NOTE: This disposition is nonprecedential.

 

United States Court of Appeals 

for the Federal Circuit ______________________ 

IN RE: IKEDA FOOD RESEARCH CO., LTD.,

Appellant

______________________ 

2017-2624

______________________ 

Appeal from the United States Patent and Trademark 

Office, Patent Trial and Appeal Board in No. 12/851,668.

______________________ 

Decided: January 29, 2019

______________________ 

THOMAS H. JENKINS, Finnegan, Henderson, Farabow, 

Garrett & Dunner, LLP, Washington, DC, argued for 

appellant. Also represented by MICHAEL PAUL BARKER,

MICHAEL LIU SU, Palo Alto, CA. 

 SARAH E. CRAVEN, Office of the Solicitor, United 

States Patent and Trademark Office, Alexandria, VA, 

argued for appellee Andrei Iancu. Also represented by

THOMAS W. KRAUSE, KAKOLI CAPRIHAN. 

 ______________________ 

Before WALLACH, TARANTO, and HUGHES, Circuit Judges.

WALLACH, Circuit Judge. 

Appellant Ikeda Food Research Co., Ltd. (“Ikeda”) appeals a decision on appeal of the U.S. Patent and Trade-
2 IN RE: IKEDA FOOD RESEARCH CO., LTD. 

mark Office’s (“USPTO”) Patent Trial and Appeal Board 

(“PTAB”) in an ex parte reexamination affirming an 

examiner’s rejection of, inter alia, claims 22−23 (“the 

Challenged Claims”) of U.S. Patent Application No. 

12/851,668 (“the ’668 application”) (J.A. 837–99) as obvious pursuant to 35 U.S.C. § 103(a) (2006).1 See In re 

Ikeda Food Research Co., No. 2015-002637 (P.T.A.B. July 

28, 2017) (J.A. 2–17). We have jurisdiction pursuant to 28 

U.S.C. § 1295(a)(4)(A) (2012). We affirm.

BACKGROUND

I. The ’668 Application

Entitled “Coenzyme-Binding Glucose Dehydrogenase,”

the ’668 application generally relates to a “convenient” 

method for patients to regularly measure and monitor 

their blood glucose, i.e., blood sugar, “and a means for 

controlling the blood sugar level . . . which can be utilized 

not only in a hospital but also at home.” J.A. 839. The 

enzymatic method employs blood glucose “biosensors,”2

 

1 Congress amended § 103 when it enacted the 

Leahy-Smith America Invents Act (“AIA”). Pub. L. No. 

112-29, § 3(c), 125 Stat. 284, 287 (2011). However, because the ’668 application never contained a claim having 

an effective filing date on or after March 16, 2013 (the 

effective date of the statutory changes enacted in 2011), or 

a reference under 35 U.S.C. §§ 120, 121, or 365(c) to any 

patent or application that ever contained such a claim, 

the pre-AIA § 103 applies. See id. § 3(n)(1), 125 Stat. at 

293. 

2 Biosensors commonly rely on enzymes, with the 

most commonly used enzymes being those that catalyze 

(cause or accelerate) oxidation-reduction reactions. See 

J.A. 356. Such enzymes include glucose oxidases (“GOx”) 

and glucose dehydrogenases (“GDH”), the latter of which 

includes enzymes that use nicotinamide adenine dinucleo-
IN RE: IKEDA FOOD RESEARCH CO., LTD. 3

J.A. 839, as “an important marker for diabetes,” J.A. 838. 

The ’668 application describes prior art methods that use 

“a biosensor employing a [GDH]” and exhibit various 

disadvantages, such as “high background noise” that 

leads to erratic readings “due to a level of residual oxygen,” and “a complicated reaction system” that is “expensive.” J.A. 839–40. The ’668 application purports to 

improve upon the prior art by claiming use of, inter alia, a 

specific enzyme: a “flavin”-dependent GDH (“FAD-GDH”) 

designated as Enzyme Commission (“E.C.”)3 1.1.99.10,

J.A. 890, whose “relative reactivity” (or “substrate specificity”), was found to exhibit “high activity” on glucose, 

and “low activity” on the seventeen other substrates 

tested, including maltose, see J.A. 864−65. 

