In an effort to combat pharmaceutical patent holders, several companies are now filing petitions for post-grant review on the theory that the claims are unpatentable for lacking sufficient written description and enablement. Although the number of post-grant review proceedings remains fairly small in comparison to inter-partes review proceedings, the recent increase in filings by generic drug and biosimilar manufacturers suggests a new trend for challenging pharmaceutical and biological patents.

For example, in Grünenthal GmbH v. Antecip Bioventures II LLC, No. PGR2017-00008, Paper No. 7 (P.T.A.B. July 7, 2017), the PTAB instituted post-grant review of claims 1-17 of U.S. Patent No. 9,283,239 for lack of written description under 35 U.S.C. § 112(a). Specifically, the PTAB concluded that Grünenthal established the reasonable likelihood that the claims are unpatentable because of the lack of sufficient written description of the dosing regimen limitation in claim 1. The PTAB declined to institute review on the grounds of enablement, anticipation, and obviousness.

The ʼ239 patent recites oral dosage forms of bisphosphonate compounds, including zoledronic acid, for use in treating pain or other similar conditions, such as Complex Regional Pain Syndrome. Independent claim 1 recites “a method of treating complex regional pain syndrome comprising orally administering zoledronic acid to a human being in need hereof, wherein the human being receives about 80 to about 500 mg of zoledronic acid within a period of six months.” Id. at 4. The ʼ239 patent issued on March 15, 2016, and claims priority to three AIA non-provisional applications, as well as 11 provisional applications (10 pre-AIA).

Initially in its decision, the PTAB addressed whether the ʼ239 patent was eligible for post-grant review. To be eligible, the challenged patent must have an effective filing date of on or after March 16, 2013. Grünenthal argued that the challenged patent was eligible for review because it was not entitled to the filing date of the earlier pre-AIA provisional applications. For a patent to be entitled to the benefit of an earlier filing date, the claimed invention must be disclosed in the earlier application in compliance with § 112(a) requirements.

Grünenthal argued that certain claim limitations were not disclosed in the pre-AIA provisional applications. The PTAB agreed that the pre-AIA provisional applications failed to disclose the dosing limitation of claim 1 and the percentage limitation of claim 17 in a manner provided by 112(a). With respect to claim 1, the PTAB concluded that the provisional applications failed to describe the particular dosing range claimed. The PTAB noted that some applications only disclosed ranges of “about 0.005mg to about 20 mg” while others disclosed broader ranges of “about 10 mg to 500 mg,” but that none disclosed the claimed range.  Id. at 10-11.

With respect to claim 17, the PTAB similarly concluded the provisional applications failed to disclose the limitation of a “dosage form containing at least 10% zoledronic acid.” Id. at 13. The PTAB rejected Antecip’s argument that the limitation should be inferred from the disclosure of an oral dose of about 100mg, 200mg, or 300 mg of zoledronic acid, noting that “a description of an oral dose of zoledronic acid is neither a description of an oral dosage for nor a description of a concentration of zoledronic acid in an oral dosage form.” Id. at 13.  Ultimately, the PTAB concluded that the ‘239 patent was eligible for post-grant review.

Among its grounds for unpatentability, Grünenthal asserted that the ʼ239 patent claims were unpatentable under § 112(a) for insufficient written description of the dosing limitation, “about 80 to about 500 mg of zoledronic acid within a period of six months.” The dosing limitation was not present in the original application but instead was only first added by amendment during prosecution. The limitation was again later amended by Examiner’s Amendment to avoid prior art.

In reaching its decision, the PTAB followed the same line of reasoning as it did for determining post-grant review eligibility and rejected a number of arguments asserted by Antecip. Antecip argued that although the specification does not explicitly state the claimed dosing regimen as an independent range, § 112(a) does not require explicit disclosure. In support of its argument, Antecip relied on the specification’s general description of several oral dosage ranges for zoledronic acid such as “0.005mg to about 20mg” and “about 100mg to about 2000mg” to provide sufficient written description. Antecip further argued that the upper limit of 500mg of the claimed range was disclosed several times within the specification and that there was overlap with the recited range in independent claim 1.

However, the PTAB was unpersuaded by Antecip’s assertions, noting that the specification contained no mention of the 80 mg lower limit of the claimed range. The PTAB also pointed out that the specification failed to demonstrate any criticality behind the particular range chosen for claim 1. Quoting Purdue Pharma L.P. v. Faulding Inc., 230 F.3d 1320, 1326 (Fed. Cir. 2000), the PTAB stated “neither the text accompanying the examples, nor the data, nor anything else in the specification in any way emphasizes the [recited limitation].” The PTAB concluded that the specification contained no description suggesting the dosing regimen limitation was significant and as such, a person of ordinary skill in the art upon reading the specification would not have been directed to create a dosing range of “about 80mg to about 500 mg.” Therefore, the PTAB agreed with Grünenthal and instituted review of claims 1-17 for lack of written description.

Although the PTAB’s decision appears to be straightforward, this decision demonstrates the importance behind careful construction of a specification. Patent owners need to be sure to draft specifications to disclose a variety of both broad and narrow ranges so as to ensure there is adequate support if amendments are made during prosecution. Additionally, patent owners should take note of the criticality of a recited range, as it will further support the importance of particular claim limitations.

This decision is also the first of several post-grant review decisions the PTAB will issue this year on patents directed towards pharmaceuticals and biologics. We will continue to keep you informed of the PGR proceedings involving pharmaceutical patents as these cases continue to develop.