  United States Court of Appeals
      for the Federal Circuit
                ______________________

 INTENDIS GMBH, INTRASERV GMBH & CO. KG,
BAYER HEALTHCARE PHARMACEUTICALS INC.,
             Plaintiffs-Appellees

                           v.

   GLENMARK PHARMACEUTICALS INC., USA,
     GLENMARK PHARMACEUTICALS LTD.,
            Defendants-Appellants
           ______________________

                      2015-1902
                ______________________

    Appeal from the United States District Court for the
District of Delaware in No. 1:13-cv-00421-SLR, Judge Sue
L. Robinson.
                 ______________________

                Decided: May 16, 2016
                ______________________

   BRADFORD J. BADKE, Sidley Austin LLP, New York,
NY, argued for plaintiffs-appellees. Also represented by
SONA DE.

    WILLIAM M. JAY, Goodwin Procter LLP, Washington,
DC, argued for defendants-appellants. Also represented
by BRIAN TIMOTHY BURGESS; ELIZABETH HOLLAND, LINNEA
P. CIPRIANO, HUIYA WU, New York, NY; DAVID ZIMMER,
San Francisco, CA.
                ______________________
2        INTENDIS GMBH   v. GLENMARK PHARMACEUTICALS INC.




    Before PROST, Chief Judge, MOORE and TARANTO, Cir-
                      cuit Judges.
MOORE, Circuit Judge.
     This case arises under the Hatch–Waxman Act, 1 and
involves Glenmark Pharmaceuticals Ltd. and Glenmark
Pharmaceuticals Inc., USA’s (collectively, “Glenmark”) 2
proposed generic version of Finacea® Gel, a topical medi-
cation for various skin disorders. Glenmark appeals the
United States District Court for the District of Delaware’s
final judgment entered in favor of Intendis GmbH, In-
traserv GmbH & Co. KG, and Bayer HealthCare Pharma-
ceuticals Inc. (collectively, “Appellees”). For the reasons
set forth below, we affirm.
                      BACKGROUND
     Appellee Bayer HealthCare Pharmaceuticals Inc.
holds approved New Drug Application (“NDA”) No. 21470
for Finacea® Gel, which contains azelaic acid as the
therapeutically active ingredient in a concentration of
15% by weight and is indicated for the topical treatment
of inflammatory papules and pustules of mild to moderate
rosacea. Finacea® Gel’s inactive ingredients, known as
excipients, include triglycerides and lecithin. Finacea®
Gel is manufactured in the form of a “hydrogel,” which the


    1   The Hatch–Waxman Act is the name commonly
used to refer to the Drug Price Competition and Patent
Term Restoration Act of 1984, Pub. L. No. 98–417, 98
Stat. 1585 (1984) (codified in relevant part at 21 U.S.C. §
355), as amended, which governs the Food and Drug
Administration’s approval of new and generic drugs.
    2   Glenmark Pharmaceuticals Ltd. and Glenmark
Pharmaceuticals Inc., USA were formerly known as
Glenmark Generics Ltd. and Glenmark Generics Inc.,
USA, respectively.
INTENDIS GMBH   v. GLENMARK PHARMACEUTICALS INC.         3



district court construed to mean “a semisolid dosage form
that contains water and a gelling agent to form a gel,
which may contain dispersed particles and/or insoluble
liquids.” Intendis GmbH v. Glenmark Pharm. Ltd., 117 F.
Supp. 3d 549, 567–68 (D. Del. 2015).
    The Food and Drug Administration’s (“FDA”) Ap-
proved Drug Products with Therapeutic Equivalence
Evaluation, commonly known as the Orange Book, lists
U.S. Patent No. 6,534,070 (“the ’070 patent”) as covering
Finacea® Gel. The ’070 patent, entitled “Composition
with Azelaic Acid,” is assigned to Appellee Intraserv
GmbH & Co. and exclusively licensed to Appellee Intendis
GmbH. The patent issued in March 2003 and claims
priority to a provisional application filed on February 12,
1998. Sole independent claim 1 of the ’070 patent recites:
       1. A composition that comprises:
       (i) azelaic acid as a therapeutically active
           ingredient in a concentration of 5 to 20%
           by weight,
       (iii) at least one triacylglyceride 3 in a con-
           centration of 0.5 to 5% by weight,
       (iv) propylene glycol, and
       (v) at least one polysorbate, in an aqueous
          phase that further comprises water and
          salts, and the composition further com-
          prises
       (ii) at least one polyacrylic acid, and
       (vi) lecithin,




