In re Sitagliptin Phosphate ('708 & '921) Patent Litigation

I'll research this case to build out the case overview and background.

Case Overview and Background

Parties. This is a brand-versus-generics Hatch-Waxman MDL, not an NPE/PAE assertion. The sole plaintiff is Merck Sharp & Dohme Corp. (subsequently substituted as Merck Sharp & Dohme LLC), the operating pharmaceutical company that markets the branded DPP-IV inhibitor franchise. The defendants are generic drug manufacturers — per the JPML transfer order, 23 defendants organized into 13 corporate groups, including Alvogen Pine Brook/Alvogen Malta, Anchen/Par Pharmaceutical, Sandoz, Apotex, Zydus/Cadila Healthcare, Macleods, Watson/Teva, Sun Pharma, Torrent, Wockhardt, Lupin, and Mylan (now part of Viatris), with later-added parties such as Biocon, Accord, and Dr. Reddy's appearing in the docket. Merck is represented by Williams & Connolly (Genderson, Fisher, Zolan, Baumgarten, Berniker, Luo, Sheh, Mahaffey) with McCarter & English (Kelly, Silver, Joyce) as Delaware counsel; defense-side lead firms of record include Goodwin Procter (Sandoz/Teva/Watson), Knobbe Martens (Lupin), Katten Muchin/Locke Lord (Apotex/Zydus), Axinn Veltrop & Harkrider (Par/Anchen), and Winston & Strawn (Sun). See J.P.M.L. transfer order, MDL No. 2902; Memorandum Opinion, Nov. 17, 2020.

Accused products and patents. The accused conduct is the filing of 26 ANDAs (14 actions originally) seeking FDA approval to market generic sitagliptin phosphate — i.e., generic versions of Merck's Januvia, Janumet (sitagliptin + metformin HCl), and Janumet XR — with paragraph IV certifications. Merck asserted infringement under 35 U.S.C. § 271(e)(2), plus inducement/contributory infringement theories. Two patents are in suit: U.S. Pat. No. 7,326,708 ("the '708 patent"), which claims the 1:1 dihydrogenphosphate (DHP) salt of sitagliptin and its crystalline monohydrate form, plus a crystallization process — the so-called "salt/polymorph patent," expiring Nov. 24, 2026 with pediatric exclusivity to May 24, 2027; and U.S. Pat. No. 8,414,921 ("the '921 patent"), which claims pharmaceutical compositions combining sitagliptin (or its salt) with metformin hydrochloride and a surfactant, expiring Jan. 21, 2029 with pediatric exclusivity to July 21, 2029. Merck's own characterization in SEC filings is that the '708 salt patent is the gating patent that "would preclude generic manufacturers from making sitagliptin phosphate salt and polymorphic forms" until 2027.

Procedural posture and venue. MDL No. 2902 was created by the JPML on August 8, 2019, centralizing 13 District of Delaware actions and one N.D. W. Va. action (Merck v. Mylan) before Judge Richard G. Andrews in the District of Delaware, Wilmington. The Panel chose Delaware because 13 of the 14 actions were already pending there and Judge Andrews was "well-versed in complex patent litigation." Claim construction issued November 17, 2020 (D.I. 135 in C.A. No. 19-311-RGA) after Aug. 18, 2020 argument, construing terms in the '708 patent ("the salt of claim 1," "crystalline monohydrate," XRPD "characteristic absorption bands," crystallization at 25°C) and the '921 patent ("surfactant," "sitagliptin," "sodium lauryl sulfate," "sitagliptin phosphate monohydrate"). The court had scheduled a consolidated three-day trial on invalidity in October 2021 and one-day infringement trials thereafter, but the record indicates most defendants resolved their cases by consent judgment (e.g., DRL, Apotex, Sandoz in September–October 2021), and the MDL was reported as terminated by the JPML on February 27, 2023. Per Merck's disclosures, the MDL spawned a parallel PTAB track — IPR2020-00040 (Mylan v. Merck), instituted May 12, 2020 on claims 1–4, 17, 19, 21–23 of the '708 patent, with Teva (IPR2020-01045), DRL (IPR2020-01060), and Sun (IPR2020-01072) joining. The Board's May 7, 2021 final written decision found no challenged claims unpatentable, and the Federal Circuit affirmed on September 29, 2022, in Mylan Pharms. Inc. v. Merck Sharp & Dohme Corp., No. 2021-2121 (Lourie, J.). Notably, in the non-MDL West Virginia case, Judge Keeley conducted a five-day bench trial and issued a sealed memorandum opinion on October 26, 2022 (D.I. 204) finding claim 3 of the '708 patent and claim 1 of the '921 patent valid and infringed; that case settled on remand in spring 2023.

