DCT

1:22-cv-01484

Pfizer Inc v. SinoTherap Inc

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:22-cv-01484, D. Del., 01/30/2023
  • Venue Allegations: Venue is alleged to be proper as Defendant is a foreign corporation, which may be sued in any judicial district.
  • Core Dispute: Plaintiff alleges that Defendant’s submission of a supplement to an Abbreviated New Drug Application (ANDA) to market generic versions of Plaintiff's Xeljanz® XR product constitutes an act of infringement of two patents related to sustained-release formulations of tofacitinib.
  • Technical Context: The technology concerns pharmaceutical dosage forms, specifically osmotic tablets designed to provide a once-daily, sustained release of tofacitinib, a Janus kinase (JAK) inhibitor for treating autoimmune disorders.
  • Key Procedural History: This action was initiated under the Hatch-Waxman Act following Defendant’s notification to Plaintiff of its filing of a supplement to ANDA No. 216001 containing a Paragraph IV certification, alleging the patents-in-suit are invalid, unenforceable, or will not be infringed. The patents-in-suit are listed in the U.S. Food and Drug Administration's "Orange Book" for Plaintiff's Xeljanz XR product.

Case Timeline

Date Event
2013-03-16 '309 and '523 Patents - Earliest Priority Date
2020-05-05 '309 Patent - Issue Date
2022-02-22 '523 Patent - Issue Date
2022-09-26 Defendant's ANDA Supplemental Notice Letter
2023-01-30 Amended Complaint Filing Date

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 10,639,309 - Tofacitinib Oral Sustained Release Dosage Forms

  • Patent Identification: U.S. Patent No. 10,639,309, "Tofacitinib Oral Sustained Release Dosage Forms," issued May 5, 2020 (Compl. ¶22).
  • The Invention Explained:
    • Problem Addressed: The patent describes the need for a once-daily (QD) formulation of tofacitinib to improve patient convenience and compliance compared to the existing twice-daily (BID) immediate-release tablet (Compl. ¶22; ’309 Patent, col. 3:25-29). The inventors noted that simply prolonging the drug's release duration could surprisingly reduce its bioavailability, and that an optimal profile required maintaining a "drug holiday"—a period where plasma concentration falls below a certain therapeutic threshold—to avoid over-inhibition of the immune system (’309 Patent, col. 3:1-5, 42-68).
    • The Patented Solution: The invention is an oral sustained-release dosage form, specifically an osmotic tablet, that is engineered to provide a specific pharmacokinetic profile. This profile balances total drug exposure (AUC) with controlled peak (Cmax) and trough (Cmin) concentrations to achieve a once-daily therapeutic effect comparable to the twice-daily tablet while preserving the necessary "drug holiday" (’309 Patent, Abstract; col. 4:1-20). The patent discloses osmotic delivery systems as a means to achieve this controlled release (’309 Patent, col. 5:40-49).
    • Technical Importance: The formulation aims to provide the clinical benefits of once-daily dosing without compromising the specific pharmacokinetic balance of efficacy and safety required for a JAK inhibitor like tofacitinib (’309 Patent, col. 3:25-41).
  • Key Claims at a Glance:
    • The complaint asserts independent claim 1 (Compl. ¶41).
    • Claim 1 requires:
      • A once-daily pharmaceutical dosage form.
      • A core comprising 22 mg of tofacitinib (or an equivalent salt) and an osmagen.
      • A semi-permeable membrane coating surrounding the core, which comprises a water-insoluble polymer.
      • A specific in vitro dissolution profile when tested in a standard USP apparatus: not more than 30% dissolved in 1 hour; 35-75% dissolved in 2.5 hours; and not less than 75% dissolved in 5 hours.
      • Delivery of tofacitinib "primarily by osmotic pressure."
      • The water-insoluble polymer being a cellulose derivative.
    • The complaint does not explicitly reserve the right to assert dependent claims.