The “objective of the invention is to provide a novel 

[GDH] which exhibits an excellent substrate-recognizing 

ability toward glucose and which has low activity on 

maltose,[4] and also to provide a method for producing the 

same and a microorganism having an ability of producing 

the same.” J.A. 841. The newly-discovered “coenzymebinding [GDH] has [the] ability of catalyzing a reaction 

for oxidizing glucose, especially a hydroxyl group in the 

 

tide (“NAD(P)+”) or pyrroloquinoline quinone (“PQQ”) as 

an expensive and unstable cofactors. See J.A. 356, 

838−40, 843. 

3 E.C. numbers are promulgated by the Enzyme 

Commission, J.A. 176, and provide a common classification scheme for enzymes based on the chemical reactions 

they catalyze, see J.A. 7−8. 

4 Maltose is “a sugar produced by the breakdown of 

starch,” and enzymes that have intrinsic enzymatic 

activity towards maltose, such as PQQ-GDH, were later 

reported to pose high risks for patients on infusion drugs. 

J.A. 269; see J.A. 840−41 (excerpts from another utility 

patent application).
4 IN RE: IKEDA FOOD RESEARCH CO., LTD. 

[first] position of glucose, in the presence of an electron 

acceptor.” J.A. 842. To obtain the FAD-GDH enzyme, a 

microorganism (or microbe) containing the enzyme is first

“cultured,” and the enzyme is “recovered from the culture 

by means of an ordinary protein purification method.” 

J.A. 864, 869. The ’668 application recounts the purified 

enzyme’s activity to maltose as 1.4%, relative to its activity to glucose, which is regarded as 100%. See J.A. 882

(Table 1); see also J.A. 845 (describing the graphical data 

quantifying various activity of the coenzyme-binding 

GDHs). Accordingly, the purified FAD-GDH enzyme is

used in prior-art biosensors that comprise “an action 

electrode, a counter electrode,” and “an enzymatic reaction layer.” J.A. 874. 

Independent claim 22 is representative of the Challenged Claims, and recites: 

A biosensor for measuring glucose, comprising:

an electrode system comprising an action 

electrode and a counter electrode; and

an enzymatic reaction layer in contact 

with the action electrode and/or the counter electrode, the enzymatic reaction layer 

comprising an electron acceptor and a soluble [f]lavin compound-binding glucose 

dehydrogenase, which has enzymatic activity to glucose comprising catalyzing a 

reaction for oxidizing glucose in the presence of the electron acceptor,

wherein enzymatic activity to maltose in 

the enzymatic reaction layer is 5% or less 

relative to the enzymatic activity to glucose; 

wherein the biosensor can quantify glucose concentrations ranging from 4.5 mM 

to 30 mM. 
IN RE: IKEDA FOOD RESEARCH CO., LTD. 5

J.A. 230 (emphasis added).

II. The Prior Art References

A. Senior 

Entitled “Method for Determining Glucose Content of 

Fluid,” European Patent Application Publication 

No. 0094161 (“Senior”) (J.A. 283−300) discloses a qualitative procedure for determining blood glucose concentration, preferably using either a FAD-GDH enzyme derived 

from a strain of A. orzyae, which is a different microorganism than the ’668 application’s FAD-GDH enzyme yet 

similarly designated E.C. 1.1.99.10, or a PQQ-GDH 

enzyme which is designated E.C. 1.1.99.17. See J.A. 283 

(“A method for determining glucose present in a fluid 

wherein a sample of a glucose-containing fluid is contacted with an assay mixture comprising . . . flavin-dependent 

glucose dehydrogenase enzyme E.C. 1.1.99.10 and a 

reducible compound, reduction of which can produce

changes in electro-magnetic radiation absorbance characteristics and/or electrical changes.”), 287 (discussing “a 

preferred source of E.C. 1.1.99.17” as the second enzyme). 

Senior states that the FAD-GDH enzyme it employs “need

not be purified to an excessively high standard” and that 

the PQQ-GDH has some “lesser activity on other sugars.” 

J.A. 289.

B. The Yugawa Patents

Related U.S. Patent Nos. 6,656,702 (“Yugawa A”) and 

6,059,946 (“Yugawa B”) (collectively, “the Yugawa patents”) disclose “a biosensor” comprising, inter alia, an 

“electrode system” with a “working electrode,” “counter 

electrode,” and “a reaction layer.” Yugawa A col. 2 ll. 3−7; 

see Yugawa B col. 2 ll. 4−8 (same). The enzymes used in 

the reaction layer specifically include GDH and PQQGDH. Yugawa A col. 2 ll. 8−15; Yugawa B col. 5 l. 45. 

