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Federal Circuit provides more post-KSR guidance for obviousness for chemical compounds

July 24, 2008
Post by Blog Staff

In a decision Monday, the Federal Circuit affirmed a district court's decision finding asserted claims of a patent valid and enforceable. Specifically, the court affirmed a finding that the asserted claims were nonobvious as a matter of law, and that the evidence did not support a finding of inequitable conduct. The Federal Circuit, applying KSR Int'l Co. v. Teleflex Inc. in the context of similarly-structured chemical compounds stated: "[P]ost-KSR, a prima facie case of obviousness for a chemical compound still, in general, begins with the reasoned identification of a lead compound." In this case, because there was no adequate explanation for why the defendant's asserted "lead compound" would actually be used by one of ordinary skill in the art, the patent was not shown to be obvious.The defendants also brought several accusations of inequitable conduct, the court found none of them to be persuasive. The court held that in order to have a finding of inequitable conduct there must be a clear intent to deceive the Examiner and this is a very high standard. In this case, some questionable conduct had occurred, but ultimately the court said it was clear that no intent to deceive had existed. Therefore, no inequitable conduct had occurred. More on Eisai Co. v. Dr. Reddy's Labs., Ltd. after the jump.Eisai owns a patent for the chemical compound rabeprazole and its salts, as well as methods of use. Rabeprazole is a proton pump inhibitor used treat ulcers, heartburn, and other similar gastrointestinal disorders. Eisai markets the drug under the name Aciphex. It has been very successful, generating over $1 billion yearly in worldwide sales. Due to this success, Dr. Reddy's and Teva Pharmaceuticals filed Abbreviated New Drug Applications seeking to produce a generic version of rabeprazole before the patent expired. In response, Eisai brought suit against both Dr. Reddy's and Teva for infringement. Before the district court, both Dr. Reddy's and Teva admitted infringement, but argued the patent was unenforceable due to inequitable conduct; Teva also argued the patent was invalid for obviousness. The district court held the patent was not invalid for obviousness and that no inequitable conduct had occurred during prosecution. Both defendants appealed.The Federal Circuit first addressed obviousness. The court first noted the analysis of the differences between the prior art and the claimed invention "often turns on the structural similarities and differences between the claimed compound and the prior art compounds." Obviousness can then be shown "by identification of some motivation that would have led one of ordinary skill in the art to select and then modify a known compound (i.e. a lead compound) in a particular way to achieve the claimed compound. Specifically, the court stated that the prior art compound and the new compound must be similar enough for one to believe they would have the same or similar properties. Teva asserted that lansoprazole, a structurally similar compound used to treat ulcers, would be the "lead compound" from which one of ordinary skill would arrive at rabeprazole. The structures of these two compounds are depicted below, with the differences denoted:

Structural comparisonThe Federal Circuit disagreed that one of ordinary skill in the art would have selected lansoprazole as the lead compound and arrived at rabeprazole. Specifically, the court noted lansoprazole's fluorinated substituent provided a substantial advantage over related compounds in preventing ulcers. As a result, the court stated the record "shows no discernible reason for a skilled artisan to begin with lansoprazole only to drop the very feature . . . that gave this advantageous property." The court then outlined what KSR requires when assessing prior art:

First, KSR assumes a starting reference point or points in the art, prior to the time of invention, from which a skilled artisan might identify a problem and pursue potential solutions. Second, KSR presupposes that the record up to the time of invention would give some reasons, available within the knowledge of one of skill in the art, to make particular modifications to achieve the claimed compound. Third, the Supreme Court's analysis in KSR presumes that the record before the time of invention would supply some reasons for narrowing the prior art universe to a "finite number of identified, predictable solutions."
The court added that when an art is "unpredictable, as the chemical arts often are," the "identified, predictable solutions" aspect of KSR "may present a difficult hurdle because potential solutions are less likely to be genuinely predictable." Based on this analysis, the court held there was insufficient evidence to produce a genuine issue of material fact regarding obviousness. Thus, the court affirmed the district court's ruling.The court then moved on to the claims of inequitable conduct. The defendants had collectively asserted five bases of inequitable conduct against Eisai: failing to disclose a co-pending application and rejections of that application, failing to disclose a prior art patent, submitting a misleading declaration, and concealing lansoprazole from the examiner. The court addressed each in turn.With regard to the copending application and its rejections, while the court stated it would have been "prudent" for Eisai to disclose the co-pending application to the USPTO, it was not a fatal decision because the materiality of that patent was low and there was not specific intent to deceive the USPTO. As for the failure to disclose a specific prior art reference, both the district court and the Federal Circuit stated that the prior art at issue was cumulative to the already-disclosed art, and therefore not material to the prosecution of the patent. Turning to the allegedly misleading declaration, the court stated that the declaration was highly material as it discussed the properties of rabeprazole, but it was not misleading as drafted. The declaration compared rabeprazole to a specific prior art compound cited by the examiner, and therefore "Eisai had no obligation to include additional, unnecessary data" such as a comparison to other prior art compounds. Further, there was no intent to deceive the USPTO in the submission of the declaration, so there was no inequitable conduct. Finally, the court once again did not find any deceptive intent on the part of Eisai in not disclosing lansoprazole to the examiner. The only evidence Dr. Reddy's and Teva relied on was one comment made by an Eisai "insider" saying that the similarity of lansoprazole to rabeprazole bothered him. The court held that this was not sufficient to make this matter material, and certainly not enough to show intent to deceive. As a result, the court again affirmed the district court's findings on inequitable conduct.For the full decision in Eisai Co. v. Dr. Reddy's Labs., Ltd., click here.


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