Mylan Pharmaceuticals Inc. v. Research Corporation Tech. , 914 F.3d 1366 ( 2019 )


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  •   United States Court of Appeals
    for the Federal Circuit
    ______________________
    MYLAN PHARMACEUTICALS INC.,
    BRECKENRIDGE PHARMACEUTICAL, INC.,
    ALEMBIC PHARMACEUTICALS LTD.,
    Appellants
    v.
    RESEARCH CORPORATION TECHNOLOGIES,
    INC.,
    Appellee
    ______________________
    2017-2088, 2017-2089, 2017-2091
    ______________________
    Appeals from the United States Patent and Trade-
    mark Office, Patent Trial and Appeal Board in Nos.
    IPR2016-00204,     IPR2016-01101,     IPR2016-01242,
    IPR2016-01245.
    ______________________
    Decided: February 1, 2019
    ______________________
    STEVEN WILLIAM PARMELEE, Wilson, Sonsini, Goodrich
    & Rosati, PC, Seattle, WA, argued for all appellants.
    Appellant Mylan Pharmaceuticals Inc. also represented
    by MICHAEL T. ROSATO, JAD ALLEN MILLS; ADEN M.
    ALLEN, NICOLE W. STAFFORD, Austin, TX.
    MATTHEW L. FEDOWITZ, Buchanan Ingersoll & Rooney
    PC, Alexandria, VA, for appellant Breckenridge Pharma-
    2      MYLAN PHARMACEUTICALS INC. v. RESEARCH CORPORATION
    TECHS., INC.
    ceutical, Inc.
    TODD S. WERNER, Carlson, Caspers, Vandenburgh,
    Lindquist & Schuman, PA, Minneapolis, MN, for appel-
    lant Alembic Pharmaceuticals Ltd. Also represented by
    SARAH STENSLAND, Patterson Thuente Pedersen, PA,
    Minneapolis, MN.
    JACK B. BLUMENFELD, Morris, Nichols, Arsht & Tun-
    nell LLP, Wilmington, DE, argued for appellee. Also
    represented by ALEXA HANSEN, Covington & Burling LLP,
    San Francisco, CA; JENNIFER L. ROBBINS, New York, NY;
    BETH S. BRINKMANN, PRISCILLA GRACE DODSON, EVAN
    SMITH KRYGOWSKI, GEORGE FRANK PAPPAS, Washington,
    DC.
    ______________________
    Before LOURIE, BRYSON, and WALLACH, Circuit Judges.
    LOURIE, Circuit Judge.
    Mylan Pharmaceuticals Inc. (“Mylan”), Breckenridge
    Pharmaceutical, Inc. (“Breckenridge”), and Alembic
    Pharmaceuticals, Ltd. (“Alembic”) (collectively, “Appel-
    lants”) appeal from the final written decision of the U.S.
    Patent and Trademark Office Patent Trial and Appeal
    Board (“the Board”) in an inter partes review concluding
    that claims 1–13 of U.S. Reissue Patent 38,551 (“the ’551
    patent”) are not unpatentable. See Argentum Pharm.
    LLC v. Research Corp. Techs., IPR 2016-00204, 
    2017 WL 1096590
    , at *1–2 (P.T.A.B. Mar. 22, 2017) (“Decision”).
    For the reasons detailed below, we affirm.
    BACKGROUND
    Epilepsy is a neurological disorder that affects about
    one percent of the human population. It is characterized
    by two or more unprovoked seizures occurring more than
    24 hours apart. Epilepsy can be associated with condi-
    tions affecting the structure of the brain, but, for the vast
    MYLAN PHARMACEUTICALS INC. v. RESEARCH CORPORATION       3
    TECHS., INC.
    majority of affected individuals, no specific cause can be
    identified. While there is no known cure for epilepsy,
    treatment can include both drug therapy and surgery, and
    most patients are treated via long-term administration of
    anticonvulsant drugs to prevent seizures. The nature and
    severity of seizures varies considerably across the patient
    population, and treatment is typically tailored for each
    specific patient.
    Research Corporation Technologies, Inc. (“RCT”) owns
    the ’551 patent, which discloses and claims enantiomeric
    compounds and pharmaceutical compositions useful in the
    treatment of epilepsy and other central nervous system
    (“CNS”) disorders. Claim 1 recites:
    1. A compound in the R configuration having the
    formula:
    wherein
    Ar is phenyl which is unsubstituted or
    substituted with at least one halo group;
    Q is lower alkoxy, and
    Q1 is methyl.
