Mylan Pharms. Inc. v. Merck Sharp & Dohme Corp. United States Court of Appeals of the Federal Circuit, 2022 50 F.4th 147

The claims at issue in this case are directed to sitagliptin dihydrogenphosphate (``sitagliptin DHP''), a dipeptidyl peptidase-IV (``DP-IV'') inhibitor and the active ingredient in JANUVIA, which is marketed by Merck for the treatment of non-insulindependent (i.e., Type 2) diabetes. Mylan petitioned for inter partes review (IPR) of the claims, arguing that the challenged claims were anticipated and/or rendered obvious by the disclosure of a genus of 957 salts in an earlier Merck-owned U.S. patent and its equivalent International Patent Publication (referred to collectively as ``Edmondson''). In particular, Mylan argued that under In re Petering (a 1962 decision of the Court of Customs and Patent Appeals) the disclosure of the genus anticipated the claims because a skilled artisan reading Edmondson would ``at once envisage'' the claimed sitagliptin DHP salt. But the Board rejected this argument, finding that none of the challenged claims were anticipated by Edmondson. The Federal Circuit affirmed, finding that while In re Petering does stand for the proposition that a skilled artisan may ``at once envisage each member of [a] limited class,'' the ``key term'' in this statement is the word ``limited.'' The court found that the genus of 957 salts disclosed in Edmondson is a far cry from the 20 compounds ``envisaged'' by the narrow genus disclosed in Petering.