Court Opinion

ID: 9959326
Source: CourtListenerOpinion
Date Created: 2024-04-11 16:01:02.439695+00
Date Added: 2024-06-11T08:18:16.389584
License: Public Domain

Case: 22-2153    Document: 71     Page: 1   Filed: 04/11/2024

   United States Court of Appeals
       for the Federal Circuit
                  ______________________

     SALIX PHARMACEUTICALS, LTD., SALIX
   PHARMACEUTICALS, INC., BAUSCH HEALTH
       IRELAND LTD., ALFASIGMA S.P.A.,
              Plaintiffs-Appellants

                             v.

        NORWICH PHARMACEUTICALS INC.,
             Defendant-Cross-Appellant
              ______________________

                   2022-2153, 2023-1952
                  ______________________

     Appeals from the United States District Court for the
 District of Delaware in No. 1:20-cv-00430-RGA, Judge
 Richard G. Andrews.
                 ______________________

                  Decided: April 11, 2024
                  ______________________

     WILLIAM R. PETERSON, Morgan, Lewis & Bockius LLP,
 Houston, TX, argued for plaintiffs-appellants. Also repre-
 sented by MICHAEL J. ABERNATHY, KARON NICOLE FOWLER,
 MICHAEL SIKORA, Chicago, IL; JULIE S. GOLDEMBERG, Phil-
 adelphia, PA; JOSHUA DANIEL CALABRO, SHANNON KEOUGH
 CLARK, STEVEN C. KLINE, ALEXIS M. MCJOYNT, SCOTT K.
 REED, BECKY E. STEEPHENSON, Venable LLP, New York,
 NY.

    CHAD A. LANDMON, Axinn, Veltrop & Harkrider LLP,
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                              NORWICH PHARMACEUTICALS INC.

 Hartford, CT, argued for defendant-cross-appellant. Also
 represented by MATTHEW BECKER, REBECCA L. CLEGG,
 THOMAS K. HEDEMANN, MATTHEW S. MURPHY.

     IRENA ROYZMAN, Kramer Levin Naftalis & Frankel
 LLP, New York, NY, for amici curiae Regeneron Pharma-
 ceuticals, Inc., Ocular Therapeutix, Inc. Also represented
 by CHRISTINE WILLGOOS; PAUL BRZYSKI, Washington, DC.

     PAUL WHITFIELD HUGHES, III, McDermott Will & Em-
 ery LLP, Washington, DC, for amicus curiae Vanda Phar-
 maceuticals Inc.   Also represented by CHRISTOPHER
 MICHAEL BRUNO, SARAH HOGARTH, APRIL ELISE
 WEISBRUCH.
                 ______________________

  Before LOURIE, CHEN, and CUNNINGHAM, Circuit Judges.
     Opinion for the court filed by Circuit Judge LOURIE.
      Opinion dissenting-in-part filed by Circuit Judge
                       CUNNINGHAM.
 LOURIE, Circuit Judge.
     Salix Pharmaceuticals, Ltd., Salix Pharmaceuticals,
 Inc., Bausch Health Ireland Ltd., and Alfasigma S.P.A.
 (collectively, “Salix”) appeal from a final judgment of the
 United States District Court for the District of Delaware
 holding claim 2 of U.S. Patent 8,309,569, claim 3 of U.S.
 Patent 10,765,667, claim 4 of U.S. Patent 7,612,199, and
 claim 36 of U.S. Patent 7,902,206 invalid as obvious. See
 Salix Pharms., Ltd. v. Norwich Pharms., Inc., No. 20-cv-
 430, 2022 WL 3225381 (D. Del. Aug. 10, 2022) (“Decision”).
    Norwich Pharmaceuticals Inc. (“Norwich”) cross-ap-
 peals from an order that issued after the district court con-
 cluded that Norwich infringed claim 8 of U.S. Patent
 8,624,573, claim 6 of U.S. Patent 9,421,195, and claims 11
 and 12 of U.S. Patent 10,335,397 and had failed to prove
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 that those claims were invalid. That order, contained
 within the final judgment, instructed the FDA that the ef-
 fective approval date of Norwich’s Abbreviated New Drug
 Application (“ANDA”) may not precede the expiration dates
 of those claims. J.A. 51. Norwich also cross-appeals from
 a denial of its motion to modify the final judgment. See
 Salix Pharms., Ltd. v. Norwich Pharms., Inc., No. 20-430,
 2023 WL 3496373 (D. Del. May 17, 2023) (“Rule 60(b) Or-
 der”).
    For the following reasons, we affirm.
                        BACKGROUND
     Rifaximin, the active ingredient in Salix’s commercial
 product Xifaxan®, has been widely used as an antibiotic for
 decades, having been first synthesized in the early 1980s
 in Italy and approved there as an antibiotic in 1985. Deci-
 sion at *8; J.A. 2532. The FDA approved Xifaxan nearly 20
 years later, in 2004, as 200 mg tablets for the treatment of
 travelers’ diarrhea. Decision at *1. The FDA subsequently
 approved 550 mg tablets for hepatic encephalopathy (“HE”)
 in 2010 and for irritable bowel syndrome with diarrhea
 (“IBS-D”) in 2015. Id.
     Norwich sought to market a generic version of rifaximin
 and, in 2019, filed an ANDA for 550 mg tablets with the
 same indications as Xifaxan, certifying pursuant to
 21 U.S.C. § 355(j)(2)(vii)(IV) that Salix’s rifaximin patents
 were invalid. Salix timely sued, asserting that Norwich’s
 ANDA infringed dozens of valid, Orange Book-listed pa-
 tents. By the time of trial, the case had been streamlined
 to three groups of patents:
    •   the ’573, ’195, and ’397 patents, directed to treating
        HE (“the HE patents”);
    •   the ’569 and ’667 patents, directed to treating IBS-D
        with 550 mg rifaximin three times a day (1,650
        mg/day) for 14 days (“the IBS-D patents”); and,
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     •   the ’199 and ’206 patents, directed to rifaximin form
         β (“the polymorph patents”).
     Following a bench trial, the district court held that
 Norwich infringed the HE patents’ claims and had failed to
 establish their invalidity. Decision at *10−11. Norwich did
 not appeal those holdings. The court also held that Nor-
 wich’s ANDA infringed the IBS-D and polymorph patents,
 but that those patents’ claims would have been obvious
 over certain prior art. Id. at *2−3, 16−17. Salix appealed
 those invalidity holdings.
     As part of the entered judgment, the district court or-
 dered that the effective date of a final approval of Norwich’s
 ANDA should not precede October 2029, which is the latest
 expiration date associated with the HE patents. J.A. 51.
 Norwich then amended its ANDA in an attempt to remove
 the infringing HE indication and moved to modify the judg-
 ment under Federal Rule of Civil Procedure 60(b), assert-
 ing that the amendment negated any possible
 infringement. The court denied Norwich’s motion, and
 Norwich cross-appealed.
     We have jurisdiction under 28 U.S.C. § 1295(a)(1).
                          DISCUSSION
      Salix first contends that the district court’s conclusion
 that the asserted claims of the IBS-D patents were invalid
 as obvious was reached in error. Subsumed within that
 challenge is a question of whether or not a background ref-
 erence discussed by the court was properly established as
 prior art. Salix also contends that the court erred in hold-
 ing that the asserted polymorph patent claims were invalid
 as obvious. Norwich’s cross-appeal asserts that the court
 erred in the phrasing of its order precluding final approval
 of its ANDA until expiration of the HE patents. Norwich
 further asserts that the court erred in denying its motion
 to modify after the ANDA was amended in an attempt to
 avoid infringement. We address each argument in turn.
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                               I
     We turn first to Salix’s contention that the district
 court erred in concluding that the asserted claims of the
 IBS-D patents would have been obvious over the asserted
 prior art.
      Whether or not a claim would have been obvious is a
 question of law, based on underlying factual determina-
 tions. Hospira, Inc. v. Fresenius Kabi USA, LLC, 946 F.3d
 1322, 1328–29 (Fed. Cir. 2020). We review the ultimate
 legal question of obviousness de novo and the underlying
 factual determinations for clear error. Id. at 1328. A find-
 ing is clearly erroneous only if we are “left with a definite
 and firm conviction that the district court was in error.” Id.
 (citations omitted).
     The IBS-D patents are directed to treating IBS-D with
 550 mg rifaximin, thrice-daily (1,650 mg/day), for 14 days.
 For example, claim 2 of the ’569 patent depends from claim
 1 as follows:
     1. A method of providing acute treatment for diar-
     rhea-associated Irritable Bowel Syndrome (dIBS)
     comprising: administering 1650 mg/day of rifaxi-
     min for 14 days to a subject in need thereof,
     wherein removing the subject from treatment after
     the 14 days results in a durability of response,
     wherein the durability of response comprises about
     12 weeks of adequate relief of symptoms.
     2. The method of claim 1, wherein the 1650 mg is
     administered at 550 mg three times per day.
 ’569 patent, col. 30 ll. 4–12 (emphases added); see also ’667
 patent, col. 46 ll. 29–33, 39–40 (claims 1 & 3, similar). The
 key limitation on appeal is the dosage amount that appears
 in the claims: 550 mg, three times per day (“TID”), for a
 total of 1,650 mg/day.
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      Norwich challenged the IBS-D claims’ validity by as-
 serting as prior art references a clinical trial protocol that
 had been published on the ClinicalTrials.gov website in
 2005 (“the Protocol”) 1 and a 2006 journal article (“Pimen-
 tel”). 2 The Protocol describes a Phase II study evaluating
 twice-daily doses of 550 mg (1,100 mg/day) and 1,100 mg
 (2,200 mg/day) for 14 and 28 days for the treatment of IBS-
 D. See J.A. 7051. Pimentel teaches administering 400 mg,
 TID (1,200 mg/day), for the treatment of IBS, 3 but further
 opines that the “optimal dosage of rifaximin may, in fact,
 be higher than that used in our study.” J.A. 4644.
     The district court found that those two references dis-
 close each and every limitation of the challenged IBS-D
 claims, and further found that a skilled artisan would have
 been motivated to combine those two references to arrive
 at what is claimed with a reasonable expectation of success.
 Decision at *17, *19–20. The court then concluded that the
 challenged IBS-D claims were invalid as obvious. Id. at