    ’551 patent col. 38 ll. 8–23.
    4       MYLAN PHARMACEUTICALS INC. v. RESEARCH CORPORATION
    TECHS., INC.
    At issue here are claims 8–13. 1 Claim 8 depends from
    claim 1 and recites “[t]he compound according to claim 1
    which            is           (R)-N-benzyl-2-acetamido-3-
    methoxypropionamide,” referred to in the patent as
    “BAMP” and referred to herein as lacosamide:
    Claim 9 claims lacosamide in 90 percent or greater
    purity, claim 10, therapeutic compositions comprising the
    claimed compounds, and claims 11–13, use of the com-
    pounds for treating central nervous system disorders. 
    Id.
    col. 38 ll. 39–51. Because arguments have not been made
    concerning the separate claims, we will consider them
    together, as did the Board.
    1   Before the Board, Appellants challenged claims 1–
    13, but, since this appeal was taken, claims 1–7 have been
    voluntarily cancelled in a separate, ex parte reexamina-
    tion proceeding. See Citation of Supplemental Authority,
    Mylan Pharm. Inc. v. Research Corp. Techs., No. 2017-
    2088 (Fed. Cir. Apr. 23, 2018), ECF No. 73. Because there
    is no case or controversy regarding the finally cancelled
    claims, we rule only on the still-existing claims 8–13. See
    Fresenius USA, Inc. v. Baxter Int’l, Inc., 
    721 F.3d 1330
    ,
    1347 (Fed. Cir. 2013) (litigation became moot because of
    the cancellation of claims).
    MYLAN PHARMACEUTICALS INC. v. RESEARCH CORPORATION     5
    TECHS., INC.
    On November 23, 2015, Argentum Pharmaceuticals
    LLC (“Argentum”) petitioned for inter partes review
    (“IPR”) of the ’551 patent. In its petition, Argentum
    challenged claims 1–13 on eight grounds. The Board only
    instituted on two grounds involving three references:
    (1) obviousness of claims 1–9 over Kohn 1991 2 and Sil-
    verman 3 and (2) obviousness of claims 10–13 over Kohn
    1991, Silverman, and U.S. Patent 5,378,729 (“the ’729
    patent”). 4 The instituted grounds appear in the petition
    as ground 3A and ground 3B.
    In its argument, Argentum advanced a lead com-
    pound analysis. It relied on Kohn 1991 for disclosure of
    compound 3l, its proffered lead compound. Kohn 1991,
    authored by the named inventor of the ’551 patent, Dr.
    Harold Kohn, discloses a series of functionalized amino
    acids (“FAAs”) with anticonvulsant activity. Dr. Kohn
    observed that FAA racemates with N-benzylamide moie-
    ties and acetylated amino groups provided potent protec-
    tion against seizures in mice. For his research presented
    in the 1991 paper, Dr. Kohn began with (R,S)-2-
    acetamido-N-benzyl-2-methylacetamide as a lead com-
    pound and replaced the α-methyl group, denoted in the
    structure below as “X,” with functionalized nitrogen,
    oxygen, and sulfur substituents:
    2    Harold Kohn et al., Preparation and Anticonvul-
    sant Activity of a Series of Functionalized α-Heteroatom-
    Substituted Amino Acids, 34 J. Medicinal Chemistry
    2444 (1991); J.A. 2404–12.
    3  Richard B. Silverman, The Organic Chemistry of
    Drug Design and Drug Action (1st ed. 1992); J.A. 2413–
    61.
    4  The application that led to the ’551 patent was
    filed before March 16, 2013, and the pre-Leahy–Smith
    America Invents Act, Pub L. No. 112-29, 
    125 Stat. 284
    (2011), version of § 103 applies.
    6    MYLAN PHARMACEUTICALS INC. v. RESEARCH CORPORATION
    TECHS., INC.
    Dr. Kohn then evaluated the potency of the compounds in
    mice, reporting for each the effective dosage for 50 percent
    of the tested population (“ED50”).
    Based on the reported ED50 values, Dr. Kohn conclud-
    ed that “in the most potent analogues (2d, 3l, and 3n), a
    functionalized oxygen atom existed two atoms removed
    from the α-carbon atom.” J.A. 2407. The most efficacious
    compound (i.e., the compound with the lowest ED50) was
    compound 3l. In compound 3l, NH(OCH3) is at the α-
    carbon position. J.A. 2405. Its structure is as follows:
    To supply a motivation to modify compound 3l, Argen-
    tum relied on Silverman, a book chapter on drug discov-
    ery, design, and development.           Silverman describes
    bioisosterism as a “lead modification approach . . . useful
    to attenuate toxicity or to modify . . . activity. ” J.A. 2430.
