Discovery of picomolar ABL kinase inhibitors equipotent for wild type and T315I mutant via structure-based de novo design.

Although the constitutively activated break-point cluster region-Abelson (ABL) tyrosine kinase is known to cause chronic myelogenous leukemia (CML), the prevalence of drug-resistant ABL mutants has made it difficult to develop effective anti-CML drugs. With the aim to identify new lead compounds for anti-CML drugs, we carried out a structure-based de novo design using the scoring function improved by implementing an accurate solvation free energy term. This approach led to the identification of ABL inhibitors equipotent for the wild type and the most drug-resistant T315I mutant of ABL at the picomolar level. Decomposition analysis of the binding free energy showed that a decrease in the desolvation cost for binding in the ATP-binding site could be as important as the strengthening of enzyme-inhibitor interaction to enhance the potency of an ABL inhibitor with structural modifications. A similar energetic feature was also observed in free energy perturbation (FEP) calculations. Consistent with the previous experimental and computational studies, the hydrogen bond interactions with the backbone groups of Met318 proved to be the most significant binding forces to stabilize the inhibitors in the ATP-binding sites of the wild type and T315I mutant. The results of molecular dynamics simulations indicated that the dynamic stabilities of the hydrogen bonds between the inhibitors and Met318 should also be considered in designing the potent common inhibitors of the wild-type and T315I mutant of ABL.