Case: 23-2032   Document: 90     Page: 1   Filed: 09/18/2024




   United States Court of Appeals
       for the Federal Circuit
                 ______________________

  ASTELLAS PHARMA, INC., ASTELLAS IRELAND
     CO., LTD., ASTELLAS PHARMA GLOBAL
             DEVELOPMENT, INC.,
                Plaintiffs-Appellants

                            v.

 SANDOZ INC., ZYDUS PHARMACEUTICALS (USA)
  INC., ZYDUS LIFESCIENCES LTD., DBA ZYDUS
           CADILA, LUPIN LTD., LUPIN
         PHARMACEUTICALS, INC., LEK
            PHARMACEUTICALS, D.D.,
               Defendants-Appellees

     AUROBINDO PHARMA LTD., AUROBINDO
   PHARMA USA, INC., AUROLIFE PHARMA LLC,
      ACTAVIS ELIZABETH LLC, PRINSTON
   PHARMACEUTICAL INC., ZHEJIANG HUAHAI
  PHARMACEUTICAL CO., LTD., HUAHAI US INC.,
    SOLCO HEALTHCARE U.S., LLC, WINDLAS
   HEALTHCARE PVT. LTD., WINDLAS BIOTECH
    LTD., TEVA PHARMACEUTICALS USA, INC.,
                     Defendants
               ______________________

             2023-2032, 2023-2063, 2023-2089
                 ______________________

     Appeals from the United States District Court for the
 District of Delaware in Nos. 1:20-cv-01589-JFB-CJB, 1:21-
 cv-00425-JFB-CJB, 1:21-cv-00664-JFB-CJB, Senior Judge
 Joseph F. Bataillon.
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 2                        ASTELLAS PHARMA, INC. v. SANDOZ INC.




                  ______________________

                Decided: September 18, 2024
                  ______________________

     PAUL WHITFIELD HUGHES, III, McDermott Will & Em-
 ery LLP, Washington, DC, argued for plaintiffs-appellants.
 Also represented by ANDREW LYONS-BERG, CHARLES H.
 SEIDELL; JASON ALBERT LEONARD, SIMON ROBERTS, New
 York, NY; DANIEL M. SILVER, McCarter & English, LLP,
 Wilmington, DE.

     WILLIAM R. ZIMMERMAN, Knobbe, Martens, Olson &
 Bear, LLP, Washington, DC, argued for all defendants-ap-
 pellees. Defendants-appellees Lupin Ltd., Lupin Pharma-
 ceuticals, Inc. also represented by ANDREA L. CHEEK;
 CAROL PITZEL CRUZ, Seattle, WA.

     KEVIN PATRICK BURKE, Rakoczy Molino Mazzochi
 Siwik LLP, Chicago, IL, for defendants-appellees Sandoz
 Inc., Lek Pharmaceuticals, d.d. Also represented by
 DEANNE M. MAZZOCHI, WILLIAM A. RAKOCZY, RACHEL
 PERNIC WALDRON.

     MICHAEL GAERTNER, Locke Lord LLP, Chicago, IL, for
 defendants-appellees Zydus Pharmaceuticals (USA) Inc.,
 Zydus Lifesciences Ltd. Also represented by DAVID BRIAN
 ABRAMOWITZ, HUGH S. BALSAM, CAROLYN ANNE BLESSING,
 EMILY SAVAS, JONATHAN B. TURPIN.
                  ______________________

     Before LOURIE, PROST, and REYNA, Circuit Judges.
 LOURIE, Circuit Judge.
     Astellas Pharma, Inc., Astellas Ireland Co., Ltd., and
 Astellas Pharma Global Development, Inc. (collectively,
 “Astellas”) appeal from the final judgment of the United
 States District Court for the District of Delaware.
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 ASTELLAS PHARMA, INC. v. SANDOZ INC.                       3



 Following a five-day bench trial on issues of infringement
 and validity under 

, the district court deter-
 mined, sua sponte, that claims 5, 20, and 25 of U.S. Patent
 10,842,780 (“the ’780 patent”) are invalid under 

 as directed to an ineligible natural law. Astellas
 Pharma Inc. v. Sandoz Inc., No. 20-cv-1589, 

