Mylan Pharmaceuticals Inc. v. Merck Sharp & Dohme Corp.

I'll research this case and its underlying litigation before drafting.

Good — I have the core PTAB record. Now let me verify the Federal Circuit appeals, the district court outcome, the Teva joinder, and the commercial/market context.

Important framing correction: IPR2020-00040 is not a patent-infringement lawsuit — it is an inter partes review at the PTAB, i.e., an administrative validity trial in which Mylan, as petitioner, asked the Board to cancel claims of Merck's patent. The infringement litigation is the parallel Hatch-Waxman action, Merck Sharp & Dohme Corp. v. Mylan Pharmaceuticals Inc., No. 1:19-cv-00101-IMK (N.D. W. Va.), which this IPR was filed to defend against.

Parties and the real-world dispute. Mylan Pharmaceuticals Inc. (Morgantown, W. Va.; the U.S. generic arm of Mylan N.V., now Viatris; Mylan Inc. and Mylan N.V. were named real parties-in-interest in the petition) is a generic drug manufacturer. Merck Sharp & Dohme Corp. — a Merck & Co. subsidiary that, effective May 1, 2022, merged into Merck Sharp & Dohme, LLC — is the innovator operating company that owns the patent and markets the branded products. The IPR is one front in a broader generic-vs.-innovator campaign: EPA/Orange Book–listed the sitagliptin patents, Merck filed Hatch-Waxman suits against roughly fourteen generic filers (Mylan, Teva, Watson, Apotex, Sandoz, Zydus, Sun, Lupin, Torrent, Wockhardt, Alvogen, Anchen, Macleods, Accord, Par), which were centralized for pretrial proceedings as In re Sitagliptin Phosphate ('708 & '921) Patent Litigation, No. 19-md-2902-RGA (D. Del.) before Judge Richard G. Andrews (claim construction at 2020 WL 6743022 (D. Del. Nov. 17, 2020)); the Mylan action itself was filed May 2, 2019 in the Northern District of West Virginia, Clarksburg Division, before Judge Irene M. Keeley (venue anchored on Mylan's West Virginia ANDA filer/place of business), and was tried there rather than in Delaware. Sources: N.D. W. Va. Dkt. 204 (opinion); IPR2020-01060 petition, related-matters section.

Accused products and the patents. The accused products are Mylan's generic versions of Merck's Januvia® (sitagliptin) and Janumet® (sitagliptin + metformin), ANDA Nos. 202473 and 202478. The IPR targets U.S. Patent No. 7,326,708 ("Phosphoric acid salt of a dipeptidyl peptidase-IV inhibitor"), which claims the dihydrogenphosphate ("DHP") salt of sitagliptin — sitagliptin DHP — in a 1:1 phosphate:amine stoichiometry (claim 1), the (R)- and (S)-enantiomers (claims 2–3), a crystalline monohydrate of the (R) form (claim 4/24), pharmaceutical compositions (claim 17), a method of treating Type 2 diabetes (claim 19), and process/product-by-process claims (claims 21–23); sitagliptin is the DPP-4 inhibitor that is the active moiety of Januvia/Janumet. Mylan challenged claims 1–4, 17, 19, and 21–23, asserting anticipation by Merck's own earlier WO 2003/004498/’871 patent ("Edmondson") plus obviousness over Edmondson with Brittain (pharmaceutical hydrates) and Bastin (salt selection). In the district court case Merck narrowed to claim 3 of the ’708 patent and claim 1 of the related formulation patent U.S. Pat. No. 8,414,921 (the ’921 patent expires July 21, 2028; Jan. 21, 2029 with pediatric exclusivity); Mylan stipulated to infringement of ’708 claims 1, 2 and 19 (Dec. 10, 2021 stipulation, Dkt. 152) and lost after a five-day bench trial — judgment for Merck entered Sept. 21, 2022 (Dkt. 194) and opinion at Dkt. 204 rejecting Mylan's obviousness-type double patenting and § 112 written-description/enablement attacks.