     1    ClinicalTrials.gov, History of Changes for Study:
 NCT00269412, Randomized, Double Blind, Placebo-Con-
 trolled Study to Assess the Efficacy and Safety of Three Dif-
 ferent Doses of Rifaximin Administered BID either Two or
 Four Weeks in the Treatment of Patients with Diarrhea-As-
 sociated Irritable Bowel Syndrome (December 22, 2005);
 J.A. 7047–55.
      2   M. Pimentel et al., The Effect of a Nonabsorbed
 Oral Antibiotic (Rifaximin) on the Symptoms of the Irrita-
 ble Bowel Syndrome, 145 ANN. INTERN. MED., 557 (2006);
 J.A. 4639–46.
      3   Salix did not argue a difference between a motiva-
 tion to use rifaximin to treat IBS versus IBS-D. Decision
 at *19 n.3. It concedes on appeal that “[r]oughly one-third
 of IBS patients suffer from IBS-D,” Appellants’ Br. at 6,
 and has not otherwise suggested that treatments for IBS
 would not inform treatments of IBS-D.
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 *17–22. Salix appeals, asserting that the court erred in
 finding that a skilled artisan would have had a reasonable
 expectation of success in using the claimed 1,650 mg/day
 dosage to treat IBS-D. Appellants’ Br. at 39–48. Whether
 or not there would have been a reasonable expectation of
 success is a question of fact, IXI IP, LLC v. Samsung Elecs.
 Co., 903 F.3d 1257, 1262 (Fed. Cir. 2018), which we review
 for clear error, Hospira, 946 F.3d at 1328.
     Salix does not appear to dispute the district court’s
 finding that the Protocol and Pimentel “disclose all limita-
 tions of the IBS-D claims.” See Decision at *17. Rather, it
 contends that even if the asserted combination of refer-
 ences effectively discloses the claimed 1,650 mg/day dos-
 age, there remains insufficient evidence to support a
 finding of a reasonable expectation of success in using that
 particular dosage amount. See, e.g., Appellants’ Br. at 39–
 40. According to Salix, the highest prior art dosage amount
 that could have been supported with a reasonable expecta-
 tion of success was the 1,200 mg/day dose evaluated by Pi-
 mentel. Id. at 40. We disagree.
     The Protocol provides an outline of a planned Phase II
 clinical trial in which “three different doses (275, 550 and
 1100 mg) of rifaximin” were to be “administered BID [i.e.,
 twice-daily] for either two or four weeks in the treatment
 of patients with diarrhea-associated irritable bowel syn-
 drome.” J.A. 7050 (cleaned up). As an outline of that clin-
 ical trial plan, the Protocol provides only that those three
 specific, twice-daily dosage regimens were to be investi-
 gated for either two or four weeks. The Protocol does not
 include any efficacy or safety data, nor does it mention a
 1,650 mg/day dose or TID dosing.
     Although we have rejected the idea that “efficacy data
 [are] always required for a reasonable expectation of suc-
 cess,” OSI Pharms., LLC v. Apotex Inc., 939 F.3d 1375,
 1385 (Fed. Cir. 2019), we are hesitant to conclude as a gen-
 eral matter that the disclosure of a Phase II clinical trial
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 plan, standing alone, provides an expectation of success
 sufficient to render obvious a dosage that was not included
 within the planned clinical trial. See Appellants’ Reply Br.
 at 13−14. But the Protocol was not asserted alone; it was
 asserted in combination with Pimentel.
      Pimentel teaches that administration of 400 mg rifaxi-
 min, TID (1,200 mg/day), “resulted in greater improvement
 in IBS symptoms” and “lower bloating score[s] after treat-
 ment.” J.A. 4639; see also id. at 4642–43 (providing sup-
 porting data). Pimentel explains that the 400 mg TID
 regimen was chosen “on the basis of a previous study that
 demonstrated the efficacy of rifaximin in bacterial over-
 growth.” Id. at 4640. However, Pimentel does not merely
 provide that daily rifaximin doses of 1,200 mg were likely
 to be successful in the treatment of IBS. Pimentel further
 teaches that “[r]ecent data suggest that the optimal dosage
 of rifaximin may, in fact, be higher than that used in our
 study.” J.A. 4644; Decision at *20 (emphases added).
     The district court did not clearly err in finding that a
 skilled artisan would have looked to both of those refer-
 ences, considered their limits, and had a reasonable expec-
 tation of success as to the efficacy of 550 mg TID dosing.
 The combined message that the skilled artisan would have
 discerned from the Protocol and Pimentel is that the opti-
 mal dosage for treating patients suffering from IBS disor-
 ders may be higher than 400 mg TID, and the next higher
 dosage unit from the Protocol was 550 mg. We see no clear
 error in the conclusion that there would have been a rea-
 sonable expectation of success in administering the
 claimed 1,650 mg/day to IBS-D patients. Indeed, certainty
 and absolute predictability are not required to establish a
 reasonable expectation of success. See Almirall, LLC v.
 Amneal Pharms. LLC, 28 F.4th 265, 275 (Fed. Cir. 2022)
 (“A finding of a reasonable expectation of success does not
 require absolute predictability of success.”); Acorda Thera-
 peutics, Inc. v. Roxane Lab’ys, Inc., 903 F.3d 1310, 1333
 (Fed. Cir. 2018) (“This court has long rejected a
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 requirement of conclusive proof of efficacy for obviousness.”
 (cleaned up)).
      Moreover, references establishing the background
 knowledge of a person of ordinary skill in the art are con-
 sistent with the reasonable expectation of success provided
 by the combination of the Protocol with Pimentel. For ex-
 ample, Cuoco 4 teaches the efficacy of 1,200 mg rifaxi-
 min/day for 14 days for the treatment of small intestinal
 bacterial overgrowth (“SIBO”). J.A. 4533. Salix has
 acknowledged that those of ordinary skill in the art identi-
 fied “bacterial alterations” as a potential underlying cause
 for IBS, Appellants’ Br. at 7, and the literature 5 describes
 SIBO as a condition that is “highly prevalent in patients
 with irritable bowel syndrome (IBS),” such that “SIBO de-
 contamination is associated [with] a significant improve-
 ment of IBS symptoms.” J.A. 4664. We therefore agree
 with the district court that references describing the treat-
 ment of SIBO would have been pertinent to the skilled ar-
 tisan’s considerations as to what treatments would have a
 potential for success in treating individuals suffering from
 IBS.
     In addition to Cuoco, Lauritano6 teaches an increase in
 rifaximin efficacy for the treatment of SIBO as doses were
 increased from 600 mg/day to 1,200 mg/day, providing the

