  United States Court of Appeals
      for the Federal Circuit
                ______________________

 FOREST LABORATORIES, LLC, FKA FOREST
LABORATORIES, INC., FOREST LABORATORIES
            HOLDINGS LTD.,
         Plaintiffs-Cross-Appellants

                           v.

       SIGMAPHARM LABORATORIES, LLC,
              Defendant-Appellee

   HIKMA PHARMACEUTICALS LLC, HIKMA
       PHARMACEUTICALS PLC, HIKMA
PHARMACEUTICALS USA INC., FKA WEST-WARD
 PHARMACEUTICALS CORP., BRECKENRIDGE
      PHARMACEUTICAL INC., ALEMBIC
 PHARMACEUTICALS LTD., ALEMBIC GLOBAL
 HOLDING S.A., ALEMBIC PHARMACEUTICALS
   INC., AMNEAL PHARMACEUTICALS LLC,
 AMNEAL PHARMACEUTICALS OF NEW YORK
 LLC, AMNEAL PHARMACEUTICALS CO. INDIA
                  PVT. LTD.,
             Defendants-Appellants
            ______________________

2017-2369, 2017-2370, 2017-2372, 2017-2373, 2017-2374,
2017-2375, 2017-2376, 2017-2389, 2017-2412, 2017-2436,
           2017-2438, 2017-2440, 2017-2441
               ______________________

    Appeals from the United States District Court for the
District of Delaware in Nos. 1:14-cv-01119-MSG, 1:14-cv-
2   FOREST LABORATORIES, LLC v. SIGMAPHARM LABORATORIES,
                                                    LLC


01266-SLR-SRF, 1:14-cv-01504-SLR-SRF, 1:15-cv-00158-
SLR, 1:15-cv-00430-SLR, Judge Sue L. Robinson.
                ______________________

                Decided: March 14, 2019
                ______________________

    HOWARD WARREN LEVINE, Finnegan, Henderson,
Farabow, Garrett & Dunner, LLP, Washington, DC, ar-
gued for plaintiffs-cross-appellants. Also represented by
JONATHAN ROBERT DAVIES, SANYA SUKDUANG; CHARLES E.
LIPSEY, Reston, VA.

   ANTHONY R. FRIEDMAN, The Simon Law Firm, P.C., St.
Louis, MO, argued for defendant-appellee. Also repre-
sented by ANTHONY G. SIMON.

CLIFFORD KATZ, Kelley Drye & Warren, LLP, New York,
NY, argued for all defendants-appellants. Defendant-ap-
pellant Breckenridge Pharmaceutical Inc. also represented
by MALAVIKA RAO.

    IMRON T. ALY, Schiff Hardin LLP, Chicago, IL, for de-
fendants-appellants Hikma Pharmaceuticals LLC, Hikma
Pharmaceuticals PLC, Hikma Pharmaceuticals USA Inc.
Also represented by JOEL M. WALLACE.

   KSENIA TAKHISTOVA, Hunton Andrews Kurth LLP,
New York, NY, for defendants-appellants Alembic Phar-
maceuticals Ltd., Alembic Global Holding S.A., Alembic
Pharmaceuticals Inc.

    MICHAEL R. DZWONCZYK, Sughrue Mion PLLC, Wash-
ington, DC, for defendants-appellants Amneal Pharmaceu-
ticals LLC, Amneal Pharmaceuticals of New York LLC,
Amneal Pharmaceuticals Co. India Pvt. Ltd.
                  ______________________
FOREST LABORATORIES, LLC v. SIGMAPHARM LABORATORIES,       3
LLC