The Yugawa patents also describe stability and cost 

advantages of their biosensor similar to those described in 
6 IN RE: IKEDA FOOD RESEARCH CO., LTD. 

the ’668 application. Compare Yugawa A col. 1 l. 63–col. 2 

l. 2, and Yugawa B col. 1 ll. 66−67, with J.A. 840–41.

DISCUSSION

I. Standard of Review and Legal Standard

“We review the PTAB’s factual findings for substantial evidence and its legal conclusions de novo.” Redline 

Detection, LLC v. Star Envirotech, Inc., 811 F.3d 435, 449 

(Fed. Cir. 2015) (citation omitted). “Substantial evidence 

is something less than the weight of the evidence but 

more than a mere scintilla of evidence,” meaning that “[i]t 

is such relevant evidence as a reasonable mind might 

accept as adequate to support a conclusion.” In re NuVasive, Inc., 842 F.3d 1376, 1379–80 (Fed. Cir. 2016) (internal quotation marks and citations omitted). “If two 

inconsistent conclusions may reasonably be drawn from 

the evidence in record, the PTAB’s decision to favor one 

conclusion over the other is the epitome of a decision that 

must be sustained upon review for substantial evidence.” 

Elbit Sys. of Am., LLC v. Thales Visionix, Inc., 881 F.3d 

1354, 1357 (Fed. Cir. 2018) (internal quotation marks, 

brackets, and citation omitted).

A patent claim is invalid “if the differences between 

the subject matter sought to be patented and the prior art 

are such that the subject matter as a whole would have 

been obvious at the time the invention was made to a 

person having ordinary skill in the art [(‘PHOSITA’)].” 35 

U.S.C. § 103(a). Obviousness is a question of law based 

on underlying findings of fact. See In re Adler, 723 F.3d 

1322, 1325 (Fed. Cir. 2013). Those underlying findings of 

fact include: (1) “the scope and content of the prior art,” 

(2) “differences between the prior art and the claims at 

issue,” (3) “the level of ordinary skill in the pertinent art,” 

and (4) the presence of objective indicia of nonobviousness, such “as commercial success, long felt but unsolved 

needs, failure of others,” and unexpected results. Graham 

v. John Deere Co. of Kan. City, 383 U.S. 1, 17 (1966); see 
IN RE: IKEDA FOOD RESEARCH CO., LTD. 7

United States v. Adams, 383 U.S. 49, 50–52 (1966). For 

objective indicia of non-obviousness, a showing that a 

problem was both recognized in the prior art and there 

existed a failure of others to provide “a feasible solution to 

the long-standing problem” supports a finding of long-felt 

need. In re Cyclobenzaprine Hydrochloride, 676 F.3d

1063, 1083 (Fed. Cir. 2012) (citation omitted). Further, 

“[a]n obviousness determination requires finding that a 

[PHOSITA] would have been motivated to combine or 

modify the teachings in the prior art and would have had 

a reasonable expectation of success in doing so.” Regents 

of Univ. of Cal. v. Broad Inst., Inc., 903 F.3d 1286, 1291

(Fed. Cir. 2018) (citation omitted). 

“We have recognized that inherency may supply a 

missing claim limitation in an obviousness analysis.” 

PAR Pharm., Inc. v. TWI Pharm., Inc., 773 F.3d 1186, 

1194–95 (Fed. Cir. 2014); see id. at 1195 (collecting cases). 

However, “the limitation at issue necessarily must be 

present[] or the natural result of the combination of 

elements explicitly disclosed by the prior art” to be inherently disclosed by the reference. Id.; see Southwire Co. v. 

Cerro Wire LLC, 870 F.3d 1306, 1311 (Fed. Cir. 2017)

(requiring the PTAB to find that a reference disclosed an 

“identical or substantially identical” process to that 

claimed by the patent in order to find inherent obviousness). Where “all process limitations . . . are expressly 

disclosed by [the prior art reference], except for the functionally expressed [limitation at issue], the [US]PTO can 

require an applicant to prove that the subject matter 

shown to be in the prior art does not possess the characteristic relied on.” Southwire, 870 F.3d at 1311 (internal 

quotation marks and citation omitted).

