Docket No. 2012-1228
LOURIE, PROST, MOORE
July 2, 2012
Brief Summary: The clear and convincing burden of proof to show patent invalidity is not changed if the PTO considered the references during prosecution, but such references may have more or less evidentiary weight depending on the particular case.
Summary: Shionogi markets an extended-release tablet of metformin (Fortamet) for which Lupin submitted an ANDA. Shionogi obtained a preliminary injunction from the DC to stop Lupin from selling Fortamet. The dispute focused on U.S. Patent Nos. 6,866,866 (“Controlled Release Metformin Compositions”) which claims dosage forms with “a mean time to maximum plasma con- centration (Tmax) of the drug which occurs at 5.5 to 7.5 hours after oral administration on a once-a-day basis to human patients” (and other claims with more narrow ranges). During prosecution, the Examiner rejected some claims as obvious and those claims were cancelled but ultimately issued, even though the supplemental notice of allowance indicated that claims having an upper limit of 7.5 hours were cancelled. In granting the preliminary injunction, the DC rejected Lupin’s arguments that the claims were improperly issued, did not reach the merits of the obviousness arguments, and noted “the very steep requirement that the Defendant show clear and convincing evidence of the invalidity of Plaintiff’s patent.” In Feb. 2012, the FC vacated that decision and remanded it for consideration of Lupin’s obviousness arguments. Later that month, the DC again found for Shionogi, in large part because the PTO had already considered the references alleged to render the claims obvious (citing Pharmastem, FC 2007 (“added burden of overcoming the deference that is due to a qualified government agency presumed to have done its job”)). The FC panel pointed out, however, that whether a reference was considered does not change the clear and convincing evidentiary burden to show invalidity even though evidence not previously considered “may carry more weight” (citing Microsoft, US 2011). The panel concluded that Lupin had raised a substantial question of validity as the references disclosed all the limitations of the claims except for the Tmax range of 5.5 to 7.5 hours (disclosed Tmax of 8 to 12 hours (as admitted by the ‘866 patent) and 4.67 to 6.33 hours) and the motivation to modify the claimed range. Thus, the preliminary injunction was vacated and the case remanded for further proceedings.