   Before PROST, Chief Judge, DYK and MOORE, Circuit
                        Judges.
MOORE, Circuit Judge.
    Sigmapharm Laboratories, LLC, (“Sigmapharm”),
Hikma Pharmaceuticals LLC, Hikma Pharmaceuticals
PLC, Hikma Pharmaceuticals USA Inc., (collectively,
“Hikma”), Breckenridge Pharmaceuticals Inc. (“Brecken-
ridge”), Alembic Pharmaceuticals Ltd., Alembic Global
Holdings S.A., Alembic Pharmaceuticals Inc., (collectively,
“Alembic”), Amneal Pharmaceuticals LLC, and Amneal
Pharmaceuticals Co. India Pvt. Ltd. (collectively “Amneal”)
are drug manufacturers who filed Abbreviated New Drug
Applications with the Food and Drug Administration seek-
ing to market generic versions of Saphris, a drug product
sold by Forest Laboratories, LLC. Saphris is a sublingually
administered, atypical antipsychotic containing asenapine
maleate.
    Forest sued for patent infringement, asserting that Ap-
pellants’ proposed generic products would infringe claims
1–2, 4–6, and 9–10 of U.S. Patent No. 5,763,476. The par-
ties have stipulated that the validity of claims 2, 5, and 6
rises and falls with that of claim 1, and the validity of
claims 9 and 10 rises and falls with that of claim 4. Forest,
Breckenridge, and Alembic have further stipulated that in-
fringement of claims 9 and 10 rises and falls with that of
claim 4. Claims 1 and 4 recite:
    1. A pharmaceutical composition comprising as a
    medicinally active compound: trans-5-chloro-2-me-
    thyl-2,3,3a, 12b-tetrahydro-1H-dibenz[2,3:6,7]ox-
    epino[4,5-c]pyrrole    or    a    pharmaceutically
    acceptable salt thereof; wherein the composition is
    a solid composition and disintegrates within 30 sec-
    onds in water at 37° C.
    4. A method for treating tension, excitation, anxi-
    ety, and psychotic and schizophrenic disorders,
4   FOREST LABORATORIES, LLC v. SIGMAPHARM LABORATORIES,
                                                    LLC


    comprising administering sublingually or buccally
    an effective amount of a pharmaceutical composi-
    tion comprising trans-5-chloro-2-methyl-2,3,3a,
    12b-tetrahydro-1H-dibenz[2,3:6,7]oxepino[4,5-
    c]pyrrole or a pharmaceutically acceptable salt
    thereof.
Trans-5-chloro-2-methyl-2,3,3a,12b-tetrahydro-1H-dibenz
[2,3:6,7]oxepino[4,5-c]pyrrole is also known as asenapine.
Forest sells an atypical antipsychotic containing asenapine
maleate under the name Saphris, which was developed by
non-party Organon, another pharmaceutical company.
Asenapine was originally developed as a conventional oral
tablet. Conventional oral tablets are swallowed and enter
into the digestive system before being metabolized. In con-
trast, Saphris is administered sublingually, meaning the
formulation is placed under the tongue, where it dissolves.
Buccal administration is similar, but in the cheek cavity.
     Following a bench trial, the district court held Appel-
lants had not established claims 1–2, 4–6, and 9–10 to be
invalid and held Forest had not established infringement
of claims 4, 9, and 10 as to Alembic and Breckenridge. Ap-
pellants appeal the district court’s construction of claim 1
and its determination that the claims have not been estab-
lished to be invalid. Forest cross-appeals, arguing the dis-
trict court’s finding that Breckenridge and Alembic do not
infringe claim 4 was clearly erroneous. We have jurisdic-
tion under 28 U.S.C. § 1295(a)(1). We vacate and remand
the district court’s validity determination, and we vacate
and remand for it to reconsider infringement under a cor-
rected claim construction.
                       DISCUSSION
                I. Construction of Claim 1
    While claim 4 is expressly limited to sublingual or buc-
cal formulations of asenapine, claim 1 is not and instead
FOREST LABORATORIES, LLC v. SIGMAPHARM LABORATORIES,        5
LLC