II. Obviousness

The PTAB affirmed the Examiner’s findings that employing the FAD-GDH enzyme preparation described in 

Senior with the biosensor described in the Yugawa pa-
8 IN RE: IKEDA FOOD RESEARCH CO., LTD. 

tents would have rendered the Challenged Claims obvious 

to a PHOSITA. See J.A. 9−10; see also J.A. 153−57 (Examiner’s findings). In rendering its obviousness decision, 

the PTAB specifically determined that even though Senior 

did not expressly disclose the low-maltose activity limitation of claim 22 of the ’668 application, Senior’s disclosed 

enzyme preparation inherently contains the same enzymatic specificity for glucose relative to maltose as the 

Challenged Claims. See J.A. 10; see also J.A. 10−11 

(relying on the undisputed fact that both Senior and the

’668 application classify their respective FAD-GDH enzyme in their enzyme preparations as E.C. 1.1.99.10, and 

concluding that it was reasonable to infer they have the 

same low substrate specificity for glucose relative to 

maltose). The PTAB also disagreed with Ikeda that 

Ikeda’s proffered extrinsic evidence of another “contaminated” GDH preparation somehow established that Senior’s enzyme preparation was likewise contaminated. J.A. 

11−12. Ikeda contends that “the PTAB erred in its prima 

facie case” by (1) relying upon inherency to supply the 

necessary low-maltose activity claim element in making 

its obviousness determination, see Appellant’s Br. 30, and

(2) improperly shifting the evidentiary burden to Ikeda, 

see id. at 33. Ikeda also asserts that “the [PTAB] erred in 

discounting the objective indicia of nonobviousness,” 

especially that of a long-felt need. Id. at 42 (capitalization 

modified). We address each argument in turn.

A. Substantial Evidence Supports the PTAB’s Determination that the Challenged Claims Would Have Been Obvious over Senior and the Yugawa Patents

Ikeda contests the PTAB’s determination that Senior’s E.C. 1.1.99.10 FAD-GDH enzyme preparation inherently discloses the Challenged Claims’ limitation of a 

reaction layer with low reactivity toward maltose relative 

to glucose, id. at 30, but does not contest that each of the 
IN RE: IKEDA FOOD RESEARCH CO., LTD. 9

other limitations are taught by this combination, see 

generally id.5 Specifically, Ikeda argues that because 

“Senior’s enzyme preparation was contaminated with 

about 7,000 times more protein than the [’668 application]’s preparation,” these impurities cause Senior’s 

preparation to “differ[] vastly” from the ’668 application’s 

preparation in how it reacts with maltose. Appellant’s Br.

31. We disagree.

Substantial evidence supports the PTAB’s conclusion 

that Senior’s FAD-GDH enzyme preparation inherently 

discloses the Challenged Claims’ low-maltose activity 

limitation. Table 1 of the ’668 application discloses that 

the E.C. 1.1.99.10 enzyme’s activity for maltose is 1.4%

relative to its activity for glucose. See J.A. 882 (reporting

testing results in Table 1 that state that the FAD-GDH 

enzyme preparation’s activity towards “maltose” is “1.4%” 

relative to its 100% activity towards glucose). Senior 

discloses an assay for determining blood glucose concentration and teaches, in relevant part, purifying an FADGDH enzyme from a crude cellular extract. See J.A. 287. 

Although Senior does not directly address glucose specificity or maltose, see J.A. 283−300, Senior’s FAD-GDH 

enzyme, prepared from “A[.] oryzae,” has the same “E.C. 

1.1.99.10” classification number as the ’668 application’s 

FAD-GDH enzyme, even though each FAD-GDH enzyme 

is produced from a different microorganism, i.e., from “A. 

terreus,” compare J.A. 287, 293, with J.A. 843. E.C. 

classification numbers are based on enzyme reactivity, see

J.A. 176 (describing, in a scientific journal, the known 

 

5 Ikeda also does not dispute the PTAB’s finding 

that the Yugawa patents’ biosensor (comprising “an 

insulating plate (layer), electrode system, and a reaction 

layer,” J.A. 9), could be combined with Senior’s FAD-GDH 

E.C. 1.1.99.10 enzyme to arrive at the Challenged Claims’ 

biosensor, see generally Appellant’s Br. 
10 IN RE: IKEDA FOOD RESEARCH CO., LTD. 

