Canertinib as an FLT3 Inhibitor with Potent Activity Against FLT3-Mutated and AC220-Resistant Acute Myeloid Leukemia

FMS-like tyrosine kinase 3 (FLT3) mutations are among the most common genetic lesions in acute myeloid leukemia (AML) and are frequently associated with high relapse rates and poor prognosis. Although current FLT3 inhibitors have improved outcomes, acquired resistance limits their long-term efficacy. Accordingly, developing new FLT3 inhibitors is important. We screened a natural-compound library to identify small molecules targeting the FLT3 protein. Kinase activity assays and cellular thermal shift assays (CETSA) collectively demonstrated the binding of canertinib to FLT3. Canertinib was tested in FLT3-mutated cells (32D, 32D-ITD, 32D-ITD+TKD, MV4-11 and blasts), and FLT3 wild-type cells. Cell viability was measured using the Cell Counting Kit-8 (CCK-8) assay; apoptosis was assessed by Annexin V staining; and phosphorylation of FLT3 and downstream pathways was analyzed by western blotting. A secondary-resistance model (MV4-11-ACR) was generated by treating MV4-11 cells with AC220. The effects of canertinib on cell viability, apoptosis, and FLT3 phosphorylation inhibition were evaluated in MV4-11-ACR cells. Canertinib directly targets the FLT3 protein. In FLT3-mutated expressed cells, canertinib effectively inhibited proliferation, induced apoptosis, and markedly reduced phosphorylation of FLT3 and its downstream effectors AKT, extracellular signal-regulated kinase (ERK), and STAT5, indicating precise on-pathway blockade of FLT3 signaling. Canertinib exerted similar effects on MV4-11-ACR cells as on the parental cells. Canertinib is an FLT3 inhibitor that directly targets the FLT3 protein to overcome FLT3 mutations and AC220 resistance in acute myeloid leukemia. These findings support canertinib as a promising candidate to overcome acquired resistance to FLT3 inhibitors.