 (D. Del. June 9, 2023) (“Decision”). For the rea-
 sons set forth below, we vacate the judgment and remand.
                        BACKGROUND
                               I
     In 2012, the U.S. Food and Drug Administration
 (“FDA”) approved the New Drug Application (“NDA”) for
 extended-release mirabegron tablets for the treatment of
 overactive bladder (“OAB”), which Astellas markets and
 sells under the brand name Myrbetriq®. Mirabegron is a
 beta-3 agonist that stimulates beta receptors in the blad-
 der, thereby inducing bladder relaxation and improving
 bladder function.
     During the development of Myrbetriq, Astellas discov-
 ered that immediate-release formulations of mirabegron
 exhibit an undesirable “food effect,” meaning that the bio-
 availability of the drug is affected by the presence or ab-
 sence of food in a patient’s stomach. Astellas observed that
 when patients took the drug with a meal, the levels of mir-
 abegron that were absorbed into the blood were too low to
 impart any therapeutic benefit. But when patients took
 the drug on an empty stomach, mirabegron was absorbed
 too rapidly, reaching potentially toxic concentrations in the
 blood. To solve this problem, Astellas developed sustained-
 release formulations of mirabegron, which abated the un-
 desirable food effect. Those formulations are covered by
 the claims of the ’780 patent.
     The ’780 patent contains two independent claims, each
 of which is directed to a sustained-release pharmaceutical
 composition comprising mirabegron. Independent claim 1,
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 4                       ASTELLAS PHARMA, INC. v. SANDOZ INC.




 from which asserted claims 5 and 20 ultimately depend, re-
 cites:
     1. A pharmaceutical composition, comprising 10
     mg to 200 mg of [mirabegron], or a pharmaceuti-
     cally acceptable salt thereof, in a sustained release
     hydrogel-forming formulation comprising a hydro-
     gel-forming polymer having an average molecular
     weight of 100,000 to 8,000,000 and an additive hav-
     ing a water solubility of at least 0.1 g/mL at 20±5°
     C.,
     wherein the hydrogel-forming polymer is at least
     one compound selected from the group consisting of
     polyethylene oxide, hydroxypropyl methylcellulose,
     hydroxypropyl cellulose, carboxymethyl cellulose
     sodium, hydroxyethyl cellulose, and a carboxyvinyl
     polymer,
     wherein the additive is at least one selected from
     the group consisting of polyethylene glycol, polyvi-
     nylpyrrolidone, D-mannitol, D-sorbitol, xylitol, lac-
     tose, sucrose, anhydrous maltose, D-fructose,
     dextran, glucose, polyoxyethylene hydrogenated
     castor oil, polyoxyethylene polyoxypropylene gly-
     col, polyoxyethylene sorbitan higher fatty acid es-
     ter, sodium chloride, magnesium chloride, citric
     acid, tartaric acid, glycine, β-alanine, lysine hydro-
     chloride, and meglumine, and
     wherein a drug dissolution rate from the pharma-
     ceutical composition is 39% or less after 1.5 hours,
     and at least 75% after 7 hours, as measured in ac-
     cordance with United States Pharmacopoeia in 900
     mL of a USP buffer having a pH of 6.8 at a paddle
     rotation speed of 200 rpm.
 ’780 patent at col. 20, ll. 19–47; J.A. 8617–18 (Certificate of
 Correction). Asserted claim 5, which depends directly from
 claim 1, recites:
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 ASTELLAS PHARMA, INC. v. SANDOZ INC.                         5



     5. The pharmaceutical composition according to
     claim 1, wherein the hydrogel-forming polymer is
     at least one compound selected from the group con-
     sisting of polyethylene oxide, hyd[r]oxypropyl
     methylcellulose, and hydroxypropyl cellulose.
 ’780 patent at col. 20, ll. 61–65; J.A. 8617–18 (Certificate of
 Correction). Asserted claim 20, which depends from claim
 1 by way of claims 16 and 18, recites:
     20. A method for treating overactive bladder com-
     prising administering the tablet according to claim
     18 to a subject in need thereof.
 ’780 patent at col. 22, ll. 6–8. Claim 18 recites “[a] tablet,
 comprising the pharmaceutical composition according to
 claim 16,” 

 at col. 22, ll. 1–2, and claim 16 recites “[t]he
 pharmaceutical composition according to claim 1, compris-
 ing 10 mg to 200 mg of [mirabegron],” 

 at col. 21, ll.
 30–33.
    Independent claim 22, from which asserted claim 25 ul-
 timately depends, recites:
     22. A pharmaceutical composition, comprising 10
     mg to 200 mg of [mirabegron], or a pharmaceuti-
     cally acceptable salt thereof, in a sustained release
     hydrogel-forming formulation comprising a means
     for forming a hydrogel and a means for ensuring
     penetration of water into the pharmaceutical com-
     position,
     wherein a drug dissolution rate from the pharma-
     ceutical composition is 39% or less after 1.5 hours,
     and at least 75% after 7 hours, as measured in ac-
     cordance with United States Pharmacopoeia in 900
     mL of a USP buffer having a pH of 6.8 at a paddle
     rotation speed of 200 rpm.
 

