Posts Tagged: "Spectrum Pharmaceuticals"

The issue on appeal was whether a mixture comprising at least 92% of the (6S) isomer of leucovorin would have been obvious when both the 50/50 mixture of isomers and the pure (6S) isomer were known in the art. Affirming the district court, the Federal Circuit agreed that “one of skill would have been motivated to modify the prior art 50/50 mixture to make the claimed mixture,” especially when it was known that the desired activity lies with the (6S) isomer. The Court found no evidence indicating that the claimed mixture “possess[ed] unexpected advantages over the prior art pure material” so as to overcome obviousness.