DCT

1:17-cv-00315

ViiV Healthcare Co v. Lupin Ltd

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:17-cv-00315, D. Del., 03/23/2017
  • Venue Allegations: Venue is alleged to be proper in Delaware because Defendant Lupin Pharmaceuticals, Inc. is a Delaware corporation with a registered agent in the state, and both defendants are alleged to conduct substantial business in, place goods into the stream of commerce in, and have previously submitted to the jurisdiction of the court for other patent disputes.
  • Core Dispute: Plaintiffs allege that Defendants’ filing of an Abbreviated New Drug Application (ANDA) for a generic version of the HIV drug LEXIVA® (fosamprenavir calcium) constitutes an act of infringement of a patent directed to prodrugs of that active ingredient.
  • Technical Context: The technology relates to prodrugs of aspartyl protease inhibitors, a class of antiviral compounds critical for treating HIV, which were designed to improve solubility and oral bioavailability, thereby reducing the "pill burden" on patients.
  • Key Procedural History: This action was initiated under the Hatch-Waxman Act following a notice letter from Lupin regarding its ANDA filing. Subsequent to the complaint's filing, an Inter Partes Review (IPR) certificate for the patent-in-suit was issued. This certificate, reflecting the outcome of two IPR proceedings, indicates that the patent's independent Claim 1, along with claims 4-9, were cancelled. However, dependent composition claims 2-3 and dependent method claims 10-12—the very claims asserted in this litigation—were found patentable. This creates a significant legal question regarding the enforceability of dependent claims whose base claim has been cancelled.

Case Timeline

Date Event
1997-12-24 ’989 Patent Priority Date
2002-08-20 ’989 Patent Issue Date
2017-02-09 Lupin sends Notice Letter regarding ANDA filing
2017-03-23 Complaint Filing Date

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

U.S. Patent No. 6,436,989 - "Prodrugs of Aspartyl Protease Inhibitors," issued August 20, 2002

The Invention Explained

  • Problem Addressed: The patent describes a problem with prior HIV aspartyl protease inhibitors, such as VX-478. While effective, these compounds are highly hydrophobic, resulting in poor aqueous solubility and low oral bioavailability (U.S. Patent No. 6,436,989, col. 2:25-36). This necessitates large doses encapsulated in liquid, leading to a high "pill burden" for patients, which can decrease compliance and limit therapeutic benefit (U.S. Patent No. 6,436,989, col. 2:41-50).
  • The Patented Solution: The invention addresses this by creating prodrugs—chemically modified, inactive or less active precursors that are converted to the active drug in the body. The patent discloses modifying the parent inhibitor by adding specific chemical groups (such as a phosphate group) to create a new molecule with significantly improved aqueous solubility and bioavailability ('989 Patent, Abstract; col. 2:8-13). This allows for the creation of a solid dosage form (e.g., a tablet), reducing the number of pills a patient must take daily ('989 Patent, col. 2:60-65).
  • Technical Importance: The development of stable, soluble prodrugs enabled more patient-friendly and potentially more effective oral administration of a vital class of HIV treatments ('989 Patent, col. 1:13-16).

Key Claims at a Glance

  • The complaint asserts dependent composition claims 2 and 3, and dependent method of use claims 10, 11, and 12 (Compl. ¶25).
  • The asserted composition claims depend from Claim 1, which defines a genus of compounds with a specific chemical formula. Claim 3, incorporating the limitations of claims 1 and 2, is directed to a specific salt form of the compound:
    • A compound of the formula shown in Claim 1
    • Wherein the R7 group is a phosphate ester
    • Wherein the phosphate ester is a calcium salt (-PO3²⁻Ca²⁺)
  • The asserted method claims depend from Claim 10, which claims a method for treating HIV by administering a composition containing a compound of the invention.

III. The Accused Instrumentality

  • Product Identification: Defendants’ generic 700 mg fosamprenavir calcium tablets, for which approval is sought under ANDA No. 204130 (Compl. ¶1, ¶20).
  • Functionality and Market Context: The accused product is a generic version of Plaintiffs’ LEXIVA® drug (Compl. ¶1). By filing an ANDA, Defendants have represented to the FDA that their product contains the same active ingredient (fosamprenavir calcium), has the same dosage form and strength, and is bioequivalent to the branded drug (Compl. ¶21). The product is intended for the treatment of HIV infection (Compl. ¶22).

