Case: 22-2217    Document: 61     Page: 1   Filed: 07/24/2023




   United States Court of Appeals
       for the Federal Circuit
                  ______________________

     UNITED THERAPEUTICS CORPORATION,
             Plaintiff-Cross-Appellant

                             v.

          LIQUIDIA TECHNOLOGIES, INC.,
                Defendant-Appellant
               ______________________

                   2022-2217, 2023-1021
                  ______________________

     Appeals from the United States District Court for the
 District of Delaware in No. 1:20-cv-00755-RGA-JLH, Judge
 Richard G. Andrews.
                  ______________________

                  Decided: July 24, 2023
                  ______________________

    SANYA SUKDUANG, Cooley LLP, Washington, DC, ar-
 gued for defendant-appellant.  Also represented by
 JONATHAN DAVIES; DEEPA KANNAPPAN, Palo Alto, CA; ERIK
 BENTON MILCH, Reston, VA.

    WILLIAM M. JAY, Goodwin Procter LLP, Washington,
 DC, argued for plaintiff-cross-appellant. Also represented
 by WILLIAM COVINGTON JACKSON, JAIME SANTOS,
 ROHINIYURIE TASHIMA, JENNY J. ZHANG; GERARD JUSTIN
 CEDRONE, Boston, MA; ADAM WILLIAM BURROWBRIDGE.
 McDermott Will & Emery, LLP, Washington, DC;
 DOUGLAS H. CARSTEN, ARTHUR PAUL DYKHUIS, Irvine, CA;
Case: 22-2217    Document: 61      Page: 2    Filed: 07/24/2023




 2                      UNITED THERAPEUTICS CORPORATION v.
                                LIQUIDIA TECHNOLOGIES, INC.


 SHAUN R. SNADER, United Therapeutics Corporation,
 Washington, DC.
                 ______________________

      Before LOURIE, DYK, and STOLL, Circuit Judges.
 LOURIE, Circuit Judge.
     Liquidia Technologies, Inc. (“Liquidia”) appeals from a
 decision of the United States District Court for the District
 of Delaware holding that (1) claims 1, 4, and 6–8 of U.S.
 Patent 10,716,793 (“the ’793 patent”) are not invalid and
 are infringed by Liquidia and (2) claims 1–3 of U.S. Patent
 9,593,066 (“the ’066 patent”) are invalid as anticipated, but
 are otherwise infringed by Liquidia. United Therapeutics
 Corporation (“United Therapeutics”) cross-appeals from
 the court’s decision holding that (1) claims 1–3, 6, and 9 of
 the ’066 patent are invalid as anticipated and (2) claims 6,
 8, and 9 of the ’066 patent are not infringed by Liquidia.
 See United Therapeutics Corp. v. Liquidia Techs., Inc., 

 (D. Del. 2022) (“Decision”). For the reasons
 provided below, we affirm.
                        BACKGROUND
     United Therapeutics holds New Drug Application
 (“NDA”) No. 022387 for Tyvaso®, an inhaled solution for-
 mulation of treprostinil approved for the treatment of pul-
 monary hypertension (“PH”). Pulmonary hypertension is a
 potentially life-threatening condition characterized gener-
 ally by abnormally high blood pressure in the lungs. For
 many patients, treprostinil is used in treating pulmonary
 hypertension because it is a vasodilator that reduces vaso-
 constriction in the pulmonary vasculature, thereby de-
 creasing blood pressure.
       Experts consider that there are five subgroups of pul-
 monary hypertension: Group 1, pulmonary arterial hyper-
 tension (“PAH”); Group 2, pulmonary venous hypertension,
 i.e., pulmonary hypertension related to left-heart disease;
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 UNITED THERAPEUTICS CORPORATION    v.                     3
 LIQUIDIA TECHNOLOGIES, INC.


 Group 3, pulmonary hypertension associated with disor-
 ders damaging the lungs; Group 4, pulmonary hyperten-
 sion caused by chronic thrombotic or embolic disease,
 including chronic blood clots in the lungs; and Group 5, a
 miscellaneous category for conditions that do not fit well
 into the other four subgroups. Groups 1, 3, 4, and 5 are
 caused by conditions affecting the pulmonary arteries or
 precapillary vessels of the lungs (“precapillary PH”), while
 Group 2 typically develops as a result of a cardiac-based
 etiology (“postcapillary PH”). Due to differing etiologies,
 each group may require group-specific treatment.
      United Therapeutics owns the ’793 and ’066 patents,
 which are generally directed to methods of treating pulmo-
 nary hypertension and to pharmaceutical compositions
 comprising treprostinil. The ’793 and ’066 patents are
 listed in the FDA’s Orange Book for Tyvaso.
     Liquidia filed NDA No. 213005 for Yutrepia™ under
 § 505(b)(2) of the Food, Drug, and Cosmetic Act (codified at
 

(b)(2)). 1 Yutrepia is a dry powder


    1     Under the Drug Price Competition and Patent
 Term Restoration Act of 1984 (the Hatch-Waxman amend-
 ments to the Food, Drug, and Cosmetic Act), an NDA filed
 under § 505(b)(2) contains full reports of investigations of
 safety and effectiveness, where at least some of the infor-
 mation used for approval comes from studies that were not
 conducted for or by the applicant. Such an NDA is one of
 two abbreviated approval pathways introduced by the
 Hatch-Waxman amendments, the other being an abbrevi-
 ated new drug application (“ANDA”) filed under § 505(j)
 (codified at 

(j)). 

