As we previously reported, earlier this year the Federal Circuit affirmed a district court’s finding that Sandoz’s ZARXIO filgrastim biosimilar and proposed pegfilgrastim biosimilar do not infringe Amgen’s patents. The patents-at-issue were Amgen’s U.S. Patent Nos. 8,940,878 (“the ’878 patent”) and 6,162,427 (“the ’427 patent”). The ’872 patent is directed towards methods of purifying proteins expressed in non-mammalian systems in both non-native soluble and non-native insoluble forms. The ’427 patent is directed towards methods of treatment involving administering a hematopoietic stem cell mobilizing-effective amount of G-CSF before administering chemotherapy to the patient. The District Court for the Northern District California construed the claims of both patents and granted summary judgment of non-infringement of claim 7 of the ’878 patent in favor of Sandoz. Amgen later appealed the decision. The Federal Circuit concluded that there was no infringement and that Amgen could not succeed on its doctrine of equivalents theory, explaining that “[t]he doctrine of equivalents applies only in exceptional cases and is not simply the second prong of every infringement charge, regularly available to extend protection beyond the scope of the claims.” See Amgen Inc. v. Sandoz Inc., 923 F.3d 1023, 1029 (Fed. Cir. 2019).

In June, Amgen filed a petition for rehearing en banc. Amgen argued that the Federal Circuit established a bright line rule that the doctrine of equivalents only applies in exceptional cases and that such a rule is contrary to both Supreme Court precedent and the Federal Circuit’s prior precedent. Amgen argued that the panel decision “represents a profound change in the law that appears to impose an equitable standard explicitly rejected by the Supreme Court.” Pet. at 3. Citing several Supreme Court cases, Amgen argued that the idea that the doctrine of equivalents is available in all cases and is assessed without regard to equities is consistent with over 150 years of Supreme Court precedent. Pet. at 5. Amgen went on to state that under the correct doctrine of equivalents standard for assessing infringement, the Federal Circuit erred in affirming the district court’s decision.

On September 3, 2019, the Federal Circuit partially granted Amgen’s petition. The Federal Circuit ordered that the petition is granted such that the portion of the panel’s opinion stating that the doctrine of equivalents “applies only in exceptional cases” is removed. The Federal Circuit denied the rest of the petition, thereby upholding the panel’s ruling of noninfringement. The Federal Circuit did not provide any reasoning in its order but its decision demonstrates that the prior panel was incorrect in establishing a bright-line rule that the doctrine of equivalents only applies in exceptional cases.