Plexxikon Inc. v. Novartis Pharmaceuticals Corporation

Background

Plexxikon brought a patent-infringement action against Novartis concerning U.S. Patent Nos. 9,469,640 and 9,844,539. Plexxikon accused Novartis’s melanoma cancer drug Tafinlar of infringement. The patents cover a class of molecular compounds that inhibit B-Raf kinase.

Novartis moved for partial summary judgment, asking the court to hold that certain claims were invalid as anticipated under 35 U.S.C. § 102. A claim is anticipated when an earlier reference or invention contains all of the claim’s required features. The dispute focused on the patents’ priority date—the date that determines whether the asserted inventions predated the material Novartis relied on.

Plexxikon claimed a March 2005 priority date, even though the provisional patent application was not filed until July 17, 2007. Plexxikon relied mainly on a March 15, 2005 email from co-inventor James Tsai discussing a “new scaffold,” including a phenyl ring with a sulfonamide, fluorine, and a variable “X.” The inventors interpreted “Chao’s first suggestion at X” of “Pyr” as a pyridine, which is a single-ring heteroaryl group. Plexxikon also relied on compounds synthesized in March 2005, December 2006, and January 2007.

The court noted that Plexxikon had also argued for a February 2, 2007 priority date, but an earlier order striking expert testimony supporting that theory disposed of it.

Legal standard and arguments

Summary judgment is proper only when there is no genuine dispute about a material fact and the moving party is entitled to judgment under the law. The court must view the evidence favorably to the party opposing the motion.

For chemical inventions, conception—the formation of a definite and permanent idea of the complete invention—requires both an understanding of the compound’s structure and possession of an operative method for making it. Conception must include every limitation of the patent claim. The court explained that conception of one species, meaning one particular compound, may establish priority for a genus, meaning a broader claimed group of compounds, when the evidence fairly suggests the claimed subject matter without extensive experimentation.

Novartis argued that Plexxikon’s evidence did not show conception of the monocyclic heteroaryl group or the other variables in the claims. Novartis also argued that conception of a species could not establish priority for the claimed genus without evidence of broader applicability. Plexxikon responded that the March 2005 email, inventor declarations, expert opinions, and related documents showed conception of species within the claims and a preference for the claimed groups. Plexxikon also offered expert evidence that methods for making compounds with a direct bond instead of a linker were within routine knowledge.

The court held that patent-office decisions applying Rule 131, an administrative procedure for attempting to establish an invention date before a cited reference, did not directly govern this district-court litigation. The court nevertheless considered the underlying principles relevant to whether the evidence showed complete conception.

Court’s analysis and ruling

The court found that Novartis did not dispute that the March 2005 email showed several claimed features, including the phenyl ring, sulfonamide, fluorine, and a hydrogen at one variable. The email also identified a pyridine as a possible “X” group, and Novartis’s expert did not dispute that pyridine satisfied the claimed aryl-group limitation. The email’s statement that the ketone linker did not need to remain could also suggest a direct bond.

The court concluded that a reasonable jury could find that the email showed conception of species meeting most claim limitations and showed a preference for “X” groups within the claims. The court also found that Novartis had not shown that the proposed methods for making the relevant compounds were insufficient for the species shown in the email.

On the genus issue, the court concluded that Novartis had not shown that determining the full scope of the claims or the equivalence of alternative elements would require more than ordinary skill or extensive experimentation. The evidence plausibly suggested that the inventors had a settled idea and a particular solution involving a single-ring group replacing an azaindole in the scaffold.

The court therefore found that Plexxikon had met its burden of producing evidence supporting conception of a species and that the evidence could support conception of the claimed genus. Because factual disputes remained concerning the patents’ priority date, the court DENIED Novartis’s motion for summary judgment of anticipation. Judge Haywood S. Gilliam, Jr. signed the order.