states that “the composition is a solid composition and dis-
integrates within 30 seconds in water at 37° C.” The dis-
trict court nevertheless construed claim 1 to be limited to
buccal and sublingual formulations. Appellants argue the
district court erred in construing claim 1 this way. We re-
view a district court’s ultimate claim construction and its
interpretations of intrinsic evidence de novo and any sub-
sidiary fact findings about extrinsic evidence for clear er-
ror. CardSoft, (Assignment for the Benefit of Creditors),
LLC v. VeriFone, Inc., 807 F.3d 1346, 1348 (Fed. Cir. 2015).
    We see no error in the district court’s construction. Alt-
hough claim 1 does not expressly refer to buccal or sublin-
gual administration, the claims “must be read in view of
the specification, of which they are a part.” Phillips v.
AWH Corp., 415 F.3d 1303, 1315 (Fed. Cir. 2005) (en banc)
(quoting Markman v. Westview Instruments, Inc., 52 F.3d
967, 979 (Fed. Cir. 1995)). “When a patent . . . describes
the features of the ‘present invention’ as a whole, this de-
scription limits the scope of the invention.” Verizon Servs.
Corp. v. Vonage Holdings Corp., 503 F.3d 1295, 1308 (Fed.
Cir. 2007). Here, the ’476 patent states “[t]he invention re-
lates to a sublingual or buccal pharmaceutical composi-
tion,” ’476 patent at 1:6–7, strongly supporting the district
court’s construction. See also id. at 1:33–36. That con-
struction is further supported by additional language in
the specification, which explains the benefits of sublingual
and buccal treatment over the prior art. Id. at 1:33–34
(“The invention therefore relates to a sublingual or buccal
pharmaceutical composition . . . .”). The patent is also ex-
pressly titled “Sublingual or Buccal Pharmaceutical Com-
position.” See, e.g., UltimatePointer, L.L.C. v. Nintendo
Co., 816 F.3d 816, 823 (Fed. Cir. 2016) (using patent title
to inform claim construction). Additionally, the claim lan-
guage “disintegrates within 30 seconds in water at 37° C”
appears in the ’476 patent as the definition of “[r]apid dis-
integration.” ’476 patent at 1:59–61. The specification
states that “[p]referred pharmaceutical compositions are
6   FOREST LABORATORIES, LLC v. SIGMAPHARM LABORATORIES,
                                                    LLC


solid pharmaceutical compositions which rapidly disinte-
grate in the mouth of a subject, upon insertion into the buc-
cal pouch or upon placement under the tongue.” Id. at
1:56–59. This strongly suggests that the language “the
composition is a solid composition and disintegrates within
30 seconds in water at 37° C” was meant to limit the claim
to buccal and sublingual formulations.
    Appellants suggest that this improperly reads a
method step into the claim by requiring a particular
method of administration, namely sublingual or buccal.
The specification, however, repeatedly uses “sublingual or
buccal” to modify “composition,” indicating that these are
properties of the composition itself. See, e.g., Id. at 1:6–7.
    We have considered Appellants’ remaining arguments
as to claim construction and find them unpersuasive. 1
Given the claim language and the language in the specifi-
cation, we hold the district court properly construed
claim 1 to be limited to buccal and sublingual formulations.
We do not, therefore, reach Appellants’ validity challenges
based on its proposed alternative construction.
                      II. Obviousness
    Following a bench trial, the district court concluded
claims 1 and 4 would not have been obvious. While it is
undisputed that both oral formulations of asenapine and
sublingual formulations of other drugs were known in the


    1   Although Appellants now argue this construction
renders the claim indefinite, this argument has been
waived. The section of their post-trial briefing in which
Appellants argue they raised this issue below nowhere
mentions indefiniteness. J.A. 3325–35. Instead, it only
mentions § 112, the statutory basis for the definiteness
challenge, in a parenthetical to the fourth case cited in a
string citation. Id. This is insufficient to preserve the ar-
gument.
FOREST LABORATORIES, LLC v. SIGMAPHARM LABORATORIES,        7
LLC