Posture, panel, and why it matters. The PTAB panel — APJs Sheridan K. Snedden, Robert A. Pollock, and Timothy G. Majors — instituted on all grounds May 12, 2020 (Paper 21) over Merck's § 325(d)/§ 314(a) discretionary arguments, and issued a Final Written Decision May 7, 2021 holding no challenged claim unpatentable (2021 WL 1833325), also denying Merck's motion to exclude. The proceeding became a joinder hub for "me-too" petitioners: Teva/Watson (IPR2020-01045, joined Sept. 1, 2020, then terminated Dec. 8, 2020 after settlement and withdrawn Dec. 15, 2020), Dr. Reddy's (IPR2020-01060), and Sun (IPR2020-01072), each joining as a "silent understudy" bound by Mylan's papers and expert. On appeal, the Federal Circuit affirmed in a precedential opinion, Mylan Pharms. Inc. v. Merck Sharp & Dohme Corp., No. 2021-2121 (Fed. Cir. Sept. 29, 2022) (Lourie, Reyna, Stoll, JJ.), opinion PDF. The case is notable doctrinally and commercially: (1) it is a leading application of In re Petering's "at once envisage" test to chemistry — the Federal Circuit held that a genus of ~957 predicted salts (33 compounds × 8 preferred acids × stoichiometries), some of which may not form at all, is too large to anticipate a species, and it expressly declined to give a numeric definition of a "limited class"; (2) it illustrates inherency limits for salt/polymorph patents, with the Board finding 1:1 sitagliptin DHP does not form "every time"; (3) it turns on rarely litigated pre-AIA mechanics — Merck antedated Edmondson by reducing 1:1 (R)-sitagliptin DHP to practice in Dec. 2001/early 200

I'll research this case, noting upfront that the "case" in the metadata is an IPR at the PTAB — so I'll cover both the PTAB proceeding and the underlying district court litigation on U.S. Patent 7,326,708.

Now let me dig into the underlying district court litigation and the MDL, plus the appeal.

Let me get more detail on the N.D. W. Va. case docket, the stay motion, and the appeals.

I'll research the counsel of record for the petitioner (plaintiff) in this IPR.

Good initial data. Let me nail down the petitioner's mandatory notices and any updates during the proceeding.

Let me confirm the initial mandatory notice and the Federal Circuit appeal counsel for Mylan.

Threshold point on framing

This is not a district-court patent infringement action, so there is no PACER docket and no "plaintiff" in the Rule 3 sense. IPR2020-00040 is an inter partes review at the PTAB; the party on the plaintiff side is the petitioner, Mylan Pharmaceuticals Inc. Its counsel appear via the mandatory notices under 37 C.F.R. § 42.8(b)(3) (the PTAB analogue of a Rule 11/7.1 appearance), on the USPTO's PTAB E2E / P-TACTS system rather than PACER. The parallel infringement suits (e.g., Merck Sharp & Dohme Corp. v. Mylan Pharms. Inc., No. 1:19-cv-00101-IMK (N.D. W. Va.); the Delaware sitagliptin MDL, No. 1:19-md-02902-RGA) are separate proceedings in which Mylan is the defendant, not the plaintiff. Below I identify counsel of record for the petitioner Mylan in the IPR.

Also note the IPR had joined petitioners — Dr. Reddy's (IPR2020-01060), Sun (IPR2020-01072), and Teva/Watson (IPR2020-01045, later settled and terminated). Mylan remained Lead Petitioner responsible for all substantive filings; the joiners agreed not to file merits papers (June 26, 2020 correspondence, cited in IPR2020-01072 Ex. 2035).

