Related Experiment Video
Updated: Apr 2, 2026
Comet Assay to Quantify DNA Damage in FLT3 Mutant-expressing 32D Cells after Exposure to Type I and Type II FLT3 Inhibitors
Published on: October 17, 2025
Identification of an orally available compound with potent and broad FLT3 inhibition activity
1Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
Abstract:
FLT3 internal tandem duplication (FLT3-ITD) is an activating mutation found in 20-30% of patients with acute myeloid leukemia (AML), which makes FLT3 an attractive target for the treatment of AML. Although FLT3-mutant patients respond to current FLT3 inhibitors, relapse usually happens because of the acquisition of resistant secondary mutations at the FLT3 catalytic domain, which is mainly on D835. In the search for compounds with broad FLT3 inhibition activities, we screened a kinase inhibitor library by using our unique FLT3 substrate and identified JAK3 inhibitor VI (designated JI6 hereafter) as a novel FLT3 inhibitor, which selectively targets FLT3 D835 mutants as well as FLT3-ITD. JI6 effectively inhibited FLT3-ITD-containing MV4-11 cells and HCD-57 cells transformed with FLT3-ITD and D835 mutants. Furthermore, administration of JI6 effectively targeted FLT3 signaling in vivo and suppressed the myeloproliferative phenotypes in FLT3-ITD knock-in mice, and significantly prolonged the survival of immunodeficient mice implanted with the transformed HCD-57 cells. Therefore, JI6 is a promising candidate for the development of next-generation anti-AML drugs.
Insights
A novel drug, JAK3 inhibitor VI (JI6), effectively targets FLT3 mutations common in acute myeloid leukemia (AML). JI6 shows promise as a next-generation therapy, overcoming resistance mechanisms in FLT3-mutant AML.
Area of Science:
- Oncology
- Molecular Biology
- Drug Discovery
Background:
- Activating FLT3 mutations, including internal tandem duplication (FLT3-ITD) and D835 mutations, are prevalent in acute myeloid leukemia (AML).
- Current FLT3 inhibitors are effective but often lead to relapse due to secondary resistance mutations.
- FLT3 remains an attractive therapeutic target for AML treatment.
Purpose of the Study:
- To identify novel compounds with broad FLT3 inhibition activity.
- To evaluate the efficacy of JAK3 inhibitor VI (JI6) against FLT3 mutations, including resistance-conferring secondary mutations.
- To assess the therapeutic potential of JI6 in preclinical AML models.
Main Methods:
- Screening of a kinase inhibitor library using a unique FLT3 substrate.
- In vitro assays using AML cell lines (MV4-11, HCD-57) harboring FLT3-ITD and D835 mutations.
- In vivo studies in FLT3-ITD knock-in mice and immunodeficient mice xenograft models.
Main Results:
- JAK3 inhibitor VI (JI6) was identified as a novel FLT3 inhibitor with selective activity against FLT3-ITD and FLT3 D835 mutants.
- JI6 demonstrated potent inhibition of FLT3-mutant cell lines in vitro.
- JI6 effectively suppressed FLT3 signaling, reduced myeloproliferative phenotypes in vivo, and prolonged survival in preclinical AML models.
Conclusions:
- JI6 exhibits broad FLT3 inhibition, targeting both common and resistance-associated mutations.
- JI6 demonstrates significant preclinical efficacy in vitro and in vivo.
- JI6 represents a promising candidate for the development of next-generation anti-AML therapeutics.