prior art, the district court found that there was no moti-
vation in the art to develop sublingual or buccal formula-
tions of asenapine.       It found the resolution of the
cardiotoxic effects by sublingual administration was an un-
expected result. It found sublingual administration met a
long-felt need for a safe, effective, and tolerable atypical
antipsychotic useful to treat schizophrenia and mania.
    Obviousness is a question of law with underlying facts.
Par Pharm. Inc. v. TWI Pharm., Inc., 773 F.3d 1186, 1193
(Fed. Cir. 2014). After a bench trial, we review the district
court’s conclusion of obviousness de novo and the underly-
ing factual findings for clear error. Id. at 1194.
                 A. Motivation to Combine
    The district court found Appellants had not established
that there was a motivation to combine asenapine maleate
into a sublingual or buccal form, and even if there were a
motivation to combine, a skilled artisan would not have
had a reasonable expectation that it would work. Whether
there was a motivation to combine prior art references is a
question of fact. Arctic Cat Inc. v. Bombardier Recreational
Prods. Inc., 876 F.3d 1350, 1359 (Fed. Cir. 2017). We re-
view for clear error.
     An invention is not obvious simply because all of the
claimed limitations were known in the prior art at the time
of the invention. Instead, we ask “whether there is a rea-
son, suggestion, or motivation in the prior art that would
lead one of ordinary skill in the art to combine the refer-
ences, and that would also suggest a reasonable likelihood
of success.” Smiths Indus. Med. Sys., Inc. v. Vital Signs,
Inc., 183 F.3d 1347, 1356 (Fed. Cir. 1999). The motivation
“can be found explicitly or implicitly in the prior art refer-
ences themselves, in market forces, in design incentives, or
in ‘any need or problem known in the field of endeavor at
the time of invention and addressed by the patent.’” Arctic
Cat, 876 F.3d at 1359 (quoting KSR Int’l Co. v. Teleflex Inc.,
550 U.S. 398, 420–21 (2007)).
8   FOREST LABORATORIES, LLC v. SIGMAPHARM LABORATORIES,
                                                    LLC


    At trial, Appellants’ primary and dominant argument
as to motivation to combine was an alleged bioavailability
concern with orally administered asenapine. The district
court extensively considered this argument and rejected it.
On appeal, Appellants have dispensed with their bioavail-
ability argument and instead focus on two other claimed
motivations. First, they argue an ordinarily skilled artisan
would have been motivated to administer asenapine male-
ate sublingually or buccally to address known compliance
concerns. Second, they argue an ordinarily skilled artisan
would have been motivated to administer asenapine male-
ate sublingually or buccally to obtain more treatment op-
tions.
    Appellants argue that an ordinarily skilled artisan
would have been motivated to administer asenapine male-
ate sublingually or buccally to address compliance prob-
lems and swallowing difficulties in special patient
populations. The district court discussed compliance con-
cerns and, citing testimony from Forest’s expert witness
Dr. McIntyre, explained that “clinicians with experience in
treating schizophrenic patients understand that sublin-
gual dosage forms are more burdensome to schizophrenic
patients in that they require the patient to hold the dosage
form in the mouth under the tongue for a period of time,
and also require that the patient refrain from drinking or
swallowing for a period of time.” J.A. 73 (citing J.A. 592–
93). The court further explained that Appellants’ “own ex-
pert clinician, Dr. Hollander, agreed that sublingual ad-
ministration would not improve patient compliance.”
J.A. 73 (citing J.A. 442–43). Summarizing testimony, how-
ever, is not a clear finding. Our review would be aided by
an express finding regarding whether compliance concerns
regarding patients with swallowing difficulties would pro-
vide a motivation to combine.
    Turning to Appellants’ second claimed motivation, we
hold that the district court did not clearly err in rejecting
Appellants’ contention that the benefits of having multiple
FOREST LABORATORIES, LLC v. SIGMAPHARM LABORATORIES,        9
LLC


treatment options available would provide a motivation to
combine. In assessing whether there was a long-felt need,
the district court found that “skilled artisans recognized
the benefit of having multiple treatment options.” J.A. 76.
Appellants further argue that their expert Dr. Hollander
testified that there was a need for additional treatment op-
tions because no single product is appropriate for all pa-
tient populations and that in 1994, many antipsychotics
were on the market in multiple forms. The district court
did not clearly err, however, in concluding that a generic
need for more antipsychotic treatment options did not pro-
vide a motivation to combine these particular prior art ele-
ments.
    Appellants argue the district court ignored general
suggestions in the prior art indicating a growing interest
in sublingual and buccal formulations at the time of filing.
The district court was presented with a variety of documen-
tary evidence and testimony as to the state of the prior art.
We see no clear error in its weighing of this evidence.
     Finally, Appellants suggest that the district court erred
in treating the claimed invention as providing a solution to
an unrecognized problem in the art. We have recognized
that where a problem was not known in the art, the solu-
tion to that problem may not be obvious, because “ordinary
artisans would not have thought to try at all because they
would not have recognized the problem.” Leo Pharm.
Prods., Ltd. v. Rea, 726 F.3d 1346, 1357 (Fed. Cir. 2013).
    The district court characterized the inventors’ discov-
ery as a recognition of an unknown problem in the art in
conjunction with the discovery of the solution to that prob-
lem. J.A. 69–70. It found that the Organon scientists dis-
covered a “previously unknown” problem and developed the
claimed sublingual dosage forms as a solution to that prob-
lem. Specifically, it found that during early clinical studies
Organon discovered intravenous and oral administration of
10 FOREST LABORATORIES, LLC v. SIGMAPHARM LABORATORIES,
                                                         LLC


