Naturally occurring compounds generically referred to as steviols are used as sugar substitutes because they impart sweetness without contributing calories. These compounds exist in different forms, with some being sweeter than others. One particular form, referred to as both rebaudioside M and rebaudioside X, is said to be more potent and have a better flavor profile than other steviols. However, rebaudioside X is only a minor component of the stevia plant and, for that reason, it is inefficient to extract it directly.
Along with the family of steviols are a family of enzymes called UDP-glycosyltransferases (UGTs), which are used by stevia plants to synthesize steviols. Using an appropriate UGT, steviols that occur more abundantly in the stevia plant can be converted to rebaudioside X, as claimed by U.S. Patent No. 9,243,273 ("the '273 patent"), e.g.:
1. A method for making Rebaudioside X comprising a step of converting Rebaudioside D to Rebaudioside X using a UDP-glucosyltransferase, wherein the conversion of Rebaudioside D to Rebaudioside X is at least about 50% complete.
14. The method of claim 1, wherein the UDP-glucosyltransferase comprises UGT76G1.
To those familiar with the U.S. Court of Appeals for the Federal Circuit's cases invalidating for lack of written description claims directed to a genus of antibodies, claim 14 would prompt an inquiry along the lines of "how many UGTs are embraced by claim 1?" If the answer were "9,000," inquirers might posit that claim 1 is invalid for lack of written description. And they would be right, as held by the district court on summary judgment and affirmed by the Federal Circuit. PureCircle USA Inc. v. SweeGen, Inc., No. 2022-1946, 2024 WL 20567, *4 (Fed. Cir. Jan. 2, 2024) ("In short, the one enzyme disclosed in the patents here has not been shown to be typical of the entire genus of UGTs claimed. Under such circumstances, there is no adequate written description.").
By now, the reader may be asking "what's 'the one enzyme disclosed in the patents'" and "where is the abstract idea?" The answers are "UGT76G1" and "in dependent claim 14." Clearly, the cause of claim 1's problem with lack of written description – that as many as 9,000 different UGT enzymes might serve the claimed purpose of converting rebaudioside D to rebaudioside X – is absent from claim 14, which requires use of a specific enzyme identified in the specification. And we're told that rebaudioside X is present in stevia plants in trace amounts, indicating that the naturally occurring yield from enzymatic conversion of rebaudioside D to rebaudioside X is less than the 50% claimed.
The "abstract idea" in these claims is the 50% yield itself. One could not claim the enzymatic conversion of rebaudioside D to rebaudioside X by use of UGT76G1 because that is a natural phenomenon: stevia plants themselves convert rebaudioside D to rebaudioside X using UGT76G1, albeit at a yield below 50%. Thus, the claims' requirement of a yield of at least about 50% avoids claiming a natural law.
But according to the Federal Circuit, the yield requirement does not save claim 14 from invalidity under Section 101 because "the 50% completion is itself an abstract idea":
To be eligible under § 101, an invention must have the "specificity required to transform a claim from one claiming only a result to one claiming a way of achieving it." "[I]n the context of claims to results, we have explained that claims that 'simply demand[] the production of a desired result . . . without any limitation on how to produce that result' are directed to an abstract idea." As the district court explained, claim 14 of the '273 patent "d[id] not specify how to achieve a particular purity or conversion percentage; rather, [it] only recite[s] the resulting percentages." Claim 14 simply states a result, conversion of Reb D to Reb X wherein the conversion is at least about 50% complete. The claim does not provide any steps or give guidance as to how to achieve a 50% conversion other than the direction to use a natural enzyme. Claim 14 is directed to subject matter that is a natural phenomenon or abstract idea at step 1 of Alice/Mayo.
Id. at *6 (citations omitted). The court distinguished a case relied on by the patentee in which claims directed to "a compound which existed in nature in quantities higher than natural levels" by reliance on its de facto carve-out from Section 101 of claims directed to "methods of treatment," because such claims "alter[] an individual's natural state." Id. n.11 (distinguishing Natural Alternatives Int'l, Inc. v. Creative Compounds, LLC, 918 F.3d 1338, 1343–44 (Fed. Cir. 2019).
The Federal Circuit did not delve into how – if at all – claim 14 could have been drafted to avoid a Section 101 problem. However, its observation that the "claim does not provide any steps or give guidance as to how to achieve a 50% conversion other than the direction to use a natural enzyme" suggests the potential applicability of claim drafting techniques from the chemical arts, where reaction conditions such as pressure, temperature, pH and the like are often recited along with other details such as stoichiometry, reaction time, and the presence or absence of catalysts, impurities or byproducts.