   3    The parties agree that the claim term “triacyl-
glyceride” means “triglyceride.”
4        INTENDIS GMBH   v. GLENMARK PHARMACEUTICALS INC.



          wherein the composition is in the form
          of a hydrogel.
’070 patent, col. 6, lines 28–39 (emphases added).
    Glenmark Pharmaceuticals Ltd. submitted an Abbre-
viated New Drug Application (“ANDA”) to the FDA seek-
ing to market a generic version of Finacea® Gel. The
submission included a paragraph IV certification pursu-
ant to 21 U.S.C. § 355(j)(2)(A)(vii)(IV) asserting that the
’070 patent is invalid and not infringed. Unlike Finacea®
Gel, the proposed generic product substituted isopropyl
myristate for the claimed triglyceride and lecithin. Pur-
suant to 21 U.S.C. § 505(j)(2)(B)(ii), Glenmark Pharma-
ceuticals Inc., USA informed Appellees that an ANDA had
been filed. In response, Appellees filed a complaint
against Glenmark in the United States District Court for
the District of Delaware, alleging that Glenmark’s sub-
mission of the ANDA infringed the ’070 patent under 35
U.S.C. § 271(e)(2)(A).
    The district court held a Markman hearing on Janu-
ary 21, 2015, and a five-day bench trial from February 5–
11, 2015 on the issues of infringement and validity. On
July 27, 2015, the district court issued an opinion conclud-
ing that claims 1–12 of the ’070 patent were infringed
under the doctrine of equivalents and not invalid.
     With respect to infringement, the central dispute was
whether isopropyl myristate in Glenmark’s generic prod-
uct met the claim elements triglyceride and lecithin under
the doctrine of equivalents. The district court found that
it did, relying on the function-way-result test. The dis-
trict court rejected Glenmark’s arguments that infringe-
ment under the doctrine of equivalents (i) would
encompass the prior art and (ii) was barred by prosecu-
tion history estoppel.
   With respect to validity, the district court found that
none of the prior art references raised by Glenmark
INTENDIS GMBH   v. GLENMARK PHARMACEUTICALS INC.          5



disclosed every element of independent claim 1 and
rejected Glenmark’s argument that the claims would have
been obvious. Prior to Finacea® Gel, Bayer marketed and
sold a topical 20% azelaic acid cream known as Ski-
noren®, which is prior art to the ’070 patent. The district
court agreed with Glenmark that a person of ordinary
skill in the art would pursue a hydrogel formulation of
azelaic acid because the Skinoren® formulation had
undesirable qualities such as phase separation of the
emulsion, whitening effect, and spreadability problems.
However, the district court determined that Glenmark
failed to show by clear and convincing evidence that a
person of ordinary skill would have been motivated to
combine the prior art references in a manner that would
render claim 1 of the ’070 patent obvious. It determined
that even if Glenmark had, Glenmark failed to show a
reasonable expectation of success in making such combi-
nation. Finally, the district court found that the objective
indicia of nonobviousness, namely, unexpected results of
the claimed formulations and commercial success of
Finacea® Gel, weighed in favor of nonobviousness.
     On August 14, 2015, the district court entered a final
judgment in favor of Appellees and directed the FDA not
to approve Glenmark’s ANDA until after the November
18, 2018, expiration of the ’070 patent. This appeal
followed.
                        DISCUSSION
    On appeal, Glenmark argues that (i) the district court
erred in its application of the function prong of the func-
tion-way-result test for infringement under the doctrine of
equivalents, (ii) infringement under the doctrine of equiv-
alents would encompass the prior art, (iii) Appellees
expressly disavowed and disclaimed a formulation with-
out lecithin, and (iv) the district court erred in its obvi-
ousness analysis. We address each argument in turn.
    I. Infringement Under the Doctrine of Equivalents
6         INTENDIS GMBH   v. GLENMARK PHARMACEUTICALS INC.