 at col. 22, ll. 13–25. Asserted claim 25, which depends
 from independent claim 22 by way of claim 23, recites:
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 6                       ASTELLAS PHARMA, INC. v. SANDOZ INC.




     25. A tablet, comprising the pharmaceutical com-
     position according to claim 23.
 

 at col. 22, ll. 32–33. Claim 23 recites “[t]he pharmaceu-
 tical composition according to claim 22, comprising 10 mg
 to 200 mg of [mirabegron].” 

 at col. 22, ll. 26–29.
     In short, asserted claims 5, 20, and 25 are generally di-
 rected to a pharmaceutical composition comprising mira-
 begron, a method of treating OAB using that composition,
 and a tablet comprising that composition, respectively.
                               II
      On November 24, 2020, the day that the ’780 patent
 issued, Astellas sued each of Sandoz Inc., Zydus Pharma-
 ceuticals (USA) Inc., Zydus Lifesciences Ltd., dba Zydus
 Ca-Dila, Lupin Ltd., Lupin Pharmaceuticals, Inc., and Lek
 Pharmaceuticals, D.D. (collectively, “Sandoz”) for patent
 infringement under 

(e)(2)(A) based on the
 Abbreviated New Drug Application (“ANDA”) each had
 submitted in 2016, seeking FDA approval to market and
 sell generic versions of Myrbetriq. 1 The cases were consol-
 idated and proceeded to discovery.
     On July 7, 2021, Sandoz produced its initial invalidity
 contentions. See J.A. 651–52. In those contentions, Sandoz
 claimed that the asserted claims were invalid under each
 of 

 (for anticipation), 103 (for obviousness),
 and 112 (for each of written description, enablement, and
 indefiniteness). Astellas Br. 11–12. Over a year later, on
 August 29, 2022, Sandoz produced its final invalidity con-
 tentions, maintaining each of those same grounds of



     1    Astellas previously sued Sandoz in 2016 for in-
 fringement of certain then-listed Orange Book patents.
 E.g., Astellas Pharma Inc. v. Sandoz Inc., No. 16-cv-952 (D.
 Del. filed Oct. 14, 2016). But the parties thereafter reached
 a settlement, and those cases were dismissed.
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 ASTELLAS PHARMA, INC. v. SANDOZ INC.                        7



 invalidity. 

; J.A. 1501–02. Sandoz did not pursue
 an invalidity defense under 

 during the dis-
 covery phase of the litigation.
      Nearing the February 6, 2023 trial date, the parties
 continued to narrow their theories of the case. In mid-Jan-
 uary, the parties filed a joint proposed pre-trial order, in
 which Sandoz agreed to limit its invalidity defenses to ob-
 viousness under 

 and each of written de-
 scription, enablement, and indefiniteness under § 112. See
 generally J.A. 6505–36 (Sandoz’s Statement of Issues of
 Law that Remain to be Litigated). Then, on February 1,
 2023, the parties filed a joint stipulation in which Astellas
 agreed to assert only claims 5, 20, and 25 of the ’780 patent,
 while Sandoz agreed to limit its invalidity defenses to only
 those arising under § 112. J.A. 6591–93. Accordingly, in
 the days leading up to trial, Sandoz waived any challenge
 to the asserted claims arising under §§ 102 and 103. The
 five-day bench trial came and went with no discussion, let
 alone argument, from the parties as to the patent eligibility
 of the asserted claims. Nor did that issue arise in the par-
 ties’ post-trial briefing.
     Nevertheless, the district court issued a final decision
 holding asserted claims 5, 20, and 25 of the ’780 patent in-
 valid as directed to patent-ineligible subject matter under
 

