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Limited Disclosure in Patent Specification Limits Scope of Claims

January 31, 2003
Holtman Ph.D., M. Andrew

Decision icon Decision

Last Month at the Federal Circuit - February 2003

Judges: Newman (author), Friedman, and Rader (concurring)

In Biogen, Inc. v. Berlex Laboratories, Inc., No. 01- 1058 (Fed. Cir. Jan. 31, 2003), the Federal Circuit affirmed the district court’s claim construction for Berlex Laboratories, Inc.’s (“Berlex”) U.S. Patent Nos. 5,376,567 (“the ‘567 patent”) and 5,795,779 (“the ‘779 patent”), affirmed the SJ of no literal infringement of the ‘567 patent and noninfringement of the ‘779 patent, and vacated the SJ of no infringement under the DOE for the ‘567 patent.

The ‘567 patent and ‘779 patent, a continuation of the ‘567 patent, relate to the production of human interferon in Chinese hamster ovary (“CHO”) cells. At issue was whether Berlex’s patents claim both “linked” and “unlinked” cotransformation of CHO cells. Linked cotransformation describes a process of inserting foreign DNA into a cell using a single vector containing all the desired genes, such as the human-interferon gene and a marker gene. Unlinked cotransformation, on the other hand, describes a transformation technique where the desired genes reside on separate vectors. Biogen, Inc. (“Biogen”) uses an unlinked cotransformation approach to insert the human-interferon gene and a marker gene into CHO cells.

The district court had determined that the ‘567 patent specification discusses a single construct method for inserting foreign DNA into CHO cells, that this procedure limits the scope of all claims, and that the prosecution history and testimony by expert witnesses supported this narrower scope of the ‘567 patent claims. On appeal, Berlex pointed to language in the specification and prosecution history that indicates that the ‘567 patent claims cover both (1) the use of CHO cells to produce high levels of human interferon generally, and (2) the use of a single construct carrying the human-interferon gene and a selectable marker. Berlex argued that linked cotransformation is only a preferred embodiment and, thus, not limiting on the scope of the broader claims. Finally, Berlex noted that the ‘567 patent application was filed after claims specific to a single DNA construct had been allowed in the parent application, U.S. Patent No. 4,966,843 (“the ‘843 patent”), and that the ‘567 patent claims were intended to be of different scope.

Biogen responded that Berlex’s asserted breadth of the ‘567 patent claims is not supported by the specification and would render the ‘567 patent invalid for lack of an adequate written description. Biogen further responded that, but for a few general statements, the entire specification of the ‘567 patent is directed solely to the invention, whereby a single construct comprising the human-interferon gene and a marker gene is used to insert the DNA into CHO cells.

The Federal Circuit agreed with Biogen and affirmed the district court’s ruling that the ‘567 patent specification defines the invention as the use of a single DNA construct to introduce the linked human-interferon gene and selectable-marker gene into CHO cells. The Federal Circuit found that the prosecution record shows that the Examiner also viewed the invention of the ‘567 patent application as the use of a single DNA construct. In doing so, the Federal Circuit noted the Examiner’s comments made during an obviousness-type double patenting rejection and in his Reasons for Allowance both indicate to the interested public that the PTO viewed the use of a single DNA construct with linked genes as the only supportable scope of the claims.

The Federal Circuit further addressed Berlex’s statement that the district court had improperly relied on arguments made in the prosecution of the parent ‘843 patent to limit the ‘567 patent claims. The Court agreed that while such statements should not automatically apply to limit different claims in a separate application, they can do so in some circumstances. The Court commented that the statement by the applicant during the ‘567 patent prosecution that the ‘567 patent claims “fall within the scope of subject matter already allowable over the prior art” weighs heavily against the applicant’s proposed broader construction in the later application. Additionally, the Court noted that the applicant’s comments during prosecution cannot enlarge the content of the ‘567 patent specification.

With respect to infringement of the ‘567 patent, the Federal Circuit affirmed the SJ of no literal infringement, but reversed the SJ of noninfringement under the DOE, based on prosecutionhistory estoppel. The Federal Circuit noted that in prosecuting a related application, the applicant is not barred from raising new arguments or correcting past errors. Thus, the district court had erred when it summarily concluded that Berlex was estopped from asserting that multiple DNA constructs for unlinked cotransformation infringe by equivalence based on the fact that the applicant has disclaimed such use in the parent ‘843 patent. The Federal Circuit remanded this portion of the case to determine the facts of infringement by equivalency.

The district court next addressed Berlex’s ‘779 patent, which claims a CHO cell-culture composition wherein the human interferon is secreted at a concentration range of 150,000-600,000 IU/ml of medium. The district court determined that the claimed concentration of 150,000-600,000 IU/ml must represent interferon concentrations obtained at the end of the production process. In so holding, it found that even though Biogen’s CHO culture composition secreted interferon within that range, it did so only as the cell composition continued to a final interferon concentration of 1,200,000 IU/ml. In other words, the district court held that traversing the range set forth in the ‘779 patent claims was not sufficient for infringement when the final concentration fell outside of that range.

The Federal Circuit agreed but also noted that during the prosecution of the ‘779 patent, the applicant told the Examiner that the activity limits of 150,000-600,000 IU/ml were included in the claims only to expedite prosecution. The Court concluded that claims deliberately limited to expedite prosecution could not later regain a broader scope for infringement purposes.