U.S. Patent No. 11,253,523 - Tofacitinib Oral Sustained Release Dosage Forms

  • Patent Identification: U.S. Patent No. 11,253,523, "Tofacitinib Oral Sustained Release Dosage Forms," issued February 22, 2022 (Compl. ¶27).
  • The Invention Explained:
    • Problem Addressed: As a continuation of the application leading to the ’309 Patent, this patent addresses the same technical problem: creating an optimized once-daily tofacitinib formulation that improves patient convenience while maintaining a specific, beneficial pharmacokinetic profile and "drug holiday" (’523 Patent, col. 3:45-68).
    • The Patented Solution: The invention claims methods of treating immunological disorders by administering the specific tofacitinib sustained-release dosage forms. The claims cover formulations characterized by their dosage strength, their in vitro dissolution profile, and/or their resulting in vivo pharmacokinetic parameters (AUC and Cmax/Cmin ratio) when delivered via an osmotic system (’523 Patent, Abstract; col. 4:25-44).
    • Technical Importance: The claims protect the specific use of these engineered formulations to treat diseases like rheumatoid arthritis, tying the novel dosage form directly to its therapeutic application (’523 Patent, col. 7:1-9).
  • Key Claims at a Glance:
    • The complaint asserts independent claims 1 and 50 (Compl. ¶¶48, 62).
    • Claim 1 requires:
      • A method of treating a specified immunological disorder.
      • Administering a once-daily dosage form with a core comprising 11 mg of tofacitinib and an osmagen.
      • The core is surrounded by a semi-permeable membrane coating.
      • The dosage form has the specific in vitro dissolution profile also recited in claim 1 of the ’309 patent.
      • Delivery occurs "primarily by osmotic pressure."
    • Claim 50 requires:
      • A method of treating a specified immunological disorder.
      • Administering a once-daily dosage form with a core comprising 22 mg of tofacitinib and an osmagen.
      • The core is surrounded by a semi-permeable membrane coating.
      • When administered, the form provides a specific in vivo pharmacokinetic profile: an AUC in the range of 80% to 125% of a 10 mg immediate-release BID dose and a ratio of geometric mean plasma Cmax to Cmin from about 10 to 100.
      • Delivery occurs "primarily by osmotic pressure."
    • The complaint does not explicitly reserve the right to assert dependent claims.

III. The Accused Instrumentality

Product Identification

  • "Sinotherapeutics Generic 11 mg XR Tablets" and "Sinotherapeutics Generic 22 mg XR Tablets" (collectively, "Sinotherapeutics Generic XR Tablets") (Compl. ¶2).

Functionality and Market Context

  • The accused products are described as "Extended-Release tablet[s]" containing either 11 mg or 22 mg of tofacitinib citrate (Compl. ¶33). As this suit was triggered by an ANDA filing, the complaint bases its allegations on the contents of that application, which seeks approval to market these products as generic copies of Pfizer’s Xeljanz® XR before the expiration of the patents-in-suit (Compl. ¶2, ¶34). The complaint alleges that upon approval, Sinotherapeutics intends to commercialize, manufacture, and sell these products in the United States (Compl. ¶39, ¶43, ¶50, ¶64).

IV. Analysis of Infringement Allegations

The complaint does not provide sufficient detail for a claim-chart analysis. It alleges infringement based on Defendant's filing of a supplement to ANDA No. 216001, which seeks approval to market generic versions of Pfizer's Xeljanz® XR product (Compl. ¶41, ¶48, ¶62). The theory of infringement is that the product described in the ANDA, if approved and marketed, will meet all limitations of the asserted claims.

No probative visual evidence provided in complaint.