    He specifically defines bioisosteres as “substituents or
    groups that have chemical or physical similarities, and
    which produce broadly similar biological properties.” Id.
    As relevant here, Silverman explains that “classical
    MYLAN PHARMACEUTICALS INC. v. RESEARCH CORPORATION         7
    TECHS., INC.
    isosteres” are groups with the same number of valence
    electrons but potentially different atoms. Under the
    subheading “[b]ivalent atoms and groups,” he lists the
    following compounds as classical isosteres: –CH2–, –NH–,
    –O–, –S–, and –Se–. Id.
    As a third reference, relevant only to the second insti-
    tuted ground of review, Argentum cited the ’729 patent,
    another patent issued to Dr. Kohn and assigned to RCT.
    The ’729 patent is directed to a genus of FAAs with activi-
    ty “useful in the treatment of epilepsy and other CNS
    disorders.” ’729 patent, Abstract. Specifically, a method
    of treating CNS disorders in animals with a racemate of
    N-benzyl 2-acetamido-3-methoxypropionamide (“racemic
    lacosamide”) is recited in claim 132 of the ’729 patent.
    Based on Argentum’s petition, the Board instituted
    review on (1) obviousness of claims 1–9 over Kohn 1991
    and Silverman and (2) obviousness of claims 10–13 over
    Kohn 1991, Silverman, and the ’729 patent. As for the
    first ground, the Board was “persuaded that [Argentum]
    sufficiently articulate[d] reasoning, with adequate ration-
    al underpinnings, as to why an ordinary artisan would
    have chosen derivative 3l from Kohn 1991 as a lead
    compound for the purposes of making compositions exhib-
    iting anticonvulsant activity.” J.A. 367. The Board noted
    that Kohn 1991 identified compound 3l as “the most
    potent derivative,” and, based on the record at the time, it
    was not persuaded that “potential synthetic or stability
    issues” would have counseled against its selection as a
    lead compound. J.A. 367–68. The Board was also per-
    suaded that “an ordinary artisan reading Silverman
    would have had reason to substitute the amino group
    (–NH–) in the X moiety of NH(OCH3) in derivative 3l from
    Kohn 1991 with a methylene group,” “in an effort to
    attenuate toxicity, modify activity, or positively affect the
    metabolism of a compound.” J.A. 368. That change would
    lead to lacosamide.
    8       MYLAN PHARMACEUTICALS INC. v. RESEARCH CORPORATION
    TECHS., INC.
    As for the second ground, the Board concluded that
    Argentum had adequately supported its contention that
    an ordinary artisan would have had reason to expect “that
    compounds falling within claim 132 of the ’729 patent—
    such as racemic lacosamide and R-lacosamide—would be
    useful for treating CNS disorders, and would have a
    reasonable expectation of success in using them for this
    purpose.” J.A. 372.
    Three days after the Board instituted Argentum’s pe-
    tition, Mylan, Breckenridge, and Alembic each filed their
    own petitions for review with concurrent motions for
    joinder. Each party had been sued for infringement of the
    ’551 patent in 2013, more than a year before the petitions
    were filed. 5 On October 24, 2016, the Board instituted on
    each petition and joined each proceeding with the Argen-
    tum IPR. In its decision permitting joinder, the Board
    noted that Mylan, Breckenridge, and Alembic “agree[d] to
    be limited to an ‘understudy’ role, and limited to evidence
    and arguments presented in the Argentum Petition in
    relation to instituted Grounds 3A–3B.” J.A. 1463.
    Five months later, the Board issued its final written
    decision, concluding that each challenged claim had not
    been shown to be unpatentable. Regarding ground one,
    Petitioners identified two reasons for modifying the
    methoxyamino moiety of compound 3l in Kohn 1991:
    (1) that the methoxyamino moiety was not a common
    moiety in compounds that result in commercial pharma-
    5   UCB, Inc. v. Mylan Pharm. Inc., No. 1:13-cv-
    01214-LPS (D. Del. Jul. 10, 2013); UCB, Inc. v. Alembic
    Pharm. Ltd., No. 1:13-cv-01207-LPS (D. Del. Jul. 10,
    2013); UCB, Inc. v. Breckenridge Pharm., Inc., No. 1:13-
    cv-01211-LPS (D. Del. Jul. 10, 2013). We resolved the
    appeal of these cases in UCB, Inc. v. Accord Healthcare,
    Inc., 
    890 F.3d 1313
     (Fed. Cir. 2018), cert. denied, No. 18-
    441, 
    2018 WL 4899559
     (U.S. Nov. 19, 2018).
