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September 9, 2010

Receptor Blocker

Daiichi Sankyo owns 5,616,599, which claims a compound formula (angiotensin receptor blockers "ARBs") used to treat high blood pressure. Research on this line of drugs began in the 1970s. '599 represents an advancement in the second generation of similar compounds. Mylan's ANDA got the litigation ball rolling. With the pressure on, Mylan couldn't convince the district court, in a 10-day bench trial, that '599 was obvious. The pressure stayed on in appeal.

Daiichi Sankyo v. Matrix Laboratories and Mylan (CAFC 2009-1511) precedential

The CAFC applauded the district court's opinion as "comprehensive and well-reasoned."

Under the Patent Act, "[a] patent may not be obtained . . . if the differences between the subject matter sought to be patented and the prior art are such that the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art to which said subject matter pertains." 35 U.S.C. § 103(a). While the ultimate determination of obviousness under § 103 is a question of law, it is based on several underlying factual findings, including (1) the scope and content of the prior art; (2) the level of ordinary skill in the pertinent art; (3) the differences between the claimed invention and the prior art; and (4) evidence of secondary factors, such as commercial success, long-felt need, and the failure of others. Graham v. John Deere Co., 383 U.S. 1, 17-18 (1966). After a bench trial, we review the district court's conclusions of law de novo and findings of fact for clear error. Golden Blount, Inc. v. Robert H. Peterson Co., 365 F.3d 1054, 1058 (Fed. Cir. 2004). A factual finding is clearly erroneous if, despite some supporting evidence, a reviewing court is left with the definite and firm conviction that a mistake has been made. United States v. U.S. Gypsum Co., 333 U.S. 364, 395 (1948).

Obviousness in a chemical compound case depends upon motivation select and modify a prior art compound "to arrive at a claimed compound with a reasonable expectation that the new compound would have similar or improved properties compared with the old."

When a patent claims a chemical compound, a prima facie case of obviousness under the third Graham factor frequently turns on the structural similarities and differences between the compounds claimed and those in the prior art. In re Dillon, 919 F.2d 688, 692 (Fed. Cir. 1990) (en banc) ("This court . . . reaffirms that structural similarity between claimed and prior art subject matter, proved by combining references or otherwise, where the prior art gives reason or motivation to make the claimed compositions, creates a prima facie case of obviousness."); see also Eisai Co. Ltd. v. Dr. Reddy's Labs., Ltd., 533 F.3d 1353, 1356-57 (Fed. Cir. 2008). Proof of obviousness based on structural similarity requires clear and convincing evidence that a medicinal chemist of ordinary skill would have been motivated to select and then to modify a prior art compound (e.g., a lead compound) to arrive at a claimed compound with a reasonable expectation that the new compound would have similar or improved properties compared with the old. Eisai, 533 F.3d at 1357; Takeda Chem. Indus., Ltd. v. Alphapharm Pty., Ltd., 492 F.3d 1350, 1356 (Fed. Cir. 2007). In keeping with the flexible nature of the inquiry after KSR International Co. v. Teleflex Inc., 550 U.S. 398 (2007), the motivation to select and modify a lead compound need not be explicit in the art. Eisai, 533 F.3d at 1357; Takeda, 492 F.3d at 1356-57.

The failure of obviousness was lack of motivation, both in selecting the lead compound (the prior art "'902 ARBs"), and in modifying that compound to synthesize the claimed invention (olmesartan medoxomil).

Mylan argues that because the '902 ARBs are undisputedly the closest prior art, that "should have been dispositive of the lead compound issue." Appellant Principal Br. 25. That argument runs contrary to our case law. In Takeda, we upheld a district court's finding that one of skill in the art would not have chosen the structurally closest prior art compound, compound b, as the lead compound in light of other compounds with more favorable characteristics. 492 F.3d at 1357-59. We reached the same result in Eli Lilly & Co. v. Zenith Goldline Pharmaceuticals, Inc., 471 F.3d 1369, 1377-79 (Fed. Cir. 2006). These cases illustrate that it is the possession of promising useful properties in a lead compound that motivates a chemist to make structurally similar compounds. Yet the attribution of a compound as a lead compound after the fact must avoid hindsight bias; it must look at the state of the art at the time the invention was made to find a motivation to select and then modify a lead compound to arrive at the claimed invention. See Ortho-McNeil Pharm., Inc. v. Mylan Labs., Inc., 520 F.3d 1358, 1364 (Fed. Cir. 2008). Accordingly, proving a reason to select a compound as a lead compound depends on more than just structural similarity, but also knowledge in the art of the functional properties and limitations of the prior art compounds. See Eli Lilly, 471 F.3d at 1377-79. Potent and promising activity in the prior art trumps mere structural relationships.

While the lead compound analysis must, in keeping with KSR, not rigidly focus on the selection of a single, best lead compound, see Altana Pharma, 566 F.3d at 1008, the analysis still requires the challenger to demonstrate by clear and convincing evidence that one of ordinary skill in the art would have had a reason to select a proposed lead compound or compounds over other compounds in the prior art.

The district court found, and the CAFC agreed, that the prior art taught away from achieving what '599 claimed.

Affirmed.

Posted by Patent Hawk at September 9, 2010 6:09 PM | Prior Art

Comments

Showing an offensive lineman is itself "offensive".

Clearly, a "Receptor Blocker" would be a cornerback or even a safety.

Patent Hawk, is it safe to assume that you were a band geek?

Posted by: Pedantic Pete at September 10, 2010 4:05 AM