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The DOE Compensates for the Patentee’s Inability to Claim Unforeseeable New Matter

January 29, 2004

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Last Month at the Federal Circuit - February 2004

Judges: Rader (author), Plager, and Gajarsa

In SmithKline Beecham Corp. v. Excel Pharmaceuticals, Inc., No. 02-1581 (Fed. Cir. Jan. 29, 2004), the Federal Circuit vacated a district court’s SJ of noninfringement because, under the DOE, questions of fact remained concerning the foreseeability of certain time-release agents alleged to be equivalent to a claimed time-release agent when the claims were amended.

SmithKline Beecham Corporation, doing business as GlaxoSmithKline (“GSK”), owns U.S. Patent No. 5,427,798 (“the ‘798 patent”) directed to controlled sustained-release tablets containing bupropion hydrochloride. Bupropion is used to treat depression and addiction, and is marketed for the treatment of depression as Wellbutrin®SR, and as Zyban® for smoking cessation. The ‘798 patent is directed to a sustained-release composition containing hydrogels that swell upon ingestion. The hydrogel described by the ‘798 patent is hydroxypropyl methylcellulose (HPMC).

Many of the original claims of the ‘798 patent did not recite HPMC as a limitation. During prosecution, the Examiner rejected the claims that did not recite HPMC for lack of enablement under 35 U.S.C. § 112, ¶ 1. GSK then amended those claims to overcome the rejection and to recite HPMC.

In response to an ANDA filing, GSK filed suit against Excel Pharmaceuticals, Inc. (“Excel”) for infringement of the ‘798 patent. In Excel’s ANDA filings before the FDA, Excel claimed that the proposed generic substitutes did not infringe the ‘798 patent because the proposed sustained-release compositions contained polyvinyl alcohol (PVA), a hydrogelforming polymer, and did not contain HPMC.

The district court found that there was no literal infringement. Further, citing Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722 (2002) (“Festo VIII”), the district court found that, because the claims had been narrowed in order to comply with § 112, GSK was estopped from asserting infringement under the DOE, and the court granted SJ of noninfringement.

In reviewing the case, the Federal Circuit noted that, according to Festo VIII, not all narrowing amendments surrender subject matter that the DOE cannot later recapture. GSK noted that PVA could not have been added in an amendment at the pertinent time without drawing a new matter rejection, as GSK had not recited any controlled-release agents other than HPMC. Accordingly, it reasoned the Festo presumption was rebutted, and the DOE was justifiably invoked. The Federal Circuit rejected GSK’s arguments, noting that the Festo ruling was meant to reflect whether the applicant would have been expected to know of, and thus properly claim, the proposed equivalent at the time of the amendment.

The record contained some evidence showing that at the time the amendment was made, there were no known hydrogels other than HPMC that had been tested with bupropion to achieve sustained release. Thus, the record suggested that PVA was not a known sustained-release agent, with respect to bupropion, but the record on this issue was not fully developed for SJ purposes. Accordingly, the Court vacated the SJ and remanded.