“genomics” and “chemical information” represented by 

E.C. classification numbers), and Ikeda’s counsel does not 

dispute that enzymes with the same E.C. number have the 

same substrate specificity “for purposes of this appeal,”

Oral. Arg. at 6:32−:47, http://oralarguments.cafc.uscourts.

gov/default.aspx?fl=2017-2624.mp3. Therefore, it was

reasonable for the PTAB to conclude that both Senior and 

the ’668 application characterize their microbe-derived 

preparations as having identical enzymatic activity, which

necessarily includes having the same substrate specificity. 

See J.A. 7−8, 11; cf. Butamax (TM) Advanced Biofuels 

LLC v. Gevo, Inc., 746 F.3d 1302, 1306 (Fed. Cir. 2014)

(acknowledging that assignment “of different E[.]C[.]

numbers to the same enzyme” indicates that “the difference between the numbers is the identity of the cofactor 

named”), judgment vacated sub nom. on other grounds

Gevo, Inc. v. Butamax Advanced Biofuels LLC, 135 S. Ct. 

1173 (2015). The PTAB had a reasonable basis to conclude that because Senior discloses the use of the FADGDH enzyme described in the ’668 application, classified 

under E.C. 1.1.99.10, the claimed low “5% or less” activity

against maltose relative to glucose in the reaction layer is

inherently disclosed in Senior’s enzyme preparation. See

J.A. 11; see also PAR Pharm., 773 F.3d at 1194–95 (concluding that “[t]he claimed . . . parameters . . . [were] 

inherent properties of the obvious . . . formulation,” and 

thus “[t]he reduced food effect was an inherent result of [a 

composition] even if it was previously not known in the 

prior art that a food effect existed” (internal quotation 

marks and citation omitted)).

The PTAB properly adhered to our precedent regarding the prima facie framework to conclude that Ikeda 

failed to present sufficient evidence to rebut the substantial evidence supporting that Senior’s FAD-GDH enzyme 

preparation inherently discloses the ’668 application’s 

claimed low maltose activity relative to glucose. See In re 

Spada, 911 F.2d 705, 708 (Fed. Cir. 1990) (“[W]hen the 
IN RE: IKEDA FOOD RESEARCH CO., LTD. 11

[US]PTO shows sound basis for believing that the products of the applicant and the prior art are the same, the 

applicant has the burden of showing that they are not.”

(emphasis added) (citation omitted)). Ikeda did not present evidence of testing any of the enzyme preparations 

found in the prior art, such as by replicating Senior’s 

described process of creating its preparation, to support 

its argument that the purity of Senior’s preparation must 

have differed from the ’668 application because it contained maltose hydrolyzing contaminants (or impurities). 

See J.A. 110−25 (Reply Brief), J.A. 249−447 (Reply to 

Final Action). Instead, Ikeda presented evidence in the 

form of U.S. Patent No. 7,655,130 (“Tsuji”) in support of 

its contention that because Tsuji’s purified FAD-GDH 

E.C. 1.1.99.10 enzyme preparation “AOGDH”6 has high 

maltose reactivity even after purification, there must 

likewise be maltose-hydrolyzing contaminants in Senior’s 

FAD-GDH preparation that would cause the preparation 

to exhibit more than 5% activity toward maltose relative 

to glucose. See J.A. 110−25 (Ikeda Reply Brief); see also 

J.A. 432 (stating, in Tsuji’s Example 1, that “[i]n the

AOGDH purified preparation, . . . 90% of maltose was 

already degraded into glucose, and after reacting for ten 

minutes, nearly 100% maltose was degraded”).7 The 

 

6 Tsuji refers to its GDH enzyme preparation as 

“AOGDH” because it is recovered from native fungus 

Aspergillus oryzae. See J.A. 431. 

7 The parties do not dispute that Tsuji, J.A. 426−48, 

which issued in 2010, qualifies as extrinsic evidence that 

may be relevant in determining what was inherently 

present in the prior art. See generally Appellant’s Br.; 

Appellee’s Br. Therefore, we deem it appropriate to 

consider Tsuji’s teachings here. See ASM Am., Inc. v. 

Genus, Inc., 401 F.3d 1340, 1347 (Fed. Cir. 2005) (concluding that extrinsic evidence that post-dated the patent 

filing date nonetheless was helpful in determining how a 
12 IN RE: IKEDA FOOD RESEARCH CO., LTD. 

