I. BACKGROUND
The ’122 patent claims the compound risedronate, the active ingredient of P&G’s osteoporosis drug Actonel®. In August 2004, P&G sued Teva for infringement of the ’122 patent after Teva notified P&G that it planned to market risedronate as a generic equivalent of Actonel®. Specifically, P&G alleged that Teva’s proposed drug infringed claim 4 of the ’122 patent for the compound risedronate, claim 16 for pharmaceutical compositions containing risedronate, and claim 23 for methods of treating diseases using risedronate. In its defense, Teva argued that the ’122 patent was invalid as obvious in light of P&G’s expired U.S. Patent 4,761,406 (the “’406 patent”), filed on June 6, 1985 and issued on August 2, 1988. Alternately, Teva argues that the ’122 patent is invalid for obviousness-type double patenting.
Risedronate, the subject of the contested claims, is a member of a group of compounds referred to as bisphosphonates. Bisphosphonates, in general, are active in inhibiting bone resorption. The first two promising bisphosphonates studied for the treatment of metabolic bone diseases, etidronate (EHDP) and clodronate, had clinical problems which prevented their commercialization. P&G conducted a significant amount of experimentation involving hundreds of different bisphosphonate compounds, but could not predict the efficacy or toxicity of the new compounds. Eventually, researchers at P&G identified risedronate as a promising drug candidate.

On December 6, 1985, risedronate’s inventors applied for a patent on the compound. P&G is the owner by assignment of the ’122 patent, entitled “Pharmaceutical Compositions Containing Geminal Diphosphonates,” which issued on December 10, 1996.

Risedronate is neither claimed nor disclosed in the ’406 patent. Instead, the ’406 patent, entitled “Regimen for Treating Osteoporosis,” claims an intermittent dosing method for treating osteoporosis. As the trial court noted, the ’406 patent “addresses the central problem seen in bisphosphonates at the time, namely that they inhibited bone mineralization, by teaching the use of a cyclic administrative regimen to achieve a separation of the benign effect of anti-resorption from the unwanted side effect of anti-mineralization in patients.” Procter & Gamble, 536 F. Supp. 2d at 492. The ’406 patent lists thirty-six polyphosphonate molecules as treatment candidates and eight preferred compounds for intermittent dosing, including 2-pyr EHDP. Teva contends that the structural similarities between risedronate and 2-pyr EHDP render the challenged claims of the ’122 patent obvious.

From the testimony at trial, the district court concluded that the ’406 patent would not have led a person of ordinary skill in the art to identify 2-pyr EHDP as the lead compound. In light of the extremely unpredictable nature of bisphosphonates at the time of the invention, the district court also found that a person of ordinary skill in the art would not have been motivated to make the specific molecular modifications to make risedronate. The district court concluded that unexpected results of risedronate’s potency and toxicity rebut a claim of obviousness. The district court found that secondary considerations of non-obviousness supported its conclusions. Similarly, the court found that the ’122 patent was not invalid for obviousness-type double patenting. 2008-1404, -1405, -1406 3
This consolidated appeal followed. We have jurisdiction pursuant to 28 U.S.C. § 1295(a)(1).

II. DISCUSSION
I.
Standard of Review
“On appeal from a bench trial, this court reviews 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). Whether the subject matter of a patent is obvious is a question of law and is reviewed de novo. PharmaStem Therapeutics, Inc. v. ViaCell, Inc., 491 F.3d 1342, 1359 (Fed. Cir. 2007). Factual determinations underlying the obviousness issue are reviewed for clear error. Alza Corp. v. Mylan Labs., Inc., 464 F.3d 1286, 1289 (Fed. Cir. 2006). The evidentiary burden to show facts supporting a conclusion of invalidity is one of clear and convincing evidence. AK Steel Corp. v. Sollac & Ugine, 344 F.3d 1234, 1238-39 (Fed. Cir. 2003). Non-statutory double patenting is a legal question reviewed without deference. Georgia-Pacific Corp. v. U.S. Gypsum Co., 195 F.3d 1322, 1326 (Fed. Cir. 1999). Next Page ->