By Kevin Noonan.

The peripatetic case of Amgen v. HMR has once again been reviewed by the Federal Circuit.  No. 05-1157, decided August 3, 2006.  Once again the Court has failed to lay the several issues in the case to rest.  While affirming infringement and validity of two of the patents in suit, the court has remanded the matter once again to the district court in view of its de novo claim construction, and perhaps predictably disagreed with the lower court and reversed a determination of infringement under the Doctrine of Equivalents.

The case has two interesting aspects.  First, citing the rubrics of Phillips the court came to its own determination of the meaning of the term “therapeutically effective amount” with regard to a claim for recombinant erythropoietin (EPO).  EPO is a naturally-occurring hormone that stimulates the body to produce red blood cells, and its absence (or insufficiency) causes anemia.  The standard clinical measure of anemia is the hematocrit, or the percent of whole blood comprised of red blood cells. In construing the term “therapeutically-effective amount,” the district court had required that EPO falling within the scope of the claim containing the term increase hematocrit and have any other biological properties of naturally-occurring EPO. 

The Federal Circuit disagreed, and in doing so provided a nice illustration that Phillips has not changed the Court’s capacity for arriving at its own idiosyncratic construction.  The Court determined that the lower court had improperly focused on hematocrit, which is one of EPO’s biological properties recited in the specification, to the exclusion of several others, including increasing stimulation of reticulocyte response, development of ferrokinetic effects, erythrocyte mass changes, and stimulation of hemoglobin.  The Court noted in particular that the specification recited that the therapeutic properties of recombinant EPO “included” all of these, and that the specification further stated that recombinant EPO was therapeutically useful even if it lacked some but not all of these properties. 

Of course, the Court seems to have not considered the fact that all of the recited properties are related to the clinical measurement of hematocrit, since they are all part of the biological developmental pathway leading to an increase in the number of red blood cells in blood.  Thus, by cherry-picking the language of the specification, the Court was able to arrive at a facially-reasonable claim construction that seems to run contra to clinical reality.  This portion of the matter has been remanded, for further consideration in view of the Court’s claim construction, on the issue of invalidity over prior art references to EPO preparations that did not increase hematocrit but may have had one of the other recited biological properties.

The second issue is the doctrine of equivalents.  The “predicted” recombinant EPO protein contains 166 amino acids, but as produced naturally (and using HMR’s recombinant process) EPO has only 165 amino acids.  The issue before the Court was whether Amgen was entitled to assert claims to HMR’s recombinant EPO as an equivalent.  The district court twice found in the affirmative, and the Federal Circuit remanded in its first review so the lower court could consider the issue in view of Festo. Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722, 740–41 (2002).  The district court having arrived at the same conclusion, infringement under the doctrine of equivalents, the Federal Circuit reversed, finding estoppel arising during prosecution.  Specifically, the Court held that  preliminary amendments resulting in claim language reciting the 166 amino acid species were not made for reasons tangentially related to the asserted equivalent, as found below, but raised prosecution history estoppel that precluded asserting the claim against HMR’s 165-amino acid species.  The Court’s holding was based in part on Amgen’s cancellation of claim limitations related to “fragments” of the 166-amino acid species, and in part because it found erroneous the district court’s determination that the amendments were made to limit the species to human EPO (the Court noted that if Amgen had intended to so limit the claims the mere addition of the word “human” would have been sufficient).  Finally, the Court rejected the notion that amendments made to avoid a double-patenting rejection were “tangential to patentability.”

For those keeping score, the Court in its two decisions has affirmed the district court’s judgment that two of Amgen’s patents are not invalid and are infringed, also affirmed that another Amgen patent is invalid, reversed a finding of infringement under the doctrine of equivalents (but affirmed that this patent is also not invalid), and for one patent remanded the issue of invalidity to the district court while affirming that if valid this patent is also infringed.  As noted in Judge Michel’s dissent (over the claim construction issue), the district court is now in position to decide whether to grant an injunction, keeping HMR’s competing EPO product off the market until at least the expiration of two of Amgen’s patents.  For the parties, that may be (or have to be) enough.