asenapine resulted in severe cardiotoxic events. As a re-
sult, those studies were terminated prior to completion.
The district court found, however, that during subsequent
testing on beagles, while there was “a clear trend of in-
creased heart effects with an oral tablet,” “no such trend
was observed with the sublingual forms.” J.A. 44–45. The
district court found that while Organon became aware of
these problems, “[t]here was nothing in the prior art that
would have indicated that the oral tablet had problems.”
J.A. 68.
     The district court further held that the solution Orga-
non developed to address the cardiotoxic effect was also
non-obvious. It found that Organon’s data indicated that
the cardiotoxic effect was likely caused by asenapine itself.
J.A. 69. During conventional oral administration, asenap-
ine undergoes first-pass metabolism, which processes the
parent compound asenapine into metabolites. J.A. 69. In
contrast, sublingual administration increases the amount
of the parent compound by circumventing first-pass metab-
olism. J.A. 69. The district court held, therefore, that it
would not have been predictable or expected that sublin-
gual administration would provide a solution to the prob-
lem of cardiotoxic effects. J.A. 69–70.
    Appellants object to this reasoning, arguing that the
only reason the cardiotoxicity issue was not publicly known
was because Organon concealed and misrepresented the
events suffered by patients in clinical studies when it re-
ported the results of those studies. While the actions al-
leged may raise a variety of concerns, we do not see how
they affect the district court’s obviousness analysis. Ulti-
mately, we see no clear error in the district court’s consid-
eration of the unknown nature of the problem solved by the
inventors and the factors that would teach away from their
solution.
    We have considered Appellants’ remaining arguments
as to motivation to combine and find them unpersuasive.
FOREST LABORATORIES, LLC v. SIGMAPHARM LABORATORIES,      11
LLC


However, in light of the district court’s failure to make an
express finding as to whether compliance concerns for pa-
tients with trouble swallowing would provide a motivation
to combine, we remand for the district court to address this
question.
                    B. Long-Felt Need
    “Evidence of a long felt but unresolved need tends to
show non-obviousness because it is reasonable to infer that
the need would have not persisted had the solution been
obvious.” WBIP, LLC v. Kohler Co., 829 F.3d 1317, 1332
(Fed. Cir. 2016). Whether or not such a long-felt need ex-
isted is a question of fact. Bristol-Myers Squibb Co. v. Teva
Pharm. USA, Inc., 752 F.3d 967, 978 (Fed. Cir. 2014).
    The district court found that at the time of the inven-
tion, there was a long-felt, but unmet, need for “a safe, ef-
fective, and tolerable atypical antipsychotic useful to treat
schizophrenia and mania.” J.A. 76. In doing so, it found
that prior to 1994, “typical antipsychotics were the primary
therapeutic options for treating schizophrenia and mania.”
J.A. 75. It noted, however, that typical antipsychotics “pos-
sessed debilitating side effects” and “a significant number
of patients did not respond to treatment.” J.A. 75. As of
1994, there were also two atypical antipsychotics available.
J.A. 75. One “require[d] constant blood monitoring” and
had a “life-threatening side effect.” J.A. 75. The other had
a variety of side effects that resulted in a discontinuation
rate of around 74%. J.A. 75–76. Accordingly, the district
court found that ordinarily skilled artisans “recognized the
need for additional antipsychotic drugs” with improved
side effect profiles. J.A. 76. It further found asenapine met
this profile. J.A. 76.
    Appellants point to evidence that they argue indicates
the claimed invention did not satisfy a long-felt but unmet
need. Specifically, they argue there were a variety of anti-
psychotic drugs available at the time of the invention, there
12 FOREST LABORATORIES, LLC v. SIGMAPHARM LABORATORIES,
                                                          LLC