Why it matters. (1) Market stakes: Januvia and Janumet together were Merck's third-best-selling franchise (~$5.3 billion in 2021 sales); the '708 patent is what carries U.S. exclusivity past the January 2023 loss of base protection, and Merck has stated it entered 21+ settlements permitting generic entry in May 2026 for Januvia/Janumet and July 2026 for Janumet XR, "or earlier under certain circumstances" (note: a Merck 10-Q covering Q1 2021 stated May 2027/July 2026 entry dates — a discrepancy I could not resolve from a primary source). (2) IPR linkage: the case is an example of generic defendants running district-court invalidity in parallel with joined IPRs; the footnote in Judge Andrews's claim construction opinion expressly notes that Mylan, "due to the pending IPR in connection with the '708 patent," declined to join any of the defendants' proposed constructions — a concrete illustration of IPR-driven divergence among co-defendants. (3) Federal Circuit law: the appeal produced a published-looking ruling on the In re Petering "at once envisage" doctrine, holding that a genus of 957 possible salts derived from 33 compounds and eight "particularly preferred" acids is too broad to anticipate — a decision that drew a notable dissent-in-spirit cert petition arguing the panel added a "direction to select" requirement to § 102 (I have not verified the cert petition's disposition). (4) Venue: D. Del. functions here as the national clearinghouse for Hatch-Waxman ANDA litigation, consolidating a dozen-plus separate defendant groups under one claim construction and one validity trial. Sourcing caveat: docket-level details beyond the cited opinions (e.g., the precise count of consent judgments, the final MDL termination order, and the terms of individual settlements, which are typically confidential) are drawn from the JPML statistics report, Merck press releases/SEC filings, and third-party docket aggregators rather than PACER directly and should be confirmed before being relied on as verbatim record facts.

I'll research the docket-level chronology, rulings, and parallel proceedings to build this section.

Good detail emerging. Let me dig into the docket chronology, motions practice, and the PTAB/appeal tracks.

Key Legal Developments and Outcome

Below is a docket-anchored chronology. Where a fact comes only from a secondary aggregator rather than a primary document, I say so. Builds on the overview above; where I found a conflict with that overview I flag it.

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I. Pre-MDL filing phase (Feb.–Aug. 2019)

I'll research plaintiff-side counsel of record for MDL No. 2902 and the constituent Delaware actions.

Good initial data. Let me pull the full plaintiff representation block from the MDL docket and verify each attorney's role and background.

Now let me confirm the full appearance list, the N.D. W. Va. local counsel, and any later-added plaintiff attorneys.

Counsel of Record for Plaintiff Merck Sharp & Dohme Corp. (now Merck Sharp & Dohme LLC)

All of the appearances below are drawn from three independent, mutually corroborating records in this MDL: (1) the D. Del. civil docket representation block for C.A. No. 1:19-md-02902-RGA (captured as an exhibit to the parallel IPR papers and reproduced in the PTAB filings); (2) the counsel line of Judge Andrews's Nov. 17, 2020 memorandum opinion, 1:19-cv-00311-RGA D.I. 135 ("…Fisher (argued), Bruce Genderson, Jingyuan Luo (argued), Williams & Connolly LLP, Washington, DC; Daniel M. Silver, Alexandra M. Joyce, McCarter & English LLP, Wilmington, DE, attorneys for Plaintiff"); and (3) the plaintiff-side signature block of the Apotex consent judgment entered Sept. 29, 2021 in C.A. No. 19-313-RGA. The same team appears in Merck's IPR2020-00040/01045/01060/01072 mandatory notices.

