By Donald Zuhn --
The Federal Circuit today affirmed a determination by the District Court for the District of Delaware that U.S. Patent No. 5,583,122 was not invalid as obvious nor invalid for obviousness-type double patenting. The '122 patent, which is owned by Plaintiff-Appellee Procter & Gamble Co. (P&G), relates to the compound risedronate, which is the active ingredient in P&G’s osteoporosis drug Actonel®. Risedronate is a member of a class of compounds known as bisphosphonates, which are active in inhibiting bone resorption.
After Defendant-Appellant Teva Pharmaceuticals USA, Inc. notified P&G of its intent to market a generic version of risedronate, P&G filed suit against Teva for patent infringement. In response, Teva argued that the '122 patent was invalid as obvious in view of P&G's expired U.S. Patent No. 4,761,406, and alternatively, that the '122 patent was invalid for obviousness-type double patenting. The '406 patent relates to an intermittent dosing method for treating osteoporosis, which allows bisphosphonates to be used in the treatment of osteoporosis without the unwanted side effect of anti-mineralization. The '406 patent specifies 36 bisphosphonates for use in the claimed method, eight of which are preferred compounds, and one of which is the compound 2-pyr EHDP. Teva argued that the disclosure of 2-pyr EHDP in the '406 patent rendered the claims of the '122 patent obvious (risedronate and 2-pyr EHDP are positional isomers, with risedronate having a hydroxy-ethane-diphosphonate group connected to the #3 carbon of its pyridine ring, and 2-pyr EHDP having the hydroxy-ethane-diphosphonate group connected to the #2 carbon).
After a bench trial, the District Court determined that the '406 patent would not have led a person of ordinary skill in the art to identify 2-pyr EHDP as a lead compound, the skilled artisan would not have been motivated to modify 2-pyr EHDP to generate risedronate (at left), and unexpected results of risedronate's potency and toxicity rebutted Teva's assertion of obviousness. As a result, the District Court found the claims of the '122 patent to be non-obvious. The District Court also determined that the '122 patent was not invalid for obviousness-type double patenting.
The Federal Circuit began its analysis by first noting that the evidence of record did not establish that it would have been obvious to modify 2-pyr EHDP to create risedronate, and therefore, that the Court did not need to reach the question of whether the '406 patent would have led a skilled artisan to identify 2-pyr EHDP as a lead compound. The panel noted that Dr. Herbert Fleisch, a preeminent authority on bisphosphonates during the relevant time period, wrote in 1984 that "every compound, while remaining a bisphosphonate, exhibits its own physical-chemical, biological and therapeutic characteristics, so that each bisphosphonate has to be considered on its own," and thus, "[t]o infer from one compound the effects in another is dangerous and can be misleading." The Federal Circuit therefore determined that the District Court had not erred in finding that a person of ordinary skill would not have been motivated to synthesize and test risedronate, and would not have had a reasonable expectation of success in synthesizing and testing risedronate. Moreover, the panel determined that there was no credible evidence that the structural modification of 2-pyr EHDP would have been routine. Thus, the Federal Circuit concluded that the District Court did not clearly err in finding that Teva had failed to establish a prima facie case of obviousness.
Notwithstanding Teva's failure to establish a prima facie case of obviousness, the Federal Circuit also determined that P&G had introduced sufficient evidence of unexpected results. Among these unexpected results were risedronate's potency at low doses and lack of toxicity at higher doses than 2-pyr EHDP could be safely used. The Federal Circuit also determined that the District Court had not erred in considering evidence that risedronate had satisfied a long-felt but unmet need.
With respect to the issue of obviousness-type double patenting, the Federal Circuit determined that the District Court had correctly found the '406 patent to be prior art to the '122 patent, since P&G's evidence that risedronate had been synthesized in May of 1985 was uncorroborated (i.e., laboratory notebook pages describing the synthesis were unwitnessed). The panel noted that "the obviousness analysis applies to double patenting," with the exception that non-statutory double patenting compares claims in an earlier patent to claims in a later patent or application, double patenting does not require inquiry into a motivation to modify the prior art, and double patenting does not require inquiry into objective criteria suggesting non-obviousness. Thus, because risedronate was deemed to be non-obvious in view of the '406 patent, the Federal Circuit concluded that the '122 patent was also not invalid for obviousness-type double patenting in view of the '406 patent. In addition, the panel determined that Teva failed to present clear and convincing evidence of overlap between the claims of the '122 patent (directed to compounds, including risedronate) and the '406 patent (directed to an intermittent dosing regimen, with no compound claims).
Panel: Circuit Judges Mayer and Dyk, and District Judge Huff
Opinion by District Judge Huff