PTAB found that “Tsuji’s example of a contaminated 

preparation [did not] establish the presence of such contaminants in Senior.” J.A. 11. In addition, there is no 

specific evidence in Tsuji or of record that any contaminant in Tsuji results in a greater than 5% maltose activity 

relative to glucose. See Tsuji col. 1 l. 28−col. 14 l. 8. To 

the contrary, Tsuji’s AOGDH preparation Table 1 shows 

low, i.e., “0.4%,” enzymatic reactivity to maltose relative 

to “100.0%” reactivity to glucose. Id. col. 12 ll. 1−43. The 

PTAB could reasonably find that Tsuji does not persuasively rebut the prima facie finding of inherency.

Moreover, simply because Senior never quantified 

maltose activity achieved by its disclosed embodiments 

does not preclude the PTAB’s evidentiary finding that 

Senior’s enzyme preparation process necessarily achieved 

the low activity of 5% or less relative to glucose claimed in 

the Challenged Claims, see J.A. 230; J.A. 11−12, especially since Senior’s enzyme’s stated E.C. classification was 

the same as the ’668 application’s enzyme, compare J.A. 

293 with J.A. 843. “In the absence of any evidence that 

the claimed [low activity] would have been unexpected in 

light of [Senior’s] disclosure, there is no indication that 

the limitation is anything other than mere quantification 

of the results of a known process.” Southwire, 870 F.3d at

1311. As our predecessor court explained, the fairness of 

shifting the burden “is evidenced by the [US]PTO’s inability to manufacture products or to obtain and compare

prior art products.” In re Best, 562 F.2d 1252, 1255

(CCPA 1997). Therefore, we see no reason to call into 

question the PTAB’s finding “that the ‘possible presence 

of contaminants’ in Senior’s enzyme preparation [does 

not] render the claimed biosensor non-obvious.” J.A. 11;

see Elbit, 881 F.3d at 1537 (“If two inconsistent conclu-

 

PHOSITA would have understood the claim term at the 

time it was filed).
IN RE: IKEDA FOOD RESEARCH CO., LTD. 13

sions may reasonably be drawn from the evidence in 

record, the PTAB’s decision to favor one conclusion over 

the other is the epitome of a decision that must be sustained upon review for substantial evidence.” (internal 

quotation marks and citation omitted)). Ikeda’s evidence 

does not show that the PTAB lacked a reasonable basis 

for finding that Senior, as the operative prior art, necessarily possesses the ’668 application’s claimed low maltose 

activity relative to glucose. See In re Spada, 911 F.2d at 

709 (determining that an appellant “showed no error, in 

science or in law, in the [PTAB]’s holding that . . . the 

products [at issue] appeared to be the same and thus that 

[the appellant’s] products were not new”). 

Ikeda’s counterarguments lack merit. First, Ikeda argues that the PTAB improperly “conflat[ed] Senior’s 

enzyme preparation with the enzyme per se,” Appellant’s 

Br. 30, such that the E.C. 1.1.99.10 “designation does not 

mean that the enzyme preparation possesses only that 

single enzymatic activity,” id. at 32. However, Ikeda’s 

logic misses the mark. The Challenged Claims do not 

require such exclusivity; the only disputed limitation is 

that they require a low maltose relative to glucose. See

J.A. 230. Thus, Ikeda’s contention that an E.C. designation does not refer to a single enzymatic activity does not 

contradict the evidence supporting the PTAB’s finding 

that the E.C. 1.1.99.10 designation means that the preparation has identical or similar substrate specificity for 

glucose. 

Second, Ikeda avers that the PTAB “ignored [Ikeda]’s 

evidence when deciding whether there exists a reasonable 

basis for inherency.” Appellant’s Br. 36 (emphasis added). 

However, as we determine above, the PTAB expressly 

considered, and found unpersuasive, Ikeda’s evidence in

support of its argument that the purity of Senior’s enzyme 

preparation differed from the ’668 application and thus 

did not inherently possess low activity against maltose. 

See, e.g., J.A. 11 (stating that, “[a]s an initial matter, 
14 IN RE: IKEDA FOOD RESEARCH CO., LTD. 

[Ikeda’s] speculation about the possibility that Senior’s 

preparation may contain contaminants does not establish 

that Senior’s preparation in fact had such contaminants,” 

and that while the PTAB “agree[d] with [Ikeda] that the 

claims are directed to the activity of the enzyme layer and 

not just of GDH,” it “d[id] not agree that the ‘possible 

presence of contaminants’ in Senior’s enzyme preparation 

renders the claimed biosensor non-obvious” (emphases 

added)), 12 (“[Ikeda’s] example relied on a different preparation method than was used in Senior.”). Accordingly, 

the PTAB properly considered the record evidence in 

affirming the Examiner’s obviousness findings. 

