In Millenium v. Sandoz, the claim at issue recites a lyophilized compound that is an ester of bortezomib and D-mannitol. The Federal Circuit formulated the obviousness analysis by asking whether a person of ordinary skill, seeking to remedy the known instability of bortezomib "would obviously produce the D-mannitol ester of bortezomib, a previously unknown compound." Employing a lead compound analysis, the court concluded that the answer was no. Using bortezomib as the lead compound, the court found that no cited reference provided a reason to produce the claimed mannitol ester. The court also rejected the district court's inherency analysis as impermissible hinsight.