    Infringement under the doctrine of equivalents is a
question of fact that we review for clear error following a
bench trial. Allergan, Inc. v. Sandoz Inc., 796 F.3d 1293,
1311 (Fed. Cir. 2015). Even when an accused product
does not meet each and every claim element literally, it
may nevertheless be found to infringe the claim “if there
is ‘equivalence’ between the elements of the accused
product or process and the claimed elements of the pa-
tented invention.” Warner-Jenkinson Co. v. Hilton Davis
Chem. Co., 520 U.S. 17, 21 (1997) (quoting Graver Tank &
Mfg. Co. v. Linde Air Prods. Co., 339 U.S. 605, 609
(1950)). One way to show equivalence is by showing on an
element-by-element basis that “the accused product
performs substantially the same function in substantially
the same way with substantially the same result as each
claim limitation of the patented product,” often referred to
as the function-way-result test. Crown Packaging Tech.,
Inc. v. Rexam Beverage Can Co., 559 F.3d 1308, 1312
(Fed. Cir. 2009). Each prong of the function-way-result
test is a factual determination. In this case, neither party
objects to employing the function-way-result test as a
means to determine equivalency of these chemical com-
pounds.
     Glenmark’s argument on appeal is limited to the dis-
trict court’s determination that Glenmark’s isopropyl
myristate performed substantially the same function as
the claimed triglyceride and lecithin. We review the
district court’s determination that they perform substan-
tially the same function, a question of fact, for clear error.
Biovail Corp. Int’l v. Andrx Pharm., Inc., 239 F.3d 1297,
1300 (Fed. Cir. 2001). To be clear, we are not presented
with the issue of the substantiality of the differences
between the chemical structures of isopropyl myristate,
triglyceride, and lecithin. This appeal is limited to
whether the district court clearly erred when it deter-
mined that triglyceride and lecithin function as penetra-
tion enhancers in the claimed compounds.
INTENDIS GMBH   v. GLENMARK PHARMACEUTICALS INC.           7



     Glenmark’s non-infringement argument was based on
the claim elements triglyceride and lecithin (collectively,
“claimed excipients”), which are recited in the sole inde-
pendent claim 1. Even though Glenmark’s generic prod-
uct did not physically contain triglyceride or lecithin, the
district court found that the claimed excipients were met
under the doctrine of equivalents. First, the court found
that isopropyl myristate in Glenmark’s generic product
(“Glenmark’s excipient”) performs substantially the same
function as the claimed excipients—namely, enhancing
azelaic acid’s penetration of the skin. It reasoned that
several experts testified that the claimed excipients could
act as penetration enhancers and that “nothing in the
record” indicated they could not. It also reasoned that
Glenmark’s ANDA included repeated statements that
both Glenmark’s excipient and the claimed excipients
function as penetration enhancers. It noted that Glen-
mark “should not be permitted to liken their product to
the claimed composition to support their bid for FDA
approval, yet avoid the consequences of such a comparison
for purposes of infringement.” Intendis, 117 F. Supp. 3d
at 573. Second, the court found that Glenmark’s excipient
performed in substantially the same way as the claimed
excipients—namely, by disrupting the lipids in the skin’s
outermost layer, known as the stratum corneum. It based
its finding on testimony by various experts, as supported
by scientific literature. Third, the court found that Glen-
mark’s excipient obtained substantially the same result
as the claimed excipients—namely, a therapeutically
effective azelaic acid composition that is able to penetrate
the skin in order to deliver the active ingredient. It relied
on data from the ’070 patent, Glenmark’s own patent
application, a skin penetration study, and a clinical trial.
    On appeal, Glenmark argues that the district court
erred in its finding regarding the function prong because
Appellees failed to prove that the claimed excipients
function as penetration enhancers in the claimed composi-
8        INTENDIS GMBH   v. GLENMARK PHARMACEUTICALS INC.



