Case: 18-2232   Document: 87     Page: 1   Filed: 03/13/2020




   United States Court of Appeals
       for the Federal Circuit
                 ______________________

  KAKEN PHARMACEUTICAL CO., LTD., BAUSCH
         HEALTH COMPANIES INC.,
                Appellants

                            v.

     ANDREI IANCU, UNDER SECRETARY OF
   COMMERCE FOR INTELLECTUAL PROPERTY
    AND DIRECTOR OF THE UNITED STATES
      PATENT AND TRADEMARK OFFICE,
                   Intervenor
             ______________________

                       2018-2232
                 ______________________

     Appeal from the United States Patent and Trademark
 Office, Patent Trial and Appeal Board in Nos. IPR2017-
 00190, IPR2017-01429.
                  ______________________

                 Decided: March 13, 2020
                 ______________________

     JOHN D. LIVINGSTONE, Finnegan, Henderson, Farabow,
 Garrett & Dunner, LLP, Atlanta, GA, argued for appel-
 lants. Also represented by JEFFREY JACOBSTEIN, Boston,
 MA; SAMHITHA MEDATIA, ANTHONY A. HARTMANN, CORA
 RENAE HOLT, BARBARA RUDOLPH, Washington, DC.

    NICHOLAS THEODORE MATICH, IV, Office of the Solicitor,
 United States Patent and Trademark Office, Alexandria,
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 2                  KAKEN PHARMACEUTICAL CO., LTD. v. IANCU




 VA, argued for intervenor. Also represented by THOMAS W.
 KRAUSE, WILLIAM LAMARCA, ROBERT J. MCMANUS, BRIAN
 RACILLA, FARHEENA YASMEEN RASHEED.
                  ______________________

 Before NEWMAN, O’MALLEY, and TARANTO, Circuit Judges.
 TARANTO, Circuit Judge.
     U.S. Patent No. 7,214,506 describes and claims meth-
 ods for topically treating fungal infections in human nails.
 The parties here treat Kaken Pharmaceutical Co. and
 Bausch Health Companies Inc. (together, Kaken) as the pa-
 tent owner. Acrux Limited and Acrux DDS Pty. Ltd. (to-
 gether, Acrux), which no longer are parties to this
 proceeding, successfully sought an inter partes review of
 all claims of the ’506 patent under 35 U.S.C. § 311–319.
 The Patent Trial and Appeal Board of the Patent and
 Trademark Office ultimately determined that all claims of
 the ’506 patent are unpatentable for obviousness. Acrux
 DDS Pty. Ltd. v. Kaken Pharm. Co., Ltd., No. IPR2017-
 00190, 2018 WL 2761408 (P.T.A.B. June 6, 2018).
     Kaken appeals. The Director of the Patent and Trade-
 mark Office, who intervened after Acrux withdrew, defends
 the Board’s decision. We agree with Kaken on its principal
 contention—that the Board erred in its claim construction
 of one claim limitation. Because the Board’s obviousness
 analysis materially relied on its erroneous claim construc-
 tion, we cannot affirm the Board’s unpatentability deter-
 mination. We reverse the claim construction, vacate the
 Board’s decision, and remand the matter to the Board.
                              I
                              A
     The ’506 patent, titled “Method For Treating Ony-
 chomycosis,” provides a series of interlocking definitions.
 The patent states that “[o]nychomycosis” is a class of “su-
 perficial mycosis” that affects the “nail of [a] human or an
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 animal.” ’506 patent, col. 9, lines 32–35. The umbrella
 term, “superficial mycosis,” encompasses infections that at-
 tack tissues of the “skin or visible mucosa.” Id., col. 5, lines
 20–26. According to the patent, “skin” is “a tissue including
 the three layers being epidermis, de[r]mis and subcutane-
 ous tissue, accompanied by pilus (hair), nail, [and various
 glandulae] as appendages.” Id., col. 4, lines 54–57. In turn,
 the “term ‘nail’ includes nail plate, nail bed, nail matrix,
 further side nail wall, posterial nail wall, eponychium and
 hyponychium which make up a tissue around thereof.” Id.,
 col. 4, lines 65–67.
    Each of these structures is labeled in the following di-
 agram:




