In the hit-to-lead stage, the „hit” compound, which still possess some liabilities, is optimized in order to achieve the lead molecule. This new entity has all required biological properties but it I still not a clinical candidate and also require further optimization.
During “hit-to-lead” stage both computational methods (in silico) and general knowledge from medicinal chemistry allow us to optimize several aspects in one go: selectivity, solubility, stability and activity towards particular molecular targets. In the next stage “lead optimization” final modification are made to “tune” the compound to have even better pharmacological properties. The outcome of the project is the molecule which has all required properties and can enter the clinical phase.