A. Delaware counsel of record — McCarter & English, LLP (Renaissance Centre, 405 N. King St., 8th Fl., Wilmington, DE 19801)

B. Lead merits/patent counsel — Williams & Connolly LLP (725 Twelfth St., N.W., Washington, DC 20005), all appearing pro hac vice in D. Del.

C. West Virginia local counsel (for the transferred Merck v. Mylan action, N.D. W. Va. C.A. No. 1:19-cv-00101-IMK)

• James F. Companion (WV Bar #790) — Schrader Companion Duff & Law, PLLC / Schrader, Byrd & Companion, PLLC, 401 Main St., Wheeling, WV. Signed Merck's memorandum in support of the § 1407 motion expressly "Attorneys for Plaintiff Merck Sharp & Dohme Corp.," and Merck's joint quarterly status reports in the W

I'll research the defense-side counsel of record across the MDL. Let me start with several targeted searches.

Let me pull the full MDL docket sheet and search for per-defendant appearances.

Counsel of Record — Defendants, In re Sitagliptin Phosphate ('708 & '921) Patent Litig., 1:19-md-02902-RGA

Sourcing note up front. The single most reliable roster of defense appearances I could obtain is the caption block of Judge Andrews's claim construction opinion, Memorandum Opinion, D.I. 135, Nov. 17, 2020 (C.A. No. 19-311-RGA) — reproduced at cases.justia.com — which lists participating counsel group-by-group. I supplemented it with the MDL docket sheet (via the PTAB exhibit copy at ptacts.uspto.gov, which embeds the D. Del. docket), the JPML transfer papers, and party-side filings. Where an entry is marked "TERMINATED" on the docket, that reflects a party being dismissed (consent judgment/settlement) rather than a withdrawal. I could not verify counsel for Mylan (the N.D. W. Va. transferor) or for Dr. Reddy's from a primary source in this pass, and I flag those as open items below.

Note the structural point that shapes the entire roster: because this is an MDL in D. Del., every defendant group has a two-tier team — a Delaware firm that satisfies Local Rule 83.5 and does the CM/ECF filing, plus out-of-state "of counsel"/pro hac vice patent counsel who actually try the case. That pattern holds across all 13+ groups.

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By defendant group

1. Alvogen (Alvogen Pine Brook LLC; Alvogen Malta Operations Ltd.) — C.A. No. 19-310

Source: Answer and counterclaims, D. Del. 19-310 (paragraphfour.com copy of dedc19cv0310), listing "OF COUNSEL: Matthew J. Becker… Brett Garrison… /s/ Kelly E. Farnan."

2. Anchen / Par (Anchen Pharmaceuticals, Inc.; Par Pharmaceuticals, Inc.) — C.A. No. 19-311

3. Wockhardt (Wockhardt Bio AG; Wockhardt USA LLC)

Caveat: Wockhardt is not in the Markman caption, which is consistent with that group's earlier exit; I could not pin down the exact termination date.

4. Sandoz / Teva / Watson — C.A. No. 19-312

5. Apotex — C.A. No. 19-313

6. Zydus / Cadila (Zydus Pharmaceuticals (USA) Inc.; Cadila Healthcare Ltd.) — C.A. No. 19-314

7. Macleods (Macleods Pharmaceuticals Ltd.; Macleods Pharma USA, Inc.)

8. Torrent (Torrent Pharmaceuticals Limited; Torrent Pharma Inc.) — C.A. No. 19-320

Source: D. Del. filing in C.A. No. 19-md-2902 (CourtListener recap gov.uscourts.ded.67793.45), signature block: "ABRAMS & BAYLISS LLP … Neal Seth, Laura R. Braden, WILEY, 1776 K Street NW."

9. Lupin (Lupin Limited; Lupin Pharmaceuticals, Inc.) — C.A. No. 19-347