Stephen G. Adrian | July 7, 2017

Storer v. Clark

June 21, 2017

Before Prost, Newman and Dyk.  Opinion by Newman.


Although the first-to-file provisions of the Leahy-Smith America Invents Act (AIA) went into effect March 16, 2013, interference proceedings are still with us, as highlighted by this decision from the Court of Appeals for the Federal Circuit (CAFC). An interference proceeding was declared December 3, 2013[1], between Storer’s U.S. Patent No. 7,608,600 (application filed June 27, 2003) and Clark’s pending application No. 11/854,218. The interfering claims are directed to treatment of hepatitis C using modified nucleoside compounds. Storer was initially designated senior party based upon its earlier provisional application No. 60/392,350, filed June 28, 2002. Clark claimed priority based on a provisional application filed May 30, 2003. Clark moved to deny Storer the priority date of the provisional application arguing that the provisional application did not enable a five-membered ring having a fluorine substituent in the 2’ (down) position:








The Patent Trial and Appeal Board (PTAB) held that Storer’s provisional application was not enabling for the count in the interference, and entered judgment granting priority to Clark.

The parties agreed that the only question at issue is whether Storer’s provisional application enables compounds having F in the 2’ (down) position (35 U.S.C. §112, first paragraph). The Board held that the provisional application, taken together with the prior art, did not enable the specific compounds having the identified structure.

“The enablement requirement is met where one skilled in the art, having read the specification, could practice the invention without ‘undue experimentation.’” Streck, Inc. v. Research & Diagnostic Sys., Inc., 665 F.3d 1269, 1288 (Fed. Cir. 2012) (quoting ALZA Corp. v. Andrx Pharm., LLC, 603 F.3d 935, 940 (Fed. Cir. 2010)). Thus, an analysis was made as to whether undue experimentation was required. As summarized in In re Wands, 858 F.2d 731, 737 (Fed. Cir. 1988), relevant factors to consider with respect to undue experimentation may “include (1) the quantity of experimentation necessary, (2) the amount of direction or guidance presented, (3) the presence or absence of working examples, (4) the nature of the invention, (5) the state of the prior art, (6) the relative skill of those in the art, (7) the predictability or unpredictability of the art, and (8) the breadth of the claims.”

Storer did not dispute the Board’s conclusions of the Wands’ factors 3, 4, 5, 6 and 8, but argued that these factors are not dispositive of enablement. The Board found with respect to 3-6 and 8:

(3) The provisional application contains no specific examples of synthesis of compounds having the fluoro substituent in the 2’ (down) position.

(4) At the time of the provisional application, although organic fluoridation mechanisms were generally known, a 2’-fluoro-2’-methyl nucleoside with the fluoro substituent in the down position had not yet been synthesized.

(5) although organic fluoridation techniques were well-known in the art at the time the S1 application (Storer’s provisional application) was filed, fluoridation of tertiary alcohols to produce a 2ˊ “down” tertiary fluorine was not taught or suggested by the prior art.

(6) The level of skill in the art was highly sophisticated: a person possessing the ordinary level of skill in this art, as of the time of invention, would hold a doctoral degree in the field of organic, synthetic, or medicinal chemistry with at least a year’s experience in the field of nucleoside synthesis or relevant drug discovery.

(8) Neither party argued the breadth of the claims.

Thus, a closer examination of the Wands’ factors 1, 2 and 7 is made ((1) the quantity of experimentation necessary; (2) the amount of direction or guidance presented; and (7) the predictability or unpredictability of the art).

Although not stated in the decision, the provisional application was over 5000 pages, listing many specific compounds. Storer argued that the provisional application “performed the substantial step of disclosing the precise chemical structure of the target compound.” However, the pages of the specification highlighted by Storer only provide generic formulas which encompass the “target compounds”. Storer further argued that the prior art (Matsuda Compound 17) is a “precursor compound that is only one step away from the target compound.”










This compound contains a methyl group instead of fluoro, which Storer agued would be readily convertible into the target compound by known methods to produce the desired stereochemistry. The Matsuda Compound 17, however, is not disclosed in the provisional application.

Storer attempted to rely upon three reaction schemes disclosed in the provisional application as a path that would lead to the claimed compounds. These reaction schemes, however, showed products with opposite stereochemistry. In addition, it was found that the art was highly unpredictable, which seemed to weigh heavily against Storer’s argument. Evidence had been presented supporting the unpredictability of synthesizing the target compound. Although it was recognized that undue experimentation depends on the subject matter and the skill in the art, it was found that a high amount of experimentation and skill was required.

On review, the CAFC concludes “that substantial evidence supports the Board’s findings that the synthetic schemes in Storer’s provisional application do not teach or suggest conversion of any precursor into the 2´F (down) structure, and that the Matsuda synthesis of a corresponding 2´- methyl (down), 2´-hydroxyl (up) structure does not enable a person of ordinary skill to produce the target compounds without undue experimentation.”

As concluded by the CAFC:

We conclude that substantial evidence supports the Board’s finding that “a high amount of experimentation is necessary to synthesize” the target compound. The record before the Board showed sufficient variability and unpredictability to support the Board’s conclusion that Storer’s provisional application did not enable the interference subject matter. The Board’s decision is affirmed.


Although an extensive disclosure in a provisional application may be sufficient to support a relatively broad claim scope, such disclosure may not be considered enabling for specific compounds (species) within the broad claim scope, particularly in an unpredictable art. As stated by Board, for new chemical compounds the specification must provide sufficient guidance that undue experimentation is not required to obtain the new compounds.

[1]Storer initially filed in the District of Delaware seeking review under 35 U.S.C. §146 (Idenix Pharmaceuticals, LLC v. Gilead Pharmasset LLC. This case was dismissed based on Biogen MA, Inc. v. Japanese Foundation for Cancer Research, 785 F.3d 648 (Fed. Cir. 2016), ruling that the AIA eliminated the option of district court review under §146 for interferences declared after September 15, 2012.


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