LCK-targeting molecular glues overcome resistance to inhibitor-based therapy in T-cell acute lymphoblastic leukemia.

Drug resistance is a major challenge in cancer therapy, especially in hematologic malignancies in which kinase inhibitors have transformed treatment yet are frequently undermined by drug resistance. Although targeted protein degradation (TPD) offers a mechanistically distinct mode of action compared with inhibition-based therapeutic therapies, the potential value of TPD in drug-resistant blood cancer remains unclear. Here, we report the discovery of cereblon (CRBN)-recruiting molecular glue degraders (MGDs) targeting lymphocyte-specific tyrosine kinase (LCK), an oncogenic kinase in T-cell acute lymphoblastic leukemia (T-ALL). By high-throughput screening and medicinal chemistry optimization, we developed a series of MGDs that induced CRBN-dependent degradation of LCK as well as potent cytotoxicity in T-ALL in vitro. Structure-activity relationship analysis and ternary complex modeling revealed a noncanonical degron at the LCK-CRBN interface involving the G-loop, whose mutation disrupts this interaction. Unlike inhibitors and inhibitor-based proteolysis-targeting chimeras, these MGDs engage LCK in regions distal to the ATP-binding site, and thus their activities in T-ALL are not affected by gatekeeper LCK mutations that drive resistance to inhibitor-based therapeutics. Taken together, our data highlight the potential of LCK-targeting MGDs as a strategy to overcome kinase inhibitor resistance in T-ALL, offering a framework for targeting kinase dependencies in drug-refractory hematologic malignancies more broadly.