. Decision at *2. Relying on Astellas’s state-
 ment in its post-trial briefing, that, in the context of ena-
 blement under § 112, the “inventive concept of the ’780
 Patent was discovering the dissolution rate that would ad-
 dress the food effect and achieving it using previously
 known formulation technology,” id. (quoting Astellas’s
 post-trial rebuttal brief, J.A. 7416) (emphases omitted), the
 district court determined that “Astellas concedes that the
 ’780 patent is enabled because it claims invalid subject
 matter: a natural law applied via routine, conventional,
 and well-known methods.” Id. (citing Mayo Collaborative
 Servs. v. Prometheus Lab’ys, Inc., 

 (2012)).
 Thus, because the claimed invention “reflects merely the
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 8                       ASTELLAS PHARMA, INC. v. SANDOZ INC.




 discovery of the food-effect-resolving dissolution profile,”
 the district court deemed the asserted claims invalid as pa-
 tent ineligible. Id. at *1.
      Following the entry of judgment, Sandoz, the prevail-
 ing party, moved pursuant to Federal Rule of Civil Proce-
 dure 52(b) for the district court to make additional findings
 of fact and conclusions of law on the issues actually pre-
 sented at trial—namely, infringement and validity under
 § 112. J.A. 8507–11. In that motion, Sandoz argued that
 it anticipated that Astellas would appeal the judgment and
 argue that “a § 101 defense [] was not presented at trial or
 in the post-trial briefing” and that the defense “is currently
 not set forth in the [c]ourt’s opinion in terms of the claim
 language itself.” Id. at 8508–09 (citing Synopsys, Inc. v.
 Mentor Graphics Corp., 

 (Fed. Cir.
 2016), for the proposition that a § 101 inquiry must be
 based on the language of the claims themselves). The dis-
 trict court denied that motion, concluding that, despite
 Sandoz’s concerns, “[t]he [c]ourt could not have better in-
 voked [Mayo].” Astellas Pharma Inc. v. Sandoz Inc., No.
 20-cv-1589 (D. Del. June 27, 2023), ECF 577, J.A. 8512–14
 (“Rule 52(b) Decision”).
    Astellas timely appealed. We have jurisdiction under
 

(a)(1).
                         DISCUSSION
                               I
     The Supreme Court has made clear that, “[i]n our ad-
 versary system, in both civil and criminal cases, in the first
 instance and on appeal, we follow the principle of party
 presentation. That is, we rely on the parties to frame the
 issues for decision and assign to courts the role of neutral
 arbiter of matters the parties present.” Greenlaw v. United
 States, 

 (2008). By rendering its decision
 on a ground not raised by any party at any stage of the pro-
 ceedings, and by expressly declaring that it “sits not [as] an
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 ASTELLAS PHARMA, INC. v. SANDOZ INC.                        9



 arbiter to resolve the disputes on the parties’ favored ter-
 rain,” Decision at *2, the district court disregarded the
 longstanding principle of party presentation and, in doing
 so, abused its discretion. United States v. Sineneng-Smith,
 

 (2020) (providing that departures from
 the principle of party presentation are reviewed for abuse
 of discretion); United States v. Dowdell, 

 (3d Cir. 2023) (same); see Innogenetics, N.V. v. Abbott
 Lab’ys, 

 (Fed. Cir. 2008) (“We review
 procedural issues not unique to patent law under regional
 circuit law.”).
     To be sure, “[t]he party presentation principle is sup-
 ple, not ironclad,” and there are circumstances in which it
 may be appropriate for a court to take a “modest initiating
 role” in the shape of the litigation. Sineneng-Smith,
 

. But rendering a patent invalid on a basis
 not advanced by any party is not such a circumstance.
      One cornerstone of patent litigation lies in 

, which provides that “[a] patent shall be presumed
 valid” and that “[t]he burden of establishing invalidity of a
 patent or any claim thereof shall rest on the party assert-
 ing such invalidity.” That statutory prescription mandates
 that the party asserting an invalidity defense must prove
 that defense by clear and convincing evidence. Microsoft
 Corp. v. I4I Ltd. P’ship, 

 (2011). It thus fol-
 lows that, in a court proceeding, a patent is not found
 “valid.” See Panduit Corp. v. Dennison Mfg. Co., 

 (Fed. Cir. 1987) (“It is neither necessary nor ap-
 propriate for a court to declare a patent valid.”) (citing
 Env’t Designs, Ltd. v. Union Oil Co. of Cal., 

