Corporate Counsel Daily, Stevia patents properly rejected for inadequate written description and lack of patentability, (Jan 3, 2024)

By Robert B. Barnett Jr., J.D.

The Federal Circuit reiterates that the laws of nature are not patentable.

The Federal Circuit has affirmed a lower court ruling that rejected two patents for producing a non-caloric sweetener known as Rebaudioside M or Rebaudioside X because (1) all claims of one patent and the first 13 claims of the other patent were invalid for lack of written description given that the structural features common to the members of the genus were insufficiently disclosed to allow those skilled in the art to visualize or recognize the members of the genus and (2) the remaining claim of the second patent (claim 14) was unpatentable given that it described a process that occurs in nature in stevia plants, which convert Rebaudioside D to Rebaudioside X. The fact that the patent described a process for producing far more Rebaudioside X than the stevia plants could produce did not save the patent because the 50% completion rate that the patent promised was itself an abstract idea lacking the required specificity for achieving the result (PureCircle USA Inc. v. SweeGen, Inc., January 2, 2024, Dyk, T.).

Background. PureCircle USA Inc. and PureCircle Sdn Bhd own patents 9,243,273 (“the ’273 patent”) and 10,485,257 (“the ’257 patent”), which describe a process for developing non-caloric sweeteners (steviol glycoside) called Rabaudioside X or Rebaudioside M. Those compounds occur in nature in stevia plants, but the amount that they produce is so small that extraction from the stevia plants to produce sufficient quantities of the compounds would be prohibitively expensive. Thus, PureCircle developed its process for producing Rabaudioside X or Rebaudioside M in much larger quantities and obtained patents for it.

PureCircle then sued SweeGen, Inc. and Phyto Tech Corp. in California federal district court, asserting patent infringement. The district court granted summary judgment to SweeGen and Phyto Tech, ruling that (1) all claims from both patents were invalid for a lack of written description and (2) claims 1-11 and 14 of the ‘273 patent and claims 1-5 of the ‘257 were unpatentable because they described a naturally occurring process. PureCircle appealed the decision to the Federal Circuit in Washington, D.C.

Written description. Federal patent law requires that a patent’s specifications be written to “clearly allow persons of ordinary skill in the art to recognize that [the inventor] invented what is claimed” (35 U.S.C. §112(a) and Ariad Pharms., Inc. v. Eli Lily & Co., 598 F.3d 1336, 1351 (Fed. Cir. 2010)). Thus, in the context of a genus claim, written description requires the disclosure of either a representative number of species failing within the scope of the genus or structural features common to the members of the genus so that one of skill in the art can visualize or recognize the members of the genus. The appellate court agreed with the lower court that these two patents were to be construed as genus claims (a genus of UDP-glucosyltransferases [UGT] enzymes) using functional language.

The Federal Circuit agreed with SweeGen that the two patents were invalid because they did not disclose a representative number of species or common structural features of the claimed genus to identify which enzymes would function to convert Rabaudioside D to Rebaudioside X at a 50% completion level or higher. The claims, as written, cover at least one trillion enzymes that could potentially perform that function. If properly written, because only one enzyme was disclosed, the patent should have disclosed only a representative number of species. The appellate court also accepted SweeGen’s argument that the potentially trillions of enzymes could have been drastically reduced because the large number of mutations from the only five enzymes capable of steviol glycoside synthesis could be determined with reasonable certainty through homology modeling.

The appellate court also rejected PureCircle’s argument that disclosure of a single enzyme satisfied the written description requirement because it was representative of the genus. While a single example can provide written description support for a genus, the Federal Circuit acknowledged, it will not provide such support unless the specification provides the required “blaze marks.” Even if homology modeling reduced the possibilities, the appellate court said, a person of ordinary skill in the art would still have to undertake “extensive trial and error testing” to identify potential active candidates. Such extensive effort, the Federal Circuit concluded, is further evidence that the written description was inadequate. Thus, the Federal Circuit ruled, “in order for the disclosed species to be representative of the genus, it has to provide blaze marks that would allow a POSA [person of ordinary skill in the art] to identify other members of the genus.” In the absence of such blaze marks here, the appellate court concluded, the patent failed to provide sufficient written description. To put it another way, the court said, “the one enzyme disclosed in the patents here has not been shown to be typical of the entire genus of UGTs claimed.”

Patentability. PureCircle next argued that, even if the written description in claims 1-13 of the ‘273 patent was inadequate, the written description in claim 14 of the ‘273 patent was sufficient because it named a specific enzyme (UGT76G1). Thus, through homology modeling, only 1,800 possible mutations would be involved. The Federal Circuit ruled, however, that it need address whether claim 14 contained an adequate written description because claim 14 was unpatentable under 35 U.S.C. §101.

First, the Federal Circuit noted, the laws of nature are not patentable. This patent, the court noted, claims a natural phenomenon because the enzyme is found in stevia plants, which naturally convert Rabaudioside D or Rebaudioside X. PureCircle argued, on the other hand, that its patent was valid because it involves a completion rate of at least 50%, significantly higher than the stevia plant’s completion rate. The Federal Circuit, however, rejected the argument on the ground that the claim of a 50% completion rate was itself an abstract idea. Section 101 requires that an invention have sufficient specificity to transform a claim of a result to a claim of a way of achieving the result (SAP Am., Inc. v. InvestPic, LLC, 898 F.3d 1161, 1167 (Fed. Cir. 2018)). Under these facts, the appellate court agreed with the lower court that claim 14 “simply states a result, conversion of Reb D to Reb X wherein the conversion is at least about 50% complete.” The claim otherwise provides no steps or guidance for how to achieve a 50% conversion other than a direction to use a natural enzyme. As the result, the Federal Circuit ruled, claim 14 was “invalid as directed to unpatentable subject matter.”

The Federal Circuit thus affirmed the lower court ruling that SweeGen and Phyto Tech were entitled to summary judgment.

The Case is No. 22-1946.

Attorneys: Stanley Joseph Panikowski, III (DLA Piper US LLP) for PureCircle USA Inc. John Christopher Rozendaal (Sterne Kessler Goldstein & Fox PLLC) for SweeGen, Inc. and Phyto Tech Corp. d/b/a Blue California.

Companies: PureCircle USA Inc.; SweeGen, Inc.; Phyto Tech Corp. d/b/a Blue California

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