(e)(2), the
 statutory provision delineating acts of infringement, covers
 both types of applications: “It shall be an act of infringe-
 ment to submit . . . an application under section 505(j) of
 the Federal Food, Drug, and Cosmetic Act or described in
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 4                       UNITED THERAPEUTICS CORPORATION v.
                                 LIQUIDIA TECHNOLOGIES, INC.


 inhalation formulation of treprostinil but is not a generic
 version of any currently marketed drug. Pursuant to §
 505(c)(3)(C) (codified at 

(c)(3)(C)), United
 Therapeutics sued Liquidia within 45 days of receipt of no-
 tice of Liquidia’s NDA in the United States District Court
 for the District of Delaware alleging infringement of the
 ’066 patent. J.A. 171, 190. In addition, after Liquidia filed
 its NDA, United Therapeutics filed another patent applica-
 tion that eventually issued as the ’793 patent, which was
 subsequently added to the district court litigation. J.A.
 208.
      In parallel, Liquidia filed a petition for inter partes re-
 view (“IPR”) of the ’793 patent, alleging that all claims
 would have been unpatentable as obvious over prior art at
 the time of the invention. On July 19, 2022, the Board is-
 sued a Final Written Decision finding all claims of the ’793
 patent unpatentable as obvious. Liquidia Techs., Inc. v.
 United Therapeutics Corp., No. IPR2021-00406, 

 (P.T.A.B. July 19, 2022). United Therapeutics
 filed a Request for Rehearing, challenging whether various
 asserted references qualified as prior art. J.A. 36648. In
 its Rehearing Decision, the Board found that the references
 were prior art, again holding the claims of the ’793 patent
 unpatentable as obvious. United Therapeutics filed a No-
 tice of Appeal in that case on April 26, 2023. Liquidia filed
 a motion for expedited appeal, which has been denied. The
 appeal is currently pending in this court.
                       I. The ’793 Patent
     The ’793 patent is directed to a method of treating pul-
 monary hypertension comprising inhalation of treprostinil.
 Asserted claim 1 of the ’793 patent is the only independent
 claim and reads as follows:



 section 505(b)(2) of such Act for a drug claimed in a patent
 or the use of which is claimed in a patent[.]”
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 UNITED THERAPEUTICS CORPORATION      v.                     5
 LIQUIDIA TECHNOLOGIES, INC.


        1.    A method of treating pulmonary hyper-
        tension comprising administering by inhala-
        tion to a human suffering from pulmonary
        hypertension a therapeutically effective sin-
        gle event dose of a formulation comprising
        treprostinil or a pharmaceutically acceptable
        salt thereof with an inhalation device,
        wherein the therapeutically effective single
        event dose comprises from 15 micrograms to
        90 micrograms of treprostinil or a pharmaceu-
        tically acceptable salt thereof delivered in 1 to
        3 breaths.
 ’793 patent at col. 18 ll. 23–31.
     The additional asserted dependent claims include lim-
 itations directed to dry powder inhalers (claim 4), powder
 formulations (claim 6), powder formulations comprising
 particles less than 5 micrometers in diameter (claim 7), and
 formulations containing no metacresol (claim 8). See 

 col.
 18 ll. 36–37, 40–45.
     In the district court, United Therapeutics argued that,
 although Liquidia’s proposed product had not yet been
 marketed, when marketed, it (1) would directly infringe
 claims 1, 4, and 6–8 of the ’793 patent and (2) would also
 induce infringement of those claims. Liquidia responded
 that the asserted claims were invalid as lacking adequate
 enablement and written description under 

.
     The district court found that United Therapeutics
 showed that a single administration of treprostinil, as re-
 quired by claim 1, improves a patient’s hemodynamics, es-
 tablishing that administration of Liquidia’s Yutrepia,
 comprising treprostinil, at the claimed doses will also im-
 prove a patient’s hemodynamics. The court concluded that
 United Therapeutics thus proved by a preponderance of the
 evidence that the administration of Yutrepia will directly
 infringe claims 1, 4, and 6–8 of the ’793 patent.
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 6                       UNITED THERAPEUTICS CORPORATION v.
                                 LIQUIDIA TECHNOLOGIES, INC.


     The district court also concluded that Liquidia’s argu-
 ment that it lacked specific intent to induce infringement
 lacked merit. Liquidia argued that, because the Yutrepia
 label does not encourage administration of a therapeuti-
 cally effective single event dose, it does not induce infringe-
 ment. The court noted that the label does not need to
 provide hemodynamic data to constitute inducement of in-
 fringement; instead, it merely needs to instruct doctors and
 patients to administer a therapeutically effective single
 event dose. The court found that the label’s instructions
 will inevitably lead to the administration of a therapeuti-
 cally effective single event dose. The court thus concluded
 that United Therapeutics proved by a preponderance of the
 evidence that Liquidia will induce infringement of claims
 1, 4, and 6–8 of the ’793 patent.
      The district court further found that the asserted
 claims were not invalid for lack of enablement or written
 description. First, the court construed “treating pulmo-
 nary hypertension” as encompassing all five groups of pul-
 monary hypertension, noting that the specification of
 the ’793 patent expressly includes all five groups when de-
 scribing “pulmonary hypertension.” Second, the court
 found that a skilled artisan would not need to engage in
 undue experimentation to practice the full scope of the
 claimed treatment of pulmonary hypertension, despite po-
 tential safety concerns in treating Group 2 PH patients,
 and that the claims did not require safety and efficacy.
 Third, the court found that the claims were not invalid for
 lack of written description, finding that a skilled artisan
 would, based on the specification, understand that trepros-
 tinil would effectively vasodilate the pulmonary vascula-
 ture, improve hemodynamics, and treat a patient’s
 elevated pulmonary blood pressure. As a result of the
 court’s findings that the claims were not invalid but were
 infringed, the court stayed approval of Liquidia’s NDA for
 Yutrepia until May 5, 2027, the expiration date of the ’793
 patent.
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 UNITED THERAPEUTICS CORPORATION        v.                     7
 LIQUIDIA TECHNOLOGIES, INC.