,
 699 n.9 (Fed. Cir. 1984)). Rather, when a patent owner
 prevails in the face of an invalidity defense or counter-
 claim, it merely means that the patent challenger has
 failed to carry its burden of establishing, in that particular
 case, invalidity by clear and convincing evidence. See 

 at 1569–70; accord Shelcore, Inc. v. Durham Indus., Inc.,
 

 (Fed. Cir. 1984) (“A patent is not held
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 10                      ASTELLAS PHARMA, INC. v. SANDOZ INC.




 valid for all purposes but, rather, not invalid on the record
 before the court.”). By statute then, the court’s role in is-
 sues of patentability is straightforward. It “does not re-
 quire [the court] to conclude whether something was or was
 not ‘invented’, or whether the court subjectively considers
 the invention ‘worthy’ of patent protection.” Lindemann
 Maschinenfabrik GMBH v. Am. Hoist & Derrick Co.,
 

, 1457 n.1 (Fed. Cir. 1984). Rather, the
 court’s role is simply “to determine whether the patent’s
 challenger carried the burden of establishing invalidity.”
 

      Here, the district court appears to have misappre-
 hended its role in adjudicating the issue of patentability.
 It interpreted Astellas’s “zealous defense” on issues of § 112
 as “conced[ing] that the ’780 patent is enabled because it
 claims invalid subject matter: a natural law applied via
 routine, conventional, and well-known methods.” Decision
 at *1. It then used that “concession” to hold the patent in-
 valid on a ground never advanced by Sandoz. That was an
 abuse of discretion. Curiously, the district court did appear
 to appreciate that the issue of patent eligibility was not as-
 serted by Sandoz. In its denial of Sandoz’s Rule 52(b) mo-
 tion, the court acknowledged Sandoz’s “worry [that] the
 parties inadequately raised the matter of subject-matter el-
 igibility at trial or in briefing.” Rule 52(b) Decision,
 J.A. 8512. But it deemed that worry unwarranted because
 of the “fundamental flaw” it sensed “in the [parties’] asser-
 tion that patent litigants may, in essence, consent around
 the bounds of patent eligibility.” Id. And therein lies the
 problem. It is for the parties—not the court—to chart the
 course of the litigation. See Lannom Mfg. Co. v. U.S. Int’l
 Trade Comm’n, 

 (Fed. Cir. 1986) (“It is
 beyond cavil that a district court does not have authority
 to invalidate a patent at its own initiative if validity is not
 challenged by a party.”).
      Further, the district court’s treatment of patent eligi-
 bility suffered from its own “fundamental flaw.” It appears
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 ASTELLAS PHARMA, INC. v. SANDOZ INC.                       11



 that the district court believed patent eligibility under
 

 to be a threshold inquiry that it had a duty
 to address—even in the silence of the parties—akin to, for
 example, subject-matter jurisdiction. But the presumption
 of validity afforded to patents under § 282 applies equally
 to all grounds of validity, including the eligibility of the
 claimed subject-matter. Cellspin Soft, Inc. v. Fitbit, Inc.,
 

 (Fed. Cir. 2019) (“Th[e] presumption
 reflects the fact that the Patent and Trademark Office has
 already examined whether the patent satisfies ‘the prereq-
 uisites for issuance of a patent,’ including § 101.” (quoting
 Microsoft, 564 U.S. at 95–96)). 2 Accordingly, to the extent
 the district court believed that validity under § 101 is
 treated any differently than validity under §§ 102, 103, and
 112 for purposes of the party presentation principle, that
 was error.
     Sandoz’s attempts to excuse the district court’s depar-
 ture from that principle are unavailing. In its view, the
 district court acted within its authority in light of prece-
 dent and Astellas’s “stunning admissions” at trial regard-
 ing the invention. Sandoz Br. 23. Relying on cases from
 the late 1800s and certain non-binding out-of-circuit
 cases, 3 Sandoz argues that “[t]he Supreme Court has long



     2    To be sure, § 101 is a threshold inquiry in obtaining
 patent protection. See In re Comiskey, 

 (Fed. Cir. 2009) (explaining, in the context of patent prose-
 cution, that “[o]nly if the requirements of § 101 are satis-
 fied is the inventor allowed to pass through to the other
 requirements for patentability, such as novelty under § 102
 and . . . non-obviousness under § 103” (internal quotation
 marks and citation omitted)).
     3    Sandoz also relies on Comiskey for the proposition
 that the Federal Circuit has “considered § 101 issues with-
 out prompting from the parties.” Sandoz Br. 20–21.
 Comiskey was an appeal from a decision of the Board of
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 12                      ASTELLAS PHARMA, INC. v. SANDOZ INC.