tion. It argues that “[t]he ’070 patent itself is silent on
the question of whether lecithins or triglycerides function
as penetration enhancers.” Intendis, 117 F. Supp. 3d at
572. According to Glenmark, this absence of support in
the patent itself for the notion that the claimed excipients
function as penetration enhancers is fatal to Appellees’
infringement case. Glenmark argues that Appellees’
theory is also contradicted by evidence outside the patent.
It points to Appellees’ FDA filings and development
reports as such examples, which identified the claimed
lecithin and triglyceride as an emulsifier and an emol-
lient, respectively. It argues that not a single literature
reference in evidence identified lecithin or triglyceride as
a penetration enhancer, and Appellees’ expert testimony
was rejected by the district court. According to Glenmark,
the district court justified its finding that the claimed
excipients function as penetration enhancers on the basis
that the evidence did not exclude that possibility, despite
the lack of any affirmative evidence.
     We see no clear error in the district court’s finding of
infringement under the doctrine of equivalents. As an
initial matter, we disagree that the lack of disclosure of
the claimed excipients as penetration enhancers in the
’070 patent is fatal to Appellees’ infringement case. We
have never held that a patent must spell out a claim
element’s function, way, and result in order for the doc-
trine of equivalents to apply as to that element. To the
contrary, we have held that “[w]hen the claims and speci-
fication of a patent are silent as to the result of a claim
limitation, . . . we should turn to the ordinary skilled
artisan.” Stumbo v. Eastman Outdoors, Inc., 508 F.3d
1358, 1365 (Fed. Cir. 2007).
    Certainly, a patent’s disclosure is relevant and can at
times be dispositive of the function. Glenmark is correct
that the proper analysis focuses on the claimed element’s
function in the claimed composition, not a function that
element could perform in the abstract divorced from the
INTENDIS GMBH   v. GLENMARK PHARMACEUTICALS INC.           9



claimed composition. But Glenmark is wrong to the
extent that it argues that a determination of the claimed
element’s function is limited to a review of the intrinsic
record. The relevant inquiry is what the claim element’s
function in the claimed composition is to one of skill in the
art, and a fact finder may rely on extrinsic evidence in
making this factual determination. Zenith Labs., Inc. v.
Bristol-Myers Squibb Co., 19 F.3d 1418, 1425 (Fed. Cir.
1994).
    Glenmark argues that the district court erred in its
determination that the claimed excipients function as
penetration enhancers in light of the evidence of record.
We see no clear error in this district court fact finding.
Fatal to Glenmark’s argument is its own ANDA submis-
sion to the FDA repeatedly referring to the claimed excip-
ients (triglyceride and lecithin) as penetration enhancers.
For example, Glenmark stated in its filing to the FDA
that “[i]sopropyl myristate was selected as [a] penetration
enhancer instead of lecithin and medium chain triglycer-
ide” under the heading “Selection of penetration enhanc-
er.” J.A. 5865. Glenmark’s repeated statements to the
FDA that the claimed excipients function as penetration
enhancers tend to show that one of skill in the art would
understand the claimed excipients to function as penetra-
tion enhancers. We see no reason why a district court
acting as a fact finder should ignore a party’s representa-
tion to a federal regulatory body that is directly on point.
Based on this record, the district court’s finding regarding
the function of the claimed excipients is not clearly erro-
neous.
    In a strange turn of events, Glenmark argued at oral
argument to this court that its statements in its FDA
submissions about the claimed excipients (triglyceride
and lecithin) functioning as penetration enhancers should
be rejected and cannot be evidence to support the district
court’s finding. It argued that “lecithin and triglycerides
are not known to the art as penetration enhancers” and
10       INTENDIS GMBH   v. GLENMARK PHARMACEUTICALS INC.



