In Re Cyclobenzaprine Hydrochloride Extended-Release Capsule Patent Litigation ( 2012 )


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  •    United States Court of Appeals
    for the Federal Circuit
    __________________________
    IN RE CYCLOBENZAPRINE HYDROCHLORIDE
    EXTENDED-RELEASE CAPSULE PATENT
    LITIGATION
    ---------------------------------------------------------------------------------
    ------------------------------------
    EURAND, INC. (NOW KNOWN AS APTALIS
    PHARMATECH, INC.), CEPHALON, INC., AND
    ANESTA AG,
    Plaintiffs-Cross Appellants,
    v.
    MYLAN PHARMACEUTICALS INC. AND MYLAN
    INC.,
    Defendants-Appellants,
    and
    PAR PHARMACEUTICAL, INC.,
    Defendant-Appellee.
    __________________________
    2011-1399, -1409
    __________________________
    Appeals from the United States District Court for the
    District of Delaware in Case No. 09-MD-2118, Judge Sue
    L. Robinson.
    _____________________
    Decided: April 16, 2012
    _____________________
    EURAND   v. MYLAN                                           2
    JONATHAN E. SINGER Fish & Richardson, P.C., of Wil-
    mington, Delaware, argued for plaintiff-cross appellant.
    With him on the brief were WILLIAM J. MARSDEN, JR. of
    Minneapolis, Minnesota, JUANITA R. BROOKS, of San
    Diego, California, and CHERYLYN ESOY MIZZO, of Wash-
    ington, DC.
    JAMES H. WALLACE, JR., Wiley Rein LLP, of Washing-
    ton, DC, argued defendants-appellants. With him on the
    brief were MARK A. PACELLA, ROBERT J. SCHEFFEL,
    MATTHEW J. DOWD, KEVIN P. ANDERSON and BRIAN H.
    PANDYA.
    __________________________
    Before NEWMAN, O’MALLEY, and REYNA, Circuit Judges.
    O’MALLEY, Circuit Judge.
    After a bench trial, the U.S. District Court for the Dis-
    trict of Delaware found U.S. Patent Nos. 7,387,793 and
    7,544,372 invalid as obvious. Case No. 2011-1409 is an
    appeal from that judgment. We reverse and vacate the
    district court’s judgment of invalidity because the district
    court erred when it declared the patents in suit invalid as
    obvious. Specifically, by failing to consider the lack of a
    known pharmacokinetic/pharmacodynamic relationship
    for the claimed drug formulation, the trial court erred
    when it assessed the importance of the teachings of the
    prior art to the obviousness analysis.
    As an alternative ground in support of the district
    court’s judgment invalidating the ’793 and ’372 patents,
    the defendants argue that the district court erred when it
    found that the patents satisfy the best mode disclosure
    requirement. We affirm the district court’s best mode
    ruling. The evidence supports a finding that the patents
    3                                         EURAND   v. MYLAN
    in suit enable one of ordinary skill in the art to practice
    the inventor’s preferred dew points.
    After invalidating the ’793 and ’372 patents as obvi-
    ous, the district court enjoined the defendants—the
    parties who prevailed at trial—from launching their
    generic product pending appeal to this court. That order
    is challenged in Case No. 2011-1399. We dismiss that
    appeal as premature because several outstanding issues
    in the district court leave uncertain whether the defen-
    dants could recover on their appeal bond.
    I.
    Plaintiff Aptalis Pharmatech, Inc. is the owner of the
    ’793 and ’372 patents. Plaintiff Anesta AG, a wholly
    owned subsidiary of plaintiff Cephalon, Inc., is the exclu-
    sive licensee of the patents. We refer to the plaintiffs
    collectively as Cephalon.
    The ’793 patent covers a modified-release dosage form
    of skeletal muscle relaxants. The ’372 patent covers a
    method of relieving muscle spasms with the formulation
    disclosed in the ’793 patent. Cephalon markets a drug
    covered by the patents under the brand name Amrix. The
    active pharmaceutical ingredient in Amrix is cycloben-
    zaprine hydrochloride. A single dose of Amrix releases
    cyclobenzaprine hydrochloride in the body during a
    twenty-four-hour period.       Immediate-release formula-
    tions, by contrast, release the drug in a shorter amount of
    time and require multiple daily doses.
    The ’793 and ’372 patents share the same specifica-
    tion and, as relevant to this appeal, have the same limita-
    tions in claims 1–3. Claim 1 recites a dosage form of a
    skeletal muscle relaxant (in the ’793 patent) and a
    method of relieving muscle spasms (in the ’372 patent),
    which, in relevant part, “provides [a] therapeutically
    EURAND   v. MYLAN                                           4
    effective plasma concentration over a period of 24 hours to
    treat muscle spasm associated with painful musculoskele-
    tal conditions . . . .” ’793 patent col.10 ll.23, 43–46 (filed
    Nov. 14, 2003); ’372 patent col.10 ll.21, 43–46 (filed Feb. 6,
    2008). Claim 2 depends on claim 1 and specifies the
    claimed skeletal muscle relaxant as cyclobenzaprine
    hydrochloride. ’793 patent col.10 ll.62–64; ’372 patent
    col.10 ll.61–62. Claim 3 depends on claim 2 and specifies
    the following pharmacokinetic values:
    [A] maximum blood plasma concentration
    (Cmax) within the range of about 80% to
    125% of about 20 ng/mL of cycloben-
    zaprine HCl and an AUC0–168 within the
    range of about 80% to 125% of about 740
    ng·hr/mL and a Tmax within the range of
    80% to 125% of about 7 hours following
    oral administration . . . .
    ’793 patent col.10 l.65–col.11 l.5; ’372 patent col.10 l.63–
    col.11 l.3.
    Pharmacokinetics is the study of what a person’s body
    does to a drug after administration. The pharmacokinetic
    (“PK”) values recited in claim 3 measure various charac-
    teristics about the drug’s behavior in a patient’s blood
    plasma. Cmax, as claim 3 alludes, represents the maxi-
    mum concentration of the drug in a person’s blood
    plasma. AUC0–168 represents the area under the blood
    plasma concentration curve, or, in other words, the body’s
    total exposure to the drug. Tmax represents the time after
    administration when the maximum concentration of the
    drug in the blood plasma (Cmax) occurs.
    To formulate a therapeutically effective, extended-
    release version of cyclobenzaprine hydrochloride, the
    inventors had to ascertain the correct pharmacoki-
    netic/pharmacodynamic (“PK/PD”) profile. The PK side of
    5                                         EURAND   v. MYLAN
    the relationship—what a person’s body does to the drug—
    includes the Cmax, AUC, and Tmax, as identified in claim 3.
    The PD side of the relationship describes the effect that a
    drug renders on a person’s body. The PD of cycloben-
    zaprine hydrochloride is the relief of muscle spasms.
    The determination of a PK profile is a quantitative
    exercise. The determination of PD, or therapeutic effec-
    tiveness, however, is a qualitative exercise. As one of
    Cephalon’s experts, Dr. Stanley Davis, explained, a
    therapeutically effective plasma concentration is “a con-
    centration that the formulation provides when the formu-
    lation works.” The district court, likewise, construed the
    claim limitation “therapeutically effective plasma concen-
    tration” to mean “the amount of a drug required to pro-
    duce the therapeutic result.”
    One of the patents’ inventors, Dr. Gopi Venkatesh,
    testified at trial about how he and his co-inventor, Dr.
    James Clevenger, ascertained the correct PK/PD profile
    for the patented formulation. First, they estimated PK
    values with computer models. They started by creating
    PK profiles for the immediate-release formulation. The
    immediate-release formulation is dosed at 10 mg. Using
    immediate-release PK data, the inventors created models
    for twice-a-day dosing and three-times-a-day dosing at 10
    mg per dose. Then, they drew on that data to create a
    model for a single, 30 mg dose. The inventors then cre-
    ated an in vitro dissolution profile, which modeled how
    much drug would be released over time if the formulation
    with the model PK values were placed in a solution such
    as water. Finally, the inventors tested a formulation with
    the model PK values and dissolution profile in a clinic.
    Clinical test results confirmed that the formulation was
    therapeutically effective.
    EURAND   v. MYLAN                                         6
    II.
    The defendants, Mylan Pharmaceuticals Inc. and My-
    lan Inc. (collectively, “Mylan”), and Par Pharmaceutical,
    Inc. (“Par”), filed abbreviated new drug applications
    (“ANDAs”) for generic versions of extended-release
    cyclobenzaprine hydrochloride. In support of their AN-
    DAs, Mylan and Par filed “Paragraph IV” certifications, in
    which they alleged that their generic products would not
    infringe the ’793 patent, or that the patent was invalid or
    unenforceable. See 
    21 U.S.C. § 355
    (j)(2)(A)(vii)(IV) (2006).
    The U.S. Food and Drug Administration (“FDA”) ap-
    proved both defendants’ applications. Because Mylan was
    the first party to file a Paragraph IV certification, the
    FDA granted Mylan a 180-day exclusive marketing period
    for its generic product.
    Cephalon sued Mylan and Par for patent infringe-
    ment, claiming that the defendants’ filing of their ANDAs
    infringed the ’793 patent. See 
    35 U.S.C. § 271
    (e)(2) (2006
    & Supp. IV 2010). The FDA stayed Mylan’s exclusive
    marketing period for thirty months because of the litiga-
    tion. The district court conducted a bench trial in Sep-
    tember and October 2010. Rather than ruling from the
    bench, the district court took the matter under advise-
    ment to prepare a written opinion. The end of the FDA’s
    thirty-month stay approached as the parties waited for
    the district court’s opinion. On April 8, 2011, the district
    court, sua sponte, temporarily enjoined Mylan from
    launching its generic product pending the issuance of an
    opinion. The thirty-month stay expired on April 17, 2011.
    The district court issued its written opinion on May
    12, 2011. It ruled that Mylan’s and Par’s products in-
    fringed the ’793 and ’372 patents, but that Cephalon’s
    asserted patent claims were invalid as obvious. The
    district court entered judgment of invalidity in favor of
    7                                         EURAND   v. MYLAN
    Mylan and Par. The district court’s sua sponte injunction
    expired by its own terms upon entry of judgment.
    On May 13, 2011, the day after the district court en-
    tered judgment, Mylan launched its generic product. On
    May 15, 2011, Cephalon moved for an injunction to bar
    Mylan’s launch pending appeal and to recapture product
    already released. Cephalon argued that it was likely to
    prevail on appeal because it believed the district court
    had made a number of errors in its obviousness analysis.
    In response, the district court conceded certain errors and
    modified some of its findings, but reaffirmed its obvious-
    ness ruling. Notwithstanding that it affirmed Mylan’s
    victory, the district court granted Cephalon’s motion for
    injunctive relief and issued an injunction pending appeal
    to this court. The district court expressed uncertainty
    about whether this court would affirm its invalidity ruling
    and found that Cephalon was “just as likely as not” to
    succeed on appeal. The district court then found that the
    potential harm to Cephalon and a lack of a corresponding
    threat of harm to Mylan weighed in favor of an injunction.
    Mylan appealed the injunction. Cephalon appealed
    the district court’s invalidity ruling. Mylan moved this
    court to stay the injunction pending resolution of the
    appeal, and this court did so temporarily, pending full
    briefing of Mylan’s motion. In re Cyclobenzaprine Hydro-
    chloride Extended-Release Capsule Patent Litig., No.
    2011-1399 (Fed. Cir. May 25, 2011) (order granting im-
    mediate stay of preliminary injunction). After briefing
    from the parties, this court lifted the temporary stay, but
    declined to require that Mylan recall any product it had
    sold while the stay was in place. In re Cyclobenzaprine
    Hydrochloride Extended-Release Capsule Patent Litig.,
    Nos. 2011-1399, 2011-1409 (Fed. Cir. July 7, 2011) (order
    granting temporary stay in part). We now consider both
    appeals on their merits.
    EURAND   v. MYLAN                                          8
    III.
    We address the district court’s obviousness ruling
    first. A patent may not issue “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 to which said
    subject matter pertains.” 
    35 U.S.C. § 103
    (a) (2006).
    Obviousness is a question of law based on underlying
    factual findings: (1) the scope and content of the prior art;
    (2) the differences between the claims and the prior art;
    (3) the level of ordinary skill in the art; and (4) objective
    considerations of nonobviousness. Graham v. John Deere
    Co., 
    383 U.S. 1
    , 17–18 (1966). Generally, a party seeking
    to invalidate a patent as obvious must “demonstrate ‘by
    clear and convincing evidence that a skilled artisan would
    have had reason to combine the teaching of the prior art
    references to achieve the claimed invention, and that the
    skilled artisan would have had a reasonable expectation
    of success from doing so.’” Procter & Gamble Co. v. Teva
    Pharms. USA, Inc., 
    566 F.3d 989
    , 994 (Fed. Cir. 2009)
    (quoting Pfizer, Inc. v. Apotex, Inc., 
    480 F.3d 1348
    , 1361
    (Fed. Cir. 2007)). See also Amgen, Inc. v. F. Hoffmann-La
    Roche Ltd., 
    580 F.3d 1340
    , 1362 (Fed. Cir. 2009) (“An
    obviousness determination requires that a skilled artisan
    would have perceived a reasonable expectation of success
    in making the invention in light of the prior art.”) (cita-
    tions omitted). The Supreme Court has warned, however,
    that, while an analysis of any teaching, suggestion, or
    motivation to combine known elements is useful to an
    obviousness analysis, the overall obviousness inquiry
    must be expansive and flexible. KSR Int’l Co. v. Teleflex,
    Inc., 
    550 U.S. 398
    , 415, 419 (2007).
    In reviewing a district court’s obviousness ruling after
    a bench trial, we review its legal conclusion de novo, but
    9                                          EURAND   v. MYLAN
    we review its underlying factual findings for clear error.
    Proctor & Gamble, 
    566 F.3d at
    993–94. The clear-error
    standard of review applied to a district court’s factual
    findings demands that we defer to those findings unless
    we are left with “a definite and firm conviction that a
    mistake has been committed.” United States v. U.S.
    Gypsum Co., 
    333 U.S. 364
    , 395 (1948). While we afford
    deference to a district court’s factual findings, however,
    we retain plenary review to determine whether, as a legal
    matter, the evidence satisfies the clear-and-convincing
    standard of proof. Proctor & Gamble, 
    566 F.3d at
    993–
    94. Indeed, the Supreme Court recently confirmed that a
    party asserting an obviousness claim bears that high
    burden of persuasion. Microsoft Corp. v. i4i Ltd., 
    131 S. Ct. 2238
    , 2242 (2011).
    A.
    We find that the district court’s legal conclusion that
    bioequivalence alone was sufficient to render the claims
    at issue obvious was in error. We also find clear error in a
    number of the district court’s factual findings, as identi-
    fied below.
    The obviousness inquiry in this case is focused on bio-
    equivalence. The concept of bioequivalence means the
    body is exposed to the same amount of active pharmaceu-
    tical ingredient at the same rate after administration of
    either an immediate-release or extended-release formula-
    tion. The district court found the asserted claims obvious
    because it believed the claimed extended-release PK
    profile is bioequivalent to the immediate-release PK
    profile. Mylan agrees with the district court’s approach of
    resting its obviousness finding on bioequivalence. Cepha-
    lon, however, argues that the district court placed undue
    weight on bioequivalence and, as a result, misinterpreted
    the proffered prior art references.
    EURAND   v. MYLAN                                       10
    We agree with Cephalon. The district court treated
    bioequivalence as the end of its inquiry when the court
    found that it would have been obvious to a person having
    ordinary skill in the art to target extended-release PK
    values “mirroring”—in other words, bioequivalent to—
    those of the immediate-release cyclobenzaprine formula-
    tion. The district court, however, was also required to
    consider the asserted claims’ limitation requiring thera-
    peutic effectiveness, and whether it would have been
    obvious to one of ordinary skill in the art at the time of
    the invention that a bioequivalent PK value would satisfy
    that limitation. Graham, 
    383 U.S. at
    17–18 (making clear
    that “differences between the prior art and the claims at
    issue are to be ascertained”) (emphasis added).
    Mylan and Par argued, and the district court agreed,
    that the undisputed fact that cyclobenzaprine lacked a
    known PK/PD relationship at the time of invention was
    irrelevant. Without such a known relationship, however,
    skilled artisans could not predict whether any particular
    PK profile, including a bioequivalent one, would produce a
    therapeutically effective formulation. Dr. Davis, Cepha-
    lon’s expert, testified that cyclobenzaprine’s “mode of
    action was not really well known and there [was] cer-
    tainly no clear relationship between a given pharmacoki-
    netic profile and the pharmacodynamic effect, what it
    actually does to the body.” One of the defendants’ experts,
    Dr. Gordon Amidon, acknowledged that there was nothing
    in the prior art or published literature “that would help a
    person skilled in the art determine a therapeutically
    effective plasma concentration over a 24-hour period.”
    Mylan and Par did not dispute that cyclobenzaprine
    lacked a known PK/PD relationship. Rather, they at-
    tempted to avoid that fact in two ways. First, they as-
    serted the truism that skilled artisans would need only a
    reasonable expectation of success and would not need to
    11                                         EURAND   v. MYLAN
    be certain of what a particular PK profile would yield.
    See Defs.’ Resp. & Reply Br. 26. Second, Mylan and Par
    argued to the district court that the patents in suit lack
    sufficient written description to support the “therapeuti-
    cally effective” limitation. Lack of written description,
    however, is a separate defense, which the defendants do
    not advance on appeal. For purposes of obviousness,
    therefore, we must accept as true that cyclobenzaprine
    lacked a known PK/PD relationship at the time of inven-
    tion, and that the asserted claims contain a valid “thera-
    peutically effective” limitation.
    The district court misapprehended the importance of
    the lack of a known PK/PD relationship. The district
    court stated that “[t]he lack of a PK/PD relationship is of
    no moment . . . given that one of ordinary skill in the art