is evidence that physicians did not switch treatment pref-
erences for patients with schizophrenia when Saphris en-
tered the market, and there is evidence that Saphris did
not have better efficacy or compliance than other antipsy-
chotics available in 1994. They further argue Saphris itself
has many side effects and a high discontinuation rate.
They argue the district court’s comparison of Saphris with
the two other atypical antipsychotics, clozapine and risper-
idone, ignored evidence that clozapine treated the negative
symptoms of schizophrenia, which Saphris does not; that
both drugs were superior to Saphris in terms of efficacy and
side effects; and that both drugs had much lower all-cause
discontinuation rates than Saphris.
    In reviewing the district court’s fact findings, we do not
ask whether evidence could have supported the opposing
view, only whether the district court clearly erred. Here it
did not. Although there were a variety of existing antipsy-
chotics, they had debilitating negative side effects, which
evidence indicates are reduced in Saphris. See, e.g., J.A.
599, 603. While this may not be a particularly strong
demonstration of long-felt need, the district court did not
clearly err in finding it weighs in favor of non-obviousness.
                  C. Unexpected Results
    A showing of unexpected results can support a conclu-
sion of non-obviousness. See United States v. Adams, 383
U.S. 39, 51–52 (1966). In considering unexpected results,
courts ask whether “the claimed invention exhibits some
superior property or advantage that a person of ordinary
skill in the relevant art would have found surprising or un-
expected.” In re Soni, 54 F.3d 746, 750 (Fed. Cir. 1995).
While we have permitted evidence from after the patent is
granted to be considered in assessing whether there are
unexpected results, Knoll Pharm. Co. v. Teva Pharm. USA,
Inc., 367 F.3d 1381, 1385 (Fed. Cir. 2004), the results must
be “unexpected by one of ordinary skill in the art at the
FOREST LABORATORIES, LLC v. SIGMAPHARM LABORATORIES,       13
LLC


time of [the] application,” In re Geisler, 116 F.3d 1465, 1470
(Fed. Cir. 1997).
     Here, the district court found it was “surprising and
unexpected” that the claimed “sublingual route of admin-
istration successfully resolved the serious cardiotoxic event
reported in the ’476 patent.” J.A. 74. However, as the dis-
trict court found, there was nothing in the prior art that
indicated cardiotoxic problems existed with other routes of
administration. J.A. 68. We explained in Soni that the
reason why unexpected results support a conclusion of non-
obviousness is simple: “that which would have been sur-
prising to a person of ordinary skill in a particular art
would not have been obvious.” 54 F.3d at 750. At the time
of the claimed invention, a person of ordinary skill could
not have been surprised that the sublingual route of ad-
ministration did not result in cardiotoxic effects because
the person of ordinary skill would not have been aware that
other routes of administration do result in cardiotoxic ef-
fects. The district court, therefore, erred in its analysis of
unexpected results.
                    D. Legal Conclusion
    We review the ultimate question of obviousness de
novo. Arctic Cat, 876 F.3d at 1365. Given the lack of an
express finding that compliance concerns with patients
who have trouble swallowing would not provide a motiva-
tion to combine, we vacate the district court’s judgment of
non-obviousness and remand.
                  III. Written Description
    Section 112 of the Patent Act requires the specification
contain “a written description of the invention.” The writ-
ten description requirement is met when “the disclosure of
the application relied upon reasonably conveys to those
skilled in the art that the inventor had possession of the
claimed subject matter as of the filing date.” Ariad Pharm.,
Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1351 (Fed. Cir. 2010)
14 FOREST LABORATORIES, LLC v. SIGMAPHARM LABORATORIES,
                                                          LLC