that its representation to the FDA that they do function
as penetration enhancers was a “guess” and “wrong.”
Oral Argument at 10:49–13:38, Intendis GmbH v. Glen-
mark Pharm. Inc., No. 2015-1902 (Fed. Cir. Jan. 8, 2016),
available     at     http://oralarguments.cafc.uscourts.gov/
default.aspx?fl=2015-1902.mp3. These seemingly extem-
poraneous arguments do not persuade us that there is
clear error in the district court’s decision that isopropyl
myristate in Glenmark’s generic product and the claimed
triglyceride and lecithin perform substantially the same
function. No such arguments were made by Glenmark in
any of its briefing to this court. And when asked whether
Glenmark had notified the FDA of these purported inac-
curate representations to the FDA, Glenmark’s counsel
was unaware of such notification. Id. at 11:53–12:25.
   The district court did not clearly err in its findings re-
garding the doctrine of equivalents.
              II. Encompassing the Prior Art
    A patentee may not assert “a scope of equivalency
that would encompass, or ensnare, the prior art.” DePuy
Spine, Inc. v. Medtronic Sofamor Danek, Inc., 567 F.3d
1314, 1322 (Fed. Cir. 2009) (quotation marks omitted).
Even if an accused element meets the function-way-result
test, no equivalent will be found if the scope of equivalen-
cy would capture the prior art. Hypothetical claim analy-
sis is a practical method to determine whether an
equivalent would impermissibly ensnare the prior art.
See Ultra-Tex Surfaces, Inc. v. Hill Bros. Chem. Co., 204
F.3d 1360, 1364 (Fed. Cir. 2000). Hypothetical claim
analysis is a two-step process. The first step is “to con-
struct a hypothetical claim that literally covers the ac-
cused device.” DePuy Spine, 567 F.3d at 1324. Next,
prior art introduced by the accused infringer is assessed
to “determine whether the patentee has carried its burden
of persuading the court that the hypothetical claim is
patentable over the prior art.” Id. at 1325. In short, we
INTENDIS GMBH   v. GLENMARK PHARMACEUTICALS INC.         11



ask if a hypothetical claim can be crafted, which contains
both the literal claim scope and the accused device, with-
out ensnaring the prior art. We review a district court’s
conclusion that a hypothetical claim does not encompass
the prior art de novo and resolution of underlying factual
issues for clear error. Id. at 1324.
     The district court determined that a proper hypothet-
ical claim included the claimed excipients and Glenmark’s
excipient, namely, the hypothetical claim includes isopro-
pyl myristate as an alternative to the claimed triglyceride
and lecithin. Glenmark argued that finding infringement
under the doctrine of equivalents would ensnare a prior
art reference entitled “In vitro permeation of azelaic acid
from viscosized microemulsions” (“Gasco”), which dis-
closed a microemulsion containing azelaic acid as the
active ingredient and DMSO as a penetration enhancer.
The parties agreed that Gasco did not disclose isopropyl
myristate, lecithin, or triglyceride. The district court
determined that the hypothetical claim was not anticipat-
ed or rendered obvious by Gasco, and rejected Glenmark’s
argument that finding infringement under the doctrine of
equivalents would ensnare Gasco. It reasoned, based on
expert testimony, that a skilled artisan (i) would not
necessarily have substituted the hypothetical claim
excipient (isopropyl myristate or lecithin and triglyceride)
for Gasco’s DMSO, and (ii) would not have had a reasona-
ble expectation of success in doing so.
    Glenmark argues that the district court erred in de-
termining that the doctrine of equivalents was not pre-
cluded by ensnarement. It argues that the district court’s
hypothetical claim was “inexplicably narrower” than
Appellees’ range of equivalents. It argues that a proper
hypothetical claim should have matched Appellees’ theory
of infringement and thus included any penetration en-
hancer. It argues that a proper hypothetical claim would
have been anticipated by or obvious over the prior art and
thus the doctrine of equivalents should be precluded.
12        INTENDIS GMBH   v. GLENMARK PHARMACEUTICALS INC.



     We agree with the district court’s determination that
its infringement finding under the doctrine of equivalents
did not impermissibly read on the prior art. Hypothetical
claims extend the actual claim to literally recite the
accused product. The district court adopted a proper
hypothetical claim, one that includes triglycerides and
lecithin or alternatively isopropyl myristate. It correctly
rejected as too broad Glenmark’s proposed hypothetical
claim which would cover all penetration enhancers. The
district court’s infringement finding was that the excipi-
ent in Glenmark’s product (isopropyl myristate) was
equivalent to the claimed excipients (lecithin and triglyc-
erides); it was not a finding that any penetration enhanc-
er would be equivalent to the claimed excipients. See
Graver Tank & Mfg. Co. v. Linde Air Prods. Co., 339 U.S.
605, 609 (1950) (“What constitutes equivalency must be
determined against the context of the patent, the prior art,
and the particular circumstances of the case. . . . In de-
termining equivalents, things equal to the same thing
may not be equal to each other and, by the same token,
things for most purposes different may sometimes be
equivalents.”). The district court properly rejected Glen-
mark’s argument that the hypothetical claim must be
constructed to capture all penetration enhancers. Glen-
mark does not challenge the district court’s determination
that the hypothetical claim as constructed would have
been patentable. Thus, we see no reversible error in the
district court’s conclusion that Gasco does not bar the
application of the doctrine of equivalents to find Glen-
mark’s generic version to infringe the asserted claims.
             III. Prosecution History Estoppel
    We have summarized the doctrine of prosecution his-
tory estoppel as follows:
     [P]rosecution history estoppel limits the broad ap-
     plication of the doctrine of equivalents by barring
     an equivalents argument for subject matter relin-
INTENDIS GMBH   v. GLENMARK PHARMACEUTICALS INC.         13



