Activating JAK-mutations confer resistance to FLT3 kinase inhibitors in FLT3-ITD positive AML in vitro and in vivo

Christoph Rummelt, Sivahari P. Gorantla, Manja Meggendorfer, Anne Charlet, Cornelia Endres, Konstanze Döhner, Florian H. Heidel, Thomas Fischer, Torsten Haferlach, Justus Duyster, Nikolas von Bubnoff*

*Corresponding author for this work

Abstract

An important limitation of FLT3 tyrosine kinase inhibitors (TKIs) in FLT3-ITD positive AML is the development of resistance. To better understand resistance to FLT3 inhibition, we examined FLT3-ITD positive cell lines which had acquired resistance to midostaurin or sorafenib. In 6 out of 23 TKI resistant cell lines we were able to detect a JAK1 V658F mutation, a mutation that led to reactivation of the CSF2RB–STAT5 pathway. Knockdown of JAK1, or treatment with a JAK inhibitor, resensitized cells to FLT3 inhibition. Out of 136 patients with FLT3-ITD mutated AML and exposed to FLT3 inhibitor, we found seven different JAK family mutations in six of the cases (4.4%), including five bona fide, activating mutations. Except for one patient, the JAK mutations occurred de novo (n = 4) or displayed increasing variant allele frequency after exposure to FLT3 TKI (n = 1). In vitro each of the five activating variants were found to induce resistance to FLT3-ITD inhibition, which was then overcome by dual FLT3/JAK inhibition. In conclusion, our data characterize a novel mechanism of resistance to FLT3-ITD inhibition and may offer a potential therapy, using dual JAK and FLT3 inhibition.

Original languageEnglish
JournalLeukemia
ISSN0887-6924
DOIs
Publication statusPublished - 2020

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