     4    L. Cuoco & M. Salvagnini, Small intestine bacterial
 overgrowth in irritable bowel syndrome: a retrospective
 study with rifaximin, 52 MINERVA GASTROENTEROL.
 DIETOL. (2006) 89; J.A. 4533–39.
     5    E. Scarpellini et al., High dosage rifaximin for the
 treatment of small intestinal bacterial overgrowth,
 25 ALIMENT. PHARMACOL. THER. 781 (2007); J.A. 4663−67
 (“Scarpellini”).
     6    E.C. Lauritano et al., Rifaximin dose-finding study
 for the treatment of small intestinal bacterial overgrowth,
 22 ALIMENT. PHARMACOL. THER., 31 (2005); J.A. 7267−71.
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 trend that Pimentel described as indicating that doses
 higher than 1,200 mg/day may be even more optimal for
 the treatment of IBS. J.A. 7267 (“Higher doses of rifaximin
 lead to a significant gain in terms of therapeutic efficacy in
 [SIBO] eradication without increasing the incidence of
 side-effects.”); see also id. at 4644. As evidenced by Scar-
 pellini and Lin, 7 those in the art advanced on those find-
 ings, and subsequently evaluated higher doses. For
 example, Scarpellini reported that a 1,600 mg/day dose
 “showed a significantly higher efficacy” compared with
 1,200 mg/day for the treatment of SIBO. J.A. 4663; see also
 id. at 4666 (Table 1, noting study patients included those
 suffering from IBS-D); id. at 4747 (teaching that “[a]bout
 400 to about 600 mg of rifaximin may be administered TID
 for about 10 days” (i.e., 1,200 mg/day to 1,800 mg/day) for
 the eradication of bacterial overgrowth).
     The record further supports the finding that there
 would have been a reasonable expectation of success in ad-
 ministering higher doses of rifaximin without an intolera-
 ble increase in negative side effects. For example, Cuoco
 teaches that rifaximin was understood as having “a low
 risk of causing microbial resistance,” J.A. 4533, and that
 rifaximin was well known for its “profile of tolerability and
 safety widely described in the literature,” id. at 4538. Scar-
 pellini further reported that the 1,600 mg/day dose pro-
 vided a “similar compliance and side-effect profile”
 compared with the 1,200 mg/day dose. Id. at 4663. As the
 district court noted, the “[w]idespread off-label use” of
 rifaximin also supported the conclusion that rifaximin was
 safe and effective “for the treatment of IBS-D with a rea-
 sonable expectation of success.” Decision at *19; see also
 Appellants’ Br. at 17 (“There is no dispute that skilled

