Profiling and Optimizing Targeted Covalent Inhibitors through EGFR-Guided Studies.

Targeted covalent inhibitors (TCIs) are actively pursued in drug discovery due to their prolonged target engagement and clinical efficacy. Although kinetic parameters provide a path to their optimization, systematic design strategies and practical guidance remain underexplored. In this study, the EGFR kinase is deployed as a model system to elucidate structural and functional determinants critical for directing the optimization of irreversible TCIs. Functional analyses reveal a two-phase optimization process, underscoring the importance of balancing─rather than maximizing─the inactivation efficiency rate (kinact/KI). Selective inhibition of the oncogenic L858R/T790M mutant over the wild-type is achieved by tuning this balance, particularly for TCIs exhibiting the fastest kinact/KI. Structural studies indicate that certain hydrophobic and hydrophilic interactions are associated with L858R/T790M selectivity, offering insights into structure-guided design. These results offer a broadly applicable approach for prioritizing compounds and support the integration of kinetic and selectivity data in TCI discovery campaigns.