(en banc). Written description is a question of fact, which
we review for clear error. Pozen Inc. v. Par Pharm., Inc.,
696 F.3d 1151, 1166 (Fed. Cir. 2012).
    Appellants argue the specification fails to describe
asenapine free base in a rapidly disintegrating, sublingual,
or buccal solid composition. Both claims 1 and 4 require a
“pharmaceutical composition” containing “trans-5-chloro-
2-methyl-2,3,3a,12b-tetrahydro-1H-dibenz[2,3:6,7]oxepino
[4,5-c]pyrrole or a pharmaceutically acceptable salt
thereof.” The parties’ experts agree that “trans-5-chloro-2-
methyl-2,3,3a, 12b-tetrahydro-1H-dibenz[2,3:6,7]oxepino
[4,5-c]pyrrole or a pharmaceutically acceptable” is the free
base of asenapine.
    The district court’s finding that the specification con-
tains sufficient written description support for claims 1 and
4 was not clearly erroneous. Appellants’ expert witness
Dr. Gould acknowledged asenapine free base was known in
the art. The specification repeatedly refers to pharmaceu-
tical compositions containing asenapine free base. E.g.,
’476 patent at 1:33–36. While Appellants cite evidence that
the properties of asenapine free base make it unsuitable for
use in pharmaceutical development, the district court did
not clearly err in finding that Appellants had not estab-
lished invalidity for lack of written description by clear and
convincing evidence.
               IV. Infringement of Claim 4
    The district court found Breckenridge and Alembic do
not infringe claim 4 directly, indirectly, or under the doc-
trine of equivalents. [A82] Breckenridge and Alembic’s
proposed generic products are indicated for the treatment
of “manic episodes” associated with bipolar I disorder.
Claim 4 is directed to “a method for treating tension, exci-
tation, anxiety, and psychotic and schizophrenic disor-
ders.” The court construed claim 4 to not cover the
treatment of bipolar disorders. J.A. 57. We review the ul-
timate claim construction de novo and any subsidiary fact
FOREST LABORATORIES, LLC v. SIGMAPHARM LABORATORIES,       15
LLC


findings about extrinsic evidence for clear error. CardSoft,
807 F.3d at 1348. Because we hold that the district court
erred in its claim construction, we vacate and remand as to
infringement of claim 4.
     The claim language and the specification indicate that
“excitation” refers to a symptom rather than a “disorder.”
The use of the conjunction “and” before “psychotic and
schizophrenic disorders” indicates that “psychotic and
schizophrenic disorders” is a distinct item on the list, and
that unlike the terms “psychotic” and “schizophrenic,” the
words “tension,” “excitation,” and “anxiety” are not describ-
ing “disorders.” This is consistent with how “excitation” is
used elsewhere in the specification. ’476 patent at 5:55–58.
Moreover, experts for both parties agree that there is no
such thing as an “excitation disorder,” J.A. 218, 349, fur-
ther indicating the claim covers treatment of the symptom
“excitation” rather than treatment of an “excitation disor-
der.” Although excitation may be a symptom of bipolar I
disorder, the district court nevertheless carved bipolar I
disorder out of its construction because it concluded that
the “language of the ’476 patent is directed to ‘diseases’ and
‘disorders,’ not to symptoms of such.” J.A. 50. This mis-
reads the plain language of the claims and specification.
    Because the district court erred in treating “excitation”
as being limited to “excitation disorders,” we vacate its
finding of non-infringement. We construe “excitation” to
refer to a symptom and remand for the district court to as-
sess infringement in light of this construction.
                        CONCLUSION
    We vacate the district court’s judgment that Claims 1
and 4 are not invalid and remand for it to consider the lim-
ited question of whether compliance concerns with patients
who have trouble swallowing would provide a motivation
to combine and its impact on the obviousness analysis. We
vacate its judgment of non-infringement of claims 4, 9, and
10 as to Breckenridge and Alembic and remand for the
16 FOREST LABORATORIES, LLC v. SIGMAPHARM LABORATORIES,
                                                   LLC


court to consider whether Breckenridge and Alembic in-
fringe under our revised construction.
               VACATED AND REMANDED
                        COSTS
   No costs.
