Case 2:20-cv-00337-JRG Document 429 Filed 07/14/22 Page 1 of 13 PageID #: 16400
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`SEAGEN INC.,
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`v.
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`Plaintiff,
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`CASE NO. 2:20-cv-00337-JRG
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`IN THE UNITED STATES DISTRICT COURT
`EASTERN DISTRICT OF TEXAS
`MARSHALL DIVISION
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`DAIICHI SANKYO CO., LTD.,
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`Defendant, and
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`ASTRAZENECA PHARMACEUTICALS
`LP and ASTRAZENECA UK LTD.,
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`Intervenor-Defendants.
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`DAIICHI SANKYO COMPANY,
`LIMITED’S BENCH TRIAL BRIEF
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`Case 2:20-cv-00337-JRG Document 429 Filed 07/14/22 Page 2 of 13 PageID #: 16401
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`I.
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`INTRODUCTION
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`At the upcoming bench trial, Defendant Daiichi Sankyo Company, Limited (“Daiichi
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`Sankyo Japan”) will present evidence and argument establishing that the patent-in-suit, U.S. Patent
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`No. 10,808,039 (“the ’039 patent”), is unenforceable due to prosecution laches as well as invalid
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`under 35 U.S.C. § 112(b) for failure to claim subject matter that the inventors actually regarded as
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`their invention.
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`Prosecution laches is an equitable defense dating back to the early 1900s.1 Its application
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`serves an important public policy function of ensuring that a patentee who receives the right to
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`exclude others complies with its duty of disclosure.2 “A patent holder should know what he owns,
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`and the public should know what he does not.”3 The written description, claims, and prosecution
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`history of a patent serve “a public notice function” by making plain the boundaries of the inventor’s
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`claimed property right.4 This clarity is essential to promote progress because it enables efficient
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`investment in innovation.
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`Plaintiff Seagen Inc. (“Seagen”) unreasonably and inexcusably delayed—for 15 years—
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`1 Webster Elec. Co. v. Splitdorf Elec. Co., 264 U.S. 463, 465-66 (1924) (holding laches barred
`claims where patentee delayed more than eight years after the original application to bring
`broader claims, and finding such inaction to be “unreasonable delay and neglect on the part of
`the applicant and his assignee in bringing forward claims broader than those originally sought”).
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`2 See In re Bogese, 303 F.3d 1362, 1366, 1369 (Fed. Cir. 2002) (affirming Board of Patent
`Appeals and Interferences’ denial of patent application based on prosecution laches where Board
`found that the applicant’s unreasonable delay was “egregious in defeating the policy of the patent
`laws of promoting science and the useful arts” and that the harm of such delay included “delay in
`disclosure of the invention to the public”); see also Hyatt v. Hirshfeld, 998 F.3d 1347, 1352 (Fed.
`Cir. 2021) (identifying timely public disclosure as “a central goal of the patent system”).
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`3 Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722, 731 (2002).
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`4 See Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 344 F.3d 1359, 1369 (Fed. Cir.
`2003).
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`Case 2:20-cv-00337-JRG Document 429 Filed 07/14/22 Page 3 of 13 PageID #: 16402
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`before seeking the patent rights it now asserts against Daiichi Sankyo Japan. Consistent with the
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`testimony of Seagen’s inventors and employees during the jury trial, the evidence will show that
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`during those 15 years, Seagen’s disclosure never suggested it had invented the subject matter
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`claimed in its ’039 patent. It will further confirm that it was only after Seagen saw Daiichi Sankyo
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`Japan’s drug product, Enhertu®, the success it was achieving with cancer patients, and Daiichi
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`Sankyo Japan’s announcement that it had chosen to collaborate with AstraZeneca and not Seagen,
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`that Seagen filed claims notifying the public for the first time in 15 years that its purported
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`invention was not limited to drug products with monomethylvaline compounds (also known as
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`auristatin compounds, MMAE and MMAF in particular) in stark contradiction with the title and
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`abstract of the patent. The evidence will further show Daiichi Sankyo Japan was prejudiced by
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`Seagen’s delay, as in the interim, Daiichi Sankyo Japan
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`developing and commercializing Enhertu®.