Counsel of record for Petitioner Mylan Pharmaceuticals Inc. — Katten Muchin Rosenman LLP

Per Petitioner's Updated Mandatory Notice, Paper 48 (Sept. 17, 2020) and the parties' Joint Notice of Stipulation to Adjust Schedule, Paper 37 (Aug. 7, 2020):

Source: Petitioner's Updated Mandatory Notice, IPR2020-00040 Paper 48 (P.T.A.B. Sept. 17, 2020) — states that Lance A. Soderstrom was added as backup counsel and that there were "no other changes to Lead and Backup Counsel or service information"; the pre-existing roster (Malik lead; Pacchioli, Radeke, West backup) is confirmed in the Aug. 7, 2020 joint stipulation (Paper 37).

Additional Katten attorney tied to Mylan's related matters (appearance in the IPR not confirmed)

• Deepro R. Mukerjee — Katten, New York, NY; global chair of Katten's IP practice. He is listed as Mylan's admitted pro hac vice counsel in the parallel N.D. W. Va. litigation (No. 1:19-cv-00101, e.g., Dec. 10, 2021 stipulation) and led Katten's Mylan trial team in 2024. I could not confirm that he was formally designated as counsel of record in the IPR2020-00040 mandatory notices; treat his IPR appearance as unverified. (Likewise, the individual notices I retrieved did not name him, so I am not asserting it.)

In-house counsel

None identified. Mylan's in-house attorneys did not appear as counsel of record in the PTAB mandatory notices retrieved. If Mylan had in-house counsel involved, they were not designated of record in this proceeding (or the designation is not in the public documents I could access).

Joined petitioners' counsel (co-petitioners, not Mylan)

For completeness — these firms represented the joined petitioners, not the lead petitioner:

• Dr. Reddy's Laboratories (IPR2020-01060): Lerner David Littenberg Krumholz & Mentlik LLP — Russell W. Faegenburg, Tedd W. Van Buskirk, Michael H. Teschner (emails in IPR2020-01072 exhibits).
• Sun Pharmaceutical Industries (IPR2020-01072): Goodwin Procter LLP — Sarah Fischer and Keith A. Zullow (goodwinlaw.com email addresses in the June–July 2020 correspondence).
• Teva/Watson (IPR2020-01045): counsel not captured; that proceeding settled and was terminated, and the Teva parties were disjoined (IPR2020-00040 Paper 73).

⚠️ Caution: do not conflate Sarah Fischer (Goodwin Procter — Sun) with Stanley E. Fisher (Williams & Connolly — Merck's patent-owner lead counsel); both appear in the same correspondence.

Appeal (context)

Mylan appealed the Final Written Decision to the Federal Circuit (Mylan Pharms. Inc. v. Merck Sharp & Dohme Corp., No. 2021-2121 (Fed. Cir. Sept. 29, 2022), which affirmed the Board's no-unpatentability holding). My searches did not retrieve the Federal Circuit briefs, so I cannot confirm Mylan's appellate counsel of record and will not guess.

Sourcing / limitations

• Primary: PTAB papers and exhibits (Petitioner's Updated Mandatory Notice, Paper 48; Joint Stipulation/Notice, Paper 37; Patent Owner mandatory notices, Papers 5, 29, 33; the May 7, 2021 Final Written Decision). Available via USPTO PTAB E2E / P-TACTS and mirrored on Docket Alarm and free-law aggregators.
• Nothing indicates the counsel-appearance filings here were sealed.
• The IPR's "plaintiff" is the petitioner (Mylan); for the actual infringement litigation over the '708 patent, Mylan is the defendant. If your question is aimed at the N.D. W. Va. or Delaware infringement cases instead, say so and I can pull that docket (there, Mylan's defense counsel likewise include Katten's Malik, Pacchioli, Mukerjee, Soderstrom, and Joseph M. Janusz).

I'll research the counsel of record for the patent owner (Merck), who is the "defendant" in this IPR, using the PTAB docket and related sources.

I have strong primary-source material. Let me confirm the full counsel list from the mandatory notices and gather firm/bio details.