    MYLAN PHARMACEUTICALS INC. v. RESEARCH CORPORATION       9
    TECHS., INC.
    ceutical compounds and (2) that the methoxyamino moie-
    ty may present synthetic and stability problems. Accord-
    ing to Petitioners, a person of skill in the art would have
    been motivated to substitute the –NH– group in 3l for a –
    CH2– group because it is a more common and acceptable
    moiety for pharmaceutically active compounds. Further,
    because Kohn 1991 disclosed a ten-fold higher activity for
    3l, which has an R group of –NH(OCH3), over a compound
    with an R group of –NH2, a person of skill in the art
    would have been motivated to substitute the –CH3 group
    with –CH2OCH3.
    Contrary to its views in the institution decision, the
    Board disagreed with Petitioners. It “assum[ed] arguen-
    do, that an ordinary artisan would have selected com-
    pound 3l of Kohn 1991 as a lead compound” but found
    that converting the methoxyamino group would have been
    viewed as undesirable because the compounds in Kohn
    1991 without a methoxyamino or nitrogen-containing
    moiety at the α-carbon had reduced activity. Decision,
    
    2017 WL 1096590
    , at *8–9.
    The Board also credited evidence suggesting that an
    ordinary artisan would have understood the methoxy-
    amino moiety to confer significant activity to the com-
    pound and that substitution of nitrogen for carbon would
    have led to a significantly different conformation and
    biological activity. 
    Id.
     at *10–11. While the Board
    “acknowledge[d] Silverman’s teaching . . . that bioisoster-
    ism has been shown to be useful to attenuate toxicity in
    lead compounds,” it found a lack of “specific evidence
    suggesting an ordinary artisan would have understood
    that modifying the methoxyamino group of Kohn 1991’s
    compound 3l would have reduced that compound’s toxici-
    ty.” Id. at *12.
    Although the Board did proceed to evaluate objective
    indicia of nonobviousness, it nonetheless concluded that
    even without objective evidence of nonobviousness Peti-
    10   MYLAN PHARMACEUTICALS INC. v. RESEARCH CORPORATION
    TECHS., INC.
    tioners failed to meet their burden to establish by a
    preponderance of the evidence that challenged claims 1–9
    would have been obvious. Id. at *13.
    Proceeding to the second ground relating to the de-
    pendent claims, the Board declined to consider Petition-
    ers’ arguments because they incorporated by reference a
    separate ground, Ground 1B, on which the Board did not
    institute review. Specifically, in Ground 1B, Petitioners
    advanced arguments based on a LeGall thesis, a reference
    not at issue in the proceeding as instituted. The Board
    found that the second ground was “based on a conclusory
    assertion referencing a distinct ground of unpatentability
    discussing a different combination of references.” J.A.
    129. Moreover, because it concluded that independent
    claim 1 would not have been obvious over Kohn 1991 and
    Silverman, the Board reasoned that it could not conclude
    that the more limited dependent claims 10–13, the only
    claims at issue in the second ground, would have been
    obvious.
    Of the four petitioners, Mylan, Breckenridge and
    Alembic appealed. RCT challenges whether Appellants
    have standing to challenge the Board’s decision. We have
    jurisdiction for this appeal under 
    28 U.S.C. § 1295
    (a)(4)(A) and 
    35 U.S.C. § 141
    (c). We review the
    Board’s legal determinations de novo, In re Elsner, 
    381 F.3d 1125
    , 1127 (Fed. Cir. 2004), and its fact findings for
    substantial evidence, In re Gartside, 
    203 F.3d 1305
    , 1316
    (Fed. Cir. 2000). A finding is supported by substantial
    evidence if a reasonable mind might accept the evidence
    as sufficient to support the finding. Consol. Edison Co. v.
    NLRB, 
    305 U.S. 197
    , 229 (1938).
    DISCUSSION
    I. STANDING
    As a threshold matter, we first address whether Ap-
    pellants have standing to make this appeal. RCT does not
    MYLAN PHARMACEUTICALS INC. v. RESEARCH CORPORATION         11
    TECHS., INC.
    assert that Appellants lack Article III standing. Appel-
    lee’s Br. 20. However, RCT submits that each Appellant
    lacks standing because it does not fall within the zone of
    interests of 
    35 U.S.C. § 319
    . According to RCT, Appel-
    lants fall outside that zone because RCT brought an
    infringement action against each Appellant more than a
    year before it filed its IPR petition, and each Appellant’s
    petition was therefore time-barred.