 J.A. 2435. Although the patent contains its own defini-
 tions, including of “nail” and of “skin” (the latter including
 “nail”), evidence before the Board explained that common
 usage differs from the patent’s definitions. The “nail plate”
 is the “horny appendage of the skin that is composed
 mainly of keratin” and is “commonly called the nail.” J.A.
 1236. By contrast, the “eponychium and hyponychium” are
 the “skin structures surrounding the nail.” J.A. 1276.
     One specific form of onychomycosis is “tinea unguium,”
 which is caused by fungi of the Trichophyton species. ’506
 patent, col. 9, lines 40–45. Two types of Trichophyton
 fungi, Trichophyton rubrum and Trichophyton men-
 tagrophytes, are the most common causes of onychomycosis
 in humans. ’506 patent, col. 9, lines 35–38. Accordingly,
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 4                    KAKEN PHARMACEUTICAL CO., LTD. v. IANCU




 the patent refers to “onychomycosis” and “tinea unguium”
 interchangeably. E.g., id., col. 3, lines 41–45, col. 14, lines
 60–63.
      Traditionally, onychomycosis was treated with oral
 medications. Id., col. 2, lines 25–27. Because those oral
 medications required long treatment periods and could
 cause gastrointestinal disorders, it was “desired to develop
 a topical preparation.” Id., col. 2, lines 27–39. Topical
 treatments, however, were largely ineffective—most treat-
 ments “could not sufficiently permeate the thick keratin in
 [the] nail plate.” Id., col. 2, lines 40–45. It is a stated object
 of the patent to provide a topical treatment that is effective
 more quickly than oral medications “due to good permea-
 bility, good retention capacity and conservation of high ac-
 tivity in nail plate as well as . . . potent antifungal activity.”
 Id., col. 3, lines 42–47.
      The ’506 patent teaches a method of topically treating
 onychomycosis with efinaconazole, also referred to as “KP-
 103,” which is a specific kind of azole compound. See id.,
 col. 3, line 52 through col. 4, line 6; id., col. 8, line 23
 through col. 9, line 17. Claim 1, the only independent
 claim, recites:
     1. A method for treating a subject having onychomyco-
        sis wherein the method comprises topically admin-
        istering to a nail of said subject having
        onychomycosis a therapeutically effective amount
        of an antifungal compound represented by the fol-
        lowing formula:
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     wherein, Ar is a non-substituted phenyl group or a phe-
           nyl group substituted with 1 to 3 substituents
           selected from a halogen atom and trifluorome-
           thyl group,
     R1 and R2 are the same or different and are hydrogen
           atom, C1-6 alkyl group, a non-substituted aryl
           group, an aryl group substituted with 1 to 3 sub-
           stituents selected from a halogen atom, trifluo-
           romethyl group, nitro group and C1-16 alkyl
           group, C2-8 alkenyl group, C2-6 alkynyl group, or
           C7-12 aralkyl group,
     m is 2 or 3,
     n is 1 or 2,
     X is nitrogen atom or CH, and
     *1 and *2 mean an asymmetric carbon atom.
 Id., col. 17, line 33 through col. 18, line 28. The two possi-
 bilities covered by the language “X is [a] nitrogen atom or
 CH” are, respectively, a triazole or an imidazole. Claim 2,
 which depends on claim 1, requires that the “compound
 represented by the formula (II)” is KP-103, which is the tri-
 azole version. Id., col. 18, lines 29–32; see id., col. 9, lines
 15–17. The patent states that the “effectiveness of the KP-
 103 used as an antifungal in the present invention for ony-
 chomycosis has not been confirmed, but its antifungal ac-
 tivity has been already known.” Id., col. 9, lines 22–25.
                                B
     In November 2016, Acrux petitioned for an inter partes
 review of claims 1 and 2 of the ’506 patent, relying on two
 sets of references. The first set consists of three references:
 Japanese Patent Application No. 10-226639 (JP ’639); U.S.
 Patent No. 5,391,367; and R.J. Hay et al., Tioconazole nail
 solution—an open study of its efficacy in onychomycosis, 10
 CLINICAL AND EXPERIMENTAL DERMATOLOGY 111 (1985)
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 6                   KAKEN PHARMACEUTICAL CO., LTD. v. IANCU