      7 International Patent       Application    Publication
 2006/102536; J.A. 4721–47.
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 artisans knew of the general concept of trying off-label use
 of rifaximin to treat IBS-D.”).
     In view of the record before us, we see no clear error in
 the finding that a skilled artisan would have had a reason-
 able expectation of success in administering the claimed
 1,650 mg/day regimen for the treatment of IBS-D. We
 therefore affirm the district court’s holding that the chal-
 lenged IBS-D claims would have been obvious over the
 cited references. See In re Applied Materials, Inc., 692 F.3d
 1289, 1295 (Fed. Cir. 2012) (“[W]here the general condi-
 tions of a claim are disclosed in the prior art, it is not in-
 ventive to discover the optimum or workable ranges by
 routine experimentation.” (citation omitted)).
      Salix further contends that a Press Release 8 issued by
 Salix in a filing with the Securities and Exchange Commis-
 sion less than a year before the patents’ priority date was
 not prior art because Norwich failed to establish that it was
 “by others” as required by pre-AIA 35 U.S.C. § 102(a). Ap-
 pellants’ Br. at 30−39. According to Salix, the district
 court’s inclusion of that allegedly non-prior art reference in
 its discussion of the skilled artisan’s expectation of success
 was harmful error. Id.
     Although the district court cited the Press Release in
 its discussion of the skilled artisan’s expectations, it ulti-
 mately held that the “Protocol and Pimentel [] disclose all
 limitations of the IBS-D claims” and that a skilled artisan
 “would have been motivated to combine the . . . Protocol
 and Pimentel [] with a reasonable expectation of success.”
 Decision at *17. We therefore need not decide whether or
 not the Press Release was prior art because, even assuming
 that it was not, the Protocol and Pimentel alone estab-
 lished the obviousness of the claims.

     8   Salix Pharms., Ltd., Current Report (Form 8-K)
 (Sept. 5, 2007); J.A. 7477–82.
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     We accordingly affirm the district court’s determina-
 tion that Norwich established that the IBS-D claims would
 have been obvious in view of the Protocol and Pimentel.
                                II
     We next turn to Salix’s contention that the district
 court clearly erred in finding that there would have been a
 reasonable expectation of success in obtaining the rifaxi-
 min form β recited in the polymorph patents’ claims.
     Whether or not there would have been a reasonable ex-
 pectation of success is a question of fact, IXI IP, LLC v.
 Samsung Elecs. Co., 903 F.3d 1257, 1262 (Fed. Cir. 2018),
 which we review for clear error, Hospira, 946 F.3d at 1328.
 We review the ultimate conclusion of obviousness de novo.
 Id.
     The polymorph patents are directed to rifaximin form
 β. For example, claim 4 of the ’199 patent recites:
      4. Rifaximin in polymorphic form β, wherein the
      rifaximin has x-ray powder diffraction pattern
      peaks at about 5.4°; 9.0°; and 20.9°2θ and wherein
      the rifaximin has a water content of greater than
      5%.
 ’199 patent, col. 10 ll. 24–27; see also ’206 patent, col. 11 ll.
 33–37, 41–43 (claims 34 & 36, similar).
     Norwich challenged the polymorph claims’ validity by
 asserting, inter alia, Cannata, 9 which discloses that rifaxi-
 min exists in crystalline form with “outstanding antibacte-
 rial properties.” J.A. 4528; Decision at *6. Cannata does
 not discuss rifaximin’s crystal structure in detail, but it
 does disclose several preparation protocols for rifaximin
 that include solvents used for crystallization. J.A. 4529–
 31; see also id. at 3408.

