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Positional Isomer Not Obvious Where Compounds Are Unpredictable and General Teaching Would Not Have Provided a Reasonable Expectation of Success

May 13, 2009

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Last Month at the Federal Circuit - June 2009

Judges: Mayer, Dyk, Huff (District Judge sitting by designation, author)

[Appealed from: D. Del., Judge Farnan]

In Procter & Gamble Co. v. Teva Pharmaceuticals USA, Inc., Nos. 08-1404, -1405, -1406 (Fed. Cir. May 13, 2009), the Federal Circuit affirmed the district court’s decision that The Procter & Gamble Company’s (“P&G”) claims to a bone resorption inhibitor and related compositions and methods were not invalid for either obviousness or obviousness-type double patenting. P&G is the owner by assignment of U.S. Patent Nos. 5,583,122 (“the ’122 patent”) and 4,761,406 (“the ’406 patent”). The ’122 patent claims a composition and methods relating to a bisphosphonate compound known as risedronate. The ’406 patent, which had previously expired, relates to intermittent dosing regiments for treating osteoporosis and lists thirty-six polyphosphonate molecules as treatment candidates. The ’406 patent further identifies eight preferred compounds for intermittent dosing, including 2-pyr EHDP, but does not disclose or claim risedronate. Risedronate and 2-pyr EHDP are position isomers, meaning that they have similar structures, except that the functional group is positioned at a different location along the pyridinyl ring.

In August 2004, P&G sued Teva Pharmaceuticals USA, Inc. (“Teva”) for infringing various claims of the ’122 patent by marketing a generic version of risedronate under the name Actonel®. Following a bench trial, the district court held that the asserted claims of the ’122 patent were not invalid as obvious in light of the structural similarities between risedronate and the 2-pyr EHDP identified in the ’406 patent. The district court further held that the claims of the ’122 patent directed to risedronate were not invalid due to obviousness-type double patenting over the claims of the ’406 patent, which covered the structurally similar 2-pyr EHDP.

On appeal, the Federal Circuit addressed whether it would have been obvious to modify 2-pyr EHDP to create risedronate. The Court first considered whether a person of ordinary skill in the art would have had “reason to attempt to make the composition” (i.e., risedronate) and “a reasonable expectation of success in doing so.” Noting that such questions often turn on the structural similarities and differences between the claimed compound and the prior art compound, the Court considered the structure of 2-pyr EHDP and risedronate. As 2-pyr EHDP and risedronate are positional isomers, the Court noted that they differed in three-dimensional shape, charge distribution, and hydrogen bonding properties. Thus, the Court questioned whether the prior art would have suggested modifying 2-pyr EHDP to create risedronate. Ultimately, the Court noted that the bisphosphonate compounds, such as 2-pyr EHDP and risedronate, were unpredictable. Accordingly, the Court held that there was insufficient motivation for a person of ordinary skill to synthesize and test risedronate.

Addressing various cases that have applied KSR International Co. v. Teleflex Inc., 550 U.S. 398 (2007), the Court next observed that, when a person of ordinary skill is faced with a finite number of identified, predictable solutions to a problem and pursues the known options within his or her technical grasp, the resulting discovery is likely the product not of innovation but of ordinary skill and common sense. On the other hand, the Court recognized that in other cases, researchers can only vary all parameters or try each of numerous possible choices until one possibly arrives at a successful result, where the prior art gives either no indication of which parameters are critical or no direction as to which of many possible choices is likely to be successful. In such cases, the Court warned against applying hindsight to render a patent invalid. With respect to risedronate, the Federal Circuit concluded that Teva had presented no credible evidence that a structural modification of 2-pyr EHDP to create risedronate would have been routine. Slip op. at 10. Accordingly, the Federal Circuit concluded that the district court did not clearly err in finding that Teva had not established a prima facie case of obviousness for the ’122 patent.

Despite holding that Teva had not presented a prima facie case of obviousness, the Court nevertheless considered P&G’s nonobviousness arguments. First, the Court concluded that, even had Teva established a prima facie case of obviousness, P&G had “introduced sufficient evidence of unexpected results to rebut any finding of obviousness.” Id. at 12. As for secondary considerations, the Court clarified that it was required to “look to the filing date of the challenged invention to assess the presence of a long-felt and unmet need.” Id. at 13. Thus, because competing products were not available until ten years after the date of invention, those products could not have satisfied the long-felt, unmet need. Accordingly, the Court held that “it was not clear error for the district court to conclude that risedronate met [a long-felt and unmet] need and that secondary considerations supported a finding of non-obviousness.” Id.

The Federal Circuit next rejected P&G’s argument that the ’122 patent could not be held obvious in light of the ’406 patent because risedronate was first synthesized before the ’406 patent was filed, and the ’406 patent was therefore not prior art. Id. at 13-14. The Court concluded that “P&G did not provide adequate corroborating evidence of an earlier invention date for risedronate.” Id. at 14. Rather, P&G had only provided an unwitnessed laboratory notebook entry detailing the structure of risedronate and how to make it. P&G did not provide any other corroborating evidence. As a result, the Federal Circuit agreed with the district court’s conclusion that P&G’s evidence was insufficient to establish inventorship. The Court reasoned that a putative inventor “must provide independent corroborating evidence in addition to his own statements and documents.” Id. (quoting Hahn v. Wong, 892 F.2d 1028, 1032 (Fed. Cir. 1989)). Thus, the ’406 patent was available as prior art for the obviousness analysis.

Finally, the Federal Circuit affirmed the district court’s holding that P&G’s claims at issue were not invalid for obviousness-type double patenting. Id. at 14-15. The Court concluded that Teva “failed to present clear and convincing evidence of overlap between the claims of the two patents.” Id. at 15. Rather, the Court observed that “while claims 4 and 16 of the ’122 patent explicitly claim the risedronate compound, the ’406 patent claims an intermittent dosing regimen for the treatment of osteoporosis and claims no new compounds.” Id. Thus, the Federal Circuit agreed with the district court that “the claims of the ’122 patent are distinct from the claims of the ’406 patent.” Id. at 14-15.

Summary authored by Andrew R. Chadeayne, Ph.D., student associate at Finnegan.