 (Hay). Acrux argued that each of those references inde-
 pendently teaches a method of topically treating ony-
 chomycosis with various azole compounds. The second set
 of references consists of two references: H. Ogura et al.,
 Synthesis and Antifungal Activities of (2R,3R)-2-Aryl-1-az-
 olyl-3-(substituted amino)-2-butanol Derivatives and Topi-
 cal Antifungal Agents, 47 CHEM. PHARM. BULL. 1417 (1999)
 (Ogura); and Abstracts F78, F79, and F80, 36
 INTERSCIENCE CONFERENCE ON ANTIMICROBIAL AGENTS
 AND CHEMOTHERAPY 113 (1996) (Kaken Abstracts). Acrux
 argued that both of those references disclose KP-103 as an
 effective antifungal agent.
     Acrux challenged both claims of the ’506 patent as un-
 patentable for obviousness, stating six (related) grounds,
 each one drawing a reference from the first set and a refer-
 ence from the second set. Specifically, Acrux argued obvi-
 ousness over JP ’639 in combination with Ogura or the
 Kaken Abstracts, obviousness over the ’367 patent in com-
 bination with Ogura or the Kaken Abstracts, and obvious-
 ness over Hay in combination with Ogura or the Kaken
 Abstracts. In its final written decision, the Board held
 claims 1 and 2 unpatentable for obviousness over JP ’639,
 the ’367 patent, and Hay, each in combination with the Ka-
 ken Abstracts. Acrux, 2018 WL 2761408, at *12–26.
     During the inter partes review, Kaken proposed that
 the phrase “treating a subject having onychomycosis”
 means “treating the infection at least where it primarily
 resides in the keratinized nail plate and underlying nail
 bed.” Id. at *4. The Board rejected Kaken’s construction
 as too narrow, concluding that “the express definition of on-
 ychomycosis includes superficial mycosis, which in turn is
 expressly defined as a disease that lies in the skin or visible
 mucosa.” Id. at *5. The Board also found significant that
 the express definition of “nail includes the tissue or skin
 around the nail plate, nail bed, and nail matrix.” Id. Ac-
 cordingly, the Board concluded, “treating onychomycosis”
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 KAKEN PHARMACEUTICAL CO., LTD. v. IANCU                   7



 includes treating “superficial mycosis that involves disease
 of the skin or visible mucosa.” Id. at *6. Applying that
 construction, the Board determined that a skilled artisan
 would have been motivated to combine the cited references
 and that Kaken’s objective indicia of non-obviousness de-
 served little weight. Id. at *20–26.
    Kaken timely appealed. We have jurisdiction under 28
 U.S.C. § 1295(a)(4)(A).
                              II
     Kaken challenges the Board’s construction of “treating
 a subject having onychomycosis.” According to Kaken, the
 Board’s construction ignores the ’506 patent’s core innova-
 tion—a topical treatment that can easily penetrate the
 tough keratin in the nail plate. Kaken asks us to reverse
 the claim construction and either to reverse the obvious-
 ness determination or to vacate it and remand for applica-
 tion of the proper construction.
                              A
     We review the Board’s claim construction de novo and
 any underlying factual findings for substantial evidence.
 Teva Pharmaceuticals USA, Inc. v. Sandoz, Inc., 135 S. Ct.
 831, 840–41 (2015); Wasica Finance GmbH v. Continental
 Automotive Systems, Inc., 853 F.3d 1272, 1278 (Fed. Cir.
 2017). The parties accept that, in this matter, the claims
 must be given their broadest reasonable interpretation.
 We hold, in light of the specification and prosecution his-
 tory, that the Board’s claim construction is unreasonable.
 The broadest reasonable interpretation of “treating a sub-
 ject having onychomycosis,” consistent with Kaken’s con-
 struction, is penetrating the nail plate to treat a fungal
 infection inside the nail plate or in the nail bed under it.
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 8                   KAKEN PHARMACEUTICAL CO., LTD. v. IANCU




