PTAB

PGR2025-00036

Azurity Pharmaceuticals Inc v. Heron Therapeutics Inc

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Emulsion Formulations for Intravenous Administration
  • Brief Description: The ’255 patent relates to injectable oil-in-water emulsion formulations containing aprepitant, a drug used to prevent chemotherapy-induced nausea and vomiting. The claims recite specific weight percentage ranges for aprepitant (0.7-0.8 wt%) and a high concentration of an emulsifier (13-20 wt/wt%), along with other standard emulsion components.

3. Grounds for Unpatentability

Ground 1: Claims 1-30 are obvious over Zhou in view of Washington, Bagwe, Weng, and Wan.

  • Prior Art Relied Upon: Zhou (CN 102379845), Washington (a 1996 journal article), Bagwe (a 2001 journal article), Weng (a 2012 journal article), and Wan (Application # 2011/0038925).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Zhou, a Chinese patent application, is nearly anticipatory. It discloses an injectable aprepitant emulsion with ranges that encompass or are adjacent to nearly every claimed component: aprepitant (0.05-2%), oil (5-30%), co-emulsifier (1-10%), and tonicity agent (5-20%). The primary distinction is the emulsifier concentration, which Zhou discloses as 0.5-10 wt% while claim 1 of the ’255 patent requires 13-20 wt%. Dependent claims reciting specific components like soybean oil, ethanol, and sucrose are also taught as preferred embodiments in Zhou.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSA) would have been motivated to increase the emulsifier concentration in Zhou’s formulation to solve known stability and drug-loading problems associated with aprepitant. Washington taught that poorly soluble drugs like aprepitant must be loaded at the oil-water interface, requiring a large surface area. The art further taught that increasing emulsifier concentration reduces emulsion droplet size, thereby increasing the total interfacial surface area available for drug loading and improving overall stability. Bagwe explicitly disclosed that parenteral emulsions can contain 1-20% emulsifier, directly teaching the range now claimed in the ’255 patent. A POSA would thus combine Zhou's aprepitant formulation with the established principles in Washington and Bagwe to increase the emulsifier content into the claimed range.
    • Expectation of Success: A POSA would have had a reasonable expectation of success because increasing emulsifier concentration was a well-known, standard technique for optimizing emulsion stability. The process of adjusting a known formulation's excipient levels to find an optimal "window" of stability was a matter of routine experimentation, not invention. Given Bagwe's disclosure of up to 20% emulsifier in emulsions, a POSA would reasonably expect to successfully create a stable aprepitant formulation within this known range.

Ground 2: Claims 1-30 are unpatentable for lack of written description and/or enablement under 35 U.S.C. §112.

  • Core Argument for this Ground: Petitioner contended that the Patent Owner is estopped by its own prior arguments. In a previous district court litigation involving a related patent (claiming 14% emulsifier), the Patent Owner argued strenuously that the field of emulsion formulation was highly unpredictable. They asserted that increasing emulsifier concentration was counter-intuitive and expected to destabilize the emulsion, and that their 14% concentration was "critical," "unprecedented," and yielded "unexpected" results.
  • Petitioner argued that these admissions establish that a POSA would have been highly skeptical that emulsions with even higher emulsifier concentrations (up to 20%) could be successfully made. Given this proclaimed unpredictability, the ’255 patent specification, which lacks a single working example of an emulsion with more than 15% emulsifier or a ratio of emulsifier-to-aprepitant greater than 20:1, fails to provide adequate written description. It does not demonstrate to a skeptical POSA that the inventors were in possession of the full, broad scope of the claimed invention. For the same reasons, the specification fails to enable the full scope of the claims without undue experimentation.

4. Key Claim Construction Positions

  • "emulsion": Petitioner argued that the patent's express definition should control: "a colloidal dispersion of two immiscible liquids in the form of droplets, whose diameter, in general, is between 10 nanometers and 100 microns." This construction is critical because it is broad enough to encompass systems described in the art as "microemulsions" (such as Zhou) and "nanoemulsions." This preempts any argument that prior art disclosing microemulsions is not relevant to the claimed "emulsions."

5. Arguments Regarding Discretionary Denial

  • §314(a) (Fintiv): Petitioner stated it will file a Sotera stipulation upon institution, agreeing not to pursue in a parallel district court proceeding the same grounds raised in the petition or any grounds that reasonably could have been raised. This stipulation is intended to prevent a discretionary denial under the Fintiv factors.
  • §325(d) (Advanced Bionics): Petitioner argued against denial, asserting that the examiner made a material error. Although the Zhou reference was cited during prosecution, it was never used in an obviousness rejection. Crucially, the examiner did not have the benefit of the Patent Owner's admissions from prior litigation regarding the unpredictability of the art, which are central to both the motivation to combine and written description arguments. Furthermore, the written description and enablement grounds were never considered during prosecution.

6. Relief Requested

  • Petitioner requested the institution of a Post Grant Review and the cancellation of claims 1-30 of Patent 12,115,255 as unpatentable.