Federal Circuit Rules on Enablement and Written Description in Two Biotech Cases

Article by Paul Devinsky and Krista Vink Venegas

In the first of two recently decided biotech cases where the U.S. Court of Appeals for the Federal Circuit had an opportunity to discuss written description and enablement issues, it upheld a district court’s finding that a written description of a particular embodiment was sufficient to support broad patent claims to a pharmaceutical composition. Amgen v. Hoechst Marion Roussel, Inc., Case No. 01-1191 (Fed. Cir. Jan. 6, 2003).

The Amgen patent related to the production of erythropietin, an endogenous hormone that regulates red blood cell formation. In part, Hoechst argued the patent specification failed to satisfy the written description requirement in support of a claim to a "pharmaceutical composition…of erythropietin…purified from mammalian cells grown in culture" because the patent failed to sufficiently describe "all vertebrate and mammalian cells as engineered in the claimed invention." The Federal Circuit upheld the district court’s finding of validity stating "…the descriptions adequately described to those of ordinary skill in the art in 1984 [the filing date of the application for the patent] the use of the broad class of available mammalian and vertebrate cells to produce the claimed high levels of human erythropoietin in culture."

The Federal Circuit distinguished its Eli Lilly (1997) and Enzo Biochem (2002) discussions regarding the written description of claims encompassing genetic material (DNA). In Eli Lilly, claims to a human cDNA sequence of an insulin gene were held invalid where only the insulin gene of a rat cDNA sequence was disclosed. In Enzo Biochem, the Court clarified that the written description requirement may be satisfied where one of skill in the art would have knowledge that a functional description of genetic material is correlated to a particular, known structure. Here, the Court found the claim terms at issue are not directed to "new or unknown biologic materials that ordinarily skilled artisans would easily miscomprehend." Rather, the claims simply recite "types of cells that can be used to produce recombinant human EPO." Therefore, according to the majority of the panel, while Hoechst might have been justified in challenging the adequacy of disclosure of the vertebrate or mammalian host cell, the Court found it was not warranted in challenging the adequacy of the disclosure of the DNA itself.

Hoechst also challenged the district court finding that a skilled artisan could have used various cultured vertebrate and mammalian cells to produce EPO. Here, the district court credited Amgen’s witnesses stating "any challenge which one of ordinary skill in 1984 may have encountered in attempting to make and use the claimed invention using other than cultured mammalian cells could be resolved by experimentation falling short of undue."

The majority found no "clear error" in this finding as a factual determination and affirmed. However, there was a vigorous dissent on this point. Judge Clevenger, citing Federal Circuit precedent, including Eli Lilly, called into question the written description holding "disclosure of a species may not suffice to describe a genus" and citing In re Vaeck, "claims failing to recite a necessary element of the invention fail for lack of an enabling disclosure," called into question the enablement holding "[a]t the very least, the absence of structural limitations in the patent [claims] raises questions of its enablemen. …"

In the second case, much to the patentee’s chagrin, the Federal Circuit did not apply such deference to the predictability of cell transformations in the plant kingdom. In Plant Genetic Systems, N.V. (now Aventis Crop Science, N.V.) v. DeKalb Genetics Corp., Case No. 02-1011 (Fed. Cir., Jan. 13, 2003), the Federal Circuit affirmed the district court’s holding that the asserted patent claims were invalid for lack of enablement.

Aventis’ claims were drawn to genetically engineered, herbicide-resistant plant cells, which Aventis contended applied broadly to dicot and monocot plants. The Federal Circuit concluded that the full scope of the invention as claimed by Aventis was not enabled. While the specification disclosed transformation of dicots, the Court found that DeKalb proved by clear and convincing evidence that "practicing stable gene transformation for monocot cells [at the time of patent filing] in 1987 required undue experimentation." Based on In re Hogan (1977) (enablement is determined as of the effective filing date of the patent) the Court held that if "an inventor [claims] what was specifically desired but difficult to obtain at the time the application was filed," the claims are enabled only "[if] the patent discloses how to make and use it." While transformed monocots were desired, as of the filing date "stable transformed monocot cells were difficult to produce and the … patent gave no instruction how." Further, the Court found that the district court properly used a post-filing date report, indicating the first transformation of corn cells, to support its holding.

The Court also rejected Aventis’ argument that the district court erred in not making any finding regarding the pioneering nature of the invention. The Court explained that "pioneer inventions" are not deserving of a lower standard of enablement and that any statement in Hogan to the contrary was dicta.