Abstract 27: Identification and characterization of a novel dual FLT3/microtubule polymerization inhibitor through cell-based screening

Activating mutations in FLT3 receptor tyrosine kinase are found in one-third of acute myeloid leukemia (AML) patients and are associated with disease relapse and bad prognosis. Majority of these mutations are Internal tandem duplications (ITD) in the juxtamembrane domain of FLT3 and have been validated as a therapeutic target. Clinical success of selective inhibitors targeting oncogenic FLT3, however, has been limited due to the acquisition of drug resistance. Here we report the identification of a dual FLT3/microtubule polymerization inhibitor, HH-IA-208, through cell-based screenings for the differential killing of leukemia cell lines expressing FLT3-ITD (MV411) or BCR-ABL (K562) using an MTS proliferation assay and for mitotic inducers using a dot-blot assay for histone H3 phosphorylation in HCT116 cell line. HH-IA-208, a chalcone derivative, inhibits FLT3 in vitro and treatment of FLT3-ITD+ cell lines with HH-IA-208 results in reduced FLT3 signaling. Similarly, HH-IA-208 inhibits tubulin polymerization in a biochemical assay and in cells that results in a mitotic arrest. HH-IA-208 is selectively more potent in leukemia cell lines expressing FLT3-ITD and treatment for 24 and 48 hours with the inhibitor results in apoptotic cell death. Furthermore, HH-IA-208 is able to overcome TKD mutation-mediated acquired resistance to FLT3 inhibitors in a MOLM13 cell line expressing FLT3-ITD with the D835Y mutation. HH-IA-208, therefore, is a promising lead for the discovery of dual target FLT3 inhibitors that can overcome resistance to selective FLT3 inhibitors. Citation Format: Haleema Sadia Malik, Aishah Bilal, Rahim Ullah, Maheen Iqbal, Rahman Shah Saleem, Hidayat Hussain, Amir Faisal. Identification and characterization of a novel dual FLT3/microtubule polymerization inhibitor through cell-based screening [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 27.