DCT

1:18-cv-01529

Pfizer Inc v. Sun Pharmaceutical Industries Ltd

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Key Events
Complaint

I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:18-cv-01529, D. Del., 10/03/2018
  • Venue Allegations: Venue is alleged to be proper based on the prospective marketing, distribution, and use of the accused generic drug in Delaware following potential FDA approval. The complaint also notes that Defendants have previously consented to jurisdiction and venue in the District of Delaware in other patent actions.
  • Core Dispute: Plaintiff alleges that Defendants' filing of an Abbreviated New Drug Application (ANDA) to market a generic version of Plaintiff's Xeljanz XR® product constitutes an act of patent infringement.
  • Technical Context: The technology concerns oral sustained-release pharmaceutical formulations for tofacitinib, an inhibitor of Janus kinases (JAKs) used for treating conditions such as rheumatoid arthritis.
  • Key Procedural History: The action was initiated under the Hatch-Waxman Act following Defendants' submission of ANDA No. 209790 with a "Paragraph IV" certification. In the certification, Defendants allege that the patent-in-suit is invalid, unenforceable, and/or will not be infringed by their proposed generic product.

Case Timeline

Date Event
2013-03-16 '181 Patent - Earliest Priority Date
2018-04-10 '181 Patent - Issue Date
2018-08-17 Sun Notice Letter Date
2018-08-20 Pfizer receives Sun Notice Letter
2018-10-03 Complaint Filing Date

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

  • Patent Identification: U.S. Patent No. 9,937,181, "Tofacitinib Oral Sustained Release Dosage Forms," issued April 10, 2018.

The Invention Explained

  • Problem Addressed: The patent describes the challenge of creating a once-daily (QD) sustained-release formulation for the drug tofacitinib, which is commercially available as a twice-daily (BID) immediate-release tablet (Compl. ¶17; ’181 Patent, col. 2:5-8). The patent asserts that simply prolonging the drug's release duration can reduce its bioavailability and negatively alter its pharmacokinetic (PK) profile. A specific problem is the potential elimination of a necessary "drug holiday"—a period where plasma concentration falls below a certain threshold—which is believed to be important for the drug's safety profile ('181 Patent, col. 2:45-63).
  • The Patented Solution: The invention is a sustained-release oral dosage form of tofacitinib designed to provide an optimal PK profile for once-daily administration. This is achieved through specific formulations, such as an osmotic pump system, that control the drug release rate to maintain therapeutic efficacy while preserving a drug holiday period comparable to the BID immediate-release version ('181 Patent, col. 3:5-12). The specification details specific dissolution profiles and resulting PK parameters (e.g., AUC, Cmax/Cmin ratio) that characterize the invention ('181 Patent, col. 4:30-40).
  • Technical Importance: The claimed formulation allows for a more convenient once-daily dosing regimen, which may enhance patient compliance while maintaining the established therapeutic and safety profile of the drug ('181 Patent, col. 2:20-25).

Key Claims at a Glance

  • The complaint asserts infringement of at least claim 2 of the ’181 patent (Compl. ¶34). Claim 2 is an independent claim.
  • Essential elements of independent claim 2 include:
    • A once-daily pharmaceutical dosage form comprising a core.
    • The core contains 11 mg of tofacitinib (or an equivalent salt) and an "osmagen."
    • A semi-permeable membrane coating made of a water-insoluble polymer surrounds the core.
    • The dosage form is a sustained release form that, when administered, provides a specific Area Under the Curve (AUC) relative to a 5 mg immediate-release formulation.
    • The dosage form provides a specific ratio of geometric mean maximum plasma concentration (Cmax) to minimum plasma concentration (Cmin) of about 10 to 100.
    • The dosage form delivers the drug "primarily by osmotic pressure."
    • The water-insoluble polymer is a "cellulose derivative" that sustains the release.

III. The Accused Instrumentality

Product Identification

  • "Sun Generic XR Tablets," which are identified as generic copies of Xeljanz XR® (tofacitinib citrate extended release tablets, 11 mg) (Compl. ¶2, ¶24).

Functionality and Market Context

  • The accused product is an 11 mg extended-release tablet containing tofacitinib citrate as its active ingredient (Compl. ¶24, ¶26). As a generic version of Pfizer's Xeljanz XR, it is intended for once-daily administration for the treatment of conditions such as rheumatoid arthritis (Compl. ¶17-18). The infringement alleged is a statutory act based on the filing of ANDA No. 209790, which seeks FDA approval to market the product prior to the expiration of the ’181 patent (Compl. ¶2). No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

The complaint does not provide a detailed, element-by-element infringement analysis or an appended claim chart. The infringement theory is based on the statutory act of filing an ANDA for a product that is a generic copy of Pfizer's own Xeljanz XR® 11 mg product (Compl. ¶2, ¶24). The core allegation is that because Sun's proposed product is an 11 mg tofacitinib extended-release tablet seeking approval for the same use, its commercial manufacture and sale would infringe at least claim 2 of the '181 patent (Compl. ¶34, ¶36). The complaint notes that Sun's Paragraph IV notice did not include a noninfringement argument, instead alleging that all claims of the patent are invalid (Compl. ¶29-30).

