Full opinion text
OPINION AND ORDER LYNCH, District Judge. The Hatch-Waxman Act, 21 U.S.C. § 355 and 35 U.S.C. § 271(e) (1994) (codified as amended), permits would-be manufacturers of generic versions of an already approved, patented drug to seek expedited approval from the Food and Drug Administration (“FDA”) before expiration of the patent, by means of an Abbreviated New Drug Application (“ANDA”). See Yamanouchi Pharmaceutical Co., Ltd. v. Danbury Pharmacal, Inc., 231 F.3d 1339, 1342 (Fed.Cir.2000). Filing an ANDA constitutes an “artificial” but legally cognizable instance of patent infringement, often triggering a lawsuit in which the validity and enforceability of the patent may be tested. Glaxo Group Ltd. v. Apotex, Inc., 376 F.3d 1339, 1344 (Fed.Cir.2004). Dr. Reddy’s Laboratories, Ltd., and Dr. Reddy’s Laboratories, Inc. (collectively, “Reddy”), and Teva Pharmaceuticals USA, Inc. (“Teva”), the defendants in these actions, each filed an ANDA, seeking to manufacture generic versions of a gastric-acid inhibitor that is marketed under the brand name Aciphex. Plaintiffs Eisai Co., Ltd. and Eisai Inc. (collectively, “Eisai”), hold the patent on rabeprazole sodium, the active ingredient of Aciphex. Eisai duly brought these actions for patent infringement against defendants. Defendants argue that Eisai’s patent should not be enforced because Eisai engaged in inequitable conduct before the U.S. Patent and Trademark Office (“PTO”) during prosecution of its patent application. Ei-sai now moves for summary judgment on all defendants’ allegations of inequitable conduct. For the reasons below, the motion is granted in part, but for the most part denied. THE PATENT PROSECUTIONS To address the parties’ contentions requires reciting in some detail the history of the prosecutions of both the rabeprazole patent and another Eisai patent application that defendants argue is closely related. The following facts regarding those prosecutions are undisputed except as otherwise noted. Given the scope and somewhat specialized nature of the record, however, citations are provided to identify the source of certain facts. Where citations point to a statement in a party’s brief or other non-evidentiary submission, that statement is generally uncontested and usually itself points to evidentiary material in the record. 1. Prosecution of The Patent-in-Suit Eisai, a pharmaceutical company, owns U.S. Patent No. 5,045,552 (“ ’552 patent”), the patent-in-suit. The ’552 patent claims, among other things, the chemical compound rabeprazole and its salts. Ra-beprazole sodium is the active ingredient in a drug that Eisai developed and made commercially available under the brand name Aciphex. The drug was approved by the FDA in 1991 for treatment of certain gastric ailments including duodenal ulcers and heartburn. Rabeprazole functions as a “proton pump inhibitor,” because it suppresses gastric-acid production by inhibiting the action of an enzyme, H ' K ' ATPase, which pumps into the stomach protons (H+ ions) that combine with chloride ions to form hydrochloric (gastric) acid. (Ds. Joint R. 56.1 Stmt. ¶ 15.) The market for Aciphex is a lucrative one: Eisai’s worldwide sales of the drug have been reported at over $1 billion per year. (Ds. Joint R. 56.1 Stmt. ¶¶ 1-5.) On November 10, 1987, Eisai’s attorney Arthur R. Crawford filed the application that resulted in the ’552 patent. (’552 File History, DRLRAB 51.) The application reported that the compound now referred to as rabeprazole belonged to a known class whose chemical structures include a benzimidazole ring on the left side of the molecule as diagramed in the standard chemical notation, and a pyridine ring on the right, joined by a sulfinylmethyl group. (P.Ex. 1, ’552 patent, col. 1, lines 40-44.) Numerous compounds feature this basic chemical structure, including prominently omeprazole, the first commercially available proton pump inhibitor; omeprazole was disclosed in a group of patents (known as “Junggren” after an inventor) owned by the Swedish company now known as As-traZeneca AB. It is the active ingredient in the drug marketed as Prilosec. (Ds. Joint R. 56.1 Stmt ¶ 19; ’552 Patent File History, DRLRAB 54, 481; see also Teva Mem. in Opp. to P. Mot. for Summ. J. of Patent Validity, 1-2.) The compounds are formally distinguishable primarily by the particular “substitutions” of chemical groups for hydrogen atoms around their pyridine rings. The structure of rabeprazole’s pyridine ring reflects a pattern of substitution referred to in this litigation as “asymmetrical,” because its 3-position is substituted (with a methyl group) while the 5-position is unsubstituted (that is, it is bonded to a hydrogen atom); the 4-position is substituted with a methoxypropoxy group (OCH2 CH2CH2OCH3), a type of alkoxy group. (P. Mem., glossary at 7.) Other related compounds, some of which are potentially useful in the inhibition of gastric-acid formation, have different patterns of pyridine-ring substitution, including the use of different alkoxy groups at the 4-position. The benzimidazole ring of rabeprazole is unsubstituted. (Id.) Eisai reported having synthesized ra-beprazole by working from omeprazole. (P.R. 56.1 Stmt. ¶¶ 18, 24.) Eisai disclosed summaries of three sets of pharmacological data comparing, relevantly, omeprazole to rabeprazole. (Ds. Joint R. 56.1 Stmt. ¶ 37.) These disclosures will be further discussed in relation to defendants’ inequitable conduct claims, but, in brief, they purported to demonstrate rabeprazole’s superior potency and its enabling of faster post-dosage recovery of acid secretion as compared to omeprazole. (P.R. 56.1 Stmt. ¶¶ 19, 21, 23-27, 36-39 (citing ’552 patent)). The submitted data were not the only existing pharmacological comparisons involving rabeprazole, as will further be discussed in relation to the inequitable conduct claims. A. First Rejection and Eisai’s Response Patent examiner Jane Fan rejected the rabeprazole claims three times, prompting various persuasive efforts by Eisai, before ultimately allowing the claims to issue as the ’552 patent. On September 21, 1988, Fan rejected the claims as obvious in light of certain prior art: the Junggren patents and Great Britain Patent No. 2,234,523 (“GB ’523”). (Ds. Joint R. 56.1 Stmt. ¶¶ 41-42.) “[Junggren] and [GB ’523] generically teach[ ] R [the 4-position on the pyridine ring] being methoxyethoxy or ethoxyethoxy,” wrote Fan. (’552 File History at DRLRAB 292.) Fan specifically cited and diagramed a prior art-compound, Example 27 of Junggren, which bears a methoxyethoxy substituent at the 4-posi-tion of its pyridine ring. (’552 File History, DRLRAB 292-93.) Fan concluded that the “[prior] art compounds are homo-logs of the claimed compounds rendering the claimed compounds unpatentable.” (Id. at 293.) The rejection of the rabepra-zole claims was not based on lack of novelty. (Ds. Joint R. 56.1 Stmt. ¶ 42.) Eisai reacted to this first rejection in various ways. On March 21, 1989, Eisai attorney Crawford offered a response that addressed both the structural and functional distinctiveness of rabeprazole. With respect to chemical structure, the response distinguished rabeprazole’s 4-position sub-stituent, methoxypropoxy, from those of compounds in the prior art. Eisai submitted that Junggren and GB ’523 disclosed only compounds bearing a methoxyethoxy group at the 4-position of the pyridine ring and “thus novelty is established” — presumably, although not explicitly, contrasting