Preliminary note on the record and the parties' alignment

A threshold clarification, because it affects who the "defendant" is: IPR2020-00040 is not a district-court infringement suit — it is an inter partes review before the PTAB. In the IPR, the alignment is Mylan Pharmaceuticals Inc. (Petitioner) v. Merck Sharp & Dohme Corp. (Patent Owner). The party in the defensive/responding posture — the functional "defendant," and the real party defending the validity of U.S. Patent 7,326,708 — is Merck Sharp & Dohme Corp., a wholly owned subsidiary of Merck & Co., Inc. (Pet. 6; Power of Attorney, Paper 6). The parallel Hatch-Waxman infringement actions (including the consolidated MDL, In re Sitagliptin Phosphate ('708 & '921) Patent Litig., No. 19-md-2902-RGA (D. Del.)) are separate proceedings.

So the counsel below is Merck's PTAB team, drawn entirely from Williams & Connolly LLP (Washington, D.C.), plus Merck in-house. The list is grounded in Merck's Power of Attorney (Paper 6, Nov. 18, 2019), its Second and Fourth Amended Mandatory Notices (Papers 29 and 59), the signature blocks on the substantive filings, and the Final Written Decision of May 7, 2021.

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Lead counsel

Backup counsel of record (Williams & Connolly LLP)

In-house counsel

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Separate: appellate counsel (Federal Circuit No. 2021-2121) — not PTAB counsel of record

On Mylan's appeal of the FWD, Merck's team was expanded with appellate specialists. These attorneys did not appear on the IPR docket:

• Jeffrey A. Lamken — counsel of record on appeal, MoloLamken LLP, Washington, D.C. (argued the appeal)
• Michael G. Pattillo, Jr. and Caleb Hayes-Deats — MoloLamken LLP, Washington, D.C.
• Mark W. Kelley and Lauren F. Dayton — MoloLamken LLP, New York
• Charles L. McCloud — Williams & Connolly LLP (appellate brief only)

(Source: Fed. Cir. No. 2021-2121, Corrected Response, Doc. 64, Jan. 19, 2023; Fed. Cir. opinion, 50 F.4th 147 (Sept. 29, 2022).)

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Caveats and sourcing notes

• All Williams & Connolly attorneys above are in the firm's Washington, D.C. office (725 Twelfth Street, N.W. during the IPR; the firm has since relocated to 680 Maine Ave. SW). The firm was the sole outside counsel for Merck on this IPR; there was no separate "local counsel" because the PTAB sits in Alexandria, VA and does not require local admission.
• Pro hac vice designations: Genderson, Zolan, and Baumgarten were admitted pro hac vice (noted "Pro Hac Vice" in the mandatory notices), i.e., they are not registered patent practitioners; Fisher, Berniker, Krinsky, Mahaffy, and Sheh are USPTO-registered.
• The Board's own caption for the Final Written Decision names only Fisher, Berniker, Mahaffy, and Sheh, but the operative counsel-of-record list is the one in the Fourth Amended Mandatory Notices (Paper 59) signed by Fisher, Genderson, Krinsky, Baumgarten, Zolan, Mahaffy, and Sheh.
• Additional W&C personnel (e.g., Jingyuan Luo, Sarahi Uribe, Vanessa Omoroghomwan, Jihad Komis) appear in firm/team listings and the Federal Circuit certificate of interest as members of the broader Merck sitagliptin matter, but I did not find them designated as counsel of record on the IPR2020-00040 docket, so I have not listed them as such.
• Not sealed: the identities of counsel are not sealed here — the mandatory notices, power of attorney, and FWD are public PTAB records.
• For completeness, the joined petitioners' counsel (not the "defendant") were Katten Muchin Rosenman (Mylan), Lerner David (Dr. Reddy's), Winston & Strawn (Sun), and Goodwin Procter (Teva/Watson) — identified only to make clear they represent the petitioner side, not Merck.