This week, the U.S. Court of Appeals for the Federal Circuit issued an opinion in PureCircle USA Inc. v. Sweegen, Inc., No. 2022-1946 (Jan. 2, 2024), affirming the District Court for the Central District of California’s summary judgment holding that PureCircle’s non-caloric sweetener patents were invalid for lack of adequate written description and as directed to patent-ineligible subject matter.
Rebaudioside X (“Reb X”) is a non-caloric sweetener naturally produced by stevia plants. PureCircle owns U.S. Patent Nos. 9,243,273 and 10,485,257, which claim a method of synthesizing Reb X using a specific class of enzymes, UDP-glucosyltransferases (“UGT”). PureCircle sued Sweegen for infringement, and the district court granted summary judgment that PureCircle’s patents were invalid. PureCircle appealed.
The Federal Circuit affirmed. The Court explained that in the context of chemical genus claims, such as the claims of PureCircle’s patents, the written description requirement “requires the disclosure of either a representative number of species falling within the scope of the genus or structural features common to the members of the genus.” The Court held that PureCircle’s patents did not meet either requirement; the specification only disclosed a single, non-representative example of the claimed UGT enzyme genus and failed to disclose any common structural features of the claimed genus. PureCircle argued that the single disclosed example was representative because it contained structural features common to all UGT enzymes. The Court disagreed, holding that the specification did not disclose these common features in a manner that would permit a person of ordinary skill in the art to recognize the members of the genus without extensive trial-and-error testing. The Court accordingly affirmed the district court’s holding that PureCircle’s patents failed to meet the written description requirement.
The Court likewise affirmed the district court’s holding that certain claims of PureCircle’s patents were directed to unpatentable subject matter under 35 U.S.C. § 101. The Court determined that the claimed enzyme was an unpatentable natural phenomenon because it naturally synthesizes Reb X in stevia plants. PureCircle attempted to distinguish the claims from the naturally occurring process, asserting that stevia plants only produce trace amounts of Reb X, while the claims are directed to at least 50% conversion to Reb X. The Court rejected this argument, holding that the 50% conversion result is still an abstract idea, and that PureCircle’s patents did not disclose how to achieve that result other than by using a naturally occurring enzyme.