      9   U.S. Patent 4,557,866; J.A. 4526−32.
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      The district court held that expert testimony supported
 a conclusion that, in view of the prior art, (1) a skilled arti-
 san would have had good reason to characterize the crys-
 talline rifaximin obtained by following the Cannata
 protocols, (2) that such characterization was routine and
 could have been performed “in one day,” and (3) that doing
 so would have led the skilled artisan to have “detected
 rifaximin β.” Decision at *6–7. The district court subse-
 quently concluded that the challenged polymorph claims
 would have been obvious over the asserted prior art in view
 of the common knowledge of the skilled artisan. Id. at *7–
 8.
     Salix first challenges the district court’s conclusion of
 obviousness by asserting that Grunenthal GMBH v. Alkem
 Laboratories Ltd., 919 F.3d 1333 (Fed. Cir. 2019) and Phar-
 macyclics LLC v. Alvogen, Inc., No. 2021-2270, 2022 WL
 16943006 (Fed. Cir. Nov. 15, 2022) compel the opposite re-
 sult. Appellants’ Br. at 49–51. Salix further contends that
 the court “applied the wrong test” by not following a ra-
 tionale provided in the district court opinion from Pharma-
 cyclics. Id. at 55–57. We disagree.
      In Grunenthal, we held that it was not clear error for
 the district court to find that the record failed to establish
 by clear and convincing evidence a reasonable expectation
 of success in preparing the claimed polymorphic Form A of
 tapentadol hydrochloride. See 919 F.3d at 1341. In that
 case, the synthesis of tapentadol hydrochloride known in
 the prior art produced a particular form—Form B. Id. The
 district court found that there was a lack of evidence that
 a prior art synthesis would have resulted in the claimed
 Form A and that no prior art guidance existed to establish
 “what particular solvents, temperatures, agitation rates,
 etc., were likely to result” in the claimed polymorph. Id. at
 1343. We found no clear error in that analysis. Id. at
 1344–45.
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     We also affirmed a conclusion of non-obviousness of a
 claimed polymorph in our non-precedential Pharmacyclics
 decision, which issued after the district court released its
 decision in this case. See 2022 WL 16943006, at *10–11.
 But the court here acted within its discretion when it de-
 clined to follow the district court decision in Pharmacyclics
 as though it was binding precedent. See Decision at *7 n.1
 (“Plaintiffs call to my attention [the district court’s decision
 in] Pharmacyclics LLC v. Alvogen Pine Brook LLC. I have
 considered that case but I do not agree with it on this
 point.”). And our later affirmance of the factual findings in
 Pharmacyclics did not retroactively override the district
 court’s analysis here.
      Moreover, a lack of clear error in Grunenthal and Phar-
 macyclics does not compel a conclusion of non-obviousness
 here. Indeed, Grunenthal underscored the factual nature
 of these types of inquiries and expressly held that it did
 “not rule out the possibility that polymorph patents could
 be found obvious.” 919 F.3d at 1344–45. “The determina-
 tion of obviousness is dependent on the facts of each case.”
 Sanofi-Synthelabo v. Apotex, Inc., 550 F.3d 1075, 1089
 (Fed. Cir. 2008); see also Pfizer, Inc. v. Apotex, Inc.,
 480 F.3d 1348, 1366 (Fed. Cir. 2007). In Grunenthal and
 Pharmacyclics, the issue was whether a skilled artisan
 would have had a reasonable expectation of success in pro-
 ducing a crystalline form of a compound. See 919 F.3d at
 1341–43; 2022 WL 16943006, at *10–11. Here, the prior
 art included a process to produce a crystalline form of rifax-
 imin, and the dispute centered around characterizing the
 crystalline form resulting from that process. See Decision
 at *13–14. These distinct factual predicates support the
 district courts’ factual findings in each of these three cases
 under the clear error standard of review.
     In Graham v. John Deere Co. of Kansas City, 383 U.S.
 1 (1966), the Supreme Court set forth the background
 against which obviousness is to be assessed: “Under § 103,
 the scope and content of the prior art are to be determined”
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 and “differences between the prior art and the claims at
 issue are to be ascertained.” Id. at 17. The scope and con-
 tent of the prior art here includes preparations of crystal-
 line rifaximin, which expert testimony supports would
 have yielded the β form of rifaximin. Decision at *7; J.A.
 3391−92 (“[T]he as-synthesized form of rifaximin reported
 by Examples 1, 6, 7, and 9 [of Cannata] were necessarily
 rifaximin form Beta, because of the methods used, the sol-
 vent system used, and it was later confirmed by later work,
 including work from the named inventors.”); id. at 3408−09
 (similar testimony); id. at 3393−3404 (discussing the evi-
 dence of record that supports that conclusion); id. at
 4700−07, 4846−47, 5007−14 (providing supporting evidence
 for that conclusion). And the parties do not dispute that
 the methods for characterizing the resulting crystalline
 rifaximin were well known and readily available to the
 skilled artisan. Decision at *3. The difference between the
 prior art and the claims is thus effectively nothing more
 than the performance of routine characterization to iden-
 tify the polymorphic forms that result from the known Can-
 nata processes.
      In this regard, Salix does not appear to dispute that
 there would have been a motivation to explore potential
 polymorphic forms of rifaximin. Appellants’ Br. at 48–49.
 Rifaximin was, after all, a known compound with a known,
 useful activity. Salix further refers to the district court’s
 finding that “polymorph β is a commonly produced poly-
 morph and the most stable form of rifaximin” as an “undis-
 puted” fact. Id.; see also Decision at *7. There thus appears
 to be no dispute that the claimed polymorph can be readily
 produced from the crystallization conditions disclosed in
 Cannata and that it would have been well within the abil-
 ities of the skilled artisan to procure and characterize the
 β form of rifaximin.
     According to Salix, however, rifaximin’s β form consti-
 tuted a non-obvious invention because, although skilled ar-
 tisans “actually succeed[ed]” in producing and
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 characterizing it, they would not have “expect[ed] to suc-
 ceed” because, as of the critical date, the polymorphic na-
 ture of rifaximin had not yet been reported and the identity
 of the β form remained undisclosed. Appellants’ Br. at 49.
 Salix further argues that there could have been no expec-
 tation of success because the skilled artisan would not have
 been able to predict what polymorphic forms might result
 from following the preparation protocols disclosed in the
 prior art. Id. at 20−21, 50−53. Salix’s framing of the issue
 suggests that no unknown entity could ever be obvious, as
 one cannot reasonably expect what was hitherto unknown,
 which is incorrect.
     Here, the district court found a reasonable expectation
 of success in characterizing the crystalline product of Can-
 nata for potential polymorphism using routine, conven-
 tional methods and skill. Decision at *6–7. We see no clear
 error in that conclusion. Indeed, Salix has done no more
 than combine known elements of the prior art to verify
 readily accessible information concerning a compound al-
 ready in the hands of those of ordinary skill in the art, and
 such routine efforts do not justify removing this polymorph
 from the public domain. See KSR Int’l Co. v. Teleflex Inc.,
 550 U.S. 398, 427 (2007); see also Pfizer, 480 F.3d at
 1367−68. To be sure, we do not hold that there is always a
 reasonable expectation of success in accessing or character-
 izing polymorphs. We are simply reviewing the district
 court’s decision before us as to its factual finding of a rea-
 sonable expectation of success, and in so doing, have not
 been left with a definite and firm conviction that a mistake
 was made in reaching that finding. See Scanner Techs.
 Corp. v. ICOS Vision Sys. Corp. N.V., 528 F.3d 1365, 1374
 (Fed. Cir. 2008).
      Having found no clear error in the district court’s fact
 findings as to the existence of a reasonable expectation of
 success, we affirm the court’s conclusion that the poly-
 morph patent claims were invalid as obvious. Because we
 affirm the court’s holding that the polymorph patent claims
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 would have been obvious over the asserted prior art, we
 need not consider Norwich’s separate argument that the
 polymorph claims would have also been invalid as inher-
 ently anticipated.
                              III
      On cross-appeal, Norwich raises two related but dis-
 tinct arguments that arose after the district court held that
 Norwich infringed the HE patents and failed to establish
 invalidity. See Decision at *10−16. Norwich first argues
 that, in issuing its final decision, the district court misin-
 terpreted 35 U.S.C. § 271(e)(4)(A), which directs a court,
 following a finding of infringement, to order the FDA to de-
 fer final approval of an ANDA until the expiration of the
 infringed patent. According to Norwich, that statute pre-
 cludes delaying final approval of an entire ANDA, and in-
 stead requires delaying only the approval of the infringing
 use.
     Norwich’s second argument arises from its decision to
 amend its ANDA to carve out the infringing HE use after
 final judgment. Following that amendment, Norwich filed
 a motion to modify the final judgment to allow for prompt
 approval of the amended ANDA that purportedly no longer
 sought approval for the infringing HE use. The district
 court denied that motion, and Norwich cross-appealed.
     We address both of Norwich’s concerns in turn.
                              A.
     We first address Norwich’s arguments regarding the
 district court’s interpretation of 35 U.S.C. § 271(e)(4)(A) in
 ordering that a final approval of Norwich’s ANDA could not
 be effective before the HE patents expired. J.A. 50−51.
     We review issues of statutory interpretation without
 deference to the district court’s interpretation. Waymark
 Corp. v. Porta Sys. Corp., 245 F.3d 1364, 1366 (Fed. Cir.
 2001).   “The starting point in every case involving
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                              NORWICH PHARMACEUTICALS INC.