   quished when a patent claim is narrowed during
   prosecution. We have recognized that prosecution
   history estoppel can occur during prosecution in
   one of two ways, either (1) by making a narrowing
   amendment to the claim (“amendment-based es-
   toppel”) or (2) by surrendering claim scope
   through argument to the patent examiner (“ar-
   gument-based estoppel”).
Conoco, Inc. v. Energy & Envtl. Int’l, L.C., 460 F.3d 1349,
1363 (Fed. Cir. 2006) (citations omitted). With respect to
the amendment-based estoppel, the Supreme Court has
explained:
   A patentee’s decision to narrow his claims through
   amendment may be presumed to be a general dis-
   claimer of the territory between the original claim
   and the amended claim. There are some cases,
   however, where the amendment cannot reasona-
   bly be viewed as surrendering a particular equiva-
   lent.      The equivalent may have been
   unforeseeable at the time of the application; the
   rationale underlying the amendment may bear no
   more than a tangential relation to the equivalent
   in question; or there may be some other reason
   suggesting that the patentee could not reasonably
   be expected to have described the insubstantial
   substitute in question. In those cases the patent-
   ee can overcome the presumption that prosecution
   history estoppel bars a finding of equivalence.
Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co.,
Ltd., 535 U.S. 722, 740–41 (2002). We review de novo
issues relating to the application of prosecution history
estoppel. Schwarz Pharma, Inc. v. Paddock Labs., Inc.,
504 F.3d 1371, 1375 (Fed. Cir. 2007).
   The district court rejected Glenmark’s argument that
the ’070 patent applicants surrendered a lecithin-free
composition (e.g., Glenmark’s proposed generic product)
14       INTENDIS GMBH   v. GLENMARK PHARMACEUTICALS INC.



as an equivalent during prosecution. During prosecution,
the examiner noted that two dependent claims, which
recited a lecithin “concentration of up to 1%” and “concen-
tration of up to 3%,” respectively, could include zero
lecithin. Applicants responded that those range limita-
tions clearly did not include zero because they “are only in
claims dependent on independent claims, which clearly
require [lecithin].” J.A. 4386–87 (noting that the examin-
er’s argument “is not well taken.”). Regardless, appli-
cants amended the two dependent claims to recite a
lecithin “concentration of from more than 0 to 1%” and
“concentration of from more than 0 to 3%,” respectively,
noting that they were “amended to expressly state what
has already been made clear on the record.” The district
court determined that “taken in context,” the amend-
ments were for clarification purposes, “not to disclaim
formulations with zero lecithin.” It noted that Glenmark
did not dispute that independent claim 1 always required
lecithin, and consequently, both dependent claims also
always required lecithin.
    Glenmark argues that the district court erred in de-
termining that prosecution history estoppel did not apply
to bar the doctrine of equivalents. It argues that appli-
cants expressly disavowed and disclaimed formulations
without lecithin.
     We see no error in the district court’s analysis. The
district court correctly determined that prosecution histo-
ry estoppel did not preclude the capture of Glenmark’s
lecithin-free composition as an equivalent. Argument-
based estoppel only applies when the prosecution history
“evince[s] a clear and unmistakable surrender of subject
matter.” Deering Precision Instruments, LLC v. Vector
Distrib. Sys., Inc., 347 F.3d 1314, 1326 (Fed. Cir. 2003)
(citation and punctuation omitted). Applicants’ clarifying
statement, “Since the dependent claims must limit the
independent claims, the meaning is clear that zero
amounts are not included,” J.A. 4387, did not clearly and
INTENDIS GMBH   v. GLENMARK PHARMACEUTICALS INC.          15