    In its institution and joinder decision, the Board exer-
    cised its discretion to join each Appellant as a party to
    Argentum’s IPR as permitted by 
    35 U.S.C. § 315
    (c). J.A.
    670 (“[T]he later Petitioners are joined as parties . . . .”).
    RCT does not challenge the propriety of the Board’s
    joinder decision. However, RCT argues that the “statuto-
    ry scheme here . . . does not authorize Appellants to seek
    federal court review of the Board’s [final written] deci-
    sion.” Appellee’s Br. 18. Its argument is that the initial
    Petitioner, Argentum, would have lacked Article III
    standing to appeal the Board’s decision, because “its IPR
    was limited to an agency matter.” 
    Id.
     at 18–19. The
    parties appear to agree that Argentum, who is not a party
    to this appeal, lacks standing. See Appellants’ Br. 71;
    Appellee’s Br. 20.
    For their part, Appellants maintain that they have an
    express, statutory right to appeal under 
    35 U.S.C. § 319
    because they were joined as petitioners to Argentum’s
    IPR. Appellants’ Br. 70–71. We agree.
    We presume that a statutory cause of action extends
    only to litigants that “fall within the zone of interests
    protected by the law invoked.” Lexmark Int’l, Inc. v.
    Static Control Components, Inc., 
    572 U.S. 118
    , 129 (2014)
    (quoting Allen v. Wright, 
    468 U.S. 737
    , 751 (1984)). The
    zone of interests limitation “always applies and is never
    negated.” 
    Id.
     To determine whether an appellant falls
    within the zone of interests, we apply traditional princi-
    ples of statutory interpretation, asking not “whether in
    12    MYLAN PHARMACEUTICALS INC. v. RESEARCH CORPORATION
    TECHS., INC.
    our judgment Congress should have authorized [the
    appeal], but whether Congress in fact did so.” Id. at 128.
    We begin our analysis on this point with the text of
    the statute. Section 315(c) provides for joinder as follows:
    If the Director institutes an inter partes review,
    the Director, in his or her discretion, may join as a
    party to that inter partes review any person who
    properly files a petition under section 311 that the
    Director, after receiving a preliminary response
    under section 313 or the expiration of the time for
    filing such a response, determines warrants the
    institution of an inter partes review under section
    314.
    (emphasis added). Section 315 thus contemplates the
    joining of petitioners as “parties.” Section 319 then
    provides that “[a] party dissatisfied with the final written
    decision” of the Board “may appeal the decision pursuant
    to sections 141 through 144. Any party to the inter partes
    review shall have the right to be a party to the appeal.”
    (emphasis added).
    “It is a ‘fundamental canon of statutory construction
    that the words of a statute must be read in their context
    and with a view to their place in the overall statutory
    scheme.’” Nielson v. Shinseki, 
    607 F.3d 802
    , 807 (Fed.
    Cir. 2010) (quoting Davis v. Michigan Dep’t of Treasury,
    
    489 U.S. 803
    , 809 (1989)). Joined parties, as provided in
    § 315, may appeal pursuant to § 319. Accepting RCT’s
    argument would require us to read the word “party”
    differently between § 315 and § 319, an argument for
    which RCT provides no support.
    RCT also argues that, because Appellants’ role before
    the Board was limited by agreement and prohibited
    presentation of evidence independent of Argentum, Appel-
    lants’ participation should not be “transformed into a
    right to federal court review.” Appellee’s Br. 19–20. But
    MYLAN PHARMACEUTICALS INC. v. RESEARCH CORPORATION     13
    TECHS., INC.
    § 315 provides the Board with discretion in joinder, and
    that discretion allows for the Board to place requirements
    and limitations on joined parties. RCT points to no sup-
    port for the proposition that a party subject to such re-
    strictions in its IPR should be considered to have less
    standing to appeal than a party under § 319. RCT argues
    that allowing Appellants’ appeal “would constitute an
    end-run around the statutory time-limit for instituting
    IPR proceedings,” id. at 19, but cites no provision in the
    text or legislative history supporting its reading.
    Accordingly, we conclude that Appellants fall within
    the zone of interests of § 319 and are not barred from
    appellate review. We therefore proceed to the merits.