 construction of a statute is the language itself.” Blue Chip
 Stamps v. Manor Drug Stores, 421 U.S. 723, 756 (1975)
 (Powell, J., concurring). Moreover, we “give effect, if possi-
 ble, to every clause and word of [the] statute.” United
 States v. Menasche, 348 U.S. 528, 538–39 (1955) (citation
 omitted). When a statute does not define a given word or
 phrase, we presume that Congress intended the word or
 phrase to have its ordinary meaning. Asgrow Seed Co. v.
 Winterboer, 513 U.S. 179, 187 (1995). However, “[i]n ex-
 pounding a statute, we must not be guided by a single sen-
 tence or member of a sentence, but look to the provisions of
 the whole law, and to its object and policy.” U.S. Nat’l Bank
 of Or. v. Indep. Ins. Agents of Am., Inc., 508 U.S. 439, 455
 (1993) (citation omitted).
      Section 271(e)(4)(A) instructs that, following a finding
 of infringement, “the court shall order the effective date of
 any approval of the drug or veterinary biological product
 involved in the infringement to be a date which is not ear-
 lier than the date of the expiration of the patent which has
 been infringed.” The order here instructed the FDA that
 “the effective date of any final approval . . . of Norwich’s
 ANDA No. 214369 is to be a date not earlier than the date
 of expiration of the last to expire of [the HE patents] (cur-
 rently October 2, 2029).” J.A. 51.
     Norwich argues that the language of § 271(e)(4) re-
 quires courts to tie the restriction on FDA approval to the
 indication for which the ANDA seeks approval when that
 indication was the source of infringement. Cross-Appel-
 lants’ Br. at 14. Norwich’s ANDA originally sought ap-
 proval for the treatment of both IBS-D and HE. Although
 only the HE indication was found to infringe a valid patent,
 the order restricted final approval of the entire ANDA, in-
 cluding the non-infringing indication, until 2029. Norwich
 argues that the statute requires the district court’s order
 “to specify that the approval date pertains to Norwich’s
 ANDA seeking approval for the infringing HE Indication.”
 Id. at 18. But the district court order concerned only the
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 NORWICH PHARMACEUTICALS INC.

 specific ANDA in question that included an infringing use,
 referred to the ANDA by its number, and enjoined the ap-
 proval of that ANDA. J.A. 51. Norwich suggests that the
 district court order unfairly precludes it from receiving fi-
 nal approval of a new non-infringing ANDA. 10 The district
 court did no such thing.
     Section 271(e)(4)(A) describes delaying the approval of
 “the drug . . . involved in the infringement.” Since the FDA
 does not approve drugs in the abstract, but rather approves
 drugs for particular uses (indications) of that drug, the
 statute is appropriately construed as directed to approval
 of particular infringing uses of the drug, not all uses of the
 drug including non-infringing uses. The statutory scheme
 makes clear that it is not the potential use of Norwich’s
 rifaximin for HE that constitutes the relevant infringe-
 ment here, nor is it the unpatented drug compound itself,
 but rather it is the submission of the ANDA that included
 an infringing use. See 35 U.S.C. § 271(e)(2)(A) (making it
 an “act of infringement to submit” an ANDA “for a drug
 claimed in a patent or the use of which is claimed in a pa-
 tent”). That the ANDA further recited a non-patent-pro-
 tected indication does not negate the infringement
 resulting from the ANDA’s submission. The order thus ap-
 propriately delayed the effective final approval date of “this
 infringing ANDA” submission. J.A. 48. The order appro-
 priately said nothing that would prevent approval of a new
 non-infringing ANDA.
     We therefore affirm the district court’s order setting
 the effective approval date of Norwich’s ANDA No. 214369

     10  Norwich notes that on June 2, 2023, FDA tenta-
 tively approved its amended ANDA, which purportedly
 lacks the HE indication. Cross-Appellant’s Br. at 6. The
 tentative approval letter noted, however, that “final ap-
 proval cannot be granted until October 2, 2029 as specified
 in the court order.” Id.
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                               NORWICH PHARMACEUTICALS INC.

 to be no earlier than the date of expiration of the last to
 expire of the HE patents.
                               B.
      Following entry of the final judgment, which included
 the resetting order barring final approval of Norwich’s
 ANDA until 2029, Norwich amended its ANDA in an at-
 tempt to remove the infringing HE indication. Norwich
 then moved to modify the judgment under Federal Rule of
 Civil Procedure 60(b), asserting that the amendment ne-
 gated any possible infringement, and that the final ap-
 proval date of the ANDA, as amended, should not be tied
 to the HE patents. See Cross-Appellant’s Br. at 27. The
 district court denied that motion, holding that Norwich
 “fully litigated the merits of its non-infringement and inva-
 lidity case, lost, and now seeks a way around the final judg-
 ment through Rule 60(b).” Rule 60(b) Order at *2. Norwich
 cross-appealed.
     “Because denial of a Rule 60(b) motion is a procedural
 issue not unique to patent law, we apply the rule of the re-
 gional circuit where appeals from the district court would
 normally lie,” Amstar Corp. v. Envirotech Corp., 823 F.2d
 1538, 1550 (Fed. Cir. 1987), which, here, is the Third Cir-
 cuit. The Third Circuit “review[s] the denial of Rule 60(b)
 relief for an abuse of discretion.” Coltec Indus., Inc. v. Hob-
 good, 280 F.3d 262, 269 (3d Cir. 2002); see also Bohus v.
 Beloff, 950 F.2d 919, 930 (3d Cir. 1991) (noting that Rule
 60(b) motions are “extraordinary relief which should be
 granted only where extraordinary justifying circumstances
 are present” (citation omitted)).
     “A district court may reconsider its own finding of in-
 fringement in light of an amended ANDA,” but the court
 need not do so. Ferring B.V. v. Watson Lab’ys, Inc. Fla.,
 764 F.3d 1382, 1391 (Fed. Cir. 2014). Rather, “[a]llowing
 an amendment is within the discretion of the district court,
 guided by principles of fairness and prejudice to the patent-
 holder.” Id. Here, the court reasonably held that
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 NORWICH PHARMACEUTICALS INC.

 consideration of the amended ANDA would be inequitable
 and inappropriate. Rule 60(b) Order at *2. The court noted
 that “[i]t is not a simple matter to determine whether an
 ANDA applicant has successfully carved out language from
 a label to turn infringement into non-infringement” and
 that what Norwich sought in its Rule 60(b) motion “would
 essentially be a second litigation” following final judgment.
 Id. (noting also that, other than simply asserting that it
 carved out the HE indication and providing the court with
 the amended label, Norwich “ha[d] presented no evidence
 in support of its assertion” that the amended ANDA would
 no longer infringe the HE patents).
     Norwich nevertheless argues that the amended ANDA
 satisfies the judgment by not seeking approval for the in-
 fringing use and that, in view of the amendment, it is no
 longer equitable to apply the judgment prospectively. But
 Rule 60(b) is permissive, holding only that the court “may
 relieve a party or its legal representative from a final judg-
 ment, order, or proceeding” under various circumstances.
 That is—a district court has the discretion, not the obliga-
 tion, to modify a final judgment in view of a post-judgment
 ANDA amendment. And as the district court held, simply
 asserting that a patented indication has been carved out of
 an ANDA application does not necessarily satisfy the judg-
 ment or entitle the applicant to direct entry to the market.
 See Rule 60(b) Order at *2. We see no abuse of discretion
 in the district court reaching that conclusion or in subse-
 quently denying the motion.
      Norwich further argues that the district court erred by
 not explicitly discussing Rule 60(b)(6), which provides that
 a court may relieve a party from a final judgment for “any
 other reason that justifies relief.” We disagree that the dis-
 trict court so erred. The court’s Memorandum Order thor-
 oughly discussed the law, the equities, the record, and the
 arguments before it. In so doing, the court implicitly found
 no additional reason that justified the relief that Norwich
 sought.
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                               NORWICH PHARMACEUTICALS INC.