                          II. The ’066 Patent
      The ’066 patent is directed to a pharmaceutical compo-
 sition comprising treprostinil and a process of preparing a
 pharmaceutical product comprising treprostinil.
     Asserted claim 1 of the ’066 patent reads as follows:
        1.    A pharmaceutical composition compris-
        ing treprostinil or a pharmaceutically ac-
        ceptable salt thereof, said composition
        prepared by a process comprising providing a
        starting batch of treprostinil having one or
        more impurities resulting from prior alkyla-
        tion and hydrolysis steps, forming a salt of
        treprostinil by combining the starting batch
        and a base, isolating the treprostinil salt, and
        preparing a pharmaceutical composition com-
        prising treprostinil or a pharmaceutically ac-
        ceptable salt thereof from the isolated
        treprostinil salt, whereby a level of one or
        more impurities found in the starting batch of
        the treprostinil is lower in the pharmaceutical
        composition, and wherein said alkylation is
        alkylation of benzindene triol.
 ’066 patent at col. 17 ll. 51–63.
     Asserted claim 6 of the ’066 patent reads:
        6.   The pharmaceutical composition of
        claim 1, wherein the isolated salt is stored at
        ambient temperature.
 

 col. 18 ll. 34–35.
     Asserted claim 8 of the ’066 patent reads:
        8.   A process of preparing a pharmaceutical
        product comprising treprostinil or a pharma-
        ceutically acceptable salt thereof, comprising
        alkylating a triol intermediate of the formula:
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 8                        UNITED THERAPEUTICS CORPORATION v.
                                  LIQUIDIA TECHNOLOGIES, INC.




         hydrolyzing the resulting compound to form
         treprostinil, forming a salt of treprostinil sta-
         ble at ambient temperature, storing the
         treprostinil salt at ambient temperature, and
         preparing a pharmaceutical product from the
         treprostinil salt after storage, wherein the
         pharmaceutical product comprises treprosti-
         nil or a pharmaceutically acceptable salt
         thereof.
 

 col. 18 ll. 38–61.
     Additional asserted dependent claims are directed to
 crystalline forms (claim 2), a base selected from the group
 consisting of sodium, ammonia, potassium, calcium, etha-
 nolamine, diethanolamine, N-methylglucamine, and cho-
 line (claim 3), and a pharmaceutical product prepared by
 the process recited in claim 8 (claim 9). See 

 col. 17 ll.
 64–67; col. 18 ll. 27–28, 62–63.
     In the district court, United Therapeutics argued that
 Liquidia infringed claims 1–3, 6, 8, and 9 of the ’066 patent.
 Liquidia responded that claims 1–3, 6, and 9 were invalid
 as anticipated by Moriarty 2 and that claims 1–3 and 6 were
 invalid as lacking written description support. Liquidia did
 not challenge the validity of claim 8, which is a chemical




     2   R.M. Moriarty et al., The Intramolecular Asymmet-
 ric Pauson-Khand Cyclization as a Novel and General Ste-
 reoselective Route to Benzindene Prostacyclins: Synthesis of
 UT-15 (Treprostinil), 69 J. ORGANIC CHEM. 1890 (2004).
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 UNITED THERAPEUTICS CORPORATION    v.                      9
 LIQUIDIA TECHNOLOGIES, INC.


 process claim, in contrast to the other claims that are di-
 rected to compositions.
     The district court found that United Therapeutics
 showed by a preponderance of the evidence that Liquidia’s
 Yutrepia would infringe claims 1–3 of the ’066 patent be-
 cause Yutrepia met the impurities limitations of claim 1.
 But the court also found that claims 1–3, 6, and 9 were in-
 valid as anticipated by Moriarty. Moriarty discloses the
 synthesis of analogues of benzindene prostacyclins, includ-
 ing treprostinil, which is designated in the publication as
 UT-15. Moriarty at 1890, 1892. The court also found that
 Liquidia showed by clear and convincing evidence that the
 claimed treprostinil product is functionally and structur-
 ally the same as the UT-15 treprostinil disclosed in Mori-
 arty. The court thus concluded that claims 1–3 would have
 been infringed by Liquidia, but for the finding of anticipa-
 tion, and that claims 6 and 9 were invalid as anticipated by
 Moriarty but not infringed by Liquidia.
      In finding a lack of infringement of claim 6, the court
 construed the terms “ambient temperature” as room tem-
 perature (equal to or less than the range of 15°C to 30°C)
 and “stored”/“storing”/“storage” to have its plain and ordi-
 nary meaning. Using these constructions, the court deter-
 mined that United Therapeutics failed to show by a
 preponderance of the evidence that Liquidia’s Yutrepia
 production process stored treprostinil at ambient tempera-
 ture, and therefore found that claims 6, 8, and 9 were not
 infringed. The court further found that any storage be-
 tween steps of Liquidia’s manufacturing process did not
 meet the limitations of claims 8 and 9, which require stor-
 age of treprostinil before preparing a pharmaceutical prod-
 uct.
     The district court also found that the specification pro-
 vided adequate written description support for the impuri-
 ties limitation in claim 1, and that a skilled artisan would
 understand that the inventors were in possession of the
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 10                     UNITED THERAPEUTICS CORPORATION v.
                                LIQUIDIA TECHNOLOGIES, INC.