                                1
      The ’506 patent’s specification characterizes “ony-
 chomycosis” in a way that links to three other crucial pas-
 sages in the specification—two that provide express
 definitions of other terms and one that characterizes an-
 other term. Thus, after defining the terms “skin” and
 “nail,” and characterizing “superficial mycosis,” the speci-
 fication declares that “onychomycosis” is “a kind of the
 above-mentioned superficial mycosis, in the other word a
 disease which is caused by invading and proliferating in
 the nail of human or an animal.” ’506 patent, col. 9, lines
 32–35. This assertion about onychomycosis conveys that
 the disease covered by the term has two basic features: (1)
 it is a disease of the “nail” and (2) it is a kind of superficial
 mycosis. Contrary to the Board’s conclusion, however, that
 characterization, when coupled with the other three linked
 specification passages, does not compel the conclusion that
 “onychomycosis” reasonably is understood to involve inva-
 sion of any part of what is defined as the “nail,” including
 parts other than the nail plate or nail bed, such as skin in
 its ordinary sense.
     More specifically, the Board relied on the ’506 patent’s
 definition of “nail”: the “term ‘nail’ includes nail plate, nail
 bed, nail matrix, further side nail wall, posterial nail wall,
 eponychium and hyponychium which make up a tissue
 around thereof.” Id., col. 4, lines 65–67; see Acrux, 2018
 WL 2761408, at *5. That definition includes skin struc-
 tures surrounding the nail plate. But the Board drew an
 unwarranted inference from that broad definition. As a
 matter of ordinary meaning, a statement that a particular
 disease invades the body would not imply that it can invade
 any part of the body. So too, when the specification says
 that “onychomycosis” is a disease involving invasion of the
 “nail,” it does not compel the conclusion that the disease
 can invade any part of the defined “nail.” A disease that
 invades the nail plate or bed only is still a disease that
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 KAKEN PHARMACEUTICAL CO., LTD. v. IANCU                      9



 invades the “nail” as defined. Thus, this language alone
 does not support the Board’s conclusion that an infection of
 any individual structure of the nail constitutes onychomy-
 cosis.
      The Board also relied on the specification’s characteri-
 zation of “superficial mycosis.” The specification says that
 superficial mycosis is a kind of mycosis in which “[a] seat
 of the disease lie[s] in the skin or visible mucosa,” id., col.
 5, lines 23–24, in contrast to deep mycosis, which lies “in
 viscus, central nervous system, subcutaneous tissue, mus-
 cle, [h]orn or articulation,” id., col. 5, lines 24–26. The
 Board concluded that, because onychomycosis is stated to
 be a type of superficial mycosis, “which in turn is expressly
 defined as a disease that lies in the skin or
 visible mucosa,” onychomycosis “includes infections of skin
 contrary to [Kaken’s] interpretation of this term to require
 infection of the nail plate and nail bed.” Acrux, 2018 WL
 2761408, at *5. 1
     The “superficial mycosis” characterization is no more
 decisive in supporting the Board’s conclusion than is the
 “nail” definition. Specifically, the Board’s inference runs
 counter to the specification’s capacious definition of “skin”
 as including “nail”: “a tissue including the three layers be-
 ing epidermis, de[r]mis and subcutaneous tissue, accompa-
 nied by pilus (hair), nail, [and certain glandulae] as
 appendages.” ’506 patent, col. 4, lines 54–57 (emphasis
 added). Because of that definition, the assertion that ony-
 chomycosis is a type of disease that lies in the “skin” in no
 way excludes onychomycosis from being limited to the