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`Daiichi Sankyo Japan has a legal defense, distinct from the written description and
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`enablement defenses presented at trial, that Seagen’s claims are invalid under Section 112(b) of
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`the Patent Act, for failure to claim what the inventors regard as their invention. Daiichi Sankyo
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`Japan is amenable to presenting this legal argument to the Court, if necessary, in connection with
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`post-trial briefing pursuant to Rule 50 of the Federal Rules of Civil Procedure, rather than doing
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`so in connection with the upcoming bench trial. Nevertheless, in an effort to avoid any possible
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`assertion that Daiichi Sankyo Japan’s failure to present this defense at this juncture constitutes a
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`waiver, it is included herein.
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`Section 112(b) of the patent statute ensures that the public is informed of the bounds of the
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`claimed material covered by the patent’s exclusive rights and that a patent does not claim material
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`Case 2:20-cv-00337-JRG Document 429 Filed 07/14/22 Page 4 of 13 PageID #: 16403
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`inconsistent with what the named inventors view as their invention.5 This is a legal issue that
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`Daiichi Sankyo Japan has preserved and that the Court has not yet decided. (See Dkt. 328 at 9.)
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`The evidence will show that the inventors never regarded their invention to be the subject matter
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`Seagen claimed 15 years after filing the initial application to which Seagen claims priority. For
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`example, the ’039 patent specification is limited to ADCs with monomethylvaline compounds, as
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`are the title and abstract, yet the ’039 patent claims attempt to reach much broader to encompass
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`ADCs with any drug moiety. Because of at least this fundamental contradiction between the ’039
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`patent’s claims and specification, the claims fail to satisfy 112(b)’s requirement that they set forth
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`what the applicants regard as their invention, and are thus invalid.
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`II.
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`LEGAL STANDARDS
`A.
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`Prosecution Laches
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`Prosecution laches is an equitable affirmative defense to patent infringement that can
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`render a patent unenforceable. See Symbol Techs., Inc. v. Lemelson Med., Educ. & Rsch. Found.,
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`LP, 422 F.3d 1378, 1384-85 (Fed. Cir.), amended on reh’g in part, 429 F.3d 1051, 1051-52 (Fed.
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`Cir. 2005). Proving prosecution laches requires showing two elements: “(a) that the patentee’s
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`delay in prosecution was unreasonable and inexcusable under the totality of the circumstances;[6]
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`and (b) that the accused infringer suffered prejudice attributable to the delay.” Hyatt, 998 F.3d at
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`1362 (citing Cancer Rsch. Tech. Ltd. v. Barr Lab’ys, Inc., 625 F.3d 724, 728-29 (Fed. Cir. 2010)).
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`For the unreasonable and inexcusable delay element, courts examine “‘the totality of the
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`5 See Allen Eng’g Corp. v. Bartell Indus., Inc., 299 F.3d 1336, 1348-49 (Fed. Cir. 2002).
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`6 Some courts have articulated this element as “an unreasonable and unexplained delay in
`prosecution that constitutes an egregious misuse of the statutory patent system under a totality of
`the circumstances.” Hyatt, 998 F.3d at 1360 (quoting Cancer Rsch., 625 F.3d at 728);
`Personalized Media Commc’ns, LLC v. Apple, Inc., 552 F. Supp. 3d 664, 684 (E.D. Tex. 2021).