    We therefore affirm the district court’s denial of the
 motion to modify the final judgment.
                          CONCLUSION
     We have considered both parties remaining arguments
 and find them unpersuasive. For the foregoing reasons, we
 affirm (1) the district court’s holding that claim 2 of the ’569
 patent, claim 3 of the ’667 patent, claim 4 of the ’199 patent,
 and claim 36 of the ’206 patent would have been invalid as
 obvious, (2) the district court’s order setting the effective
 approval date of Norwich’s ANDA to be no earlier than the
 date of expiration of the last to expire of the HE patents,
 and (3) the district court’s denial of the motion to modify
 the final judgment.
                         AFFIRMED
                             COSTS

 No costs.
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    United States Court of Appeals
        for the Federal Circuit
                   ______________________

      SALIX PHARMACEUTICALS, LTD., SALIX
    PHARMACEUTICALS, INC., BAUSCH HEALTH
        IRELAND LTD., ALFASIGMA S.P.A.,
               Plaintiffs-Appellants

                              v.

        NORWICH PHARMACEUTICALS INC.,
             Defendant-Cross-Appellant
              ______________________

                    2022-2153, 2023-1952
                   ______________________

     Appeals from the United States District Court for the
 District of Delaware in No. 1:20-cv-00430-RGA, Judge
 Richard G. Andrews.
                 ______________________
 CUNNINGHAM, Circuit Judge, dissenting in part.
      I join most of the majority’s opinion, but I respectfully
 dissent from the majority’s opinion concerning U.S. Patent
 Nos. 8,309,569 and 10,765,667 (the “IBS-D patents”). I
 would vacate the district court’s judgment that the as-
 serted claims of the IBS-D patents are obvious and remand
 for further proceedings.
                               I
     The district court found that “[t]he asserted IBS-D
 claims describe a dosing regimen within the known range”
 and that “[a] POSA would have been motivated to combine
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 2                            SALIX PHARMACEUTICALS, LTD. v.
                              NORWICH PHARMACEUTICALS INC.

 the RFIB 2001 Protocol 1 and Pimentel 2006 2 with a rea-
 sonable expectation of success.” Salix Pharms., Ltd. v. Nor-
 wich Pharms., Inc., No. 20-430-RGA, 2022 WL 3225381, at
 *17 (D. Del. Aug. 10, 2022) (“Decision”) (footnotes added).
 Based on these findings of fact, the court concluded that
 “Pimentel 2006 in light of the RFIB 2001 Protocol renders
 the asserted claims of the IBS-D patents obvious.” Id. at
 *18. After reviewing the evidence relied on by the district
 court, applying a clear error standard, I am “left with the
 definite and firm conviction that a mistake has been com-
 mitted” regarding these findings. Pfizer, Inc. v. Apotex,
 Inc., 480 F.3d 1348, 1359 (Fed. Cir. 2007) (quoting United
 States v. U.S. Gypsum Co., 333 U.S. 364, 395 (1948)).
     The evidence cited by the district court does not sup-
 port its finding that a skilled artisan would have a reason-
 able expectation of success for the claimed dosage. See
 Decision at *17, *19. “The reasonable-expectation-of-suc-
 cess analysis must be tied to the scope of the claimed in-
 vention”––here, the claimed 1,650 mg/day (550 mg TID 3)
 dosage for treating IBS-D. Teva Pharms. USA, Inc. v. Cor-
 cept Therapeutics, Inc., 18 F.4th 1377, 1381 (Fed. Cir.
 2021). The district court mainly relied on the results of the

     1    ClinicalTrials.gov, History of Changes for Study:
 NCT00269412, Randomized, Double Blind, Placebo-Con-
 trolled Study to Assess the Efficacy and Safety of Three Dif-
 ferent Doses of Rifaximin Administered BID Either Two or
 Four Weeks in the Treatment of Patients with Diarrhea-As-
 sociated Irritable Bowel Syndrome (December 22, 2005);
 J.A. 7048–55.
      2   M. Pimentel et al., The Effect of a Nonabsorbed
 Oral Antibiotic (Rifaximin) on the Symptoms of the Irrita-
 ble Bowel Syndrome, 145 ANNALS INTERN. MED. 557 (2006);
 J.A. 4639–46. The majority refers to this reference as Pi-
 mentel.
      3   TID stands for three times per day.
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 NORWICH PHARMACEUTICALS INC.

 RFIB 2001 trial disclosed in the RFIB 2001 Press Release 4
 in arriving at this conclusion. Decision at *19. However,
 there is no reason that a skilled artisan “would have known
 about the successful RFIB 2001 Protocol results,” id., as to
 the claimed 1,650 mg/day (550 mg TID) dosage because the
 RFIB 2001 Press Release only discloses an improvement in
 the 550 mg twice-a-day group. J.A. 7480; see Decision at
 *19. In fact, evidence in the record suggests the opposite—
 that a skilled artisan might have understood the absence
 of discussions of the 1,100 mg twice-a-day group to imply
 that higher dosage did not lead to similar successful re-
 sults. See J.A. 3313–14. Indeed, the 2,200 mg/day dosage
 “did not achieve more responders compared to the placebo
 for adequate relief.” 5 J.A. 3042. Thus, the court’s reliance
 on the RFIB 2001 Press Release to establish a reasonable
 expectation of success was erroneous. 6
     The district court’s citations to other references do not
 cure this error. Cuoco 7 discloses a total dose of 1,200

     4   Salix Pharms., Ltd., Current Report (Form 8-K)
 (Sept. 5, 2007); J.A. 7477–82.
     5   Although the evidence that the 2,200 mg/day dos-
 age did not achieve adequate relief post-dates the priority
 date of the patent, it clarifies what a skilled artisan would
 have understood from the RFIB 2001 Press Release. See
 Syntex (U.S.A.) LLC v. Apotex, Inc., 407 F.3d 1371, 1379
 (Fed. Cir. 2005) (holding district court erred in not consid-
 ering a reference that post-dates the priority date when it
 is relevant to what “was known in the art at the relevant
 time”).
     6   Salix also challenges the district court’s finding
 that the RFIB 2001 Press Release was prior art. Appel-
 lant’s Br. 30–39; Decision at *20. I agree with the majority
 that we do not need to reach this issue.
     7   L. Cuoco & M. Salvagnini, Small intestine bacterial
 overgrowth in irritable bowel syndrome: a retrospective
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 4                            SALIX PHARMACEUTICALS, LTD. v.
                              NORWICH PHARMACEUTICALS INC.

