DCT

3:18-cv-06112

Mitsubishi Tanabe Pharma Corp v. Prinston Pharmaceutical Inc

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 3:18-cv-06112, D.N.J., 04/11/2018
  • Venue Allegations: Venue is alleged to be proper based on Defendant having a regular and established place of business in New Jersey and having committed acts of infringement within the district.
  • Core Dispute: Plaintiffs allege that Defendant’s filing of an Abbreviated New Drug Application (ANDA) to market a generic version of the diabetes drug Invokana® (canagliflozin) constitutes an act of infringement of a patent covering the drug's active chemical compound.
  • Technical Context: The technology concerns a specific glucopyranoside compound that functions as a sodium-dependent glucose transporter 2 (SGLT2) inhibitor, a major class of oral medications for the treatment of type 2 diabetes.
  • Key Procedural History: This action was initiated under the Hatch-Waxman Act following Defendant’s submission of ANDA No. 210514 with a Paragraph IV certification, asserting that the patent-in-suit is invalid. The patent-in-suit is listed in the FDA’s “Orange Book” as covering the brand-name drug Invokana®. The complaint notes related litigation against other generic manufacturers concerning the same patent family.

Case Timeline

Date Event
2003-08-01 ’788 Patent Priority Date
2011-05-17 ’788 Patent Issue Date
2018-03-27 Date of Prinston’s Paragraph IV Certification Notice Letter
2018-04-11 Complaint Filing Date

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

  • Patent Identification: U.S. Patent No. 7,943,788, titled “Glucopyranoside Compound,” issued May 17, 2011 (’788 Patent).

The Invention Explained

  • Problem Addressed: The patent describes a need for new therapeutic options for diabetes mellitus, noting that existing oral antidiabetic agents can have significant side effects, such as hypoglycemia or gastrointestinal issues, and are not always sufficient to control the disease ('788 Patent, col. 1:20-33). The central problem is managing hyperglycemia (abnormally high blood glucose), a hallmark of diabetes ('788 Patent, col. 1:33-42).
  • The Patented Solution: The invention provides a novel class of glucopyranoside compounds that function as inhibitors of the sodium-dependent glucose transporter (SGLT), which is responsible for the re-absorption of glucose in the kidneys and intestines ('788 Patent, col. 1:13-16). By inhibiting SGLT, the patented compounds cause excess glucose to be excreted from the body, thereby lowering blood glucose levels through an insulin-independent mechanism ('788 Patent, col. 1:43-52; col. 27:28-32). The core chemical scaffold is depicted as Formula (I) in the patent's abstract and detailed description ('788 Patent, Abstract).
  • Technical Importance: The development of SGLT inhibitors provided a new mechanistic class of oral antidiabetic drugs, offering an alternative or complementary treatment to existing therapies that modulate insulin secretion or sensitivity ('788 Patent, col. 27:28-48).

Key Claims at a Glance

  • The complaint asserts infringement of at least claims 12 and 20 (Compl. ¶28).
  • Independent Claim 20: This claim is directed to a single chemical compound, 1-(β-D-glucopyranosyl)-4-methyl-3-[5-(4-fluoro-phenyl)-2-thienylmethyl]benzene, presented via its specific chemical structure, or a pharmaceutically acceptable salt thereof.
  • Dependent Claim 12: This claim recites the same compound as claim 20 by its chemical name: "1-(β-D-glucopyranosyl)-4-methyl-3-[5-(4-fluoro-phenyl)-2-thienylmethyl]benzene, or a pharmaceutically acceptable salt thereof." This claim depends from a chain tracing back to the genus claim, Claim 1.
  • The complaint's phrasing "at least claims 12 and 20" suggests Plaintiffs reserve the right to assert additional claims from the ’788 patent (Compl. ¶28).

III. The Accused Instrumentality

  • Product Identification: The accused instrumentality is Defendant Prinston’s proposed generic canagliflozin tablets in 100 mg and 300 mg dosages, for which it seeks FDA approval via ANDA No. 210514 (Compl. ¶24).
  • Functionality and Market Context:
    • The act of infringement alleged is the submission of the ANDA itself, which seeks approval to market a generic drug for a use claimed in a patent, an act defined as infringement under 35 U.S.C. § 271(e)(2) (Compl. ¶27).
    • The active pharmaceutical ingredient (API) of the accused product is canagliflozin, which is the same API in Plaintiffs’ brand-name drug, Invokana® (Compl. ¶¶21, 24).
    • The complaint alleges that if Prinston’s ANDA is approved, it will manufacture and sell its generic product in the United States, directly competing with Invokana® prior to the expiration of the ’788 Patent (Compl. ¶¶10, 28).