B. Substantial Evidence Supports the PTAB’s Finding

that Objective Indicia of Nonobviousness Do Not Rebut 

the Prima Facie Case of Obviousness

The PTAB found, inter alia, that Ikeda’s “objective indicia of nonobviousness” do not “demonstrate[] the nonobviousness of the claimed biosensor” because the “scope 

of the [Challenged] Claims was not commensurate with 

the asserted need.” J.A. 15. The PTAB accorded Ikeda’s 

expert’s testimony little weight when he testified that 

“biosensors based on NAD-GDH enzymes did not satisfy 

this long-felt need because they require a cofactor” because the Challenged Claims “encompass biosensors that 

use cofactors and thus do not satisfy the alleged need for 

dehydrogenase-based glucose sensors that do not rely on a 

cofactor.” J.A. 15. Ikeda argues that “a need existed since 

at least 1986 for improved blood glucose monitors” that 

were “both specific and independent of separate cofactors.” Appellant’s Br. 43, 44 (capitalization modified). 

Ikeda also argues that the PTAB “erred by not crediting 

[Ikeda’s] evidence of long-felt need” for a GDH enzyme 

with no separate cofactor. Id. at 47. We disagree with 

Ikeda.

We see no error in the PTAB’s analysis, and ultimate 

rejection as unpersuasive, of Ikeda’s evidence of secondary 
IN RE: IKEDA FOOD RESEARCH CO., LTD. 15

considerations relating to long-felt need. Ikeda’s expert 

stated that twenty years elapsed after the publication of 

Senior, and seventeen years elapsed after a 1986 publication by Ikeda’s expert documenting a “need for a dehydrogenase-based glucose sensor” that “ha[d] no cofactor 

requirement,” before the ’668 application was filed. 

J.A. 273−74 (expert declaration); see J.A. 14 (acknowledging, by the PTAB, that “[a]lthough Senior does not require 

a cofactor, [Ikeda’s expert] contends that Senior’s disclosure failed to satisfy the need for a dehydrogenase-based 

glucose sensor because of the possible presence of contaminants and the low degree of purification” (internal quotation marks and citation omitted)). However, the PTAB

considered Ikeda’s expert testimony and concluded that it 

did not have any substantive relevance, see J.A. 14−15, a 

determination that we do not revisit, see Elbit, 881 F.3d 

at 1358 (“The PTAB is entitled to weigh the credibility of 

the witnesses.” (brackets and citation omitted)). Furthermore, we recognize that claim 22 employs the transitional phrase “comprising” in the preamble, J.A. 230, and, 

therefore, does not exclude biosensors that employ a 

cofactor, see CIAS, Inc. v. All. Gaming Corp., 504 F.3d 

1356, 1360 (Fed. Cir. 2007) (“In the patent claim context[,] 

the term ‘comprising’ is well understood to mean ‘including but not limited to.’” (citation omitted)). Thus, the 

Challenged Claims encompass biosensors that use cofactors, and it follows that they do not satisfy Ikeda’s alleged 

need for dehydrogenase-based glucose sensors that do not 

rely on a cofactor.8

 

8 The PTAB found, as an alternative to its inherent 

obviousness analysis, that even if “Senior’s [FAD-GDH] 

enzyme preparation includes contaminants, it would have 

been obvious for [a PHOSITA] to modify . . . Senior’s 

chromatographic purification to” achieve the claimed lowmaltose activity of the ’668 application’s FAD-GDH en-
16 IN RE: IKEDA FOOD RESEARCH CO., LTD. 

CONCLUSION

We have considered Ikeda’s remaining arguments and 

find them unpersuasive. Accordingly, the Decision on 

Appeal of the U.S. Patent and Trademark Office’s Patent 

Trial and Appeal Board is

AFFIRMED

 

zyme. J.A. 12 (emphasis added) (internal quotation 

marks and citation omitted). Although Ikeda challenges 

this alternative finding on appeal, see Appellant’s Br. 5, 

39−41, we need not address this alternative theory, given 

that we uphold the PTAB’s inherent obviousness determination, see supra Section II.B; In re Gleave, 560 F.3d 

1331, 1338 (Fed. Cir. 2009) (declining to address alternative grounds of unpatentability when we uphold one such 

ground).