Chemical Space of FLT3 Inhibitors as Potential Anti-AML Drugs.

Background: FLT3 is a member of receptor tyrosine kinase III family, mainly expressed in hematopoietic cells. The aberrant expression and function of FLT3 are strongly related to leukemia, especially acute myeloid leukemia. Its varieties of amino-acid residues mutations, such as FLT3-ITDs and -TKDs, can induce constant proliferation of hematological tumor cells with poor prognosis. Hence FLT3 serves as a promising target in AML chemotherapy.

Objective: This review focused on the progress of FLT3 inhibitors study including those that have entered clinical trials or were reported in numerous patents all over the world. Thus, we provided a useful reference for the development of new anti-leukemia drugs.

Method: Through a comprehensive retrospective study, FLT3 inhibitors in several patent applications were identified and classified into five categories, including quinolone-related, indole-related, ureas, pyrimidines and other compounds.

Results: For each category of compounds, the structural feature, SAR, biological activity and current research status were thoroughly reviewed and analyzed.

Conclusion: Although some of those compounds expressed potent bioactivities and have reached the advanced clinical trials for the treatment of leukemia, there are still several problems need to be faced before they enter the market eventually, especially the drug resistance issue. The improvement of therapeutic potency for FLT3 inhibitors might depend on the useful combination therapy and further refinement of the intrinsic properties of FLT3 inhibitors.