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`Case 2:20-cv-00337-JRG Document 429 Filed 07/14/22 Page 5 of 13 PageID #: 16404
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`circumstances, including the prosecution history of all of a series of related patents and overall
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`delay in issuing claims.’” Personalized Media, 552 F. Supp. 3d at 685-86 (quoting Hyatt, 998
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`F.3d at 1362). Courts apply an objective standard, evaluating “how a reasonable patent applicant
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`would prosecute his patent under plaintiff’s circumstances.” Reiffin v. Microsoft Corp., 270 F.
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`Supp. 2d 1132, 1155 (N.D. Cal. 2003). Courts may also look to a number of factors in determining
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`unreasonableness under the totality of the circumstances. See id. It is not required to show intent
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`to delay to establish prosecution laches; “unreasonable delay alone,” including culpable neglect,
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`“is sufficient.” Symbol Techs., Inc. v. Lemelson Med., Educ. & Rsch. Found., LP, 301 F. Supp. 2d
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`1147, 1156 (D. Nev. 2004), aff’d, 422 F.3d 1378 (Fed. Cir. 2005).
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`Courts have found delays of eight years following the first patent filing to present claims
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`to an alleged invention to be unreasonable. See Personalized Media, 552 F. Supp. 3d at 682, 686-
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`87, 690-91 (finding an eight-year delay between the filing of a patent application presenting new
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`claims and the original application to which it claims priority to be an unreasonable delay); see
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`also Webster Elec. Co. v. Splitdorf Elec. Co., 264 U.S. 463, 465 (1924) (same). This is consistent
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`with the notion that the public is “entitled to assume that what was not claimed is dedicated to the
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`public.” Mosaid Techs. Inc. v. Samsung Elecs. Co., 362 F. Supp. 2d 526, 553 (D.N.J. 2005). Such
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`delays are unreasonable due to their “adverse effect on businesses that were unable to determine
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`what was patented from what was not patented.” See Symbol Techs., 422 F.3d at 1386.
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`For the prejudice element, an accused infringer must show evidence of intervening rights,
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`i.e., that “either the accused infringer or others invested in, worked on, or used the claimed
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`technology during the period of delay.” Cancer Rsch., 625 F.3d at 729.
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`B.
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`35 U.S.C. § 112(b)
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`A patent’s specification must “conclude with one or more claims particularly pointing out
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`and distinctly claiming the subject matter which the inventor or a joint inventor regards as the
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`Case 2:20-cv-00337-JRG Document 429 Filed 07/14/22 Page 6 of 13 PageID #: 16405
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`invention.” 35 U.S.C. § 112(b). For a claim to comply with this requirement, two elements are
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`required: “first, [the claim] must set forth what ‘the applicant regards as his invention,’ and second,
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`it must do so with sufficient particularity and distinctness, i.e., the claim must be sufficiently
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`‘definite.’” Allen, 299 F.3d at 1348 (quoting Solomon v. Kimberly-Clark Corp., 216 F.3d 1372,
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`1377 (Fed. Cir. 2000)). These two elements are distinct inquiries. See Ancora Techs., Inc. v.
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`Apple, Inc., 744 F.3d 732, 739 (Fed. Cir. 2014).
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`For the first element, a patent claim is invalid where “it would be apparent to one of skill
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`in the art, based on the specification, that the invention set forth in a claim is not what the patentee
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`regarded as his invention.” Allen, 299 F.3d at 1349. In Allen, for example, the Federal Circuit
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`found claims invalid under § 112(b) where they were inconsistent with and contrary to the
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`specification, and the patentee admitted the facts establishing that contradiction. Id. This issue
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`presents a question of law for the Court to decide. See id. at 1344.
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`III. EVIDENCE TO BE PRESENTED AT TRIAL
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`In support of its prosecution laches and 112(b) defenses, Daiichi Sankyo Japan will present
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`live testimony from the following witness:
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` Daiichi Sankyo Japan expert witness regarding prosecution laches.