  • Identified Points of Contention:
    • Scope Questions: A central dispute may be whether Sinotherapeutics' formulation, by virtue of being designed as bioequivalent to Xeljanz® XR, necessarily practices the claimed invention. This raises the question of whether the specific in vitro dissolution profiles claimed in the ’309 Patent and claim 1 of the ’523 Patent are inherent properties of any bioequivalent formulation, or if bioequivalence could be achieved via a formulation with a different dissolution profile. Similarly, for claim 50 of the ’523 Patent, a question is whether the bioequivalence data in the ANDA will establish that the product meets the specific in vivo AUC and Cmax/Cmin ratio limitations.
    • Technical Questions: The technical mechanism of release will likely be a key point of contention. The court will have to determine what evidence the ANDA provides that the accused product achieves sustained release "primarily by osmotic pressure" as required by all asserted claims, versus another mechanism such as matrix erosion or simple diffusion.

V. Key Claim Terms for Construction

  • The Term: "delivers the tofacitinib... primarily by osmotic pressure" (’309 Patent, claim 1; ’523 Patent, claims 1, 50).

    • Context and Importance: This term defines the core release mechanism of the claimed invention. The infringement analysis for all asserted claims will depend on whether the accused product employs this specific mechanism. Practitioners may focus on this term because if Defendant’s product achieves extended release through a different principal mechanism, it may fall outside the claim scope.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The specification discusses sustained release dosage forms generally before focusing on osmotic systems, which could suggest that "primarily" does not require osmotic pressure to be the sole or exclusive force, but merely the most significant contributor to release (’309 Patent, col. 3:25-36).
      • Evidence for a Narrower Interpretation: The detailed description of the invention heavily emphasizes and provides detailed examples of specific osmotic delivery systems, including "an extrudable core system, swellable core system, or asymmetric membrane technology" (’309 Patent, col. 5:40-52). A party might argue that the term "primarily by osmotic pressure" should be construed in light of these specific embodiments, limiting it to dosage forms that operate in a substantially similar way.

  • The Term: The specific numerical ranges of the dissolution profile (e.g., "dissolves not more than 30% of the tofacitinib... in 1 hour") (’309 Patent, claim 1; ’523 Patent, claim 1).

    • Context and Importance: These are precise, quantitative limitations central to defining the invention's controlled-release characteristics. Infringement will require testing the accused product under the specified conditions and comparing the results to these claimed boundaries.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: A party could argue that standard experimental variability is inherent in such measurements, suggesting the numbers should not be read as absolute mathematical limits but should encompass minor deviations. However, the claims do not use modifiers like "about."
      • Evidence for a Narrower Interpretation: The patent provides specific examples with dissolution data that fall within the claimed ranges (’309 Patent, col. 48, Table 4). The absence of "about" or similar qualifying language in the claim itself suggests the patentee intended to be bound by the recited numerical limits.

VI. Other Allegations

  • Indirect Infringement: The complaint alleges induced and contributory infringement of the method claims of the ’523 Patent. It asserts that Defendant intends for its products to be used for the same therapeutic indications as Xeljanz® XR, and that its proposed labeling will instruct physicians and patients to administer the generic drug in a manner that directly infringes the patented methods (Compl. ¶51-54, ¶65-68). The complaint also alleges the product has no substantial non-infringing uses (Compl. ¶56, ¶70).
  • Willful Infringement: The complaint does not contain a separate count for willful infringement. However, it alleges that Defendant had knowledge of the patents-in-suit at the time it submitted its ANDA supplement, which could form the basis for a future claim of willfulness or a request for enhanced damages (Compl. ¶42, ¶49, ¶63).

VII. Analyst’s Conclusion: Key Questions for the Case

  • A core issue will be one of bioequivalence versus infringement: does Sinotherapeutics’ product, by demonstrating bioequivalence to Xeljanz® XR as required by its ANDA, necessarily meet the specific in vitro dissolution and in vivo pharmacokinetic limitations recited in Pfizer’s asserted claims, or is it possible to be bioequivalent without literally infringing?
  • A central claim construction and factual question will be one of mechanism: does the accused generic tablet achieve its sustained-release profile "primarily by osmotic pressure," as narrowly defined by the patent's embodiments, or does it rely on a different technical mechanism that places it outside the scope of the claims?