    would expect the extended release formulation to have the
    same PD effect on the body if it has the immediate release
    formulation’s PK profile.” That statement contains an
    inherent contradiction. By stating that skilled artisans
    would assume that the immediate-release and extended-
    release PK profiles produce the same PD effect, the dis-
    trict court was assuming that a known PK/PD relation-
    ship existed for the immediate-release formulation.
    Because all experts and parties agree, however, that
    skilled artisans did not know the PK/PD relationship even
    for the immediate-release formulation, there was no way
    to match the dosage for the extended-release formulation
    to achieve a known therapeutic effect. The district court,
    therefore, could not find obviousness without finding that
    the prior art would have taught or suggested a therapeu-
    tically effective formulation to one of ordinary skill in the
    art. The record lacks any such evidence. While it may
    have been obvious to experiment with the use of the same
    PK profile when contemplating an extended-release
    formulation, there is nothing to indicate that a skilled
    EURAND   v. MYLAN                                        12
    artisan would have had a reasonable expectation that
    such an experiment would succeed in being therapeuti-
    cally effective. See Proctor & Gamble, 
    566 F.3d at 994
    (requiring a reasonable expectation of success to prove
    obviousness).
    This distinction is important. Where a skilled artisan
    merely pursues “known options” from “a finite number of
    identified, predictable solutions,” the resulting invention
    is obvious under Section 103. KSR, 
    550 U.S. at 421
    .
    Where, however, a defendant urges an obviousness find-
    ing by “merely throw[ing] metaphorical darts at a board”
    in hopes of arriving at a successful result, but “the prior
    art gave either no indication of which parameters were
    critical or no direction as to which of many possible
    choices is likely to be successful,” courts should reject
    “hindsight claims of obviousness.” In re Kubin, 
    561 F.3d 1351
    , 1359 (Fed. Cir. 2009) (quoting In re O’Farrell, 
    853 F.2d 894
    , 903 (Fed. Cir. 1988)).
    B.
    The district court’s failure to appreciate the lack of a
    known PK/PD relationship for any formulation of
    cyclobenzaprine rendered deficient its analysis of the
    evidence that Mylan and Par offered to prove the claimed
    PK values obvious and its analysis of the implications of
    that evidence on its legal conclusion of obviousness. We
    explain below why the district court’s analysis was defi-
    cient.
    1.
    The district court found that a skilled artisan could
    calculate the claimed AUC and Tmax by conducting what it
    called “routine experimentation”: creating computer
    models based on data from articles by Winchell and
    Hucker, and PK data for Flexeril, the branded immediate-
    13                                         EURAND   v. MYLAN
    release formulation. The district court relied on the
    testimony of Dr. Amidon in interpreting those prior art
    references. 1 Mylan and Par agree with the district court,
    arguing that the evidence shows that “one of ordinary
    skill in the art could readily convert the known pharma-
    cokinetic data for Flexeril® administered 10 mg three
    times a day to an equivalent pharmacokinetic profile for a
    single daily 30 mg administration.” Defs.’ Resp. & Reply
    Br. 40.
    Dr. Amidon’s testimony, however, was insufficient to
    support the conclusion that a skilled artisan would rea-
    sonably expect to achieve a therapeutically effective AUC
    and Tmax. Indeed, it was actually inconsistent with that
    conclusion. As Dr. Amidon explained, Winchell reveals
    that cyclobenzaprine is linear, which means that blood
    plasma concentration increases proportionally to dosage.
    The fact that a skilled artisan could have predicted a
    particular blood plasma concentration, however, does not
    mean that such knowledge would have provided a skilled
    artisan a reasonable expectation of success in calculating
    a blood plasma concentration that was therapeutically
    effective. As Dr. Amidon also explained, Winchell sug-
    gests that cyclobenzaprine is well absorbed in the body.
    That information, however, pertains to the body’s physical
    absorption of the drug rather than the correct PK/PD
    relationship. As Dr. Amidon further explained, Winchell
    provides PK values for immediate-release cycloben-
    1   The district court also relied upon the testimony
    of another defense expert, Dr. Courtney Fletcher, to find
    that the Tmax can be calculated when the other parame-
    ters of the model are known. Because Cephalon is correct
    that Dr. Fletcher was not qualified to testify to that point,
    any reliance on Dr. Fletcher for this proposition was clear
    error. Indeed, the district court seemed to concede this
    point when responding to the errors that Cephalon identi-
    fied in the court’s trial opinion.
    EURAND   v. MYLAN                                       14
    zaprine, and Hucker provides plasma concentration time
    curves for the immediate-release formulation. Without a
    known PK/PD relationship, however, immediate-release
    PK values are of little use in calculating extended-release
    values, because there is no proof that a skilled artisan
    would expect the extended-release values to produce a
    therapeutic effect solely because they are drawn from
    immediate-release values.
    The evidence on which the district court relied to find
    the claimed Cmax obvious similarly focuses on bare PK
    values rather than the PD effect that the PK values could
    be expected to produce. The district court found that
    Winchell “undisputably [sic]” disclosed the claimed Cmax.
    Winchell indicates that, after subjects are dosed every
    eight hours for seven days at 10 mg/dose, subjects have a
    Cmax of 25.9 ng/ml. That value is 129.5% of 20 ng/ml.
    Claim 3 of the patents in suit claims a Cmax range of about
    80% to 125% of about 20 ng/ml. The district court, how-
    ever, cited no evidence specifically indicating that a
    cyclobenzaprine PK profile with a Cmax of 129.5% of 20
    ng/ml would be expected to yield the same therapeutic
    effect as that with a Cmax range of about 80% to 125% of
    about 20 ng/ml.
    The district court, moreover, cited nothing to support
    a finding that the claimed Cmax range of about 80% to
    125% of about 20 ng/ml even encompasses Winchell’s Cmax
    of 129.5% of 20 ng/ml. Claim 3 does specify that the
    claimed range is about 80% to 125% of about 20 ng/ml.
    The district court construed the term “about” to mean
    “approximately,” but failed to cite any evidence indicating
    that 129.5% of 20 ng/ml is approximately 125% of 20
    15                                        EURAND   v. MYLAN
    ng/ml.     The parties have not directed us to any such
    proof. 2
    The district court found persuasive Dr. Amidon’s ul-
    timate opinion that a skilled artisan could expect to
    achieve efficacy by relying on the Winchell and Hucker
    articles to estimate a PK profile for an extended-release
    formulation by using computer software. While we would
    normally afford the district court deference in crediting
    such an opinion, we cannot do so here because Dr. Amidon
    failed to discuss why, in the specific context of cycloben-
    zaprine, a skilled artisan would expect PK values drawn
    from the prior art to yield a therapeutically effective
    formulation. Indeed, the portion of Dr. Amidon’s testi-
    mony on which the district court relied conflicts with his
    acknowledgement that the prior art and published litera-
    ture lacked any guidance to help a skilled artisan deter-
    mine a therapeutically effective, extended-release plasma
    concentration. Dr. Amidon’s own computer modeling,
    moreover, failed to generate PK values within the claimed
    ranges.
    Mylan and Par rely extensively on Dr. Amidon’s tes-
    timony about the prior art in arguing that it would have
    been obvious to try to develop extended-release cycloben-
    2  While it might appear to a layperson that 129.5%
    is “about” 125%, expert testimony is necessary to estab-
    lish how a person having ordinary skill in the art would
    perceive those figures. We have no way of knowing the
    importance of even small differences in these percentages
    in the absence of some evidence in the record addressing
    that point. See Ortho-McNeil Pharm., Inc. v. Caraco
    Pharm. Labs., Inc., 
    476 F.3d 1321
    , 1326 (Fed. Cir. 2007)
    (“The use of the word “about,” avoids a strict numerical
    boundary to the specified parameter. Its range must be
    interpreted in its technological and stylistic context.”
    (quoting Pall Corp. v. Micron Separations, Inc., 
    66 F.3d 1211
    , 1217 (Fed. Cir. 1995))).
    EURAND   v. MYLAN                                       16
    zaprine bioequivalent to the immediate-release PK pro-
    file, and that skilled artisans would have had a reason-
    able expectation of success in doing so. The insufficiency
    of that evidence demonstrates why the defendants’ argu-
    ment stands on a weak foundation. Evidence of obvious-
    ness, especially when that evidence is proffered in support
    of an “obvious-to-try” theory, is insufficient unless it
    indicates that the possible options skilled artisans would
    have encountered were “finite,” “small,” or “easily trav-
    ersed,” and that skilled artisans would have had a reason
    to select the route that produced the claimed invention.
    Ortho-McNeil Pharm., Inc. v. Mylan Labs., Inc., 
    520 F.3d 1358
    , 1364 (Fed. Cir. 2008) (citing KSR, 
    550 U.S. at 421
    ).
    While it is true that Section 103 bars patentability unless
    “the improvement is more than the predictable use of
    prior art elements according to their established func-
    tions,” KSR, 
    550 U.S. at 417
    , where the prior art, at best,
    “[gives] only general guidance as to the particular form of
    the claimed invention or how to achieve it,” relying on an
    “obvious-to-try” theory to support an obviousness finding
    is “impermissible.” In re Kubin, 
    561 F.3d at 1359
     (quoting
    In re O’Farrell, 
    853 F.2d at 903
    ). Nothing in Dr. Amidon’s
    testimony sheds light on why a skilled artisan would have
    chosen a bioequivalent PK profile in the absence of a
    known PK/PD relationship for cyclobenzaprine. Thus, the
    absence of such testimony suggests that skilled artisans
    would not have encountered finite, small, or easily trav-
    ersed options in developing a therapeutically effective,
    extended-release formulation. See 
    id.
     And, there is
    nothing in the record to support the conclusion that what
    the co-inventors did here was no more than a “predictable
    use of known prior art elements.” KSR, 
    550 U.S. at 417
    .
    The Winchell and Hucker articles, the Flexeril data,
    and the defense experts’ interpretation of those refer-
    ences, fail to indicate that a skilled artisan would have
    17                                         EURAND   v. MYLAN
    reasonably expected to calculate therapeutically effective
    PK values based on those references. While the district
    court’s assessment of this evidence may be understand-
    able given its predicate mistake regarding the absence of
    a known PK/PD profile for the immediate-release formu-
    lation, it was, nonetheless, clear error.
    2.
    The district court also relied on other evidence to sup-
    port its obviousness analysis. The district court’s factual
    conclusions from this evidence again were clearly errone-
    ous, however, and the weight given to them in the court’s
    obviousness conclusion was undue.
    The district court noted that Dr. Clevenger, co-
    inventor of the patents in suit, created computer models
    of the claimed PK values after he reviewed the Flexeril
    PK data. The district court cited Dr. Clevenger’s ap-
    proach when it concluded that the claimed AUC and Tmax
    could be obtained by “routine experimentation.” In rely-
    ing on Dr. Clevenger’s testimony, the district court merely
    retraced the inventor’s steps. This hindsight analysis is
    inappropriate because obviousness must be assessed at
    the time the invention was made. See Ortho-McNeil, 
    520 F.3d at 1364
     (noting that 
    35 U.S.C. § 103
    (a) directs an
    inquiry into whether the subject matter as a whole “would
    have been obvious at the time the invention was made”).
    Like the district court, Mylan and Par rely on Dr.
    Clevenger’s testimony for the proposition that “one of
    ordinary skill could use the available software . . . and
    estimate the parameters identified by Mylan’s experts.”
    Defs.’ Resp. & Reply Br. 41. Like the district court,
    however, Mylan and Par employ hindsight analysis.
    Dr. Clevenger’s testimony, moreover, does not support
    the proposition for which the district court cited it. The
    district court found significant Dr. Clevenger’s testimony
    EURAND   v. MYLAN                                         18
    that “[i]t can be assumed that the [immediate-release
    product] produced a therapeutic effect . . .” and that “if we
    get something similar to those blood levels . . . then we,
    too, will have a product that will produce a therapeutic
    effect.” The district court, however, omitted the next
    exchange in Dr. Clevenger’s examination: “[Question:] . . .
    So the idea is that if the blood levels were similar to
    Flexeril, then hopefully, the effect would be similar—the
    therapeutic effect would be similar to Flexeril? [Answer:]
    Hopefully. Depends on the relationship between blood
    levels and therapeutic effect.” The district court later
    attempted to minimize the importance of Dr. Clevenger’s
    omitted testimony, concluding that “this testimony simply
    shows that the inventor needed to verify his results in the
    lab. Obviousness calls for an expectation of success, not a
    guarantee.” A plain reading of the testimony, however,
    indicates that Dr. Clevenger never expressed even an
    expectation of success. He merely testified that, whether
    blood levels similar to those produced by Flexeril would
    produce a therapeutic effect similar to that of Flexeril,
    depended on the relationship between blood levels and
    therapeutic effectiveness—a relationship that all concede
    was unknown.
    The district court also relied on an FDA guidance
    document, which it found directed skilled artisans to
    pursue bioequivalence when formulating extended-release
    formulations. The title of the document the district court
    cited is “Guidance for Industry.” The district court found
    that the document sets forth an FDA directive that an
    extended-release dosage form have the same AUC and
    Cmax of an already-approved immediate-release formula-
    tion. The FDA document, however, states that its pur-
    pose is “to provide recommendations to sponsors and/or
    applicants planning to include . . . bioequivalence infor-
    mation” in applications. The document provides advice on
    19                                         EURAND   v. MYLAN
    what they should do if they plan to pursue bioequivalence.
    The document provides little support for an obviousness
    finding here, because, in the absence of a known PK/PD
    relationship for cyclobenzaprine, there is no evidence that
    a skilled artisan would have targeted bioequivalence in
    the first instance.
    One judge of our court has observed that the FDA’s
    publishing of approval requirements for extended-release
    formulations does not necessarily render obvious a drug
    that meets those requirements, because “knowledge of the
    goal does not render its achievement obvious.” Abbott
    Labs., Inc. v. Sandoz, Inc., 
    544 F.3d 1341
    , 1352 (Fed. Cir.
    2009). That observation is particularly salient here
    because Mylan and Par fail to demonstrate that skilled
    artisans would have even viewed bioequivalence as the
    goal when creating an extended-release cyclobenzaprine
    formulation. Indeed, while there might have been a
    desire for an extended-release formulation, there is no
    evidence that skilled artisans would have known how to
    achieve it. See Cardiac Pacemakers, Inc. v. St. Jude Med.,
    Inc., 
    381 F.3d 1371
    , 1377 (Fed. Cir. 2004) (“Recognition of
    a need does not render obvious the achievement that
    meets that need. . . . Recognition of an unsolved problem
    does not render the solution obvious.”).
    3.
    Finally, the district court relied on two other prior art
    references, neither of which supports a finding that the
    “therapeutically effective” limitation is obvious. Those
    references—
    U.S. Patent No. 6,344,215
     and European
    Patent Application No. 518,263A1 (“Urban”)—disclose
    formulation technology and dissolution profiles rather
    than pharmacokinetics. The Urban reference discloses a
    micropellet that can be used for an extended-release
    formulation. It lists cyclobenzaprine as a suitable me-
    EURAND   v. MYLAN                                        20
    dicament for the formulation. The ’215 patent—Dr.
    Venkatesh is the named inventor—discloses a multipar-
    ticulate dosage form, for use with methylphenidate, that
    features the same dissolution profile claimed in the pat-
    ents in suit. The district court believed that it would have
    been obvious to use the same drug delivery system be-
    cause it had already been proven effective with methyl-
    phenidate. Mylan and Par, likewise, argue that “[t]he
    only meaningful structural difference between the as-
    serted claims of the ’793 patent and ’215 patent was the
    active ingredient, cyclobenzaprine versus methylpheni-
    date.” Defs.’ Resp. & Reply Br. 8.
    Even if the ’215 patent and Urban teach the claimed
    physical drug delivery system and dissolution profile, they
    reveal nothing about the critical limitation at issue here:
    a therapeutically effective PK profile. Cephalon has
    acknowledged that the structure of the drug delivery
    system and the dissolution profile are not novel aspects of
    the claimed invention. Oral Argument at 22:40, available
    at            http://www.cafc.uscourts.gov/oral-argument-
    recordings/2011-1399/all. Urban and the ’215 patent
    provide no support for the district court’s obviousness
    finding with respect to pharmacokinetics.
    C.
    After the district court found that Mylan and Par
    proved the asserted claims obvious, it considered Cepha-
    lon’s proof of objective considerations of nonobviousness to
    determine whether Cephalon’s proofs were sufficient to
    “rebut” that obviousness determination. Specifically, the
    district court considered Cephalon’s evidence of the fail-
    ure of others to make the patented invention; longfelt but
    unsolved needs fulfilled by the patented invention; com-
    mercial success of the patented invention; and unexpected
    results produced by the patented invention. See Graham,
    21                                         EURAND   v. MYLAN
    