 held that a court may consider the eligibility or validity of
 a patent, even if such a defense is not raised by the defend-
 ant in the action.” Id. at 18 (citing Slawson v. Grand Street,
 P.P & F.R. Co., 

 (1883); Brown v. Piper,
 

, 43–44 (1875); Dunbar v. Myers, 

 (1876)); see 

 at 19–20 (citing Barkeij v. Lockheed Air-
 craft Corp., 

 (9th Cir. 1954); Howes v. Great
 Lakes Press Corp., 

 (2d Cir. 1982)). But
 those decisions were rendered before, or did not address the
 impact of, the Patent Act of 1952’s codification of a patent’s
 presumption of validity and the requirement that a patent
 challenger affirmatively plead its defenses. See 

, 

, 812 (1952) (codified at
 

). We therefore find Sandoz’s reliance on
 those cases unpersuasive. 4




 Patent Appeals and Interferences (“Board”), determining
 that a patent application was unpatentable under § 103.
 

. We affirmed the Board’s judgment of un-
 patentability under § 101. Id. While neither the examiner
 nor the Board had made a patentability determination un-
 der § 101, we confirmed that both the APA and the Su-
 preme Court’s decision in SEC v. Chenery Corp., 

 (1943), “made clear that a reviewing court can (and
 should) affirm an agency decision on a legal ground not re-
 lied on by the agency if there is no issue of fact, policy, or
 agency expertise.” Id. at 974 (emphases added). The APA
 and Chenery principles that existed in Comiskey do not ex-
 ist in the present case.
      4   For the first time at oral argument, Sandoz argued
 that it did plead an invalidity defense under § 101, refer-
 encing each Defendant-Appellee’s answer to Astellas’s
 complaint. See Oral Arg. at 16:42–57, available at
 https://oralarguments.cafc.uscourts.gov/default.aspx?fl=23
 -2032_08072024.mp3 (counsel for Sandoz arguing that
 “[t]he answers contain affirmative defenses under § 101,
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 ASTELLAS PHARMA, INC. v. SANDOZ INC.                       13



       Sandoz’s invocation of public policy to justify the dis-
 trict court’s decision is no more persuasive. Sandoz
 Br. 23–24 (arguing that the “public has a strong interest in
 the elimination of invalid pharmaceutical patents that de-
 lay or deter low-cost generic alternatives”). That argument
 is entirely irrelevant to the scope of a court’s authority to
 stray from the case as designed by the parties. Indeed, we
 have long rejected such “public responsibility” concerns in
 favor of adherence to the party presentation principle. See
 Lannom Mfg., 

 (rejecting argument that
 the International Trade Commission has a public respon-
 sibility to “verify the validity of any patent brought before
 it”).
     Accordingly, because the district court abused its dis-
 cretion in holding the asserted claims invalid under
 

, a ground not invoked by Sandoz, we vacate
 the judgment and remand for adjudication of the issues
 properly raised and adequately supported by the record.
 Those issues are limited to infringement and validity under
 

. See J.A. 6591–93.
                               II
     We turn now to Astellas’s request that this case be re-
 assigned to a different district court judge on remand. As-
 tellas argues that “[t]aken together, the district court’s two
 post-trial decisions are rather extraordinary,” Astellas
 Br. 55, such that reassignment is necessary to maintain an
 appearance of impartiality and fairness in the forthcoming
 remand proceedings.



 and Lupin’s [counterclaim] has an express statement un-
 der § 101”). Sandoz did not raise that argument anywhere
 on appeal. Thus, it is forfeited. See Becton Dickinson &
 Co. v. C.R. Bard, Inc., 

 (Fed. Cir. 1990)
 (noting we have discretion to consider arguments not
 raised in a party’s appellate brief).
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 14                      ASTELLAS PHARMA, INC. v. SANDOZ INC.