rabeprazole’s methoxypropoxy substituent. (’552 Patent File History, DRLRAB 429.) Further, Eisai pointed out that the “[specific compounds disclosed in [GB ’523] and [Junggren] are substituted at both the 3- and 5-position by methyl groups, as in the GB [’523] patent, or unsubstituted in both the 3- and 5-positions.” (Id. at DRLRAB 429, emphasis in original.) The response continued, “Applicants’ claims allow for the possibility of unsubstitution or a lower al-kyl at the 3-position with no substitution at the 5-position; preferably, the 3-posi-tion ... is methyl” — describing the asymmetrical pyridine-ring substitution pattern that is found in rabeprazole. (Id.) In addition to discussing structural traits, Eisai’s March 21 response also addressed the pharmacological properties of the claimed compounds. Eisai professed that compounds “in which the substituent at the 4-position is propoxymethoxy” exhibited “unexpected anti-ulcer activity.” (’552 Patent File History, DRLRAB 429.) It also submitted additional pharmacological comparisons with omeprazole, alleging omeprazole’s overall inferiority with respect to acid-inhibition and post-dosage recovery. (Id. at DRLRAB 541.) The response sought to justify Eisai’s choice of omeprazole as a comparator: As ... the [prior] art shows a preference for a specific compound currently under development and known as Ome-prazole, ... applicants have compared their elected compound with Omeopra-zole [sic ] and not compounds more nearly structurally related to the claimed compounds.... This is appropriate in accordance with In re Fouche, [439 F.2d 1237 (C.C.P.A.1971),] where the Court accepted a showing of unexpected advantage over a structurally more remote compound because the pri- or art clearly showed a preference for this structurally more remote compound. (’552 Patent File History, DRLRAB 430.) In a May 4, 1989, “Supplemental Response,” Eisai offered still further omepra-zole-related arguments in favor of its claimed compounds’ superiority, again explaining its choice of omeprazole as comparator: “The prior publications and patents describe a host of substituted benzimida-zole compounds having antisecretory activity.... Among these compounds, the single most interesting compound is known as omeprazol[e].” (’552 Patent File History, DRLRAB 437-38.) The response presented certain test comparisons as showing the superior acid-inhibition properties of Ei-sai’s claimed compounds. (Id. at 438-39.) Also in response to the first rejection, Eisai submitted a copy of a prior-art application to European Patent No. 167,943 (referred to as “Beecham”) which it had mentioned in the ’552 patent application. (’552 Patent File History, DRLRAB 354-418.) The Beecham application discloses the asymmetric pyridine-ring substitution pattern of rabeprazole (substitutions at the 3- and 4-positions, with none at the 5-posi-tion), but does not disclose a methoxypro-poxy or methoxyethoxy group at the 4-position. (See id.) B. Second Rejection and Eisai’s Response On July 14, 1989, unsatisfied by Eisai’s further submissions, Fan issued her second rejection of the rabeprazole claims based on the same prior art references. Referring to Eisai’s March 21 submission asserting the distinctiveness of rabepra-zole’s asymmetrical substitution pattern, she expressed incomprehension, writing, “The claimed compounds encompass both 3.5 positions [3- and 5-positions] substituted by lower alkyl, thus the statement at middle part of page 9 of applicants’ remark is not understood.” (’552 Patent File History, DRLRAB 441.) Additionally, Fan rejected Eisai’s reasoning in submitting comparison data for omeprazole rather than for a structurally closer prior-art compound: “The rationale of In re Fouche does not apply herein since isomeric difference [from the prior art] is noted therein whereas in the instant case homologous difference exists. Furthermore, a single compound is claimed in [F]ouche whereas a great many compounds are claimed in the instant case.” (Id.) She continued, “In the unpredictable medicinal field, one can not assume a compound’s pharmaceutical activity. Actual comparison has to be made in order to establish unexpected property.” (Id.) Crawford spoke with Fan on August 3, 1989, after she rejected the rabeprazole claims for the second time. (P.R. 56.1 Stmt. ¶ 56.) Fan’s record of the discussion states, in pertinent part, “If applicants are willing to limit the invention to [rabepra-zole], then only methoxyethoxy cpd need [sic ] to be compared.” (’552 File History, DRLRAB 449.) On December 28, 1989, Crawford filed a continuation of the rabeprazole application, to avoid expiration of the claims. C. Third Rejection and Eisai’s Response On July 17, 1990, Fan issued her third rejection of the rabeprazole application. She reiterated reasons from prior rejections, including that the claimed compounds were obvious in light of prior art, that Eisai’s argument concerning asymmetric substitution was “not understood,” that Eisai’s rationale for comparing only omeprazole was not persuasive, and that “[a]ctual comparison has to be made in order to establish unexpected property.” (’552 Patent File History, DRLRAB 455-56.) This time, however, she added, “The closest prior art compounds should be compared with the claimed compounds.” (’552 File History, DRLRAB 455.) “In the instant case,” she continued, certain prior-art compounds “should all be compared,” identifying in particular Example 27 of Junggren and “the compounds of EP 74841,” a “newly cited” prior art application that Fan referred to in her third rejection as “Carlsson.” (Id. at 455, 457.) Following Fan’s third rejection of the ’552 patent application, Eisai both narrowed its claims and attempted to strengthen its substantive case. On January 11, 1991, Eisai submitted an amendment, limiting its claims to only those relating to rabeprazole. (’552 Patent File History, DRLRAB 464-66.) On the same date Eisai submitted a Rule 132 declaration — known in this litigation as the “Fujisaki Declaration,” as its contents are attested by Eisai inventor Hideaki Fuji-saki — purporting to show rabeprazole’s superior performance in an in vitro acid-inhibition test comparing three compounds, Example 27 of Junggren and two others. (’552 Patent File History, DRLRAB 468-471.) “I compared the ... four compounds for their ability to inhibit H+K+ATPase, an assessment of the compound’s ability to inhibit the secretion of gastric acid,” Fujisaki reported. (Id. at 469.) None of the three comparators (compounds 2, 3, and 4) shares rabeprazole’s (compound 1) asymmetrical pyridine-ring substitution pattern, instead exhibiting substitution or no substitution at both their 3- and 5-positions. (Id. at DRLRAB 470.) But in an accompanying submission by Crawford, Eisai did not mention the asymmetry feature as a factor distinguishing rabeprazole from the comparators, emphasizing instead rabeprazole’s particular 4-position substituent: “[T]he compound of the invention having a methoxy-propoxy at the 4' position of the pyridine ring ... exhibits surprisingly unexpected [acid-]inhibitory effects ... in comparison with closely related compounds of the type referred to by the examiner. Here attention is invited to item 5, page 3 of the examiner’s letter where applicants have indeed compared the closest sulphonyl compound ethoxy methoxy with the claimed compound.” (Id. at DRLRAB 466.) That specified item, Junggren Example 27, like the other two