    383 U.S. at
    17–18; Pfizer, Inc. v. Apotex, Inc., 
    480 F.3d 1348
    , 1369 (Fed. Cir. 2007). The district court found
    Cephalon’s evidence insufficient to rebut Mylan’s and
    Par’s showing. The district court erred, however, by
    making its finding that the patents in suit were obvious
    before it considered the objective considerations and by
    shifting the burden of persuasion to Cephalon. In doing
    so, the district court contravened this court’s precedent
    requiring that a fact finder consider all evidence relating
    to obviousness before finding a patent invalid on those
    grounds, and the court imposed a burden-shifting frame-
    work in a context in which none exists.
    1.
    The premature nature of the court’s obviousness find-
    ing is apparent. Before it reached the objective considera-
    tions, the district court stated that the claimed PK profile
    “would have been obvious to one of skill in the art at the
    time of the invention” and that “a person of ordinary skill
    in the art would have been motivated to take a group of
    known elements to create an extended release version of
    cyclobenzaprine, and [would have had] a reasonable
    expectation of success in doing so.” It was not until after
    the district court found the asserted claims obvious that it
    proceeded to analyze the objective considerations, or what
    it called the “secondary considerations.”
    2.
    The district court’s error is understandable because
    this court has inconsistently articulated the burden of
    proof applicable to an obviousness defense in district court
    litigation. It was error nonetheless.
    In Stratoflex, Inc. v. Aeroquip Corp., we held that a
    fact finder in district court litigation may not defer ex-
    EURAND   v. MYLAN                                         22
    amination of the objective considerations until after the
    fact finder makes an obviousness finding:
    It is jurisprudentially inappropriate to
    disregard any relevant evidence on any is-
    sue in any case, patent cases included.
    Thus evidence rising out of the so-called
    “secondary considerations” must always
    when present be considered en route to a
    determination of obviousness. . . . Indeed,
    evidence of secondary considerations may
    often be the most probative and cogent
    evidence in the record. It may often estab-
    lish that an invention appearing to have
    been obvious in light of the prior art was
    not. It is to be considered as part of all the
    evidence, not just when the decisionmaker
    remains in doubt after reviewing the art.
    