 composition with the claimed impurities. The court thus
 concluded that Liquidia did not prove by clear and convinc-
 ing evidence that claims 1–3 and 6 of the ’066 patent were
 invalid for lack of written description.
     In summary, the district court concluded that (1)
 claims 1, 4, and 6–8 of the ’793 patent were not invalid and
 were infringed by Liquidia; (2) claims 1–3 of the ’066 patent
 were invalid as anticipated by Moriarty and would have
 been infringed by Liquidia but for the finding of anticipa-
 tion; (3) claims 6 and 9 of the ’066 patent were invalid as
 anticipated by Moriarty and not infringed by Liquidia; and
 (4) claim 8 of the ’066 patent was not invalid and not in-
 fringed by Liquidia. Liquidia appealed, and United Ther-
 apeutics cross-appealed. We have jurisdiction under 

(a)(1).
                         DISCUSSION
      Liquidia raises five issues on appeal. First, Liquidia
 contends that the district court erred in construing the
 claim limitation “treating pulmonary hypertension” in
 claim 1 of the ’793 patent not to include safety and efficacy.
 Second, Liquidia argues that the court erred in finding the
 asserted claims of the ’793 patent enabled. Third, Liquidia
 contends that the court clearly erred in finding the asserted
 claims of the ’793 patent supported by written description.
 Fourth, Liquidia contends that the court clearly erred in
 finding Liquidia liable for induced infringement of claims
 1, 4, and 6–8 of the ’793 patent. Fifth, Liquidia argues that
 the court clearly erred in finding claims 1–3 of the ’066 pa-
 tent to be infringed.
     United Therapeutics raises two issues on cross-appeal.
 First, United Therapeutics asserts that the district court
 clearly erred in finding that Liquidia does not infringe
 claims 6 and 8 of the ’066 patent. Second, United Thera-
 peutics contends that the court clearly erred in finding that
 claims 1–3, 6, and 9 of the ’066 patent are invalid as
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 UNITED THERAPEUTICS CORPORATION     v.                     11
 LIQUIDIA TECHNOLOGIES, INC.


 anticipated by Moriarty. We address each appeal and
 cross-appeal argument in turn.
     Infringement is a question of fact that we review, after
 a bench trial, for clear error. Eli Lilly & Co. v. Teva Paren-
 teral Meds., Inc., 

 (Fed. Cir. 2017). A
 patent is directly infringed when a person “without author-
 ity makes, uses, offers to sell, or sells any patented inven-
 tion, within the United States or imports into the United
 States any patented invention during the term of the pa-
 tent.” 

(a). “Whoever actively induces in-
 fringement of a patent shall be liable as an infringer.” 

 § 271(b).
     We review district court findings of anticipation under
 

 and satisfaction of the written description
 requirement under 

 for clear error. Nuvo
 Pharms. (Ir.) Designated Activity Co. v. Dr. Reddy’s Lab’ys
 Inc., 

 (Fed. Cir. 2019) (written descrip-
 tion); Forest Lab’ys, Inc. v. Ivax Pharms., Inc., 

 (Fed. Cir. 2007) (anticipation). Enablement “is
 a question of law” that we review de novo after a bench trial.
 Auto. Techs. Int’l, Inc. v. BMW of N. Am., Inc., 

 (Fed. Cir. 2007). We review questions of claim
 construction de novo but review any underlying facts for
 clear error. Markman v. Westview Instruments, Inc., 

 (Fed. Cir. 1995); Eli Lilly & Co. v. Hos-
 pira, Inc., 

 (Fed. Cir. 2019).
                      I. The ’793 Patent
                              A.
     We first consider Liquidia’s challenge to the district
 court’s determination that the meaning of “treating pulmo-
 nary hypertension” does not require a showing of safety
 and efficacy. It asserts that a skilled artisan would under-
 stand the plain and ordinary meaning of “treating pulmo-
 nary hypertension” to encompass a method that
 accomplishes that goal safely and effectively. It asserts
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 12                      UNITED THERAPEUTICS CORPORATION v.
                                 LIQUIDIA TECHNOLOGIES, INC.


