The lead compound analysis, or LCA, originally a creature of abbreviated new drug application litigation, has more recently found its way into chemical obviousness arguments at the U.S. Patent and Trademark Office.
Although less inclined than the courts to disqualify prior art under an LCA, the Patent Trial and Appeal Board has nudged the USPTO closer to the courts for claims relating to new molecules. In appropriate cases, patent applicants in ex parte appeals have begun to win reversals with lead compound arguments.
As applied in the courts, an LCA diverges from a traditional chemical obviousness analysis at the USPTO. The first step of an LCA begins by identifying a lead compound, i.e., the most promising, but not necessarily the closest, prior art starting point.
Conversely, the USPTO has traditionally focused its obviousness analysis on the most structurally similar prior art molecules. And with limited exceptions, the traditional approach has recognized any prior art molecule with a useful property as a valid starting point.
The more stringent criteria applied to lead compound selection can raise the bar for establishing obviousness, by shifting the analysis away from the closest prior art. In some cases, the USPTO has reconciled the two approaches by simply designating as lead compounds the closest prior art molecules possessing some useful property.
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