    713 F.2d 1530
    , 1538–39 (Fed. Cir. 1983) (citations omit-
    ted). Many subsequent cases have expressly followed
    Stratoflex’s directive that courts consider all objective
    evidence before reaching an obviousness conclusion. See
    Ruiz v. A.B. Chance Co., 
    234 F.3d 654
    , 663 (Fed. Cir.
    2000) (“Our precedent clearly establishes that the district
    court must make Graham findings before invalidating a
    patent for obviousness.”); Cable Elec. Prods. v. Genmark,
    Inc., 
    770 F.2d 1015
    , 1026 (Fed. Cir. 1985) (quoting Strato-
    flex, 
    713 F.2d at 1539
    ) (“The opinions of this court have
    suggested that evidence on these secondary considera-
    tions is to be taken into account always, ‘not just when
    the decisionmaker remains in doubt after reviewing the
    art.’”); Simmons Fastener Corp. v. Illinois Tool Works,
    Inc., 
    739 F.2d 1573
    , 1575 (Fed. Cir. 1984); (“The section
    103 test of nonobviousness set forth in Graham is a four
    part inquiry comprising, not only the three familiar
    elements (scope and content of the prior art, differences
    23                                         EURAND   v. MYLAN
    between the prior art and the claims at issue, and level of
    ordinary skill in the pertinent art), but also evidence of
    secondary considerations when such evidence is, of course,
    present”); Richardson-Vicks Inc. v. Upjohn Co., 
    122 F.3d 1476
    , 1483 (Fed. Cir. 1997) (holding that “we must con-
    sider all of the evidence under the Graham factors before
    reaching our decision”); Rockwell Int’l Corp. v. United
    States, 
    147 F.3d 1358
    , 1366 (Fed. Cir. 1998) (following
    Richardson-Vicks); and Kan. Jack, Inc. v. Kuhn, 
    719 F.2d 1144
    , 1150–51 (Fed. Cir. 1983) (finding that a district
    court’s consideration of commercial success complied with
    “the basic requirement that all evidence touching the
    obvious-nonobvious issue be fully considered before a
    conclusion is reached on that issue” (citing In re Sernaker,
    
    702 F.2d 989
    , 996 (Fed. Cir. 1983))).
    While many panels of this court have adhered to Stra-
    toflex’s directive, some instead have spoken of the obvi-
    ousness analysis in terms of a “prima facie” case which
    must then be “rebutted” by the patentee. Under that
    framework, a court inquires whether the party challeng-
    ing validity has proven a “prima facie” case of obvious-
    ness, based only on reference to the patent and the
    proffered prior art, and only then considers objective
    evidence, asking whether such evidence is sufficient to
    overcome the prima facie case. 3
    3    See, e.g., Innovention Toys, L.L.C. v. MGA Entm’t,
    Inc., 
    637 F.3d 1314
    , 1323 (Fed. Cir. 2011) (“[S]hould the
    district court conclude [on remand] that [defendant] has
    made out a prima facie case of obviousness based on the
    [prior art], the court must then determine whether [plain-
    tiff’s] secondary considerations overcome [defendant’s]
    prima facie case”); Transocean Offshore Deepwater Drill-
    ing, Inc. v. Maersk Contractors USA, Inc., 
    617 F.3d 1296
    ,
    1305 (Fed. Cir. 2010) (“If all of the factual disputes re-
    garding the objective evidence resolve in favor of [plain-
    tiff], it has presented a strong basis for rebutting the
    EURAND   v. MYLAN                                        24
    Despite this language, however, those cases should
    not be interpreted as establishing a formal burden-
    shifting framework. This is so for a number of reasons.
    First, a review of those cases indicates that in none was
    the placement of the burden with respect to evidence of
    objective considerations, or the timing of the fact finder’s
    consideration of that evidence, determinative. See supra
    n.3.
    Second, even panels that have used the “prima facie”
    and “rebuttal” language generally have made clear that a
    fact finder must consider all evidence of obviousness and
    nonobviousness before reaching a determination. For
    example, in Iron Grip Barbell Co. v. USA Sports, Inc.,
    while the panel did hold that “there is no objective evi-
    dence to rebut the strong showing of obviousness based on
    prima facie case [of obviousness].”); Muniauction, Inc. v.
    Thomson Corp., 
    532 F.3d 1318
    , 1327 (Fed. Cir. 2008)
    (“Under the foregoing analysis, we conclude that [defen-
    dant] has clearly and convincingly established a prima
    facie case that claims 1 and 31 of the ’099 patent are
    obvious as a matter of law. Accordingly, we turn to
    [plaintiff’s] attempt to rebut this prima facie case with
    secondary considerations of nonobviousness.”); Eli Lilly &
    Co. v. Zenith Goldline Pharms., Inc., 
    471 F.3d 1369
    , 1380
    (Fed. Cir. 2006) (“[Plaintiff] overcame any prima facie
    case of obviousness . . . [because it] proved extensive
    secondary considerations to rebut obviousness”); Ormco
    Corp. v. Align Tech., Inc., 
    463 F.3d 1299
    , 1311 (Fed. Cir.
    2006) (“A nonmovant may rebut a prima facie showing of
    obviousness with objective indicia of nonobviousness.”);
    Iron Grip Barbell Co. v. USA Sports, Inc., 
    392 F.3d 1317
    ,
    1325 (Fed. Cir. 2004) (“[W]e conclude that there is no
    objective evidence to rebut the strong showing of obvious-
    ness based on the prior art.”); and WMS Gaming Inc. v.
    Int’l Game Tech., 
    184 F.3d 1339
    , 1359 (Fed. Cir. 1999)
    (“The objective evidence of non-obviousness may be used
    to rebut a prima facie case of obviousness based on prior
    art references.”).
    25                                         EURAND   v. MYLAN
    the prior art,” 
    392 F.3d 1317
    , 1325 (Fed. Cir. 2004), it also
    cautioned that, in “determining the question of obvious-
    ness, inquiry should always be made into whatever objec-
    tive evidence of nonobviousness there may be.” 
    Id. at 1323
     (quoting Vandenberg v. Dairy Equip. Co., 
    740 F.2d 1560
    , 1567 (Fed. Cir. 1984)). In Transocean Offshore
    Deepwater Drilling, Inc. v. Maersk Contractors USA, Inc.,
    while the panel observed that, “[i]f all of the factual
    disputes regarding the objective evidence resolve in favor
    of [plaintiff], it has presented a strong basis for rebutting
    the prima facie case [of obviousness],” the panel stated,
    “[t]o be clear, a district court must always consider any
    objective evidence of nonobviousness presented in a case.”
    
