An analysis of the binding efficiencies of drugs and their leads in successful drug discovery programs.

In order to investigate the evolution of binding efficiency in successful drug discovery programs, a data set of 60 lead/drug pairs with known binding affinities has been compiled and analyzed. Low-end thresholds for the binding efficiencies of viable leads and drugs have been derived. On average, the drugs in the set are significantly larger and more potent but have similar lipophilicity relative to their originating leads, suggesting that the ability to maintain low levels of lipophilicity while increasing molecular weight is one of the keys to a successful drug discovery program. A number of examples demonstrate that large increases in binding efficiency from leads to more elaborate drugs sharing the same scaffold can be achieved. The importance of dissecting a lead structure to identify the most efficient fragments and the option of sacrificing binding efficiency to optimize other properties are discussed, and relevant examples are highlighted.