Adang v. Fischhoff

Applicant Loses Priority Given Nonenabling Disclosure of Interference Count


April 10, 2002


Last Month at the Federal Circuit - May 2002

Judges: Linn (author), Gajarsa, and Friedman

In Adang v. Fischhoff, No. 01-1169 (Fed. Cir. Apr. 10, 2002), the Federal Circuit reversed the Board’s construction of count 1 of U.S. Patent Application No. 06/848,733, filed by Dr. Michael J. Adang and Dr. John D. Kemp (collectively “Adang”). The Court also affirmed the Board’s determination that the application is nonenabling, even under the correct count construction, and, thus, is not determinative of priority.

This interference concerns tomato plants that have been genetically modified to incorporate a bacterial gene derived from the bacterium Bacillus thuringiensis (“Bt”) that confers insect resistance. The bacterium produces proteins as a protoxin, or inactive form, with a molecular weight of 130 kD. The activated toxin form of the protein, which is toxic to certain insects, has a molecular weight of 67 kD. The procedure for modifying the tomato plants is as follows: The Bt gene is isolated from the bacterium and inserted in a modified plasmid derived from a separate bacterium, Agrobacterium tumefaciens. (Plasmids are small loops of DNA that can be used to transfer a gene of interest between biologic systems.) After the modified plasmid bearing the Bt gene has been produced, it is returned to the Agrobacterium, and this modified bacteria is then brought into contact with tomato cells. The cells are incubated together with the bacteria to produce transformed cells, which are cultured to create regenerated tomato plants that produce a Bt crystal protein.

On June 10, 1991, Adang filed Application No. 07/713,624 (“Adang ‘91”) entitled “Insect Resistant Plants” and directed to the above invention, claiming benefit of the October 21, 1988, filing date of CIP Application No. 07/260,574 (“Adang ‘88”); the April 4, 1986, filing date of CIP Application No. 06/848,733 (“Adang ‘86”); and the September 26, 1983, filing date of Application No. 06/535,354 (“Adang ‘83”).

On December 23, 1991, Dr. David A. Fischhoff and Dr. Stephen G. Rogers (collectively “Fischhoff”) filed Application No. 07/813,250 (“Fischhoff ‘91”) entitled “Insect Resistant Tomato Plants,” claiming benefit of the November 20, 1986, filing date of Application No. 06/932,818 (“Fischhoff ‘86”). An APJ declared this interference between the subject matter claimed in Adang ‘91 and Fischhoff ‘91. Count 1 of the interference reads as follows:

A tomato plant which has been regenerated from a tomato plant cell transformed to comprise a full length Bacillus thuringiensis crystal protein gene capable of encoding a Bacillus thuringiensis crystal protein of about 130 kD under control of a promoter such that said gene is expressible in said plant in amounts insecticidal to Lepidopteran insects.

The APJ accorded Adang benefit of the October 21, 1988, filing date of Adang ‘88, and the April 4, 1986, filing date of Adang ‘86, and accorded Fischhoff benefit of the November 20, 1986, filing date of Fischhoff ‘86.

In its final decision in the interference, the Board construed Count 1 to require that “the tomato plants must produce Bt crystal protein having a molecular weight of ~130 kD in amounts sufficient to destroy or control Lepidopteran insects.” The Federal Circuit noted that, under the Board’s construction, the toxic effects must be directly attributable to “Bt crystal protein protoxin of about 130 kD” that is actually produced by the transformed plants in “amounts . . . which destroy or control Lepidopteran insects in any way.”

In light of this construction, the Board considered whether Adang should be accorded the benefit of the April 4, 1986, filing date of Adang ‘86. In answering this question, the Board considered both the adequacy of the written description of Adang ‘86 and whether that disclosure was enabled. The Board found that Adang ‘86 contained an adequate written description, but lacked an enabling disclosure. Relying on several sources of evidence, the Board found that transforming tobacco plant cells, which were the subject of the embodiments of Adang ‘86, to express a full-length Bt crystal protein gene was so rare and unpredictable that the skilled artisan would not reasonably have expected to be able to successfully transform tomato-plant cells, which were merely listed in the patent disclosure along with numerous other plants, in a similar fashion.

Lastly, the Board found that Adang had not established a priority date earlier than November 20, 1986, the filing date of Fischhoff ‘86, based either on actual reduction to practice or prior conception plus diligence in reduction to practice.

The Federal Circuit held that the Board had erred in its construction of Count 1 requiring that the transformed tomato plants of the count “must produce amounts of Bt crystal protein protoxin of about 130 kD which destroy or control Lepidopteran insects in any way” (emphasis added). The Court then stated the proper count construction of Count 1. According to the Court, tomato plants encompassed by Count 1 (1) must have been regenerated from a tomato-plant cell transformed by a full-length, Bt crystal protein gene that encodes Bt crystal protein of about 130 kD under control of a promoter that directs expression of said structural gene in said tomato-plant cell; and (2) must produce amounts of a Bt crystal protein of any size that destroy or control Lepidopteran insects in any way.

However, the Federal Circuit affirmed the Board’s conclusion that Adang ‘86 did not enable Count 1, even under the Court’s correct count construction, and that Adang was, therefore, not entitled to claim priority to the April 4, 1986, filing date of that application. Examining the references relied upon by the Board, the Court agreed that the disclosure of a successful transformation of tobacco plants using a fulllength Bt crystal protein gene and insect toxicity of those plants would not have enabled the skilled artisan at the time to successfully conduct a similar transformation of an entirely different species, such as tomato, without undue experimentation.

The Federal Circuit noted that since Adang ‘86 is nonenabling, Adang’s case for priority of invention of Count 1 rests on an ability to show either actual reduction to practice of an embodiment of the count prior to November 20, 1986, the filing date of Fischhoff ‘86, or conception of an embodiment of the count prior to that date and diligence in reducing the embodiment to practice. The Court remanded this matter to the Board for further consideration of the issue of priority since the factual findings of the Board were insufficient to determine whether Adang had sustained his burden of proof on this issue.