Federal Circuit Scrutinizes Written Description In Provisional Application

23 April 2019 PharmaPatents Blog
Author(s): Courtenay C. Brinckerhoff

Provisional applications tempt stakeholders with the possibility of securing a filing date on an expedited basis and limited budget, but the value of that filing date will depend on its ability to serve as a valid priority date for the invention claimed in the non-provisional application. The non-precedential Federal Circuit decision in Purdue Pharma L.. v. Iancu shows that even a robust provisional application may not suffice if it does not include "blaze marks" that point out the claimed invention with "adequate specificity."

The Patent At Issue

The patent at issue was Purdue Pharma's U.S. Patent 9,034,376, directed to controlled release oral dosage forms of oxycodone.  The court considered claim 1:

1. A controlled release oral solid dosage form comprising: a controlled release matrix comprising a mixture of
(i) from 2.5 mg to 320 mg oxycodone or a pharmaceutically acceptable salt thereof; and
(ii) a gelling agent comprising polyethylene oxide and hydroxypropylmethylcellulose,
the gelling agent in an effective amount to impart a viscosity of at least 10 cP when the dosage form is subjected to tampering by dissolution in from 0.5 to 10 ml of an aqueous liquid;
the controlled release matrix providing a therapeutic effect for at least 12 hours when orally administered to a human patient.

The patent was challenged in Inter Partes Review (IPR) proceedings brought by Amneal Pharmaceuticals LLC, and also was the subject of parallel district court litigation. The USPTO Patent Trial and Appeal Board (PTAB) found the challenged claims invalid as obvious. Purdue appealed. Amneal did not participate in the appeal, but the USPTO intervened to defend the PTAB decision.

The Federal Circuit Decision

The Federal Circuit decision was authored by Judge Bryson and joined by Judges Dyk and Mayer. The court addressed several issues, but this article focuses on the priority claim.

The '376 patent stems from an application filed August 14, 2014, and claims priority to U.S. provisional application 60/310,534, filed August 6, 2001--thirteen years earlier. Citing its decisions in Dynamic Drinkware and New Railhead Manufacturing, the court considered whether the specification of the provisional application satisfied the written description and enablement requirements of 35 U.S.C. § 112 with regard to the subject matter claimed in the '376 patent, and in particular "a gelling agent comprising polyethylene oxide and hydroxypropylmethylcellulose."

The court considered the following paragraph from the provisional application:

In certain embodiments of the present invention wherein the dosage form includes an aversive agent comprising a gelling agent, various gelling agents can be employed including, for example and without limitation, sugars or sugar derived alcohols, such as mannitol, sorbitol, and the like, starch and starch derivatives, cellulose derivatives, such as microcrystalline cellulose, sodium carboxymethyl cellulose, methylcellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and hydroxypropyl methylcellulose, attapulgites, bentonites, dextrins, alginates, carrageenan, gum tragacanth, gum acacia, guar gum, xanthan gum, pectin, gelatin, kaolin, lecithin, magnesium aluminum silicate, the carbomers and carbopols, polyvinylpyrrolidone, polyethylene glycol, polyethylene oxide, polyvinyl alcohol, silicon dioxide, surfactants, mixed surfactant/wetting agent systems, emulsifiers, other polymeric materials, and mixtures thereof, etc. In certain preferred embodiments, the gelling agent is xanthan gum. In other preferred embodiments, the gelling agent of the present invention is pectin.

The court considered this paragraph as disclosing that "PEO and HPMC are merely two of many undifferentiated compounds that fall within the genus of gelling agents." The court acknowledged that the "mixtures thereof" language "suggests the possibility of combining two or more of the listed gelling agents," but still "fails to highlight any preference for how many and which gelling agents to combine." The court concluded:

Such “laundry list” disclosures do not provide adequate specificity to constitute written description support for Purdue’s claim of priority.

The court also cited In re Ruschig in support of its conclusion that the "additional references to PEO and HPMC throughout the provisional application" did not provide "blaze marks" that point to the claimed combination over "any of the many others which could also be made.”

Because "the claims of the ’376 patent do not have written description support in the ’534 provisional application," they were not entitled to its filing date, and so were subject to invalidation based on intervening prior art.

The Written Description Collateral Attack

The disclosure of the '376 patent does not appear to include more "blaze marks" highlighting "a gelling agent comprising polyethylene oxide and hydroxypropylmethylcellulose" than the provisional application did. Thus, the claims might have been vulnerable to a written description challenge. However, the IPR statute permits challenges "only on the basis of prior art consisting of patents or printed publications." This case illustrates how a collateral written description attack can be made in an IPR by asserting intervening prior art and forcing the patent holder to validate its priority claim.

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