IV. Analysis of Infringement Allegations

No probative visual evidence provided in complaint.

  • '989 Patent Infringement Allegations
Claim Element (from Independent Claim 1, as incorporated into asserted Claim 3) Alleged Infringing Functionality Complaint Citation Patent Citation
A compound of the formula: [structure depicted] The complaint alleges that Defendants' product contains fosamprenavir calcium, which is the commercial embodiment of the claimed compound. By filing an ANDA, Defendants have represented that their product contains this active ingredient. ¶1, ¶19, ¶21 col. 74:29-49
wherein R⁷ is selected from ... -PO₃²⁻Ca²⁺ The accused product is explicitly identified as a "fosamprenavir calcium" tablet, which the complaint alleges falls within the scope of Claim 3. ¶1, ¶19 col. 74:51-53
  • Identified Points of Contention:
    • Legal Question (Enforceability): A central legal issue, arising from post-filing IPR proceedings, is the enforceability of the asserted dependent claims (2, 3, 10-12). Given that the independent claims upon which they rely (Claim 1 and Claim 4) were cancelled, the court will have to determine if the surviving dependent claims can be asserted directly or if a procedural step, such as a reissue, is required to render them enforceable.
    • Technical Question (Infringement): In ANDA litigation, the act of filing the application to market a generic equivalent is the act of infringement. Assuming the claims are enforceable, the primary technical question would be whether the compound in Defendants' ANDA is structurally identical to the one claimed, including its specific stereochemistry. This is often not heavily contested, with the dispute focusing instead on the patent's validity.

V. Key Claim Terms for Construction

  • The Term: "a compound of the formula"
  • Context and Importance: In a chemical compound patent, the structural formula itself defines the invention. The construction of this term is critical because infringement hinges on whether Defendants' fosamprenavir calcium is identical to the compound defined by the specific structure and stereochemistry depicted in the patent's claims. Practitioners may focus on this term to ensure an exact structural correspondence, as any deviation in the accused product, including in its stereoisomeric form, could support a non-infringement argument.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The patent’s detailed description discloses a broad genus of compounds under Formula I, which could suggest the inventors contemplated variations beyond the specific examples (U.S. Patent No. 6,436,989, col. 4:45-50).
    • Evidence for a Narrower Interpretation: The structure depicted in the issued claims at column 74 shows specific stereocenters (i.e., the relative 3D arrangement of atoms). Furthermore, the specification emphasizes a particular stereochemistry, referring to the "syn" configuration as preferred and depicting specific stereoisomers in synthetic examples (U.S. Patent No. 6,436,989, col. 6:5-8; col. 29-30). This evidence suggests the term should be narrowly construed to cover only the specific stereoisomer shown in the claim.

VI. Other Allegations

  • Indirect Infringement: The complaint alleges induced and contributory infringement of the method claims (10-12). Inducement is based on the allegation that Defendants' product label will instruct physicians and patients to administer the tablets for treating HIV infection (Compl. ¶30-31). Contributory infringement is based on the allegation that fosamprenavir calcium is a material part of the invention, is especially adapted for this infringing use, and has no substantial non-infringing uses (Compl. ¶32-34).
  • Willful Infringement: The complaint does not contain an explicit allegation of willful infringement. However, it does allege that Defendants had "actual and constructive knowledge" of the ’989 Patent prior to filing the ANDA, which is a required element for willfulness (Compl. ¶29, ¶38).

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

  • A core issue will be one of legal enforceability: can the asserted dependent claims, which survived IPR, be enforced in district court now that the independent claims from which they depend have been cancelled by the USPTO? The case’s progression hinges on the answer to this threshold legal question.
  • A second key question will relate to validity: assuming the claims are deemed enforceable, the focus will likely shift to whether the claims are valid. Defendants will likely challenge the patentability of the specific fosamprenavir calcium salt as obvious over the prior art, forcing the court to evaluate the non-obviousness of this specific prodrug formulation.