comparators referred to in the Fujisaki Declaration, bears a methox-yethoxy, instead of rabeprazole’s methoxy-propoxy, at the 4-position of its pyridine ring. (Id. at 470.) Soon after, on April 3, 1991, Fan allowed the rabeprazole application to issue as patent ’552. (’552 Patent File History, DRLRAB 473.) The patent’s file history does not reveal why Fan ultimately decided that Eisai should receive the rabepra-zole patent. II. Prosecution of the Co-Pending Prosecution On June 16, 1988, approximately seven months after filing the application for the ’552 patent, Eisai via attorney Crawford filed the application for U.S. Patent No. 5,708,013 (“’013 patent”). (’013 Patent File History, DRLRAB 2281.) The ’013 patent application listed the same 14 inventors as did the ’552 patent application (P.Ex. 1, ’552 Patent; P.Ex. 2, ’013 Patent), and claimed inter alia a compound similar to rabeprazole in structure, prior art, and asserted properties. (’013 Patent File History, DRLRAB 2282.) Indeed, Eisai had written into its rabepra-zole application a limitation purporting to exclude certain similar compounds — including the compound covered by the ’013 application — from, being considered as part of the ’552 application. (’552 Patent File History, DRLRAB 230-34.) Eisai prosecuted the two patent applications separately before different PTO examiners and, during some three years’ overlap in the pendency of the two prosecutions did not disclose in either one the existence of, or any occurrences during, the other. (See ’552 Patent File History and ’013 Patent File History for identities of different examiners and absence of disclosure.) There is no evidence that Fan knew of the ’013 application, or that the examiners of that application knew of the ’552 application. The structure of the compound claimed in the ’013 application differs from rabep-razole’s by a single methylene unit (CH2) at the 4-position of the pyridine ring. It there bears a methoxyethoxy (OCH2CH2 OCH3) substituent, where rabeprazole bears a methoxypropoxy (OCH2CH2CH2 OCH3) substituent. The two compounds are otherwise structurally identical. (P. Mem., glossary at 7-8.) The similarity but for one methylene unit renders the two compounds homologous. Like defendants, the Court will refer to the compound claimed by the ’013 application as the “ethyl homolog” of rabeprazole, after the ethyl segment that differs from rabeprazole’s propyl segment. (Teva R. 56.1 Stmt. ¶ 24.) Eisai pursued both rabeprazole and the ethyl homolog for their gastric-acid inhibiting properties. (Teva R. 56.1 Stmt. ¶¶ 32-35, 49, for citations to contemporaneous acid-inhibition tests of both compounds by Eisai and to portions of the patent file histories of both compounds making similar assertions about their inhibitory properties). Eisai also made several identical, noteworthy representations in both prosecutions, for instance identifying Junggren and especially Junggren’s omeprazole compound as prior art and reporting that both homologs showed “unexpectedly ... potent inhibitory activity.” (Id. at ¶¶ 48-49, for citations to comparable portions of the patent file histories of the two compounds). A. First Rejection and Eisai’s Response On April 21, 1989, the PTO rejected the ethyl homolog claim (claim 8) of the ’013 application pursuant to 35 U.S.C. § 102(b), that is, for lack of novelty — specifically, for being “anticipated by” the Junggren prior art reference, which also appeared in the ’552 patent prosecution. (’013 Patent File History, DRLRAB 2471.) In the same action, the PTO rejected claims in the ’013 application other than the ethyl homolog for being obvious in light of a combination of Junggren and either of two prior art references not mentioned in the ’552 patent prosecution. One of these two references, which is significant to the issues in this case, is referred to by the parties as “Byk Gulden.” (Id. at DRLRAB 2473.) The PTO rejection reads: The difference between the Junggren reference [and] applicant’s claimed compounds [9,13, and 17] is the trifluorome-thyl group on the benzene ring of the benzimidazole. Both [Byk Gulden] and Rainer teach trifluor[o]methyl substitution of the benzene ring in similar compounds .... Since these compounds are all useful as gastric inhibitors and are all closely related in structure, one of ordinary skill would be motivated to combine the reference to produce applicant’s compounds. (Id.) This comment seems clearly to refer to claims other than the ethyl homolog, as the benzimidazole ring of the ethyl homo-log' — like that of rabeprazole — does not exhibit a trifluoromethyl substituent. (Compare diagrams of rabeprazole, the ethyl homolog, and Byk Gulden’s “WO ’646” compounds at P. Mem., glossary at 7-8.) Eisai responded to the PTO’s first rejection of the ’013 application in much the same way it did to the first rejection of the rabeprazole application, namely by emphasizing the asymmetrical pyridine-ring substitution pattern of Eisai’s claimed compounds and asserting superiority to omeprazole. On October 20, 1989, Crawford on behalf of Eisai narrowed the ’013 patent application claims and argued: The outstanding [rejection] ... cites and applies primarily Junggren ... either alone as an anticipation of certain claims or combined with other references.... Junggren ... contains identical substit-uents in the 3- and 5-positions.... By contrast, in the claims of the present application, the 5-position of the pyridine ring is always occupied by hydrogen (that is, it is unsubstituted), while the 3-position contains methyl. (’013 Patent File History, DRLRAB 2507; emphasis in original.) Also as in the ra-beprazole prosecution, Eisai urged its claimed compounds’ superiority to omepra-zole in inhibiting gastric acid secretion. (’013 Patent File History, DRLRAB 2507-08.) Going beyond its rabeprazole argument, however, in prosecuting the ’013 application Eisai not only argued omepra-zole’s inferior efficacy but also its lack of asymmetrical substitution: “Note that omeprazole has a methyl group on both the 3- and 5-positions of the pyridine ring, [and] thus may be considered symmetrical in this regard.” (Id. at DRLRAB 2508, emphasis in original.) Crawford further wrote, “Considering these structural differences and the associated differences (improvements) in gastric inhibitory activity as compared with even the preferred compounds of [Junggren] ... the examiner will quickly appreciate the inventiveness and patentability of the claims now under review.” (Id. at DRLRAB 2508-09.) B. Second Rejection and Eisai’s Response These arguments faded to persuade the ’013 application’s examiners. On December 6, 1989, the PTO again issued a rejection. This tíme, the ethyl homolog claim, along with others, was specifically rejected “under 35 U.S.C. [§ 102(b)] as anticipated by or, in the alternative, under 35 U.S.C. [§ ] 103 as obvious over Jung-gren ... in view of [Byk Gulden].” (’013 Patent File History, DRLRAB 2631.) Unlike the previous rejection, which had cited Byk Gulden in denying claims other than the ethyl homolog, this rejection clearly cited Byk Gulden — a prior art reference never volunteered by Eisai in either prosecution — directly regarding the ethyl homo-log of rabeprazole. The PTO’s December 6,1989, action also dismissed Eisai’s asymmetrical-substitution argument, finding that the prior art actually revealed this feature. “Junggren ... is not committed just to the symmetrical substituents. The generic