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`Additionally, Daiichi Sankyo Japan will present for the Court’s review relevant portions of
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`testimony given at the jury trial and/or at deposition in this action from the witnesses identified
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`below; Daiichi Sankyo Japan would like to present by video approximately 30 minutes of this
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`testimony and submit the rest by paper for efficiency:
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` Daiichi Sankyo Japan fact witness:
`o Dr. Glenn Gormley;
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` Daiichi Sankyo Japan expert witness:
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`Case 2:20-cv-00337-JRG Document 429 Filed 07/14/22 Page 7 of 13 PageID #: 16406
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`o Dr. John Lambert; and
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` Seagen fact witnesses:
`o Dr. Peter Senter;
`o Dr. Brian Toki;
`o Dr. Svetlana Doronina; and
`o Dr. Toni Beth Kline.
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`Daiichi Sankyo Japan will also present and introduce documentary evidence and deposition
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`testimony relied on by its prosecution laches expert, as well as cross-examination of any witnesses
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`presented by Seagen during the bench trial.
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`IV.
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`SEAGEN’S CLAIM IS BARRED BY PROSECUTION LACHES
`A.
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`Unreasonable And Inexcusable Delay By Seagen
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`The evidence will show that Seagen delayed more than 15 years between the filing of the
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`first provisional application to which the ’039 patent purportedly claims priority and the filing date
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`of the ’839 application that ultimately issued as the ’039 patent before presenting the claims at
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`issue in this case. This substantial delay was objectively unreasonable and inexcusable. See
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`Personalized Media, 552 F. Supp. 3d at 682, 686-87, 690-91; Webster Elec. Co., 264 U.S. at 465.
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`The totality of the circumstances, including the various factors courts may evaluate for this
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`element, Reiffin, 270 F. Supp. 2d at 1155, reinforce this conclusion.
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`The evidence will show the prosecution history of the ’039 patent was not typical within
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`the pharmaceutical and biotechnology industries, or patents generally. Seagen delayed for 15 years
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`between the first filing in the patent family and the ’839 application, and there is no reasonable
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`explanation for this 15-year gap. Further, when Seagen finally acted after that 15-year gap, it
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`significantly changed and broadened the scope of its purported invention. As discussed in Section
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`V, infra, the original patent filings and prosecution described purported inventions concerning only
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`Case 2:20-cv-00337-JRG Document 429 Filed 07/14/22 Page 8 of 13 PageID #: 16407
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`auristatin/dolastatin-type drug moieties, yet 15 years later, with the ’839 application and ’039
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`patent, Seagen substantially broadened the reach to purport to claim ADCs comprising any drug
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`moiety (plus a glycine and/or phenylalanine-only tetrapeptide linker not described anywhere in the
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`specification).
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`For 15 years after the first filing in the patent family, Seagen’s public statements and
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`indications were that its purported invention concerned only auristatin/dolastatin drug moieties.
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`This is consistent with testimony from Dr. Senter, who admitted that the ’839 application (which
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`led to the ’039 patent) was the first time the drug moiety was not limited to an auristatin or
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`dolastatin analog and that the claim wording changed. (Dkt. 374, Trial Tr. (Day 1) at 260:16-
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`261:5.) At no time during that 15-year gap did Seagen seek patent rights for or otherwise give any
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`indication publicly that it sought to pursue claims encompassing any drug moiety. Thus, for 15
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`years, Seagen gave the public the impression that its purported invention was limited to ADCs
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`with auristatin/dolastatin drug moieties, and gave no notice to the public that it would later seek to
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`broaden its purported claims to encompass ADCs with any drug moieties.
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`The evidence will further show that after having delayed 15 years, Seagen took steps to
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`rush the application process once undertaken, pursuing an accelerated prosecution of the ’839
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`application with the PTO’s Track One prioritized patent examination. Prior to suddenly seeking
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`accelerated prosecution in 2019, Seagen engaged in a five year holding pattern, by filing and then
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`abandoning two consecutive patent applications over a span of about four years from 2014-2018,
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`and keeping the chain of applications alive by filing a patent application in 2017 with claims for a
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`commercially meaningless research tool assay. The evidence will not show any explanation or
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`legitimate grounds for Seagen’s actions during this period.
