Patenting Polymorphs: Opportunities and Challenges

The development of pharmaceutical products for FDA approval in the U.S. is often expensive and unpredictable. Compositions and formulations may evolve and, as developed over time, may be separately patentable over earlier U.S. patent filings and might offer many years of additional patent exclusivity. Crystal forms are generally complicated and unpredictable, which can be determinative when considering obviousness and inherent anticipation. However, such arguments might negatively affect written description support of certain claims.

Different crystal forms may have different physicochemical properties that can be claimed. These elements can impact patentability/validity arguments as well as infringement arguments. For example, characterizing information such as IR, Raman, NMR, X-ray, DSC, density, cell parameters, melting point, color, and intensity in a claim may be considered elements of the claim that will need to be proven to show infringement.

The panel will use three recent cases to discuss the opportunities and challenges presented by claiming polymorphs: Gilead Sciences Inc. v. Apotex Inc., (D. Del. 2021); Amgen Inc. v. Sandoz Inc., (D. N.J.), Judge Shipp of the District Court of New Jersey; and BMS v. Sigmapharm Labs. L.L.C., (Fed. Cir. 2021). They will also reference two crystal patents relating to the Allegra product having claims of particular interest. These decisions and the exemplary Allegra patents are excellent examples of the detail-oriented nature of polymorph U.S. patent applications, their prosecution, and litigation, particularly in the ANDA context.

Crystal forms may require considerations involving balancing the ability to prove validity/patentability against proving infringement in litigation. Think through the pros and cons of the following types of claims, for example:

• Claim(s) that simply refer to the unique crystal form(s)
• Claim(s) having some characterization data that uniquely identifies the crystal form(s)
• Claims drawn to process(es) of making the unique crystal form(s)

Consideration of Section 112(f) means-plus-function claims might also be useful. By using a linking table to a specific active ingredient crystal, the claim could, in the language of 112(f), be construed to cover the corresponding structure, material, or acts described in the specification (i.e., the specific crystal disclosed) and equivalents thereof. 112(f) equivalents would be literal equivalents, not equivalents under the doctrine of equivalents.

Listen as our authoritative panel of patent attorneys examines patenting drug formulations from drafting through patent prosecution and enforcement. The panel will further explore lessons learned from the case law and offer strategies to overcome the potential challenges.