     1    We understand the Board’s statement that “the ex-
 press definition of onychomycosis includes superficial my-
 cosis,” Acrux, 2018 WL 2761408, at *5, to mean simply that
 the specification characterizes onychomycosis as a type of
 superficial mycosis.
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 10                  KAKEN PHARMACEUTICAL CO., LTD. v. IANCU




 “nail.” The characterization of “superficial mycosis” allows
 that possibility and does not mean that every type of su-
 perficial mycosis affects every type of “skin” structure.
     The Board did not draw any inference specifically from
 the contrast with “deep mycosis.” The specification de-
 scribes deep mycosis as affecting “subcutaneous tissue,”
 but the patent also defines “skin” as including “subcutane-
 ous tissue.” Compare id., col. 5, lines 23–26 with id., col. 4,
 lines 54–57. The overlap reinforces the general lesson that
 the specification passages on which the Board relied do not
 provide clarity about the reasonable bounds of the class of
 structures that must be infected for a disease to constitute
 “onychomycosis.”
      Other parts of the specification, which explain that an
 effective topical treatment would need to penetrate the nail
 plate, support Kaken’s construction. A patent’s statement
 of the described invention’s purpose informs the proper
 construction of claim terms, including when the task is to
 identify the broadest reasonable interpretation. See In re
 Power Integrations, Inc., 884 F.3d 1370, 1376–77 (Fed. Cir.
 2018) (the patent at issue “strives to eliminate unnecessary
 components,” so it would be unreasonable to construe a
 claim term to include a “bulky [component]”). The ’506 pa-
 tent briefly describes topical treatments known in the prior
 art. It notes that those treatments were largely ineffective
 because they “could not sufficiently permeate the thick ker-
 atin in [the] nail plate.” ’506 patent, col. 2, lines 40–44.
 Accordingly, the ’506 patent explains, an effective topical
 treatment must have “good permeability, good retention
 capacity and conservation of high activity in [the] nail
 plate.” Id., col. 3, lines 40–48. That discussion, in stating
 the “object of [the] present invention” relevant to the claims
 at issue, id., col. 3, lines 40–41, supports Kaken’s construc-
 tion. Treating an infection of the skin surrounding the nail
 plate alone would not require all those properties,
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 KAKEN PHARMACEUTICAL CO., LTD. v. IANCU                       11



 including “high activity in [the] nail plate.” Id., col. 3, lines
 40–48 (emphasis added).
     The Board discounted that evidence based on a flawed
 understanding of the relationship between onychomycosis
 and tinea unguium. The Board reasoned that the patent’s
 description of an effective topical treatment is unhelpful
 because it is preceded by the phrase “a therapeutic agent
 for onychomycosis which exhibits the effect on tinea un-
 guium by topical application” and tinea unguium “is in-
 cluded in the definition of onychomycosis, but is not co-
 extensive with it.” Acrux, 2018 WL 2761408, at *6 (citing
 ’506 patent, col. 3, lines 41–45). Although the Board is cor-
 rect that onychomycosis is broader than tinea unguium, it
 is not broader in a way that is significant for this analysis.
 The patent explains that tinea unguium is onychomycosis
 “caused by [the] Trichophyton species” of fungus and con-
 trasts tinea unguium with “[o]nychocandidadis caused by
 [the] Candida species or onychomychosis (sensu stricto)
 caused by the other fungus.” ’506 patent, col. 9, lines 40–
 44. That onychomycosis can be caused by fungi other than
 the Trichophyton species does not decrease the probative
 value, for determining the location of the infection, of the
 patent’s description of an effective topical treatment for
 tinea unguium.
                                2
      The prosecution history—which includes, specifically,
 statements made by Kaken to overcome a rejection and the
 examiner’s statements explaining withdrawal of the rejec-
 tion based on those statements—provides decisive support
 for limiting the claim phrase at issue to a plate-penetrating
 treatment of an infection inside or under the nail plate. A
 patent’s prosecution history can “inform the meaning of the
 claim language by demonstrating how the inventor under-
 stood the invention and whether the inventor limited the
 invention in the course of prosecution, making the claim
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 12                 KAKEN PHARMACEUTICAL CO., LTD. v. IANCU