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`The evidence will show that the change in Seagen’s prosecution, and its sudden haste to
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`Case 2:20-cv-00337-JRG Document 429 Filed 07/14/22 Page 9 of 13 PageID #: 16408
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`pursue prosecution of the asserted claims after a 15 year gap, coincided directly with and followed
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`directly after Daiichi Sankyo Japan’s public disclosure of DS-8201 and announcement of its $6.9
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`billion collaboration with AstraZeneca.
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`B.
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`Prejudice To Daiichi Sankyo Japan From Seagen’s Delay
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`The evidence at trial will show that Daiichi Sankyo Japan established intervening rights
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`based on its significant investment in, work on, and use of the accused technology. Daiichi Sankyo
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`Japan scientist Dr. Naito designed and synthesized DS-8201 in 2011. A year later, Daiichi Sankyo
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`Japan filed its first patent application covering its ADC technology, including DS-8201. As of
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`now, Daiichi Sankyo Japan has filed for and obtained multiple issued patents covering the accused
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`technology.
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`Daiichi Sankyo Japan has continually expended substantial resources and time into
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`developing the accused product in the more than 10 years since Dr. Naito’s first synthesis of DS-
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`8201 in 2011. In late 2015, Daiichi Sankyo Japan initiated a Phase I clinical trial for DS-8201. In
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`November 2016, the FDA granted Fast Track Designation to DS-8201 for HER2-positive
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`metastatic breast cancer. In August 2017, Daiichi Sankyo Japan initiated a Phase II clinical trial,
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`and the FDA gave DS-8201 a Breakthrough Therapy Designation. On March 29, 2019, Daiichi
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`Sankyo Japan and AstraZeneca announced a global development and commercialization
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`collaboration for DS-8201, worth up to $6.9 billion.
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` on December 20, 2019, the FDA approved DS-8201
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`(Enhertu®) for the treatment of adult patients with unresectable or metastatic HER2-positive breast
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`cancer who have received two or more prior anti-HER2 based regimens. On January 15, 2021,
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`the FDA also approved DS-8201 for the treatment of adult patients with locally advanced or
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`metastatic HER2 positive gastric or gastroesophageal junction (GEJ) adenocarcinoma who have
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`received a prior trastuzumab-based regimen.
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`Daiichi Sankyo Japan has expended significant resources bringing DS-8201 to market,
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`including
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`DS-8201 from 2012 to the filing of the ’839 application
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` on the research, preclinical and clinical studies of
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`.
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`Accordingly, the evidence will establish both elements of prosecution laches, and Seagen’s
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`claim is therefore barred.
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`V.
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`THE ’039 PATENT CLAIMS ARE INVALID UNDER 35 U.S.C. § 112(b)
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`Daiichi Sankyo Japan will present evidence and argument establishing that the ’039 patent
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`claims fail the first required element of 35 U.S.C. § 112(b)—they fail to set forth what the
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`applicants regard as their invention—and so the claims are invalid.
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`In identifying the drug moiety attached to antibodies in the alleged invention, the ’039
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`patent’s specification describes only monomethylvaline compounds (also known as auristatin
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`compounds, MMAE and MMAF in particular). (See, e.g., DX-0001 at 1 (patent title is
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`“Monomethylvaline Compounds Capable of Conjugation to Ligands,” abstract describes
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`“Auristatin peptides, including [MMAE] and [MMAF], were prepared and attached to Ligands
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`through various linkers”), 82 (describing the drug moiety of the ADC as being “of the
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`dolastatin/auristatin type”).)
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`Dr. Lambert confirmed this point in his testimony during the jury trial in this action. (Dkt.