IV. Analysis of Infringement Allegations

The complaint does not provide an element-by-element claim chart. The infringement theory is based on the legal framework of the Hatch-Waxman Act, where the submission of an ANDA for a generic version of a branded drug is a technical act of infringement. The core allegation is that the API in Prinston’s proposed product, canagliflozin, is the same chemical compound protected by the asserted claims.

No probative visual evidence provided in complaint.

  • Identified Points of Contention:
    • Structural Identity: The central infringement question is whether the API in Prinston's ANDA product, canagliflozin, is the specific chemical compound recited by name in claim 12 and by structure in claim 20. As an ANDA filer seeking to market a bioequivalent generic, Prinston’s product is expected to contain the same API as the reference listed drug, Invokana®. Publicly available information identifies the structure of canagliflozin as being identical to that claimed in claims 12 and 20.
    • Validity, Not Infringement: The primary dispute in this ANDA litigation will likely not be over infringement but over the validity of the ’788 patent. Prinston has made a Paragraph IV certification that the claims of the ’788 patent are invalid (Compl. ¶25), placing the burden on Prinston to prove invalidity by clear and convincing evidence at trial.

V. Key Claim Terms for Construction

In litigation over specific chemical compound claims, claim construction disputes are less common than in other technical fields. However, the scope of certain terms can still be at issue.

  • The Term: "pharmaceutically acceptable salt thereof"
  • Context and Importance: This term appears in both asserted claims 12 and 20. Its construction is important because it defines the scope of protection beyond the base compound itself. A defendant could potentially design a product using a novel salt form and argue that it falls outside the definition of a "pharmaceutically acceptable salt" as understood and enabled by the patent. Practitioners may focus on this term to determine if the specific salt form in the accused generic product is covered by the claims.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification provides a broad, exemplary list of potential salts, including those formed with inorganic acids, organic acids, and metals. The use of the phrase "for example" suggests this list is not exhaustive, supporting an interpretation that covers any salt suitable for pharmaceutical use ('788 Patent, col. 7:36-50).
    • Evidence for a Narrower Interpretation: A party seeking a narrower scope might argue that the term is limited to the types of salts explicitly disclosed or those that can be formed using the "conventional method" mentioned in the specification ('788 Patent, col. 7:38-39). This argument may be raised if the accused product uses a highly unconventional salt form not contemplated by the patent's disclosure.

VI. Other Allegations

  • Indirect Infringement: The complaint alleges that Prinston will induce infringement by patients and physicians and contribute to infringement by third parties if its ANDA is approved (Compl. ¶28). The basis for this allegation is Prinston’s intent to market the generic drug with a label instructing its use for the patented therapeutic purpose, thereby encouraging direct infringement by end-users (inducement) and supplying a material component for that infringement (contribution).
  • Willful Infringement: The complaint does not explicitly allege "willful infringement" but does assert that this is an "exceptional one" and seeks an award of attorneys' fees pursuant to 35 U.S.C. § 285 (Compl. ¶30; Prayer for Relief ¶E). The basis for this claim is not detailed but is a standard inclusion in ANDA complaints.

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

The resolution of this case will likely depend on the court's determination of the following central questions:

  1. Patent Validity: The core issue, prompted by Defendant’s Paragraph IV certification, will be one of validity: can Prinston prove by clear and convincing evidence that claims 12 and 20 of the ’788 patent are invalid, likely on grounds of obviousness in view of prior art compounds or for failure to meet the written description or enablement requirements of 35 U.S.C. § 112?
  2. Infringement Scope: While infringement appears straightforward, a secondary question concerns structural identity: is the active pharmaceutical ingredient in Prinston's ANDA—including its specific salt or crystalline form—a "compound" or "pharmaceutically acceptable salt thereof" as defined and covered by the asserted claims?
  3. Exceptional Case Status: A final question for the court will be whether Defendant's conduct before or during the litigation warrants a finding that the case is "exceptional" under 35 U.S.C. § 285, which would permit an award of attorneys' fees to the prevailing party.