formula discloses instant compounds by teaching asymmetrical substituents at the R3 and R5 positions. [Certain specified examples of Junggren] ... all teach asymmetrical sub-stituents at the R3 and R5 positions.” (’013 Patent File History, DRLRAB 2631.) Junggren combined with Byk Gulden rendered the ethyl homolog claims unpatentable, the PTO determined, because “[Byk Gulden] discloses compounds which teach methoxyethoxy at the 4-position and methyl at the 3-position” — precisely the 3- and 4-position substituents of the ethyl homolog. (Id.) The rejection pointed to specific compounds in Byk Gulden that served to obviate Eisai’s claims. (Id.) “One of ordinary skill in the art would be motivated to combine these references to produce the applicants’ claimed compound,” the rejection concluded. (Id.) The PTO also cited yet another combination that rendered the ethyl homolog claims unpatentably obvious. Byk Gulden combined with another prior art application, Carlsson — which, as described above, the ’552 patent examiner Fan had mentioned as a prior art compound of rabep-razole — taught asymmetrical substitution at the 3- and 5-positions and a methoxye-thoxy substituent at the 4-position, according to the PTO. (’013 Patent File History at DRLRAB 2632.) Eisai’s data purporting to demonstrate the pharmacological superiority of the ethyl homolog claims over omeprazole were dismissed as “not ... persuasive to overcome prima facie obviousness.” (Id.) Eisai tried again on June 6, 1990, with another submission responding to the second rejection of its ’013 patent application. In this submission, Crawford sought to diminish the import of the prior-art teaeh-ings the PTO had cited, arguing that they were “broad” and “generic” and should not, in light of legal precedent, wholly preclude the patentability of later, more specific claims. (’013 Patent File History, DRLRAB 2646.) Eisai then asserted “evidence of unexpectedly good inhibition of gastric secretion,” as it had in the rabep-razole prosecution, as a basis for patenta-bility. (Id.) Its response emphasized, again, the pyridine-ring substitution pattern: “The specific selection of the two substituents [methyl at the 3-position and methoxyethoxy at the 4-position] and [nonsubstituent] hydrogen on the pyridine ring provides the strong ... gastric secretion inhibitory activity.” (Id. at DRLRAB 2646-47.) Eisai then urged that Junggren and Carlsson did not disclose compounds featuring this pyridine-ring structure. (Id.) It did not address the PTO’s Byk Gulden findings here, or at any point in either prosecution. C. Final Rejection On August 9, 1990, in a “final” action, the PTO rejected Eisai’s arguments on behalf of the ethyl homolog claims. (’013 Patent File History, DRLRAB 2651.) Squarely countering Eisai’s interpretations of Junggren and Carlsson, examiner Joseph McKane spelled out, “The prior art teaches methyl at the 3-position, hydrogen [i.e., nonsubstitution] at the 5-position, and methoxyethoxy at the 4-position.” (Id. at DRLRAB 2651-52.) He concluded: The compounds in the prior art are used for inhibiting gastric acid secretion. Since the compounds of the prior art and the claimed compounds have the same utility and possess the same chemical and physical properties!,] it would have been obvious to one of ordinary skill in the art to produce applicants^] claimed compounds. Applicants have not overcome a prima facie case of obviousness. In [the] absence of unexpected or unobvious beneficial properties^] the rejection would not be overcome. (Id. at 2651.) Eisai did not further pursue its claims to the ethyl homolog. As noted above, it pressed ahead instead with the rabepra-zole application, which concluded successfully with the issuance of the ’552 patent in April 1991. PROCEEDINGS IN THE PRESENT ACTION In August 2003, Defendants Teva and Reddy each filed an ANDA with the FDA, hoping to obtain approval to market generic rabeprazole-based products before expiration of Eisai’s ’552 patent. (Ds. Joint R. 56.1. Stmt. ¶¶ 7-8). The expedited-approval statute requires that applicants file a certification regarding the status of the already approved drug. See Yamanouchi Pharmaceutical, 231 F.3d at 1342 (describing statutory scheme). Defendants filed “paragraph IV” certifications, so known for the statutory subsection invoked, claiming that Eisai’s patent “is invalid or will not be infringed by the manufacture, use, or sale of the new drug” proposed. (Ds. Joint R. 56.1 Stmt. ¶¶ 7-8, citing certifications pursuant to 21 U.S.C. § 355(j)(2)(A)(vii)(IV).) Eisai promptly filed these actions alleging patent infringement. Teva and Reddy have conceded infringement to the extent contemplated under the Hatch-Waxman regime. (Ds. Joint R. 56.1 Stmt. ¶¶ 9-11). Reddy has stipulated to the validity of the ’552 patent. See Stipulation and Order, June 23, 2004, Docket No. 03 Civ. 9053(GEL). Although Teva argues that the rabeprazole claims are invalid as obvious, this Court has rejected that argument in a separate Opinion. See note 2 supra. Thus, the defendants’ only remaining defense to be resolved in connection with this motion is their contention that Eisai engaged in inequitable conduct during prosecution of the ’552 patent and should therefore be stripped of the right to enforce it. They charge, in brief, that Eisai committed inequitable conduct by intentionally and with respect to material information: (a) failing to disclose the co-pendency of, and rejections and substantive developments during, the similar ’013 patent application, (b) misrepresenting by selective disclosure the patentability of ra-beprazole’s structure and properties, and (c) failing to disclose certain prior art. Eisai now moves for summary judgment rejecting these charges and finding that plaintiffs did not engage in inequitable conduct. LEGAL STANDARDS I. Summary Judgment Summary judgment shall be granted “if the pleadings, depositions, answers to interrogatories, and admissions on file, together with the affidavits ... show that there is no genuine issue as to any material fact and that the moving party is entitled to judgment as a matter of law.” Fed.R.Civ.P. 56(c). A “genuine issue of material fact” exists if the evidence is such that a reasonable jury could find in favor of the non-moving party. Holtz v. Rockefeller & Co., 258 F.3d 62, 69 (2d Cir.2001). The moving party bears the burden of establishing the absence of any genuine issue of material fact. Anderson v. Liberty Lobby, Inc., 477 U.S. 242, 256, 106 S.Ct. 2505, 91 L.Ed.2d 202 (1986). In deciding a summary judgment motion, the court must “resolve all ambiguities and draw all reasonable references in the light most favorable to the party opposing the motion.” Cifarelli v. Vill. of Babylon, 93 F.3d 47, 51 (2d Cir.1996). In addition, the court is not to make any credibility assessments or weigh the evidence at this stage. Weyant v. Okst, 101 F.3d 845, 854 (2d Cir.1996). The nonmoving party, however, may not rely on “conclusory allegations or unsubstantiated speculation.” Scotto v. Almenas, 143 F.3d 105, 114 (2d Cir.1998). The non-moving party “must do more than simply show that there is some metaphysical doubt as to the material facts,” Matsushita Elec. Indus. Co., Ltd., v. Zenith Radio Corp., 475 U.S. 574, 586, 106 S.Ct. 1348, 89 L.Ed.2d 538 (1986), and must make a “showing sufficient to establish the existence of [every] element essential to that party’s case, and on which that party will bear the burden of proof at trial.” Celotex Corp. v. Catrett, 477 U.S. 317, 322, 106 S.Ct. 2548, 91 L.Ed.2d 265 (1986). II. Inequitable Conduct In attempting to perfect its claim to rabeprazole, Eisai, like all patent applicants, was required to demonstrate the novelty and nonobviousness of its claimed invention. 