    II. MERITS
    On the merits, Appellants challenge the Board’s non-
    obviousness conclusion. Regarding claims 1–9, Appel-
    lants assert a lead compound analysis, proposing
    compound 3l in Kohn 1991 as the lead. In its final writ-
    ten decision, the Board did not resolve whether compound
    3l was an appropriate lead compound. Instead, it accept-
    ed compound 3l as the lead and concluded that Petitioners
    did not meet their burden to establish a motivation to
    modify that compound. Because we agree with the Board
    that Appellants failed to meet their burden to establish a
    motivation to modify, we likewise need not resolve wheth-
    er compound 3l would have been a suitable lead com-
    pound. Accordingly, for our analysis below, we assume, as
    the Board did, that compound 3l was an appropriate lead
    compound.
    Obviousness is a question of law based on underlying
    factual findings. In re Baxter Int’l, Inc. 
    678 F.3d 1357
    ,
    1361 (Fed. Cir. 2012).
    Appellants first argue that an ordinary artisan would
    have recognized the methoxyamino group in compound 3l
    to be uncommon and to have potential synthetic and
    14   MYLAN PHARMACEUTICALS INC. v. RESEARCH CORPORATION
    TECHS., INC.
    stability problems. According to Appellants, a person of
    skill in the art would then have been motivated to modify
    compound 3l by replacing the amine of its methoxyamino
    group with a methylene link to yield a more stable, syn-
    thetically accessible, pharmaceutically common and
    acceptable moiety.
    In proposing this modification, Appellants rely on the
    principles of bioisosterism as recited in Silverman.
    Appellants submit that, of the “classical bioisosteres” in
    Silverman, only methylene would result in a more phar-
    maceutically common and acceptable compound and
    resolve the potential stability and synthesis concerns
    presented by the methoxyamino moiety. Appellants’ Br.
    23. Appellants maintain that Silverman would have
    motivated a person of skill in the art to replace the amine
    in the methoxyamino group with a methylene link and
    have a reasonable expectation of success having done so.
    Appellants submit that their proposed modification
    was consistent with Kohn 1991, which detailed “‘stringent
    steric and electronic requirements that exist for maximal
    anticonvulsant activity in this class of compounds,’ includ-
    ing the size of the group on the α-carbon.” Id. at 24 (quot-
    ing Kohn 1991, J.A. 2407). According to Appellants, their
    proposed replacement retained a small moiety at the α-
    carbon, which would have satisfied steric requirements
    and would have left the N-benzylamide moiety and acety-
    lated amino group unchanged. Appellants also argue
    that, consistent with Kohn 1991, their proposed modifica-
    tion retained a functionalized oxygen atom two atoms
    removed from the α-carbon atom, which Kohn 1991 dis-
    closed as associated with excellent potency.
    Appellants further contend that their proposed modi-
    fication to compound 3l would have been expected to have
    excellent potency. Specifically, Appellants point to Kohn
    1991’s teaching that a terminal methoxy group added to
    compound 3a resulted in compound 3l, which was ten
    MYLAN PHARMACEUTICALS INC. v. RESEARCH CORPORATION      15
    TECHS., INC.
    times more potent than compound 3a. Before the Board,
    Appellants’ expert, Dr. Wang, testified that a person of
    skill in the art would have reasonably expected a similar
    ten-fold increase in activity from adding a terminal meth-
    oxy group to the methyl compound 2a, yielding a racemic
    mixture of lacosamide with a predicted ED50 value of 7.6
    mg/kg. According to Dr. Wang, this ED50 value would
    have been comparable or better than commercially avail-
    able reference compounds, including phenytoin, pheno-
    barbital, and valproate.
    Notably, Appellants’ predicted potency for “racemic
    lacosamide” was less impressive than that of compound
    3l. Appellants address that fact by stating that a person
    of skill in the art would have sacrificed some potency to
    achieve the superior stability of racemic lacosamide over
    compound 3l. Appellants maintain that a person of skill
    in the art would have had reason to modify 3l to address
    stability, synthetic simplicity, and pharmaceutical famili-
    arity and acceptability, even if doing so would result in
    lower potency.
    As a final point, Appellants argue that a person of
    skill in the art would have had reason to isolate the R
    enantiomer from its “racemic lacosamide” mixture be-
    cause Kohn 1991 teaches that the “anticonvulsant activity
    resided primarily with the R stereoisomer.” Appellants’
    Br. 32 (quoting Kohn 1991, J.A. 2404).
