Extensive exposure to molecularly-targeted therapy elicits mechanisms of drug resistance, typically promoting mutations in the protein target that lower the affinity for the drug inhibitor. Thus, protein kinases, the central targets for drugbased cancer treatment, avoid functional impairment by developing adaptive mutations. Redesigning a drug to target a drug-resistant mutant kinase constitutes a therapeutic challenge. Fernández et al. approach this problem by redesigning the anticancer drug imatinib guided by local changes in interfacial de-wetting propensities of the C-Kit kinase target introduced by an imatinib-resistant mutation. The ligand is redesigned by sculpting the shifting hydration patterns of the target, quantified by the bar plot in the figure. The association with the modified ligand overcomes the mutation-driven destabilization of the induced fit, as shown in the bottom molecular displays. Consequently, the redesigned drug inhibits both mutant and wild-type kinase. The modeling effort is validated through molecular dynamics, test tube kinetic assays of downstream phosphorylation activity, high-throughput bacteriophage-display kinase screening,cellular proliferation assays, and cellular immunoblots. The inhibitor redesign reported delineates a molecular engineering paradigm to impair routes for drug resistance. Inspired by these findings, Fernández et al. envision a strategy for drug redesign that “corners” mutation-induced adaptation, so that the only recourse to avoid drug-promoted inhibition becomes a mutation that renders the target protein functionally inactive. For details, see the article by Fernández et al.on page 4028 in this issue.

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