Patent Law

Sanofi prevails on PLAVIX at CAFC: enantiomer patentable over racemate

By Lawrence B. Ebert, Esq.

Claimed subject matter is ?anticipated? when it is not new; that is, when it was
previously known. Invalidation on this ground requires that every element and limitation of the claim was previously described in a single prior art reference, either expressly or inherently, so as to place a person of ordinary skill in possession of the invention. See Schering Corp. v. Geneva Pharms., Inc., 339 F.3d 1373, 1379 (Fed. Cir. 2003); Continental Can Co. USA v. Monsanto Co., 948 F.2d 1264, 1267-69 (Fed. Cir. 1991). An anticipating reference must be enabling; that is, the description must be such that a person of ordinary skill in the field of the invention can practice the subject matter based on the reference, without undue experimentation. See Amgen Inc. v. Hoechst Marion Roussel, Inc., 457 F.3d
1293, 1306-07 (Fed. Cir. 2006); Elan Pharms., Inc. v. Mayo Found. for Med. Educ. &
Research, 346 F.3d 1051, 1054 (Fed. Cir. 2003). Anticipation is a question of fact, and the district court?s finding of this issue is reviewed for clear error. See Merck & Co. v. Teva \Pharms. USA, Inc., 347 F.3d 1367, 1369 (Fed. Cir. 2003).

(...)

The district court found that although the racemate is in the prior art, the dextrorotatory enantiomer and salt in claim 3 of the ?265 patent are not described, either explicitly or inherently, in any reference.

(...)

Apotex states that the separation of enantiomers is routine, even if time-consuming or requiring some experimentation, and thus that that the separation need not have been performed or described in the reference. Apotex states that the properties of the enantiomers of PCR 4099 are inherently and necessarily present in its known racemate, such that when the enantiomers are separated the previously observed properties are ?immediately recognized? in one or the other enantiomer.

(...)

The district court analyzed the question as whether a generic disclosure necessarily
anticipates everything within the genus, and recognized that the answer depends on the
factual aspects of the specific disclosure and the particular products at issue. See, e.g., Atofina v. Great Lakes Chem. Corp., 441 F.3d 991, 999 (Fed. Cir. 2006) (?It is well established that the disclosure of a genus in the prior art is not necessarily a disclosure of every species that is a member of that genus.?).

[The CAFC concluded] The district court did not clearly err in finding that the statements in the ?596 patent and its Canadian counterpart that the products therein consist of enantiomers are not a description of the specific dextrorotatory enantiomer clopidogrel or a suggestion of its unusual stereospecific properties.

*** Of the issue of the racemate enabling the enantiomer: Apotex argues that it is entitled to a presumption of enablement because the asserted references are patents, which are presumed to be enabling because they are presumed valid, citing Amgen Inc. v. Hoechst Marion Roussel, Inc., 314 F.3d 1313, 1355 (Fed. Cir. 2003) (?We hold that an accused infringer should be similarly entitled to have the district court presume the enablement of unclaimed (and claimed) material in a prior art patent
defendant asserts against a plaintiff.?). Apotex argues that the presumption should be particularly strong here, because the prior art patents belong to Sanofi.

The CAFC noted: Any presumption of enablement of prior art does not exclude consideration of whether undue experimentation would be required to achieve enablement. See, e.g., Elan Pharms, 346 F.3d at 1054 (the reference must teach how to carry out the invention without undue experimentation). (...) In Forest
Laboratories, Inc. v. Ivax Pharmaceuticals, Inc., 501 F.3d 1263 (Fed. Cir. 2007), this court recognized the known difficulty of separating enantiomers and the unpredictability of their properties, and held that a reference that stated that a compound has enantiomers did not enable the separation of those enantiomers, where the reference did not teach how to obtain the enantiomer. Id. at 1268-69. We discern no clear error in the district court?s finding herein that the reference patents would not have enabled a person of ordinary skill to obtain clopidogrel substantially separated from the levorotatory enantiomer.

Of obviousness: The district court found that this separation was not a simple or routine procedure and that success in separation, as well as the allocation of properties, was unpredictable. (...) We discern no error in the district court?s findings that, on the state of the prior art, a person of ordinary skill would not have had the expectation that separating the enantiomers would be likely to produce an isomer having absolute stereoselectivity as to both the favorable antiplatelet activity and the unfavorable neurotoxicity.

***Cravath represented the prevailing party:

Evan R. Chesler, Cravath, Swaine & Moore LLP, of New York, New York, argued
for plaintiffs-appellees. With him on the brief were Richard J. Stark and David
Greenwald. Of counsel on the brief were Robert L. Baechtold, John D. Murnane, and
William E. Solander, Fitzpatrick, Cella, Harper & Scinto, of New York, New York.

Full post as published by IPBiz on December 12, 2008 (boomark / email).