Plexxikon Inc. v. Novartis Pharmaceuticals Corporation

Background

Plexxikon accused Novartis Pharmaceuticals Corporation’s drug Tafinlar® of infringing U.S. Patent Nos. 9,469,640 and 9,844,539. Both patents claim priority to a provisional patent application filed on July 17, 2007. In its infringement contentions, Plexxikon identified March 10, 2005, as the priority date for the asserted claims and produced documents supporting that date.

Plexxikon later referred in a supplemental interrogatory response to draft patent applications prepared before dates associated with Novartis’s prior-art references. But Plexxikon did not amend its infringement contentions to identify another specific priority date. In his March 14, 2019 rebuttal report, Dr. Michael L. Metzker supported the March 2005 priority date and also offered February 2, 2007, as an alternative date by which the inventors had conceived the claimed inventions.

Novartis moved to strike the portions of the report concerning the February 2, 2007 date. Novartis argued that Plexxikon had failed to disclose that alternative theory and the supporting documents in its infringement contentions, as required by the Northern District of California’s Patent Local Rules. Plexxikon argued that it had disclosed the earliest possible priority date, that the later date merely responded to Novartis’s prior-art arguments, and that Novartis was not prejudiced because the draft applications had been produced during discovery. At the hearing, Plexxikon also argued that attorney-client privilege justified its delayed disclosure.

Court’s analysis

The court held that Patent Local Rules 3-1(f) and 3-2(b) require a patent plaintiff to identify the specific priority date for each asserted claim and produce documents evidencing conception, reduction to practice, design, and development created on or before that identified date. The rules do not permit a plaintiff to disclose only the earliest possible date and later introduce an undisclosed range of alternative dates.

The court reasoned that the rules are intended to make the parties’ theories clear early in the case. Plexxikon’s supplemental discovery response did not clearly identify February 2, 2007, as an alternative priority date, and Novartis was not required to infer Plexxikon’s changing theory from documents or indirect references. Because Plexxikon had not amended its infringement contentions, it could not use the rebuttal expert report, served after fact discovery closed, to introduce the new date. The court found that the resulting prejudice was apparent because Novartis had selected prior art and pursued discovery based on the disclosed March 10, 2005 date.

The court also declined to consider Plexxikon’s privilege-based argument as a basis for denying the motion because Plexxikon first raised that argument at oral argument, depriving Novartis of an opportunity to respond. The court added that, even if considered, the argument would not justify an exception to the early-disclosure requirements.

Ruling

Judge Haywood S. Gilliam, Jr. granted Novartis’s motion to strike. The court struck the portions of Dr. Metzker’s rebuttal report that contained or referred to a February 2, 2007 priority date. The court further precluded Plexxikon from arguing that the asserted claims were entitled to a priority date earlier than July 17, 2007, other than the properly disclosed March 10, 2005 date.