Polymorphs are patentable subject matter in Canada and the
U.S. Our prior article discussed some best practices to
differentiate a new polymorph from the prior art and establish its
inventiveness. Recent court decisions from Europe and Japan
may be helpful for determining the best way to file not just
internationally, but also in North America.
Applicants looking to patent internationally need to be familiar
with the types of issues that courts have considered in key
regions, like Japan and Europe. This provides insight on local
patentability standards, and further highlights best practices for
properly drafting a patent application that will be filed
A thorough disclosure that supports the invention, establishes
inventiveness, and fully discloses how to obtain the claimed
polymorph will offer the highest likelihood of successfully
obtaining a patent for a crystalline version of a known compound. A
recent decision of the Japanese IP High Court (IPHC) in late 2012
dealt with the patentability of a crystalline form of the drug
Lipitor®.1 The IPHC stated that
Japanese Patent No. 3296564 did not adequately enable a person
skilled in the art to make the polymorph: the patent did not
specify factors such as a pH value, slurry concentration,
temperature, and other additives, all of which strongly affect
crystallization. The IPHC also stated that because crystalline
versions of compounds generally have superior effects for
pharmaceutical compounds with respect to stability, purity, and
ease of handling, it would be obvious to a person skilled in the
art to try to crystallize the non-crystalline compound. The method
chosen for forming the crystal was also one that one skilled in the
art using common general knowledge would think to apply when
attempting to form the crystal.
Europe also allows the patenting of crystal forms of known
compounds. The application must disclose the invention
sufficiently to be carried out by a person skilled in the
art.2 In an appeal case, the European Patent Office
found that a patent application lacked sufficient disclosure as its
claims specified that the claimed crystal was to be made by "a
seed being added".3 However, the "seed"
was composed of the product that was sought to be
synthesized. Therefore, the invention could not be practiced
without already having made the claimed product.
In Europe, the claimed product must also be defined by its
physical parameters (a common claim strategy in other jurisdictions
too). For a claimed polymorph, this could include XRPD,
single crystal X-ray diffraction, solid-state 13C NMR
spectroscopy, and/or infrared (IR) or Raman spectroscopy. A
difficulty arises as the burden of proof is on the applicant to
show that their product is novel over the prior art, even where the
prior art does not list these physical parameters. The
Applicant may benefit from running experiments on the products made
using the prior art to show that the claimed polymorph is novel,
and including these experiments in the patent application. Finally,
the crystal synthesized must exhibit unexpected
characteristics—merely picking one polymorph that offers no
benefit over the other possible polymorphs does not satisfy the
requirement of inventiveness, nor does a crystal showing the
benefits expected for the amorphous form (e.g. improvements in
stability, filtration, and drying).4
Patenting polymorphs internationally requires careful attention
to providing enough detail in the application to fully disclose and
support the invention, as well as establishing its inventiveness
compared to prior art. Reviewing cases where patents were
challenged in Europe and Japan shows the need to fully disclose the
conditions used to synthesize the crystal (solvents, temperatures,
times, pH values, etc.). Do not hold back on detail that may
help physically differentiate the polymorph from prior art, or that
could establish inventive functional benefits.
1 Sandoz K.K. v Werner-Lambert Company LLC, Case
No. 2011 (Gyo-Ke) 10445 (IPHC 2012).
2 Convention on the Grant of European Patents,
European Patent Convention, art 83.
3 Re Savior Lifetec Corporation, T 0097/11 –
4 Warner-Lambert Company LLC v Teva Pharmaceutical
Industries Ltd, T 0777/08 – 3.3.01.
The content of this article is intended to provide a general
guide to the subject matter. Specialist advice should be sought
about your specific circumstances.
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