Lactate metabolism and epigenetic reprogramming drive c-KIT hyperactivation to mediate Gilteritinib resistance: Rationale for c-KIT degraders over kinase inhibitors

Kinase inhibitors targeting FLT3-ITD, such as Gilteritinib, have emerged as promising targeted therapies. However, recent clinical trials have shown disappointing overall survival (OS) outcomes in acute myeloid leukemia (AML) patients, primarily due to disease recurrence following treatment. We uncovered a potential mechanism underlying Gilteritinib resistance. Gilteritinib treatment induced reprogramming of lactic acid metabolism in AML cells, leading to increased H3K27 lactylation that continuously amplified c-KIT expression and signaling in AML cells. This mechanism enriched leukemia stem cells (LSCs), driving drug resistance and disease relapse. Notably, c-KIT kinase inhibitors failed to effectively counteract the progression of relapsed and refractory AML, as c-KIT overexpression results in amplification of its signaling. To address this issue, a dual degrader targeting both FLT3-ITD and c-KIT was identified. Beyond exhibiting stronger efficacy than Gilteritinib in inhibiting AML cell proliferation, this PROTAC also demonstrates a significant ability to induce cell differentiation. In cell line-derived xenograft (CDX) models, the degrader significantly suppressed FLT3-ITD + AML recurrence and prolonged the survival of experimental mice. Furthermore, in PDX model established using AML cells from Gilteritinib-resistant patients, the degrader showed significantly superior therapeutic efficacy compared to the combination treatment of Gilteritinib and Imatinib. As a candidate drug molecule, this degrader exhibits promising potential for clinical translation.