35 U.S.C. §§ 102, 103. It was also required to comply with all other rules and standards of patent prosecution. As patent prosecution is an ex parte process, and the PTO’s investigative ability limited in time and resources, applicants seeking exclusive rights to an invention must fulfill a special obligation of candor and good faith to the PTO. Norton v. Curtiss, 57 C.C.P.A. 1384, 433 F.2d 779, 793-94 (C.C.P.A.1970). At the time of the disputed events, PTO regulations stated the duty, in' pertinent part, thus: A duty of candor and good faith toward the Patent and Trademark Office rests on the inventor, on each attorney or agent who prepares or prosecutes the application and on every other individual who is substantively involved in the preparation or prosecution of the application and who is associated with the inventor, with the assignee or with anyone to whom there is an obligation to assign the application. All such individuals have a duty to disclose to the Office information they are aware of which is material to the examination of the application. Such information is material' where there is a substantial likelihood that a reasonable examiner would consider it important in deciding whether to allow the application to issue as a patent. The duty is commensurate with the degree of involvement in the preparation or prosecution of the application. 37 C.F.R. § 1.56(a) (1987). There is no exception to this principle. An applicant is subject to the duty of candor even (indeed, especially) if making a disclosure would completely derail its prospects. A breach of this duty constitutes inequitable conduct and renders all claims of even a valid patent unenforceable. Molins PLC v. Textron, Inc., 48 F.3d 1172, 1178 (Fed.Cir.1995) (“Having determined that inequitable conduct occurred in the procurement of the ’563 patent, all claims of that patent are accordingly unenforceable.”); J.P. Stevens Co., Inc. v. Lex Tex Ltd., Inc., 747 F.2d 1553, 1559 n. 4 (Fed.Cir.1984) (where patent is held unenforceable because of applicant’s inequitable conduct, “we need not and do not address the patent validity ... issue[ ]”). To prove that inequitable conduct occurred in the prosecution of a patent requires showing clear and convincing evidence that the applicant affirmatively misrepresented or failed to disclose material information, or submitted false material information, with an intent to deceive the PTO. Purdue Pharma L.P. v. Boehringer Ingelheim GMBH, 237 F.3d 1359, 1366 (Fed.Cir.2001). If a court decides that evidence of the disputed conduct supports a threshold inference of materiality and deceptive intent, it must then weigh that evidence against all other circumstances to determine whether conduct so culpable as to justify unenforceability has indeed occurred. Baxter Int’l, Inc. v. McGaw, Inc., 149 F.3d 1321, 1327 (Fed.Cir.1998). The Federal Circuit has held that where information withheld or misrepresented is proved highly material, misconduct may be found on a lesser showing of intent — the inference being that, when information is so clearly related to a claim’s patentability, its miscommunication can hardly be thought innocent. See GFI, Inc. v. Franklin Corp., 265 F.3d 1268, 1275 (Fed. Cir.2001) (“[A] patentee facing a high level of materiality and clear proof that it knew or should have known of that materiality, can expect to find it difficult to establish ‘subjective good faith’ sufficient to prevent the drawing of an inference of intent to mislead.”) (citation omitted); see also Purdue Pharma L.P. v. Endo Pharmaceuticals, Inc., 438 F.3d 1123, 1134 (Fed.Cir.2006). A. Materiality As the Federal Circuit Court of Appeals has done with patents prosecuted prior to the PTO’s 1992 amendment of its rules, this Court here applies the judicially-adopted standard of materiality set forth in the pre-1992 version of 37 C.F.R. § 1.56, as quoted above. Dayco Prods., Inc. v. Total Containment, Inc., 329 F.3d 1358, 1364 (Fed.Cir.2003); cf. Purdue Pharma L.P., 438 F.3d at 1129 (“Because all of the patent applications at issue ... were pending on or filed after March 16, 1992, we look to the current version of Rule 56, rather than the pre-1992 version of the rule”). The rule provides that “information is material where there is a substantial likelihood that a reasonable examiner would consider it important in deciding whether to allow the application to issue as a patent.” 37 C.F.R. § 1.56(a) (1987). Information might be clearly material, because it relates to novelty or obviousness. See 35 U.S.C. §§ 102, 103. Yet, while information such as obviating prior art may be quintessentially material, “[mjateriality is not limited to prior art but instead embraces any information that a reasonable examiner would be substantially likely to consider important in deciding whether to allow an application to issue as a patent.” GFI, Inc., 265 F.3d at 1274 (emphasis in original), citing Akron Polymer Container Corp. v. Exxel Container, Inc., 148 F.3d 1380, 1382 (Fed.Cir.1998); Dayco, 329 F.3d at 1363, citing Akron Polymer. Withheld information, in other words, need not relate to a “but for” consideration of patentability in order to be held material. See Li Second Family Ltd. v. Toshiba Corp., 231 F.3d 1373, 1380-81 (Fed.Cir.2000) (“Information ... may be material even though it would not invalidate the patent.... [T]he test for materiality is whether a reasonable examiner would have considered the information important, not whether the information would conclusively decide the issue of pat-entability.”) Where an applicant is unsure of the materiality of any given information, it is “axiomatic that close cases should be resolved by disclosure, not unilaterally by applicant.” GFI, Inc., 265 F.3d at 1274, citing LaBounty Mfg., Inc. v. United States Int’l Trade Comm’n, 958 F.2d 1066, 1076 (Fed.Cir.1992) (internal quotation marks omitted). However, an applicant need not disclose even relevant information if that information is merely “cumulative,” or, redundant—and thus, practically speaking, not material—in light of the existing record. GFI, Inc., 265 F.3d at 1274, citing Halliburton Co. v. Schlumberger Tech. Corp., 925 F.2d 1435, 1440 (Fed.Cir.1991). It should be noted, though, that cumula-tiveness is a quite limited concept in this context. For instance, even if a certain combination of elements could be deduced from the existing the record by an examiner acting on her own, an applicant with knowledge of the combination nevertheless should disclose it. GFI, Inc., 265 F.3d at 1274 (“The [undisclosed] Durling references were not cumulative because no reference before the examiner disclosed this combination of required elements.”). B. Deceptive Intent Both materiality and intent are questions of fact, but in the sophisticated world of patent prosecution guilty applicants rarely leave “smoking gun” evidence of their deceptive intent. See Molins, 48 F.3d at 1180; Akron Polymer, 148 F.3d at 1384. Thus, courts often must infer intent where, after considering circumstances suggesting both bad- and good-faith conduct, the totality of evidence permits a “confident judgment that deceit has occurred.” Akron Polymer, 148 F.3d