Earlier, the Court of Appeals for the Federal Circuit affirmed a District Court’s decision that Transkaryotic Therapies Inc. (TKT) and Aventis Pharmaceuticals Inc. infringe Amgen’s erythropoietin (EPO) patent estate. Amgen Inc., v. Hoechst Marion Roussel, Inc. (Now Aventis) and Transkaryotic Therapies, Inc., (05-1157). The court’s decision upheld the validity of two of Amgen’s EPO patents and the infringement by TKT of three patents and 12 claims, including a patent that does not expire until 2015.

Now, Amgen’s petition for a panel rehearing and rehearing en banc has been denied by the Court of Appeals for the Federal Circuit.

The issue remains over the District Court’s findings on the infringement and validity of two patents with claims to the production of erythropoietin, the infringement of one product patent under the doctrine of equivalents, and the validity of one product patent. The Federal Circuit found the production patents valid and infringed (U.S. Patent Nos. 5,618,698 and 5,756,349). The court reversed the District Court’s determination that TKT infringed Amgen’s U.S. Patent No. 5,621,080 under the doctrine of equivalents, and remanded to the District Court for further consideration of the remaining validity issue on one of the other product patents (U.S. Patent No. 5,955,422).

The patents at issue are directed to recombinant DNA technology relating to the production of the hormone erythropoietin (“EPO”). Epogen a form of the protein erythropoietin that is produced outside of the human body and delivered by injection. Transkaryotic’s product Dynepo, however, is a gene. When injected, Dynepo leads to the production of a slightly different form of erythropoietin inside the body.

Transkaryotic uses what it calls gene-activation technology. It relies on the fact that all human cells have a complete set of genes, even though the gene for producing EPO is not active except in kidney cells. So Transkaryotic inserts an on switch into human cells grown in culture, activating the gene for EPO. The switch is surrounded by genetic sequences that match those found upstream of the EPO gene on the chromosome. That guides the switch to the spot where it will turn on the EPO gene and not any other gene.

On remand, the trial court construed “therapeutically effective amount” in claim 1 of the ‘422 patent to require that the claimed EPO increase hematocrit and also be useful in healing or curing certain patients identified in the specification (those with anemia-like disorders). The CAFC held that the language used in the specification indicated that the invention was used in therapy to produce any or all of five identified effects; increasing hematocrit was only one of the biological effects produced by the invention. Thus, the trial court misinterpreted this part of the specification when it read the passage as limiting the invention to products with any or all of the first four effects ascribed in vivo to EPO and also an increase in hematocrit.

The CAFC felt that the trial court made an artificial distinction between the first four effects and the fifth effect (an increase in hematocrit). Also the CAFC believed that “therapeutic utility” was not dependent on the product having an effect in a living being, such as curing disease believing that the patentee used the words “therapeutically effective” in order to broadly claim a pharmaceutical composition with a wide range of effects.

The trial court ruled that claims 2-4 of the ‘080 patent were not invalid and that Amgen was not estopped from asserting infringement under the doctrine of equivalents. The trial court found that the presumption was rebutted because the amendment limiting the claims of the ‘080 patent to EPO with the amino acid sequence of Figure 6 was tangential to EPO having a 165-amino acid sequence and also set forth an alternative rationale based on the “some other reason” language.

The Federal Circuit upheld the trial court’s finding that Amgen failed to show that EPO with a 165-amino acid sequence was not foreseeable at the time of the amendment. However, the CAFC held that the trial court erred when it found that Amgen had met its burden of rebutting the presumption under both the tangentiality and “some other reason” rationales. Amgen’s third preliminary amendment limited the ‘080 patent to EPO having 166 amino acids. As for the “some other reason” rationale, the patentee knew of the 165-amino acid sequence at the time of the amendment, but chose to limit the claims to the 166-amino acid sequence.

Amgen argued that the district court correctly interpreted the term since only amounts of EPO producing effects—particularly increased hematocrit—that counteract these anemia-like diseases are “therapeutically effective.”

Chief Judge Michel, dissenting-in-part, summed up things thusly:

[S]ince the majority holds that other asserted patents are not invalid and are literally infringed by HMR 4396, (and here I agree), the district court likely will enter an injunction … Prolonging this litigation seems futile when, in the end, an injunction will likely issue regardless of how “therapeutically effective” is construed or whether claim 1 of the ‘422 patent is invalid.

In the petition for rehearing, Judge Michel and Judge Rader dissented stating:

In my view, four practical problems have emerged under the Markman-Cybor regime: (1) a steadily high reversal rate; (2) a lack of predictability about appellate outcomes, which may confound trial judges and discourage settlements; (3) loss of the comparative advantage often enjoyed by the district judges who heard or read all of the evidence and may have spent more time on the claim constructions than we ever could on appeal; and (4) inundation of our court with the minutia of construing numerous disputed claim terms (in multiple claims and patents) in nearly every patent case.

Our standard of review of no deference to the trial judge’s claim constructions, expressed in Cybor, rests upon the premise that claim construction is always a purely legal exercise, devoid of factual content. We have likened claim construction to statutory construction. I believe that this analogy is open to serious question. In interpreting statutes, a judge, whether trial or appellate, essentially asks himself/herself, “What does the disputed term mean to me, the judge, as an artisan in the law?” With claim construction, on the other hand, the judge is supposed to inquire, essentially, “How would the average artisan in the relevant field of technology understand the disputed claim terms in the context of the rest of the patent, the prosecution history, and the prior art?”

This petition order also had a dissents from Judges Newman and Moore with concurrences by Judges Lourie, Gajarsa, Linn and Dyk. With such a divided court, we may well see Amgen VI in the Supreme Court. All over a product that Transkaryotic dropped years ago.

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