 that the parties’ experts agreed that treatment with
 treprostinil, a vascular dilator, would not benefit Group 2
 PH patients. It further asserts that while the specification
 of the ’793 patent states that the treatment does not result
 in significant side effects, ’793 patent at col. 5 ll. 16–20, and
 that administration of treprostinil is safe, 

 col. 9 ll. 30–
 31, its expert testified that a skilled artisan would have
 concerns about administering inhaled treprostinil to Group
 2 PH patients and that at least one earlier study, in which
 a treprostinil-like prostacyclin was administered to Group
 2 PH patients, failed due to increased mortality.
     United Therapeutics responds that the district court
 did not err in finding that the claimed administration of
 treprostinil would improve hemodynamics and hence treat
 a patient’s elevated pulmonary blood pressure, including
 Group 2 PH patients. It asserts that Liquidia attempts to
 import limitations into the claims and that nothing in the
 specification requires the importation of safety and efficacy
 limitations into the claims. Finally, United Therapeutics
 asserts that while Liquidia’s statements that a skilled ar-
 tisan would have safety concerns in treating Group 2 PH
 patients with treprostinil may factor into Food and Drug
 Administration (“FDA”) approval, they do not factor into
 claim interpretation.
      As a threshold matter, we agree with the district court
 that “treating pulmonary hypertension” includes treating
 all five groups of pulmonary hypertension patients. The
 court did not err in finding that the specification encom-
 passes all five groups when describing “pulmonary hyper-
 tension.” In fact, the specification does not limit the scope
 of “pulmonary hypertension” to any particular subset of
 pulmonary hypertension patients. It refers to both “preca-
 pillary pulmonary hypertension” and “pulmonary hyper-
 tension,” which, as the court found, demonstrates that the
 inventors view precapillary PH only as a subset of the
 broadly claimed “pulmonary hypertension.” Thus, “treat-
 ing pulmonary hypertension” includes treating all five
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 UNITED THERAPEUTICS CORPORATION    v.                     13
 LIQUIDIA TECHNOLOGIES, INC.


 groups of pulmonary hypertension. See ’793 patent at col.
 9 ll. 36–37, col. 12 ll. 64–65, col. 16 ll. 64–65.
     While the claims require “treating pulmonary hyper-
 tension comprising administering . . . a therapeutically ef-
 fective single event dose of a formulation comprising
 treprostinil,” Decision, at 467, the district court gave the
 phrase “therapeutically effective” a limiting construction.
 The district court held, and Liquidia does not challenge on
 appeal, that a person of ordinary skill in the art “would un-
 derstand the plain and ordinary meaning of ‘therapeuti-
 cally effective single dose’ to be a dose given in a single
 treatment session that causes an improvement in a pa-
 tient’s hemodynamics (reduced PAP or PVR).” Id. at 461;
 Appellee’s Br. 39. We need not address whether the district
 court’s construction was correct because Liquidia, on ap-
 peal, does not challenge that construction. Read in context,
 the claim language “treating pulmonary hypertension”
 does not import any additional efficacy limitations or any
 safety limitations.
     Absent incorporation of safety and efficacy require-
 ments in the claims, Liquidia’s argument concerning the
 safety and efficacy of treating Group 2 PH patients is not
 before us. Questions of safety and efficacy in patent law
 have long fallen under the purview of the FDA. In re Brana,
 

 (Fed. Cir. 1995) (noting that “the re-
 quirements under the law for obtaining a patent” are dif-
 ferent from “the requirements for obtaining government
 approval to market a particular drug for human consump-
 tion”); Scott v. Finney, 

 (Fed. Cir. 1994)
 (“Testing for the full safety and effectiveness . . . is more
 properly left to the [FDA]. Title 35 does not demand that
 such human testing occur within the confines of Patent and
 Trademark Office (PTO) proceedings.”); In re Anthony, 

 (CCPA 1969) (“Congress has given the re-
 sponsibility to the FDA, not to the Patent Office, to deter-
 mine in the first instance whether drugs are sufficiently
 safe for use that they can be introduced in the commercial
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 14                     UNITED THERAPEUTICS CORPORATION v.
                                LIQUIDIA TECHNOLOGIES, INC.


 market . . . .”). We decline to insert the FDA’s responsibil-
 ities into claims by importing requirements where they do
 not recite such limitations.
                              B.
     We next turn to Liquidia’s challenge to the district
 court’s finding that the claims of the ’793 patent are ade-
 quately enabled and supported by written description.
 Liquidia argues that the specification of the ’793 patent
 provides no guidance or examples of treating Group 2 PH
 patients, and thus that a skilled artisan would have to en-
 gage in undue experimentation to practice the full scope of
 the claimed invention (i.e., treating Group 2 PH patients).
     Liquidia further argues that, even if the district court’s
 construction of “treating pulmonary hypertension” as not
 requiring safety was proper, the claims of the ’793 patent
 would still not be enabled because any changes in hemody-
 namics caused by inhalation of treprostinil would provide
 no benefit to Group 2 PH patients. Thus, a skilled artisan
 would not conclude that the ’793 patent claims are enabled
 to the full scope of the claimed invention.
     United Therapeutics responds that the district court
 did not err in concluding that Liquidia failed to show a lack
 of enablement. It contends that Liquidia failed to show by
 clear and convincing evidence that enablement would re-
 quire undue experimentation with respect to Group 2 PH.
      Further, even if the specification fails to describe how
 to treat Group 2 PH patients with treprostinil, United
 Therapeutics asserts, claims are not required to carve out
 all possible inoperative embodiments in a claim in order to
 avoid that claim being found not to be enabled. United
 Therapeutics asserts that if a skilled artisan has the infor-
 mation to limit the claims to operative embodiments, then
 the claims are not invalid. Here, United Therapeutics as-
 serts, the skilled artisan has that information.
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 UNITED THERAPEUTICS CORPORATION      v.                     15
 LIQUIDIA TECHNOLOGIES, INC.