      Reassignment is “an exceptional remedy, one that we
 weigh seriously and order sparingly.” United States v. Ken-
 nedy, 

 (3d Cir. 2012); see Lazare Kaplan
 Int’l, Inc. v. Photoscribe Techs., Inc., 

 (Fed. Cir. 2013) (providing that reassignment requests are
 evaluated “under the law of the regional circuit in which
 the district court sits”). When reviewing requests for reas-
 signment, the Third Circuit applies “a standard that calls
 for reassignment when a reasonable person, with
 knowledge of all the facts, would conclude that the judge’s
 impartiality might reasonably be questioned.” Arrowpoint
 Cap. Corp. v. Arrowpoint Asset Mgmt., LLC, 

 (3d Cir. 2015) (internal quotation marks and citations
 omitted). Having considered the parties’ arguments and
 having undertaken our own review of the district court pro-
 ceedings, we decline to order the extraordinary remedy of
 reassignment in this case.
     Astellas first argues that the district court’s failure to
 abide by the party presentation principle is, “standing
 alone,” enough to warrant reassignment. See Astellas Br.
 55–56. We disagree. The Third Circuit has made clear that
 “adverse rulings—even if they are erroneous—are not in
 themselves proof of prejudice or bias” that warrant judicial
 reassignment. Arrowpoint, 

. We have al-
 ready concluded that the district court abused its discre-
 tion, as a matter of procedure, in rendering its judgment.
 And, although we have serious doubts that, on the merits,
 the asserted claims—directed to nonnatural compositions
 of matter and associated methods of use—are ineligible for
 patent protection (an issue we decline to resolve), those
 kinds of errors, i.e., errors relating to the propriety of the
 district court’s analysis, are insufficient to warrant reas-
 signment.
      Astellas next points to various statements that the dis-
 trict court made in its two decisions on appeal as evidenc-
 ing judicial bias. For example, in its denial of Sandoz’s
 Rule 52(b) motion, the district court stated that “[t]he
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 ASTELLAS PHARMA, INC. v. SANDOZ INC.                      15



 pharmaceutical industry, to put it mildly, has perverted
 th[e] intent [of the Hatch-Waxman Amendments]. With
 alarming regularity since, brand and generic drug manu-
 facturers have colluded to protect weak or invalid patents
 and share in the startling profits.” Rule 52(b) Decision,
 J.A. 8513 (citing an unrelated antitrust litigation concern-
 ing the sale of a type 2 diabetes drug). The district court
 further stated that this “case is about the pharmaceutical
 industry’s long-standing ‘innovation’ of patenting ex-
 tended-release formulas for soon-to-expire active-ingredi-
 ent patents,” a practice the district court believes the U.S.
 Patent and Trademark Office has “accommodated” by issu-
 ing patents to such inventions. 

      We agree with Astellas that these statements have no
 relevance to the proceedings in this case, which are limited
 to the issues of infringement and validity under 

 of three claims of the ’780 patent. We further under-
 stand Astellas’s concern that the district court’s commen-
 tary may evidence a personal frustration with the
 pharmaceutical industry as a whole. See also Sandoz Br.
 43 (“And to the extent that the district court’s opinions ex-
 pressed a frustration with the pharmaceutical industry,
 both ‘brand and generic manufacturers’ were mentioned.”).
 To be sure, these proceedings are not an appropriate venue
 for those frustrations to be aired, let alone acted upon. See
 Sineneng-Smith, 

 (“[Courts] do not, or
 should not, sally forth each day looking for wrongs to
 right.” (internal quotation marks and citation omitted)).
      Although we have concerns with the analysis of the dis-
 trict court, we are not convinced that the judge, who has
 overseen nearly two hundred patent cases and has ruled in
 favor of both innovative and generic manufacturers alike,
 cannot resolve the outstanding issues impartially and
 fairly, particularly now that we have clarified the proper
 course for adjudication. Significantly, other than the
 court’s two rulings, Astellas cannot identify any instance
 in the life of this nearly four-year-old litigation in which
Case: 23-2032    Document: 90      Page: 16    Filed: 09/18/2024




 16                      ASTELLAS PHARMA, INC. v. SANDOZ INC.




 the district court judge acted in a way that called into ques-
 tion his ability to do just that. Further, as Sandoz points
 out, the district court judge is currently presiding over two
 related cases that concern the same or similar validity is-
 sues on similar subject matter. See Sandoz Br. 48 n.6.
     Ultimately, we trust that, upon remand, the district
 court can and will take an objective, measured, and thor-
 ough look into the legal issues and evidence of record to
 resolve only those disputes that exist between the parties.
                         CONCLUSION
      We have considered the parties’ remaining arguments
 and find them unpersuasive. For the reasons set forth
 above, we vacate the district court’s judgment and remand
 for adjudication of the case as it was shaped by the parties.
                VACATED AND REMANDED
                            COSTS
 No costs.