Interpretating Biotechnology Patent Claims After Phillips

On November 15, 2006, a panel (consisting of Judges Lourie, Rader, and Rader) of the United States Court of Appeals for the Federal Circuit ("CAFC") decided Abraxis Bioscience, Inc. v. Mayne Pharma (USA) Inc. (06-1118), a patent infringement case involving, among other issues, the construction of the term "edetate". In its 2005 decision, the district court below (S.D.N.Y.) found that an anaesthetic pharmaceutical composition for which Mayne Pharma (USA) Inc. ("Mayne") had sought regulatory approval in an Abbreviate New Drug Application, or "ANDA", infringed claims to patents owned by Abraxis Bioscience, Inc. ("Abraxis"), both literally and under the doctrine of equivalents. Mayne appealed the district court's findings of infringement to the CAFC.

Since the CAFC decided Phillips v. AWH Corp., 415 F.3d 1303 (Fed. Cir. 2005) (en banc), there has been much speculation about how claim terms would be interpreted. In Phillips, the CAFC had the opportunity to clarify the principles of claim construction. Many were disappointed when the CAFC opted for flexibility and nuance over bright line rules when interpreting the meanings of claim terms. Whether or not hopes for easy clarity were naive, claim construction post-Phillips continues to rely on the divination of general patterns from CAFC decisions grounded in highly specific patterns of fact.

Even viewed through this prism of caution, Abraxis v. Mayne may may argue for narrower claim interpretations of chemical compounds. The CAFC reversed the district court's broad construction of the meaning of "edetate", along with a finding of literal infringement dependent on this broad construction. Professing to follow the interpretive principles explained in Phillips, the CAFC arrived at a relatively narrow definition of "edetate" as "ethylenediaminetetraacetic acid (EDTA) and derivatives thereof".

The district court had adopted an interpretation of edetate "derivatives" that encompassed not just salts of EDTA (that is, a relatively narrow category of chemical compounds derivable in a relatively direct manner from EDTA), but also structural analogs (that is, an expansive category of structurally similar chemical compounds, some of which are less easily derived from EDTA). By contrast, the CAFC, relying on evidence from the claim language itself and the specification of the patent, rejected the inclusion of structural analogs as impermissibly broad. The fact that the specification mentions only EDTA and specific salts of EDTA, but no structural analogs of EDTA, appears to have been particularly persuasive to the CAFC.

After reversing the district court on literal infringement, the CAFC went on to affirm the finding of infringement under the doctrine of equivalents - a notable outcome itself, given the declining vitality of the latter doctrine in recent years. Thus, the reversal of literal infringement was not decisive in the patent infringement dispute. Nevertheless, Abraxis v. Mayne may still provide valuable insight into the evolution of the CAFC's approach to claim construction, particularly in biotechnology cases.