     Liquidia also challenges the district court’s finding that
 the claims are supported by an adequate written descrip-
 tion. Liquidia argues that the ’793 patent never describes
 treating Group 2 PH patients with inhaled treprostinil, but
 only Group 1, 3, and 4 patients, all of whom have precapil-
 lary PH. Thus, Liquidia contends, there is no information
 in the ’793 patent specification sufficient for a skilled arti-
 san to conclude that the inventors were in possession of a
 method of treating Group 2 PH patients with inhaled
 treprostinil.
     Liquidia further argues that, even if the district court
 correctly construed “treating pulmonary hypertension” not
 to require a showing of safety, the claims still are not sup-
 ported by written description because vasodilation of the
 pulmonary vasculature is not effective in treating Group 2
 PH patients. Thus, Liquidia contends, a skilled artisan
 would have understood that the inventors did not invent or
 possess a method of treating Group 2 PH patients.
     United Therapeutics responds that the district court
 did not clearly err in finding the claims of the ’793 patent
 supported by an adequate written description. United
 Therapeutics argues that Liquidia’s written description ar-
 guments fail for largely the same reasons as its enablement
 arguments. In particular, United Therapeutics asserts
 that the court did not err in holding that a skilled artisan
 would understand a therapeutically effective dose to be one
 that improves a patient’s hemodynamics. United Thera-
 peutics further contends that, although a physician may or
 may not decide to administer treprostinil to a Group 2 PH
 patient, that decision would be informed by FDA guidance,
 not the written description in the specification.
     We agree with United Therapeutics that the claims are
 adequately enabled as they were construed by the district
 court. The specification of the ’793 patent sufficiently ena-
 bles the scope of the claims. See, e.g., ’793 patent at col. 7
 ll.   7–67    (providing    details    on    administration,
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 16                     UNITED THERAPEUTICS CORPORATION v.
                                LIQUIDIA TECHNOLOGIES, INC.


 concentrations, and dosages of inhaled treprostinil for
 treating patients with pulmonary hypertension); 

 col. 9
 ll. 5–49 (describing an open label study upon acute safety,
 tolerability, and hemodynamic effects of inhaled treprosti-
 nil delivered over the course of a few seconds). While the
 court credited expert testimony concluding that a physi-
 cian may have safety concerns in treating Group 2 PH pa-
 tients with treprostinil and other vasodilators, see Decision,
 at 466–67, the court also found that the record demon-
 strates that the claimed administration of treprostinil vas-
 odilates the pulmonary vasculature and reduces
 pulmonary blood pressure even in Group 2 PH patients, id.
 at 468. The court properly relied on expert testimony and
 record evidence to conclude that a skilled artisan would un-
 derstand that the claimed administration of treprostinil
 would vasodilate the pulmonary vasculature, improve he-
 modynamics, and in this way for a single dose, treat a pa-
 tient’s elevated pulmonary blood pressure independent of
 the type (i.e., group) of pulmonary hypertension patient. Id.
 That was all that the claims require under the district
 court’s construction because, again, the parties do not dis-
 pute that a “therapeutically effective single event dose” is
 defined by “an improvement in a patient’s hemodynamics
 (reduced PAP or PVP).” That a study—administering
 treprostinil-like prostacyclins to Group 2 PH patients—
 failed due to increased mortality, yet showed “improve-
 ment in a patient’s hemodynamics,” may be an issue for the
 FDA. But our focus is on the claimed invention. And on
 this record, with the district court’s claim construction, the
 claims are adequately enabled.
      We also agree with United Therapeutics that the dis-
 trict court did not clearly err in finding that the claims of
 the ’793 patent are supported by an adequate written de-
 scription. Written description requires that the specifica-
 tion reasonably convey to those skilled in the art that the
 inventor had possession of the claimed invention as of the
 filing date. Ariad Pharms., Inc. v. Eli Lilly & Co., 598 F.3d
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 UNITED THERAPEUTICS CORPORATION     v.                     17
 LIQUIDIA TECHNOLOGIES, INC.


 1336, 1351 (Fed. Cir. 2010) (en banc). As the court noted,
 the ’793 patent claims require “treating pulmonary hyper-
 tension comprising administering . . . a therapeutically ef-
 fective single event dose of a formulation containing
 treprostinil,” Decision, at 466–67, and the specification de-
 scribes that. In other words, the specification shows pos-
 session for the claimed invention under the district court’s
 construction.
     Liquidia essentially asks us to treat Group 2 PH as a
 claimed species within a larger genus (i.e., all five groups
 of pulmonary hypertension). But analogizing a subset of
 patients having a variant of a particular disease to tradi-
 tional genus and species claims is inapt. It would be incor-
 rect to fractionate a disease or condition that a method of
 treatment claim is directed to, and to require a separate
 disclosure in the specification for each individual variant of
 the condition (here, an individual group of pulmonary hy-
 pertension patients) in order to satisfy the enablement and
 written description provisions of 

