Whether the Federal Circuit erred in holding that a patent claim to an obvious modification of a prior art compound was not invalid as obvious under 35 U.S.C. §103(a) because the prior art compound would not have been selected as a 'lead compound' that was 'most promising to modify in order to improve upon its activity and obtain a compound with better activity?

QUESTION PRESENTED Did the Federal Circuit commit error in holding that a patent claim to an obvious modification of aprior art compound was not invalid as obvious under 35 U.S.C. §103(a) because the prior art compound would not have been selected as a “lead compound” that was “most promising to modify in order to improve upon its activity and obtain a compound with better activity?