 scope narrower than it would otherwise be.” Phillips v.
 AWH Corp., 415 F.3d 1303, 1317 (Fed. Cir. 2005); see also
 Hynix Semiconductor Inc. v. Rambus Inc., 645 F.3d 1336,
 1350 (Fed. Cir. 2011) (prosecution history is strong evi-
 dence of what a skilled artisan “would have understood dis-
 puted claim language to mean”). Particularly useful are
 “express representations made by or on behalf of the appli-
 cant to the examiner to induce a patent grant,” which in-
 clude “arguments made to convince the examiner that the
 claimed invention meets the statutory requirements of nov-
 elty, utility, and nonobviousness.” Standard Oil Co. v.
 American Cyanamid Co., 774 F.2d 448, 452 (Fed. Cir.
 1985). Prosecution history plays this role in applying the
 broadest-reasonable-interpretation standard.      See Mi-
 crosoft Corp. v. Proxyconn, Inc., 789 F.3d 1292, 1298
 (Fed. Cir. 2015), overruled on other grounds by Aqua
 Prods., Inc. v. Matal, 872 F.3d 1290 (Fed. Cir. 2017)
 (en banc). In this case, Kaken’s statements during prose-
 cution, followed by the examiner’s statements, make clear
 the limits on a reasonable understanding of what Kaken
 was claiming.
      The ’506 patent issued from a divisional application of
 U.S. Patent Application No. 10/031,929, which originally
 had seventeen claims. Divisional dated Oct. 14, 2003, at
 35–39, in Appl. No. 10/685,266. When Kaken submitted its
 divisional application (the ’266 application), it included a
 preliminary amendment that reduced the number of claims
 to four: claims 2–17 were cancelled and claims 18–20 were
 added. Preliminary Amendment dated Oct. 14, 2003, at 3–
 4, in Appl. No. 10/685,266. Independent claim 18 described
 a “method for treating [a] subject having onychomycosis”
 using a compound having “formula (I).” Preliminary
 Amendment dated Oct. 14, 2003, at 3; see ’506 patent, col.
 3, lines 54–63. Claim 19, which depended on claim 18, re-
 quired a compound having “formula (II).” Preliminary
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 KAKEN PHARMACEUTICAL CO., LTD. v. IANCU                     13