, unless
 these variants are specified in the claims.
      Again, because safety and efficacy are not recited in the
 claims, we need not deal with Liquidia’s arguments. Dis-
 ease-specific treatment requirements are matters for the
 FDA and medical practitioners. They are best suited to
 make these determinations because practitioners are in-
 formed by the findings of the regulatory agency to avoid
 treatment of patients who will not properly respond. And
 every claim to a method of treatment of an ailment has re-
 finements. That is, for any given method of treatment
 claim, there may be a subset of patients who would not ben-
 efit from or should not take the claimed treatment. See
 Oral      Arg.      at      4:28–4:58,      https://oralargu-
 ments.cafc.uscourts.gov/default.aspx?fl=22-2217_0503202
 3.mp3. That does not mean that such claims are not suffi-
 ciently enabled or supported by written description. A sub-
 set of unresponsive patients is not analogous to
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 18                     UNITED THERAPEUTICS CORPORATION v.
                                LIQUIDIA TECHNOLOGIES, INC.


 unsupported species in a generic claim to chemical com-
 pounds.
                              C.
     We next turn to Liquidia’s challenge to the district
 court’s finding that Liquidia was liable for induced in-
 fringement. Liquidia argues that it cannot be held liable
 for induced infringement because the ’793 patent was
 found to be unpatentable in an IPR, and an unpatentable
 or invalid patent cannot be infringed. To support this as-
 sertion, Liquidia cites Commil USA, LLC v. Cisco Systems,
 Inc., 

 (2015) (stating that if “an act that
 would have been . . . an inducement to infringe pertains to
 a patent that is shown to be invalid, there is no patent to
 be infringed”). Liquidia contends that Commil should be
 read as stating that knowledge of actual unpatentability
 determined in an IPR precludes having the necessary in-
 tent to induce infringement.
     United Therapeutics responds that the Board’s deci-
 sion on the ’793 patent is not final, and a non-final Board
 decision does not defeat Liquidia’s liability for inducing in-
 fringement of the ’793 patent. United Therapeutics con-
 tends that unpatentability is relevant to infringement
 liability only once a final adjudication of unpatentability or
 invalidity rules that there is no such patent to infringe.
      We agree with United Therapeutics that the district
 court did not clearly err in finding that Liquidia induced
 infringement of the ’793 patent. The court did not clearly
 err in finding that the label on Yutrepia, Liquidia’s product,
 does not need to provide hemodynamic data to constitute
 inducement of infringement; it merely needs to instruct
 doctors and patients to administer a therapeutically effec-
 tive single event dose, which it does. Decision, at 462–63.
 The court also did not clearly err in concluding that United
 Therapeutics proved that a single administration of Yutre-
 pia will be therapeutically effective, as required by the
 claims of the ’793 patent and constituting inducement.
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 UNITED THERAPEUTICS CORPORATION     v.                     19
 LIQUIDIA TECHNOLOGIES, INC.


     Liquidia’s reliance on Commil, 

, re-
 quires the ’793 patent to have been invalidated, but as
 United Therapeutics argues, the corresponding IPR pro-
 ceeding of the ’793 patent is pending on appeal in this court.
 A pending, non-final litigation does not negate an intent to
 infringe that is otherwise supported by evidence. And we
 have previously held that an IPR decision does not have
 collateral estoppel effect until that decision is affirmed or
 the parties waive their appeal rights. XY, LLC v. Trans
 Ova Genetics, L.C., 

 (Fed. Cir. 2018)
 (“[A]n affirmance of an invalidity finding, whether from a
 district court or the Board, has a collateral estoppel effect
 on all pending or co-pending actions.”). Further, as the
 court noted, the Board’s final written decision does not can-
 cel claims; the claims are cancelled when the Director is-
 sues a certificate confirming unpatentability, which occurs
 only after “the time for appeal has expired or any appeal
 has terminated.” 

(b). The ’793 IPR decision
 thus has no impact here on a finding of induced infringe-
 ment.
                     II. The ’066 Patent
                              A.
     We next turn to Liquidia’s assertion on appeal that the
 district court clearly erred in finding that it infringed
 claims 1–3 of the ’066 patent. Liquidia argues that United
 Therapeutics failed to meet its burden of proving infringe-
 ment. In particular, Liquidia argues that United Thera-
 peutics identified the starting batch as the treprostinil salt
 and the pharmaceutical composition as the bulk powder.
 Liquidia thus contends that a comparison between the im-
 purities in the treprostinil salt and bulk powder would
 have been required to establish infringement of claims that
 require a lowering of impurities.
     United Therapeutics responds that the district court
 did not clearly err in finding that Liquidia infringed claims
 1–3 of the ’066 patent. United Therapeutics contends that
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 20                      UNITED THERAPEUTICS CORPORATION v.
                                 LIQUIDIA TECHNOLOGIES, INC.


 the court based its conclusion on well-supported facts in
 finding that a skilled artisan would understand the rele-
 vant impurities to be those generated during the alkylation
 and hydrolysis steps used to create the starting batch of
 treprostinil.
     We need not evaluate this argument that claims 1–3 of
 the ’066 patent are not infringed, because Liquidia cor-
 rectly argues that the district court did not clearly err in
 finding those claims invalid as anticipated by Moriarty.
 See Part II.B. Because unpatentable or invalid claims can-
 not be infringed, Commil, 

