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 Trademark 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-
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ceutical, Inc.

 TODD S. WERNER, Carlson, Caspers, Vandenburgh, 

Lindquist & Schuman, PA, Minneapolis, MN, for appellant Alembic Pharmaceuticals Ltd. Also represented by 

SARAH STENSLAND, Patterson Thuente Pedersen, PA, 

Minneapolis, MN. 

 JACK B. BLUMENFELD, Morris, Nichols, Arsht & Tunnell 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, “Appellants”) 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 conditions affecting the structure of the brain, but, for the vast 
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3

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.
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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 compounds 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 reexamination 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).
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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 19912 and Silverman3 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 compound 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 moieties and acetylated amino groups provided potent protection 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 compound 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 Anticonvulsant Activity of a Series of Functionalized α-HeteroatomSubstituted 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. 
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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 concluded 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 αcarbon position. J.A. 2405. Its structure is as follows:

To supply a motivation to modify compound 3l, Argentum relied on Silverman, a book chapter on drug discovery, 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 
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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 instituted 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 activity “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 rational 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 exhibiting 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 persuaded 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.
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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 petition, 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 Argentum 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-cv01214-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).
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ceutical compounds and (2) that the methoxyamino moiety may present synthetic and stability problems. According 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] arguendo, that an ordinary artisan would have selected compound 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 methoxyamino moiety to confer significant activity to the compound 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 bioisosterism 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 toxicity.” 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-
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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 dependent claims, the Board declined to consider Petitioners’ 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 Appellants have standing to make this appeal. RCT does not 
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assert that Appellants lack Article III standing. Appellee’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, Appellants 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 exercised 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 “statutory scheme here . . . does not authorize Appellants to seek 

federal court review of the Board’s [final written] decision.” 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 principles of statutory interpretation, asking not “whether in 
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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, Appellants’ participation should not be “transformed into a 

right to federal court review.” Appellee’s Br. 19–20. But 
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§ 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 support for the proposition that a party subject to such restrictions 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 nonobviousness conclusion. Regarding claims 1–9, Appellants assert a lead compound analysis, proposing 

compound 3l in Kohn 1991 as the lead. In its final written decision, the Board did not resolve whether compound 

3l was an appropriate lead compound. Instead, it accepted 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 whether compound 3l would have been a suitable lead compound. 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 
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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, synthetically 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 pharmaceutically 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,’ including the size of the group on the α-carbon.” Id. at 24 (quoting Kohn 1991, J.A. 2407). According to Appellants, their

proposed replacement retained a small moiety at the αcarbon, which would have satisfied steric requirements 

and would have left the N-benzylamide moiety and acetylated amino group unchanged. Appellants also argue 

that, consistent with Kohn 1991, their proposed modification retained a functionalized oxygen atom two atoms 

removed from the α-carbon atom, which Kohn 1991 disclosed as associated with excellent potency.

Appellants further contend that their proposed modification 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 
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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 methoxy 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 available reference compounds, including phenytoin, phenobarbital, 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 familiarity 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 because 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
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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 methoxymethyl compound, racemic lacosamide, would not have 

been known, and Dr. Wang’s prediction of an ED50 was

based only on impermissible hindsight. Similarly, Appellants’ 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 supported 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 αcarbon 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 methoxyamino in compound 3l would have yielded a different 
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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 threedimensional 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 significant conformational changes that would have been expected, the Board’s finding that a person of skill in the art

would not have been motivated to modify the methoxy-
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amino group in compound 3l was supported by substantial 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. Garlock, 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 proposed 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

TECHS., INC. 

19

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. Engineered 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 opportunities 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 circumstances 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) (stating 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 procedure”).

CONCLUSION

In sum, we affirm the Board’s conclusion that Appellants have failed to show that claims 8–13 would have 

been obvious at the time of the invention. We have con-
MYLAN PHARMACEUTICALS INC. v. RESEARCH CORPORATION

TECHS., INC. 20

sidered RCT’s remaining arguments and find them unpersuasive.

For the foregoing reasons, we affirm the decision of 

the Board.

AFFIRMED