 Amendment dated Oct. 14, 2003, at 3; see ’506 patent, col.
 8, lines 28–39.
      The examiner, believing that claims 18–20 were di-
 rected to a method of treating general mycosis, initially re-
 jected Kaken’s application for obviousness-type double
 patenting over claims 9–12 of U.S. Patent No. 5,620,994.
 The ’994 patent describes a “fungicide” containing the same
 compound described by formula (II) of the ’506 patent. ’994
 patent, Abstract; see ’506 patent, col. 8, lines 28–39. While
 independent claim 1 of the ’994 patent claims that com-
 pound, ’994 patent, col. 17, line 51, through col. 18, line 19,
 claim 9 of the ’994 patent claims a “process for treating my-
 cosis” using the compound of claim 1, id., col. 18, lines 46–
 48. The examiner first explained that the “formula pre-
 sented in instantly claimed Claim 19 [of the ’266 applica-
 tion] is exactly the same as that in Claim [1] of [the ’994]
 patent.” Non-Final Rejection dated June 14, 2006, at 4, in
 Appl. No. 10/685,266; J.A. 1571. The examiner added that
 claims 18–20 were not “patentably distinct” from claims 9–
 12 of the ’994 patent because “[c]laims 9–12 . . . claim a pro-
 cess to treat mycosis which again is a generic terminology
 for ‘onychomycosis’ via administering the compound of for-
 mula in Claim 1.” Non-Final Rejection dated June 14,
 2006, at 4; J.A. 1571.
     Kaken responded by submitting an amendment that
 cancelled claim 1, clarified the wording of claim 18, and as-
 serted the important difference between mycosis and ony-
 chomycosis. Noting that the “[t]reatment of onychomycosis
 significantly differs from the general treatment of mycoses
 claimed in ’994,” Kaken explained that “[o]nychomycosis is
 a condition that specifically affects the nail plate.” Amend-
 ment filed Sept. 14, 2006, at 10, in Appl. No. 10/685,266
 (emphasis added); J.A. 1589. Kaken further argued that
 the “present invention shows the unexpected ability of an
 azolylamine derivate to penetrate nail and be retained by
 the nail.” Amendment filed Sept. 14, 2006, at 10 (emphasis
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 14                  KAKEN PHARMACEUTICAL CO., LTD. v. IANCU




 added); J.A. 1589. Accordingly, Kaken concluded, the re-
 jection should be withdrawn.
     The examiner credited Kaken’s explanation and with-
 drew the rejection. In allowing the claims, the examiner
 stated, under the heading “Examiner’s Reasons for Allow-
 ance,” that “unexpectedly and in contrast to previously
 evaluated compositions/methods, the instantly claimed
 method cures the onychomycosis because the medicament
 upon direct administration to the nail, penetrates through
 the nail plate and eradicates the infection at the site.” No-
 tice of Allowability dated Dec. 26, 2006, at 5, in Appl. No.
 10/685,266 (emphasis added); J.A. 1608. The examiner
 also suggested that Kaken cancel claim 18 and make claim
 19 independent, which Kaken did, and the resulting claims
 19 and 20 became claims 1 and 2 of the issued ’506 patent.
 Compare Notice of Allowability dated Dec. 26, 2006, at 3–4
 with ’506 patent, col. 17, line 34 through col. 18, line 32.
       This exchange would leave a skilled artisan with no
 reasonable uncertainty about the scope of the claim lan-
 guage in the respect at issue here. Kaken is bound by its
 arguments made to convince the examiner that claims 1
 and 2 are patentable. See Standard Oil, 774 F.2d at 452.
 Thus, Kaken’s unambiguous statement that onychomyco-
 sis affects the nail plate, and the examiner’s concomitant
 action based on this statement, make clear that “treating
 onychomycosis” requires penetrating the nail plate to treat
 an infection inside the nail plate or in the nail bed under
 it. 2


      2   The intrinsic evidence in this case is decisive, mak-
 ing it unnecessary to review the expert evidence. See
 SIPCO, LLC v. Emerson Electric Co., 939 F.3d 1301, 1307
 (Fed. Cir. 2019) (“To the extent the Board considered ex-
 trinsic evidence when construing the claims, we need not
 consider the Board’s findings on the evidence because the
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 KAKEN PHARMACEUTICAL CO., LTD. v. IANCU                 15



     Accordingly, we reverse the Board’s claim construction.
                             B
     The Board relied on its erroneous claim construction
 throughout its consideration of facts that were part of its
 obviousness analysis. For example, in determining that a
 skilled artisan would have been motivated to combine JP
 ’639, the ’367 patent, or Hay with the Kaken Abstracts, the
 Board rejected Kaken’s primary argument as inconsistent
 with the Board’s claim construction. Before the Board, Ka-
 ken argued that because the Kaken Abstracts document
 experiments testing KP-103 in vitro and in skin (in the or-
 dinary, not patent-defined sense), a skilled artisan would
 not have been motivated to use KP-103 to treat onychomy-
 cosis. See Acrux, 2018 WL 2761408, at *20. The Board
 concluded that this argument “relies upon an improperly
 narrow interpretation of the claim terms ‘nail’ and ‘ony-
 chomycosis’” and “hinge[s] on a requirement that is not in
 the challenged claims, treatment of onychomycosis in the
 nail plate or nail bed.” Id. Accordingly, the Board dis-
 missed Kaken’s arguments as “misdirected.” Id.
     Similarly, the Board rejected Kaken’s objective indicia
 of non-obviousness because it concluded, relying on the
 claim construction we have concluded is erroneous, that
 there is no nexus between the objective indicia and the
 challenged claims. In its Patent Owner’s response, Kaken