  • Identified Points of Contention:
    • Validity vs. Infringement: The primary point of contention, as identified in the complaint, appears to be the validity of the ’181 patent, which Defendants challenge in their Paragraph IV certification (Compl. ¶30). The case will likely focus heavily on whether the asserted claims are valid over the prior art.
    • Technical Questions: Should a dispute over infringement arise, it may focus on whether Sun's formulation meets the functional limitations of the claims. This raises several questions:
      • Does the specific formulation detailed in Sun's ANDA deliver the drug "primarily by osmotic pressure," as required by claim 2, or by a different mechanism such as simple matrix erosion?
      • Do the bioequivalence studies in Sun's ANDA demonstrate that its product achieves the specific pharmacokinetic parameters recited in claim 2, such as the AUC range and the Cmax to Cmin ratio?

V. Key Claim Terms for Construction

While the complaint does not identify specific claim term disputes, the technology and claim language suggest the following terms may be critical.

  • The Term: "primarily by osmotic pressure"

  • Context and Importance: This term defines the core mechanism of drug release. Infringement of claim 2 hinges on whether the accused product operates via this mechanism. Practitioners may focus on this term because alternative sustained-release mechanisms exist (e.g., diffusion, erosion), and the evidence in the ANDA regarding the accused product's mechanism will be determinative.

  • Intrinsic Evidence for Interpretation:

    • Evidence for a Broader Interpretation: The patent describes several types of osmotic systems, including extrudable core systems and bilayer osmotic systems, suggesting the term is not limited to a single structure ('181 Patent, col. 20:27-46, col. 31:50-57). Parties may argue "primarily" implies that osmosis is the dominant, but not exclusive, release mechanism.
    • Evidence for a Narrower Interpretation: Parties may point to the detailed description of the extrudable core system in Example 1 as the key embodiment, arguing that "primarily by osmotic pressure" requires the specific structural and functional features of that example, such as a drilled delivery port ('181 Patent, col. 45:43-col. 48:35).

  • The Term: "osmagen"

  • Context and Importance: This is a required component of the tablet core. The scope of this term will determine which excipients in the accused product satisfy this limitation.

  • Intrinsic Evidence for Interpretation:

    • Evidence for a Broader Interpretation: The specification provides a broad definition, stating that "Typical classes of suitable osmagents are water-soluble salts, sugars, organic acids, and other low-molecule-weight organic compounds" ('181 Patent, col. 22:19-24). This language supports an interpretation that includes a wide variety of substances.
    • Evidence for a Narrower Interpretation: The examples consistently use sorbitol as the osmagen ('181 Patent, Table 1, Table 2). A party could argue that the term should be construed in light of these consistent examples to cover only similar types of sugar-based osmotic agents.

VI. Other Allegations

  • Indirect Infringement: The complaint alleges inducement of infringement against Sun Pharmaceutical Industries, Inc. (the U.S. subsidiary), asserting that it actively and knowingly participated in, contributed to, and directed the submission of the ANDA filed by Sun Pharmaceutical Industries Limited (the foreign parent) (Compl. ¶40-41).
  • Willful Infringement: The complaint does not contain a formal count for willful infringement. However, it alleges that Defendants had knowledge of the '181 patent at the time of their ANDA submission and requests a finding that the case is "exceptional" under 35 U.S.C. § 285, which would entitle Plaintiff to an award of attorneys' fees (Compl. ¶35; Prayer for Relief ¶E).

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

The resolution of this case will likely depend on the answers to two central questions for the court:

  • A primary question of patent validity: As Defendants' Paragraph IV certification focuses on invalidity, a core issue will be whether the asserted claims of the ’181 patent, which cover a specific pharmacokinetic profile for a sustained-release formulation, are valid in light of the prior art available at the time of the invention.
  • A key evidentiary question of infringement: Assuming the patent is held valid, does the evidence contained within Defendants' confidential ANDA submission demonstrate that their proposed generic product meets all limitations of the asserted claims, particularly the functional requirements related to the drug delivery mechanism ("primarily by osmotic pressure") and the specific pharmacokinetic outcomes (AUC and Cmax/Cmin ratio)?