PTAB

IPR2016-01316

Mylan Pharmaceuticals Inc v. AstraZeneca Ab

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Petition
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1. Case Identification

2. Patent Overview

  • Title: Method of Treating Breast Cancer with a Fulvestrant Formulation
  • Brief Description: The ’122 patent relates to methods for treating hormone-dependent diseases, particularly breast cancer, by administering an intramuscular injection of a specific long-acting pharmaceutical formulation of fulvestrant in a castor oil vehicle.

3. Grounds for Unpatentability

Ground 1: Claims 1-9 are obvious over McLeskey.

  • Prior Art Relied Upon: McLeskey (a 1998 research paper titled “Tamoxifen-resistant fibroblast growth factor-transfected MCF-7 cells are cross-resistant in vivo to the antiestrogen ICI 182,780 and two aromatase inhibitors”).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that McLeskey rendered all challenged claims obvious by disclosing the exact pharmaceutical formulation recited in the claims. McLeskey described using a “50 mg/mL preformulated drug [fulvestrant] in a vehicle of 10% ethanol, 15% benzyl benzoate, 10% benzyl alcohol, brought to volume with castor oil.” This formulation, provided to the researchers by the Patent Owner’s predecessor, matches every claimed excipient and concentration. Petitioner asserted that the other claim elements—treating breast cancer with fulvestrant and administering it via intramuscular injection for long-acting effects—were widely known in the prior art. The plasma concentration recited in claim 1 was argued to be a non-limiting statement of intended use, but even if given patentable weight, it represented an expected and predictable outcome of administering such a known depot formulation.
    • Key Aspects: Petitioner contended the patent was allowed during prosecution based on an argument of “unexpectedly improved solubility.” However, the Patent Owner failed to disclose McLeskey to the Examiner. Petitioner argued that McLeskey’s public disclosure of this exact, successful formulation years prior to the patent’s priority date entirely negated any argument of unexpectedness or nonobviousness.

Ground 2: Claims 1-9 are obvious over Howell 1996 in view of McLeskey.

  • Prior Art Relied Upon: Howell 1996 (a clinical study titled “Pharmacokinetics, pharmacological and anti-tumour effects of the specific anti-oestrogen ICI 182780 in women with advanced breast cancer”) and McLeskey.
  • Core Argument for this Ground:
    • Prior Art Mapping: Howell 1996 taught a method of treating women with advanced breast cancer using a long-acting, castor oil-based fulvestrant formulation administered via a 5 mL monthly intramuscular injection. It demonstrated that this method was tolerable, efficacious, and could maintain therapeutic blood plasma concentrations for at least one month. Specifically, Howell 1996 reported achieving mean end-of-month concentrations of 3.1 ng/mL, satisfying the limitation of claim 1. While Howell 1996 described the depot vehicle and administration method, it did not specify the exact excipients.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSA), seeking to practice the established breast cancer treatment method taught by Howell 1996, would combine its teachings with a specific, proven formulation for a long-acting fulvestrant depot. McLeskey provided the explicit recipe for such a formulation, which was known to be effective in breast cancer models and was even supplied by the same entity that supplied the formulation for the Howell 1996 study.
    • Expectation of Success: A POSA would have a high expectation of success in using the specific formulation from McLeskey to carry out the clinical method taught in Howell 1996. The components were identical in purpose (long-acting fulvestrant depot for breast cancer), and combining them would yield only predictable results.

4. Key Claim Construction Positions

  • "whereby a therapeutically significant blood plasma fulvestrant concentration of at least 2.5 ngml⁻¹ is attained for at least 2 weeks after injection": Petitioner argued this concluding clause in claim 1, and similar clauses in dependent claims, are non-limiting statements of intended result. The argument was that the clause merely states the expected outcome of performing the preceding, structurally complete method steps. Petitioner asserted that because the clause adds no new steps or limitations to the method itself, it should be afforded no patentable weight in the obviousness analysis.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-9 of Patent 6,774,122 as unpatentable under 35 U.S.C. §103.