United States: Disclosure of Genetically Altered Tobacco Plant Did Not Enable Genetically Altered Tomato Plant

Affirming the decision of the U.S. Patent and Trademark Office (USPTO) in an interference directed to genetically altered, insect-resistant tomato plants, the U.S. Court of Appeals for the Federal Circuit found that disclosure of successful experiments with genetically altered tobacco plants would not have enabled one skilled in the art to produce tomato plants "without undue experimentation." Adang v. Fischhoff, 2002 U.S. App. LEXIS 7220, Case No. 01-1169 (Fed. Cir., April 10, 2002).

On the issue of enablement, the Board of Patent Appeals and Interferences focused on the differences between transformed tobacco plants, which were exemplified in the Adang patent, and transformed tomato plants, which were merely listed along with several other plants as potential subjects of similar genetic transformations. The Board also considered Adang’s own statements made during prosecution concerning unreliability of data obtained in other species of transformed tobacco plants, as well as prior and contemporaneous art disclosing that expression of foreign genes in plants, particularly the Bt gene, was not "straightforward." The Board found that the combination of the inventor’s statements during prosecution and the shortcomings of plant transformation and foreign gene expression noted in the art raised "substantial doubts" that Adang’s disclosure would have enabled one of skill in the art at the time to practice the invention without undue experimentation.

The Federal Circuit, applying the substantial evidence standard, affirmed. The Court noted that Adang’s arguments during prosecution that the cited prior art showing of gene expression obtained in a different strain of tobacco was not predictive of similar expression in the strain Adang used were evidence of the lack of predictability of successful transformation in any given plant. In addition, the expert witness proffered by Adang in the interference testified that gene expression is affected by the particular strain of plant used for the assays. On the basis of these statements, the Court found it "reasonable to conclude that those of skill in the art would not have expected expression in tomato plants to track that in a particular strain of tobacco."

Other evidence reviewed by the Court included prior art publications enumerating problems with plant transformation in obtaining foreign expression of the Bt gene, including the inventor’s own publication reporting problems associated with expression of the Bt gene in a foreign host cell, as well as scientific literature (published within a year of Adang’s filing date) that disclosed repeated failures of others to obtain successful transformation of tobacco plants with the Bt gene.

Practice Note: Historically, genetic engineering of plants, such as gene therapy, has been viewed by the USPTO and courts to be an unpredictable art, based primarily on the vast amount of literature reporting failures and problems associated with gene uptake and expression. However, successful plant genetic engineering results are published almost daily, and such publications should be relied upon during prosecution to counter enablement rejections. Also, as Adang illustrates, statements made during prosecution to distinguish over prior art or in an inventor’s publications should be crafted carefully so as not to negate enablement of broad claims.