    617 F.3d 1296
    , 1305 (Fed. Cir. 2010). And in WMS Gam-
    ing Inc. v. International Game Technology, while the
    panel stated that “[t]he objective evidence of non-
    obviousness may be used to rebut a prima facie case of
    obviousness based on prior art references,” it also stated
    that “[t]he consideration of the objective evidence pre-
    sented by the patentee is a necessary part of the obvious-
    ness determination.” 
    184 F.3d 1339
    , 1359 (Fed. Cir.
    1999). Thus, a reading of these cases that permits a fact
    finder to reach a conclusion of obviousness before consid-
    ering all relevant evidence, including evidence of objective
    considerations, would not only conflict with Stratoflex’s
    directive that objective considerations are “to be consid-
    ered as part of all the evidence, not just when the deci-
    sionmaker remains in doubt after reviewing the art,” 
    713 F.2d at 1538
    , but would ignore their actual holdings.
    Next, the Supreme Court has never imposed nor even
    contemplated a formal burden-shifting framework in the
    patent litigation context. 4 It has, instead, required that
    4 The Court’s treatment of the burden of persuasion
    in the obviousness context markedly differs from its
    treatment of the burden of persuasion in other contexts,
    EURAND   v. MYLAN                                        26
    all evidence relevant to obviousness or nonobviousness be
    considered, and be considered collectively. In Graham,
    the Court stated that “[s]uch secondary considerations as
    commercial success, long felt but unsolved needs, failure
    of others, etc., might be utilized to give light to the cir-
    cumstances surrounding the origin of the subject matter
    sought to be patented,” along with the scope and content
    of the prior art, the differences between the prior art and
    the claims at issue, and the level of ordinary skill in the
    pertinent art. 
    383 U.S. at
    17–18. Notably, the Court did
    such as employment discrimination claims under Title VII
    of the Civil Rights Act of 1964. In McDonnell Douglas
    Corp. v. Green, the Court established the well-known
    formal, three-part burden-shifting framework that a
    plaintiff must satisfy to prove a discrimination claim with
    circumstantial evidence. 
    411 U.S. 792
     (1973). Several
    differences are apparent between the Court’s burden-
    shifting framework under McDonnell Douglas and its
    treatment of the burden of proof with respect to obvious-
    ness. First, the term “prima facie,” as used in the
    McDonnell Douglas context, means “the establishment of
    a legally mandatory, rebuttable presumption,” as opposed
    to “the plaintiff’s burden of producing enough evidence to
    permit the trier of fact to infer the fact at issue.” Tex.
    Dep’t of Cmty. Affairs v. Burdine, 
    450 U.S. 248
    , 254 n.7
    (1981). As discussed above, the Court has never spoken
    in terms of a legally rebuttable presumption with respect
    to obviousness. Second, the Court’s rationale for fashion-
    ing a formal burden-shifting framework in employment
    discrimination cases is to facilitate inquiry into an em-
    ployer’s intent: “the allocation of burdens and the creation
    of a presumption by the establishment of a prima facie
    case is intended progressively to sharpen the inquiry into
    the elusive factual question of intentional discrimination.”
    Burdine, 256 F.3d at 256 n.8. While the obviousness
    inquiry undoubtedly demands precision, the Court has
    never identified a problem in its application such that
    “sharpening” by way of a burden-shifting scheme is neces-
    sary.
    27                                         EURAND   v. MYLAN
    not characterize the objective factors as after-the-fact
    considerations or relegate them to “secondary status.”
    The Court, rather, indicated that the objective considera-
    tions have broader applicability, noting that, “[a]s indicia
    of obviousness or nonobviousness, these inquiries may
    have relevancy.” Id. The Court recently reaffirmed this
    approach to objective considerations when it described the
    obviousness inquiry as “expansive and flexible” and noted
    that Graham “invite[s] the courts, where appropriate, to
    look at any secondary considerations that would prove
    instructive.” KSR, 
    550 U.S. at 415
    . And, in i4i, the Court
    reaffirmed both the scope and placement of the burden of
    proof in these circumstances. 
    131 S. Ct. at 2245, n.4
    .
    In i4i, the Court was asked to articulate the standard
    of proof a party must satisfy to prove an invalidity de-
    fense. 
    131 S. Ct. at 2242
    . The Court held that the stan-
    dard of proof is proof by clear and convincing evidence.
    
    Id.
     In explaining that holding, the Court differentiated
    between the concepts of burden of proof, burden of pro-
    duction, burden of persuasion, and standard of proof. 
    Id. at 2245
    . As the Court explained, the commonly used term
    “burden of proof” encompasses the concepts of “burden of
    persuasion” and “burden of production.” 
    Id.
     at 2245 n.4.
    The burden of persuasion specifies “which party loses if
    the evidence is balanced,” while the burden of production
    specifies “which party must come forward with evidence
    at various stages in the litigation.” 
    Id.
     at 2245 n.4. The
    standard of proof, the court further explained, specifies
    “how difficult it will be for the party bearing the burden of
    persuasion to convince the jury of the facts in its favor.”
    
    Id.
     at 2245 n.4.
    The Court resorted to common-law principles to de-
    termine that the standard of proof is proof by clear and
    convincing evidence because the Patent Act does not
    explicitly articulate the standard of proof. 
    Id.
     at 2245–
    EURAND   v. MYLAN                                         28
    46. By contrast, the Court noted, the Patent Act specifies
    that the burden of proof is placed on the party challenging
    validity: “The burden of establishing invalidity of a patent
    or any claim thereof shall rest on the party asserting such
    invalidity.” 
    Id. at 2245
     (quoting 
    35 U.S.C. § 282
    ). The
    Court provided no indication that it believes the burden of
    persuasion should shift to the patentee at some point to
    prove nonobviousness. 5
    Finally, not only is Stratoflex the law, it is sound in
    requiring that a fact finder consider the objective evidence
    before reaching an obviousness determination.            The
    objective considerations, when considered with the bal-
    ance of the obviousness evidence in the record, guard as a
    check against hindsight bias. Graham, 
    383 U.S. at 36
    (quoting Monroe Auto Equip. Co. v. Heckethorn Mfg. &
    Supply Co., 
    332 F.2d 406
    , 412 (6th Cir. 1964)). In Gra-
    ham, the Court recognized the danger of hindsight bias
    and the ameliorative effect that the objective considera-
    tions might offer. In discussing the utility of the objective
    considerations, the Court cited a law review note pub-
    lished after the nonobviousness requirement was enacted
    in the 1952 Patent Act. 
    Id.
     at 18 (citing Richard L. Rob-
    5   It is true that, in most cases, it is a patentee who
    chooses to offer proof of objective considerations as evi-
    dence of nonobviousness. It is also true that district
    courts will often impose a discovery obligation on patent-
    ees to be the first to produce evidence relating to objective
    considerations. And, it is true that district courts also
    often require patentees to present their objective evidence
    during their case in chief to make an efficient use of time
    and resources during trial, relying on their authority
    under Federal Rule of Evidence 611(a) to structure the
    presentation of evidence. Those realities do not change
    the fact that the party challenging validity bears the
    burden of persuasion throughout the litigation. i4i, 
    131 S. Ct. at
    2245 & n.4.
    29                                         EURAND   v. MYLAN
    bins, Subtests of “Nonobviousness”: A Nontechnical Ap-
    proach to Patent Validity, 
    112 U. Pa. L. Rev. 1169
     (1964)
    (“Robbins”)). In that note, the author argued that the
    instruments of decision-making applied in patent cases at
    the time were inadequate and allowed judges to rely on
    “judicial hunches,” thereby deciding cases on extralegal
    grounds. Robbins, 112 U. Pa. L. Rev. at 1170 & n.11
    (citing Joseph C. Hutcheson, Jr., The Judgment Intuitive:
    The Function of the “Hunch” in Judicial Decisions, 14
    Cornell L.Q. 274, 278 (1929)). Such “judicial hunches” are
    encouraged by hindsight bias. As one commentator
    recently observed, “decision-makers unconsciously let
    knowledge of the invention bias their conclusion concern-
    ing whether the invention was obvious in the first in-
    stance.”    Gregory N. Mandel, Patently Non-Obvious:
    Empirical Demonstration that the Hindsight Bias Renders
    Patent Decisions Irrational, 
    67 Ohio St. L.J. 1391
    , 1393
    (2006). In other words, knowing that the inventor suc-
    ceeded in making the patented invention, a fact finder
    might develop a hunch that the claimed invention was
    obvious, and then construct a selective version of the facts
    that confirms that hunch. This is precisely why the
    Supreme Court explained that objective considerations
    might prevent a fact finder from falling into such a trap,
    observing that objective considerations might serve to
    “resist the temptation to read into the prior art the teach-
    ings of the invention in issue.” 
    383 U.S. at 36
    . 6 And, it is
    6  To be sure, courts must exercise care in assessing
    proffered evidence of objective considerations, giving such
    evidence weight only where the objective indicia are
    “attributable to the inventive characteristics of the dis-
    covery as claimed in the patent.” See Rochelle Cooper
    Dreyfuss, The Federal Circuit: A Case Study in Special-
    ized Courts, 
    64 N.Y.U. L. Rev. 1
    , 10 (1989) (noting that
    this court has imposed such a “nexus” requirement on the
    objective considerations). See also Ormco Corp. v. Align
    EURAND   v. MYLAN                                        30
    precisely why fact finders must withhold judgment on an
    obviousness challenge until it considers all relevant
    evidence, including that relating to the objective consid-
    erations.
    In sum, opinions of this court should not be read to
    require a burden-shifting framework in derogation of
    Stratoflex’s directive that objective evidence be considered
    before making an obviousness determination and in
    disregard of where the burdens of proof and persuasion
    are properly placed in district court litigation. 7 Such a
    Tech., Inc., 
    463 F.3d 1299
    , 1311–12 (Fed. Cir. 2006)
    (noting that a nexus must exist between a product’s
    commercial success and the claimed invention).
    7     It appears that the language discussing a two-
    part, burden-shifting inquiry may have originated in and
    been borrowed from the test employed in appeals from the
    Board of Patent Appeals and Interferences. In Iron Grip
    Barbell, for example, we stated that a “presumption of
    obviousness” that exists when a claimed invention falls
    within a range disclosed in the prior art could be “rebut-
    ted if it can be shown: (1) That the prior art taught away
    from the claimed invention . . . or (2) that there are new
    and unexpected results.” 392 F.3d at 1322. For that
    proposition, we cited In re Geisler, 
    116 F.3d 1465
    , 1471
    (Fed. Cir. 1997), and In re Woodruff, 
    919 F.2d 1575
    , 1578
    (Fed. Cir. 1990). Both of those cases were appeals from
    obviousness rejections during prosecution. In re Geisler,
    