    RCT counters that, while the record supports the idea
    that N–O bonds generally can be labile, the record lacks
    evidence that the N–O bond in compound 3l specifically is
    labile and would have motivated modification. According
    to RCT, such an argument would have been contrary to
    the teaching of Kohn 1991, which remarked that its
    disclosed compounds, including 3l, were stable. RCT also
    suggests that the record is devoid of evidence that the
    potential stability issues with the N–O bond would have
    outweighed other considerations, including potency and
    16   MYLAN PHARMACEUTICALS INC. v. RESEARCH CORPORATION
    TECHS., INC.
    neurotoxicity. Instead, RCT contends that the record
    supports that a person of skill in the art would consider
    all of a compound’s properties together, as the Board did
    in its analysis.
    RCT also argues that Appellants did not provide any
    evidence that “only methylene would result in a more
    pharmaceutically common and acceptable compound and
    resolve the potential stability and synthesis concerns
    presented by the methoxyamino moiety.” Appellee’s Br.
    23. RCT submits that the ED50 values for the methox-
    ymethyl compound, racemic lacosamide, would not have
    been known, and Dr. Wang’s prediction of an ED50 was
    based only on impermissible hindsight. Similarly, Appel-
    lants’ position before the Board was that a person of skill
    in the art would replace the NH group with CH2, but RCT
    suggests that the FAA literature consistently showed that
    removing the amino in the α-carbon amino substituents
    reduced potency.
    We agree with RCT that the Board’s findings are sup-
    ported by substantial evidence. Even if a person of skill
    in the art would have been motivated to modify compound
    3l, the record evidence suggests that compounds without a
    methoxyamino or nitrogen-containing group at the α-
    carbon had reduced activity. For example, compound 3a
    in Kohn 1991, with an amine group at the α-carbon,
    reported an ED50 of 65.1 mg/kg, whereas compound 2a,
    with a methyl group at that position, was less potent with
    an ED50 of 76.5 mg/kg. J.A. 2405. Likewise, compounds
    3a, 3b, and 3c, with ED50 values of 65.1 mg/kg, 44.5
    mg/kg, and 42.4 mg/kg, each have a nitrogen-containing
    moiety at the α-carbon. Id. These compounds were more
    potent than their oxygen-containing analogs, compounds
    3r, 3s, and 3t, with ED50 values of 80.1 mg/kg, 98.3 mg/kg,
    and 62.0 mg/kg, respectively. Id.
    The evidence also suggests that replacing the meth-
    oxyamino in compound 3l would have yielded a different
    MYLAN PHARMACEUTICALS INC. v. RESEARCH CORPORATION        17
    TECHS., INC.
    conformation. Such a conformational change may have
    affected interaction with receptors and altered biological
    activity. J.A. 11113–14. Kohn 1991 itself explains that
    “stringent steric and electronic requirements exist for
    maximal anticonvulsant activity,” J.A. 2404, which would
    counsel against modifying compound 3l in a way that
    would change its conformation significantly.
    Appellants fault the Board for crediting the testimony
    of Dr. Roush, RCT’s expert, regarding the three-
    dimensional structures of compound 3l and racemic
    lacosamide. The Board, however, provided a sufficient
    rationale for relying on Dr. Roush’s testimony that the
    three-dimensional structures of compound 3l and racemic
    lacosamide would be “very different.” Decision, 
    2017 WL 1096590
    , at *10. Specifically, the Board compared Dr.
    Roush’s testimony to that of Dr. Heathcock, who agreed
    that a molecule’s shape and potency may differ upon
    substitution of carbon for nitrogen. 
    Id.
     at *10–11. The
    Board was well within its discretion to credit Dr. Roush’s
    testimony. See Yorkey v. Diab, 
    601 F.3d 1279
    , 1284 (Fed.
    Cir. 2010) (“[T]he Board was well within its discretion to
    give more credibility to [one expert’s] testimony over
    [another expert’s testimony] unless no reasonable trier of
    fact could have done so.”).
    The Board also was entitled to reject bioisosterism as
    a basis for a motivation to modify compound 3l. While
    Silverman does disclose that that bioisosterism may be
    useful to attenuate toxicity in a lead compound, the record
    does not indicate why bioisosterism would have been used
    to modify compound 3l in particular, which already had a
    high potency and low toxicity, and why methylene was a
    natural isostere of methoxyamino.
    In light of the reductions in potency and the signifi-
    cant conformational changes that would have been ex-
    pected, the Board’s finding that a person of skill in the art
    would not have been motivated to modify the methoxy-
    18   MYLAN PHARMACEUTICALS INC. v. RESEARCH CORPORATION
    TECHS., INC.
    amino group in compound 3l was supported by substan-
    tial evidence.