at 1384; see GFI, Inc., 265 F.3d at 1274-75; Frazier v. Roessel Cine Photo Tech, Inc., 417 F.3d 1230, 1235-36 (Fed.Cir.2005). The intent required for a finding of inequitable conduct is not merely a conscious and deliberate decision to withhold certain information, but also the intent specifically “to deceive or mislead the examiner into granting the patent.” Thermar-Tru Corp. v. Peachtree Doors Inc., 44 F.3d 988, 995 (Fed.Cir.1995). However, where an applicant has actual knowledge of material information but fails to disclose it, such deliberate withholding may be circumstantial evidence of the required intent to deceive. See, e.g., GFI, Inc., 265 F.8d at 1274-75. An even “stronger] case for deceptive intent” may exist where an applicant not only knowingly withholds material information, but also “ma[kes] an argument for patentability that could not have been made had the [information] been disclosed.” Id. at 1275. But, as already stated, even where it is merely found that undisclosed or misrepresented information is highly material, deceptive intent may be found without more, at least absent persuasive countervailing evidence of good faith. Id. The greater the materiality of the nondisclosure or misrepresentation, the easier to find culpable intent. Halliburton Co. v. Schlumberger Technology Corp., 925 F.2d 1435, 1439 (Fed.Cir.1991). C. Final Balancing If a court finds evidence adequate to support a threshold inference of materiality and deceptive intent, it must then weigh that evidence against all other circumstances to determine whether the applicant’s conduct was so culpable as to justify unenforceability. Baxter Int’l, Inc., 149 F.3d at 1327. The “challenged conduct must be sufficient to require a finding of deceitful intent in the light of all the circumstances.” Akron Polymer, 148 F.3d at 1383, citing Kingsdown Med. Consultants v. Hollister, Inc., 863 F.2d 867, 873 (Fed.Cir.1988) (internal quotation marks and emphasis omitted). Since patent prosecution by its nature entails selective presentation of information, it is easy enough for infringers to scatter defensive darts with the hope of hitting the inequitable-conduct bull’s-eye. Eisai accordingly urges this Court closely to police this “absolute plague” of an affirmative defense. (P. Mem. at 17, citing Burlington Indus., Inc. v. Dayco Corp., 849 F.2d 1418, 1422 (Fed.Cir.1988).) Caution is warranted. Courts have noted that inequitable conduct is a defense frequently raised, but not often proved, and have urged restraint in applying a defense that prevents enforcement of a valid patent. See, e.g., Preemption Devices, Inc. v. Minnesota Mining & Mfg. Co., 732 F.2d 903, 908 (Fed.Cir.1984); Kimberly-Clark Corp. v. Johnson & Johnson, 745 F.2d 1437, 1454 (Fed.Cir.1984); Burlington Indus., Inc., 849 F.2d at 1422. Nevertheless, where a charge has true aim and pinpoints provably culpable conduct, courts must in the interest of fairness strip the patent-holder of its ill-gotten exclusive right. Indeed, while defendants lodge numerous allegations of inequitable conduct, ultimate proof of just one will suffice to render the ’552 patent unenforceable. See GFI, Inc., 265 F.3d at 1275 (“Because the failure to disclose the Durling references alone supports unenforceability of the claims of the ’244 patent, we need not address the remaining references.”). At this stage in the proceedings, however, the Court is faced not with deciding after a full trial whether inequitable conduct has been proved, but with the quite different inquiry whether Eisai may win summary judgment that no inequitable conduct occurred. Eisai bears the burden of showing the lack of any issue of material fact as to each claim of inequitable conduct. Eisai is entitled to summary judgment only if it appears on the existing record that no reasonable factfinder could find by clear and convincing evidence— after a trial where credibility may be weighed and witnesses cross-examined— that Eisai committed inequitable conduct. DISCUSSION I. Nondisclosure of the Co-Pending Patent Application Defendants argue that summary judgment is precluded by their evidence relating to Eisai’s co-pending application for rabeprazole’s homolog. Defendants urge that information about the ethyl ho-molog application would have been important to rabeprazole’s examiner from the very moment it was filed, but that such information became especially material to rabeprazole’s fate once rejections in the co-pending application began to issue. They charge that Eisai deliberately and repeatedly failed to inform Fan about the ethyl homolog application, even as developments suggested its increasing materiality, and that Eisai thus engaged in inequitable conduct. Eisai’s efforts to negate the existence of genuine issues of material fact as to the wrongfulness of its nondisclosures of the co-pending ethyl homolog application entirely fail. Defendants offer a sufficient showing upon which a reasonable factfin-der could, by the requisite elear-and-con-vincing standard, deem Eisai culpable of inequitable conduct on these, grounds. A. Fact of Co-Pendency Defendants allege that the mere fact of the ethyl-homolog application’s concurrent existence was information that a reasonable examiner would have considered important to know in deciding whether to grant the same applicant a patent for ra-beprazole. They argue that the two compounds were “patentably indistinct” and that the rabeprazole examiner — had she known about the co-pending ethyl homolog claims — could at the least have issued a “provisional” double-patenting rejection to avoid bestowing duplicative patent rights on Eisai. Given the compounds’ close similarity and the prohibition against double-patenting, defendants charge, Eisai knew or should have known to disclose the co-pendency of the ’013 application in its ’552 patent prosecution. Defendants further contend that deceptive intent may be inferred from the clear materiality of the undisclosed fact. {See Teva Mem. 18-24; Reddy Mem. 24-31.) Both PTO rules and case law discourage the granting of duplicative patent rights not just as between different applicants— to protect an owner’s exclusive right — but also as to a single applicant, to avoid overprotecting that right. In the period relevant here, the MPEP stated that “if an inventor has different applications pending in which similar subject matter but patent-ably indistinct claims are present that fact must be disclosed to the examiner of each of the involved applications.” M.P.E.P. § 2001.06(b)(1986). Patent examiners were instructed to issue “provisional” double-patenting rejections in such overlapping applications, essentially raising an internal flag that substantially similar claims were in play. (Stoner, Deck 1 ¶¶ 90-91; Smith Decl. ¶¶ 85.) The rationale for these rules, as has been recognized by the courts, was to avoid granting overextensive ownership periods or multiple transferrable interests regarding substantially similar claims. Dayco, 329 F.3d at 1365-66; Akron Polymer, 148 F.3d at 1382; In re Longi 759 F.2d 887, 892 (Fed.Cir.1985). In affirming the PTO’s denial of certain claims for asserting “the same invention [as another application] or an obvious modification thereof,” the Federal Circuit has explained that the worry is not just private wrongdoing but public harm: “[T]he maintenance of a patent that creates double patenting is ... an imposition on the public.” In re Lonardo, 119 F.3d 960, 965-66 (Fed.Cir.1997), citing, e.g., In re Longi 759 F.2d at 892. Hence, the Federal Circuit in Dayco Products, Inc. v. Total Containment, Inc. — addressing a summary judgment ruling that a patent-holder had engaged in inequitable conduct partly by failing to disclose a “substantially similar” application also prosecuted in its name — held that, where “disclosure of the [other, commonly owned] application .... could have led to double patenting rejections in the applications that issued as the patents-in-suit_the pendency of [that other] application was, therefore, material.” Dayco, 329 F.3d at 1361, 1365-65. The court mentioned MPEP § 2001.06(b) but also invoked the relevant judicial standard of disclosure: “This court has held that under the ‘reasonable examiner’ standard of materiality, an application was highly material to the prosecution of an application where it could have conceivably served as the basis of a double patenting rejection.” Id. at 1365 (citation, internal brackets, and quotation marks omitted). Defendants do not merely argue that the ethyl homolog was similar enough to ra-beprazole that it could conceivably have triggered a double-patenting rejection of rabeprazole. Rather, they argue — seemingly to accord with the MPEP language— that the two compounds were “patentably indistinct” as a matter of law, because they shared “very close structural similarities and similar utilities [and], without more [were] ... prima facie [obvious].” (Teva Mem. 19, citing In re Grabiak, 769 F.2d 729, 731-32 (Fed.Cir.1985) (internal quotation marks omitted); Reddy Mem. 25.) Eisai objects to defendants’ characterization of the disputed compounds as “patent-ably indistinct,” denying that the compounds presented the prima facie case of obviousness. (Eisai Reply. Mem. 24.) Indeed, the Federal Circuit in In re Grab-iak, et al, upon which defendants rely for their prima facie obviousness argument, cautioned that “generalization should be avoided insofar as specific chemical structures are alleged to be prima facie obvious one from the other.” 769 F.2d at 731. In that case, the PTO’s rejection was reversed when appellant showed that the application for the purportedly obviating compound did not contain the necessary teachings to make the alteration toward the challenged compound. Id. The Court reversed the PTO’s prima facie obviousness determination, because “one of ordinary skill in the art” would not have been motivated to produce the disputed compound based solely on the existing art. Id. at 732. At this stage, however, it is not necessary to resolve whether the two compounds were, in fact, patentably indistinct. Nor is it clear that this is the showing defendants would have to make at trial, to sustain an inequitable conduct judgment by the judicial standard. While the Dayco court incorporated the label in its mention of the MPEP procedure, the contested applications there were actually dubbed “substantially similar.” 329 F.3d at 1361. The court held material the existence of undisclosed claims that “were in some respects substantially identical to the claims of the patents-in-suit,” without declaring one way or the other that the claims were patentably indistinct. Id. at 1361. See also McKesson Information Solutions, Inc. v. Bridge Medical, Inc., 02 Civ. 2669(FCD), 2006 WL 1652518, at *18 (E.D.Cal. June 13, 2006) (“Beyond meeting the Dayco ‘substantially similar’ test, the two rejections ... are material for [an] independent reason,” finding inequitable conduct partly based on patentee’s unjustified failure to disclose rejections in a co-pending, similar prosecution). For now, it is unnecessary to pinpoint the precise degree of similarity required, for to survive summary judgment defendants need only show that a genuine issue of material fact exists as to the substantial likelihood that rabeprazole’s examiner would have wanted to know of the ’013 patent application’s co-pendency for the purpose of precluding overlapping patents. If a reasonable fact-finder could conclude that the information is sufficiently material, defendants will also have shown enough to raise an issue as to Eisai’s intent in not disclosing. Eisai has failed to show the absence of a genuine issue as to the patentable indistinctness, or substantial similarity, of the two compounds. Besides conclusorily stating that “the rabeprazole and ethyl homo-log claims do not overlap” and are “different” (P. Reply Mem. 25), Eisai offers little to deny that the nearly identical claims were anything other than mutually obviating. The only possible evidence to that end is Eisai’s specific mentions of rabepra-zole’s methoxypropoxy substituent in arguments to examiner Fan, which could be construed as distinguishing the two homo-logs by their sole differing feature. But those submissions did not address the ethyl homolog at all and cannot conclusively prove, without more, that the difference of the single methylene unit of rabeprazole served to render it patentably distinct from the ethyl homolog. Teva notes that Eisai patenting head Taniguchi knew the separately claimed compounds were quite similar, and that he testified, “[0]ne was rabeprazole and the other was a derivative of rabeprazole ... a related derivative.” (Teva Mem. 19, 34; see also Taniguchi Dep. 37:22-38:12; 77:3-25.) Teva’s expert opines that the pharmacological data offered in both applications showed the compounds to be functionally, not just structurally, similar. (Forte Rep. ¶ 55.) While Eisai’s patenting expert testifies that the ethyl homolog application was “substantially more abbreviated” than the rabeprazole application — for instance, in its lack of in vivo animal data — he does not assert with any specificity that the applications were patentably different. (Killworth Decl. ¶ 74.) Evidence of Eisai’s unilateral “proviso” limitation, purporting to exclude the ethyl homolog compound from the ’552 patent application, does not negate the question whether this action sufficed meaningfully to differentiate the claims. The ’013 and ’552 patent applications otherwise shared numerous, significant similarities. Indeed, Eisai does not waste much effort disputing that the claims were so similar that examiner Fan could have issued, as defendants allege, a “provisional” double-patenting rejection. (P. Mem.37.) Instead, it protests that a “provisional” rejection is so insignificant an occurrence in the process of patenting that information withheld cannot be found material on this ground. Only when a co-pending application is actually granted — and a “provisional” double-patenting rejection thus transformed into a “real” one — Eisai argues, can its existence become material to the patentability determination of the other application. (Id, arguing that “[a] ‘provisional rejection’ is not a ‘rejection.’ ”) In this vein, Eisai’s expert Killworth testifies that “‘double patenting’ is based on the claims of the patent as they are issued, and not the claims of a patent application.” (Killworth Decl. ¶ 93, emphases added.) In other words, only if the ethyl homolog claims had actually issued, and issued first, does Eisai believe it might have had the duty to inform rabeprazole’s examiner about the other application. Pointing to the Dayco case, Eisai insists that the Federal Circuit has never “discussed] or analyze[d] whether a ‘provisional’ double patenting rejection would have been important to patentability.” (P. Mem. 38; see also P. Reply Mem. 19.) It is true that the word “provisional” does not appear in that case. Yet that decision rests nothing on the actual issuance of substantially similar patents, stressing rather the patent prosecutor’s duty to disclose any information that “could have led to double patenting rejections in the applications that issued as the patents-in-suit.” Dayco, 329 F.3d at 1365 (emphasis added). A “basis for establishing unpatentability is [a] potential double patenting rejection,” the Court held. Id. at 1366 (emphasis added). Notably, the court’s discussion focused on the materiality of a “co-pending” similar application, not of an already - issued similar patent. Id. at 1362 (emphases added); see also id. at 1365-66 (where “disclosure ... could have led to double patenting rejections in the applications that issued as the patents-in-suit .... the pendency of [that other] application was, therefore, material”) (emphases added). Eisai’s own patenting expert testified that PTO examiners take the time to check for the co-pendency of similar applications before deciding to issue a patent— indicating that such information is indeed important for a reasonable examiner to know. (Killworth Decl. ¶ 68, noting that examiner Fan before issuing the ’552 patent conducted an “Interference Search,” a step which is meant to turn up “co-pending applications claiming the same or obvious variations of the subject matter of the application at issue”) Eisai’s attempt to rely on the fortuitous, hindsight observation that the homolog claims never were approved — and that the rabeprazole claims therefore did not actually issue as a duplicative patent — would seem to turn the rationale of the disclosure duty on its head. As discussed, the duty covers not only “but for” considerations of patentability, but also less certain ones. There is no exception permitting applicants to withhold material information and avoid accountability if events happen to unfold in their favor. There is no question that the law discourages issuance of dupli-cative patents. Eisai’s submission that the rabeprazole examiner checked on her own for overlapping claims not only is irrelevant to deciding whether Eisai fulfilled its affirmative disclosure duty by the objective standard, but also serves to underscore the materiality of the information Eisai did not disclose. Also irrelevant is Eisai’s argument that a “provisional” rejection is unimportant because Eisai would not have had to respond to it (P. Mem.37), as materiality is not measured by the degree of associated applicant effort. Even if a “provisional” rejection would have been lifted as a matter of course the moment the ’552 patent claims were approved, as Eisai insists (id.), the law of inequitable conduct and of double-patenting counsels that the rabeprazole examiner should have been given the opportunity to make that decision. Eisai has hardly negated the existence of a triable issue as to whether the co-pending applications so resembled each other that a reasonable examiner of the rabeprazole claims would have wanted to know about the co-pending application to avoid issuing a duplicative patent. Nor has Eisai proved the lack of a genuine issue as to its intent in not disclosing the co-pendency of the ’013 patent application to the rabeprazole examiner. Besides disputing the materiality of the information, Eisai submits that its patent attorney and others involved in the ’552 patent application simply did not believe that their disclosure duty covered information from a “later-filed” application. (P. Reply Mem. 20; P. Mem. 43-44; Killworth Decl. ¶ 101.) Plaintiffs do not counter defendants’ argument (see, e.g., Teva Mem. 33), that, at the least, Eisai was put on notice of a potentially important overlap between the separate applications claiming homologs when Fan wrote in her first rejection of rabepra-zole, “[prior] art compounds are homologs of the claimed compounds rendering the claimed compounds unpatentable.” (’552 File History at DRLRAB 292-93.) Eisai instead protests that “there is no allegation that Eisai tried to ‘steer’ the ’013 patent application to a different examiner from the rabeprazole application.” (P. Reply Mem. 26.) But such “smoking gun” evidence of deception is not required. A reasonable factfinder need not accept protestations of ignorance where the materiality of the nondisclosure is great. Here, Eisai has neither diminished the degree of materiality nor offered exonerating evidence such that a reasonable factfinder could not infer that it intended to deceive rabeprazole’s examiner by withholding the fact of the ’013 patent application’s co-pendency. Case law strongly supports the conclusion that the failure to disclose material co-pending applications is powerful evidence of intent to deceive. The patentee in Day-co only escaped summary judgment of inequitable conduct by showing that it had actually disclosed the fact of co-pendency in one of the concurrent prosecutions. The court there ruled that the disclosure in one application left at least a triable issue as to the accused’s intent to deceive the PTO. 329 F.2d at 1366. Similarly, in Akron Polymer, the Federal Circuit reversed a finding of deceptive intent based on applicant’s failure to disclose the co-pendency of similar applications, because the applicant had actually disclosed in one of the prosecutions. That disclosure “point[ed] away from an intent to deceive,” the court concluded. 148 F.3d at 1384. However, it cautioned that, “[b]ut for the fact that [the accused] actually disclosed the fact of copendency of the two applications to the PTO ... it could be argued that the other facts in this case are sufficient to support a threshold finding of deceitful intent by clear and convincing evidence.” Id. Those “other facts” showed that “the same law firm and the same attorneys prosecuted both applications, and that those attorneys were aware of the similarity of the inventions disclosed in the two applications .... [and of] the possible consequences should the PTO find the inventions not patentably distinct.” Id. at 1383. Eisai has not offered any proof that it disclosed co-pendency in either the ’013 or the ’552 application process, nor any proof that the two applications were significantly different. Under such circumstances, a reasonable factfinder could find intent to deceive. B. Rejections Defendants in this case do not rely merely on the non-disclosure of the fact of the ’013 patent application’s co-pendency, but also on Eisai’s failure to disclose the rejections that ensued in that prosecution during consideration of the rabeprazole claims. Assuming the close similarity between the ethyl homolog and rabeprazole, defendants argue that the mere issuance of a rejection of one substantially similar claim is per se material to the co-pending prosecution of another. Further, they urge that the substantive reasons provided in the ethyl homolog’s rejections were themselves material to the rabeprazole application, arguing that Eisai should have disclosed these reasons because they were directly material to the rabeprazole application. 1. “Per Se Materiality” Defendants again point to Dayco, which holds in part that “a contrary decision of another examiner reviewing a substantially similar claim meets the ... [pre-1992] ‘reasonable examiner’ threshold materiality test of ‘any information that a reasonable examiner would substantially likely consider important in deciding whether to allow an application to issue as