 intrinsic record is clear.”); Eidos Display, LLC v. AU Op-
 tronics Corp., 779 F.3d 1360, 1365 (Fed. Cir. 2015). With
 one possible exception, the evidence on both sides is uni-
 form about the nail-penetrating character of onychomyco-
 sis addressed by the patent. The one possible exception
 involves an entirely superficial, on-the-nail fungus that
 commonly can be just scraped off. See Acrux, 2018 WL
 2761408, at *5. The intrinsic evidence is inconsistent with
 including treatment of that fungus within the claim scope.
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 16                  KAKEN PHARMACEUTICAL CO., LTD. v. IANCU




 identified KP-103 as the “active pharmaceutical ingredient
 in Jublia®, the first FDA-approved monotherapy for the
 topical treatment of onychomycosis.” J.A. 1121. Kaken
 made several objective-indicia arguments based on
 Jublia®: that Jublia® produced unexpected results; that
 Jublia® has had significant commercial success; that
 Jublia® received industry praise; and that Jublia® fulfilled
 a long-felt, but unmet need. See Acrux, 2018 WL 2761408,
 at *22–26. But before considering any of those arguments,
 the Board pointed to evidence that the FDA approved
 Jublia® as a “topical treatment of onychomycosis of the toe-
 nails,” and Jublia®’s label directs the user to “apply Jublia®
 to affected toenails once daily.” J.A. 1809; see Acrux, 2018
 WL 2761408, at *23. Because “Jublia®[] is directed to
 treatment of specific fungal infections in toenails, and not
 to a ‘nail’ or to treat ‘onychomycosis,’” the Board explained,
 the “method for Jublia®’s use is not reasonably commensu-
 rate with the [scope] of the challenged claims.” Acrux, 2018
 WL 2761408, at *23. Thus, the Board concluded, the objec-
 tive indicia presented by Kaken “do not weigh in favor of a
 finding that the subject matter of the claims would not
 have been obvious.” Id. at *24.
     The foregoing determinations are infected by the erro-
 neous claim construction. In this court, the Director has
 sought to support the Board’s factual findings with little or
 no reliance on the claim construction we have held to be
 erroneous. But that effort is more a reconstruction of the
 Board’s analysis than a description of the Board’s actual
 reasoning. We conclude that the appropriate course in this
 case, as in so many others involving a reversal of a Board
 claim construction, is to vacate the Board’s decision and re-
 mand the matter. See, e.g., Arista Networks, Inc. v. Cisco
 Sys., Inc., 908 F.3d 792, 798 (Fed. Cir. 2018); Dell Inc. v.
 Acceleron, LLC, 818 F.3d 1293, 1300 (Fed. Cir. 2016). We
 do not prejudge whether the correct claim construction per-
 mits the same factual findings or obviousness conclusion,
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 KAKEN PHARMACEUTICAL CO., LTD. v. IANCU                  17



 let alone what factual findings should be made on the evi-
 dence when the correct claim construction is used. Nor do
 we prejudge what effect the withdrawal of Acrux has on
 how the Board should proceed on remand.
                             III
     For the foregoing reasons, we reverse the Board’s claim
 construction, vacate the Board’s final written decision, and
 remand the matter to the Board.
     Costs awarded to appellants.
  REVERSED IN PART, VACATED, AND REMANDED
