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| July 30, 2025
Eye Therapies, LLC v. Slayback Pharma, LLC (Precedential)
Date of Decision: June 30, 2025
Before TARANTO and STOLL, Circuit Judges, and SCARSI, District Judge. Opinion drafted by SCARSI, District Judge.
Summary:
Eye Therapies appeals from a final written decision of the Patent Trial and Appeal Board (the “Board”) holding all claims of U.S. Patent No. 8,293,742 (“the ’742 patent”) unpatentable. Eye Therapies challenges (1) the Board’s construction of the phrase “consisting essentially of” and (2) the Board’s conclusion that all claims of the ’742 patent would have been obvious over the prior art. For reasons explained below, the CAFC reversed the Board’s claim construction of the “consisting essentially of” limitation, vacate its obviousness finding, and remand for further proceedings. The first challenged by Eye Therapies will be discussed in detail.
As relevant to the appeal, independent claim 1 recites in part “A method for reducing eye redness consisting essentially of administering brimonidine…” Independent claim 3 has a similar limitation.
During patent prosecution, the examiner rejected a prior version of these claims that used the open-ended transition phrase “comprising” instead of the current “consisting essentially of” language. In view of the open-ended claim language, the examiner found the claims anticipated by U.S. Patent No. 6,242,442 (“Dean”), which disclosed the administration of both brimonidine and brinzolamide. In response, the applicant replaced “comprising” with the phrase “consisting essentially of”. Thereafter, the examiner allowed the amended claims, citing the applicant’s argument “that the presently claimed methods do not require the use of any other active ingredients in addition to brimonidine,” i.e., brinzolamide.
Slayback filed an inter partes review petition of the ’742 patent and the Board entered a final written decision determining all challenged claims were unpatentable. On claim construction, “the parties dispute[d] whether the scope of the claims includes the use of additional drugs along with low-dose brimonidine.” The Board noted that “the use of ‘consisting essentially of’ ‘signals that the invention necessarily includes the listed ingredients [but] is open to unlisted ingredients that do not materially affect the basic and novel properties of the invention,’” in accordance with the phrase’s typical meaning. The Board rejected Eye Therapies’ arguments that the prosecution history demonstrated that “consisting essentially of” in this context should be read to claim a method for administering brimonidine as the sole active ingredient, reasoning:
During prosecution, the patentee asserted that “[o]ne of the basic and novel characteristics of the presently claimed methods is that they do not require the use of any other active ingredients (emphasis added) in addition to brimonidine.” But, unlike Patent Owner, we do not read the prosecution history as prohibiting the use of any other active ingredients besides brimonidine. To do so would construe the semi-open-ended transition phrase “consisting essentially of” to have the same scope as the closed transition phrase “consisting of.”
Rather, the Board concluded that “under the proper scope of the claims and consistent with the prosecution history, the claimed methods cannot include additional active ingredients that are required to perform the method.” Here, the Board took the position that “because the Specification states that low-dose brimonidine alone can significantly reduce hyperemia, if there are additional agents beyond low-dose brimonidine administered to a patient that may also reduce eye redness . . . those additional agents would not materially affect the basic and novel characteristics of the invention.” Thus, the Board ultimately held that “the transitional phrase ‘consisting essentially of’ does not preclude the use of additional active agents that may also cause vasoconstriction and reduction of hyperemia along with low-dose brimonidine.” The CAFC disagreed.
That is, the CAFC concluded the Board erred in its construction of the phrase “consisting essentially of” as allowing the coadministration of active ingredients other than brimonidine. That, given the prosecution history, the phrase as used in the ’742 patent precluded the use of active ingredients other than brimonidine.
The CAFC stated that the transitional phrase “consisting essentially of” generally “has long been understood to permit inclusion of components not listed in the claim, provided that they do not ‘materially affect the basic and novel properties of the invention.’” However, “a patentee can alter that typical meaning” That, limiting statements in the patent prosecution history can “inform the meaning of the claim language by demonstrating how the inventor understood the invention and whether the inventor limited the invention in the course of prosecution, making the claim scope narrower than it would otherwise be.”
Thus, the CAFC agreed with Eye Therapies that the prosecution history here supported an atypical meaning of “consisting essentially of.”
Comments:
- A prosecution history of a patent comes into play in the context of claim construction. While this could be a good thing (as in the case here) always be mindful of making statements or argument that unnecessary define or characterize the claimed invention that may unintentionally cause a narrower than desired claim construction. In this same regard, be mindful of statements made by an Examiner that also unnecessarily define or characterize the claimed invention.
