Analyzing Biologics Under the Doctrine of Equivalents and Prosecution History Estoppel

In a recent decision, Ajinomoto v. ITC, the Federal Circuit addressed the issues of doctrine of equivalents and prosecution history estoppel as applied to patent claims reciting specific amino acid sequence of a biologic. On appeal, the Federal Circuit affirmed the decision by the United States International Trade Commission that a protein having 85% to 95% identity infringed a claim reciting specific amino acid sequences under the doctrine of equivalents.