    Because we agree with the Board that Appellants
    failed to establish a motivation to modify compound 3l, we
    need not reach Appellants’ arguments regarding objective
    indicia. Likewise, because we find that Appellants did not
    meet their burden to show that claims 1–9 would have
    been obvious over Kohn 1991 and Silverman, we conclude
    that the Board did not err in concluding that Appellants
    failed to meet their obviousness burden regarding claims
    10–13, which depend therefrom. Dependent claims, with
    added limitations, are generally not obvious when their
    parent claims are not. W.L. Gore & Assocs., Inc. v. Gar-
    lock, Inc., 
    721 F.2d 1540
    , 1555 (Fed. Cir. 1983).
    Aside from these factual issues, Appellants challenge
    aspects of the Board’s legal analysis, contending that the
    Board improperly required them to prove that the pro-
    posed modification would increase or maintain potency
    and that the Board negated their proposed motivation
    argument without making a finding that the prior art
    taught away from the proposed modification. None of
    these arguments has merit. Appellants’ arguments are
    merely an attack on factual findings under the guise of a
    challenge to the Board’s legal analysis. As discussed
    above, the Board appropriately considered all the facts
    before making a final obviousness determination.
    Having considered the record below, we conclude that
    the Board’s obviousness conclusion was supported by
    substantial evidence.
    Finally, at oral argument, Appellants requested in the
    alternative that the court remand this case in light of
    SAS Institute, Inc. v. Iancu, 
    138 S. Ct. 1348
     (2018). Oral
    Arg. at 27:05–27:17, http://oralarguments.cafc.uscourts.go
    v/default.aspx?fl=2017-2088.mp3. We decline to do so.
    MYLAN PHARMACEUTICALS INC. v. RESEARCH CORPORATION       19
    TECHS., INC.
    We have held that a party’s request for SAS relief can
    be waived. PGS Geophysical AS v. Iancu, 
    891 F.3d 1354
    ,
    1362–63 (Fed. Cir. 2018). In cases where a litigant lodges
    a prompt request for SAS-based relief, however, this court
    has found waiver inapplicable and remanded to the Board
    to consider noninstituted grounds. See, e.g., Adidas AG v.
    Nike, Inc., 
    894 F.3d 1256
    , 1258 (Fed. Cir. 2018); Polaris
    Indus. Inc. v. Arctic Cat, Inc., 724 F. App’x 948, 950 (Fed.
    Cir. 2018) (per curiam); South-Tek Sys., LLC v. Engi-
    neered Corrosion Sols., LLC, No. 2017-2297, 
    2018 WL 4520013
    , at *5 (Fed. Cir. Sept. 20, 2018); Baker Hughes
    Oilfield Operations, LLC v. Smith Int’l, Inc., No. 2018-
    1754, 
    2018 WL 4087705
    , at *2 (Fed. Cir. May 30, 2018).
    Here, Appellants’ request—made over 6 months after
    the SAS decision—was not prompt. To be sure, the
    Supreme Court’s SAS decision issued after the briefing
    was complete in this case. But Appellants had opportuni-
    ties to raise the SAS issue with the court before oral
    argument (i.e., in a citation of supplemental authority as
    authorized by Fed. Cir. R. 28(j)) and chose not to do so.
    Indeed, Appellants could have raised their SAS argument
    even in their opening oral argument. Instead, they chose
    to raise it in their rebuttal argument—when RCT had no
    meaningful opportunity to respond. Given the circum-
    stances in this case, we find that Appellants have waived
    their request for remand. Cf. Becton Dickinson & Co. v.
    C.R. Bard, Inc., 
    922 F.2d 792
    , 800 (Fed. Cir. 1990) (stat-
    ing that the court’s “sound practice” of finding arguments
    absent from opening briefs to be waived “may as a matter
    of discretion not be adhered to where circumstances
    indicate that it would result in basically unfair proce-
    dure”).
    CONCLUSION
    In sum, we affirm the Board’s conclusion that Appel-
    lants have failed to show that claims 8–13 would have
    been obvious at the time of the invention. We have con-
    20   MYLAN PHARMACEUTICALS INC. v. RESEARCH CORPORATION
    TECHS., INC.
    sidered RCT’s remaining arguments and find them un-
    persuasive.
    For the foregoing reasons, we affirm the decision of
    the Board.
    AFFIRMED