    116 F.3d at 1467
    ; In re Woodruff, 
    919 F.2d at 1575
    .
    Unlike in district court litigation, a burden-shifting
    framework makes sense in the prosecution context. The
    prima facie case furnishes a “procedural tool of patent
    examination, allocating the burdens of going forward as
    between examiner and applicant.” In re Oetiker, 
    977 F.2d 1443
    , 1445 (Fed. Cir. 1992). During prosecution, a patent
    applicant, as a practical matter, may not have the oppor-
    tunity to present objective evidence unless and until an
    examiner reviews the application and issues an obvious-
    31                                         EURAND   v. MYLAN
    reading disregards our own precedent and is inconsistent
    with Supreme Court case law, including very recent case
    law.
    3.
    The district court appears to have fallen into the un-
    derstandable but improper trap of constructing a selective
    version of the facts relating to the objective considerations
    so as to confirm its hunch that the asserted claims were
    obvious. The district court focused on objective evidence
    that supported its obviousness determination, but ignored
    ness rejection. This is because “the examiner bears the
    initial burden, on review of the prior art or on any other
    ground, of presenting a prima facie case of unpatentabil-
    ity. If that burden is met, the burden of coming forward
    with evidence or argument shifts to the applicant.” 
    Id.
    Courts should not apply the burden-shifting framework
    for patentability appeals to invalidity determinations
    appealed from a district court, however, because the
    prosecution and litigation contexts are distinct.
    In the prosecution context, not only are the decision
    maker and the patent holder the only two parties in-
    volved, but that decision maker—the examiner—is re-
    quired to determine patentability by a preponderance of
    the evidence. 
    Id.
     Evidence of objective considerations
    also may not be available until years after an application
    is filed, and until long after the examiner first considers
    the prior art. Litigation differs significantly from the
    examination process. First, in the litigation context,
    validity, rather than patentability, is the issue. The
    challenged patent enjoys a presumption of validity, and
    the challenger must convince a third-party decision
    maker of the patent’s invalidity by clear and convincing
    evidence. 
    35 U.S.C. § 282
    ; i4i, 
    131 S. Ct. at 2242
    . And, in
    litigation, all relevant evidence is presented to the fact
    finder in a single proceeding. There is simply no practical
    need to impose a burden-shifting framework in litigation.
    EURAND   v. MYLAN                                        32
    other evidence that cast the objective considerations in a
    light favorable to Cephalon. And, it is clear that the
    district court assumed that it was Cephalon’s burden to
    disprove the court’s initial obviousness finding.
    Had the district court, instead, considered the objec-
    tive evidence in its entirety before making an obviousness
    finding, and considered that evidence in light of the actual
    burden imposed upon a patentee and a patent challenger,
    much of that evidence would have encouraged the district
    court to question the claim that the mere existence of an
    immediate-release formulation of cyclobenzaprine made
    an extended-release version of that drug obvious. Specifi-
    cally, we find that evidence of a longfelt need for an
    extended-release formulation and the failure of others to
    formulate one strongly support a conclusion of nonobvi-
    ousness. We address each of these considerations.8
    8   We find no error in the district court’s conclusion
    that Cephalon failed to offer adequate proof of reduced
    sedation through its formulation and, thus, could not rely
    on unexpected results to support its contention that
    Mylan and Par failed to prove obviousness by clear and
    convincing evidence. While we question the trial court’s
    interpretation of Eurand’s evidence of commercial success,
    moreover, we cannot find clear error therein. That these
    objective criteria do not strongly support a finding of
    nonobviousness does not affect our conclusions, however.
    On both points, we find the evidence to be neutral; while
    they do not support a finding of nonobviousness, they add
    little to Mylan and Par’s claim of obviousness. While
    evidence of reduced sedation may not have been strong,
    the patents in suit do not claim that benefit; they claim
    only therapeutic effectiveness. And, while Amrix’s com-
    mercial success may be slow in coming, it is clear its
    success is increasing, as its benefits—particularly greater
    compliance—become known.
    33                                         EURAND   v. MYLAN
    a.
    Cephalon claims that another pharmaceutical com-
    pany, ALZA, tried but failed to develop an extended-
    release cyclobenzaprine formulation. 9 The district court
    rejected this claim, because, in its view, ALZA’s goals
    were different than Cephalon’s. Mylan and Par endorse
    the district court’s reasoning. The district court, however,
    ignored the fact that Cephalon and ALZA shared a com-
    mon goal: to make a therapeutically effective product.
    This was clear error.
    Evidence that others tried but failed to develop a
    claimed invention may carry significant weight in an
    obviousness inquiry. “While absolute certainty is not
    necessary to establish a reasonable expectation of success,
    there can be little better evidence negating an expectation
    of success than actual reports of failure.” Boehringer
    Ingelheim Vetmedica, Inc. v. Schering-Plough Corp., 
    320 F.3d 1339
    , 1354 (Fed. Cir. 2003). This is particularly true
    when the evidence indicates that others found develop-
    ment of the claimed invention difficult and failed to
    achieve any success. Advanced Display Sys. v. Kent State
    Univ., 
    212 F.3d 1272
    , 1285 (Fed. Cir. 2000). In such
    circumstances, “evidence of failed attempts by others
    could be determinative on the issue of obviousness.” 
    Id.
    The evidence of ALZA’s failure to develop an ex-
    tended-release formulation strongly supports a nonobvi-
    ousness finding. In the late 1990s, ALZA performed
    pharmacokinetic modeling and created a PK profile for
    immediate-release cyclobenzaprine dosed three times a
    9   Cephalon also claims that Merck and Schering-
    Plough tried but failed to develop an extended-release
    formulation. The evidence of Merck’s and Schering-
    Plough’s alleged failures, however, is weak, and the
    district court did not clearly err in disregarding it.
    EURAND   v. MYLAN                                        34
    day. This approach was similar to the manner in which
    Drs. Venkatesh and Clevenger modeled their PK profile.
    The immediate-release PK profile that ALZA modeled
    represented “peaks and valleys” on a graph, with blood
    plasma concentrations undulating as time passed. ALZA
    then hypothesized a PK profile for an extended-release
    cyclobenzaprine product based on its model for the imme-
    diate-release product. For its extended-release PK profile,
    ALZA chose a straight line that cut through the immedi-
    ate-release profile, staying below the peaks and above the
    valleys. ALZA hoped that staying below the peaks would
    avoid side effects and that staying above the valleys
    would maintain therapeutic effectiveness. Clinical trials,
    however, revealed that ALZA’s product was not therapeu-
    tically effective. ALZA lost $10 million in its unsuccessful
    attempt to develop an extended-release formulation.
    At trial, Cephalon called a former ALZA vice presi-
    dent, Dr. Samuel Saks. Cephalon’s counsel showed Dr.
    Saks Cephalon’s PK profile. That profile indicated that
    Cephalon had departed from ALZA’s attempt to cut
    through the immediate release PK profile’s peaks and
    valleys. Rather, Cephalon had chosen a PK profile in
    which the Cmax rose higher and the minimum blood
    plasma concentration (Cmin) dipped lower than those of the
    immediate-release profile. After reviewing Cephalon’s PK
    profile, Dr. Saks expressed surprise that Cephalon suc-
    ceeded, because he believed a lower Cmin would be less
    effective. Thus, where ALZA failed to develop a therapeu-
    tically effective product, Cephalon took a materially
    different approach and succeeded. Evidence that others
    were “‘going in different ways’ is strong evidence that the
    [inventor’s] way would not have been obvious.” Panduit
    Corp. v. Dennison Mfg. Co., 
    774 F.2d 1082
    , 1099 (Fed. Cir.
    1985), vacated and remanded on other grounds, 
    475 U.S. 809
     (1986).
    35                                         EURAND   v. MYLAN
    The district court disregarded ALZA’s failures. ALZA
    intended to make a formulation that was not only thera-
    peutically effective, but one that also reduced side effects.
    Cephalon’s patents do not cover a formulation that re-
    duces side effects. The district court noted that an alleged
    failure must be directed to the problem that a patent
    purports to solve. Symbol Techs., Inc. v. Opticon, Inc., 
    935 F.2d 1569
    , 1578 (Fed. Cir. 1991). Because ALZA had the
    additional goal of reducing side effects, the district court
    believed that ALZA’s failure was not directed to the
    problem that Cephalon’s patents purport to solve.
    The district court clearly erred because it disregarded
    that Cephalon and ALZA did share a central common
    goal: to create a therapeutically effective product. There
    is no dispute that AZLA sought to create a product that
    worked. The patents in suit, of course, cover a therapeu-
    tically effective PK profile. The district court was not
    required to disregard Cephalon and ALZA’s common goal
    simply because ALZA had an additional goal not encom-
    passed by the patents in suit. The purpose of evidence of
    failure of others is to show “indirectly the presence of a
    significant defect in the prior art, while serving as a
    simulated laboratory test of the obviousness of the solu-
    tion to a skilled artisan.” Symbol Techs., 
    935 F.2d at
    1578–79 (quoting Robbins, 112 U. Pa. L. Rev. at 1173).
    ALZA’s failure accomplishes that purpose, confirming
    that a therapeutically effective PK profile was lacking in
    the prior art and that skilled artisans struggled to attain
    it. Such a scenario is classic evidence of nonobviousness.
    See, e.g., Advanced Display Sys., 212 F.3d at 1285 (hold-
    ing that the objective evidence supported an obviousness
    finding where others had “tried for a long time” to develop
    the claimed invention but found it “very hard” and “were
    all not successful”). ALZA’s failure to develop a therapeu-
    tically effective product, in sum, is keyed to the problem
    EURAND   v. MYLAN                                          36
    that the patents in suit purport to solve, and it supports a
    finding that Cephalon’s accomplishment was not obvious
    to those skilled in the art.
    b.
    Cephalon also claimed that a longfelt need existed for
    an extended-release cyclobenzaprine formulation and that
    Amrix satisfied that need. The district court rejected that
    argument because it believed Cephalon failed to offer any
    expert testimony to support it. The district court’s as-
    sessment of this factor was inadequate.
    Longfelt need is closely related to the failure of others.
    Evidence is particularly probative of obviousness when it
    demonstrates both that a demand existed for the patented
    invention, and that others tried but failed to satisfy that
    demand. See, e.g., In re Piasecki, 
    745 F.2d 1468
    , 1475
    (Fed. Cir. 1984) (finding nonobviousness where the evi-
    dence demonstrated a failure of others to provide a feasi-
    ble solution to a longstanding problem); Alco Standard
    Corp. v. Tenn. Valley Auth., 
    808 F.2d 1490
    , 1500 (Fed.
    Cir. 1986) (affirming a nonobviousness finding where the
    evidence showed that the relevant industry had searched
    for more than a decade for a reliable solution and that
    major manufacturers in the industry had tried but failed
    to develop such a solution).
    Cephalon’s proof indicates that a longfelt need existed
    for a therapeutically effective, extended-release cycloben-
    zaprine formulation. The immediate-release formulation
    existed for decades, but that formulation’s regimen of
    multiple daily doses led to poor patient compliance. As
    discussed above, moreover, others tried but failed to
    develop an extended-release version. In addition to these
    facts, Cephalon called Dr. David Steiner, a physician who
    has practiced in pain management for more than a dec-
    ade. Dr. Steiner discussed his experiences treating his
    37                                        EURAND   v. MYLAN
    patients’ pain in the clinic. He testified that patient
    compliance with a medical regimen is important and that
    he began prescribing Amrix, in part, because of the pros-
    pect of more convenient dosing for his patients.
    Not only was the district court wrong that Cephalon
    produced no expert testimony on this issue, but the dis-
    trict court was wrong to ignore the non-expert evidence
    proffered on this point. In combination with compelling
    evidence of the failure of others to produce an extended-
    release formulation, this factor further supports a nonob-
    viousness finding.
    4.
    Where, as here, the obviousness determination turns
    on whether one of ordinary skill in the art would have
    expected that a particular formulation of an extended-
    release drug would be successful—in other words, would
    render a therapeutically effective treatment—objective
    indicia of failure of others and longfelt need are particu-
    larly telling. The district court would have encountered a
    different landscape had it examined the objective evidence
    in light of the absence of a known PK/PD relationship.
    ALZA’s failure to develop a therapeutically effective,
    extended-release formulation suggests that skilled arti-
    sans would not have reasonably expected to succeed in
    developing the claimed formulation. The long delay
    between the marketing of an immediate-release formula-
    tion and Amrix, and Dr. Steiner’s testimony of longfelt
    need, moreover, supports the inference that it was diffi-
    cult for researchers to create a therapeutically effective,
    extended-release product. Because a desire existed for
    such a product, researchers, presumably, would have
    created one if they were able to do so.
    Rather than supporting a finding of obviousness, the
    most relevant objective considerations, when considered
    EURAND   v. MYLAN                                         38
    as part of the totality of the evidence, support a nonobvi-
    ousness finding.
    D.
    The record, in sum, is insufficient to support a conclu-
    sion of obviousness by clear and convincing evidence. At
    its core, Mylan and Par’s proof of obviousness is that the
    claimed PK profile is bioequivalent to the immediate-
    release profile. In rejecting the sufficiency of Mylan and
    Par’s proof, we do not hold that bioequivalence can never
    serve as evidence of obviousness. Indeed, it is most
    certainly relevant to that inquiry. We only hold that, on
    the facts of this case—in which therapeutic effectiveness
    is a claimed limitation and the parties do not dispute that
    cyclobenzaprine lacked a known PK/PD relationship—
    Mylan and Par cannot rely on bioequivalence as the sole
    basis for an obviousness finding, particularly given the
    heavy burden of proof imposed on them in this context.
    Indeed, defense counsel acknowledged at oral argument
    that Mylan and Par are not requesting a categorical rule
    that it is always obvious to try to target bioequivalence
    when formulating an extended-release formulation. See
    Oral       Argument       at      8:54,      available     at
    http://www.cafc.uscourts.gov/oral-argument-
    recordings/2011-1399/all. If we were to affirm the district
    court’s obviousness ruling on the basis of this record, we
    effectively would announce such a rule. 10
    10  The parties have not cited any cases in which the
    presence or absence of a known PK/PD relationship was
    determinative. Indeed, in other cases, it appears that the
    parties and the court assumed bioequivalence would
    produce a therapeutically effective result. See Abbott
    Labs. v. Andrx Pharms., Inc., 
    452 F.3d 1331
    , 1340–43
    (Fed Cir. 2006) (finding a substantial question of validity
    on a preliminary injunction motion where the prior art
    disclosed substantially bioequivalent PK values, but
    39                                         EURAND   v. MYLAN
    The district court erred in finding that Mylan and Par
    proved that the asserted claims are obvious by clear and
    convincing evidence.
    IV.
    We address next Mylan and Par’s best mode defense.
    The district court rejected Mylan and Par’s claim that the
    patents in suit are invalid for failure to disclose the best
    mode. Although the district court applied the incorrect
    test for a best mode disclosure violation, the district
    court’s findings support its ultimate conclusion that no
    best mode disclosure violation existed.
    A patent’s specification must “set forth the best mode
    contemplated by the inventor of carrying out his inven-
    tion.” 
    35 U.S.C. § 112
     ¶ 1 (2006). The version of the
    Patent Act currently in effect provides that, although an
    applicant must disclose the best mode to register a patent,
    a party to a lawsuit may not rely on an alleged best mode
    disclosure violation to cancel, invalidate, or hold a patent
    otherwise unenforceable.        Id.; Leahy-Smith America
    Invents Act, Pub. L. No. 112-29, sec. 15(a), 
    125 Stat. 284
    ,
    328 (2011) (to be codified at 
    35 U.S.C. § 282
     ¶ 2(3)(A)).
    That provision, however, is inapplicable to this case
    because it is the product of amendments made to the
    Patent Act that became effective after this action was
    filed. Leahy-Smith America Invents Act, Pub. L. No. 112-
    29, sec. 15(c), 
    125 Stat. 284
    , 328 (2011) (providing that the
    best mode amendments apply only to actions commenced
    failing to address whether bioequivalent PK values would
    produce a therapeutically effective result); Adams Respi-
    ratory Therapeutics, Inc. v. Perrigo Co., 
    616 F.3d 1283
    ,
    1289 (Fed. Cir. 2010) (reversing a district court’s grant of
    summary judgment because a fact finder could reasonably
    find infringement based on the accused ANDA product’s
    having a Cmax equivalent to that of a standard immediate-
    release product).
    EURAND   v. MYLAN                                         40
    on or after the effective date of the amendments). The
    version of the Patent Act applicable to this case permits
    an accused infringer to assert a best mode disclosure
    violation as a defense. 
    35 U.S.C. § 282
     ¶ 2(3) (2006).
    A defense of failure to disclose the best mode is a
    question of fact. Zygo Corp. v. Wyko Corp., 
    79 F.3d 1563
    ,
    1566–67 (Fed. Cir. 1996). We review a lower court’s
    finding of no best mode disclosure violation for clear error.
    
