Discovery of LWY713 as a potent and selective FLT3 PROTAC degrader with in vivo activity against acute myeloid leukemia

Fms-like tyrosine kinase 3 (FLT3) has been validated as a therapeutic target for acute myeloid leukemia (AML). While a number of FLT3 kinase inhibitors have been approved for AML treatment, the clinical data revealed that they cannot achieve complete and sustained suppression of FLT3 signaling at the tolerated dose. Here we report a series of new, potent and selective FLT3 proteolysis targeting chimera degraders. The optimal compound LWY713 potently induced the degradation of FLT3 with a DC50 value of 0.64 nM and a Dmax value of 94.8% in AML MV4-11 cells with FLT3-internal tandem duplication (ITD) mutation. Mechanistic studies demonstrated that LWY713 selectively induced FLT3 degradation in a cereblon-and proteasome-dependent manner. LWY713 potently inhibited FLT3 signaling, suppressed cell proliferation, and induced cell G0/G1-phase arrest and apoptosis in MV4-11 cells. Importantly, LWY713 displayed potent in vivo antitumor activity in MV4-11 xenograft models.