unmistakably disavow claim scope to distinguish prior
art. Amendment-based estoppel does not apply because
the amendment was not a narrowing amendment made to
obtain the patent. Rather, this record demonstrates that
the amendment to the dependent claims was a clarifying
amendment. As dependent claims can never be broader
than the independent claim from which they depend, the
dependent claims as originally written could not have
included 0% lecithin. The amendment was, as the com-
ments themselves make clear, a clarifying amendment
and it does not give rise to prosecution history estoppel.
We see no error in the district court’s determination that
prosecution history estoppel does not apply.
                      IV. Obviousness
     The district court determined that the asserted claims
would not have been obvious over the previously-
marketed Skinoren® cream in combination with
(i) references disclosing formulations containing the
claimed excipients (“non-azelaic acid art”), and
(ii) references disclosing formulations containing azelaic
acid (“azelaic acid art”). 4 Skinoren® cream contained 20%
azelaic acid and was marketed for skin conditions. The
district court found that Skinoren®’s formulation had
certain undesirable qualities, and that a skilled artisan
would consider developing an alternative to Skinoren® in
a different dosage form given the market forces and the
deficiencies of Skinoren®. It also found that a skilled
artisan would have been motivated to pursue a hydrogel
formulation of azelaic acid based on Maru, one of the
pieces of azelaic acid art, which the district court found to


    4   The non-azelaic acid art was PCT Application
Pub. Nos. WO 93/18752 and WO 95/05163. The azelaic
acid art was articles by Maru, Gasco, and Pattarino; U.S.
Patent No. 5,385,943; and PCT Application Pub.
No. WO 93/39119.
16       INTENDIS GMBH   v. GLENMARK PHARMACEUTICALS INC.



disclose a hydrogel formulation containing azelaic acid. It
found, however, that the record did not show that the
artisan would have been motivated to use the claimed
excipients (triglyceride and lecithin). It noted that Glen-
mark’s only support to combine Maru with either of the
two references that disclose the claimed excipients was
the testimony by Glenmark’s expert that a skilled artisan
“could have put . . . information together from another two
publications” to render claim 1 obvious. It reasoned that
this cursory statement was insufficient to meet Glen-
mark’s burden of showing by clear and convincing evi-
dence a motivation to combine Maru with other prior art
to render the claims obvious. It also found that even if
Glenmark had presented evidence to show motivation to
combine, Glenmark failed to carry its burden to demon-
strate a reasonable expectation of success in making the
combination. It found—based on fact and expert testimo-
ny—that “swapping ingredients in complex chemical
formulations is anything but ‘routine.’” J.A. 65. It wrote
that Glenmark did not present testimony or other evi-
dence regarding an expectation of success. It also deter-
mined that the objective indicia of unexpected results and
commercial success supported its conclusion of nonobvi-
ousness.
    Glenmark argues that the district court erred in con-
cluding that the asserted claims would not have been
obvious. It argues that a skilled artisan would have
known how to “successfully” combine the non-azelaic acid
art with the azelaic acid art. It argues that the objective
indicia do not overcome its “strong” prima facie case of
obviousness. According to Glenmark, the district court
erred in finding that the claimed compositions demon-
strated unexpected results. It also argues Appellees’
“equivocal” evidence concerning commercial success does
not support the district court’s nonobviousness conclusion.
    The district court correctly concluded that the assert-
ed claims would not have been obvious. We discern no
INTENDIS GMBH   v. GLENMARK PHARMACEUTICALS INC.         17



clear error in the district court’s finding that a skilled
artisan would not have been motivated to combine the
prior art or in finding no reasonable expectation of success
based on the evidence of record. Moreover, we see no
clear error in the district court’s findings with respect to
objective indicia of nonobviousness.
                       CONCLUSION
    The district court did a commendable job in rendering
its detailed and thorough opinion. Because we see no
reversible error in the district court’s decision that Glen-
mark’s generic product infringed the asserted claims and
that the asserted claims are not invalid, the district
court’s judgment is affirmed.
                       AFFIRMED
                          COSTS
   Costs to the Appellees.