 mg/day for 14 days, and Barrett 8 similarly discloses 400
 mg TID for a total dosage of 1,200 mg/day. Decision at
 *19; see also J.A. 4536; J.A. 4800. The district court did not
 explain why these references would give rise to a reasona-
 ble expectation of success for a dosage that is almost 40%
 higher.     The reference by the district court to the
 “[w]idespread off-label use” of rifaximin was also unaccom-
 panied by any discussion of dosages or citations to the rec-
 ord. Decision at *19. Likewise, it discussed market
 research that shows many physicians prescribe rifaximin
 for IBS without discussing their prescribed dosages. Deci-
 sion at *20 (citing J.A. 7186). The cited research does not
 show that physicians prescribe at the 1,650 mg/day (550
 mg/TID) dosage. J.A. 7186.
     Although “efficacy data is [not] always required for a
 reasonable expectation of success,” OSI Pharms., LLC v.
 Apotex Inc., 939 F.3d 1375, 1385 (Fed. Cir. 2019), the anal-
 ysis must still be tied to the scope of the claims—here, the
 1,650 mg/day dosage. See Teva, 18 F.4th at 1381; see also
 In re Cyclobenzaprine Hydrochloride Extended-Release
 Capsule Pat. Litig., 676 F.3d 1063, 1070–72 (Fed. Cir.
 2012) (finding no reasonable expectation of success when
 the court “cited no evidence specifically indicating that a
 [drug with a pK profile disclosed in the prior art] would be
 expected to yield the same therapeutic effect as [a different
 pK profile as claimed]”); Ferring B.V. v. Watson Lab’ys,
 Inc.-Fla., 764 F.3d 1401, 1407 (Fed. Cir. 2014) (finding as-
 serted claims not to be invalid for obviousness when prior
 art references “disclose 500 mg [] formulations, but no

 study with rifaximin, 52 MINERVA GASTROENTEROL.
 DIETOL. 89 (2006); J.A. 4533–39.
     8   G. Barrett, Abstract, Benefits of the Antibiotic
 Rifaximin as Empiric Therapy in Patients with Irritable
 Bowel Syndrome, 101 AM. J. GASTROENTEROL. S479 (2006);
 J.A. 4799–4800.
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 NORWICH PHARMACEUTICALS INC.

 higher tablet strengths, and particularly not the claimed
 650 mg formulation”). Aside from its erroneous reliance on
 the RFIB 2001 Press Release, the district court failed to tie
 its reasonable expectation of success analysis to the
 claimed dosage. Therefore, I would find that it clearly
 erred in its reasonable expectation of success analysis.
     In sum, the district court clearly erred in relying on the
 RFIB 2001 Press Release and other references that do not
 teach the claimed dosage. For these reasons, I would have
 found the district court’s finding to be clearly erroneous
 and would vacate the district court’s judgment that the
 IBS-D claims were invalid as obvious.
                               II
      In affirming the district court’s judgment of obvious-
 ness, the majority relies on one additional sentence in Pi-
 mentel 2006 regarding the reasonable expectation of
 success analysis: “Recent data suggest that the optimal
 dosage of rifaximin may, in fact, be higher than that used
 in our study.” J.A. 4644; see Maj. Op. 8. But the lack of
 discussion of any actual dosage that may be optimal, the
 use of the word “may,” and the fact that the RFIB 2001
 Protocol discloses a specific dosing regimen of 2,200 mg/day
 rather than 1,650 mg/day all call into question the major-
 ity’s finding. Indeed, the district court only relied on this
 sentence in its motivation to combine analysis and did not
 rely on this sentence in its reasonable expectation of suc-
 cess analysis. See Decision at *18–20. The parties never
 made this argument before us. Therefore, I disagree that
 this additional sentence, when considered together with
 the RFIB 2001 Protocol, would give rise to a reasonable ex-
 pectation of success for the claimed dosage.
     The majority also discusses references not relied on by
 the district court in its reasonable expectation of success
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 6                            SALIX PHARMACEUTICALS, LTD. v.
                              NORWICH PHARMACEUTICALS INC.

 analysis, including Lauritano9, Scarpellini 10, and Lin. 11
 Maj. Op. 9–10. But the district court did not make any
 findings on what these references teach, other than finding
 that the references were prior art. See Decision at *17–22.
 Nor are the majority’s conclusions regarding these refer-
 ences uncontested. For example, Salix argues that Scar-
 pellini and Lauritano are both directed to the treatment of
 small intestinal bacterial overgrowth (SIBO), not to the
 treatment of IBS or IBS-D, and therefore cannot establish
 a reasonable expectation of success. Appellant’s Reply Br.
 18. Although the majority may be right that Lauritano’s
 and Scarpellini’s disclosures on treating SIBO also support
 finding a reasonable expectation of success for treating
 IBS-D, see Maj. Op. 9–10, the district court never made this
 finding. See Golden Bridge Tech., Inc. v. Nokia, Inc., 527
 F.3d 1318, 1323 (Fed. Cir. 2008) (declining to find what a
 prior art reference teaches in the first instance). It merely
 found that “[t]he relationship between IBS and SIBO was
 actively being explored,” and that certain prior art refer-
 ences “do not teach away from using rifaximin to treat
 IBS.” Decision at *21. I would not make such fact-findings
 about Scarpellini and Lauritano in the first instance.
     In summary, I would vacate the district court’s judg-
 ment that the asserted claims of the IBS-D patents were
 obvious and remand for further proceedings. On remand,
 I would order the district court to consider in the first in-
 stance the teachings in the additional prior art references.

     9    E.C. Lauritano et al., Rifaximin dose-finding study
 for the treatment of small intestinal bacterial overgrowth,
 22 ALIMENT. PHARMACOL. THER. 31 (2005); J.A. 7267−71.
     10   E. Scarpellini et al., High dosage rifaximin for the
 treatment of small intestinal bacterial overgrowth,
 25 ALIMENT. PHARMACOL. THER. 781 (2007); J.A. 4663−67.
     11   International Patent Application Publication No.
 WO 2006/102536; J.A. 4721–47.
Case: 22-2153    Document: 71     Page: 29   Filed: 04/11/2024

 SALIX PHARMACEUTICALS, LTD. v.                            7
 NORWICH PHARMACEUTICALS INC.

 See ACS Hosp. Sys., Inc. v. Montefiore Hosp., 732 F.2d
 1572, 1578 (Fed. Cir. 1984) (“Where the trial court fails to
 make findings, the judgment will normally be vacated and
 the action remanded for appropriate findings to be made.”).
 Accordingly, I respectfully dissent in part.