    Id.
    Mylan and Par claim that the specification fails to
    disclose the best mode because it omits a particular range
    of dew points. The claimed cyclobenzaprine formulation
    is made with a coated bead. During the formulation
    process, the bead is placed in a fluid bed machine, which
    sprays a layer of the drug and a layer of extended-release
    coating on the bead. The dew point of the air entering the
    fluid bed must be controlled. Mylan and Par claim that
    Dr. Venkatesh preferred dew points of 6–12ºC for imme-
    diate-release coating and 7–16ºC for extended-release
    coating, with target dew points of 8ºC and 10ºC, respec-
    tively. The specification does not disclose those dew
    points.
    To determine whether a best mode disclosure viola-
    tion exists, a fact finder applies a two-prong test. First,
    the fact finder determines whether, at the time the appli-
    cation was filed, the inventor possessed a best mode for
    practicing the invention. Eli Lilly & Co. v. Barr Labs.,
    Inc., 
    251 F.3d 955
    , 963 (Fed. Cir. 2001) (citations omit-
    ted). A subjective inquiry, the first prong focuses on “the
    inventor’s state of mind at the time he filed the patent
    application, and asks whether the inventor considered a
    particular mode of practicing the invention to be superior
    to all other modes at the time of filing.” Teleflex, Inc. v.
    41                                         EURAND   v. MYLAN
    Ficosa N. Am. Corp., 
    299 F.3d 1313
    , 1330 (Fed. Cir. 2002)
    (citation omitted).
    The district court found that Dr. Venkatesh preferred
    particular dew points at the time the applications were
    filed. In March 2003, before the patent applications were
    filed, Dr. Venkatesh told the FDA that, during scale-up
    experiments, “the dew point of the incoming air was
    monitored by setting the control at a very low target of
    8°C (6–12)°C” and that “[d]ecreasing the dew point of the
    incoming process air reduced the tackiness of the beads
    and reduced the tendency of the coated beads from clump-
    ing together.” Dr. Venkatesh acknowledged that dew
    points could affect dissolution: “If you don’t use the proper
    optimization, then you may not get good yield or you may
    not get the proper coating . . . [t]hen the product will not
    be good . . . .” While Cephalon argued to the district court
    that Dr. Venkatesh did not have a subjective belief in a
    best mode, Cephalon does not contest on appeal the
    district court’s finding that he did have such a belief, and
    we do not find that finding to have been clearly erroneous
    in any event.
    If the inventor possessed a best mode at the time of
    filing, as the district court found Dr. Venkatesh did, the
    second prong of the inquiry requires the fact finder to
    determine whether the specification discloses sufficient
    information such that one reasonably skilled in the art
    could practice the best mode. Eli Lilly, 
    251 F.3d at 963
    (citations omitted). Because the second prong focuses on
    what the specification teaches to a person of ordinary skill
    in the art, the inquiry is objective. 
    Id.
    Mylan and Par mistakenly attempt to cast the second
    prong as an inquiry concerning whether Dr. Venkatesh
    “concealed” his best mode. Defs.’ Resp. & Reply Br. 50.
    That characterization is inaccurate. Concealment impli-
    EURAND   v. MYLAN                                       42
    cates an inventor’s state of mind, which is inconsistent
    with an objective inquiry focused on what the specifica-
    tion teaches to a skilled artisan. U.S. Gypsum Co. v. Nat’l
    Gypsum Co., 
    74 F.3d 1209
    , 1215–16 (Fed. Cir. 1996). As
    we explained in U.S. Gypsum, this court has used the
    term “concealment” as a shorthand way of inquiring about
    the adequacy of the disclosure:
    The “concealment” language of our case
    law originated in In re Gay, 
    309 F.2d 769
    (CCPA 1962). In Gay, the Court of Cus-
    toms and Patent Appeals (CCPA) ex-
    plained that “the sole purpose of [the best
    mode] requirement is to restrain inventors
    from applying for patents while at the
    same time concealing from the public pre-
    ferred embodiments of their inventions
    which they have in fact conceived.” . . .
    Subsequently, the CCPA clarified that
    “only evidence of concealment (whether
    accidental or intentional) is to be consid-
    ered. That evidence, in order to result in
    affirmance of a best mode rejection, must
    tend to show that the quality of an appli-
    cant’s best mode disclosure is so poor as to
    effectively result in concealment.” In re
    Sherwood, 
    613 F.2d 809
    , 816 (CCPA
    1980).
    