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`376, Trial Tr. (Day 3) at 108:3-10.) It is also consistent with the testimony of the named inventors
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`on the ’039 patent presented at the jury trial. For example, Seagen’s Dr. Senter acknowledged the
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`’039 patent’s title is “Monomethylvaline Compounds Capable of Conjugation to Ligands” and that
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`the accused product is not and does not include a monomethylvaline compound, (Dkt. 374, Trial
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`Tr. (Day 1) at 245:13-25), and admitted that all of the claims of the original patent in the ’039
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`patent family referred to auristatin-type structures and that the accused product is not an auristatin-
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`type structure, (id. at 252:4-21). Dr. Senter also admitted that the ’839 application (which led to
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`the ’039 patent) was the first time the drug moiety was not limited to an auristatin or dolastatin
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`analog, that the claim wording changed, and that he was not included in the decision to make that
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`change in the claim language (despite being a named inventor). (Id. at 260:16-261:5.) Similarly,
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`Seagen’s Dr. Toki admitted what was new in his patents, i.e., what the invention was, was MMAE
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`and MMAF (i.e., the auristatin-based drug moieties). (Dkt. 377, Trial Tr. (Day 4) at 64:9-12.)
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`The ’039 patent claims, however, are not limited to auristatin- or dolastatin-based drug
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`moieties like the other members of the patent family. They reach broader and purport to
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`encompass drug moieties not described in the specification, including camptothecins (the drug
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`moiety of Enhertu®) and, indeed, any drug moiety. (See DX-0001 at 212 (independent claim 1
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`depicting an ADC structure including “D,” where “D is a drug moiety”); see also Dkt. 376, Trial
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`Tr. (Day 3) at 111:9-112:5.)
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`Accordingly, because the ’039 patent claims (encompassing any drug moieties) reach much
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`broader than the specification (limited to drug moieties with monomethylvaline compounds), the
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`claims are contradictory to the specification, and so the ’039 patent fails to set forth what is
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`regarded by the applicants as the purported invention. The ’039 patent’s claims are thus invalid.
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`Allen, 299 F.3d at 1349.
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`VI. CONCLUSION
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`In light of the foregoing, and the evidence and argument to be offered at the bench trial in
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`this action, Daiichi Sankyo Japan respectfully requests this Court finds that Seagen’s claim is
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`barred by prosecution laches and/or 35 U.S.C. § 112(b).
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`Case 2:20-cv-00337-JRG Document 429 Filed 07/14/22 Page 12 of 13 PageID #: 16411
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`Dated: June 20, 2022
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`Respectfully submitted,
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`/s/ Preston K. Ratliff II
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`Deron R. Dacus
`State Bar No. 00790553
`The Dacus Firm, P.C.
`821 ESE Loop 323, Suite 430
`Tyler, Texas, 75701
`+1 (903) 705-1117
`+1 (903) 581-2543 facsimile
`ddacus@dacusfirm.com
`
`J. Mark Mann
`State Bar No. 12926150
`mark@themannfirm.com
`MANN | TINDEL | THOMPSON
`300 West Main Street
`Henderson, Texas 75652
`(903) 657-8540
`(903) 657-6003 (fax)
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`Attorneys for Defendant Daiichi Sankyo Company,
`Limited
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`OF COUNSEL:
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`Preston K. Ratliff II
`Ashley N. Mays-Williams
`Paul Hastings LLP
`200 Park Avenue
`New York, NY 10166
`(212) 318-6000
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`Jeffrey A. Pade
`Paul Hastings LLP
`2050 M Street NW
`Washington, DC 20036
`(202) 551-1700
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`Attorneys for Defendant Daiichi Sankyo Company,
`Limited
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`CERTIFICATE OF SERVICE
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`The undersigned hereby certifies that all counsel of record who have consented to
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`electronic service are being served with a copy of this document via electronic mail on June 20,
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`2022.
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`/s/ Preston K. Ratliff II
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