-Suit: Tirosint® (levothyroxine sodium); U.S. Pat. No. 7,723,390 (“the ’390 Patent”)

Nature of the Case and Issue(s) Presented: The ’390 patent claimed pharmaceutical formulations used to treat thyroid disorders. The parties’ primary dispute was the claim construction of “half-liquid.” The intrinsic record did not define “half-liquid.” IBSA argued that this term meant “semi-liquid, i.e., having a thick consistency between solid and liquid.” Teva argued that the term was indefinite, or, in the alternative, that it should be construed as “a non-solid, non-paste, non-gel, non-slurry, non-gas substance.”

IBSA presented evidence that an earlier Italian Application used the term “semiliquido” in the same places that the ’390 patent used “half-liquid,” indicating that a POSITA would understand “half-liquid” and “semi-liquid” to be synonyms. But the district court explained that there were a number of differences between the certified translation and the ’390 patent specification and gave no weight to that document. The district court also noted that, during prosecution, the applicant proposed a dependent claim using the term “semi-liquid,” which depended from an independent claim that recited a “half-liquid.” As to the extrinsic record, the district court found that IBSA failed to present evidence that the term “half-liquid” was known in the art.

The district court next attempted to determine whether a skilled artisan could nevertheless ascertain a reasonably certain meaning for “half-liquid.” Based on the claim language, the district court noted that “half-liquid” was neither a liquid nor a solid. Further, reading the specification, a POSITA would have understood that a “half-liquid” was not, or at least was not necessarily, a gel or a paste. And after reviewing the prosecution history, the district court determined that the applicant disclaimed some portion of the claim’s scope that might have otherwise qualified as a half-liquid. In the end, the district court determined that ambiguity rendered it impossible for a POSITA to know, with reasonable certainty, the scope of the term “half-liquid” and found the ‘390 patent invalid as indefinite. The Federal Circuit affirmed.

Why Teva Prevailed: The Federal Circuit noted that the claim language did not make “half-liquid” reasonably clear. It next looked to the specification and concluded that the passage explaining that “said soft capsule contains an inner phase consisting of a liquid, a half-liquid, a paste, a gel, an emulsion or a suspension comprising the liquid (or half-liquid) vehicle and the thyroid hormones together with possible excipients in suspension or solution” provided no greater clarity. As to the prosecution history, the Federal Circuit agreed with Teva’s conclusion that a POSITA would consider the different usage of “half liquid” and “semiliquido” in the Italian Application to be intentional, indicating that the different words had different scopes.