 (“To say that an
 invalid patent cannot be infringed . . . is in one sense a sim-
 ple truth, both as a matter of logic and semantics.”), the
 issue of infringement of claims 1–3 of the ’066 patent has
 been rendered moot.
                               B.
      Accordingly, we forthwith turn to United Therapeutics’
 argument on cross-appeal concerning the validity of claims
 1–3. United Therapeutics argues that Moriarty does not
 teach the purification of treprostinil through salt formation
 and discloses no information on specific alkylation and hy-
 drolysis impurities. United Therapeutics argues that it
 added the relevant impurities claim language to overcome
 validity challenges raised during prosecution, and the
 court failed to recognize the structural features that are
 imparted by the claimed salt-formation purification.
 United Therapeutics further contends that Moriarty dis-
 closes treprostinil with a purity of 99.7%, which does not
 establish that the product of Moriarty had the same level
 of alkylation or hydrolysis impurities of the claimed prod-
 uct.
      Liquidia responds that the district court did not err in
 finding that claims 1–3, 6, and 9 of the ’066 patent are an-
 ticipated by Moriarty. Liquidia argues that the claimed
 composition in Moriarty is the same as the claimed
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 UNITED THERAPEUTICS CORPORATION     v.                     21
 LIQUIDIA TECHNOLOGIES, INC.


 composition in the ’066 patent, and that United Therapeu-
 tics demonstrated no clear error in the court’s findings.
     We agree with Liquidia that the district court did not
 clearly err in finding that claims 1–3, 6, and 9 are invalid
 as anticipated by Moriarty. The claims of the ’066 patent
 are directed to a pharmaceutical composition comprising,
 inter alia, treprostinil, prepared by alkylation and hydrol-
 ysis steps. It is thus referred to as a product-by-process
 claim. But a product-by-process claim is a product claim,
 even if claimed by a process by which it can be made. The
 claims also recite the presence of impurities.
      We conclude that the district court did not clearly err
 in finding that these claims are anticipated by the Moriarty
 reference, which discloses treprostinil with impurities.
 The specification of the ’066 patent discloses an impurity
 level of 99.7%–99.9%, ’066 patent col. 14, table, whereas
 Moriarty similarly discloses the synthesis of impure
 treprostinil, designated in the publication as UT-15, hav-
 ing 99.7% purity, Moriarty at 1890, 1892, 1902. As these
 claims are product claims, they are anticipated by a disclo-
 sure of the same product irrespective of the processes by
 which they are made. Further, United Therapeutics did
 not provide any expert or fact witness rebutting Liquidia’s
 expert’s opinions or providing testimony identifying any
 structural or functional differences between the Moriarty
 treprostinil and the claimed treprostinil. Decision, at 456.
 The court thus did not err in finding that claims 1–3, 6, and
 9 of the ’066 patent are anticipated by Moriarty.
                              C.
     United Therapeutics also argues on cross-appeal that
 the district court clearly erred in finding that Liquidia does
 not infringe claims 6 and 8 of the ’066 patent. United Ther-
 apeutics contends that claims 6 and 8 require that the
 treprostinil salt be stored at ambient temperature, and
 that Liquidia stores treprostinil salt at ambient tempera-
 ture during production, thus infringing the claims. United
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 22                     UNITED THERAPEUTICS CORPORATION v.
                                LIQUIDIA TECHNOLOGIES, INC.


 Therapeutics contends that Liquidia’s promise not to make
 its product with batches of treprostinil salt that were
 stored at ambient temperature is insufficient to avoid a
 finding of infringement.
     United Therapeutics also contends that the district
 court erred in construing the term “storage” in claims 6 and
 8 as excluding storage during manufacturing but including
 storage during shipment of the product. United Therapeu-
 tics further contends that Liquidia also infringes claim 8
 through ambient storage that occurs after the composition
 recited in claims 1–6 is prepared and before the drug prod-
 uct of claim 8 is prepared.
     Liquidia responds that the district court did not clearly
 err in finding that it does not infringe claims 6 and 8 of the
 ’066 patent. In particular, Liquidia notes that the court
 based its findings of non-infringement on several clear
 findings of fact, including that (1) Liquidia’s NDA requires
 the treprostinil salt to be stored at a temperature of 2–8°C;
 (2) Liquidia asserted that it would not use treprostinil salt
 batches that have been stored at ambient temperature; and
 (3) Liquidia begins preparing a pharmaceutical product
 during step 1 of its production process. Liquidia further
 asserts that the NDA storage specifications are regulatory
 requirements, not mere recommendations or promises.
     Liquidia further responds that the district court did not
 err in its construction of the term “storage.” Liquidia as-
 serts that United Therapeutics mischaracterizes Liquidia’s
 production process, and that its production process is a sin-
 gle production process, not two stages separated by a pe-
 riod of ambient storage.
     We agree with Liquidia that the district court did not
 clearly err in finding that it does not infringe claims 6 and
 8 of the ’066 patent. The court credited Liquidia’s repre-
 sentations to the FDA that it would store treprostinil so-
 dium between 2°C and 8°C. The court also found that
 United Therapeutics provided no evidence showing that
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 UNITED THERAPEUTICS CORPORATION    v.                     23
 LIQUIDIA TECHNOLOGIES, INC.


 Liquidia used ambient-temperature-stored batches of
 treprostinil in its manufacturing process in making a phar-
 maceutical composition as required by claim 6 or claim 8.
 Without a showing that Liquidia stores treprostinil at am-
 bient temperature, there can be no infringement of the
 claims.
                        CONCLUSION
     We have considered the parties’ remaining arguments
 but find them unpersuasive. For the foregoing reasons, the
 decision of the United States District Court for the District
 of Delaware is affirmed.
                        AFFIRMED
                            COSTS
 No costs.