    Id.
     Thus, the proper inquiry focuses on the adequacy of
    the disclosure rather than motivation for any nondisclo-
    sure. See also Bayer AG v. Schein Pharms., Inc., 
    301 F.3d 1306
    , 1320 (Fed. Cir. 2002) (explaining that the inquiry is
    objective).
    The district court did not directly address whether the
    specification adequately disclosed the best mode. Rather,
    43                                         EURAND   v. MYLAN
    the district court found that the dew points did not need
    to be disclosed because they amounted to routine details.
    We have recognized that routine details apparent to one
    of ordinary skill in the art need not be disclosed to satisfy
    the best mode disclosure requirement. E.g., Teleflex, 
    299 F.3d at
    1331–32; Eli Lilly, 
    251 F.3d at 963
    ; and Young
    Dental Mfg. Co. v. Q3 Special Prods., Inc., 
    112 F.3d 1137
    ,
    1144 (Fed. Cir. 1997).
    To conclude that the optimal dew points were routine
    details exempt from disclosure, the district court was
    required to find that the dew points would be apparent to
    a person of ordinary skill in the art. Teleflex, 
    299 F.3d at
    1331–32. The district court found the following: (1) it
    would be routine to control humidity during product
    fabrication; (2) the allegedly concealed dew points were
    within the normal operating range of a commonly used
    fluid-bed coating device; (3) Dr. Venkatesh’s optimal dew
    point was within the normal operating range; and (4) the
    defendants’ own technicians were able to optimize the
    dew point in just a few days. That evidence does not
    indicate that the optimal dew points would actually be
    apparent to one of ordinary skill in the art. If they were,
    the evidence, presumably, would indicate that skilled
    artisans would know the optimal dew points and program
    the fluid bed accordingly before commencing production.
    The district court’s findings indicate, rather, that some,
    albeit minimal, work was required to ascertain the opti-
    mal dew points.
    Rather than finding that the dew points were routine
    details apparent to one of ordinary skill in the art, the
    district court could, and should, have made a more fun-
    damental finding: that the specification need not disclose
    the optimal dew points to enable skilled artisans to prac-
    tice the best mode. See U.S. Gypsum, 
    74 F.3d at
    1215–16
    (focusing the inquiry on the adequacy of the disclosure).
    EURAND   v. MYLAN                                       44
    As one expert, Dr. Robert Williams, explained, skilled
    artisans do not begin the fabrication process by attempt-
    ing to attain a particular dew point in the fluid bed.
    Rather, they attempt to manipulate and harmonize a
    number of parameters, including, for example, air humid-
    ity, inlet air quantity, inlet air temperature, and spray
    rate. Dew point is a function of the other parameters.
    The totality of these parameters, when harmonized,
    creates the optimal condition for fabricating product.
    Thus, as the district court’s findings suggest, skilled
    artisans would expect to attain the optimal dew points
    during the ordinary harmonization process by employing
    routine steps such as controlling the humidity and operat-
    ing the fluid bed within the normal operating range.
    Because harmonization—a process known to skilled
    artisans—would produce the optimal dew points, the
    specification need not disclose them to enable skilled
    artisans to practice the best mode. The disclosure is
    adequate without them.
    Mylan and Par argue that, because the dew points
    materially affect the claimed invention, express disclosure
    in the specification was required. For this proposition,
    they cite Bayer, 
    301 F.3d at 1312
    . Mylan and Par mis-
    read Bayer. There, we held that, to prove inadequate
    disclosure of the best mode, an accused infringer must
    prove that the undisclosed information affects the proper-
    ties of the claimed invention. 
    Id. at 1319
    . The panel also
    held that an accused infringer may prove a best mode
    disclosure violation if the undisclosed subject matter
    materially affects the properties of the claimed invention,
    even if the undisclosed subject matter is not strictly
    within the bounds of the patent claims. 
    Id. at 1316
    .
    Bayer created an exception to the general rule that “the
    best mode disclosure requirement only refers to the
    invention defined by the claims.” 
    Id.
     at 1315–16. Bayer is
    45                                         EURAND   v. MYLAN
    inapposite here because there is no dispute that the dew
    points are within the bounds of the asserted claims: The
    claims cover a particular dissolution profile, and dew
    point affects dissolution. The only issue here is whether
    the disclosure is adequate to enable a person of ordinary
    skill in the art to practice the invention incorporating the
    optimal dew points. Mylan and Par cannot avoid that
    issue merely by claiming that the dew points are material
    to the claimed invention.
    Invalidation as a result of a best mode disclosure vio-
    lation requires proof by clear and convincing evidence.
    Teleflex, 
    299 F.3d at 1330
    . Mylan and Par cannot meet
    that burden because the record indicates that skilled
    artisans could readily obtain the optimal dew points using
    a common fluid bed. We find, therefore, that the district
    court did not err in rejecting Mylan and Par’s best mode
    defense.
    V.
    We address next Mylan’s appeal in Case No. 2011-
    1399. Mylan appeals from the district court’s order
    entering an injunction against launch of its generic ver-
    sion of Amrix. Mylan argues that it is virtually always
    improper to enjoin a prevailing party from acting in a
    manner authorized by a district court’s own judgment;
    that it is particularly inappropriate to enter an injunction
    pending appeal against a prevailing generic in an ANDA
    action; and that, even if such an injunction is permissible
    in the abstract, the district court abused its discretion
    when it entered an injunction in this case. Mylan con-
    tends that it is entitled to recapture damages, capped by
    the amount of the bond imposed, regardless of the out-
    come on appeal.
    Given our ruling today, Mylan is no longer a prevail-
    ing party or a prevailing generic, however. We have
    EURAND   v. MYLAN                                         46
    reversed the judgment of invalidity upon which Mylan
    predicates its objections in this appeal. If our resolution
    of the appeal in Case No. 2011-1409 resulted in an order
    directing judgment in favor of Cephalon and a permanent
    injunction, Mylan’s own appeal would certainly be moot.
    See Grupo Mexicano de Desarrollo, S.A. v. Alliance Bond
    Fund, Inc., 
    527 U.S. 308
    , 314 (1998). In Grupo Mexicano
    de Desarrollo, the Supreme Court explained:
    [I]f [a plaintiff’s] lawsuit turns out to be
    meritorious—if he is found to be entitled
    to the permanent injunction that he
    seeks—even if the preliminary injunction
    was wrongly issued (because at that stage
    of the litigation the plaintiff’s prospects of
    winning were not sufficiently clear, or the
    plaintiff was not suffering irreparable in-
    jury) its issuance would in any event be
    harmless error. The final injunction es-
    tablishes that the defendant should not
    have been engaging in the conduct that
    was enjoined.
    
    Id.
     at 314–15. See also Global NAPs, Inc. v. Verizon New
    England, Inc., 
    489 F.3d 13
    , 22 (1st Cir. 2007) (“[A] party
    is wrongfully enjoined when it had a right all along to do
    what it was enjoined from doing.“); Blumenthal v. Merrill
    Lynch, Pierce, Fenner & Smith, Inc., 
    910 F.2d 1049
    , 1054
    (2d Cir. 1990) (“A party has been ‘wrongfully enjoined’ . . .
    if it is ultimately found that the enjoined party had at all
    times the right to do the enjoined act.”) Thus, if Mylan
    was simply enjoined from engaging in conduct in which it
    had no right to engage, Mylan’s complaints about that
    injunction become meaningless. This simple principle
    may or may not ultimately apply in this case, however. It
    is unclear at this stage what the ultimate resolution of
    this matter will be and whether launch of Mylan’s generic
    47                                        EURAND   v. MYLAN
    will be deemed unauthorized. See, e.g., Grupo Mexicano
    de Desarrollo, 527 U.S. at 314–15 (indicating that where a
    permanent injunction either does not ultimately issue or
    is narrower in scope than a preliminary injunction, a
    claim against the bond could lie).
    Here, it is unclear whether a final judgment against
    Mylan will be entered and, if so, what the scope of an
    injunctive remedy, if any, might be. There is much litiga-
    tion that is yet to occur—both as to Cephalon’s claims for
    relief and as to Mylan’s currently stayed counterclaims.
    For these reasons, we find it premature to address My-
    lan’s claim on the appeal bond or to resolve the questions
    Mylan poses regarding the circumstances under which, or
    the standards by which, an injunction pending appeal
    may be imposed on a prevailing party in an ANDA action.
    We dismiss Mylan’s appeal without prejudice to reassert a
    claim for damages against the appeal bond if and when
    such a claim might be ripe and appropriate. In the in-
    terim, the appeal bond will remain in place unless the
    parties stipulate to its release.
    VI.
    On a final matter, we note that, because Mylan’s pat-
    ent misuse and antitrust claims remained unresolved at
    the time of appeal, the parties did not appeal from a final
    judgment, which normally precludes an appellate court
    from exercising jurisdiction. See Fed. R. Civ. P. 54. After
    the appeals were filed, the parties moved the district
    court for entry of a certificate pursuant to Rule 54(b) of
    the Federal Rules of Civil Procedure, which would allow
    the disposed issues to be immediately appealed. The
    district court granted the motion and entered the Rule
    54(b) certificate. We have permitted parties to establish
    appellate jurisdiction with a nunc-pro-tunc Rule 54(b)
    certificate. Storage Tech. Corp. v. Cisco Sys., Inc., 329
    EURAND   v. MYLAN                                            
    48 F.3d 823
    , 829–30 (Fed. Cir. 2003); State Contracting &
    Eng’g Corp. v. Fla., 
    258 F.3d 1329
    , 1334–35 (Fed. Cir.
    2001). While the parties should have moved for entry of a
    Rule 54(b) certificate before filing their appeals, the late-
    filed certificate is sufficient to establish appellate jurisdic-
    tion under our precedent.
    VII.
    We reverse and vacate the district court’s invalidity
    judgment and affirm its best mode ruling. We dismiss as
    premature Mylan’s appeal from the district court’s entry
    of the injunction. To allow the district court an opportu-
    nity to assess the propriety of a preliminary injunction
    pending further proceedings, the injunction will remain in
    place for forty-five days post-mandate, or until further
    order of the district court, whichever occurs sooner.
    AFFIRMED IN PART, REVERSED IN PART,
    VACATED IN PART, DISMISSED IN PART
    

Document Info

Docket Number: 2011-1399

Filed Date: 4/16/2012

Precedential Status: Precedential

Modified Date: 2/19/2016

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