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Federal Circuit Balances Nuances of Claim Construction with Requirements of 35 U.S.C. § 112

January 06, 2003

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Last Month at the Federal Circuit - February 2003

Michel (author), Schall, and Clevenger (dissenting)

In Amgen, Inc. v. Hoechst Marion Roussel, Inc., No. 01-1191 (Fed. Cir. Jan. 6, 2003), the Federal Circuit affirmed-in-part and vacated-in-part the district court’s rulings and remanded for further proceedings.

Amgen, Inc.’s (“Amgen”) five patents-in-suit relate to a non-naturally occurring protein, erythropoietin (“EPO”), for treating patients who lack normal levels of naturally occurring EPO. Amgen pioneered a commercial process for producing EPO by transfecting exogenous (i.e., foreign) DNA into Chinese hamster ovary cells. As a result, the cells expressed human recombinant EPO in significant amounts.

Hoechst Marion Roussel, Inc. and Transkaryotic Therapies, Inc. (collectively “TKT”) later developed another method to produce EPO by using an endogenous (i.e., naturally occurring) EPO gene in human cells. TKT transfected a viral promoter and other DNA to alter the endogenous EPO gene, thereby causing the human cells to produce EPO in greater abundance.

Amgen’s asserted claims are not limited to the use of exogenous DNA or nonhuman cells. However, TKT alleged that Amgen’s specification limited the invention, hence the claims, to the use of exogenous DNA, pointing, e.g., to a description of EPO as being “uniquely characterized . . . [as] the product of prokaryotic or eukaryotic host expression . . . of exogenous DNA sequences.” The Federal Circuit disagreed that the claims should be so limited. Relying in part on the doctrine of claim differentiation, the Court found that a nonasserted claim reciting “exogenous DNA” provided a rebuttable presumption that the asserted claims have a different scope. Additionally, the Court did not apply much weight to the Examiner’s remarks commenting that the application taught only cells transformed with exogenous DNA, because the Examiner eventually allowed broader claims.

The Federal Circuit also upheld the district court’s construction that “non-naturally occurring,” “vertebrate cells,” and “mammalian cells” should be given their ordinary and customary meaning to encompass the use of human cells. Amgen’s specification disclosed the use of human cells in culture and the Court found no record of Amgen’s clear disavowal of human cells.

The Federal Circuit affirmed the district court’s holding that Amgen’s failure to describe the use of endogenous DNA in its specification did not invalidate the claims for lack of written description. The Federal Circuit agreed with the district court that the claims at issue were directed to compositions, and thus the written description inquiry need not address how the product was made or any future developments of the process for making EPO.

The Court also found that Amgen’s specification sufficiently described all vertebrate and mammalian cells and did not expressly exclude the use of exogenous human EPO DNA in human cells or endogenous DNA. Even though the specification described only two species of vertebrate or mammalian cells, neither of which were human cells, the Court found that one of ordinary skill in the art could recognize the identity of the members of the genus, including human cells. Moreover, the Court found that vertebrate or mammalian cells did not relate to new or unknown biological species that could be miscomprehended by one of ordinary skill in the art, unlike the technology in Regents of the University of California v. Eli Lilly & Co., 119 F.3d 1559 (Fed. Cir. 1997). There, the claims required a precise definition of the DNA sequence itself. The Court found this distinct from Amgen’s claims, which related to the EPO-producing cell and not to the DNA itself.

TKT cited Gentry Gallery, Inc. v. Berkline Corp., 134 F.3d 1473 (Fed. Cir. 1998), to support its position that Amgen’s failure to explicitly claim the use of exogenous DNA omitted an “essential” feature of the invention. The Gentry court had invalidated the claims for lack of written description because the patent did not adequately describe a sectional sofa having reclining controls in a location other than on the console. The Court found that Amgen’s allegedly limiting statements in the specification did not rise to the level of the Gentry specification, which expressly limited the location of the controls to the only possible location. In contrast, Amgen’s invention was not about sequence location, but rather, it was about the production of human EPO using those sequences, according to the Court.

The Federal Circuit found certain composition claims enabled even though the claims covered compositions derived from TKT’s endogenous DNA method developed after Amgen’s application was filed. Again, the Court determined that the method for making the composition was immaterial to the enablement inquiry for a composition claim, and, thus, Amgen did not need to describe laterdeveloped methods for preparing the compositions. Because the specification needs only to teach one mode of making and using a claimed composition—a requirement Amgen satisfied—the Court stated that Amgen’s failure to describe endogenous activation was legally irrelevant.

Amgen was also entitled to claims covering all “vertebrate cells” able to produce certain levels of human EPO, even though Amgen only described one technique for making the claimed EPOproducing cell. Although disclosing only one or two species may not enable a broad genus, the Court found that Amgen easily bridged any gaps between the disclosure and the claim scope, because expert testimony and postfiling publications established that the skilled artisan could have readily used various vertebrate and mammalian cells to produce human EPO and could have determined whether certain promoter and vertebrate cells would work.

With regard to validity based on prior art, the Court concluded that prior art patents are presumed enabled for both claimed and unclaimed subject matter. The Court noted that the PTO can presume a cited prior art patent is operable, thus shifting the burden to the applicant to rebut this presumption. Similarly, the Court reasoned, district courts should be entitled to presume enablement for the entire patent disclosure. A patentee can overcome this presumption by providing persuasive evidence of nonenablement. The Federal Circuit then found that the district court had improperly placed the burden of rebuttal on TKT, although this was harmless error. The Court, nonetheless, remanded the novelty issue to the district court in light of a new claim construction.

Amgen’s failure to identify a standard test for determining whether “glycosylation . . . differs from that of human urinary erythropoietin” rendered those claims invalid for indefiniteness under § 112, second paragraph. The specification describes three different methods for measuring glycosylation, but the district court found the claims not limited to those methods. Amgen contended that one of ordinary skill in the art could identify a standard test based on its specification. Evidence, however, showed that the urinary EPO itself, which was the standard for comparison, produced variable glycosylation patterns. For example, experiments showed different glycosylations for two urinary EPO
samples prepared from the same batch of starting materials. In light of the variability of the standard and Amgen’s failure to teach a standard test for glycosylation, the Court found the claim indefinite as no narrowing construction could be properly adopted.