MMUNEX CORPORATION v. SANOFI-AVENTIS U.S. LLC

Before Prost, Reyna, and Taranto. Appeal from the Patent Trial and Appeal Board.

Summary: Expiration of a patent during appeal from IPR does not trigger claim construction under the Phillips standard when the expiration was caused by litigant’s filing of terminal disclaimer and the IPR was filed before the Phillips standard applied in all IPRs.

Sanofi filed inter partes reviews of a patent owned by Immunex. The patent at issue described a “human antibody” for binding to interleukin receptors. Under the broadest reasonable interpretation (“BRI”) standard, the PTAB found that the term “human antibody” included “humanized” antibodies, or antibodies comprising some regions derived from non-human origins. Based on that interpretation, the PTAB invalidated the claims over the cited prior art.

The Federal Circuit acknowledged that today, in all newly filed IPRs, the Board applies the Phillips standard. However, when Sanofi filed its IPRs, the Board only applied this standard to expired patents and applied the BRI standard to unexpired patents. After the parties filed appellate briefs for the IPRs, Immunex filed a terminal disclaimer of its patent, and subsequently, the patent expired before the Federal Circuit heard oral arguments. Immunex argued on appeal that because the patent expired, the Court should construe the terms under the Phillips standard rather than the BRI standard. Though the Federal Circuit acknowledged that it has applied the Phillips standard when a patent expired on appeal, the Court distinguished the present case because the patent term was unexpectedly cut short by Immunex’s terminal disclaimer after the appellate briefing. Construing “human antibody” under the BRI standard, the Court affirmed the PTAB’s finding of invalidity.

Editor: Paul Stewart

Written by: Suyoung Jang & Nicole R. Townes